POWER DRIVER FOR STEPPER MOTORS
INTEGRATED CIRCUITS
TMC2226 Datasheet
Step/Dir Drivers for Two-Phase Bipolar Stepper Motors up to 2.8A peak – StealthChop™ for Quiet
Movement – UART Interface Option – Sensorless Stall Detection StallGuard4.
APPLICATIONS
Compatible Design Upgrade
3D Printers
Printers, POS
Office and home automation
Textile, Sewing Machines
CCTV, Security
ATM, Cash recycler
HVAC
Battery Operated Equipment
4
FEATURES
AND
BENEFITS
2-phase stepper motors up to 2.8A coil current (peak), 2A RMS
STEP/DIR Interface with 8, 16, 32 or 64 microstep pin setting
Smooth Running 256 microsteps by MicroPlyer™ interpolation
StealthChop2™ silent motor operation
SpreadCycle™ highly dynamic motor control chopper
StallGuard4™ load and stall detection for StealthChop
CoolStep™ current control for energy savings up to 75%
Low RDSon, Low Heat-Up LS 170mΩ & HS 170mΩ (typ. at 25°C)
Voltage Range 4.75… 29V DC
Low Power Standby to fit standby energy regulations
Internal Sense Resistor option (no sense resistors required)
Passive Braking, Freewheeling, and automatic power down
Single Wire UART & OTP for advanced configuration options
Integrated Pulse Generator for standalone motion
Full Protection & Diagnostics
Thermally optimized HTSSOP package for optical inspection
BLOCK DIAGRAM
TRINAMIC Motion Control GmbH & Co. KG
Hamburg, Germany
DESCRIPTION
The TMC2226 is an ultra-silent motor driver
IC for two phase stepper motors. TRINAMICs
sophisticated StealthChop2 chopper ensures
noiseless operation, maximum efficiency
and best motor torque. Its fast current
regulation and optional combination with
SpreadCycle allow highly dynamic motion
while adding. StallGuard for sensorless
homing. The integrated power MOSFETs
handle motor currents up to 2A RMS with
protection and diagnostic features for robust
and reliable operation. A simple to use UART
interface opens up tuning and control
options. Store application tuning to OTP
memory.
Industries’
most
advanced
STEP/DIR stepper motor driver family
upgrades designs to noiseless and most
precise operation for cost-effective and
highly competitive solutions.
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
2
APPLICATION EXAMPLES: SIMPLE SOLUTIONS – HIGHLY EFFECTIVE
The TMC22xx family scores with power density, integrated power MOSFETs, smooth and quiet operation,
and a congenial simplicity. The TMC2226 covers a wide spectrum of applications from battery systems
to embedded applications with up to 2A motor current per coil. TRINAMICs unique chopper modes
SpreadCycle and StealthChop2 optimize drive performance. StealthChop reduces motor noise to the
point of silence at low velocities. Standby current reduction keeps costs for power dissipation and
cooling down. Extensive support enables rapid design cycles and fast time-to-market with competitive
products.
STANDALONE REPLACEMENT
FOR
LEGACY STEPPER DRIVER
0A+
S/D
ERROR, INDEX
TMC22xx
S
0A-
N
0B+
0B-
UART
INTERFACE FOR
FULL DIAGNOSTICS
AND
CONTROL
0A+
S/D
High-Level
Interface
CPU
UART
TMC22xx
0A0B+
0B-
Sense Resistors may be omitted
S
N
In this example, configuration is hard
wired via pins. Software based motion
control generates STEP and DIR
(direction) signals, INDEX and ERROR
signals report back status information.
A CPU operates the driver via step and
direction signals. It accesses diagnostic
information
and
configures
the
TMC2226 via the UART interface. The CPU
manages motion control and the
TMC2226 drives the motor and smoothens and optimizes drive performance.
The TMC2226-EVAL is part of TRINAMICs
universal evaluation board system
which provides a convenient handling
of the hardware as well as a userfriendly software tool for evaluation.
The TMC2226 evaluation board system
consists of three parts: STARTRAMPE
(base board), ESELSBRÜCKE (connector
board with several test points and
stand-alone settings), and TMC2226EVAL.
ORDER CODES
Order code
TMC2226-SA
TMC2226-SA-T
TMC2226-EVAL
ESELSBRÜCKE
LANDUNGSBRÜCKE
www.trinamic.com
PN
00-0199
00-0199-T
40-0204
40-0098
40-0167
Description
StealthChop standalone driver; HTSSOP (RoHS compliant)
-T denotes tape on reel packing of devices
Evaluation board for TMC2226 stepper motor driver
Connector board fitting to Landungsbrücke
Baseboard for TMC2226-EVAL & further evaluation boards
Size [mm2]
9.7 x 6.4
85 x 55
61 x 38
85 x 55
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
3
Table of Contents
1
PRINCIPLES OF OPERATION ......................... 4
1.1
1.2
1.3
1.4
1.5
KEY CONCEPTS ................................................ 5
CONTROL INTERFACES ..................................... 6
MOVING AND CONTROLLING THE MOTOR ........ 6
STEALTHCHOP2 & SPREADCYCLE DRIVER ....... 6
STALLGUARD4 – MECHANICAL LOAD SENSING .
....................................................................... 7
1.6
COOLSTEP – LOAD ADAPTIVE CURRENT
CONTROL ...................................................................... 7
1.7
AUTOMATIC STANDSTILL POWER DOWN......... 7
1.8
INDEX OUTPUT ................................................ 8
1.9
PRECISE CLOCK GENERATOR AND CLK INPUT... 8
2
PIN ASSIGNMENTS ........................................... 9
2.1
2.2
3
SAMPLE CIRCUITS ..........................................11
3.1
3.2
3.3
3.4
3.5
3.6
3.7
4
10
INTERNAL SENSE RESISTORS ..................... 53
11
STALLGUARD4 LOAD MEASUREMENT ....... 55
11.1
11.2
11.3
11.4
11.5
12
COOLSTEP OPERATION ................................. 57
12.1
12.2
12.3
13
STALLGUARD4 VS. STALLGUARD2 ................ 55
TUNING STALLGUARD4................................. 56
STALLGUARD4 UPDATE RATE ....................... 56
DETECTING A MOTOR STALL ......................... 56
LIMITS OF STALLGUARD4 OPERATION .......... 56
USER BENEFITS............................................. 57
SETTING UP FOR COOLSTEP .......................... 57
TUNING COOLSTEP ....................................... 59
STEP/DIR INTERFACE .................................... 60
13.1 TIMING ......................................................... 60
13.2 CHANGING RESOLUTION ............................... 61
13.3 MICROPLYER STEP INTERPOLATOR AND STAND
STILL DETECTION ....................................................... 62
13.4 INDEX OUTPUT ............................................. 63
14
INTERNAL STEP PULSE GENERATOR ......... 64
15
DRIVER DIAGNOSTIC FLAGS ...................... 65
15.1
15.2
15.3
15.4
TEMPERATURE MEASUREMENT ....................... 65
SHORT PROTECTION ...................................... 65
OPEN LOAD DIAGNOSTICS ........................... 66
DIAGNOSTIC OUTPUT ................................... 66
16
QUICK CONFIGURATION GUIDE ................ 67
17
EXTERNAL RESET ............................................. 71
REGISTER MAP .................................................19
18
CLOCK OSCILLATOR AND INPUT ............... 71
19
ABSOLUTE MAXIMUM RATINGS ................. 72
20
ELECTRICAL CHARACTERISTICS ................. 72
GENERAL REGISTERS .....................................20
VELOCITY DEPENDENT CONTROL ...................25
STALLGUARD CONTROL .................................26
SEQUENCER REGISTERS .................................28
CHOPPER CONTROL REGISTERS .....................29
STEALTHCHOP™ ..............................................35
6.1
6.2
6.3
6.4
6.5
6.6
6.7
7
ANALOG CURRENT SCALING VREF ............... 51
DATAGRAM STRUCTURE .................................15
CRC CALCULATION .......................................17
UART SIGNALS ............................................17
ADDRESSING MULTIPLE SLAVES ....................18
5.1
5.2
5.3
5.4
5.5
6
STANDARD APPLICATION CIRCUIT ................11
INTERNAL RDSON SENSING..........................11
5V ONLY SUPPLY..........................................12
CONFIGURATION PINS ..................................13
HIGH MOTOR CURRENT .................................13
LOW POWER STANDBY .................................14
DRIVER PROTECTION AND EME CIRCUITRY ...14
UART SINGLE WIRE INTERFACE ................14
4.1
4.2
4.3
4.4
5
PACKAGE OUTLINE TMC2226 ........................ 9
SIGNAL DESCRIPTIONS TMC2226 .................. 9
9.1
AUTOMATIC TUNING .....................................35
STEALTHCHOP OPTIONS ................................37
STEALTHCHOP CURRENT REGULATOR.............37
VELOCITY BASED SCALING ............................39
COMBINE STEALTHCHOP AND SPREADCYCLE .41
FLAGS IN STEALTHCHOP ...............................42
FREEWHEELING AND PASSIVE BRAKING ........43
SPREADCYCLE CHOPPER ...............................45
7.1
SPREADCYCLE SETTINGS ...............................46
8
SELECTING SENSE RESISTORS ....................49
9
MOTOR CURRENT CONTROL ........................50
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20.1
20.2
20.3
21
LAYOUT CONSIDERATIONS ......................... 78
21.1
21.2
21.3
21.4
22
OPERATIONAL RANGE ................................... 72
DC AND TIMING CHARACTERISTICS .............. 73
THERMAL CHARACTERISTICS.......................... 77
EXPOSED DIE PAD ........................................ 78
WIRING GND .............................................. 78
SUPPLY FILTERING........................................ 78
LAYOUT EXAMPLE TMC2226 ........................ 79
PACKAGE MECHANICAL DATA .................... 80
22.1
22.2
DIMENSIONAL DRAWINGS HTSSOP28 ........ 80
PACKAGE CODES ........................................... 81
23
TABLE OF FIGURES ......................................... 82
24
REVISION HISTORY ....................................... 83
25
REFERENCES ...................................................... 83
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
1
4
Principles of Operation
The TMC22xx family of stepper drivers is intended as a drop-in upgrade for existing low-cost stepper
driver applications. Their silent drive technology StealthChop enables non-bugging motion control for
home and office applications. A highly efficient power stage enables high current from a tiny package.
The TMC2226 requires just a few control pins on its tiny package. It allows selection of the most
important setting: the desired microstep resolution. A choice of 8, 16, 32 or 64 microsteps, or from
fullstep up to 1/256 step adapts the driver to the capabilities of the motion controller.
STEP
DIR
5V Voltage
regulator
Step&Dir input
Analog Scaling
VREF
PDN/UART
Configuration
Interface
B. Dwersteg, ©
TRINAMIC 2016
UART interface
+ Register Block
DIAG
INDEX
opt. ext. clock
10-16MHz
CLK_IN
3.3V or 5V
I/O voltage
VCC_IO
VCP
OA2
BRA
stealthChop2
256 Microstep
Sequencer
Driver
Integrated
Rsense
S
N
stepper
motor
RSA
IREF
Connect directly
to GND plane
Use low inductivity SMD
type, e.g. 1206, 0.5W for
RSA and RSB
spreadCycle
Programmable
Diagnostic
Outputs
100µF
Low ESR type
Full Bridge A
OB1
coolStep
Full Bridge B
OB2
stallGuard4
Trimmed
CLK oscillator/
selector
BRB
RSB
Connect directly
to GND plane
opt. low power standby
opt. driver enable
GND
100n
ENN
Driver error
Index pulse
100n
OA1
STDBY
optional UART interface
MS2
SPREAD
100n
charge pump
IREF
Stand Still
Current
Reduction
Configuration
Memory (OTP)
microPlyer
MS1
+VM
VS
Step Pulse
Generator
Configuration
(GND or VCC_IO)
100n
16V
TMC2226
DIE PAD
Step and Direction
motion control
22n
50V
CPI
2.2µ
6.3V
5VOUT
Place near IC with
short path to die pad
CPO
VREF Analog current
scaling or leave
open
Even at low microstepping rate, the TMC2226 offers a number of unique enhancements over comparable
products: TRINAMICs sophisticated StealthChop2 chopper plus the microstep enhancement MicroPlyer
ensure noiseless operation, maximum efficiency and best motor torque. Its fast current regulation and
optional combination with SpreadCycle allow for highly dynamic motion. Protection and diagnostic
features support robust and reliable operation. A simple-to-use 8 bit UART interface opens up more
tuning and control options. Application specific tuning can be stored to on-chip OTP memory. Industries’
most advanced step & direction stepper motor driver family upgrades designs to noiseless and most
precise operation for cost-effective and highly competitive solutions.
Figure 1.1 TMC2226 basic application block diagram
THREE MODES OF OPERATION:
OPTION 1: Standalone STEP/DIR Driver (Legacy Mode)
A CPU (µC) generates step & direction signals synchronized to additional motors and other components
within the system. The TMC2226 operates the motor as commanded by the configuration pins and
STEP/DIR signals. Motor run-current either is fixed, or set by the CPU using the analog input VREF. The
pin PDN_UART selects automatic standstill current reduction. Feedback from the driver to the CPU is
granted by the INDEX and DIAG output signals. Enable or disable the motor using the ENN pin.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
5
OPTION 2: Standalone STEP/DIR Driver with OTP pre-configuration
Additional options enabled by pre-programming OTP memory (label UART & OTP):
+
+
+
UART
OTP
Tuning of the chopper to the application for application tailored performance
Cost reduction by switching the driver to internal sense resistor mode
Adapting the automatic power down level and timing for best application efficiency
0A+
S/D
High-Level
Interface
CPU
ERROR, INDEX
TMC22xx
0A-
S
N
0B+
TXD only or bit
bang UART
Other drivers
0B-
External preprogramming
Figure 1.2 Stand-alone driver with pre-configuration
To enable the additional options, either one-time program the driver’s OTP memory, or store
configuration in the CPU and transfer it to the on-chip registers following each power-up. Operation
uses the same signals as Option 1. Programming does not need to be done within the application - it
can be executed during testing of the PCB! Alternatively, use bit-banging by CPU firmware to configure
the driver. Multiple drivers can be programmed at the same time using a single TXD line.
OPTION 3: STEP/DIR Driver with Full Diagnostics and Control
Similar to Option 2, but pin PDN_UART is connected to the CPU UART interface.
