TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
1
TMC246/B – DATA SHEET
High current microstep stepper motor driver
with stallGuard™, protection / diagnostics and
SPI Interface
®
TRINAMIC Motion Control GmbH & Co KG
Hamburg, Germany
WWW.TRINAMIC.COM
Features
The TMC246 / TMC246A / TMC246B (1) is a dual full bridge driver IC for bipolar stepper motor control
applications. The integrated unique sensorless stall detection (pat. pend.) stallGuard™ makes it a
good choice for applications, where a reference point is needed, but where a switch is not desired. Its
ability to predict an overload makes the TMC246 an optimum choice for drives, where a high reliability
is desired. The TMC246 is realized in a HVCMOS technology combined with Low-RDS-ON high
efficiency MOSFETs (pat. pend.). It allows driving a coil current of up to 1500mA even at high
environment temperatures. Its low current consumption and high efficiency together with the miniature
package make it a perfect solution for embedded motion control and for battery powered devices.
Internal DACs allow microstepping as well as smart current control. The device can be controlled by a
i
serial interface (SPI™ ) or by analog / digital input signals. Short circuit, temperature, undervoltage and
overvoltage protection are integrated.
Sensorless stall detection stallGuard™ and load measurement integrated
Control via SPI with easy-to-use 12 bit protocol or external analog / digital signals
Short circuit, overvoltage and over temperature protection integrated
Status flags for overcurrent, open load, over temperature, temperature pre-warning, undervoltage
Integrated 4 bit DACs allow up to 16 times microstepping via SPI (can be expanded to 64
microsteps)
Any resolution via analog control
Mixed decay feature for smooth motor operation
Slope control user programmable to reduce electromagnetic emissions
Chopper frequency programmable via a single capacitor or external clock
Current control allows cool motor and driver operation
7V to 34V motor supply voltage (A-type)
Up to 1500mA output current and more than 800mA at 105°C
3.3V or 5V operation for digital part
Low power dissipation via low RDS-ON power stage
Standby and shutdown mode available
(1) The term TMC246 in this datasheet always refers to the TMC246B, TMC246A and the TMC246.
The major differences in the older TMC246 are explicitly marked with “non-A-type”. The TMC246A
brings a number of enhancements and is fully backward compatible to the TMC246. The latest
revision TMC246B is 100% compatible to the TMC246A.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
2
FEATURES.............................................................................................................................................. 1
PINNING .................................................................................................................................................. 5
PACKAGE CODES.................................................................................................................................... 5
PQFP44 DIMENSIONS ............................................................................................................................ 6
APPLICATION CIRCUIT / BLOCK DIAGRAM ....................................................................................... 7
PIN FUNCTIONS ...................................................................................................................................... 7
LAYOUT CONSIDERATIONS ................................................................................................................ 8
CONTROL VIA THE SPI INTERFACE ................................................................................................... 9
SERIAL DATA WORD TRANSMITTED TO TMC246....................................................................................... 9
SERIAL DATA WORD TRANSMITTED FROM TMC246 .................................................................................. 9
TYPICAL WINDING CURRENT VALUES ..................................................................................................... 10
BASE CURRENT CONTROL VIA INA AND INB IN SPI MODE ....................................................................... 10
CONTROLLING THE POWER DOWN MODE VIA THE SPI INTERFACE ........................................................... 10
OPEN LOAD DETECTION ........................................................................................................................ 11
STANDBY AND SHUTDOWN MODE........................................................................................................... 11
POWER SAVING .................................................................................................................................... 11
STALL DETECTION ............................................................................................................................. 12
USING THE SENSORLESS LOAD MEASUREMENT ...................................................................................... 12
IMPLEMENTING SENSORLESS STALL DETECTION ..................................................................................... 12
PROTECTION FUNCTIONS ................................................................................................................. 13
OVERCURRENT PROTECTION AND DIAGNOSIS ........................................................................................ 13
OVERTEMPERATURE PROTECTION AND DIAGNOSIS................................................................................. 13
OVERVOLTAGE PROTECTION AND ENN PIN BEHAVIOR ............................................................................ 13
CHOPPER PRINCIPLE ......................................................................................................................... 14
CHOPPER CYCLE / USING THE MIXED DECAY FEATURE............................................................................ 14
ADAPTING THE SINE WAVE FOR SMOOTH MOTOR OPERATION .................................................................. 15
BLANK TIME ......................................................................................................................................... 15
BLANK TIME SETTINGS .......................................................................................................................... 15
CLASSICAL NON-SPI CONTROL MODE (STAND ALONE MODE) .................................................. 16
PIN FUNCTIONS IN STAND ALONE MODE.................................................................................................. 16
INPUT SIGNALS FOR MICROSTEP CONTROL IN STAND ALONE MODE .......................................................... 16
CALCULATION OF THE EXTERNAL COMPONENTS ....................................................................... 17
SENSE RESISTOR ................................................................................................................................. 17
EXAMPLES FOR SENSE RESISTOR SETTINGS .......................................................................................... 17
HIGH SIDE OVERCURRENT DETECTION RESISTOR RSH ............................................................................ 17
MAKING THE CIRCUIT SHORT CIRCUIT PROOF ......................................................................................... 18
OSCILLATOR CAPACITOR ...................................................................................................................... 19
TABLE OF OSCILLATOR FREQUENCIES.................................................................................................... 19
PULLUP RESISTORS ON UNUSED INPUTS ................................................................................................ 19
POWER SUPPLY SEQUENCING CONSIDERATIONS .................................................................................... 19
SLOPE CONTROL RESISTOR ................................................................................................................. 20
EXAMPLE FOR SLOPE SETTINGS ............................................................................................................ 20
ABSOLUTE MAXIMUM RATINGS ....................................................................................................... 21
ELECTRICAL CHARACTERISTICS ..................................................................................................... 21
OPERATIONAL RANGE .......................................................................................................................... 21
DC CHARACTERISTICS ......................................................................................................................... 22
AC CHARACTERISTICS ......................................................................................................................... 23
THERMAL PROTECTION......................................................................................................................... 24
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
3
THERMAL CHARACTERISTICS ................................................................................................................ 24
TYPICAL POWER DISSIPATION AT HIGH LOAD / HIGH TEMPERATURE ........................................................ 24
SPI INTERFACE TIMING ...................................................................................................................... 25
PROPAGATION TIMES ........................................................................................................................... 25
USING THE SPI INTERFACE ................................................................................................................... 25
SPI FILTER .......................................................................................................................................... 25
ESD PROTECTION ............................................................................................................................... 26
APPLICATION NOTE: EXTENDING THE MICROSTEP RESOLUTION ............................................. 27
DOCUMENTATION REVISION ............................................................................................................ 28
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
Life support policy
TRINAMIC Motion Control GmbH & Co KG does not
authorize or warrant any of its products for use in life
support systems, without the specific written consent
of TRINAMIC Motion Control GmbH & Co KG.
