POWER DRIVER FOR DC MOTORS
INTEGRATED CIRCUITS
TMC7300 Datasheet
Low Voltage Driver for One or Two DC Motors up to 2A (2.4A) peak – UART based Control for Torque
and Velocity. 4 Half Bridge Peripheral Driver Option.
APPLICATIONS
IOT & Handheld devices
Battery operated motors
4-Channel Relay- and LED driving
Printers, POS
Toys
Office and home automation
CCTV, Security
HVAC
Mobile medical devices
FEATURES
AND
BENEFITS
Voltage Range 2V (1.8V) … 11V DC
Battery Operation min. 2 AA / NiMh cells, or 1-2 Li-Ion cells
1 / 2 DC motors up to 2A / 2.4A with velocity & torque control
Direct Bridge control for solenoids, relays, lamps, motors…
Single Wire UART for two-motor torque and velocity control
Standby 10µF near pin with
shortest possible loop to GND pad.
DC motor 1 output 2
Sense resistor connection for coil A or DC motor 1. Place sense
resistor to GND near pin.
Connect the exposed die pad to a GND plane. Provide as many as
possible vias for heat transfer to GND plane.
BRA
OA1
VS
OB1
BRB
2.3 Package Outline / Halfbridge mode
18
17
16
4
5
7
8
9
13
OB2
GND
1.8VOUT
DIAG
VIO/NSTDBY
10
B2
EN
ENUART
MODE
PWM
6
12
3
TMC7300
(4 Halfbridge)
© B. Dwersteg,
TRINAMIC
PAD
11
2
14
1
OA2
VCP
A1
A2
B1
19
15
20
Figure 2.2 TMC7300 Pinning Top View Stepper Driver – QFN20, 3x3mm², 0.4mm pitch
2.4 Signal Descriptions / Halfbridge mode
Pin
OA2
Number
1
VCP
2
A1
A2
B1
B2
3
4
5
6
DI
DI
DI
DI
EN
7
DI
ENUART
MODE
8
9
DI
DI
PWM
10
DI
VIO/NSTDBY
11
DIAG
12
1.8VOUT
13
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Type
DO
Function
Bridge A output 2
Charge pump voltage. Optionally tie to VS using 1nF to 100nF
capacitor. May be left unconnected if maximum 2 pins change at a
time.
Bridge A output 1 polarity
Bridge A output 2 polarity
Bridge B output 1 polarity
Bridge B output 2 polarity
Enable input. The power stage becomes switched off (all motor
outputs floating) when this pin becomes driven to a low level.
Also used to release driver after fault shutdown.
tie to GND
tie to VIO
Common PWM for high-side drivers. Tie high to enable high-side
drivers as controlled by A and B inputs. Influences high-side driver,
only.
1.8V to 5V IO supply voltage for all digital pins. IC goes to standby
mode and resets, when this pin is pulled to GND.
Diagnostic output. High level upon driver error. Reset by EN=low.
Output of internal 1.8V regulator. Attach 100nF ceramic capacitor to
GND near to pin for best performance. Provide the shortest
possible loop to the GND pad.
TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
Pin
GND
OB2
Number
14
15
BRB
16
OB1
17
VS
18
OA1
19
BRA
20
Exposed
die pad
-
www.trinamic.com
Type
9
Function
GND. Connect to GND plane near pin.
Bridge B output 2
Foot point of bridge B. Connect to GND directly, or via a sense
resistor, if external current measurement is desired.
Bridge B output 1
Bridge supply voltage. Provide filtering capacity >10µF near pin
with shortest possible loop to GND pad.
Bridge A output 1
Foot point of bridge A. Connect to GND directly, or via a sense
resistor.
Connect the exposed die pad to a GND plane. Provide as many as
possible vias for heat transfer to GND plane.
TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
3
10
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. The
TMC7300 is configured for different application modes by two pins, as well as by settings available via
the UART interface.
