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DRV8841
SLVSAC0F – MAY 2010 – REVISED DECEMBER 2015
DRV8841 Dual H-Bridge Driver IC
1 Features
2 Applications
•
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•
1
•
•
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Dual H-Bridge DC Motor Driver
– Single and Dual Brushed DC
– Stepper
PWM Control Interface
Optional Fixed Frequency Current Regulation
– Two Bit Current Control Allows Up to Four
Current Levels
Low MOSFET On-Resistance
– 2.5-A Maximum Drive Current at 24 V and
TA = 25°C
– Combined 400 mΩ RDS(ON) of High-Side and
Low-Side at 24 V and TA = 25°C
8.2-V to 45-V Operating Supply Voltage Range
Low Current Sleep Mode
Built-In 3.3-V Reference Output
Thermally Enhanced Surface Mount Package
Protection Features
– Overcurrent Protection (OCP)
– Thermal Shutdown (TSD)
– Undervoltage Lockout (UVLO)
– Fault Condition Indication Pin (nFAULT)
Printers
Scanners
Office Automation Machines
Gaming Machines
Factory Automation
Robotics
3 Description
The DRV8841 provides an integrated dual H-bridge
motor driver solution for printers, scanners, and other
automated equipment applications. The device can
be used to drive one or two brushed DC motors, a
bipolar stepper motor, or other loads. A simple PWM
interface allows easy interfacing to controller circuits.
The output driver block consists of N-channel power
MOSFETs configured as H-bridges. The DRV8841 an
supply up to 2.5-A peak or 1.75-A RMS output
current (with proper heat sinking at 24 V and
TA = 25°C) per H-bridge.
A low-power sleep mode is provided which shuts
down internal circuitry to achieve very low quiescent
current draw. This sleep mode can be set using a
dedicated nSLEEP pin. Internal protection features
are provided for overtemperature, overcurrent, and
undervoltage. Fault conditions are indicated by a
nFAULT pin.
Device Information(1)
PART NUMBER
DRV8841
PACKAGE
HTSSOP (28)
BODY SIZE (NOM)
9.70 mm × 4.40 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
8.2 to 45 V
DRV8841
PWM
2.5 A
Decay Mode
Controller
Current Level
Dual
H-Bridge Motor
Driver
2.5 A
nFAULT
Protection
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
DRV8841
SLVSAC0F – MAY 2010 – REVISED DECEMBER 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
5
6.1
6.2
6.3
6.4
6.5
6.6
5
5
5
5
6
7
Absolute Maximum Ratings ......................................
ESD Ratings ............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 8
7.1
7.2
7.3
7.4
Overview ................................................................... 8
Functional Block Diagram ......................................... 9
Feature Description................................................. 10
Device Functional Modes........................................ 13
8
Application and Implementation ........................ 14
8.1 Application Information............................................ 14
8.2 Typical Application .................................................. 14
9
Power Supply Recommendations...................... 17
9.1 Bulk Capacitance .................................................... 17
9.2 Power Supply and Logic Sequencing ..................... 17
10 Layout................................................................... 18
10.1 Layout Guidelines ................................................. 18
10.2 Layout Example .................................................... 18
10.3 Thermal Considerations ........................................ 18
11 Device and Documentation Support ................. 20
11.1
11.2
11.3
11.4
11.5
Documentation Support ........................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
20
20
20
20
20
12 Mechanical, Packaging, and Orderable
Information ........................................................... 20
4 Revision History
Changes from Revision E (August 2013) to Revision F
Page
•
Added ESD Rating table, Feature Description section, Device Functional Modes, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section ................................................................................................. 1
•
Updated Features section ...................................................................................................................................................... 1
•
Updated Description section................................................................................................................................................... 1
•
Changed the text under the EXTERNAL COMPONENTS OR CONNECTIONS column for the VMA and VMB rows ........ 3
•
Changed MIN value for ISENSEx pin voltage from –0.3 V to –0.8 V..................................................................................... 5
2
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5 Pin Configuration and Functions
PWP Package
28 Pin HTSSOP
Top View
CP1
CP2
VCP
VMA
AOUT1
ISENA
AOUT2
BOUT2
ISENB
BOUT1
VMB
AVREF
BVREF
GND
1
28
2
27
3
26
4
25
5
24
6
23
GND
(PowerPAD)
7
8
22
21
9
20
10
19
11
18
12
17
13
16
14
15
GND
BI1
BI0
AI1
AI0
BIN2
BIN1
AIN1
AIN2
DECAY
nFAULT
nSLEEP
nRESET
V3P3OUT
Pin Functions
PIN
NAME
NO.