Life support systems are equipment intended to
support or sustain life, and whose failure to perform,
when properly used in accordance with instructions
provided, can be reasonably expected to result in
personal injury or death.
© TRINAMIC Motion Control GmbH & Co KG 2005
Information given in this data sheet is believed to be
accurate and reliable. However no responsibility is
assumed for the consequences of its use nor for any
infringement of patents or other rights of third parties,
which may result from its use.
Specifications subject to change without notice.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
4
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
5
ANN
AGND
SLP
INA
INB
VCC
GND
-
-
VS
VT
-
44
43
42
41
40
39
38
37
36
35
34
Pinning
1
33
2
32
3
31
4
30
5
29
OA1
VSA
OB1
TMC 246 / 236A
QFP44
OA2
6
7
VSB
OB2
28
27
OA1
BRA
BL2
OB1
8
26
9
25
10
24
11
23
13
14
15
16
17
18
19
20
21
22
SDO
SDI
SCK
GND
CSN
ENN
SPE
BL1
SRB
SRA
12
OB2
OSC
OA2
BRB
Package codes
Type
TMC246A
TMC246
Package
PQFP44
PQFP44
Temperature range
automotive (1)
automotive (1)
Lead free (ROHS)
Yes
From date code 30/04
Code/marking
TMC246A-PA
TMC246-PA
(1) ICs are not tested according to automotive standards, but are usable within the complete
automotive temperature range.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
E
F
G
PQFP44 Dimensions
I
D
C
REF
A
C
D
E
F
G
H
I
K
L
MIN.
MAX.
12
10
1
0.09
0.05
0.30
0.45
1.6
0.2
0.15
0.45
0.75
0.8
0
0.08
A
All dimensions are in mm.
L: Co-planarity of pins
H
K
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
6
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
7
Application Circuit / Block Diagram
+VM
BL1
BL2
220nF
VS
TMC246
OSC
100µF
RSH
VT
VSA
OSC
Current Controlled
Gate Drivers
Undervoltage
VCC
PWM-CTRL
+VCC
1nF
100nF
Temperature
P
P
OA1
OA2
N
Coil A
N
BRA
SDI
[PHB]
SDO
Parallel
Control
[ERR]
CSN
0
Load
mesurement
[PHA]
Control & Diagnosis
SCK
SPIInterface
RS
[MDBN]
DAC
4
SRA
1
INA
REFSEL
VREF
DAC
INB
4
1
0
SRB
RS
PWM-CTRL
Current Controlled
Gate Drivers
BRB
ENN
VCC/2
REFSEL
N
N
OB1
OB2
P
Coil B
P
VSB
SPE
ANN
AGND
GND
SLP
[MDAN]
stand alone mode
RSLP
[...]: function in stand alone mode
Pin Functions
Pin
Function
Pin
Function
VS
Motor supply voltage
VT
VCC
3.0-5.5V supply voltage for analog
and logic circuits
Analog ground (Reference for SRA,
SRB, OSC, SLP, INA, INB, SLP)
Analog current control phase A
Clock input of serial interface
Data input of serial interface
Device enable (low active), and
overvoltage shutdown input
Enable analog current control via
INA and INB (low active)
Digital blank time select
Output of full-bridge A
Supply voltage for bridge A/B
GND
Short to GND detection comparator –
connect to VS if not used
Digital / Power ground
AGND
INA
SCK
SDI
ENN
ANN
BL1, BL2
OA1, OA2
VSA, VSB
OSC
SLP
Oscillator capacitor or external clock
input for chopper
Analog current control input phase B
Data output of serial interface (tri-state)
Chip select input of serial interface
Enable SPI mode (high active). Tie to
GND for non-SPI applications
Slope control resistor.
SRA, SRB
OB1, OB2
BRA, BRB
Bridge A/B current sense resistor input
Output of full-bridge B
Bridge A/B sense resistor
INB
SDO
CSN
SPE
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
8
Layout Considerations
For optimal operation of the circuit a careful board layout is important, because of the combination of
high current chopper operation coupled with high accuracy threshold comparators. Please pay special
attention to a massive grounding. Depending on the required motor current, either a single massive
ground plane or a ground plane plus star connection of the power traces may be used. The schematic
shows how the high current paths can be routed separately, so that the chopper current does not flow
through the system’s GND-plane. Tie the TMC246’s AGND and GND to the GND plane. Additionally,
use enough filtering capacitors located near to the board’s power supply input and small ceramic
capacitors near to the power supply connections of the TMC246. Use low inductance sense resistors,
or add a ceramic capacitor in parallel to each resistor to avoid high voltage spikes. In some
applications it may become necessary to introduce additional RC-filtering into the VT and SRA / SRB
line, as shown in the schematic, to prevent spikes from triggering the short circuit protection or the
chopper comparator.
Be sure to connect all pins of the PQFP package for each of the double/quad output pins externally.
Each two of these output pins should be treated as if they were fused to a single wide pin (as shown in
the drawing). Each two pins are used as cooling fin for one of the eight integrated output power
transistors. Use massive motor current traces on all these pins and multiple vias, if the output trace is
changed to a different layer near the package.
A symmetrical layout on all of the OA and OB pins is required, to ensure proper heat dissipation on all
output transistors. Otherwise proper function of the thermal protection can not be guaranteed!