UART
Additional options (label UART):
+
+
+
+
+
Detailed diagnostics and thermal management
Passive braking and freewheeling for flexible, lowest power stop modes
More options for microstep resolution setting (fullstep to 256 microstep)
Software controlled motor current setting and more chopper options
Use StallGuard for sensorless homing and CoolStep for adaptive motor current and cool motor
This mode allows replacing all control lines like ENN, DIAG, INDEX, MS1, MS2, and analog current setting
VREF by a single interface line. This way, only three signals are required for full control: STEP, DIR and
PDN_UART. Even motion without external STEP pulses is provided by an internal programmable step
pulse generator: Just set the desired motor velocity. However, no ramping is provided by the TMC2226.
1.1 Key Concepts
The TMC2226 implements advanced features which are exclusive to TRINAMIC products. These features
contribute toward greater precision, greater energy efficiency, higher reliability, smoother motion, and
cooler operation in many stepper motor applications.
StealthChop2™ No-noise, high-precision chopper algorithm for inaudible motion and inaudible
standstill of the motor. Allows faster motor acceleration and deceleration than
StealthChop™ and extends StealthChop to low stand still motor currents.
SpreadCycle™
High-precision cycle-by-cycle current control for highest dynamic movements.
MicroPlyer™
Microstep interpolator for obtaining full 256 microstep smoothness with lower
resolution step inputs starting from fullstep
StallGuard4™
Sensorless homing safes end switches and warns in case of motor overload
CoolStep™
Uses StallGuard measurement in order to adapt the motor current for best efficiency
and lowest heat-up of motor and driver
In addition to these performance enhancements, TRINAMIC motor drivers offer safeguards to detect and
protect against shorted outputs, output open-circuit, overtemperature, and undervoltage conditions for
enhancing safety and recovery from equipment malfunctions.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
6
1.2 Control Interfaces
The TMC2226 supports both, discrete control lines for basic mode selection and a UART based single
wire interface with CRC checking. The UART interface automatically becomes enabled when correct UART
data is sent. When using UART, the pin selection may be disabled by control bits.
1.2.1
UART Interface
UART
The single wire interface allows unidirectional operation (for parameter setting only), or bi-directional
operation for full control and diagnostics. It can be driven by any standard microcontroller UART or
even by bit banging in software. Baud rates from 9600 Baud to 500k Baud or even higher (when using
an external clock) may be used. No baud rate configuration is required, as the TMC2226 automatically
adapts to the masters’ baud rate. The frame format is identical to the intelligent TRINAMIC controller &
driver ICs TMC5130, TMC516x and TMC5072. A CRC checksum allows data transmission over longer
distance. For fixed initialization sequences, store the data including CRC into the µC, thus consuming
only a few 100 bytes of code for a full initialization. CRC may be ignored during read access, if not
desired. This makes CRC use an optional feature! The IC supports four address settings to access up to
four ICs on a single bus. Even more drivers can be programmed in parallel by tying together all interface
pins, in case no read access is required. An optional addressing can be provided by analog multiplexers,
like 74HC4066.
From a software point of view the TMC2226 is a peripheral with a number of control and status registers.
Most of them can either be written only or are read only. Some of the registers allow both, read and
write access. In case read-modify-write access is desired for a write only register, realize a shadow
register in master software.
1.3 Moving and Controlling the Motor
1.3.1
STEP/DIR Interface
The motor is controlled by a step and direction input. Active edges on the STEP input can be rising
edges or both rising and falling edges as controlled by a special mode bit (DEDGE). Using both edges
cuts the toggle rate of the STEP signal in half, which is useful for communication over slow interfaces
such as optically isolated interfaces. The state sampled from the DIR input upon an active STEP edge
determines whether to step forward or back. Each step can be a fullstep or a microstep, in which there
are 2, 4, 8, 16, 32, 64, 128, or 256 microsteps per fullstep. A step impulse with a low state on DIR
increases the microstep counter. With a high state, it decreases the counter by an amount controlled
by the microstep resolution. An internal table translates the counter value into the sine and cosine
values which control the motor current for microstepping.
1.3.2 Internal Step Pulse Generator
UART
Some applications do not require a precisely co-ordinate motion – the motor just is required to move
for a certain time and at a certain velocity. The TMC2226 comes with an internal pulse generator for
these applications: Just provide the velocity via UART interface to move the motor. The velocity sign
automatically controls the direction of the motion. However, the pulse generator does not integrate a
ramping function. Motion at higher velocities will require ramping up and ramping down the velocity
value via software.
STEP/DIR mode and internal pulse generator mode can be mixed in an application!
1.4 StealthChop2 & SpreadCycle Driver
StealthChop is a voltage-chopper based principle. It especially guarantees that the motor is absolutely
quiet in standstill and in slow motion, except for noise generated by ball bearings. Unlike other voltage
mode choppers, StealthChop2 does not require any configuration. It automatically learns the best
settings during the first motion after power up and further optimizes the settings in subsequent
motions. An initial homing sequence is sufficient for learning. Optionally, initial learning parameters
can be stored to OTP. StealthChop2 allows high motor dynamics, by reacting at once to a change of
motor velocity.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
7
For highest velocity applications, SpreadCycle is an option to StealthChop2. It can be enabled via input
pin or via UART and OTP. StealthChop2 and SpreadCycle may even be used in a combined configuration
for the best of both worlds: StealthChop2 for no-noise stand still, silent and smooth performance,
SpreadCycle at higher velocity for high dynamics and highest peak velocity at low vibration.
SpreadCycle is an advanced cycle-by-cycle chopper mode. It offers smooth operation and good
resonance dampening over a wide range of speed and load. The SpreadCycle chopper scheme
automatically integrates and tunes fast decay cycles to guarantee smooth zero crossing performance.
Benefits of using StealthChop2:
- Significantly improved microstepping with low cost motors
- Motor runs smooth and quiet
- Absolutely no standby noise
- Reduced mechanical resonance yields improved torque
1.5 StallGuard4 – Mechanical Load Sensing
StallGuard4 provides an accurate measurement of the load on the motor. It can be used for stall
detection as well as other uses at loads below those which stall the motor, such as CoolStep loadadaptive current reduction. This gives more information on the drive allowing functions like sensorless
homing and diagnostics of the drive mechanics.
1.6 CoolStep – Load Adaptive Current Control
coolStep drives the motor at the optimum current. It uses the stallGuard4 load measurement information
to adjust the motor current to the minimum amount required in the actual load situation. This saves
energy and keeps the components cool.
Benefits are:
- Energy efficiency
- Motor generates less heat
- Less or no cooling
- Use of smaller motor
- Less motor noise
power consumption decreased up to 75%
improved mechanical precision
improved reliability
less torque reserve required → cheaper motor does the job
Due to less energy exciting motor resonances
Figure 1.3 shows the efficiency gain of a 42mm stepper motor when using coolStep compared to
standard operation with 50% of torque reserve. coolStep is enabled above 60RPM in the example.
0,9
Efficiency with coolStep
0,8
Efficiency with 50% torque reserve
0,7
0,6
0,5
Efficiency
0,4
0,3
0,2
0,1
0
0
50
100
150
200
250
300
350
Velocity [RPM]
Figure 1.3 Energy efficiency with coolStep (example)
1.7 Automatic Standstill Power Down
An automatic current reduction drastically reduces application power dissipation and cooling
requirements. Per default, the stand still current reduction is enabled by pulling PDN_UART input to
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
8
GND. It reduces standstill power dissipation to less than 33% by going to slightly more than half of the
run current.
Modify stand still current, delay time and decay via UART, or pre-programmed via internal OTP. Automatic
freewheeling and passive motor braking are provided as an option for stand still. Passive braking
reduces motor standstill power consumption to zero, while still providing effective dampening and
braking!
STEP
CURRENT
IRUN
IHOLD
RMS motor current trace with pin PDN=0
TPOWERDOWN IHOLDDELAY
power down power down
ramp time
delay time
t
Figure 1.4 Automatic Motor Current Power Down
1.8 Index Output
The index output gives one pulse per electrical rotation, i.e. one pulse per each four fullsteps. It shows
the internal sequencer microstep 0 position (MSTEP near 0). This is the power on position. In
combination with a mechanical home switch, a more precise homing is enabled.
1.9 Precise clock generator and CLK input
The TMC2226 provides a factory trimmed internal clock generator for precise chopper frequency and
performance. However, an optional external clock input is available for cases, where quartz precision is
desired, or where a lower or higher frequency is required. For safety, the clock input features timeout
detection, and switches back to internal clock upon fail of the external source.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
2
9
Pin Assignments
The TMC2226 comes in a thermally optimized HTSSOP-package.
22
19
10
11
18
9
20
8
© B. Dwersteg,
TRINAMIC
12
14
15
13
16
Pad=GND
17
7
TMC2226
HTSSOP28
21
6
23
5
24
4
25
3
26
2
27
1
OB1
BRB
VS
OB2
ENN
GND
CPO
CPI
VCP
SPREAD
5VOUT
MS1_AD0
MS2_AD1
28
2.1 Package Outline TMC2226
OA1
BRA
VS
OA2
STDBY
DIR
GND
VREF
STEP
VCC_IO
PDN_UART
CLK
INDEX
DIAG
Figure 2.1 TMC2226 Pinning Top View – type: HTSSOP 28, 9.7x6.4mm² over pins, 0.65mm pitch
2.2 Signal Descriptions TMC2226
Pin
OB1
Number
1
BRB
2
VS
3, 26
OB2
4
ENN
5
GND
CPO
CPI
VCP
6, 22
7
8
9
SPREAD
10
5VOUT
11
MS1_AD0
12
DI (pd)
MS2_AD1
14
DI (pd)
DIAG
15
DO
INDEX
16
DO
CLK
17
DI
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Type
DI
DI (pd)
Function
Motor coil B output 1
Sense resistor connection for coil B. Place sense resistor to GND
near pin. Tie to GND when using internal sense resistor.
Motor supply voltage. Provide filtering capacity near pin with
shortest possible loop to GND pad.
Motor coil B output 2
Enable not input. The power stage becomes switched off (all motor
outputs floating) when this pin becomes driven to a high level.
GND. Connect to GND plane near pin.
Charge pump capacitor output.
Charge pump capacitor input. Tie to CPO using 22nF 50V capacitor.
Charge pump voltage. Tie to VS using 100nF capacitor.
Chopper mode selection: Low=StealthChop, High=SpreadCycle
(may be left unconnected)
Output of internal 5V regulator. Attach 2.2µF to 4.7µF ceramic
capacitor to GND near to pin for best performance. Provide the
shortest possible loop to the GND pad.
Microstep resolution configuration (internal pull-down resistors)
MS2, MS1: 00: 1/8, 01: 1/32, 10: 1/64 11: 1/16
For UART based configuration selection of UART Address 0…3
Diagnostic and StallGuard output. Hi level upon stall detection or
driver error. Reset error condition by ENN=high.
Configurable index output. Provides index pulse.
CLK input. Tie to GND using short wire for internal clock or supply
external clock.
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
Pin
Number
Type
PDN_UART
18
DIO
VCC_IO
STEP
19
20
DI
VREF
21
AI
DIR
23
DI (pd)
STDBY
24
DI (pd)
OA2
25
BRA
27
OA1
-
28
13
Exposed
die pad
-
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unused
10
Function
Power down not control input (low = automatic standstill current
reduction).
Optional UART Input/Output. Power down function can be disabled
in UART mode.
3.3V to 5V IO supply voltage for all digital pins.
STEP input
Analog reference voltage for current scaling or reference current for
use of internal sense resistors (optional mode)
DIR input (internal pull-down resistor)
STANDBY input. Pull up to disable driver internal supply regulator.
This will bring the driver into a low power dissipation state.
100kOhm pulldown. (may be left unconnected)
Hint: Also shut down VREF voltage and ENN to 0V during standby.
Motor coil A output 2
Sense resistor connection for coil A. Place sense resistor to GND
near pin. Tie to GND when using internal sense resistor.
Motor coil A output 1
May be connected to GND for better PCB routing
Connect the exposed die pad to a GND plane. Provide as many as
possible vias for heat transfer to GND plane. Serves as GND pin for
power drivers and analogue circuitry.
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
3
11
Sample Circuits
The sample circuits show the connection of external components in different operation and supply
modes. The connection of the bus interface and further digital signals is left out for clarity.
STEP
DIR
5V Voltage
regulator
Step&Dir input
Analog Scaling
PDN/UART
Configuration
Memory (OTP)
B. Dwersteg, ©
TRINAMIC 2016
DIAG
INDEX
opt. ext. clock
10-16MHz
CLK_IN
3.3V or 5V
I/O voltage
VCC_IO
CPI
VCP
OA2
BRA
Driver
Integrated
Rsense
S
N
stepper
motor
RSA
IREF
Connect directly
to GND plane
Use low inductivity SMD
type, e.g. 1206, 0.5W for
RSA and RSB
spreadCycle
Programmable
Diagnostic
Outputs
100µF
Low ESR type
Full Bridge A
OB1
coolStep
Full Bridge B
OB2
stallGuard4
Trimmed
CLK oscillator/
selector
BRB
RSB
Connect directly
to GND plane
opt. low power standby
opt. driver enable
GND
ENN
100n
STDBY
Index pulse
256 Microstep
Sequencer
100n
OA1
stealthChop2
Configuration
Interface
UART interface
+ Register Block
Driver error
100n
charge pump
IREF
Stand Still
Current
Reduction
microPlyer
optional UART interface
MS2
SPREAD
+VM
VS
VREF
Configuration
(GND or VCC_IO)
100n
16V
TMC2226
Step Pulse
Generator
MS1
22n
50V
DIE PAD
Step and Direction
motion control
CPO
2.2µ
6.3V
5VOUT
Place near IC with
short path to die pad
VREF Analog current
scaling or leave
open
3.1 Standard Application Circuit
Figure 3.1 Standard application circuit
The standard application circuit uses a minimum set of additional components. Two sense resistors set
the motor coil current. See chapter 8 to choose the right sense resistors. Use low ESR capacitors for
filtering the power supply. The capacitors need to cope with the current ripple cause by chopper
operation. A minimum capacity of 100µF near the driver is recommended for best performance. Current
ripple in the supply capacitors also depends on the power supply internal resistance and cable length.
VCC_IO can be supplied from 5VOUT, or from an external source, e.g. a 3.3V regulator.
Basic layout hints
Place sense resistors and all filter capacitors as close as possible to the related IC pins. Use a solid
common GND for all GND connections, also for sense resistor GND. Connect 5VOUT filtering capacitor
directly to 5VOUT and the die pad. See layout hints for more details. Low ESR electrolytic capacitors are
recommended for VS filtering.