I/O (1)
EXTERNAL COMPONENTS
OR CONNECTIONS
DESCRIPTION
POWER AND GROUND
GND
14, 28
—
Device ground
VMA
4
—
Bridge A power supply
VMB
11
—
Bridge B power supply
V3P3OUT
15
O
3.3-V regulator output
CP1
1
IO
Charge pump flying capacitor
CP2
2
IO
Charge pump flying capacitor
VCP
3
IO
High-side gate drive voltage
Connect a 0.1-μF 16-V ceramic capacitor and
a 1-MΩ resistor to VM.
AIN1
21
I
Bridge A input 1
Logic input controls state of AOUT1. Internal
pulldown.
AIN2
20
I
Bridge A input 2
Logic input controls state of AOUT2. Internal
pulldown.
AI0
24
I
Bridge A current set
Sets bridge A current: 00 = 100%,
01 = 71%, 10 = 38%, 11 = 0
Internal pulldown.
Connect to motor supply (8.2 V to 45 V). Both
pins must be connected to the same supply,
bypassed with a 0.1-uF capacitor to GND, and
connected to appropriate bulk capacitance.
Bypass to GND with a 0.47-μF 6.3-V ceramic
capacitor. Can be used to supply VREF.
Connect a 0.01-μF 50-V capacitor between
CP1 and CP2.
CONTROL
AI1
25
I
BIN1
22
I
Bridge B input 1
Logic input controls state of BOUT1. Internal
pulldown.
BIN2
23
I
Bridge B input 2
Logic input controls state of BOUT2. Internal
pulldown.
BI0
26
I
Bridge B current set
Sets bridge B current: 00 = 100%,
01 = 71%, 10 = 38%, 11 = 0
Internal pulldown.
BI1
(1)
27
I
Directions: I = input, O = output, OZ = tri-state output, OD = open-drain output, IO = input/output
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Pin Functions (continued)
PIN
I/O (1)
DESCRIPTION
EXTERNAL COMPONENTS
OR CONNECTIONS
NAME
NO.
DECAY
19
I
Decay mode
Low = slow decay, open = mixed decay,
high = fast decay. Internal pulldown and
pullup.
nRESET
16
I
Reset input
Active-low reset input initializes internal logic
and disables the H-bridge outputs. Internal
pulldown.
nSLEEP
17
I
Sleep mode input
Logic high to enable device, logic low to enter
low-power sleep mode. Internal pulldown.
AVREF
12
I
Bridge A current set reference input
BVREF
13
I
Bridge B current set reference input
18
OD
Fault
Logic low when in fault condition
(overtemperature, overcurrent)
ISENA
6
IO
Bridge A ground / Isense
Connect to current sense resistor for bridge A
ISENB
9
IO
Bridge B ground / Isense
Connect to current sense resistor for bridge B
AOUT1
5
O
Bridge A output 1
AOUT2
7
O
Bridge A output 2
BOUT1
10
O
Bridge B output 1
BOUT2
8
O
Bridge B output 2
Reference voltage for winding current set.
Can be driven individually with an external
DAC for microstepping, or tied to a reference
(for example, V3P3OUT).