A multi-layer PCB shows superior thermal performance, because it allows usage of a massive GND
plane, which will act as a heat spreader. The heat will be coupled vertically from the output traces to
the GND plane, since vertical heat distribution in PCBs is quite effective. Heat dissipation can be
improved by attaching a heat sink to the package directly.
Please be aware, that long or thin traces to the sense resistors may add substantial resistance and
thus reduce output current. The same is valid for the high side shunt resistor. Use short and straight
traces to avoid parasitic inductivities, because these can generate large voltage spikes and EMV
problems.
optional
voltage divider
VS
RDIV
RSH
100nF
VT
+VM
100R
GND
VSA
TMC236/
TMC246
VSB
BRA
CVM
BRB
SRA
optional filter
100R
SRB
RSA
RSB
100R
3.3 10nF
AGND
GND
GNDPlane
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
9
Control via the SPI Interface
The SPI data word sets the current and polarity for both coils. By applying consecutive values,
describing a sine and a cosine wave, the motor can be driven in microsteps. Every microstep is
initiated by its own telegram. Please refer to the description of the analog mode for details on the
waveforms required. The SPI interface timing is described in the timing section. We recommend the
TMC428 to automatically generate the required telegrams and motor ramps for up to three motors.
Serial data word transmitted to TMC246
(MSB transmitted first)
Bit Name Function
Remark
11
MDA
mixed decay enable phase A
“1” = mixed decay
10
CA3
current bridge A.3
MSB
9
CA2
current bridge A.2
8
CA1
current bridge A.1
7
CA0
current bridge A.0
LSB
6
PHA
polarity bridge A
“0” = current flow from OA1 to OA2
5
MDB
mixed decay enable phase B
“1” = mixed decay
4
CB3
current bridge B.3
MSB
3
CB2
current bridge B.2
2
CB1
current bridge B.1
1
CB0
current bridge B.0
LSB
0
PHB
polarity bridge B
“0” = current flow from OB1 to OB2
Serial data word transmitted from TMC246
(MSB transmitted first)
Bit Name Function
Remark
11
LD2
load indicator bit 2
MSB
10
LD1
load indicator bit 1
9
LD0
load indicator bit 0
8
1
always “1”
7
OT
over temperature
6
OTPW temperature pre-warning
“1” = pre-warning temperature exceeded
5
UV
driver undervoltage
“1” = undervoltage on VS
4
OCHS
overcurrent high side
3 PWM cycles with overcurrent within 63 PWM cycles
3
OLB
open load bridge B
no PWM switch off for 14 oscillator cycles
2
OLA
open load bridge A
no PWM switch off for 14 oscillator cycles
1
OCB
overcurrent bridge B low side
3 PWM cycles with overcurrent within 63 PWM cycles
0
OCA
overcurrent bridge A low side
3 PWM cycles with overcurrent within 63 PWM cycles
LSB
“1” = chip off due to over temperature
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
10
Typical winding current values
Current setting
Percentage of
current
Typical trip voltage of the current sense comparator
(internal reference or analog input voltage of 2V is used)
0000
0%
0V
0001
6.7%
23 mV
0010
13.3%
45 mV
CA3..0 / CB3..0
...
(bridge continuously in slow decay condition)
...
1110
93.3%
317 mV
1111
100%
340 mV
The current values correspond to a standard 4 Bit DAC, where 100%=15/16. The contents of all
registers is cleared to “0” on power-on reset or disable via the ENN pin, bringing the chip to a low
power standby mode. All SPI inputs have Schmitt-Trigger function.
Base current control via INA and INB in SPI mode
In SPI mode, the IC can use an external reference voltage for each DAC. This allows the adaptation to
different motors. This mode is enabled by tying pin ANN to GND. A 2.0V input voltage gives full scale
current of 100%. In this case, the typical trip voltage of the current sense comparator is determined by
the input voltage and the DAC current setting (see table above) as follows:
VTRIP,A = 0.17 VINA “percentage SPI current setting A”
VTRIP,B = 0.17 VINB “percentage SPI current setting B”
A maximum of 3.0V VIN is possible. Multiply the percentage of base current setting and the DAC table
to get the overall coil current. It is advised to operate at a high base current setting, to reduce the
effects of noise voltages. This feature allows a high resolution setting of the required motor current
using an external DAC or PWM-DAC (see schematic for examples).
using PWM signal
8 level via R2R-DAC
2 level control
INA
µCPort .2
R1
R2
100K
51K
47K
100nF
10nF
100K
µCPort .1
51K
AGND
+VCC
µCPWM
INB
100K
µCPort .0
µCPort
51K
ANN
Controlling the power down mode via the SPI interface
Bit
Standard
function
Control
word
function
11
10
9
8
7
6
5
4
3
2
1
0
MxA CA3 CA2 CA1 CA0 PhA MxB CB3 CB2 CB1 CB0 PhB
-
0
0
0
0
-
-
0
0
0
0
-
Enable standby mode and
clear error flags
Programming current value “0000” for both coils at a time clears the overcurrent flags and switches the
TMC246 into a low current standby mode with coils switched off.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
11
Open load detection
Open load is signaled whenever there are more than 14 oscillator cycles without PWM switch off. Note
that open load detection is not possible while coil current is set to “0000”, because the chopper is off in
this condition. The open load flag will then always be read as inactive (“0”). During overcurrent and
undervoltage or over temperature conditions, the open load flags also become active!
Due to their principle, the open load flags not only signal an open load condition, but also a torque loss
of the motor, especially at high motor velocities. To detect only an interruption of the connection to the
motor, it is advised to evaluate the flags during stand still or during low velocities only (e.g. for the first
or last steps of a movement).
Standby and shutdown mode
The circuit can be put into a low power standby mode by the user, or, automatically goes to standby on
Vcc undervoltage conditions. Before entering standby mode, the TMC246 switches off all power driver
outputs. In standby mode the oscillator becomes disabled and the oscillator pin is held at a low state.
The standby mode is available via the interface in SPI-mode and via the ENN pin in non-SPI mode.
The shutdown mode even reduces supply current further. It can only be entered in SPI-mode by pulling
the ENN pin high. In shutdown additionally all internal reference voltages become switched off and the
SPI circuit is held in reset.
