Datasheet

OUT1

OUT2

PWM on

PWM off

VCC

Shown with

IN1=1, IN2=0

DRV8830

www.ti.com

SLVSAB2F –MAY 2010– REVISED FEBRUARY 2012

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 the diagram below as case 1. The current flow direction shown indicates the state when

IN1 is high and IN2 is low.

Note that if the programmed output voltage is greater than the supply voltage, the device will operate at 100%

duty cycle and the voltage regulation feature will be disabled. In this mode the device behaves as a conventional

H-bridge driver.

During the PWM off time, winding current is re-circulated by enabling both of the high-side FETs in the bridge.

This is shown as case 2 below.

Figure 6. Voltage Regulation

Product Folder Link(s): DRV8830