STATUS
nFAULT
OUTPUT
4
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Connect to motor winding A
Connect to motor winding B
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)
VMx
VREF
(1)
Power supply voltage
MIN
MAX
UNIT
–0.3
47
V
Power supply ramp rate
1
V/µs
Digital pin voltage
–0.5
7
V
Input voltage
–0.3
4
V
–0.8
ISENSEx pin voltage
(2)
0.8
V
Peak motor drive output current, t < 1 μS
Internally limited
A
Continuous motor drive output current (3)
0
A
Continuous total power dissipation
2.5
See Thermal Information
TJ
Operating virtual junction temperature
–40
150
°C
TA
Operating ambient temperature
–40
85
°C
Tstg
Storage temperature
–60
150
°C
(1)
(2)
(3)
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Transients of ±1 V for less than 25 ns are acceptable.
Power dissipation and thermal limits must be observed.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1)
±2000
Charged device model (CDM), per JEDEC specification JESD22-C101, all
pins (2)
±500
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
VM
Motor power supply voltage (1)
VREF
NOM
MAX
UNIT
8.2
45
VREF input voltage (2)
1
3.5
IV3P3
V3P3OUT load current
0
1
mA
fPWM
Externally applied PWM frequency
0
100
kHz
(1)
(2)
V
V
All VM pins must be connected to the same supply voltage.
Operational at VREF from 0 V to 1 V, but accuracy is degraded.
6.4 Thermal Information
DRV8841
THERMAL METRIC
(1)
PWP (HTSSOP)
UNIT
28 PINS
RθJA
Junction-to-ambient thermal resistance
31.6
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
15.9
°C/W
RθJB
Junction-to-board thermal resistance
5.6
°C/W
ψJT
Junction-to-top characterization parameter
0.2
°C/W
ψJB
Junction-to-board characterization parameter
5.5
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
1.4
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
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6.5 Electrical Characteristics
over operating free-air temperature range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
POWER SUPPLIES
IVM
VM operating supply current
VM = 24 V, fPWM < 50 kHz
5
8
mA
IVMQ
VM sleep mode supply current
VM = 24 V
10
20
μA
VUVLO
VM undervoltage lockout voltage
VM rising
7.8
8.2
V
3.3
3.4
V
V3P3OUT REGULATOR
V3P3
V3P3OUT voltage
IOUT = 0 to 1 mA
3.2
LOGIC-LEVEL INPUTS
VIL
Input low voltage
VIH
Input high voltage
2.2
0.6
VHYS
Input hysteresis
0.3
IIL
Input low current
VIN = 0
IIH
Input high current
VIN = 3.3 V
RPD
Internal pulldown resistance
0.45
–20
0.7
V
5.25
V
0.6
V
20
μA
100
100
μA
kΩ
nFAULT OUTPUT (OPEN-DRAIN OUTPUT)
VOL
Output low voltage
IO = 5 mA
IOH
Output high leakage current
VO = 3.3 V
0.5
V
1
μA
0.8
V
±40
μA
DECAY INPUT
VIL
Input low threshold voltage
For slow decay (brake) mode
0
VIH
Input high threshold voltage
For fast decay (coast) mode
2
IIN
Input current
RPU
Internal pullup resistance
RPD
Internal pulldown resistance
V
130
kΩ
80
kΩ
H-BRIDGE FETS
RDS(ON)
HS FET on resistance
RDS(ON)
LS FET on resistance
IOFF
Off-state leakage current
VM = 24 V, IO = 1 A, TJ = 25°C
0.2
VM = 24 V, IO = 1 A, TJ = 85°C
0.25
VM = 24 V, IO = 1 A, TJ = 25°C
0.2
VM = 24 V, IO = 1 A, TJ = 85°C
0.25
–20
0.32
0.32
20
Ω
Ω
μA
MOTOR DRIVER
fPWM
Internal current control PWM
frequency
tBLANK
Current sense blanking time
tR
Rise time
