DRV8830_16 Datasheet, PDF (8/22 Pages) Texas Instruments – Low-Voltage Motor Driver With Serial Interface

DRV8830
SLVSAB2G – MAY 2010 – REVISED DECEMBER 2015
7 Detailed Description
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7.1 Overview
The DRV8830 is an integrated motor driver solution used for brushed motor control. The device integrates one
H-bridge, current regulation circuitry, and a PWM voltage regulation method.
Using the PWM voltage regulation allows the motor to maintain the desired speed as VCC changes. Battery
operation is an example of using this feature. When the battery is new or fully charged VCC will be higher than
when the battery is old or partially discharged. The speed of the motor will vary based on the voltage of the
battery. By setting the desired voltage across the motor at a lower voltage, a fully charged battery will use less
power and spin the motor at the same speed as a battery that has been partially discharged.
7.2 Functional Block Diagram
Battery
VCC
VCC
SDA
SCL
A0
A1
FAULTn
Integ.
-
Comp
Ref
DAC +
5
VCC
OCP
Gate
Drive
VCC
Logic
OCP
I2C
Addr
Sel
Over-
Temp
Osc
Gate
Drive
Current
Sense
OUT1
DCM
OUT2
ISENSE
GND
7.3 Feature Description
7.3.1 Voltage Regulation
The DRV8830 provides the ability to regulate the voltage applied to the motor winding. This feature allows
constant motor speed to be maintained even when operating from a varying supply voltage such as a
discharging battery.
The DRV8830 uses a pulse-width modulation (PWM) technique instead of a linear circuit to minimize current
consumption and maximize battery life.
The circuit monitors the voltage difference between the output pins and integrates it, to get an average DC
voltage value. This voltage is divided by 4 and compared to the output voltage of the VSET DAC, which is set
through the serial interface. If the averaged output voltage (divided by 4) is lower than VSET, the duty cycle of
the PWM output is increased; if the averaged output voltage (divided by 4) is higher than VSET, the duty cycle is
decreased.
During PWM regulation, the H-bridge is enabled to drive current through the motor winding during the PWM on
time. This is shown in Figure 8 as case 1. The current flow direction shown indicates the state when IN1 is high
and IN2 is low.
8
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