TI1 DRV8872DDA Brushed dc motor driver with fault reporting (pwm control) Datasheet

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DRV8872
SLVSCZ0B – AUGUST 2015 – REVISED JANUARY 2016
DRV8872 3.6-A Brushed DC Motor Driver With Fault Reporting (PWM Control)
1 Features
3 Description
•
The DRV8872 is a brushed-DC motor driver for
printers, appliances, industrial equipment, and other
small machines. Two logic inputs control the H-bridge
driver, which consists of four N-channel MOSFETs
that can control motors bidirectionally with up to 3.6-A
peak current. The inputs can be pulse-width
modulated (PWM) to control motor speed, using a
choice of current-decay modes. Setting both inputs
low enters a low-power sleep mode.
1
•
•
•
•
•
•
•
•
•
H-Bridge Motor Driver
– Drives One DC Motor, One Winding of a
Stepper Motor, or Other Loads
Wide 6.5-V to 45-V Operating Voltage
565-mΩ Typical RDS(on) (HS + LS)
3.6-A Peak Current Drive
PWM Control Interface
Integrated Current Regulation
Low-Power Sleep Mode
Fault Status Output Pin
Small Package and Footprint
– 8-Pin HSOP With PowerPAD™
– 4.9 × 6.0 mm
Integrated Protection Features
– VM Undervoltage Lockout (UVLO)
– Overcurrent Protection (OCP)
– Thermal Shutdown (TSD)
– Fault Reporting (nFAULT)
– Automatic Fault Recovery
The DRV8872 features integrated current regulation,
based on an internal reference voltage and the
voltage on pin ISEN, which is proportional to motor
current through an external sense resistor. The ability
to limit current to a known level can significantly
reduce the system power requirements and bulk
capacitance needed to maintain stable voltage,
especially for motor startup and stall conditions.
The device is fully protected from faults and short
circuits, including under-voltage (UVLO), over-current
(OCP), and over-temperature (TSD). Faults are
communicated by pulling the nFAULT output low.
When the fault condition is removed, the device
automatically resumes normal operation.
Device Information
2 Applications
•
•
•
•
PART NUMBER
Printers
Appliances
Industrial Equipment
Other Mechatronic Applications
DRV8872
PACKAGE
HSOP (8)
(1)
BODY SIZE (NOM)
4.90 mm × 6.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
SPACE
Simplified Schematic
H-Bridge States
6.5 to 45 V
IN1
IN2
Controller
nFAULT
DRV8872
3.6 A
Brushed DC
Motor Driver
Current
Regulation
BDC
ISEN
Fault
Protection and
Reporting
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.
DRV8872
SLVSCZ0B – AUGUST 2015 – REVISED JANUARY 2016
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
3
6.1
6.2
6.3
6.4
6.5
6.6
3
4
4
4
5
6
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 7
7.1
7.2
7.3
7.4
Overview ................................................................... 7
Functional Block Diagram ......................................... 7
Feature Description................................................... 8
Device Functional Modes........................................ 10
8
Application and Implementation ........................ 11
8.1 Application Information............................................ 11
8.2 Typical Application .................................................. 11
9
Power Supply Recommendations...................... 14
9.1 Bulk Capacitance .................................................... 14
10 Layout................................................................... 15
10.1 Layout Guidelines .................................................
10.2 Layout Example ....................................................
10.3 Thermal Considerations.......................................
10.4 Power Dissipation .................................................
15
15
15
15
11 Device and Documentation Support ................. 17
11.1
11.2
11.3
11.4
11.5
Documentation Support ........................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
17
17
17
17
17
12 Mechanical, Packaging, and Orderable
Information ........................................................... 17
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (August 2015) to Revision B
Page
•
Updated the ƒPWM max value and added a note .................................................................................................................... 4
•
Removed the redundant TA condition and added ƒPWM = 24 kHz .......................................................................................... 5
•
Added more information to clarify how the max RMS current varies for different applications ........................................... 12
Changes from Original (August 2015) to Revision A
•
2
Page
Updated conditions for Figure 12 ........................................................................................................................................ 13
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5 Pin Configuration and Functions
DDA Package
8-Pin HSOP
Top View
GND
1
IN2
2
IN1
3
nFAULT
4
Thermal
Pad
8
OUT2
7
ISEN
6
OUT1
5
VM
Pin Functions
PIN
NAME
NO.