30
200
ns
tF
Fall time
30
200
ns
160
180
°C
3
μA
50
kHz
μs
3.75
PROTECTION CIRCUITS
IOCP
Overcurrent protection trip level
tTSD
Thermal shutdown temperature
3
Die temperature
150
A
CURRENT CONTROL
IREF
VREF input current
VTRIP
xISENSE trip voltage
AISENSE
Current sense amplifier gain
6
VREF = 3.3 V
–3
xVREF = 3.3 V, 100% current setting
635
660
685
xVREF = 3.3 V, 71% current setting
445
469
492
xVREF = 3.3 V, 38% current setting
225
251
276
Reference only
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5
mV
V/V
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6.6 Typical Characteristics
7
14
6.5
12
IVMQ (PA)
IVM (mA)
6
5.5
10
5
8
-40qC
25qC
85qC
125qC
4.5
4
10
15
20
25
30
V(VMx) (V)
35
40
6
10
45
-40qC
25qC
85qC
125qC
15
Figure 1. IVMx vs V(VMx)
25
30
V(VMx) (V)
35
40
45
D002
Figure 2. IVMxQ vs V(VMx)
750
750
-40qC
25qC
85qC
125qC
700
RDS(ON) HS + LS (m:)
700
RDS(ON) HS + LS (m:)
20
D001
650
600
550
500
450
650
600
550
500
8V
24 V
45 V
450
400
8
13
18
23
28
V(VMx) (V)
33
38
400
-50
43
D003
Figure 3. RDS(ON) vs V(VMx)
-25
0
25
50
TA (qC)
75
100
125
D004
Figure 4. RDS(ON) vs Temperature
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7 Detailed Description
7.1 Overview
The DRV8841 is an integrated motor driver solution for two brushed DC motors or a bipolar stepper motor. The
device integrates two power NMOS H-bridges, current sense and regulation circuitry, protection devices, and a
digital interface.
A simple PWM interface allows for easy interfacing to an external digital controller and requires minimal
resources. The fault indication pin (nFAULT) provides a flag for when the device has entered a fault state.
The current regulation is highly configurable with three modes of operation. Depending on the applications
requirements the device can be configured for fast, slow, or mixed decay. Two bit current level control allows the
device to switch between four different current levels. A low-power sleep mode is implemented which allows the
system to save power when not driving the motor.
8
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7.2 Functional Block Diagram
Vcc
LS Gate
Drive
HS Gate
Drive
Low-Side
LDO
Charge
Pump
VM
VCP
+
3.3V
V3P3OUT
3.3V
3.3V
LDO
VM
Bulk
Capacitor
CP1
Internal
Logic
LDO
AVREF
CP2
VM
AVREF
VMA
LS Gate HS Gate
Drive
Drive
BVREF
Vcc
BVREF
AIN1
AOUT1
AIN2
AI0
Gate
Drive
BDC
Motor
VM
AI1
AOUT2
BIN1
AVREF
BIN2
ISENA
ISENA
BI0
LS Gate HS Gate
Drive
Drive
Control
Logic
BI1
VM
RSENSE
(optional)
VM
Stepper
Motor
VMB
nRESET
BOUT1
nSLEEP
V3P3OUT
Gate
Drive
DECAY
BDC
Motor
VM
nFAULT
BOUT2
BVREF
Thermal
Sensor
ISENB
GND
PPAD
ISENB
RSENSE
(optional)
GND
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7.3 Feature Description
7.3.1 PWM Motor Drivers
The DRV8841 contains two H-bridge motor drivers with current-control PWM circuitry. A block diagram of the
motor control circuitry is shown in Figure 5.
VM
OCP
VM
VCP, VGD
AOUT1
Predrive
AIN1
DCM
AIN2
AOUT2
DECAY
PWM
OCP
AISEN
+
AI[1:0]
A=5
DAC
2
AVREF
VM
OCP
VM
VCP, VGD
BOUT1
Predrive
BIN1
DCM
BIN2
BOUT2
PWM
OCP
BISEN
+
BI[1:0]
A =5
DAC
2
BVREF
Figure 5. Motor Control Circuitry
Note that there are multiple VM pins. All VM pins must be connected together to the motor supply voltage.