3.2 Internal RDSon Sensing
For cost critical or space limited applications, sense resistors can be omitted. For internal current sensing,
a reference current set by a tiny external resistor programs the output current. For calculation of the
reference resistor, refer chapter 9.1.
Attention
Be sure to switch the IC to RDSon mode, before enabling drivers: Set otp_internalRsense = 1.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
12
STEP
Step and Direction
motion control
DIR
Configuration
Interface
PDN/UART
B. Dwersteg, ©
TRINAMIC 2016
UART interface
+ Register Block
DIAG
INDEX
opt. ext. clock
10-16MHz
CLK_IN
3.3V or 5V
I/O voltage
VCC_IO
100µF
IREF
Low ESR type
OA1
Full Bridge A
256 Microstep
Sequencer
OA2
BRA
Integrated
Rsense
Driver
S
N
stepper
motor
Connect directly
to GND plane
IREF
Attention:
Start with ENN=high!
Set GCONF.1 or OTP0.6
prior to enabling the driver!
spreadCycle
Programmable
Diagnostic
Outputs
100n
charge pump
stealthChop2
microPlyer
MS2
100n
Analog Scaling
Stand Still
Current
Reduction
Configuration
Memory (OTP)
SPREAD
Driver error
CPO
VREF
5V Voltage
regulator
Step&Dir input
MS1
Index pulse
+VM
VS
VREF
OB1
coolStep
Full Bridge B
OB2
stallGuard4
Trimmed
CLK oscillator/
selector
BRB
Connect directly
to GND plane
opt. low power standby
opt. driver enable
GND
ENN
DIE PAD
100n
STDBY
optional UART interface
100n
16V
TMC2226
Step Pulse
Generator
Configuration
(GND/open or VCC_IO)
22n
50V
VCP
RREF
5VOUT
2.2µ
6.3V
CPI
Place near IC with
short path to die pad
Figure 3.2 Application circuit using RDSon based sensing
STEP
DIR
5V Voltage
regulator
Step&Dir input
Configuration
Interface
PDN/UART
B. Dwersteg, ©
TRINAMIC 2016
UART interface
+ Register Block
INDEX
opt. ext. clock
10-16MHz
CLK_IN
3.3V or 5V
I/O voltage
VCC_IO
VCP
IREF
256 Microstep
Sequencer
100µF
Low ESR type
Full Bridge A
OA2
BRA
Driver
Integrated
Rsense
S
N
stepper
motor
RSA
IREF
Connect directly
to GND plane
Use low inductivity SMD
type, e.g. 1206, 0.5W for
RSA and RSB
spreadCycle
Programmable
Diagnostic
Outputs
100n
OA1
OB1
coolStep
Full Bridge B
OB2
stallGuard4
Trimmed
CLK oscillator/
selector
BRB
RSB
Connect directly
to GND plane
opt. low power standby
opt. driver enable
GND
ENN
100n
STDBY
Driver error
100n
charge pump
stealthChop2
microPlyer
MS2
SPREAD
Index pulse
CPO
Analog Scaling
Stand Still
Current
Reduction
Configuration
Memory (OTP)
MS1
DIAG
4.7-5.4V
VS
VREF
optional UART interface
100n
16V
TMC2226
Step Pulse
Generator
Configuration
(GND/open or VCC_IO)
22n
50V
DIE PAD
Step and Direction
motion control
10R
Optional – bridges the internal 5V
reference – leave away if standby is
desired
VREF
10µ
6.3V
5VOUT
Place near IC with
short path to die pad
CPI
3.3 5V Only Supply
Figure 3.3 5V only operation
While the standard application circuit is limited to roughly 5.2 V lower supply voltage, a 5 V only
application lets the IC run from a 5 V +/-5% supply. In this application, linear regulator drop must be
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
13
minimized. Therefore, the internal 5V regulator is filtered with a higher capacitance. An optional resistor
bridges the internal 5V regulator by connecting 5VOUT to the external power supply. This RC filter keeps
chopper ripple away from 5VOUT. With this resistor, the external supply is the reference for the absolute
motor current and must not exceed 5.5V. Standby function will not work in this application, because
the 5V regulator is bridged.
3.4 Configuration Pins
The TMC2226 provides four configuration pins. These pins allow quick configuration for standalone
operation. Several additional options can be set by OTP programming. In UART mode, the configuration
pins can be disabled in order to set a different configuration via registers.
PDN_UART: CONFIGURATION OF STANDSTILL POWER DOWN
PDN_UART
GND
VCC_IO
UART interface
Current Setting
Enable automatic power down in standstill periods
Disable
When using the UART interface, the configuration pin should be disabled via
GCONF.pdn_disable = 1. Program IHOLD as desired for standstill periods.
MS1/MS2: CONFIGURATION OF MICROSTEP RESOLUTION FOR STEP INPUT
MS2
GND
GND
VCC_IO
VCC_IO
MS1
GND
VCC_IO
GND
VCC_IO
Microstep Setting
8 microsteps
32 microsteps (different to TMC2208!)
64 microsteps (different to TMC2208!)
16 microsteps
SPREAD: SELECTION OF CHOPPER MODE
SPREAD
GND or
Pin open / not
available
VCC_IO
Chopper Setting
StealthChop is selected. Automatic switching to SpreadCycle in dependence of the
step frequency can be programmed via OTP.
SpreadCycle operation.
3.5 High Motor Current
When operating at a high motor current, the driver power dissipation due to MOSFET switch onresistance significantly heats up the driver. This power dissipation will significantly heat up the PCB
cooling infrastructure, if operated at an increased duty cycle. This in turn leads to a further increase of
driver temperature. An increase of temperature by about 100°C increases MOSFET resistance by roughly
50%. This is a typical behavior of MOSFET switches. Therefore, under high duty cycle, high load
conditions, thermal characteristics have to be carefully taken into account, especially when increased
environment temperatures are to be supported. Refer the thermal characteristics and the layout hints
for more information. As a thumb rule, thermal properties of the PCB design become critical for the
HTSSOP package at or above 1.6A RMS motor current for increased periods of time. Keep in mind that
resistive power dissipation rises with the square of the motor current. On the other hand, this means
that a small reduction of motor current significantly saves heat dissipation and energy.
Pay special attention to good thermal properties of your PCB layout, when going for 1.4A RMS current
or more.
An effect which might be perceived at medium motor velocities and motor sine wave peak currents
above roughly 2A peak is a slight sine distortion of the current wave when using SpreadCycle. It results
from an increasing negative impact of parasitic internal diode conduction, which in turn negatively
influences the duration of the fast decay cycle of the SpreadCycle chopper. This is, because the current
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
14
measurement does not see the full coil current during this phase of the sine wave, because an increasing
part of the current flows directly from the power MOSFETs’ drain to GND and does not flow through
the sense resistor. This effect with most motors does not negatively influence the smoothness of
operation, as it does not impact the critical current zero transition. The effect does not occur with
StealthChop.
3.6 Low Power Standby
Battery powered applications, and mains powered applications conforming to standby energy saving
rules, often require a standby operation, where the power-supply remains on, but current draw goes
down to a low value. The TMC2226 supports standby operation of roughly 2mW (at 12V supply), or
TPWMTHRS
- CoolStep is enabled, if configured (only with StealthChop)
- Stall output signal on pin DIAG is enabled
SGTHRS
Detection threshold for stall. The StallGuard value SG_RESULT
becomes compared to the double of this threshold.
A stall is signaled with
SG_RESULT ≤ SGTHRS*2
StallGuard result. SG_RESULT becomes updated with each
fullstep, independent of TCOOLTHRS and SGTHRS. A higher value
signals a lower motor load and more torque headroom.
Intended for StealthChop mode, only. Bits 9 and 0 will always
show 0. Scaling to 10 bit is for compatibility to StallGuard2.
CoolStep configuration
See separate table!
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
5.3.1
27
COOLCONF – Smart Energy Control CoolStep
0X42: COOLCONF – SMART ENERGY CONTROL COOLSTEP AND STALLGUARD
Bit
…
15
Name
Function
Comment
seimin
minimum current for
smart current control
14
13
sedn1
sedn0
current down step
speed
12
11
10
9
8
7
6
5
4
3
2
1
0
semax3
semax2
semax1
semax0
seup1
seup0
semin3
semin2
semin1
semin0
reserved
StallGuard hysteresis
value for smart current
control
0: 1/2 of current setting (IRUN)
Attention: use with IRUN≥10
1: 1/4 of current setting (IRUN)
Attention: use with IRUN≥20
%00: For each 32 StallGuard4 values decrease by one
%01: For each 8 StallGuard4 values decrease by one
%10: For each 2 StallGuard4 values decrease by one
%11: For each StallGuard4 value decrease by one
set to 0
If the StallGuard4 result is equal to or above
(SEMIN+SEMAX+1)*32, the motor current becomes
decreased to save energy.
%0000 … %1111: 0 … 15
set to 0
Current increment steps per measured StallGuard value
%00 … %11: 1, 2, 4, 8
set to 0
If the StallGuard4 result falls below SEMIN*32, the motor
current becomes increased to reduce motor load angle.
%0000: smart current control CoolStep off
%0001 … %1111: 1 … 15
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reserved
current up step width
reserved
minimum StallGuard
value for smart current
control and
smart current enable
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
28
5.4 Sequencer Registers
The sequencer registers have a pure informative character and are read-only. They help for special cases
like storing the last motor position before power off in battery powered applications.
MICROSTEPPING CONTROL REGISTER SET (0X60…0X6B)
R/W
Addr
n
Register
R
0x6A
10
MSCNT
R
0x6B
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9
+
9
MSCURACT
Description / bit names
Microstep counter. Indicates actual position in
the microstep table for CUR_A. CUR_B uses an
offset of 256 into the table. Reading out
MSCNT allows determination of the motor
position within the electrical wave.
bit 8… 0:
CUR_A (signed):
Actual microstep current for motor
phase A as read from the internal
sine wave table (not scaled by
current setting)
bit 24… 16: CUR_B (signed):
Actual microstep current for motor
phase B as read from the internal
sine wave table (not scaled by
current setting)
Range [Unit]
0…1023
+/-0...255
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
29
5.5 Chopper Control Registers
DRIVER REGISTER SET (0X6C…0X7F)
R/W
Addr
n
Register
RW
0x6C
32
CHOPCONF
R
0x6F
32
DRV_
STATUS
RW
0x70
22
PWMCONF
R
R
0x71
0x72
9+8
8+8
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PWM_SCALE
PWM_AUTO
Description / bit names
Chopper and driver configuration
See separate table!
Driver status flags and current level read back
See separate table!
StealthChop PWM chopper configuration
See separate table!
Results of StealthChop amplitude regulator.
These values can be used to monitor
automatic PWM amplitude scaling (255=max.
voltage).
bit 7… 0
PWM_SCALE_SUM:
Actual PWM duty cycle. This
value is used for scaling the
values CUR_A and CUR_B read
from the sine wave table.
bit 24… 16 PWM_SCALE_AUTO:
9 Bit signed offset added to the
calculated PWM duty cycle. This is
the result of the automatic
amplitude regulation based on
current measurement.
These automatically generated values can be
read out in order to determine a default /
power up setting for PWM_GRAD and
PWM_OFS.
bit 7… 0
PWM_OFS_AUTO:
Automatically determined offset
value
bit 23… 16 PWM_GRAD_AUTO:
Automatically
determined
gradient value
Range [Unit]
Reset default=
0x10000053
Reset default=
0xC10D0024
0…255
signed
-255…+255
0…255
0…255
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
5.5.1
30
CHOPCONF – Chopper Configuration
0X6C: CHOPCONF – CHOPPER CONFIGURATION
Bit
31
Name
diss2vs
30
diss2g
29
dedge
28
intpol
interpolation to 256
microsteps
27
26
25
24
mres3
mres2
mres1
mres0
MRES
micro step resolution
23
22
21
20
19
18
17
-
reserved
vsense
16
15
tbl1
tbl0
sense resistor voltage
based current scaling
TBL
blank time select
14
13
12
11
10
9
8
7
-
reserved
hend3
hend2
hend1
hend0
HEND
hysteresis low value
OFFSET
sine wave offset
6
5
4
hstrt2
hstrt1
hstrt0
HSTRT
hysteresis start value
added to HEND
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Function
Low side short
protection disable
short to GND
protection disable
enable double edge
step pulses
Comment
0: Short protection low side is on
1: Short protection low side is disabled
0: Short to GND protection is on
1: Short to GND protection is disabled
1: Enable step impulse at each step edge to reduce step
frequency requirement. This mode is not compatible
with the step filtering function (multistep_filt)
1: The actual microstep resolution (MRES) becomes
extrapolated to 256 microsteps for smoothest motor
operation.
(Default: 1)
%0000:
Native 256 microstep setting.
%0001 … %1000:
128, 64, 32, 16, 8, 4, 2, FULLSTEP
Reduced microstep resolution.
The resolution gives the number of microstep entries per
sine quarter wave.
When choosing a lower microstep resolution, the driver
automatically uses microstep positions which result in a
symmetrical wave.
Number of microsteps per step pulse = 2^MRES
(Selection by pins unless disabled by GCONF.
mstep_reg_select)
set to 0
0: Low sensitivity, high sense resistor voltage
1: High sensitivity, low sense resistor voltage
%00 … %11:
Set comparator blank time to 16, 24, 32 or 40 clocks
Hint: %00 or %01 is recommended for most applications
(Default: OTP)
set to 0
%0000 … %1111:
Hysteresis is -3, -2, -1, 0, 1, …, 12
(1/512 of this setting adds to current setting)
This is the hysteresis value which becomes used for the
hysteresis chopper.
(Default: OTP, resp. 5 in StealthChop mode)
%000 … %111:
Add 1, 2, …, 8 to hysteresis low value HEND
(1/512 of this setting adds to current setting)
Attention: Effective HEND+HSTRT ≤ 16.