3.1 DC Motor Operation
Optional external
capacitor
A2
VCP
100n
1.8VOUT
Place near IC with
short path to die pad
A1
+VM
VS
TMC7300
1.8V Voltage
regulator
1n-100n
10V
STANDBY
100n
Internal charge
pump
10µ
OA1
Full Bridge A
Or low ESR 100µF
electrolytic / depending
on supply resistance
and motor current
M
OA2
AD0
UART Address
Configuration
(GND or VIO)
AD1
Configuration
Interface
ENUART
MODE
UART interface
Driver error
1.8V to 5V
I/O voltage
/ standby
B. Dwersteg, ©
TRINAMIC 2016
UART
UART interface
+ Register Block
DIAG
Programmable
Diagnostic
Output
VIO/
NSTDBY
100n
Standby
detector
BRA
RSA
DC motor PWM
BRA
Current
regulator
Connect directly
to GND plane
BRB
Use low inductivity SMD
type for R SA and RSB
OB1
Full Bridge B
M
OB2
STANDBY
BRB
500k
RSB
CLK oscillator
driver enable
(disable prior to
configuration!)
GND
DIE PAD
EN
Connect directly
to GND plane
Figure 3.1 Operation of two DC-Motors for 1.8V to 11V supply
The standard application circuit uses a minimum set of additional components to operate one or two
DC motors. Each one sense resistor sets the motor current limit. See chapter 7 to choose the right
sense resistor value. Take care to keep power supply ripple due to chopper operation at a few 100mV,
max., especially when low voltage operation is desired. Use ceramic, or low ESR capacitors for
filtering the power supply. The capacitors need to cope with the current ripple caused by chopper
operation. A minimum capacity of 100µF electrolytic, or a 10µF ceramic capacitor near the driver is
recommended to keep ripple low. Actual demand will depend on the internal power supply resistance
and the desired motor current. VCC_IO can be supplied from a separate supply, e.g. a 3.3V regulator,
or be driven by a microcontroller port pin. AD0 and AD1 set the UART address. Ensure, that the EN pin
is driven by the microcontroller in order to disable the motor prior to initialization! Apply a pulldown
resistor for EN to keep it low during power-up.
Basic layout and component 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 1.8VOUT filtering capacitor
directly to 1.8VOUT and the GND pin. See layout hints for more details. Low ESR electrolytic capacitors
are recommended for VS filtering unless supply resistance is very low.
Attention
Power up with EN-pin low. Set GCONF.pwm_direct prior to enabling the driver via EN-pin. Otherwise
the motor will run directly after power-up.
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TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
11
A2
VCP
100n
1.8VOUT
Place near IC with
short path to die pad
1.8V Voltage
regulator
+VM
VS
TMC7300
A1
1n-100n
10V
STANDBY
100n
Internal charge
pump
10µ
OA1
Full Bridge A
Or low ESR 100µF
electrolytic / depending
on supply resistance
and motor current
M
OA2
AD0
UART Address
Configuration
(GND or VIO)
AD1
Configuration
Interface
ENUART
MODE
UART interface
Driver error
1.8V to 5V
I/O voltage
/ standby
B. Dwersteg, ©
TRINAMIC 2016
UART
UART interface
+ Register Block
DIAG
Programmable
Diagnostic
Output
VIO/
NSTDBY
100n
Standby
detector
BRA
DC motor PWM
BRA
Current
regulator
BRB
OB1
Full Bridge B
OB2
STANDBY
BRB
500k
RS
Use low inductivity SMD
type for R S
CLK oscillator
driver enable
(disable prior to
configuration!)
GND
DIE PAD
EN
Connect directly
to GND plane
Figure 3.2 Operation of a single DC-Motor (double current)
A single DC-motor can be operated at double current (up to 2.4A), by paralleling both power-stages.
Before operating the motor, the IC has to be switched to parallel mode, because default setting will
cause a short circuit between the bridges and a high current flow, which will trigger overcurrent
protection. Therefore ensure, that the EN pin is driven by the microcontroller in order to disable the
motor prior to initialization. Apply a pulldown resistor for EN additionally to ensure power-up with a
low level.
Attention
For parallel operation, power up with EN-pin low. Set GCONF.par_mode in order to force identical
drive signals prior to enabling the driver via EN-pin. In this mode, a capacitor is required on pin VCP.