Power saving
The possibility to control the output current can dramatically save energy, reduce heat generation and
increase precision by reducing thermal stress on the motor and attached mechanical components. Just
reduce motor current during stand still: Even a slight reduction of the coil currents to 70% of the current
of the last step of the movement, halves power consumption! In typical applications a 50% current
reduction during stand still is reasonable.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
12
Stall Detection
Using the sensorless load measurement
The TMC246 provides a patented sensorless load measurement, which allows a digital read out of the
mechanical load on the motor via the serial interface. To get a readout value, just drive the motor using
sine commutation and mixed decay switched off. The load measurement then is available as a three
bit load indicator during normal motion of the motor. A higher mechanical load on the motor results in a
lower readout value. The value is updated once per fullstep.
The load detection is based on the motor’s back EMF, thus the level depends on several factors:
- Motor velocity: A higher velocity leads to a higher readout value
- Motor resonance: Motor resonances cause a high dynamic load on the motor, and thus
measurement may give unsatisfactory results.
- Motor acceleration: Acceleration phases also produce dynamic load on the motor.
- Mixed decay setting: For load measurement mixed decay has to be off for some time before
the zero crossing of the coil current. If mixed decay is used, and the mixed decay period is
extended towards the zero crossing, the load indicator value decreases.
Implementing sensorless stall detection
The sensorless stall detection typically is used, to detect the reference point without the usage of a
switch or photo interrupter. Therefore the actuator is driven to a mechanical stop, e.g. one end point in
a spindle type actuator. As soon as the stop is hit, the motor stalls. Without stall detection, this would
give an audible humming noise and vibrations, which could damage mechanics.
To get a reliable stall detection, follow these steps:
1. Choose a motor velocity for reference movement. Use a medium velocity which is far enough
away from mechanical resonance frequencies. In some applications even motor start / stop
frequency may be used. With this the motor can stop within one fullstep if a stall is detected.
2. Use a sine stepping pattern and switch off mixed decay (at least 1 to 3 microsteps before zero
crossing of the wave). Monitor the load indicator during movement. It should show a stable
readout value in the range 3 to 7 (LMOVE). If the readout is high (>5), the mixed decay portion
may be increased, if desired.
3. Choose a threshold value LSTALL between 0 and LMOVE - 1.
4. Monitor the load indicator during each reference search movement, as soon as the desired
velocity is reached. Readout is required at least once per fullstep. If the readout value at one
fullstep is below or equal to LSTALL, stop the motor. Attention: Do not read out the value within
one chopper period plus 8 microseconds after toggling one of the phase polarities!
5. If the motor stops during normal movement without hitting the mechanical stop, decrease
LSTALL. If the stall condition is not detected at once, when the motor stalls, increase LSTALL.
v(t)
a_
m
ax
v_max
t
load
indicator
acceleration
constant velocity
max
stall
LMOVE
LSTALL
stall threshold
min
t
acceleration
jerk
stall detected!
vibration
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
13
Protection Functions
Overcurrent protection and diagnosis
The TMC246 uses the current sense resistors on the low side to detect an overcurrent: Whenever a
voltage above 0.61V is detected, the PWM cycle is terminated at once and all transistors of the bridge
are switched off for the rest of the PWM cycle. The error counter is increased by one. If the error
counter reaches 3, the bridge remains switched off for 63 PWM cycles and the error flag is read as
“active”. The user can clear the error condition in advance by clearing the error flag. The error counter
is cleared, whenever there are more than 63 PWM cycles without overcurrent. There is one error
counter for each of the low side bridges, and one for the high side. The overcurrent detection is
inactive during the blank pulse time for each bridge, to suppress spikes which can occur during
switching.
The high side comparator detects a short to GND or an overcurrent, whenever the voltage between VS
and VT becomes higher than 0.15 V at any time, except for the blank time period which is logically
ORed for both bridges. Here all transistors become switched off for the rest of the PW M cycle,
because the bridge with the failure is unknown.
The overcurrent flags can be cleared by disabling and re-enabling the chip either via the ENN pin or by
sending a telegram with both current control words set to “0000”. In high side overcurrent conditions
the user can determine which bridge sees the overcurrent, by selectively switching on only one of the
bridges with each polarity (therefore the other bridge should remain programmed to “0000”).
Over temperature protection and diagnosis
The circuit switches off all output power transistors during an over temperature condition. The over
temperature flag should be monitored to detect this condition. The circuit resumes operation after cool
down below the temperature threshold. However, operation near the over temperature threshold
should be avoided, if a high lifetime is desired.
Overvoltage protection and ENN pin behavior
During disable conditions the circuit switches off all output power transistors and goes into a low
current shutdown mode. All register contents is cleared to “0”, and all status flags are cleared. The
circuit in this condition can also stand a higher voltage, because the voltage then is not limited by the
maximum power MOSFET voltage. The enable pin ENN provides a fixed threshold of ½ VCC to allow a
simple overvoltage protection up to 40V using an external voltage divider (see schematic).
+VM
R1
for switch off at 26 - 29V:
at VCC=5V: R1=100K; R2=10K
at VCC=3.3V: R1=160K; R2=10K
ENN
R2
µC-Port (opt.)
low=Enable,
high=Disable
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
14
Chopper Principle
Chopper cycle / Using the mixed decay feature
RSENSE
SWO
SWC
SWO
RSENSE
On phase:
Current flows in target
direction
I
SWC
SWO
SWC
I
SWO
SWO
SWC
I
SWO
SWC
The TMC246 uses a quiet fixed frequency chopper. Both coils are chopped with a phase shift of 180
degrees. The mixed decay option is realized as a self stabilizing system (pat. fi.), by shortening the fast
decay phase, if the ON phase becomes longer. It is advised to enable the mixed decay for each phase
during the second half of each microstepping half-wave, when the current is meant to decrease. This
leads to less motor resonance, especially at medium velocities. With low velocities or during standstill
mixed decay should be switched off. In applications requiring high resolution, or using low inductivity
motors, the mixed decay mode can also be enabled continuously, to reduce the minimum motor
current which can be achieved. When mixed decay mode is continuously on or when using high
inductivity motors at low supply voltage, it is advised to raise the chopper frequency to minimum
36kHz, because the half chopper frequency could become audible under these conditions.