Hint: Hysteresis decrement is done each 16 clocks
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
31
0X6C: CHOPCONF – CHOPPER CONFIGURATION
Bit
Name
Function
Comment
(Default: OTP, resp. 0 in StealthChop mode)
3
2
1
0
toff3
toff2
toff1
toff0
TOFF off time
and driver enable
Off time setting controls duration of slow decay phase
NCLK= 24 + 32*TOFF
%0000: Driver disable, all bridges off
%0001: 1 – use only with TBL ≥ 2
%0010 … %1111: 2 … 15
(Default: OTP, resp. 3 in StealthChop mode)
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
5.5.2
32
PWMCONF – Voltage PWM Mode StealthChop
0X70: PWMCONF – VOLTAGE MODE PWM STEALTHCHOP
Bit
31
30
29
28
Name
PWM_LIM
Function
PWM automatic scale
amplitude limit when
switching on
27
26
25
24
PWM_REG
Regulation loop
gradient
23
22
21
20
freewheel1
freewheel0
reserved
reserved
Allows different
standstill modes
19
pwm_
autograd
PWM automatic
gradient adaptation
18
pwm_
autoscale
PWM automatic
amplitude scaling
17
pwm_freq1
www.trinamic.com
Comment
Limit for PWM_SCALE_AUTO when switching back from
SpreadCycle to StealthChop. This value defines the upper
limit for bits 7 to 4 of the automatic current control when
switching back. It can be set to reduce the current jerk
during mode change back to StealthChop.
It does not limit PWM_GRAD or PWM_GRAD_AUTO offset.
(Default = 12)
User defined maximum PWM amplitude change per half
wave when using pwm_autoscale=1. (1…15):
1: 0.5 increments (slowest regulation)
2: 1 increment (default with OTP2.1=1)
3: 1.5 increments
4: 2 increments
…
8: 4 increments (default with OTP2.1=0)
...
15: 7.5 increments (fastest regulation)
set to 0
set to 0
Stand still option when motor current setting is zero
(I_HOLD=0).
%00: Normal operation
%01: Freewheeling
%10: Coil shorted using LS drivers
%11: Coil shorted using HS drivers
0
Fixed value for PWM_GRAD
(PWM_GRAD_AUTO = PWM_GRAD)
1
Automatic tuning (only with pwm_autoscale=1)
PWM_GRAD_AUTO is initialized with PWM_GRAD and
becomes optimized automatically during motion.
Preconditions
1. PWM_OFS_AUTO has been automatically
initialized. This requires standstill at IRUN for
>130ms in order to a) detect standstill b) wait >
128 chopper cycles at IRUN and c) regulate
PWM_OFS_AUTO so that
-1 < PWM_SCALE_AUTO < 1
2. Motor running and 1.5 * PWM_OFS_AUTO <
PWM_SCALE_SUM < 4* PWM_OFS_AUTO and
PWM_SCALE_SUM < 255.
Time required for tuning PWM_GRAD_AUTO
About 8 fullsteps per change of +/-1.
0
User defined feed forward PWM amplitude. The
current settings IRUN and IHOLD have no influence!
The resulting PWM amplitude (limited to 0…255) is:
PWM_OFS * ((CS_ACTUAL+1) / 32)
+ PWM_GRAD * 256 / TSTEP
1
Enable automatic current control (Reset default)
%00: fPWM=2/1024 fCLK
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
33
0X70: PWMCONF – VOLTAGE MODE PWM STEALTHCHOP
Bit
16
Name
pwm_freq0
Function
PWM frequency
selection
15
14
13
12
11
10
9
8
PWM_
GRAD
User defined amplitude
gradient
7
6
5
4
3
2
1
0
PWM_
OFS
User defined amplitude
(offset)
Comment
%01: fPWM=2/683 fCLK
%10: fPWM=2/512 fCLK
%11: fPWM=2/410 fCLK
Velocity dependent gradient for PWM amplitude:
PWM_GRAD * 256 / TSTEP
This value is added to PWM_AMPL to compensate for the
velocity-dependent motor back-EMF.
With automatic scaling (pwm_autoscale=1) the value is
used for first initialization, only. Set PWM_GRAD to the
application specific value (it can be read out from
PWM_GRAD_AUTO) to speed up the automatic tuning
process. An approximate value can be stored to OTP by
programming OTP_PWM_GRAD.
User defined PWM amplitude offset (0-255) related to full
motor current (CS_ACTUAL=31) in stand still.
(Reset default=36)
When using automatic scaling (pwm_autoscale=1) the
value is used for initialization, only. The autoscale
function starts with PWM_SCALE_AUTO=PWM_OFS and
finds the required offset to yield the target current
automatically.
PWM_OFS = 0 will disable scaling down motor current
below a motor specific lower measurement threshold.
This setting should only be used under certain conditions,
i.e. when the power supply voltage can vary up and down
by a factor of two or more. It prevents the motor going
out of regulation, but it also prevents power down below
the regulation limit.
PWM_OFS > 0 allows automatic scaling to low PWM duty
cycles even below the lower regulation threshold. This
allows low (standstill) current settings based on the
actual (hold) current scale (register IHOLD_IRUN).
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
5.5.3
34
DRV_STATUS – Driver Status Flags
0X6F: DRV_STATUS – DRIVER STATUS FLAGS AND CURRENT LEVEL READ BACK
Bit
31
Name
stst
Function
standstill indicator
30
stealth
StealthChop indicator
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
-
reserved
Comment
This flag indicates motor stand still in each operation
mode. This occurs 2^20 clocks after the last step pulse.
1: Driver operates in StealthChop mode
0: Driver operates in SpreadCycle mode
Ignore these bits.
-
reserved
Ignore these bits.
CS_
ACTUAL
actual motor current /
smart energy current
Actual current control scaling, for monitoring the
function of the automatic current scaling.
-
reserved
Ignore these bits.
t157
t150
t143
t120
olb
6
ola
5
s2vsb
4
s2vsa
3
s2gb
2
s2ga
1
ot
157°C comparator
150°C comparator
143°C comparator
120°C comparator
open load indicator
phase B
open load indicator
phase A
low side short
indicator phase B
low side short
indicator phase A
short to ground
indicator phase B
short to ground
indicator phase A
overtemperature flag
0
otpw
1: Temperature threshold is exceeded
1: Temperature threshold is exceeded
1: Temperature threshold is exceeded
1: Temperature threshold is exceeded
1: Open load detected on phase A or B.
Hint: This is just an informative flag. The driver takes no
action upon it. False detection may occur in fast motion
and standstill. Check during slow motion, only.
1: Short on low-side MOSFET detected on phase A or B.
The driver becomes disabled. The flags stay active, until
the driver is disabled by software (TOFF=0) or by the ENN
input. Flags are separate for both chopper modes.
1: Short to GND detected on phase A or B. The driver
becomes disabled. The flags stay active, until the driver is
disabled by software (TOFF=0) or by the ENN input. Flags
are separate for both chopper modes.
1: The selected overtemperature limit has been reached.
Drivers become disabled until otpw is also cleared due to
cooling down of the IC.
The overtemperature flag is common for both bridges.
1: The selected overtemperature pre-warning threshold is
exceeded.
The overtemperature pre-warning flag is common for
both bridges.
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overtemperature prewarning flag
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
6
35
StealthChop™
StealthChop is an extremely quiet mode of operation for stepper motors. It is based on a
voltage mode PWM. In case of standstill and at low velocities, the motor is absolutely
noiseless. Thus, StealthChop operated stepper motor applications are very suitable for
indoor or home use. The motor operates absolutely free of vibration at low velocities. With
StealthChop, the motor current is applied by driving a certain effective voltage into the
coil, using a voltage mode PWM. With the enhanced StealthChop2, the driver automatically adapts to
the application for best performance. No more configurations are required. Optional configuration allows
for tuning the setting in special cases, or for storing initial values for the automatic adaptation algorithm.
For high velocity consider SpreadCycle in combination with StealthChop.
Figure 6.1 Motor coil sine wave current with StealthChop (measured with current probe)
6.1 Automatic Tuning
StealthChop2 integrates an automatic tuning procedure (AT), which adapts the most important operating
parameters to the motor automatically. This way, StealthChop2 allows high motor dynamics and
supports powering down the motor to very low currents. Just two steps have to be respected by the
motion controller for best results: Start with the motor in standstill, but powered with nominal run
current (AT#1). Move the motor at a medium velocity, e.g. as part of a homing procedure (AT#2). Figure
6.2 shows the tuning procedure.
Border conditions in for AT#1 and AT#2 are shown in the following table:
AUTOMATIC TUNING TIMING AND BORDER CONDITIONS
Step
AT#1
Parameter
PWM_
OFS_AUTO
AT#2
PWM_
GRAD_AUTO
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Conditions
- Motor in standstill and actual current scale (CS) is
identical to run current (IRUN).
- If standstill reduction is enabled (pin PDN_UART=0),
an initial step pulse switches the drive back to run
current.
- Pins VS and VREF at operating level.
- Motor must move at a velocity, where a significant
amount of back EMF is generated and where the full
run current can be reached. Conditions:
- 1.5 * PWM_OFS_AUTO
<
PWM_SCALE_SUM
<
4 * PWM_OFS_AUTO
- PWM_SCALE_SUM < 255.
Hint: A typical range is 60-300 RPM. Determine best
conditions with the evaluation board and monitor
PWM_SCALE_AUTO going down to zero during tuning.
Duration
≤ 2^20+2*2^18 tCLK,
≤ 130ms
(with internal clock)
8 fullsteps are required for
a change of +/-1.
For a typical motor with
PWM_GRAD_AUTO
optimum at 64 or less, up
to 400 fullsteps are
required when starting
from OTP default 14.
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
36
Power Up
PWM_GRAD_AUTO becomes
initialized by OTP
Driver Enabled?
N
Y
Stand still
N
Y
N
AT#1
Driver Enabled?
Standstill reduction enabled?
Y
Issue (at least) a single step
pulse and stop again, to
power motor to run current
stealthChop2 regulates to nominal
current and stores result to
PWM_OFS_AUTO
(Requires stand still for >130ms)
PWM_
GRAD_AUTO stored
in OTP?
Y
N
AT#2
Homing
Move the motor, e.g. for homing.
Include a constant, medium velocity
ramp segment.
stealthChop2 regulates to nominal
current and optimizes PWM_GRAD_AUTO
(requires 8 fullsteps per change of 1,
typically a few 100 fullsteps in sum)
Ready
stealthChop2 settings are optimized!
Option with UART
Store PWM_GRAD_AUTO or
write to OTP for faster
tuning procedure
stealthChop2 keeps tuning during
subsequent motion and stand still periods
adapting to motor heating, supply
variations, etc.
Figure 6.2 StealthChop2 automatic tuning procedure
Attention
Modifying VREF or the supply voltage VS invalidates the result of the automatic tuning process. Motor
current regulation cannot compensate significant changes until next AT#1 phase. Automatic tuning
adapts to changed conditions whenever AT#1 and AT#2 conditions are fulfilled in the later operation.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
37
6.2 StealthChop Options
UART
In order to match the motor current to a certain level, the effective PWM voltage becomes scaled
depending on the actual motor velocity. Several additional factors influence the required voltage level
to drive the motor at the target current: The motor resistance, its back EMF (i.e. directly proportional to
its velocity) as well as the actual level of the supply voltage. Two modes of PWM regulation are provided:
The automatic tuning mode (AT) using current feedback (pwm_autoscale = 1, pwm_autograd = 1) and a
feed forward velocity-controlled mode (pwm_autoscale = 0). The feed forward velocity-controlled mode
will not react to a change of the supply voltage or to events like a motor stall, but it provides very
stable amplitude. It does not use nor require any means of current measurement. This is perfect when
motor type and supply voltage are well known. Therefore, we recommend the automatic mode, unless
current regulation is not satisfying in the given operating conditions.
It is recommended to operate in automatic tuning mode.
Non-automatic mode (pwm_autoscale=0) should be considered only with well-known motor and
operating conditions. In this case, programming via the UART interface is required. The operating
parameters PWM_GRAD and PWM_OFS can be determined in automatic tuning mode initially.
Hint: In non-automatic mode the power supply current directly reflects mechanical load on the motor.
The StealthChop PWM frequency can be chosen in four steps in order to adapt the frequency divider to
the frequency of the clock source. A setting in the range of 20-50kHz is good for most applications. It
balances low current ripple and good higher velocity performance vs. dynamic power dissipation.
CHOICE OF PWM FREQUENCY FOR STEALTHCHOP
Clock frequency
fCLK
PWM_FREQ=%00
fPWM=2/1024 fCLK
18MHz
16MHz
12MHz (internal)
10MHz
8MHz
35.2kHz
31.3kHz
23.4kHz
19.5kHz
15.6kHz
PWM_FREQ=%01
fPWM=2/683 fCLK
(default)
52.7kHz
46.9kHz
35.1kHz
29.3kHz
23.4kHz
PWM_FREQ=%10
fPWM=2/512 fCLK
(OTP option)
70.3kHz
62.5kHz
46.9kHz
39.1kHz
31.2kHz
PWM_FREQ=%11
fPWM=2/410 fCLK
87.8kHz
78.0kHz
58.5kHz
48.8kHz
39.0kHz
Table 6.1 Choice of PWM frequency – green / light green: recommended
6.3 StealthChop Current Regulator
In StealthChop voltage PWM mode, the autoscaling function (pwm_autoscale = 1, pwm_autograd = 1)
regulates the motor current to the desired current setting. Automatic scaling is used as part of the
automatic tuning process (AT), and for subsequent tracking of changes within the motor parameters.
The driver measures the motor current during the chopper on time and uses a proportional regulator
to regulate PWM_SCALE_AUTO in order match the motor current to the target current. PWM_REG is the
proportionality coefficient for this regulator. Basically, the proportionality coefficient should be as small
as possible in order to get a stable and soft regulation behavior, but it must be large enough to allow
the driver to quickly react to changes caused by variation of the motor target current (e.g. change of
VREF). During initial tuning step AT#2, PWM_REG also compensates for the change of motor velocity.
Therefore, a high acceleration during AT#2 will require a higher setting of PWM_REG. With careful
selection of homing velocity and acceleration, a minimum setting of the regulation gradient often is
sufficient (PWM_REG=1). PWM_REG setting should be optimized for the fastest required acceleration and
deceleration ramp (compare Figure 6.3 and Figure 6.4). The quality of the setting PWM_REG in phase
AT#2 and the finished automatic tuning procedure (or non-automatic settings for PWM_OFS and
PWM_GRAD) can be examined when monitoring motor current during an acceleration phase Figure 6.5.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
38
Figure 6.3 Scope shot: good setting for PWM_REG
Figure 6.4 Scope shot: too small setting for PWM_REG during AT#2
Motor Current
PWM scale
Motor Velocity
PWM reaches max. amplitude
RMS current constant
(IRUN)
PW
M_
Nominal Current
(sine wave RMS)
Stand still
PWM scale
PWM_OFS_(AUTO) ok
ok
O)
UT
(_A
AD
GR
M_
PW
GR
(P
AD
W
M_
(_A
RE
UT
G
O)
du
ok
rin
g
AT
#2
ok
)
255
Current may drop due
to high velocity
IHOLD
PWM_OFS_(AUTO) ok
0
0
Figure 6.5 Successfully determined PWM_GRAD(_AUTO) and PWM_OFS(_AUTO)
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Time
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
39
Quick Start
For a quick start, see the Quick Configuration Guide in chapter 16.