GND
1
IN1
3
IN2
2
ISEN
7
nFAULT
4
OUT1
6
OUT2
8
PAD
VM
TYPE
DESCRIPTION
PWR
Logic ground
Connect to board ground.
I
Logic inputs
Controls the H-bridge output. Has internal pulldowns. (See Table 1.)
PWR
High-current ground path
If using current regulation, connect ISEN to a resistor (low-value,
high-power-rating) to ground. If not using current regulation, connect
ISEN directly to ground.
OD
Fault status (open-drain)
Low-level indicates UVLO, TSD, or OCP fault. Connect to a pullup
resistor.
O
H-bridge output
Connect directly to the motor, or other inductive load.
—
—
Thermal pad
Connect to board ground. For good thermal dissipation, use large
ground planes on multiple layers, and multiple nearby vias
connecting those planes.
5
PWR
6.5-V to 45-V power
supply
Connect a 0.1-µF bypass capacitor to ground, as well as sufficient
bulk capacitance, rated for the VM voltage.
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)
(1)
MIN
MAX
–0.3
50
V
0
2
V/µs
Logic input voltage (IN1, IN2)
–0.3
7
V
Fault pin (nFAULT)
–0.3
6
V
Continuous phase node pin voltage (OUT1, OUT2)
–0.7
VM + 0.7
V
–0.5
1
V
Operating junction temperature, TJ
–40
150
°C
Storage temperature, Tstg
–65
150
°C
Power supply voltage (VM)
Power supply voltage ramp rate (VM)
Current sense input pin voltage (ISEN)
(1)
(2)
(2)
UNIT
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
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6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
(1)
Charged-device model (CDM), per JEDEC specification JESD22-C101
UNIT
±6000
(2)
V
±750
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
NOM
MAX
VM
Power supply voltage
6.5
45
VI
Logic input voltage (IN1, IN2)
0
5.5
fPWM
Logic input PWM frequency (IN1, IN2)
0
Ipeak
Peak output current
TA
Operating ambient temperature
(1)
(2)
(2)
200
(1)
UNIT
V
V
kHz
0
3.6
A
-40
125
°C
The voltages applied to the inputs should have at least 800 ns of pulse width to ensure detection. Typical devices require at least
400 ns. If the PWM frequency is 200 kHz, the usable duty cycle range is 16% to 84%
Power dissipation and thermal limits must be observed
6.4 Thermal Information
DRV8872
THERMAL METRIC
(1)
DDA (HSOP)
UNIT
8 PINS
RθJA
Junction-to-ambient thermal resistance
41.1
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
53.1
°C/W
RθJB
Junction-to-board thermal resistance
23.1
°C/W
ψJT
Junction-to-top characterization parameter
8.2
°C/W
ψJB
Junction-to-board characterization parameter
23
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
2.7
°C/W
(1)
4
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
TA = 25°C, over recommended operating conditions (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
POWER SUPPLY (VM)
VM
VM operating voltage
IVM
VM operating supply current
VM = 12 V
VM sleep current
VM = 12 V
Turn-on time
VM > VUVLO with IN1 or IN2 high
IVMSLEEP
tON
(1)
6.5
3
40
45
V
10
mA
10
µA
50
µs
0.5
V
LOGIC-LEVEL INPUTS (IN1, IN2)
VIL
Input logic low voltage
VIH
Input logic high voltage
VHYS
Input logic hysteresis
IIL
Input logic low current
VIN = 0 V
IIH
Input logic high current
VIN = 3.3 V
RPD
Pulldown resistance
To GND
100
tPD
Propagation delay
INx to OUTx change (see Figure 6)
0.7
1
μs
tsleep
Time to sleep
Inputs low to sleep
1
1.5
ms
1.5
V
0.5
-1
V
μA
1
33
μA
100
kΩ
MOTOR DRIVER OUTPUTS (OUT1, OUT2)
RDS(ON)
High-side FET on resistance
VM = 24 V, I = 1 A, fPWM = 25 kHz
307
360
mΩ
RDS(ON)
Low-side FET on resistance
VM = 24 V, I = 1 A, fPWM = 25 kHz
258
320
mΩ
tDEAD
Output dead time
Vd
Body diode forward voltage
220
IOUT = 1 A
ns
0.8
1
V
0.35
0.38
V
CURRENT REGULATION
VTRIP
ISEN voltage for current
chopping
tOFF
PWM off-time
tBLANK
PWM blanking time
0.32
25
μs
2
µs
PROTECTION CIRCUITS
VUVLO
VM undervoltage lockout
VUV,HYS
VM undervoltage hysteresis
IOCP
Overcurrent protection trip
level
tOCP
Overcurrent deglitch time
tRETRY
Overcurrent retry time
TSD
Thermal shutdown
temperature
THYS
Thermal shutdown hysteresis
VM falls until UVLO triggers
6.1
6.4
VM rises until operation recovers
6.3
6.5
Rising to falling threshold
100
180
3.7
4.5
150
V
mV
6.4
A
1.5
μs
3
ms
175
°C
40
°C
nFAULT OPEN DRAIN OUTPUT
VOL
Output low voltage
IO = 5 mA
IOH
Output high leakage current
VO = 3.3 V
(1)
0.5
V
1
µA
tON applies when the device initially powers up, and when it exits sleep mode.