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TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
12
3.2 Halfbridge Driver Mode
Halfbridge driver mode offers four separate half-bridges to individually drive and control resistive and
inductive loads, like LEDs, solenoids, etc. In case a current measurement is desired, each two
halfbridges allow adding a foot point shunt resistor. Keep voltage drop in this resistor to maximum
400mV for normal operation. A common high-side PWM input allows switching off all high-side
drivers at the same time. It does not influence drivers, where the low-side is on. If more than two
drivers are switched at the same time, a capacitor on pin VCP is recommended. The diagnostic output
signals any overcurrent or overtemperature condition. The driver automatically restarts after power-up,
or after cycling VIO_NSTDBY pin.
VCP
100n
Optional external
capacitor
1.8VOUT
Place near IC with
short path to die pad
1n-100n
10V
+VM
VS
TMC7300
1.8V Voltage
regulator
100n
Internal charge
pump
STANDBY
Common PWM
for High-Side
OA2
PWM
A1
Or low ESR 100µF
electrolytic / depending
on supply resistance
and motor current
Inductive or resistive
loads between each
two pins, to GND or to
VM
OA1
Full Bridge A
10µ
BRA
A2
Individual output
polarity control
B1
BBM logic
B2
B. Dwersteg, ©
TRINAMIC 2016
DIAG
Driver error
100n
Inductive or resistive
loads between each
two pins, to GND or to
VM
OB1
Diagnostic
Output
VIO/
NSTDBY
1.8V to 5V
I/O voltage
/ standby
Connect directly
to GND plane or
via sense resistor
Full Bridge B
Standby
detector
OB2
STANDBY
BRB
500k
+VIO
GND
+VIO
DIE PAD
EN
MODE
ENUART
Connect directly
to GND plane or
via sense resistor
opt. driver enable
Figure 3.3 Halfbridge Driver Mode
PWM
H
H
H
x
x
L
L
L
EN
H
H
H
H
L
H
L
H
Input 1
H
L
H
L
xx
H
H
L
Input 2
L
H
H
L
xx
H
L
H
Output 1
H
L
H
L
high-Z
high-Z
high-Z
L
Table 3.1 Truth table for DC motor in half bridge mode
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Output 2
L
H
H
L
high-Z
high-Z
L
high-Z
Mode (with motor)
CW
CCW
Brake (high side)
Brake (low side)
coast
coast
CCW brake / CW coast
CW brake / CCW coast
TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
13
3.3 Highly Efficient Driver
The TMC7300 integrates a highly efficient power stage, offering low RDSon even at low supply
voltages, due to its internal charge pump. This enables high motor current drive capability and low
power dissipation for battery powered applications.
RDSon vs. VS
400,00
350,00
300,00
250,00
200,00
150,00
100,00
50,00
0,00
1,5
2,0
2,5
RDSon (LS) [mOhm]
3,0
3,5
4,0
RDSon(HS) [mOhm]
Figure 3.4 RDSon Variation over Supply Voltage
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 tiny QFN 3mm x 3mm package at or above 0.8A mean motor current for increased
periods of time. For currents above 0.8A, a 4-layer PCB layout with 5 via contact of the die attach pad
to the GND plane is required. Keep in mind that resistive power dissipation raises 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 0.8A mean
current or more.
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TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
14
3.4 Low Power Standby
Battery powered applications, as well as mains powered applications conforming to EU energy saving
regulations, often require a standby mode, where the power-supply remains on. Current consumption
in this mode must be minimized. Control near zero power TMC7300 standby operation by switching
off the I/O supply voltage on VIO_NSTDBY pin. At the same time make sure, that no digital input pin
is at a high level. An input level above VIO_NSTDBY would hinder pulling down VIO_NSTDBY, due to
the ESD protection diodes in each digital I/O pin. These diodes clamp each input to a level between
GND and the IO supply voltage VIO_NSTDBY. Therefore, stop the motor first, and allow sufficient time
for the motor to come to a standstill, pull the enable input EN low, and also all other input pins, to
switch off the motor completely before switching off VIO voltage. All driver registers are reset to their
power-up defaults after leaving standby mode. See Figure 3.5.