10
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Feature Description (continued)
7.3.2 Blanking Time
After the current is enabled in an H-bridge, the voltage on the xISEN pin is ignored for a fixed period of time
before enabling the current sense circuitry. This blanking time is fixed at 3.75 μs. Note that the blanking time also
sets the minimum on time of the PWM.
7.3.3 Bridge Control
The AIN1 and AIN2 input pins directly control the state of the AOUT1 and AOUT2 outputs; similarly, the BIN1
and BIN2 input pins directly control the state of the BOUT1 and BOUT2 outputs. Either input can also be used
for PWM control of the load. Table 1 shows the logic.
Table 1. H-Bridge Logic
xIN1
xIN2
xOUT1
xOUT2
0
0
L
L
0
1
L
H
1
0
H
L
1
1
H
H
The control inputs have internal pulldown resistors of approximately 100 kΩ.
7.3.4 Current Regulation
The current through the motor windings is regulated by a fixed-frequency PWM current regulation, or current
chopping. When an H-bridge is enabled, current rises through the winding at a rate dependent on the DC voltage
and inductance of the winding. Once the current hits the current chopping threshold, the bridge disables the
current until the beginning of the next PWM cycle.
For stepping motors, current regulation is normally used at all times, and can changing the current can be used
to microstep the motor. For DC motors, current regulation is used to limit the start-up and stall current of the
motor.
If the current regulation feature is not needed, it can be disabled by connecting the xISENSE pins directly to
ground and the xVREF pins to V3P3.
The PWM chopping current is set by a comparator which compares the voltage across a current sense resistor
connected to the xISEN pins, multiplied by a factor of 5, with a reference voltage. The reference voltage is input
from the xVREF pins, and is scaled by a 2-bit DAC that allows current settings of 100%, 71%, 38% of full-scale,
plus zero.
The full-scale (100%) chopping current is calculated in Equation 1.
VREFX
ICHOP
5 u RISENSE
(1)
Example:
If a 0.25-Ω sense resistor is used and the VREFx pin is 2.5 V, the full-scale (100%) chopping current will be
2.5 V / (5 × 0.25 Ω) = 2 A.
Two input pins per H-bridge (xI1 and xI0) are used to scale the current in each bridge as a percentage of the fullscale current set by the VREF input pin and sense resistance. The xI0 and xI1 pins have internal pulldown
resistors of approximately 100 kΩ. The function of the pins is shown in Table 2.
Table 2. H-Bridge Pin Functions
xI1
xI0
RELATIVE CURRENT
(% FULL-SCALE CHOPPING CURRENT)
1
1
0% (Bridge disabled)
1
0
38%
0
1
71%
0
0
100%
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Note that when both xI bits are 1, the H-bridge is disabled and no current flows.
Example:
If a 0.25-Ω sense resistor is used and the VREF pin is 2.5 V, the chopping current will be 2 A at the 100%
setting (xI1, xI0 = 00). At the 71% setting (xI1, xI0 = 01) the current will be 2 A × 0.71 = 1.42 A, and at the
38% setting (xI1, xI0 = 10) the current will be 2 A × 0.38 = 0.76 A. If (xI1, xI0 = 11) the bridge will be disabled
and no current will flow.
7.3.5 Decay Mode
During PWM current chopping, the H-bridge is enabled to drive current through the motor winding until the PWM
current chopping threshold is reached. This is shown in Figure 6 as case 1. The current flow direction shown
indicates the state when the xIN1 pin is high and the xIN2 pin is low.
Once the chopping current threshold is reached, the H-bridge can operate in two different states, fast decay or
slow decay.
In fast decay mode, once the PWM chopping current level has been reached, the H-bridge reverses state to
allow winding current to flow in a reverse direction. As the winding current approaches zero, the bridge is
disabled to prevent any reverse current flow. Fast decay mode is shown in Figure 6 as case 2.
In slow decay mode, winding current is recirculated by enabling both of the low-side FETs in the bridge. This is
shown in Figure 6 as case 3.