6.3.1
Lower Current Limit
The StealthChop current regulator imposes a lower limit for motor current regulation. As the coil current
can be measured in the shunt resistor during chopper on phase only, a minimum chopper duty cycle
allowing coil current regulation is given by the blank time as set by TBL and by the chopper frequency
setting. Therefore, the motor specific minimum coil current in StealthChop autoscaling mode rises with
the supply voltage and with the chopper frequency. A lower blanking time allows a lower current limit.
It is important for the correct determination of PWM_OFS_AUTO, that in AT#1 the run current set by the
sense resistor, VREF and IRUN is well within the regulation range. Lower currents (e.g. for standstill
power down) are automatically realized based on PWM_OFS_AUTO and PWM_GRAD_AUTO respectively
based on PWM_OFS and PWM_GRAD with non-automatic current scaling. The freewheeling option allows
going to zero motor current.
Lower motor coil current limit for StealthChop2 automatic tuning:
𝐼𝐿𝑜𝑤𝑒𝑟 𝐿𝑖𝑚𝑖𝑡 = 𝑡𝐵𝐿𝐴𝑁𝐾 ∗ 𝑓𝑃𝑊𝑀 ∗
𝑉𝑀
𝑅𝐶𝑂𝐼𝐿
With VM the motor supply voltage and RCOIL the motor coil resistance.
ILower Limit can be treated as a thumb value for the minimum nominal IRUN motor current setting.
EXAMPLE:
A motor has a coil resistance of 5Ω, the supply voltage is 24V. With TBL=%01 and PWM_FREQ=%00, tBLANK
is 24 clock cycles, fPWM is 2/(1024 clock cycles):
𝐼𝐿𝑜𝑤𝑒𝑟 𝐿𝑖𝑚𝑖𝑡 = 24 𝑡𝐶𝐿𝐾 ∗
2
24𝑉
24 24𝑉
∗
=
∗
= 225𝑚𝐴
1024 𝑡𝐶𝐿𝐾 5Ω
512 5Ω
This means, the motor target current for automatic tuning must be 225mA or more, taking into account
all relevant settings. This lower current limit also applies for modification of the motor current via the
analog input VREF.
Attention
For automatic tuning, a lower coil current limit applies. The motor current in automatic tuning phase
AT#1 must exceed this lower limit. ILOWER LIMIT can be calculated or measured using a current probe.
Setting the motor run-current or hold-current below the lower current limit during operation by
modifying IRUN and IHOLD is possible after successful automatic tuning.
With StealthChop, ensure that IRUN is in the range 8 to 31. Set vsense to yield lower current setting!
The lower current limit also limits the capability of the driver to respond to changes of VREF.
6.4 Velocity Based Scaling
UART
Velocity based scaling scales the StealthChop amplitude based on the time between each two steps,
i.e. based on TSTEP, measured in clock cycles. This concept basically does not require a current
measurement, because no regulation loop is necessary. A pure velocity-based scaling is available via
UART programming, only, when setting pwm_autoscale = 0. The basic idea is to have a linear
approximation of the voltage required to drive the target current into the motor. The stepper motor has
a certain coil resistance and thus needs a certain voltage amplitude to yield a target current based on
the basic formula I=U/R. With R being the coil resistance, U the supply voltage scaled by the PWM value,
the current I results. The initial value for PWM_AMPL can be calculated:
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
𝑃𝑊𝑀_𝐴𝑀𝑃𝐿 =
40
374 ∗ 𝑅𝐶𝑂𝐼𝐿 ∗ 𝐼𝐶𝑂𝐼𝐿
𝑉𝑀
With VM the motor supply voltage and ICOIL the target RMS current
The effective PWM voltage UPWM (1/SQRT(2) x peak value) results considering the 8 bit resolution and 248
sine wave peak for the actual PWM amplitude shown as PWM_SCALE:
𝑈𝑃𝑊𝑀 = 𝑉𝑀 ∗
𝑃𝑊𝑀_𝑆𝐶𝐴𝐿𝐸 248 1
𝑃𝑊𝑀_𝑆𝐶𝐴𝐿𝐸
∗
∗
= 𝑉𝑀 ∗
256
256 √2
374
With rising motor velocity, the motor generates an increasing back EMF voltage. The back EMF voltage
is proportional to the motor velocity. It reduces the PWM voltage effective at the coil resistance and
thus current decreases. The TMC2226 provides a second velocity dependent factor (PWM_GRAD) to
compensate for this. The overall effective PWM amplitude (PWM_SCALE_SUM) in this mode automatically
is calculated in dependence of the microstep frequency as:
𝑓𝑆𝑇𝐸𝑃
𝑓𝐶𝐿𝐾
With fSTEP being the microstep frequency for 256 microstep resolution equivalent
and fCLK the clock frequency supplied to the driver or the actual internal frequency
𝑃𝑊𝑀_𝑆𝐶𝐴𝐿𝐸_𝑆𝑈𝑀 = 𝑃𝑊𝑀_𝑂𝐹𝑆 + 𝑃𝑊𝑀_𝐺𝑅𝐴𝐷 ∗ 256 ∗
As a first approximation, the back EMF subtracts from the supply voltage and thus the effective current
amplitude decreases. This way, a first approximation for PWM_GRAD setting can be calculated:
𝑃𝑊𝑀_𝐺𝑅𝐴𝐷 = 𝐶𝐵𝐸𝑀𝐹 [
𝑉
𝑓𝐶𝐿𝐾 ∗ 1.46
] ∗ 2𝜋 ∗
𝑟𝑎𝑑
𝑉𝑀 ∗ 𝑀𝑆𝑃𝑅
𝑠
CBEMF is the back EMF constant of the motor in Volts per radian/second.
MSPR is the number of microsteps per rotation, e.g. 51200 = 256µsteps multiplied by 200 fullsteps for a
1.8° motor.
Motor current
PWM scaling
(PWM_SCALE_SUM)
255
PWM reaches
max. amplitude
Constant motor
RMS current
Nominal current
(e.g. sine wave RMS)
AD
GR
_
M
PW
Cur
r
(de ent dr
p en
ops
mo
d
tor s on
loa
d)
PWM_OFS
0
0
VPWMMAX
Figure 6.6 Velocity based PWM scaling (pwm_autoscale=0)
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Velocity
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
41
Hint
The values for PWM_OFS and PWM_GRAD can easily be optimized by tracing the motor current with a
current probe on the oscilloscope. Alternatively, automatic tuning determines these values and they can
be read out from PWM_OFS_AUTO and PWM_GRAD_AUTO.
UNDERSTANDING THE BACK EMF CONSTANT OF A MOTOR
The back EMF constant is the voltage a motor generates when turned with a certain velocity. Often
motor datasheets do not specify this value, as it can be deducted from motor torque and coil current
rating. Within SI units, the back EMF constant CBEMF has the same numeric value as the torque constant.
For example, a motor with a torque constant of 1 Nm/A would have a CBEMF of 1V/rad/s. Turning such a
motor with 1 rps (1 rps = 1 revolution per second = 6.28 rad/s) generates a back EMF voltage of 6.28V.
Thus, the back EMF constant can be calculated as:
𝐶𝐵𝐸𝑀𝐹 [
𝑉
𝐻𝑜𝑙𝑑𝑖𝑛𝑔𝑇𝑜𝑟𝑞𝑢𝑒[𝑁𝑚]
]=
𝑟𝑎𝑑/𝑠
2 ∗ 𝐼𝐶𝑂𝐼𝐿𝑁𝑂𝑀 [𝐴]
ICOILNOM is the motor’s rated phase current for the specified holding torque
HoldingTorque is the motor specific holding torque, i.e. the torque reached at ICOILNOM on both coils. The
torque unit is [Nm] where 1Nm = 100Ncm = 1000mNm.
The BEMF voltage is valid as RMS voltage per coil, thus the nominal current has a factor of 2 in this
formula.
6.5 Combine StealthChop and SpreadCycle
UART
OTP
For applications requiring high velocity motion, SpreadCycle may bring more stable operation in the
upper velocity range. To combine no-noise operation with highest dynamic performance, the TMC2226
allows combining StealthChop and SpreadCycle based on a velocity threshold (Figure 6.7). A velocity
threshold (TPWMTHRS) can be preprogrammed to OTP to support this mode even in standalone
operation. With this, StealthChop is only active at low velocities.
Chopper mode
stealthChop
spreadCycle
option
option
motor going to standby
motor in standby
motor stand still
Running low speed
Running high speed
Running low speed
TSTEP < TPWMTHRS*16/16
TSTEP > TPWMTHRS
motor in standby
v
0
t
RMS current
TRINAMIC, B. Dwersteg, 14.3.14
Figure 6.7 TPWMTHRS for optional switching to SpreadCycle
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dI * IHOLDDELAY
VACTUAL
~1/TSTEP
TPOWERDOWN
current
I_RUN
I_HOLD
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
42
As a first step, both chopper principles should be parameterized and optimized individually (SpreadCycle
settings may be programmed to OTP memory). In a next step, a transfer velocity has to be fixed. For
example, StealthChop operation is used for precise low speed positioning, while SpreadCycle shall be
used for highly dynamic motion. TPWMTHRS determines the transition velocity. Read out TSTEP when
moving at the desired velocity and program the resulting value to TPWMTHRS. Use a low transfer
velocity to avoid a jerk at the switching point.
A jerk occurs when switching at higher velocities, because the back-EMF of the motor (which rises with
the velocity) causes a phase shift of up to 90° between motor voltage and motor current. So when
switching at higher velocities between voltage PWM and current PWM mode, this jerk will occur with
increased intensity. A high jerk may even produce a temporary overcurrent condition (depending on the
motor coil resistance). At low velocities (e.g. 1 to a few 10 RPM), it can be completely neglected for
most motors. Therefore, consider the switching jerk when choosing TPWMTHRS. Set TPWMTHRS zero if
you want to work with StealthChop only.
When enabling the StealthChop mode the first time using automatic current regulation, the motor must
be at stand still in order to allow a proper current regulation. When the drive switches to StealthChop
at a higher velocity, StealthChop logic stores the last current regulation setting until the motor returns
to a lower velocity again. This way, the regulation has a known starting point when returning to a
lower velocity, where StealthChop becomes re-enabled. Therefore, neither the velocity threshold nor the
supply voltage must be considerably changed during the phase while the chopper is switched to a
different mode, because otherwise the motor might lose steps or the instantaneous current might be
too high or too low.
A motor stall or a sudden change in the motor velocity may lead to the driver detecting a short circuit
or to a state of automatic current regulation, from which it cannot recover. Clear the error flags and
restart the motor from zero velocity to recover from this situation.
Hint
Start the motor from standstill when switching on StealthChop the first time and keep it stopped for
at least 128 chopper periods to allow StealthChop to do initial standstill current control.
6.6 Flags in StealthChop
UART
As StealthChop uses voltage mode driving, status flags based on current measurement respond slower,
respectively the driver reacts delayed to sudden changes of back EMF, like on a motor stall.
Attention
A motor stall, or abrupt stop of the motion during operation in StealthChop can trigger an overcurrent
condition. Depending on the previous motor velocity, and on the coil resistance of the motor, it
significantly increases motor current for a time of several 10ms. With low velocities, where the back
EMF is just a fraction of the supply voltage, there is no danger of triggering the short detection. When
homing using StallGuard4 to stop the motor upon stall, this is basically avoided.
6.6.1
Open Load Flags
In StealthChop mode, status information is different from the cycle-by-cycle regulated SpreadCycle mode.
OLA and OLB show if the current regulation sees that the nominal current can be reached on both coils.
-
A flickering OLA or OLB can result from asymmetries in the sense resistors or in the motor coils.
An interrupted motor coil leads to a continuously active open load flag for the coil.
One or both flags are active, if the current regulation did not succeed in scaling up to the full
target current within the last few fullsteps (because no motor is attached or a high velocity
exceeds the PWM limit).
If desired, do an on-demand open load test using the SpreadCycle chopper, as it delivers the safest
result. With StealthChop, PWM_SCALE_SUM can be checked to detect the correct coil resistance.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
6.6.2
43
PWM_SCALE_SUM Informs about the Motor State
Information about the motor state is available with automatic scaling by reading out PWM_SCALE_SUM.
As this parameter reflects the actual voltage required to drive the target current into the motor, it
depends on several factors: motor load, coil resistance, supply voltage, and current setting. Therefore,
an evaluation of the PWM_SCALE_SUM value allows checking the motor operation point. When reaching
the limit (255), the current regulator cannot sustain the full motor current, e.g. due to a drop in supply
volage.
6.7 Freewheeling and Passive Braking
UART
StealthChop provides different options for motor standstill. These options can be enabled by setting
the standstill current IHOLD to zero and choosing the desired option using the FREEWHEEL setting. The
desired option becomes enabled after a time period specified by TPOWERDOWN and IHOLD_DELAY.
Current regulation becomes frozen once the motor target current is at zero current in order to ensure
a quick startup. With the freewheeling options, both freewheeling and passive braking can be realized.
Passive braking is an effective eddy current motor braking, which consumes a minimum of energy,
because no active current is driven into the coils. However, passive braking will allow slow turning of
the motor when a continuous torque is applied.
Hint
Operate the motor within your application when exploring StealthChop. Motor performance often is
better with a mechanical load, because it prevents the motor from stalling due mechanical oscillations
which can occur without load.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
44
PARAMETERS RELATED TO STEALTHCHOP
Parameter
en_spread_
cycle
TPWMTHRS
PWM_LIM
pwm_
autoscale
pwm_
autograd
Description
General disable for use of StealthChop (register
GCONF). The input SPREAD is XORed to this flag.
Specifies the upper velocity for operation in
StealthChop. Entry the TSTEP reading (time between
two microsteps) when operating at the desired
threshold velocity.
Limiting value for limiting the current jerk when
switching from SpreadCycle to StealthChop. Reduce
the value to yield a lower current jerk.