Operation
Actual Power Draw
Low current standby
5mA
3mA
-100% to +100%)
PWM_B, signed: Bridge B PWM duty cycle
(-255 to +255 => -100% to +100%)
TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
23
5.3 Chopper Control Registers
CHOPPER CONTROL REGISTER SET (0X6C…0X7F)
R/W
Addr
n
Register
RW
0x6C
32
CHOPCONF
R
0x6F
32
DRV_
STATUS
RW
0x70
22
PWMCONF
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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!
Range [Unit]
Reset default=
0x13008001
Reset default=
0xC40D1024
TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
5.3.1
24
CHOPCONF – Chopper Configuration
0X6C: CHOPCONF – CHOPPER CONFIGURATION
Bit
31
Name
diss2vs
-
Function
Low side short
protection disable
short to GND
protection disable
reserved
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
set to 0 or leave unmodified
30
diss2g
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
-
reserved
set to 0 or leave unmodified
tbl1
tbl0
TBL
blank time select
-
reserved
%00 … %11:
Set current comparator blank time to 16, 24, 32 or 40
clocks
Hint: %00 or %01 is recommended for most applications
(Default: %01)
set to 0
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
enabledrv
driver enable
1: Enable driver (Default: 1, enable)
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TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
5.3.2
25
PWMCONF – Voltage PWM Mode StealthChop
0X70: PWMCONF – VOLTAGE MODE PWM STEALTHCHOP
Bit
31
30
29
28
27
26
25
24
23
22
21
20
Name
-
Function
reserved
Comment
set to 0 or leave unmodified
freewheel1
freewheel0
reserved
reserved
Allows different
standstill modes
19
18
17
16
pwm_freq1
pwm_freq0
reserved
reserved
PWM frequency
selection
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
-
reserved
set to 0
set to 0
Stand still option when motor current setting is zero
(I_HOLD=0).
%00: Normal operation (always selected with
motorrun=1)
%01: Freewheeling
%10: Coil shorted using LS drivers (passive braking)
%11: Coil shorted using HS drivers (passive braking)
set to 0 or leave unmodified
set to 0 or leave unmodified
%00: fPWM=2/1024 fCLK
%01: fPWM=2/683 fCLK
%10: fPWM=2/512 fCLK
%11: fPWM=2/410 fCLK
set to 0 or leave unmodified
-
reserved
set to 0 or leave unmodified
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TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
5.3.3
26
DRV_STATUS – Driver Status Flags
0X6F: DRV_STATUS – DRIVER STATUS FLAGS AND CURRENT LEVEL READ BACK
Bit
31..
10
9
8
7
6
Name
-
Function
0
Comment
Ignore these bits
t150
t120
lib
lia
150°C comparator
120°C comparator
load indicator phase B
load indicator phase A
5
s2vsb
4
s2vsa
3
s2gb
2
s2ga
1
ot
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, driver is off
1: Temperature prewarning threshold is exceeded
1: Current for motor cannot be reached.
0: Respective motor goes into current / torque limit
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 bridge A or B.
The driver becomes disabled. The flags stay active, until
the driver is disabled by software (enabledrv=0) or by
the ENN input.
1: Short to GND detected on bridge A or B. The driver
becomes disabled. The flags stay active, until the driver
is disabled by software (enabledrv=0) or by the ENN
input.
1: The 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 overtemperature pre-warning threshold is
exceeded.
The overtemperature pre-warning flag is common for
both bridges.
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overtemperature prewarning flag
TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
6
27
Chopper Options
UART
In order to match the motor voltage or current to a certain level, the effective PWM voltage becomes
scaled depending on the settings IRUN and PWM_A respectively PWM_B. Current limit takes over, in
case the motor current exceeds the limit as programmed by IRUN. This way, torque is limited as
desired, as well as current draw from the battery. Reaching the current limit can be used as
informative event: check lia resp. lib flags.
The Chopper PWM frequency can be chosen in four steps in order to adapt the chopper frequency to
the motor inductance. It balances low current ripple vs. increased dynamic power dissipation at
higher frequency.