Figure 6. Decay Mode
The DRV8841 supports fast decay, slow decay and a mixed decay mode. Slow, fast, or mixed decay mode is
selected by the state of the DECAY pin - logic low selects slow decay, open selects mixed decay operation, and
logic high sets fast decay mode. The DECAY pin has both an internal pullup resistor of approximately 130 kΩ
and an internal pulldown resistor of approximately 80 kΩ. This sets the mixed decay mode if the pin is left open
or undriven. Note that the DECAY pin sets the decay mode for both H-bridges.
Mixed decay mode begins as fast decay, but at a fixed period of time (75% of the PWM cycle) switches to slow
decay mode for the remainder of the fixed PWM period.
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7.3.6 Protection Circuits
The DRV8841 is fully protected against undervoltage, overcurrent and overtemperature events.
7.3.6.1 Overcurrent Protection (OCP)
An analog current limit circuit on each FET limits the current through the FET by removing the gate drive. If this
analog current limit persists for longer than the OCP time, all FETs in the H-bridge will be disabled and the
nFAULT pin will be driven low. The device will remain disabled until either nRESET pin is applied, or VM is
removed and reapplied.
Overcurrent conditions on both high and low side devices; that is, a short to ground, supply, or across the motor
winding will all result in an overcurrent shutdown. Note that overcurrent protection does not use the current sense
circuitry used for PWM current control, and is independent of the ISENSE resistor value or VREF voltage.
7.3.6.2 Thermal Shutdown (TSD)
If the die temperature exceeds safe limits, all FETs in the H-bridge will be disabled and the nFAULT pin will be
driven low. Once the die temperature has fallen to a safe level operation will automatically resume.
7.3.6.3 Undervoltage Lockout (UVLO)
If at any time the voltage on the VM pins falls below the undervoltage lockout threshold voltage, all circuitry in the
device will be disabled and internal logic will be reset. Operation will resume when VM rises above the UVLO
threshold.
7.4 Device Functional Modes
7.4.1 nRESET and nSLEEP Operation
The nRESET pin, when driven active low, resets the internal logic. It also disables the H-bridge drivers. All inputs
are ignored while nRESET is active.
Driving nSLEEP low will put the device into a low power sleep state. In this state, the H-bridges are disabled, the
gate drive charge pump is stopped, the V3P3OUT regulator is disabled, and all internal clocks are stopped. In
this state all inputs are ignored until nSLEEP returns inactive high. When returning from sleep mode, some time
(approximately 1 ms) must pass before the motor driver becomes fully operational. Note that nRESET and
nSLEEP have internal pulldown resistors of approximately 100 kΩ. These signals must be driven to logic high for
device operation.
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8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The DRV8841 can be used to control a bipolar stepper motor. The PWM interface controls the outputs and
current control can be implemented with the internal current regulation circuitry. Detailed fault reporting is
provided with the internal protection circuits and nFAULT pin.
8.2 Typical Application
DRV8841
CP1
GND
CP2
BI1
VCP
BI0
VMA
AI1
AOUT1
AI0
0.01uF
1MŸ
0.1uF
+
0.01uF
200mŸ
Stepper
Motor
ISENA
BIN2
AOUT2
BIN1
BOUT2
AIN1
ISENB
AIN2
-
VM
100uF
+
+
-
200mŸ
BOUT1
DECAY
VMB
nFAULT
AVREF
nSLEEP
BVREF
nRESET
V3P3OU
T
10kŸ
0.01uF
V3P3OU
T
30kŸ
GND
PPAD
50kŸ
V3P3OUT
V3P3OU
T
0.47uF
Figure 7. Typical Application Schematic
14
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Typical Application (continued)
8.2.1 Design Requirements
Table 3 lists the design parameters for this design example.