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6.6 Typical Characteristics
0.37
1.5
1.4
0.36
1.3
V T R IP ( V )
N o r m a liz e d R D S ( o n ) / R D S ( o n ) _ 2 5 q C
1.6
1.2
1.1
0.35
1
0.34
0.9
0.8
0.7
-40
0.33
-20
0
20
40
60
80
100
120
Ambient Temperature (qC)
140
-40
-20
0
20
40
60
80
100
Temperature (°C)
D001
Figure 1. RDS(on) vs Temperature
120
140
D003
Figure 2. VTRIP vs Temperature
10
IV M S L E E P (µ A )
8
6
4
2
0
0
5
10
15
20
25
30
35
VM (V)
40
45
D004
Figure 3. IVMSLEEP vs VM at 25°C
6
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7 Detailed Description
7.1 Overview
The DRV8872 is an optimized 8-pin device for driving brushed DC motors with 6.5 to 45 V and up to 3.6-A peak
current. The integrated current regulation restricts motor current to a predefined maximum. Two logic inputs
control the H-bridge driver, which consists of four N-channel MOSFETs that have a typical Rds(on) of 565 mΩ
(including one high-side and one low-side FET). A single power input, VM, serves as both device power and the
motor winding bias voltage. The integrated charge pump of the device boosts VM internally and fully enhances
the high-side FETs. Motor speed can be controlled with pulse-width modulation, at frequencies between 0 to 100
kHz. The device has an integrated sleep mode that is entered by bringing both inputs low. An assortment of
protection features prevent the device from being damaged if a system fault occurs.
7.2 Functional Block Diagram
Power
VM
bulk
VCP
VCP
VM
Charge
Pump
0.1 µF
VM
Gate
Driver
OUT1
OCP
GND
PPAD
VCP
IN1
BDC
VM
Gate
Driver
Core
Logic
OUT2
OCP
IN2
ISEN
+
nFAULT
-
RSENSE
VTRIP
Protection Features
Overcurrent
Monitoring
Temperature
Sensor
Voltage
Monitoring
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7.3 Feature Description
7.3.1 Bridge Control
The DRV8872 output consists of four N-channel MOSFETs that are designed to drive high current. They are
controlled by the two logic inputs IN1 and IN2, according to Table 1.
Table 1. H-Bridge Control
IN1
IN2
OUT1
OUT2
0
0
High-Z
High-Z
DESCRIPTION
0
1
L
H
Reverse (current OUT2 → OUT1)
1
0
H
L
Forward (current OUT1 → OUT2)
1
1
L
L
Brake; low-side slow decay
Coast; H-bridge disabled to High-Z (sleep entered after 1 ms)
The inputs can be set to static voltages for 100% duty cycle drive, or they can be pulse-width modulated (PWM)
for variable motor speed. When using PWM, it typically works best to switch between driving and braking. For
example, to drive a motor forward with 50% of its max RPM, IN1 = 1 and IN2 = 0 during the driving period, and
IN1 = 1 and IN2 = 1 during the other period. Alternatively, the coast mode (IN1 = 0, IN2 = 0) for fast current
decay is also available. The input pins can be powered before VM is applied.