RSENSE
Fast decay phase:
Current flows back into
power supply
Slow decay phase:
Current re-circulation
target current phase A
actual current phase A
on
slow decay
on
fast decay
slow decay
oscillator clock
resp. external clock
mixed decay disabled
mixed decay enabled
When polarity is changed on one bridge, the PWM cycle on that bridge becomes restarted at once.
Fast decay switches off both upper transistors, while enabling the lower transistor opposite to the
selected polarity. Slow decay always enables both lower side transistors.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
15
Adapting the sine wave for smooth motor operation
After reaching the target current in each chopper cycle, both, the slow decay and the fast decay cycle
reduce the current by some amount. Especially the fast decay cycle has a larger impact. Thus, the
medium coil current always is a bit lower than the target current. This leads to a flat line in the current
shape flowing through the motor. It can be corrected, by applying an offset to the sine shape. In mixed
decay operation via SPI, an offset of 1 does the job for most motors.
Target current
I
Target current
I
Coil current
Coil current
t
Coil current does not have optimum shape
t
Target current corrected for optimum shape of coil current
Blank Time
The TMC246 uses a digital blanking pulse for the current chopper comparators. This prevents current
spikes, which can occur during switching action due to capacitive loading, from terminating the
chopper cycle. The lowest possible blanking time gives the best results for microstepping: A long blank
time leads to a long minimum turn-on time, thus giving an increased lower limit for the current. Please
remark, that the blank time should cover both, switch-off time of the lower side transistors and turn-on
time of the upper side transistors plus some time for the current to settle. Thus the complete switching
duration should never exceed 1.5µs.
The TMC246 allows adapting the blank time to the load conditions and to the selected slope in four
steps (the effective resulting blank times are about 200ns shorter in the non-A-type):
Blank time settings
BL2
BL1
Typical blank time
GND
GND
0.6 µs
GND
VCC
0.9 µs
VCC
GND
1.2 µs
VCC
VCC
1.5 µs
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
16
Classical non-SPI control mode (stand alone mode)
The driver can be controlled by analog current control signals and digital phase signals. To enable this
mode, tie pin SPE to GND. In this mode, the SPI interface is disabled and the SPI input pins have
alternate functions. The internal DACs are forced to “1111”.
Pin functions in stand alone mode
Pin
Stand alone
mode name
Function in stand alone mode
SPE
(GND)
Tie to GND to enable stand alone mode
ANN
MDAN
Enable mixed decay for bridge A (low = enable)
SCK
MDBN
Enable mixed decay for bridge B (low = enable)
SDI
PHA
Polarity bridge A (low = current flow from output OA1 to OA2)
CSN
PHB
Polarity bridge B (low = current flow from output OB1 to OB2)
SDO
ERR
Error output (high = overcurrent on any bridge, or overtemperature). In this
mode, the pin is never tristated.
ENN
ENN
Standby mode (high active), high causes a low power mode of the device.
Setting this pin high also resets all error conditions.
INA,
INB
INA,
INB
Current control for bridge A, resp. bridge B. Refer to AGND. The sense
resistor trip voltage is 0.34V when the input voltage is 2.0V. Maximum input
voltage is 3.0V.
Input signals for microstep control in stand alone mode
Attention: When transferring these waves to SPI operation, please remark, that the mixed decay bits
are inverted when compared to stand alone mode.
INA
INB
90°
180°
270°
360°
PHA
(SDI)
PHB
(CSN)
MDAN
(ANN)
MDBN
(SCK)
Use dotted line to improve performance
at medium velocities
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
17
Calculation of the external components
Sense Resistor
Choose an appropriate sense resistor (RS) to set the desired motor current. The maximum motor
current is reached, when the coil current setting is programmed to “1111”. This results in a current
sense trip voltage of 0.34V when the internal reference or a reference voltage of 2V is used.
When operating your motor in fullstep mode, the maximum motor current is as specified by the
manufacturer. When operating in sinestep mode, multiply this value by 1.41 for the maximum current
(Imax).
RS = VTRIP / Imax
In a typical application:
RS = 0.34V / Imax
RS:
VTRIP:
Imax:
Current sense resistor of bridge A, B
Programmed trip voltage of the current sense comparators
Desired maximum coil current
Examples for sense resistor settings
RS
0.47
0.43
0.39
0.33
0.27
0.22
Imax
723mA
790mA
870mA
1030mA
1259mA
1545mA
High side overcurrent detection resistor RSH
The TMC246 detects an overcurrent to ground, when the voltage between VS and VT exceeds 150mV.
The high side overcurrent detection resistor should be chosen in a way that 100mV voltage drop are
not exceeded between VS and VT, when both coils draw the maximum current. In a sinestep
application, this is when sine and cosine wave have their highest sum, i.e. at 45 degrees,
corresponding to 1.41 times the maximum current setting for one coil. In a fullstep application this is
the double coil current.
In a microstep application:
RSH = 0.1V / (1.41 Imax)
In a fullstep application:
RSH = 0.1V / (2 Imax)
RSH:
Imax:
High side overcurrent detection resistor
Maximum coil current
However, if the user desires to use higher resistance values, a voltage divider in the range of 10 to
100 can be used for VT. This might also be desired to limit the peak short to GND current, as
described in the following chapter.
Attention: A careful PCB layout is required for the sense resistor traces and for the RSH traces.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
18
Making the circuit short circuit proof
In practical applications, a short circuit does not describe a static condition, but can be of very different
nature. It typically involves inductive, resistive and capacitive components. Worst events are
unclamped switching events, because huge voltages can build up in inductive components and result
in a high energy spark going into the driver, which can destroy the power transistors. The same is true
when disconnecting a motor during operation: Never disconnect the motor during operation!
There is no absolute protection against random short circuit conditions, but pre-cautions can be taken
to improve robustness of the circuit:
In a short condition, the current can become very high before it is interrupted by the short detection,
due to the blanking during switching and internal delays. The high-side transistors allows up to 10A
flowing for the selected blank time. The lower the external inductivity, the faster the current climbs. If
inductive components are involved in the short, the same current will shoot through the low-side
resistor and cause a high negative voltage spike at the sense resistor. Both, the high current and the
voltage spikes are a danger for the driver.