Table 3. Design Parameters
DESIGN PARAMETER
REFERENCE
EXAMPLE VALUE
Supply Voltage
VM
24 V
Motor Winding Resistance
RL
3.9 Ω
Motor Winding Inductance
IL
2.9 mH
RSENSE
200 mΩ
IFS
1.25 A
Sense Resistor Value
Target Full-Scale Current
8.2.2 Detailed Design Procedure
8.2.2.1 Current Regulation
In a stepper motor, the set full-scale current (IFS) is the maximum current driven through either winding. This
quantity depends on the xVREF analog voltage and the sense resistor value (RSENSE). During stepping, IFS
defines the current chopping threshold (ITRIP) for the maximum current step. The gain of DRV8841 is set for 5
V/V.
xVREF(V)
xVREF(V)
IFS (A)
A v u RSENSE (:) 5 u RSENSE (:)
(2)
To achieve IFS = 1.25 A with RSENSE of 0.2 Ω, xVREF should be 1.25 V.
8.2.2.2 Decay Modes
The DRV8841 supports three different decay modes: slow decay, fast decay, and mixed decay. The current
through the motor windings is regulated using a fixed-frequency PWM scheme. This means that after any drive
phase, when a motor winding current has hit the current chopping threshold (ITRIP), the DRV8841 will place the
winding in one of the three decay modes until the PWM cycle has expired. Afterward, a new drive phase starts.
The blanking time, tBLANK, defines the minimum drive time for the current chopping. ITRIP is ignored during tBLANK,
so the winding current may overshoot the trip level.
8.2.2.3 Sense Resistor
For optimal performance, it is important for the sense resistor to be:
• Surface-mount
• Low inductance
• Rated for high enough power
• Placed closely to the motor driver
The power dissipated by the sense resistor equals Irms2 × R. For example, if the rms motor current is 2-A and a
100-mΩ sense resistor is used, the resistor will dissipate 2 A2 × 0.1 Ω = 0.4 W. The power quickly increases with
greater current levels.
Resistors typically have a rated power within some ambient temperature range, along with a derated power curve
for high ambient temperatures. When a PCB is shared with other components generating heat, margin should be
added. It is always best to measure the actual sense resistor temperature in a final system, along with the power
MOSFETs, as those are often the hottest components.
Because power resistors are larger and more expensive than standard resistors, it is common practice to use
multiple standard resistors in parallel, between the sense node and ground. This distributes the current and heat
dissipation.
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8.2.3 Application Curves
Figure 8. Start-Up
16
Figure 9. Current-Limiting
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9 Power Supply Recommendations
The DRV8841 is designed to operate from an input voltage supply (VMx) range from 8.2 to 45 V. Two
0.1-µF ceramic capacitors rated for VMx must be placed as close as possible to the VMA and VMB pins
respectively (one on each pin). In addition to the local decoupling caps, additional bulk capacitance is required
and must be sized accordingly to the application requirements.
9.1 Bulk Capacitance
Bulk capacitance sizing is an important factor in motor drive system design. It is dependent on a variety of factors
including:
• Type of power supply
• Acceptable supply voltage ripple
• Parasitic inductance in the power supply wiring
• Type of motor (brushed DC, brushless DC, stepper)
• Motor start-up current
• Motor braking method
The inductance between the power supply and motor drive system will limit the rate current can change from the
power supply. If the local bulk capacitance is too small, the system will respond to excessive current demands or
dumps from the motor with a change in voltage. You should size the bulk capacitance to meet acceptable
voltage ripple levels.
The data sheet generally provides a recommended value but system level testing is required to determine the
appropriate sized bulk capacitor.
Parasitic Wire
Inductance
Motor Drive System
Power Supply
VM
+
–
Motor
Motor
Driver
Driver
+
GND
Local
Bulk Capacitor
IC Bypass
Capacitor
Figure 10. Setup of Motor Drive System With External Power Supply
9.2 Power Supply and Logic Sequencing
There is no specific sequence for powering-up the DRV8841. It is okay for digital input signals to be present
before VMx is applied. After VMx is applied to the DRV8841, it begins operation based on the status of the
control pins.
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10 Layout
10.1 Layout Guidelines
The VMA and VMB pins should be bypassed to GND using low-ESR ceramic bypass capacitors with a
recommended value of 0.1-μF rated for VMx. This capacitor should be placed as close to the VMA and VMB pins
as possible with a thick trace or ground plane connection to the device GND pin.