Enable automatic current scaling using current
measurement or use forward controlled velocity
based mode.
Enable automatic tuning of PWM_GRAD_AUTO
Setting
1
0
0…
1048575
Comment
Do not use StealthChop
StealthChop enabled
StealthChop is disabled if
TSTEP falls TPWMTHRS
0 … 15
Upper four bits of 8 bit
amplitude limit
(Default=12)
Forward controlled mode
Automatic scaling with
current regulator
disable, use PWM_GRAD
from register instead
enable
fPWM=2/1024 fCLK
fPWM=2/683 fCLK
fPWM=2/512 fCLK
fPWM=2/410 fCLK
Results in 0.5 to 7.5 steps
for PWM_SCALE_AUTO
regulator per fullstep
PWM_OFS=0 disables
linear current scaling
based on current setting
Reset value can be preprogrammed by OTP
0
1
0
1
0
1
2
3
PWM_REG
User defined PWM amplitude (gradient) for velocity 1 … 15
based scaling or regulation loop gradient when
pwm_autoscale=1.
PWM_OFS
User defined PWM amplitude (offset) for velocity 0 … 255
based scaling and initialization value for automatic
tuning of PWM_OFFS_AUTO.
PWM_GRAD User defined PWM amplitude (gradient) for velocity 0 … 255
based scaling and initialization value for automatic
tuning of PWM_GRAD_AUTO.
FREEWHEEL Stand still option when motor current setting is 0
zero (I_HOLD=0). Only available with StealthChop 1
enabled. The freewheeling option makes the motor 2
easy movable, while both coil short options realize 3
a passive brake.
PWM_SCALE Read back of the actual StealthChop voltage PWM -255 …
_AUTO
scaling correction as determined by the current 255
regulator. Should regulate to a value close to 0
during tuning procedure.
PWM_GRAD Allow monitoring of the automatic tuning and 0 … 255
_AUTO
determination of initial values for PWM_OFS and
PWM_OFS
PWM_GRAD.
_AUTO
TOFF
General enable for the motor driver, the actual 0
value does not influence StealthChop
1 … 15
TBL
Comparator blank time. This time needs to safely 0
cover the switching event and the duration of the 1
ringing on the sense resistor. Choose a setting of 1 2
or 2 for typical applications. For higher capacitive 3
loads, 3 may be required. Lower settings allow
StealthChop to regulate down to lower coil current
values.
PWM_FREQ
PWM frequency selection. Use the lowest setting
giving good results. The frequency measured at
each of the chopper outputs is half of the effective
chopper frequency fPWM.
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Normal operation
Freewheeling
Coil short via LS drivers
Coil short cia HS drivers
(read only) Scaling value
becomes frozen when
operating in SpreadCycle
(read only)
Driver off
Driver enabled
16 tCLK
24 tCLK
32 tCLK
40 tCLK
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
7
45
SpreadCycle Chopper
While StealthChop is a voltage mode PWM controlled chopper, SpreadCycle is a cycle-by-cycle current
control. Therefore, it can react extremely fast to changes in motor velocity or motor load. SpreadCycle
will give better performance in medium to high velocity range for motors and applications which tend
to resonance. The currents through both motor coils are controlled using choppers. The choppers work
independently of each other. In Figure 7.1 the different chopper phases are shown.
+VM
+VM
+VM
ICOIL
ICOIL
ICOIL
RSENSE
On Phase:
current flows in
direction of target
current
RSENSE
Fast Decay Phase:
current flows in
opposite direction
of target current
RSENSE
Slow Decay Phase:
current re-circulation
Figure 7.1 Chopper phases
Although the current could be regulated using only on phases and fast decay phases, insertion of the
slow decay phase is important to reduce electrical losses and current ripple in the motor. The duration
of the slow decay phase is specified in a control parameter and sets an upper limit on the chopper
frequency. The current comparator can measure coil current during phases when the current flows
through the sense resistor, but not during the slow decay phase, so the slow decay phase is terminated
by a timer. The on phase is terminated by the comparator when the current through the coil reaches
the target current. The fast decay phase may be terminated by either the comparator or another timer.
When the coil current is switched, spikes at the sense resistors occur due to charging and discharging
parasitic capacitances. During this time, typically one or two microseconds, the current cannot be
measured. Blanking is the time when the input to the comparator is masked to block these spikes.
The SpreadCycle chopper mode cycles through four phases: on, slow decay, fast decay, and a second
slow decay.
The chopper frequency is an important parameter for a chopped motor driver. A too low frequency
might generate audible noise. A higher frequency reduces current ripple in the motor, but with a too
high frequency magnetic losses may rise. Also power dissipation in the driver rises with increasing
frequency due to the increased influence of switching slopes causing dynamic dissipation. Therefore, a
compromise needs to be found. Most motors are optimally working in a frequency range of 16 kHz to
30 kHz. The chopper frequency is influenced by a number of parameter settings as well as by the motor
inductivity and supply voltage.
Hint
A chopper frequency in the range of 16 kHz to 30 kHz gives a good result for most motors when using
SpreadCycle. A higher frequency leads to increased switching losses.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
7.1 SpreadCycle Settings
46
UART
OTP
The SpreadCycle (patented) chopper algorithm is a precise and simple to use chopper mode which
automatically determines the optimum length for the fast-decay phase. The SpreadCycle will provide
superior microstepping quality even with default settings. Several parameters are available to optimize
the chopper to the application.
Each chopper cycle is comprised of an on phase, a slow decay phase, a fast decay phase and a second
slow decay phase (see Figure 7.3). The two slow decay phases and the two blank times per chopper
cycle put an upper limit to the chopper frequency. The slow decay phases typically make up for about
30%-70% of the chopper cycle in standstill and are important for low motor and driver power dissipation.
Calculation of a starting value for the slow decay time TOFF:
EXAMPLE:
Target Chopper frequency: 25kHz.
Assumption: Two slow decay cycles make up for 50% of overall chopper cycle time
𝑡𝑂𝐹𝐹 =
For the TOFF setting this means:
1
50 1
∗
∗ = 10µ𝑠
25𝑘𝐻𝑧 100 2
𝑇𝑂𝐹𝐹 = (𝑡𝑂𝐹𝐹 ∗ 𝑓𝐶𝐿𝐾 − 24)/32
With 12 MHz clock this gives a setting of TOFF=3.0, i.e. 3.
With 16 MHz clock this gives a setting of TOFF=4.25, i.e. 4 or 5.
The hysteresis start setting forces the driver to introduce a minimum amount of current ripple into the
motor coils. The current ripple must be higher than the current ripple which is caused by resistive losses
in the motor in order to give best microstepping results. This will allow the chopper to precisely regulate
the current both for rising and for falling target current. The time required to introduce the current
ripple into the motor coil also reduces the chopper frequency. Therefore, a higher hysteresis setting will
lead to a lower chopper frequency. The motor inductance limits the ability of the chopper to follow a
changing motor current. Further the duration of the on phase and the fast decay must be longer than
the blanking time, because the current comparator is disabled during blanking.
It is easiest to find the best setting by starting from a low hysteresis setting (e.g. HSTRT=0, HEND=0)
and increasing HSTRT, until the motor runs smoothly at low velocity settings. This can best be checked
when measuring the motor current either with a current probe or by probing the sense resistor voltages
(see Figure 7.2). Checking the sine wave shape near zero transition will show a small ledge between
both half waves in case the hysteresis setting is too small. At medium velocities (i.e. 100 to 400 fullsteps
per second), a too low hysteresis setting will lead to increased humming and vibration of the motor.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
47
Figure 7.2 No ledges in current wave with sufficient hysteresis (magenta: current A, yellow & blue:
sense resistor voltages A and B)
A too high hysteresis setting will lead to reduced chopper frequency and increased chopper noise but
will not yield any benefit for the wave shape.
Quick Start
For a quick start, see the Quick Configuration Guide in chapter 16.
For detail procedure see Application Note AN001 - Parameterization of SpreadCycle
As experiments show, the setting is quite independent of the motor, because higher current motors
typically also have a lower coil resistance. Therefore, choosing a low to medium default value for the
hysteresis (for example, effective hysteresis = 4) normally fits most applications. The setting can be
optimized by experimenting with the motor: A too low setting will result in reduced microstep accuracy,
while a too high setting will lead to more chopper noise and motor power dissipation. When measuring
the sense resistor voltage in motor standstill at a medium coil current with an oscilloscope, a too low
setting shows a fast decay phase not longer than the blanking time. When the fast decay time becomes
slightly longer than the blanking time, the setting is optimum. You can reduce the off-time setting, if
this is hard to reach.
The hysteresis principle could in some cases lead to the chopper frequency becoming too low, e.g.
when the coil resistance is high when compared to the supply voltage. This is avoided by splitting the
hysteresis setting into a start setting (HSTRT+HEND) and an end setting (HEND). An automatic hysteresis
decrementer (HDEC) interpolates between both settings, by decrementing the hysteresis value stepwise
each 16 system clocks. At the beginning of each chopper cycle, the hysteresis begins with a value which
is the sum of the start and the end values (HSTRT+HEND), and decrements during the cycle, until either
the chopper cycle ends or the hysteresis end value (HEND) is reached. This way, the chopper frequency
is stabilized at high amplitudes and low supply voltage situations, if the frequency gets too low. This
avoids the frequency reaching the audible range.
Hint
Highest motor velocities sometimes benefit from setting TOFF to 1 or 2 and a short TBL of 1 or 0.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
I
target current + hysteresis start
48
HDEC
target current + hysteresis end
target current
target current - hysteresis end
target current - hysteresis start
on
sd
fd
sd
t
Figure 7.3 SpreadCycle chopper scheme showing coil current during a chopper cycle
These parameters control SpreadCycle mode:
Parameter
TOFF
TBL
HSTRT
HEND
Description
Sets the slow decay time (off time). This setting also
limits the maximum chopper frequency.
For operation with StealthChop, this parameter is not
used, but it is required to enable the motor. In case
of operation with StealthChop only, any setting is OK.
Setting this parameter to zero completely disables all
driver transistors and the motor can free-wheel.
Comparator blank time. This time needs to safely
cover the switching event and the duration of the
ringing on the sense resistor. For most applications,
a setting of 1 or 2 is good. For highly capacitive
loads, a setting of 2 or 3 will be required.
Setting
0
1…15
Comment
chopper off
off time setting
NCLK= 24 + 32*TOFF
(1 will work with minimum
blank time of 24 clocks)
0
16 tCLK
1
24 tCLK
2
32 tCLK
3
40 tCLK
Hysteresis start setting. This value is an offset from 0…7
the hysteresis end value HEND.
HSTRT=1…8
Hysteresis end setting. Sets the hysteresis end value 0…2
after a number of decrements. The sum HSTRT+HEND 3
must be ≤16. At a current setting of max. 30 (amplitude
4…15
reduced to 240), the sum is not limited.
-3…-1: negative HEND
This value adds to HEND.
0: zero HEND
1…12: positive HEND
Even at HSTRT=0 and HEND=0, the TMC2226 sets a minimum hysteresis via analog circuitry.
EXAMPLE:
A hysteresis of 4 has been chosen. You might decide to not use hysteresis decrement. In this case set:
HEND=6
HSTRT=0
(sets an effective end value of 6-3=3)
(sets minimum hysteresis, i.e. 1: 3+1=4)
In order to take advantage of the variable hysteresis, we can set most of the value to the HSTRT, i.e. 4,
and the remaining 1 to hysteresis end. The resulting configuration register values are as follows:
HEND=0
HSTRT=6
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(sets an effective end value of -3)
(sets an effective start value of hysteresis end +7: 7-3=4)
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
8
49
Selecting Sense Resistors
Set the desired maximum motor current by selecting an appropriate value for the sense resistor. The
following table shows the RMS current values which can be reached using standard resistors and motor
types fitting without additional motor current scaling.
CHOICE OF RSENSE AND RESULTING MAX. MOTOR CURRENT
RSENSE [Ω]
1.00
0.82
0.75
0.68
0.50
470m
390m
330m
270m
220m
180m
150m
120m
100m
75m
*) Value
RMS current [A]
Fitting motor type
VREF=2.5V (or open),
(examples)
IRUN=31,
vsense=0 (standard)
0.23
0.27
0.30
300mA motor
0.33
400mA motor
0.44
0.47
500mA motor
0.56
600mA motor
0.66
700mA motor
0.79
800mA motor
0.96
1A motor
1.15
1.2A motor
1.35
1.5A motor
1.64
1.7A motor
1.92
2A motor
2.4*)
exceeds upper current rating, scaling down required, e.g. by reduced VREF.
Sense resistors should be carefully selected. The full motor current flows through the sense resistors.
Due to chopper operation the sense resistors see pulsed current from the MOSFET bridges. Therefore, a
low-inductance type such as film or composition resistors is required to prevent voltage spikes causing
ringing on the sense voltage inputs leading to unstable measurement results. Also, a low-inductance,
low-resistance PCB layout is essential. Any common GND path for the two sense resistors must be
avoided, because this would lead to coupling between the two current sense signals. A massive ground
plane is best. Please also refer to layout considerations in chapter 21.
The sense resistor needs to be able to conduct the peak motor coil current in motor standstill conditions,
unless standby power is reduced. Under normal conditions, the sense resistor conducts less than the
coil RMS current, because no current flows through the sense resistor during the slow decay phases. A
0.5W type is sufficient for most applications up to 1.2A RMS current.
Attention
Be sure to use a symmetrical sense resistor layout and short and straight sense resistor traces of
identical length. Well matching sense resistors ensure best performance.
A compact layout with massive ground plane is best to avoid parasitic resistance effects.
Check the resulting motor current in a practical application and with the desired motor.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
9
50
Motor Current Control
The basic motor current is set by the resistance of the sense resistors. Several possibilities allow scaling
down motor current, e.g. to adapt for different motors, or to reduce motor current in standstill or low
load situations.
METHODS FOR SCALING MOTOR CURRENT
Method
Pin VREF
voltage
(chapter 9.1)
Parameters
VREF input scales
IRUN and IHOLD.