VM
VM
1 Reverse drive
1 Forward drive
2 Slow decay (brake)
2 Slow decay (brake)
1
OUT1
1
3 High-Z (coast)
OUT2
OUT1
3 High-Z (coast)
OUT2
2
2
3
3
FORWARD
REVERSE
Figure 4. H-Bridge Current Paths
7.3.2 Sleep Mode
When IN1 and IN2 are both low for time tSLEEP (typically 1 ms), the DRV8872 enters a low-power sleep mode,
where the outputs remain High-Z and the device uses IVMSLEEP (microamps) of current. If the device is powered
up while both inputs are low, sleep mode is immediately entered. After IN1 or IN2 are high for at least 5 µs, the
device will be operational 50 µs (tON) later.
7.3.3 Current Regulation
The DRV8872 limits the output current based on the resistance of an external sense resistor on pin ISEN,
according to this equation:
8
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ITRIP (A)
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VTRIP (V)
RISEN (:)
0.35 (V)
RISEN (:)
(1)
For example, if RISEN = 0.16 Ω, the DRV8872 will limit motor current to 2.2 A no matter how much load torque is
applied. For guidelines on selecting a sense resistor, see Sense Resistor .
When ITRIP has been reached, the device enforces slow current decay by enabling both low-side FETs, and it
does this for time tOFF (typically 25 µs).
Motor Current (A)
ITRIP
tBLANK
tDRIVE
tOFF
Figure 5. Current Regulation Time Periods
After tOFF has elapsed, the output is re-enabled according to the two inputs INx. The drive time (tDRIVE) until
reaching another ITRIP event heavily depends on the VM voltage, the motor’s back-EMF, and the motor’s
inductance.
7.3.4 Dead Time
When an output changes from driving high to driving low, or driving low to driving high, dead time is automatically
inserted to prevent shoot-through. tDEAD is the time in the middle when the output is High-Z. If the output pin is
measured during tDEAD, the voltage will depend on the direction of current. If current is leaving the pin, the
voltage will be a diode drop below ground. If current is entering the pin, the voltage will be a diode drop above
VM. This diode is the body diode of the high-side or low-side FET.
IN1
IN2
OUT1
tPD
tR
tDEAD
tPD
tF
tDEAD
tPD
tF
tDEAD
tPD
tR
tDEAD
OUT2
Figure 6. Propagation Delay Time
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7.3.5 Protection Circuits
The DRV8872 is fully protected against VM undervoltage, overcurrent, and over temperature events. When the
device is in a protected state, nFAULT is driven low. Once the fault condition is removed, nFAULT becomes a
high-impedance state.
7.3.5.1 VM Undervoltage Lockout (UVLO)
If at any time the voltage on the VM pin falls below the undervoltage lockout threshold voltage, all FETs in the Hbridge will be disabled. Operation will resume when VM rises above the UVLO threshold.
7.3.5.2 Overcurrent Protection (OCP)
If the output current exceeds the OCP threshold IOCP for longer than tOCP, all FETs in the H-bridge are disabled
for a duration of tRETRY. After that, the H-bridge will be re-enabled according to the state of the INx pins. If the
overcurrent fault is still present, the cycle repeats; otherwise normal device operation resumes.
7.3.5.3 Thermal Shutdown (TSD)
If the die temperature exceeds safe limits, all FETs in the H-bridge will be disabled. After the die temperature has
fallen to a safe level, operation automatically resumes.
Table 2. Protection Functionality
FAULT
CONDITION
H-BRIDGE BECOMES
NFAULT BECOMES
RECOVERY
VM undervoltage lockout (UVLO)
VM < VUVLO
Disabled
Low
VM > VUVLO
Overcurrent (OCP)
IOUT > IOCP
Disabled
Low
tRETRY
Thermal Shutdown (TSD)
TJ > 150°C
Disabled
Low
TJ < TSD - T HYS
7.4 Device Functional Modes
The DRV8872 can be used in multiple ways to drive a brushed DC motor.
7.4.1 PWM With Current Regulation
This scheme uses all of the device’s capabilities. ITRIP is set above the normal operating current, and high
enough to achieve an adequate spin-up time, but low enough to constrain current to a desired level. Motor speed
is controlled by the duty cycle of one of the inputs, while the other input is static. Brake/slow decay is typically
used during the off-time.
