MP6506 –2.7V-TO-15V, 500mA, STEPPER MOTOR DRIVER

MP6506 Rev. 1.0

www.MonolithicPower.com

9

5/22/2014

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OPERATION

The MP6506 is a motor driver that integrates 8

N-channel power MOSFETs for dual, internal full-

bridges with 500mA output current capability over

an input voltage range of 2.7V to 15V. It can

drive a stepper motor, or two DC motors.

The motor output current can be controlled by an

external pulse width modulator (PWM).

The

MP6506

includes

the

following

fault

protections: under-voltage lockout (UVLO) and

over-temperature protection (OTP).

It also provides a low-power sleep mode.

External PWM Current Control

The motor current can be regulated by applying

external PWM signals on the input pins AIN1,

AIN2, BIN1 and BIN2. For phase A, the AIN1 and

AIN2 input pins control the state of the AOUT1

and AOUT2; similarly for phase B, thee BIN1 and

BIN2 input pins control the state of the BOUT1

and BOUT2.

Table 1 shows the input signal logic and bridge

output state.

Table 1: Full-Bridge Gate Logic

A/BIN1

A/BIN2

A/BOUT1

A/BOUT2

L

L

High

Impedance

High

Impedance

L

H

GND

VIN

H

L

VIN

GND

H

H

GND

GND

The winding’s inductive current ramps up when

the high-side MOSFET is on and freewheels

during the high-side MOSFET’s off time to cause

the recirculation current.

There are two modes for this recirculation current:

slow decay and fast decay, both of which are

shown in Figure 2 for forward operation and

Figure 3 for reverse operation.

Figure 2: Forward Operation

Figure 3: Reverse Operation

For slow decay mode, the current circulates

through the two low-side MOSFETs. For fast

decay mode, the current flows through the body

diodes of the other diagonal two MOSFETS.

To configure the MP6506 for fast decay mode,

apply the PWM signal to one input pin and keep

the other input pin low; for slow decay mode,

apply the PWM signal to one input pin and keep

the other input pin high. See Table 2 for more

configuration details and Figure 4 for detailed

waveforms.