Thus there are a two things to be done, if short circuits are expected:
1. Protect SRA/SRB inputs using a series resistance
2. Increase RSH to limit maximum transistor current: Use same value as for sense resistors
3. Use as short as possible blank time
The second measure effectively limits short circuit current, because the upper driver transistor with its
fixed ON gate voltage of 7V forms a constant current source together with its internal resistance and
RSH. A positive side effect is, that only one type of low ohmic resistor is required. The drawback is, that
power dissipation increases slightly. A high side short detection resistor of 0.33 Ohms limits maximum
high side transistor current to typically 4A. The schematic shows the modifications to be done.
However, the effectiveness of these measures should be tested in the given application.
VS
RDIV
RSH
100nF
VT
+VM
100R
GND
RSH=RSA=RSB
RDIV values for
Microstep:
Fullstep:
internal
reference
27R
18R
INA/INB
up to3V
18R
12R
CVM
SRA
100R
SRB
RSA
RSB
100R
GND
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
19
Oscillator Capacitor
The PWM oscillator frequency can be set by an external capacitor. The internal oscillator uses a 28k
resistor to charge / discharge the external capacitor to a trip voltage of 2/3 Vcc respectively 1/3 Vcc. It
can be overdriven using an external CMOS level square wave signal. Do not set the frequency higher
than 100kHz and do not leave the OSC terminal open! The two bridges are chopped with a phase shift
of 180 degrees at the positive and at the negative edge of the clock signal.
1
fOSC
40s COSC [nF]
fOSC:
COSC:
PWM oscillator frequency
Oscillator capacitor in nF
Table of oscillator frequencies
fOSC typ.
16.7kHz
20.8kHz
25.0kHz
30.5kHz
36.8kHz
44.6kHz
COSC
1.5nF
1.2nF
1.0nF
820pF
680pF
560pF
Please remark, that an unnecessary high frequency leads to high switching losses in the power
transistors and in the motor. For most applications a chopper frequency slightly above audible range is
sufficient. When audible noise occurs in an application, especially with mixed decay continuously
enabled, the chopper frequency should be two times the audible range. For most applications we
recommend a frequency of 36.8kHz.
Pullup resistors on unused inputs
The digital inputs all have integrated pull-up resistors, except for the ENN input, which is in fact an
analog input. Thus, there are no external pull-up resistors required for unused digital inputs which are
meant to be positive.
Power supply sequencing considerations
Upon power up, the driver initializes and switches off the bridge power transistors. However, in order
for the internal startup logic to work properly, the Vcc supply voltage has to be at least 1.0V,
respectively, the Vs supply voltage has to be at least 5.0V. When Vs goes up with Vcc at 0V, a medium
current temporary cross conduction of the power stage can result at supply voltages between 2.4V and
4.8V. While this does no harm to the driver, it may hinder the power supply from coming up properly,
depending on the power supply start up behavior.
In order to prevent this from occurring, either use a dual voltage power supply, or use a local regulator,
generating the 5V or 3.3V Vcc voltage.
Please pay attention to the local regulator start up voltage: Some newer switching regulators do not
start before the input voltage has reached 5V. Therefore it is recommended to use a standard linear
regulator like 7805 series or LM317 or a low drop regulator or a switching regulator like the LM2595,
starting at relatively low input voltages.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
20
Slope Control Resistor
The output-voltage slope of the full bridge outputs can be controlled to reduce noise on the power
supply and on the motor lines and thus electromagnetic emission of the circuit. It is controlled by an
external resistor at the SLP pin.
Operational range:
0k RSLP 100k
The SLP-pin can directly be connected to AGND for the fastest output-voltage slope (respectively
maximum output current). In most applications a minimum external resistance of 10 K is
recommended to avoid unnecessary high switching spikes.
Only for non-A-types the slope on the lower transistors is fixed (corresponding to a 5K to 10K slope
control resistor). For applications where electromagnetic emission is very critical, it might be necessary
to add additional LC (or capacitor only) filtering on the motor connections.
For these applications emission is lower, if only slow decay operation is used.
Please remark, that there is a tradeoff between reduced electromagnetic emissions (slow slope) and
high efficiency because of low dynamic losses (fast slope).
The following table and graph depict typical behavior measured from 15% of output voltage to 85% of
output voltage. However, the actual values measured in an application depend on multiple parameters
and may stray in a user application.
Example for slope settings
tSLP [ns] @ 10V
tSLP [ns] @ 24V
tSLP typ.
30ns
60ns
110ns
245ns
460ns
RSLP
2.2K
10K
22K
51K
100K
500
200
100
50
20
10
0
1
2
5
10
RSLP in KOhm
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
20
50
100
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
21
Absolute Maximum Ratings
The maximum ratings may not be exceeded under any circumstances.
Symbol Parameter
Min
Max
Unit
VS
Supply voltage (A-type/B-type)
-0.3
36
V
VS
Supply voltage (non-A/B-type)
-0.3
30
V
VMD
Supply and bridge voltage max. 20000s
(non-A-type: device disabled)
40
V
VTR
Power transistor voltage VOA-VBRA, VOBVBRB, VSA-VOA, VSB-VOB (A/B-type)
40
V
VTR
Power transistor voltage VOA-VBRA, VOBVBRB, VSA-VOA, VSB-VOB (non-A/B-type)
30
V
VCC
Logic supply voltage
6.0
V
IOP
Output peak current (10µs pulse)
+/-7
A
IOC
Output current
(continuous, per bridge)
TA 85°C
1500
mA
TA 105°C
1000
TA 125°C
800
-0.5
VI
Logic input voltage
-0.3
VCC+0.3V
V
VIA
Analog input voltage
-0.3
VCC+0.3V
V
IIO
Maximum current to / from digital pins
+/-10
mA
VS-1V
VS+0.3V
V
and analog inputs
VVT
Short-to-ground detector input voltage
TJ
Junction temperature
-40
150 (1)
°C
TSTG
Storage temperature
-55
150
°C
(1) Internally limited
Electrical Characteristics
Operational Range
Symbol Parameter
Min
Max
Unit
TAI
Ambient temperature industrial (1)
-25
125
°C
TAA
Ambient temperature automotive
-40
125
°C
TJ
Junction temperature
-40
140
°C
VS
Bridge supply voltage (A-type/B-type)
7
34
V
VS
Bridge supply voltage (non-A/B-type)
7
28.5
V
VCC
Logic supply voltage
3.0
5.5
V
fCLK
Chopper clock frequency
50
kHz
RSLP
Slope control resistor
110
K
0
(1) The circuit can be operated up to 140°C, but output power derates.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
22
DC Characteristics
DC characteristics contain the spread of values guaranteed within the specified supply voltage and
temperature range unless otherwise specified. Typical characteristics represent the average value of
all parts.