CHOICE OF PWM FREQUENCY
Clock frequency
fCLK
PWM_FREQ=%00
fPWM=2/1024 fCLK
12MHz (typ. value)
23.4kHz
PWM_FREQ=%01
fPWM=2/683 fCLK
(default)
35.1kHz
PWM_FREQ=%10
fPWM=2/512 fCLK
PWM_FREQ=%11
fPWM=2/410 fCLK
46.9kHz
58.5kHz
Table 6.1 Choice of PWM frequency – green / light green: recommended
6.1 Load Indicator Flags
lia and lib indicate, if the original duty cycle is driven, or if current regulation limits the PWM duty
cycle. When read back as active, the original duty cycle is driven. A cleared flag results from current
limiting, e.g. when the motor is blocked, highly loaded, or still accelerating.
6.2 Freewheeling and Passive Braking
The chopper unit provides different options for motor standstill. These options can be enabled by
setting CURRENT_LIMIT.motorrun to zero, and choosing the desired option using via FREEWHEEL
setting. The PWM and current regulator become disabled in freewheeling and coil short modes. This
way, either freewheeling, or 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.
PARAMETERS RELATED TO CHOPPER
Parameter
PWM_FREQ
Description
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.
FREEWHEEL
Stand still option for both motors, when motorrun
flag is cleared (motorrun=0). The freewheeling
option makes the motor easy movable, while coil
short options realize a passive braking.
enabledrv
General enable for the motor driver
TBL
Comparator blank time. This time needs to safely
cover the switching event and the duration of the
ringing on the sense resistor. Choose a setting of
1 or 2 for typical applications. For higher
capacitive loads, 3 may be required.
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Setting
0
1
2
3
0
1
2
3
0
1
0
1
2
3
Comment
fPWM=2/1024 fCLK
fPWM=2/683 fCLK
fPWM=2/512 fCLK
fPWM=2/410 fCLK
Normal operation
Freewheeling
Coil short via LS drivers
Coil short cia HS drivers
Driver off, all outputs hi-Z
Driver enabled
16 tCLK
24 tCLK
32 tCLK
40 tCLK
TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
7
28
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. Additional 15mΩ PCB resistance are
included in the calculation.
CHOICE OF RSENSE AND RESULTING MAX. MOTOR CURRENT
RSENSE [Ω]
1.50
1.20
1.00
0.82
0.75
0.68
0.50
470m
390m
330m
270m
220m
180m
150m
120m
100m
82m
current limit [A]
IRUN=31
0.21
0.26
0.31
0.38
0.41
0.45
0.60
0.63
0.75
0.87
1.03
1.23
1.44
1.67
1.97
2.24 (single motor, parallel operation)
2.56 (single motor, parallel operation)
*) At high currents, duty cycle restriction for motion might apply, due to heat up of IC and board.
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 lowinductance, 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 14.
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 of the chopper. A 0.25W type is sufficient for most applications up to 800mA RMS.
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.
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TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
29
7.1 Motor Torque Limit
Select the sense resistors to deliver enough current for the motor at full current scale. This is the
default current scaling (IRUN = 31).
IRUN allows for scaling of the limit from 1/32 to 32/32:
MOTOR CURRENT CALCULATION WITH UART CONTROL OPTION:
𝐼𝑀𝐴𝑋 =
𝐼𝑅𝑈𝑁 + 1
𝑉𝐹𝑆
∗
32
𝑅𝑆𝐸𝑁𝑆𝐸 + 30𝑚Ω
VFS is the full-scale voltage (please refer to electrical characteristics, VSRT). Typical value is 325mV.
PARAMETERS FOR MOTOR CURRENT CONTROL
Parameter
IRUN
Description
Current limit scale when motor is running.
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Setting
0 … 31
Comment
scaling factor
1/32, 2/32, … 32/32
TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
8
30
Driver Diagnostic Flags
The TMC7300 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 current limit condition
allows testing if a motor coil connection is interrupted. See the DRV_STATUS table for details.