7.4.2 PWM Without Current Regulation
If current regulation is not needed, pin ISEN should be directly connected to the PCB ground plane. This mode
provides the highest possible peak current: up to 3.6 A for a few hundred milliseconds (depending on PCB
characteristics and the ambient temperature). If current exceeds 3.6 A, the device might reach overcurrent
protection (OCP) or over-temperature shutdown (TSD). If that happens, the device disables and protects itself for
about 3 ms (tRETRY) and then resumes normal operation.
7.4.3 Static Inputs With Current Regulation
IN1 and IN2 can be set high and low for 100% duty cycle drive, and ITRIP can be used to control the motor’s
current, speed, and torque capability.
7.4.4 VM Control
In some systems it is desirable to vary VM as a means of changing motor speed. See Motor Voltage for more
information.
10
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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 DRV8872 is typically used to drive one brushed DC motor.
8.2 Typical Application
GND
3.3 V
OUT2
IN2
Controller
IN1
PU
0.2 Ÿ
ISEN
DRV8872
nFAULT
BDC
OUT1
VM
PPAD
0.1 µF
47 µF
+
±
6.5 to 45 V
Power Supply
Figure 7. Typical Connections
8.2.1 Design Requirements
Table 3 lists the design parameters.
Table 3. Design Parameters
DESIGN PARAMETER
Motor voltage
Motor RMS current
Motor startup current
REFERENCE
EXAMPLE VALUE
VM
24 V
IRMS
0.8 A
ISTART
2A
Motor current trip point
ITRIP
2.2 A
Sense resistance
RISEN
0.16 Ω
PWM frequency
fPWM
5 kHz
8.2.2 Detailed Design Procedure
8.2.2.1 Motor Voltage
The motor voltage to use will depend on the ratings of the motor selected and the desired RPM. A higher voltage
spins a brushed DC motor faster with the same PWM duty cycle applied to the power FETs. A higher voltage
also increases the rate of current change through the inductive motor windings.
8.2.2.2 Drive Current
The current path is through the high-side sourcing DMOS power driver, motor winding, and low-side sinking
DMOS power driver. Power dissipation losses in one source and sink DMOS power driver are shown in the
following equation.
PD
I2 RDS(on)Source
RDS(on)Sink
(2)
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The DRV8872 has been measured to be capable of 2-A RMS current at 25°C on standard FR-4 PCBs. The max
RMS current varies based on the PCB design, ambient temperature, and PWM frequency. Typically, switching
the inputs at 200 kHz compared to 20 kHz causes 20% more power loss in heat.
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 IRMS 2 × R. For example, if peak motor current is 3 A, RMS
motor current is 1.5 A, and a 0.2-Ω sense resistor is used, the resistor will dissipate 1.5 A2 × 0.2 Ω = 0.45 W.
The power quickly increases with higher 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, the system
designer should add margin. It is always best to measure the actual sense resistor temperature in a final system.
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.
8.2.3 Application Curves
Figure 8. Current Ramp With a 2-Ω, 1 mH,
RL Load and VM = 12 V
12
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Figure 9. Current Ramp With a 2-Ω, 1 mH,
RL Load and VM = 24 V
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Figure 10. Current Ramp With a 2-Ω, 1 mH,
RL Load and VM = 45 V
Figure 11. tPD
Figure 12. Current Regulation With RSENSE = 0.26 Ω
Figure 13. OCP With 24 V and Outputs Shorted Together
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9 Power Supply Recommendations
9.1 Bulk Capacitance
Having appropriate local bulk capacitance is an important factor in motor drive system design. It is generally
beneficial to have more bulk capacitance, while the disadvantages are increased cost and physical size.
The amount of local capacitance needed depends on a variety of factors, including:
• The highest current required by the motor system
• The power supply’s capacitance and ability to source current
• The amount of parasitic inductance between the power supply and motor system
• The acceptable voltage ripple
• The type of motor used (brushed DC, brushless DC, stepper)
• The 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. When adequate bulk capacitance is used, the motor voltage
remains stable and high current can be quickly supplied.
The data sheet generally provides a recommended value, but system-level testing is required to determine the
appropriate sized bulk capacitor.
Power Supply
Parasitic Wire
Inductance
Motor Drive System
VBB
+
±
+
Motor
Driver
GND
Local
Bulk Capacitor
IC Bypass
Capacitor
Figure 14. Example Setup of Motor Drive System With External Power Supply
The voltage rating for bulk capacitors should be higher than the operating voltage, to provide margin for cases
when the motor transfers energy to the supply.