The VMA and VMB pins must be bypassed to ground using an appropriate bulk capacitor. This component may
be an electrolytic and should be located close to the DRV8841.
A low-ESR ceramic capacitor must be placed in between the CPL and CPH pins. TI recommends a value of
0.01-μF rated for VMx. Place this component as close to the pins as possible.
A low-ESR ceramic capacitor must be placed in between the VMA and VCP pins. TI recommends a value of
0.1-μF rated for 16 V. Place this component as close to the pins as possible. Also, place a 1-MΩ resistor
between VCP and VMA.
Bypass V3P3 to ground with a ceramic capacitor rated 6.3 V. Place this bypass capacitor as close to the pin as
possible
10.2 Layout Example
0.1 µF
CP1
GND
CP2
BI1
VCP
BI0
0.01 µF
1 0Ÿ
0.1 µF
RISENA
RISENB
VMA
AI1
AOUT1
AI0
ISENA
BIN2
AOUT2
BIN1
BOUT2
AIN1
ISENB
AIN2
BOUT1
DECAY
VMB
nFAULT
AVREF
nSLEEP
BVREF
nRESET
GND
V3P3OUT
+
0.1 µF
0.47 µF
Figure 11. Layout Recommendation
10.3 Thermal Considerations
The DRV8841 has thermal shutdown (TSD) as described in Thermal Shutdown (TSD). If the die temperature
exceeds approximately 150°C, the device will be disabled until the temperature drops to a safe level.
Any tendency of the device to enter TSD is an indication of either excessive power dissipation, insufficient
heatsinking, or too high an ambient temperature.
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Thermal Considerations (continued)
10.3.1 Power Dissipation
Power dissipation in the DRV8841 is dominated by the power dissipated in the output FET resistance, or
RDS(ON). Average power dissipation of each H-bridge when running a DC motor can be roughly estimated by
Equation 3.
P
2 u RDS(ON) u IOUT
2
where
•
•
•
P is the power dissipation of one H-bridge
RDS(ON) is the resistance of each FET
IOUT is the RMS output current being applied to each winding
(3)
IOUT is equal to the average current drawn by the DC motor. Note that at start-up and fault conditions this current
is much higher than normal running current; these peak currents and their duration also must be taken into
consideration. The factor of 2 comes from the fact that at any instant two FETs are conducting winding current
(one high-side and one low-side).
The total device dissipation will be the power dissipated in each of the two H-bridges added together.
The maximum amount of power that can be dissipated in the device is dependent on ambient temperature and
heatsinking.
RDS(ON) increases with temperature, so as the device heats, the power dissipation increases. This must be taken
into consideration when sizing the heatsink.
10.3.2 Heatsinking
The PowerPAD™ package uses an exposed pad to remove heat from the device. For proper operation, this pad
must be thermally connected to copper on the PCB to dissipate heat. On a multi-layer PCB with a ground plane,
this can be accomplished by adding a number of vias to connect the thermal pad to the ground plane. On PCBs
without internal planes, copper area can be added on either side of the PCB to dissipate heat. If the copper area
is on the opposite side of the PCB from the device, thermal vias are used to transfer the heat between top and
bottom layers.
For details about how to design the PCB, refer to TI application report, PowerPAD™ Thermally Enhanced
Package (SLMA002), and TI application brief, PowerPAD™ Made Easy (SLMA004), available at www.ti.com.
In general, the more copper area that can be provided, the more power can be dissipated.
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11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
For related documentation see the following:
• PowerPAD™ Thermally Enhanced Package, SLMA002.
• PowerPAD™ Made Easy, SLMA004.
11.2 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.3 Trademarks
PowerPAD, E2E are trademarks of Texas Instruments.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
DRV8841PWP
ACTIVE
HTSSOP
PWP
28
50
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-40 to 85
DRV8841
DRV8841PWPR
ACTIVE
HTSSOP
PWP
28
2000
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-40 to 85
DRV8841
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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