8.1 Temperature Measurement
The driver integrates a two-level temperature sensor (pre-warning and thermal shutdown) for
diagnostics and for protection of the IC against excess heat. Heat is mainly generated by the motor
driver stages. 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
Temperature
Level
150°C
120°C
Comment
This value is relatively safe 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.
Temperature level for pre-warning. In most applications, reaching this level is a
sign for abnormal heat accumulation. The overtemperature pre-warning threshold
of 120°C gives lots of headroom to react to high driver temperature, e.g. by
reducing motor current, or increasing waiting-time in between of two motions.
Attention
Overtemperature protection cannot in all cases avoid thermal destruction of the IC. In case the rated
output current is exceed, 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.
8.2 Short Protection
The TMC7300 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.
Once a short condition is safely detected, both driver bridges become switched off, and the s2ga or
s2gb flag, respectively s2vsa or s2vsb becomes set. In order to restart the motor, disable and reenable 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.
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TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
31
8.3 Diagnostic Output
drv_err
The diagnostic output DIAG provides error status information, especially when using the driver in
stand-alone mode. An active DIAG output shows that the driver cannot work normally. Figure 8.1
shows the signals controlling the output.
DIAG
Q S
R
Short circuit (s2vs, s2g) over temperature (ot)
Power stage disable (e.g. pin EN, STANDBY)
Power-on reset
Overtemperature (ot)
Figure 8.1 DIAG output
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TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
9
Quick Configuration Guide
32
UART
This guide is meant as a practical tool to come to a first configuration. Do a minimum set of
measurements and decisions for tuning the driver to fit the application.
PWM setup
Check hardware
setup and motor
max. current
Start with motor
disabled upon power-up
(EN=low)
Configure GCONF to
operate one or two
motors:
GCONF.PWM_direct=1
Single motor in
parallel config?
Y
For parallel operation
with a single motor, set
GCONF.par_mode = 1
Y
Set
PWM_CONF.freewheel
to %10 for braking when
motorrun=0
N
Set I_RUN as desired for
motor torque limit from
0 up to 31.
Set motorrun=1
Set initial PWM duty
cycle in PWM_A and
PWM_B and enable
motor using EN pin.
Passive braking
desired?
N
Operate motor using
PWM_A, PWM_B,
I_RUN, and motorrun
Figure 9.1 Configuration and Motor operation
Hint
Use the evaluation board to explore settings and to generate the required configuration datagrams.
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TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
33
10 External Reset
The chip is loaded with default values during power on via its internal power-on reset. In order to
reset the chip to power on defaults, any of the supply voltages monitored by internal reset circuitry
(VS or VCC_IO) must be cycled. It is easiest and safest to cycle VCC_IO in order to completely reset the
chip. Also, current consumed from VCC_IO is low and therefore it has simple driving requirements.
Due to the input protection diodes not allowing the digital inputs to rise above VCC_IO level, all
inputs must be driven low during this reset operation. When this is not possible, an input protection
resistor may be used to limit current flowing into the related inputs.
11 Clock Oscillator
The clock is the timing reference for all functions: the chopper frequency, the blank time, the standstill
power down timing, and the internal step pulse generator etc. The on-chip clock oscillator is not
calibrated, but relatively temperature-stable. The internal clock frequency is roughly 12MHz. When the
internal pulse generator is used, and increased precision is desired, measure the internal frequency by
doing a test-motion (with motor disabled) and adapt the pulse frequency to the actual value of the
frequency. Store the calibration value into the microcontroller’s EEPROM for the application.
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TMC7300 DATASHEET (Rev. 1.05 / 2020-Jul-03)
34
12 Absolute Maximum Ratings
The maximum ratings may not be exceeded under any circumstances. Operating the circuit at or near
more than one maximum rating at a time for extended periods shall be avoided by application
design.
Parameter
Supply voltage operating with inductive load *)
Supply and bridge voltage max. *)
I/O supply voltage
digital supply voltage
Logic input voltage
MODE input voltage (Do not exceed both, VCC_IO and
5VOUT by more than 10%, as this enables a test mode)
Maximum current to / from digital pins
and analog low voltage I/Os
1.8V regulator output current (internal plus external load)
Maximum mean or DC current per bridge MOS at TJ
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