14
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10 Layout
10.1 Layout Guidelines
The bulk capacitor should be placed to minimize the distance of the high-current path through the motor driver
device. The connecting metal trace widths should be as wide as possible, and numerous vias should be used
when connecting PCB layers. These practices minimize inductance and allow the bulk capacitor to deliver high
current.
Small-value capacitors should be ceramic, and placed closely to device pins.
The high-current device outputs should use wide metal traces.
The device thermal pad should be soldered to the PCB top-layer ground plane. Multiple vias should be used to
connect to a large bottom-layer ground plane. The use of large metal planes and multiple vias help dissipate the
I2 × RDS(on) heat that is generated in the device.
10.2 Layout Example
Recommended layout and component placement is shown in the following diagram.
GND
OUT2
IN2
ISEN
IN1
OUT1
nFAULT
VM
+
Figure 15. Layout Recommendation
10.3
Thermal Considerations
The DRV8872 device has thermal shutdown (TSD) as described in the Thermal Shutdown (TSD) section. If the
die temperature exceeds approximately 175°C, the device is disabled until the temperature drops below the
temperature hysteresis level.
Any tendency of the device to enter TSD is an indication of either excessive power dissipation, insufficient
heatsinking, or too high of an ambient temperature.
10.4 Power Dissipation
Power dissipation in the DRV8872 device is dominated by the power dissipated in the output FET resistance,
RDS(on). Use the equation from the Drive Current section to calculate the estimated average power dissipation of
when driving a load.
Note that at startup, the output current is much higher than normal running current; this peak current and its
duration must be also be considered.
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Power Dissipation (continued)
The maximum amount of power that can be dissipated in the device is dependent on ambient temperature and
heatsinking.
NOTE
RDS(on) increases with temperature, so as the device heats, the power dissipation
increases. This fact must be taken into consideration when sizing the heatsink.
The power dissipation of the DRV8872 is a function of RMS motor current and the FET resistance (RDS(ON)) of
each output.
Power | IRMS2 u High-side RDS(ON)
Low-side RDS(ON)
(3)
For this example, the ambient temperature is 58°C, and the junction temperature reaches 80°C. At 58°C, the
sum of RDS(ON) is about 0.72 Ω. With an example motor current of 0.8 A, the dissipated power in the form of heat
will be 0.8 A2 × 0.72 Ω = 0.46 W.
The temperature that the DRV8872 reaches will depend on the thermal resistance to the air and PCB. It is
important to solder the device PowerPAD to the PCB ground plane, with vias to the top and bottom board layers,
in order dissipate heat into the PCB and reduce the device temperature. In the example used here, the DRV8872
had an effective thermal resistance RθJA of 48°C/W, and:
TJ TA (PD u RTJA ) 58qC (0.46 W u 48qC/W ) 80qC
(4)
10.4.1 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 connection can be accomplished by adding a number of vias to connect the thermal pad to the ground plane.
On PCBs without internal planes, a 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 the TI application report, PowerPAD™ Thermally Enhanced
Package (SLMA002), and the 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.
16
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11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
•
•
•
•
•
PowerPAD™ Thermally Enhanced Package application report, SLMA002
PowerPAD™ Made Easy application brief, SLMA004
Current Recirculation and Decay Modes application report, SLVA321
Calculating Motor Driver Power Dissipation application report, SLVA504
Understanding Motor Driver Current Ratings application report, SLVA505
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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11-Jan-2016
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
DRV8872DDA
ACTIVE SO PowerPAD
DDA
8
75
Green (RoHS
& no Sb/Br)
CU NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
8872
DRV8872DDAR
ACTIVE SO PowerPAD
DDA
8
2500
Green (RoHS
& no Sb/Br)
CU NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
8872
(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)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5)
Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
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11-Jan-2016
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
11-Jan-2016
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
DRV8872DDAR
Package Package Pins
Type Drawing
SO
Power
PAD
DDA
8
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
2500
330.0
12.8
Pack Materials-Page 1
6.4
B0
(mm)
K0
(mm)
P1
(mm)
5.2
2.1
8.0
W
Pin1
(mm) Quadrant
12.0
Q1
PACKAGE MATERIALS INFORMATION
www.ti.com
11-Jan-2016
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
DRV8872DDAR
SO PowerPAD
DDA
8
2500
366.0
364.0
50.0
Pack Materials-Page 2
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