Logic supply voltage: VCC = 3.0 V ... 5.5 V,
Junction temperature: TJ = -40°C … 150°C,
Bridge supply voltage: VS = 7 V … 34 V
(unless otherwise specified)
Symbol
ROUT,Sink
Parameter
Conditions
RDSON of sink-FET (A-type)
ROUT,Source RDSON of source-FET (A-type)
ROUT,Sink
RDSON of sink-FET max. (A-type)
ROUT,Source RDSON of source-FET max.
(A-Type)
ROUT,Sink
RDSON of sink-FET (B-type)
ROUT,Source RDSON of source-FET (B-type)
ROUT,Sink
RDSON of sink-FET max. (B-type)
ROUT,Source RDSON of source-FET max.
(B-Type)
Min
Typ
Max
Unit
TJ = 25°C
VS 8V
0.12
0.19
0.22
0.36
TJ =150°C
VS 8V
0.20
0.26
0.37
0.47
TJ = 25°C
VS 8V
0.10
0.14
0.17
0.23
TJ =150°C
VS 8V
0.16
0.23
0.28
0.38
VDIO
Diode forward voltages of Oxx
MOSFET diodes (A-type)
TJ = 25°C
IOXX = 1.05A
0.84
1.21
V
VDIO
Diode forward voltages of Oxx
MOSFET diodes (B-type)
TJ = 25°C
IOXX = 1.05A
0.77
1.2
V
VCCUV
VCC undervoltage
2.5
2.7
2.9
V
VCCOK
VCC voltage o.k.
2.7
2.9
3.0
V
0.85
1.35
mA
0.45
0.75
mA
37
70
µA
ICC
VCC supply current
fosc = 25 kHz
ICCSTB
VCC supply current standby
ICCSD
VCC supply current shutdown
VSUV
VS undervoltage
5.5
5.9
6.2
V
VCCOK
VS voltage o.k.
6.1
6.4
6.7
V
ISSM
ENN = 1
VS supply current with fastest
slope setting (static state)
VS = 14V,
ISSD
VS supply current shutdown or
standby
VS = 14V
VIH
High input voltage
(SDI, SCK, CSN, BL1, BL2, SPE, ANN)
VIL
6
mA
RSLP = 0K
50
µA
2.2
VCC +
0.3 V
V
Low input voltage
(SDI, SCK, CSN, BL1, BL2, SPE, ANN)
-0.3
0.7
V
VIHYS
Input voltage hysteresis
(SDI, SCK, CSN, BL1, BL2, SPE, ANN)
100
300
500
mV
VOH
High output voltage
(output SDO)
-IOH = 1mA
VCC –
0.6
VCC –
0.2
VCC
V
VOL
Low output voltage
(output SDO)
IOL = 1mA
0
0.1
0.4
V
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
28
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
-IISL
Low input current
(SDI, SCK, CSN, BL1, BL2, SPE, ANN)
VI = 0
VCC = 3.3V
VCC = 5.0V
23
2
70
µA
µA
µA
10
25
VENNH
High input voltage threshold
(input ENN)
VEHYS
Input voltage hysteresis
(input ENN)
VOSCH
High input voltage threshold
(input OSC)
tbd
2/3 VCC
tbd
V
VOSCL
Low input voltage threshold
(input OSC)
tbd
1/3 VCC
tbd
V
VVTD
VT threshold voltage
(referenced to VS)
-130
-155
-180
mV
VTRIP
SRA / SRB voltage at
DAC=”1111”
315
350
385
mV
VSRS
SRA / SRB overcurrent detection
threshold
570
615
660
mV
SRA / SRB comparator offset
voltage
-10
0
10
mV
175
264
300
k
VSROFFS
RINAB
INA / INB input resistance
1/2 VCC
0.1
VENNH
internal ref. or
2V at INA / INB
Vin 3 V
AC Characteristics
AC characteristics contain the spread of values guaranteed within the specified supply voltage and
temperature range unless otherwise specified. Typical characteristics represent the average value of
all parts.