Can be disabled by
GCONF.i_scale_analog
Range
2.5V: 100% …
0.5V: 20%
>2.5V or open: 100%
20kHz
0-2.4V for
current scaling
22k
1µ
R1+R2»10K
Analog Scaling
Fixed resistor divider to set current scale
(use external reference for enhanced precision)
Analog Scaling
Precision current scaler
Figure 9.1 Scaling the motor current using the analog input
www.trinamic.com
VREF
BC847
VREF
100k
VREF
Optional
digital
control
Analog Scaling
Simple PWM based current scaler
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
53
10 Internal Sense Resistors
UART
OTP
The TMC2226 provides the option to eliminate external sense resistors. In this mode the external sense
resistors become omitted (shorted) and the internal on-resistance of the power MOSFETs is used for
current measurement (see chapter 3.2). As MOSFETs are both, temperature dependent and subject to
production stray, a tiny external resistor connected from +5VOUT to VREF provides a precise absolute
current reference. This resistor converts the 5V voltage into a reference current. Be sure to directly attach
BRA and BRB pins to GND in this mode near the IC package. The mode is enabled by setting
internal_Rsense in GCONF (OTP option).
COMPARING INTERNAL SENSE RESISTORS VS. SENSE RESISTORS
Item
Ease of use
Cost
Current precision
Current Range
Recommended
Recommended
chopper
Internal Sense Resistors
Need to set OTP parameter
before motor enable
(+) Save cost for sense resistors
Slightly reduced
200mA RMS to 1.4A RMS
External Sense Resistors
(+) Default
StealthChop or SpreadCycle
SpreadCycle shows slightly more
distortion at >1.4A RMS
StealthChop or SpreadCycle
(+) Good
50mA to 2A RMS
While the RDSon based measurements bring benefits concerning cost and size of the driver, it gives
slightly less precise coil current regulation when compared to external sense resistors. The internal
sense resistors have a certain temperature dependence, which is automatically compensated by the
driver IC. However, for high current motors, a temperature gradient between the ICs internal sense
resistors and the compensation circuit will lead to an initial current overshoot of some 10% during
driver IC heat up. While this phenomenon shows for roughly a second, it might even be beneficial to
enable increased torque during initial motor acceleration.
PRINCIPLE OF OPERATION
A reference current into the VREF pin is used as reference for the motor current. In order to realize a
certain current, a single resistor (RREF) can be connected between 5VOUT and VREF (pls. refer the table
for the choice of the resistor). VREF input resistance is about 0.45kOhm. The resulting current into VREF
is amplified 3000 times. Thus, a current of 0.33mA yields a motor current of 1.0A peak, or 0.7A RMS. For
calculation of the reference resistor, the internal resistance of VREF needs to be considered additionally.
CHOICE OF RREF FOR OPERATION WITHOUT SENSE RESISTORS
RREF [Ω]
6k2
6k8
7k5
8k2
9k1
10k
12k
15k
18k
22k
27k
33k
Peak current [A]
(CS=31, vsense=0)
2.26
1.92
1.76
1.63
1.49
1.36
1.15
0.94
0.79
0.65
0.60
0.54
www.trinamic.com
RMS current [A]
(CS=31, vsense=0)
1.59
1.35
1.24
1.15
1.05
0.96
0.81
0.66
0.55
0.45
0.42
0.38
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
54
vsense=1 allows a lower peak current setting of about 55% of the value yielded with vsense=0 (as
specified by VSRTH / VSRTL).
In RDSon measurement mode, connect the BRA and BRB pins to GND using the shortest possible path
(i.e. shortest possible PCB path). RDSon based measurement gives best results when combined with
StealthChop. When using SpreadCycle with RDSon based current measurement, slightly asymmetric
current measurement for positive currents (on phase) and negative currents (fast decay phase) may
result in chopper noise. This especially occurs at high die temperature and increased motor current.
Note
The absolute current levels achieved with RDSon based current sensing may depend on PCB layout
exactly like with external sense resistors, because trace resistance on BR pins will add to the effective
sense resistance. Therefore, we recommend to measure and calibrate the current setting within the
application.
Thumb rule
RDSon based current sensing works best for motors with up to 1.4A RMS current. The best results are
yielded with StealthChop operation in combination with RDSon based current sensing.
For most precise current control and for best results with SpreadCycle, it is recommended to use external
1% sense resistors rather than RDSon based current control.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
55
11 StallGuard4 Load Measurement
UART
StallGuard4 provides an accurate measurement of the load on the motor. It is developed for operation
in conjunction with StealthChop. StallGuard can be used for stall detection as well as other uses at
loads below those which stall the motor, such as CoolStep load-adaptive current reduction. The
StallGuard4 measurement value changes linearly over a wide range of load, velocity, and current
settings, as shown in Figure 11.1. When approaching maximum motor load, the value goes down to a
motor-specific lower value. This corresponds to a load angle of 90° between the magnetic field of the
coils and magnets in the rotor. This also is the most energy-efficient point of operation for the motor.
500
StallGuard4 reading
SG_RESULT
450
Start value depends
on motor, velocity
and operating current
400
350
SG_RESULT reaches compare
value and indicates danger of
stall. This point is set by
stallGuard threshold value
SGTHRS.
300
100% load value depends on
motor, operating current and
velocity
250
200
Stall detection
150
threshold SGTHRS*2
high 100
Stall Output
low 50
0
Motor stalls above this point.
Load angle exceeds 90° and
available torque sinks.
10
20
30
40
50
60
70
80
90
100
motor load
(% max. torque)
Figure 11.1 Function principle of StallGuard4
Parameter
SGTHRS
Description
Setting
This value controls the StallGuard4 threshold level 0… 255
for stall detection. It compensates for motor
specific characteristics and controls sensitivity. A
higher value gives a higher sensitivity. A higher
value makes StallGuard4 more sensitive and
requires less torque to indicate a stall.
Comment
The double of this value is
compared to SG_RESULT.
The stall output becomes
active if SG_RESULT fall
below this value.
Status word
SG_RESULT
Description
Range
This is the StallGuard4 result. A higher reading 0… 510
indicates less mechanical load. A lower reading
indicates a higher load and thus a higher load
angle.
Comment
Low value: highest load
High value: high load
In order to use StallGuard4, check the sensitivity of the motor at border conditions.
11.1 StallGuard4 vs. StallGuard2
StallGuard4 is optimized for operation with StealthChop, its predecessor StallGuard2 works with
SpreadCycle. The function is similar: Both deliver a load value, going from a high value at low load, to
a low value at high load. While StallGuard2 becomes tuned to show a “0”-reading for stall detection,
StallGuard4 uses a comparison-value to trigger stall detection, rather than shifting SG_RESULT itself.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
56
11.2 Tuning StallGuard4
The StallGuard4 value SG_RESULT is affected by motor-specific characteristics and application-specific
demands on load, coil current, and velocity. Therefore, the easiest way to tune the StallGuard4 threshold
SGTHRS for a specific motor type and operating conditions is interactive tuning in the actual application.
INITIAL PROCEDURE FOR TUNING STALLGUARD SGTHRS
1.
2.
3.
4.
Operate the motor at the normal operation velocity for your application and monitor SG_RESULT.
Apply slowly increasing mechanical load to the motor. Check the lowest value of SG_RESULT before
the motor stalls. Use this value as starting value for SGTHRS (apply half of the value).
Now monitor the StallGuard output signal via DIAG output (configure properly, also set TCOOLTHRS
to match the lower velocity limit for operation) and stop the motor when a pulse is seen on the
respective output. Make sure, that the motor is safely stopped whenever it is stalled. Increase
SGTHRS if the motor becomes stopped before a stall occurs.
The optimum setting is reached when a stall is safely detected and leads to a pulse at DIAG in the
moment where the stall occurs. SGTHRS in most cases can be tuned for a certain motion velocity
or a velocity range. Make sure, that the setting works reliable in a certain range (e.g. 80% to 120%
of desired velocity) and also under extreme motor conditions (lowest and highest applicable
temperature).
DIAG is pulsed by StallGuard, when SG_RESULT falls below SGTHRS. It is only enabled in StealthChop
mode, and when TCOOLTHRS ≥ TSTEP > TPWMTHRS
The external motion controller should react to a single pulse by stopping the motor if desired. Set
TCOOLTHRS to match the lower velocity threshold where StallGuard delivers a good result.
SG_RESULT measurement has a high resolution, and there are a few ways to enhance its accuracy, as
described in the following sections.
11.3 StallGuard4 Update Rate
The StallGuard4 measurement value SG_RESULT is updated with each full step of the motor. This is
enough to safely detect a stall, because a stall always means the loss of four full steps.
11.4 Detecting a Motor Stall
To safely detect a motor stall, the stall threshold must be determined using a specific SGTHRS setting
and a specific motor velocity or velocity range. Further, the motor current setting has a certain influence
and should not be modified, once optimum values are determined. Therefore, the maximum load needs
to be determined the motor can drive without stalling. At the same time, monitor SG_RESULT at this
load. The stall threshold should be a value safely within the operating limits, to allow for parameter
stray. More refined evaluation may also react to a change of SG_RESULT rather than comparing to a
fixed threshold. This will rule out certain effects which influence the absolute value.
11.5 Limits of StallGuard4 Operation
StallGuard4 does not operate reliably at extreme motor velocities: Very low motor velocities (for many
motors, less than one revolution per second) generate a low back EMF and make the measurement
unstable and dependent on environment conditions (temperature, etc.). Other conditions will also lead
to a poor response of the measurement value SG_RESULT to the motor load. Very high motor velocities,
in which the full sinusoidal current is not driven into the motor coils also leads to poor response. These
velocities are typically characterized by the motor back EMF exceeding the supply voltage.
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TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
57
12 CoolStep Operation
UART
CoolStep is an automatic smart energy optimization for stepper motors based on the motor mechanical
load, making them “green”.
12.1 User Benefits
Energy efficiency
Motor generates less heat
Less cooling infrastructure
Cheaper motor
–
–
–
–
consumption decreased up to 75%
improved mechanical precision
for motor and driver
does the job!
CoolStep allows substantial energy savings, especially for motors which see varying loads or operate
at a high duty cycle. Because a stepper motor application needs to work with a torque reserve of 30%
to 50%, even a constant-load application allows significant energy savings because CoolStep
automatically enables torque reserve when required. Reducing power consumption keeps the system
cooler, increases motor life, and allows reducing cost in the power supply and cooling components.
Reducing motor current by half results in reducing power by a factor of four.
12.2 Setting up for CoolStep
CoolStep is controlled by several parameters, but two are critical for understanding how it works:
Parameter
Description
SEMIN
4-bit unsigned integer that sets a lower threshold. 0
If SG_RESULT goes below this threshold, CoolStep 1…15
increases the current to both coils. The 4-bit SEMIN
value is scaled by 32 to cover the lower half of the
range of the 10-bit SG value. (The name of this
parameter is derived from SmartEnergy, which is an
earlier name for CoolStep.)
4-bit unsigned integer that controls an upper 0…15
threshold. If SG is sampled equal to or above this
threshold enough times, CoolStep decreases the
current to both coils. The upper threshold is (SEMIN
+ SEMAX + 1)*32.
SEMAX
Figure
-
Range
Comment
disable CoolStep
threshold is SEMIN*32
Once SGTHRS has been
determined, use
1/16*SGTHRS+1
as a starting point for
SEMIN.
threshold is
(SEMIN+SEMAX+1)*32
0 to 2 recommended
12.1 shows the operating regions of CoolStep:
The black line represents the SG_RESULT measurement value.
The blue line represents the mechanical load applied to the motor.
The red line represents the current into the motor coils.
When the load increases, SG_RESULT falls below SEMIN, and CoolStep increases the current. When the
load decreases, SG_RESULT rises above (SEMIN + SEMAX + 1) * 32, and the current is reduced.
www.trinamic.com
stallGuard2
reading
mechanical load
58
motor current
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
current setting I_RUN
(upper limit)
motor current reduction area
SEMAX+SEMIN+1
SEMIN
½ or ¼ I_RUN
(lower limit)
motor current increment area
0=maximum load
load angle optimized
Zeit
slow current reduction due
to reduced motor load
load
angle
optimized
current increment due to
increased load
stall possible
load angle optimized
Figure 12.1 CoolStep adapts motor current to the load
Five more parameters control CoolStep and one status value is returned:
Parameter
SEUP
SEDN
SEIMIN
TCOOLTHRS
TPWMTHRS
Status
word
CSACTUAL
Description
Range
Sets the current increment step. The current 0…3
becomes incremented for each measured StallGuard
value below the lower threshold.
Sets the number of StallGuard readings above the 0…3
upper threshold necessary for each current
decrement of the motor current.
Sets the lower motor current limit for CoolStep
operation by scaling the IRUN current setting.
Operate well above the minimum motor current as
determined for StealthChop current regulation.
Lower velocity threshold for switching on CoolStep
and stall output. Below this velocity CoolStep
becomes disabled (not used in STEP/DIR mode).
Adapt to the lower limit of the velocity range where
StallGuard gives a stable result.
Upper velocity threshold value for CoolStep and
stop on stall. Above this velocity the driver switches
to SpreadCycle. This also disables CoolStep and
StallGuard.
Description
0
1
1…
2^20-1
1…
2^20-1
Range
This status value provides the actual motor current 0…31
scale as controlled by CoolStep. The value goes up
to the IRUN value and down to the portion of IRUN
as specified by SEIMIN.
www.trinamic.com
Comment
step width is
1, 2, 4, 8
number of StallGuard
measurements per
decrement:
32, 8, 2, 1
0: 1/2 of IRUN
Attention: use IRUN≥10
1: 1/4 of IRUN
Attention: use IRUN≥20
Specifies lower CoolStep
velocity by comparing
the threshold value to
TSTEP
This setting typically is
used during chopper
mode configuration,
only.
Comment
1/32, 2/32, … 32/32
TMC2226 DATASHEET (Rev. 1.06 / 2020-MAY-18)
59
12.3 Tuning CoolStep
CoolStep uses SG_RESULT to operate the motor near the optimum load angle of +90°. The basic setting
to be tuned is SEMIN. Set SEMIN to a value which safely activates CoolStep current increment before
the motor stalls. In case SGTHRS has been tuned before, a lower starting value is
SEMIN = 1+SGTHRS/16.
The current increment speed is specified in SEUP, and the current decrement speed is specified in SEDN.
They can be tuned separately because they are triggered by different events that may need different
responses. The encodings for these parameters allow the coil currents to be increased much more
quickly than decreased, because crossing the lower threshold is a more serious event that may require
a faster response. If the response is too slow, the motor may stall. In contrast, a slow response to
crossing the upper threshold does not risk anything more serious than missing an opportunity to save
power.
CoolStep operates between limits controlled by the current scale parameter IRUN and the seimin bit.
Attention
When CoolStep increases motor current, spurious detection of motor stall may occur. For best results,
disable CoolStep during StallGuard based homing.
