Analog Integrated Circuit Device Data

8

Freescale Semiconductor

17C724

FUNCTIONAL DESCRIPTION

INTRODUCTION

FUNCTIONAL DESCRIPTION

INTRODUCTION

The 17C724 is a monolithic dual H-Bridge that is ideal in

portable electronic applications to control bipolar step motors

and brush DC motors such as those used in camera lens and

shutters. The 17C724 can operate efficiently with supply

voltages as low as 2.7 V to as high as 5.5 V, and provide

continuous motor drive currents of 0.4 A while handling peak

currents up to 0.8 A. It is easily interfaced to low-cost MCUs

via parallel 3.0 V- or 5.0 V-compatible logic. The device can

be pulse width modulated (PWM’ed) at up to 200 kHz.

The 17C724 can drive two motors simultaneously (see

Figure 6), or it can drive one bipolar step motor as shown in

the simplified application diagram on page 1. Dual channel

parallel drive is also possible if higher current drive is desired

(0.8 A). Two-motor operation is accomplished by hooking

one motor between OUT1A and OUT1B, and the other motor

between OUT2A and OUT2B.

This IC has a built-in shoot-through current protection

circuit and undervoltage detector to avoid malfunction. It also

allows for power-conserving Sleep mode by the setting of the

PSAVE terminal (refer to Table 5, Truth Table, page 7).

The device features four operating modes: Forward,

Reverse, Brake, and Tri-Stated (High Impedance).

FUNCTIONAL TERMINAL DESCRIPTION

LOGIC CIRCUIT POWER SUPPLY (VDD)

The VDD terminal carries the power source connection to

the control (logic) circuit, and its input range is between 2.7 V

below 2.0 V (typical), then all the output of H-Bridges

(OUT1A, OUT1B, OUT2A, OUT2B) will become open (high

impedance = Z). When the supply voltage returns to a level

that is above the threshold voltage the H-Bridge outputs

automatically resume normal operation according to the

established condition of the input terminals.

LOGIC INPUT CONTROL (IN1A, IN1B, IN2A, AND

IN2B)

These logic input terminals control each H-Bridge output.

For example, IN1A logic HIGH = OUT1A HIGH; likewise,

IN1B logic HIGH = OUT1B HIGH. If both A and B inputs are

HIGH, then both A and B outputs are Z (refer to Table 5, Truth

Table, page 7).

INPUT ENABLE CONTROL (PSAVE)

The PSAVE input controls the functioning of the power

output stages (the H-Bridges). When it is set logic LOW, the

output stages are enabled and the H-Bridges function

normally. When it is set logic HIGH, the output stages are

disabled and all the outputs are opened (high impedance). In

this mode, the built-in low-voltage detection circuit is

disabled.

H-BRIDGE OUTPUT (OUT1A, OUT1B, OUT2A, AND

OUT2B)

These terminals are the outputs of the power MOSFET

H-Bridges. OUT1 is from H-Bridge Channel 1, and OUT2

from H-Bridge Channel 2. These terminals will typically

connect to an external load (step motor or brush DC motors).

MOTOR DRIVER POWER SUPPLY (VM1 AND VM2)

VM1 and VM2 carries the main supply voltage and current

into the power sections (the H-Bridges) of the IC. Both of

these terminals are connected internally but they must be

connected together on the printed circuit board with as short

as possible traces. The input range is 2.7 V to 5.5 V.

POWER GROUND (PGND1 AND PGND2)

These two are the power ground terminals that connect to

the power ground of the H-Bridges. The power grounds are

for higher current handling capability from loads and they

must be connected together on the PCB.

LOGIC GROUND (LGND)

LGND is the logic ground terminal and its current handling

level is lower than the PGND.