Logic supply voltage: VCC = 5.0V,
Bridge supply voltage: VS = 14.0V,
Ambient temperature: TA = 27°C
Symbol Parameter
fOSC
Oscillator frequency
using internal oscillator
tRS, tFS
tRS, tFS
tRS, tFS
TBL
TONMIN
Conditions
Min
Typ
Max
Unit
COSC = 1nF
1%
20
25
31
kHz
Rise and fall time of outputs Oxx
with RSLP=0
Vo 15% to 85%
Rise and fall time of outputs Oxx
with RSLP = 25K
Vo 15% to 85%
Rise and fall time of outputs Oxx
with RSLP = 50K
Vo 15% to 85%
Effective Blank time
BL1, BL2 = VCC
Minimum PWM on-time
BL1, BL2 =
GND
25
ns
125
ns
250
ns
IOXX = 800mA
IOXX = 800mA
IOXX = 800mA
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
1.35
1.5
0.7
1.65
µs
µs
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
24
Thermal Protection
Symbol
TJOT
TJOTHYS
TJWT
TJWTHYS
Parameter
Conditions
Thermal shutdown
Min
Typ
Max
Unit
145
155
165
°C
TJOT hysteresis
15
Prewarning temperature
135
TJWT hysteresis
145
°C
155
15
°C
°C
Thermal Characteristics
Symbol
Parameter
Conditions
Typ
Unit
RTHA12
Thermal resistance bridge transistor junction to
ambient, one bridge chopping, fixed polarity
soldered to 2 layer
PCB
88
°K/W
RTHA22
Thermal resistance bridge transistor junction to
ambient, two bridges chopping, fixed polarity
soldered to 2 layer
PCB
68
°K/W
RTHA14
Thermal resistance bridge transistor junction to
ambient, one bridge chopping, fixed polarity
soldered to 4 layer
PCB (pessimistic)
84
°K/W
RTHA24
Thermal resistance bridge transistor junction to
ambient, two bridges chopping, fixed polarity
soldered to 4 layer
PCB (pessimistic)
51
°K/W
Typical Power Dissipation at high load / high temperature
Coil:
Chopping with:
LW = 10mH, RW = 5.0
tDUTY = 33% ON, only slow decay
Current
Current
Ambient
both brid- one bridge temperature
ges on
on
TA
Motor supply Slope
voltage
tSLP
VM
Chopper
frequency
fCHOP
Typ total power
dissipation
PD
560 mA
560 mA
16 V
16 V
14 V
14 V
28 V
28 V
25 KHz
25 KHz
20 KHz
20 KHz
25 KHz
25 KHz
490 mW
450 mW
350 mW
340 mW
1000 mW
1100 mW
1000 mA
-
800 mA
800 mA
1500 mA
105 °C
105 °C
125 °C
125 °C
70 °C
70 °C
400 ns
400 ns
60ns
60ns
60ns
60ns
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
25
SPI Interface Timing
tES
ENN
CSN
t1
tCL
tCH
t1
t1
SCK
tDU
SDI
bit11
tDH
bit10
bit0
tD
SDO
tZC
bit11
bit10
bit0
Propagation Times
(3.0 V VCC 5.5 V, -40°C Tj 150°C; VIH = 2.8V, VIL = 0.5V; tr, tf = 10ns; CL = 50pF,
unless otherwise specified)
Symbol
fSCK
Parameter
SCK frequency
Conditions
Min
ENN = 0
DC
Typ
Max
Unit
4
MHz
t1
SCK stable before and after CSN
change
50
ns
tCH
Width of SCK high pulse
100
ns
tCL
Width of SCK low pulse
100
ns
tDU
SDI setup time
40
ns
tDH
SDI hold time
50
ns
tD
SDO delay time
tZC
CSN high to SDO high impedance
tES
ENN to SCK setup time
tPD
CSN high to OA / OB output polarity
change delay
tLD
Load indicator valid after OA / OB
output polarity change
CL = 50pF
*)
**)
40
100
ns
50
ns
30
µs
3
tOSC + 4
µs
5
7
µs
*) SDO is tristated whenever ENN is inactive (high) or CSN is inactive (high).
**) Whenever the PHA / PHB polarity is changed, the chopper is restarted for that phase. However, the chopper does not
switch on, when the SRA resp. SRB comparator threshold is exceeded upon the start of a chopper period.
Using the SPI interface
The SPI interface allows either cascading of multiple devices, giving a longer shift register, or working
with a separate chip select signal for each device, paralleling all other lines. Even when there is only
one device attached to a CPU, the CPU can communicate with it using a 16 bit transmission. In this
case, the upper 4 bits are dummy bits.
SPI Filter
To prevent spikes from changing the SPI settings, SPI data words are only accepted, if their length is
at least 12 bit.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
26
ESD Protection
Please be aware, that the TMC246 is an ESD sensitive device due to integrated high performance
MOS transistors.
ESD sensitive device
If the ICs are manually handled before / during soldering, special precautions have to be taken to avoid
ESD voltages above 100V HBM (Human body model). For automated SMD equipment the internal
device protection is specified with 1000V CDM (charged device model), tbf.
When soldered to the application board, all inputs and outputs withstand at least 1000V HBM.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
27
Application Note: Extending the Microstep Resolution
For some applications it might be desired to have a higher microstep resolution, while keeping the
advantages of control via the serial interface. The following schematic shows a solution, which adds
two LSBs by selectively pulling up the SRA / SRB pin by a small voltage difference. Please remark, that
the lower two bits are inverted in the depicted circuit. A full scale sense voltage of 340mV is assumed.
The circuit still takes advantage of completely switching off of the coils when the internal DAC bits are
set to “0000”. This results in the following comparator trip voltages:
Current setting
Trip voltage
(MSB first)
0000xx
0V
000111
5.8 mV
000110
11.5 mV
000101
17.3 mV
000100
23 mV
...
111101
334.2 mV
111100
340 mV
SPI bit
DAC bit
SPI bit
DAC bit
15
/B1
7
A2
14
/B0
6
PHA
13
/A1
5
MDB
12
/A0
4
B5
11
MDA
3
B4
10
A5
2
B3
9
A4
1
B2
SCK
SCK
SDI
SDI
TMC236 /
TMC239
SDO
SRA
110R
4.7nF
opt.
CSN
/CS
47K
47K
RS
47K
+VCC
100K
/OE
C2
/MR
C1
DS1D
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
/DACA.0
/DACA.1
/DACB.0
/DACB.1
Free for
second
TMC239
Q7'
74HC595
Vcc = 5V
C
SDO
Q
D
1/2 74HC74
Note: Use a 74HC4094
instead of the HC595 to get
rid of the HC74 and inverter
Please see the FAQ document for more application information.
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
8
A3
0
PHB
TMC246 / TMC246A / TMC246B DATA SHEET (V2.10 / 2016-Jun-06)
28
Documentation Revision
Version
Author
Description
BD= Bernhard Dwersteg
V1.00
V2.04
V2.05
V2.06
V2.10
i
BD
BD
BD
BD
BD
First version, Sept. 2003
Added power supply sequencing considerations
Adapted style, added info on chopper cycle
Corrected ENN timing in SPI section
Added IC revision TMC246B with improved MOSFETs – see chapter
“Electrical Characteristics” for any differences.
SPI is a trademark of Motorola
Copyright © 2005, TRINAMIC Motion Control GmbH & Co KG
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