In case StallGuard is desired in combination with CoolStep, try increasing coolStep lower threshold
SEMIN as required.
12.3.1 Response Time
For fast response to increasing motor load, use a high current increment step SEUP. If the motor load
changes slowly, a lower current increment step can be used to avoid motor oscillations.
Hint
The most common and most beneficial use is to adapt CoolStep for operation at the typical system
target operation velocity and to set the velocity thresholds according. As acceleration and decelerations
normally shall be quick, they will require the full motor current, while they have only a small
contribution to overall power consumption due to their short duration.
12.3.2 Low Velocity and Standby Operation
Because CoolStep is not able to measure the motor load in standstill and at very low RPM, a lower
velocity threshold is provided for enabling CoolStep. It should be set to an application specific default
value. Below this threshold the normal current setting via IRUN respectively IHOLD is valid.
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13 STEP/DIR Interface
The STEP and DIR inputs provide a simple, standard interface compatible with many existing motion
controllers. The MicroPlyer step pulse interpolator brings the smooth motor operation of high-resolution
microstepping to applications originally designed for coarser stepping.
13.1 Timing
Figure 13.1 shows the timing parameters for the STEP and DIR signals, and the table below gives their
specifications. Only rising edges are active. STEP and DIR are sampled and synchronized to the system
clock. An internal analog filter removes glitches on the signals, such as those caused by long PCB traces.
If the signal source is far from the chip, and especially if the signals are carried on cables, the signals
should be filtered or differentially transmitted.
+VCC_IO
DIR
SchmittTrigger
tSH
tDSU
tSL
tDSH
STEP
or DIR
Input
STEP
83k
0.56 VCC_IO
0.44 VCC_IO
Internal
Signal
Active edge
(DEDGE=0)
Active edge
(DEDGE=0)
C
Input filter
R*C = 20ns +-30%
Figure 13.1 STEP and DIR timing, Input pin filter
STEP and DIR interface timing
AC-Characteristics
clock period is tCLK
Parameter
step frequency (at maximum
microstep resolution)
fullstep frequency
STEP input minimum low time
Symbol
fSTEP
STEP input minimum high time
tSH
DIR to STEP setup time
DIR after STEP hold time
STEP and DIR spike filtering time
*)
STEP and DIR sampling relative
to rising CLK input
tDSU
tDSH
Conditions
fFS
tSL
tFILTSD
tSDCLKHI
Min
Typ
Max
½ fCLK
max(tFILTSD,
tCLK+20)
max(tFILTSD,
tCLK+20)
100
ns
100
ns
20
ns
ns
ns
fCLK/512
rising and falling
edge
before rising edge
of CLK input
20
20
13
30
tFILTSD
*) These values are valid with full input logic level swing, only. Asymmetric logic levels will increase
filtering delay tFILTSD, due to an internal input RC filter.
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Unit
ns
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13.2 Changing Resolution
The TMC2226 includes an internal microstep table with 1024 sine wave entries to generate sinusoidal
motor coil currents. These 1024 entries correspond to one electrical revolution or four fullsteps. The
microstep resolution setting determines the step width taken within the table. Depending on the DIR
input, the microstep counter is increased (DIR=0) or decreased (DIR=1) with each STEP pulse by the step
width. The microstep resolution determines the increment respectively the decrement. At maximum
resolution, the sequencer advances one step for each step pulse. At half resolution, it advances two
steps. Increment is up to 256 steps for fullstepping. The sequencer has special provision to allow
seamless switching between different microstep rates at any time. When switching to a lower microstep
resolution, it calculates the nearest step within the target resolution and reads the current vector at
that position. This behavior especially is important for low resolutions like fullstep and halfstep, because
any failure in the step sequence would lead to asymmetrical run when comparing a motor running
clockwise and counterclockwise.
EXAMPLES:
Fullstep:
Cycles through table positions: 128, 384, 640 and 896 (45°, 135°, 225° and 315° electrical
position, both coils on at identical current). The coil current in each position corresponds
to the RMS-Value (0.71 * amplitude). Step size is 256 (90° electrical)
Half step:
The first table position is 64 (22.5° electrical), Step size is 128 (45° steps)
Quarter step: The first table position is 32 (90°/8=11.25° electrical), Step size is 64 (22.5° steps)
This way equidistant steps result and they are identical in both rotation directions. Some older drivers
also use zero current (table entry 0, 0°) as well as full current (90°) within the step tables. This kind of
stepping is avoided because it provides less torque and has a worse power dissipation in driver and
motor.
Step position
Half step 0
Full step 0
Half step 1
Half step 2
Full step 1
Half step 3
Half step 4
Full step 2
Half step 5
Half step 6
Full step 3
Half step 7
table position
64
128
192
320
384
448
576
640
704
832
896
960
current coil A
38.3%
70.7%
92.4%
92.4%
70.7%
38.3%
-38.3%
-70.7%
-92.4%
-92.4%
-70.7%
-38.3%
current coil B
92.4%
70.7%
38.3%
-38.3%
-70.7%
-92.4%
-92.4%
-70.7%
-38.3%
38.3%
70.7%
92.4%
See chapter 3.4 for resolution settings available in stand-alone mode.
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13.3 MicroPlyer Step Interpolator and Stand Still Detection
For each active edge on STEP, MicroPlyer produces microsteps at 256x resolution, as shown in Figure
13.2. It interpolates the time in between of two step impulses at the step input based on the last step
interval. This way, from 2 microsteps (128 microstep to 256 microstep interpolation) up to 256 microsteps
(full step input to 256 microsteps) are driven for a single step pulse.
The step rate for the interpolated 2 to 256 microsteps is determined by measuring the time interval of
the previous step period and dividing it into up to 256 equal parts. The maximum time between two
microsteps corresponds to 220 (roughly one million system clock cycles), for an even distribution of 256
microsteps. At 12 MHz system clock frequency, this results in a minimum step input frequency of roughly
12 Hz for MicroPlyer operation. A lower step rate causes a standstill event to be detected. At that
frequency, microsteps occur at a rate of (system clock frequency)/2 16 ~ 256 Hz. When a stand still is
detected, the driver automatically begins standby current reduction if selected by pin PDN.
Active edge
(dedge=0)
Active edge
(dedge=0)
Active edge
(dedge=0)
Active edge
(dedge=0)
Attention
MicroPlyer only works perfectly with a jitter-free STEP frequency.
STEP
Interpolated
microstep
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
Motor
angle
2^20 tCLK
STANDSTILL
(stst) active
Figure 13.2 MicroPlyer microstep interpolation with rising STEP frequency (Example: 16 to 256)
In Figure 13.2, the first STEP cycle is long enough to set the stst bit standstill. Detection of standstill
will enable the standby current reduction. This bit is cleared on the next STEP active edge. Then, the
external STEP frequency increases. After one cycle at the higher rate MicroPlyer adapts the interpolated
microstep rate to the higher frequency. During the last cycle at the slower rate, MicroPlyer did not
generate all 16 microsteps, so there is a small jump in motor angle between the first and second cycles
at the higher rate.
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13.4 Index Output
An active INDEX output signals that the sine curve of motor coil A is at its positive zero transition. This
correlates to the zero point of the microstep sequence. Usually, the cosine curve of coil B is at its
maximum at the same time. Thus, the index signal is active once within each electrical period, and
corresponds to a defined position of the motor within a sequence of four fullsteps. The INDEX output
this way allows the detection of a certain microstep pattern, and thus helps to detect a position with
more precision than a stop switch can do.
Current
COIL A
0
COIL B
Time
INDEX
Current
Time
STEPS
Time
Figure 13.3 Index signal at positive zero transition of the coil A sine curve
Hint
The index output allows precise detection of the microstep position within one electrical wave, i.e.
within a range of four fullsteps. With this, homing accuracy and reproducibility can be enhanced to
microstep accuracy, even when using an inexpensive home switch.
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14 Internal Step Pulse Generator
UART
The TMC22xx family integrates a high-resolution step pulse generator, allowing motor motion via the
UART interface. However, no velocity ramping is provided. Ramping is not required, if the target motion
velocity is smaller than the start & stop frequency of the motor. For higher velocities, ramp up the
frequency in small steps to accelerate the motor, and ramp down again to decelerate the motor. Figure
14.1 shows an example motion profile ramping up the motion velocity in discrete steps. Choose the
ramp velocity steps considerably smaller than the maximum start velocity of the motor, because motor
torque drops at higher velocity, and motor load at higher velocity typically increases.
motor
stop
v
acceleration
constant velocity
deceleration
Th
eo
re
t
ica
l
pr
of
ile
Target Velocity
Stop velocity
Start velocity
0
t
VACTUAL
Figure 14.1 Software generated motion profile
PARAMETER VS. UNITS
Parameter / Symbol
fCLK[Hz]
Unit
[Hz]
µstep velocity v[Hz]
µsteps / s
USC microstep count
counts
rotations per second v[rps]
rotations / s
TSTEP, TPWMTHRS
-
VACTUAL
Two’s complement
signed internal
velocity
calculation / description / comment
clock frequency of the TMC2226 in [Hz]
v[Hz] = VACTUAL[2226] * ( fCLK[Hz]/2 / 2^23 )
With internal oscillator:
v[Hz] = VACTUAL[2226] * 0.715Hz
microstep resolution in number of microsteps
(i.e. the number of microsteps between two
fullsteps – normally 256)
v[rps] = v[Hz] / USC / FSC
FSC: motor fullsteps per rotation, e.g. 200
TSTEP = fCLK / fSTEP
The time reference for velocity threshold is
referred to the actual microstep frequency of the
step input respectively velocity v[Hz].
VACTUAL[2226] = ( fCLK[Hz]/2 / 2^23 ) / v[Hz]
With internal oscillator:
VACTUAL[2226] = 0.715Hz / v[Hz]
Hint
To monitor internal step pulse execution, program the INDEX output to provide step pulses
(GCONF.index_step). It toggles upon each step. Use a timer input on your CPU to count pulses.
Alternatively, regularly poll MSCNT to grasp steps done in the previous polling interval. It wraps around
from 1023 to 0.
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15 Driver Diagnostic Flags
The TMC2226 drivers supply a complete set of diagnostic and protection capabilities, like short to GND
protection, short to VS protection and undervoltage detection. A detection of an open load condition
allows testing if a motor coil connection is interrupted. See the DRV_STATUS table for details.
15.1 Temperature Measurement
The driver integrates a four-level temperature sensor (pre-warning and thermal shutdown) for
diagnostics and for protection of the IC against excess heat. The thresholds can be adapted by UART or
OTP programming. Heat is mainly generated by the motor driver stages, and, at increased voltage, by
the internal voltage regulator. Most critical situations, where the driver MOSFETs could be overheated,
are avoided by the short to GND protection. For many applications, the overtemperature pre-warning
will indicate an abnormal operation situation and can be used to initiate user warning or power
reduction measures like motor current reduction. The thermal shutdown is just an emergency measure
and temperature rising to the shutdown level should be prevented by design.
TEMPERATURE THRESHOLDS
Overtemperature
Setting
143°C
(OTPW: 120°C)
150°C
(OTPW:
120°C or 143°C)
157°C
(OTPW: 143°C)
Comment
Default setting. This setting is safest to switch off the driver stage before the IC
can be destroyed by overheating. On a large PCB, the power MOSFETs reach roughly
150°C peak temperature when the temperature detector is triggered with this
setting. This is a trip typical point for overtemperature shut down. The
overtemperature pre-warning threshold of 120°C gives lots of headroom to react
to high driver temperature, e.g. by reducing motor current.
Optional setting (OTP or UART). For small PCBs with high thermal resistance
between PCB and environment, this setting provides some additional headroom.
The small PCB shows less temperature difference between the MOSFETs and the
sensor.
Optional setting (UART). For applications, where a stop of the motor cannot be
tolerated, this setting provides highest headroom, e.g. at high environment
temperature ratings. Using the 143°C overtemperature pre-warning to reduce motor
current ensures that the motor is not switched off by the thermal threshold.
Attention
Overtemperature protection cannot in all cases avoid thermal destruction of the IC. In case the rated
motor current is exceed, e.g. by operating a motor in StealthChop with wrong parameters, or with
automatic tuning parameters not fitting the operating conditions, excess heat generation can quickly
heat up the driver before the overtemperature sensor can react. This is due to a delay in heat conduction
over the IC die.
After triggering the overtemperature sensor (ot flag), the driver remains switched off until the system
temperature falls below the pre-warning level (otpw) to avoid continuous heating to the shutdown
level.
15.2 Short Protection
The TMC2226 power stages are protected against a short circuit condition by an additional measurement
of the current flowing through each of the power stage MOSFETs. This is important, as most short
circuit conditions result from a motor cable insulation defect, e.g. when touching the conducting parts
connected to the system ground. The short detection is protected against spurious triggering, e.g. by
ESD discharges, by retrying three times before switching off the motor.
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Once a short condition is safely detected, the corresponding driver bridge (A or B) becomes switched
off, and the s2ga or s2gb flag, respectively s2vsa or s2vsb becomes set. In order to restart the motor,
disable and re-enable the driver. Note, that short protection cannot protect the system and the power
stages for all possible short events, as a short event is rather undefined and a complex network of
external components may be involved. Therefore, short circuits should basically be avoided.
15.3 Open Load Diagnostics
UART
Interrupted cables are a common cause for systems failing, e.g. when connectors are not firmly plugged.
The TMC2226 detects open load conditions by checking, if it can reach the desired motor coil current.
This way, also undervoltage conditions, high motor velocity settings or short and overtemperature
conditions may cause triggering of the open load flag, and inform the user, that motor torque may
suffer. In motor stand still, open load cannot always be measured, as the coils might eventually have
zero current.
Open load detection is provided for system debugging.
In order to safely detect an interrupted coil connection, read out the open load flags at low or nominal
motor velocity operation, only. If possible, use SpreadCycle for testing, as it provides the most accurate
test. However, the ola and olb flags have just informative character and do not cause any action of the
driver.
15.4 Diagnostic Output
The diagnostic output DIAG and the index output INDEX provide important status information. An active
DIAG output shows that the driver cannot work normally, or that a motor stall is detected, when
StallGuard is enabled. The INDEX output signals the microstep counter zero position, to allow referencing
(homing) a drive to a certain current pattern. The function set of the INDEX output can be modified by
UART. Figure 15.1 shows the available signals and control bits.
StallDetection
(gated by TPWMTHRS
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