Analog Integrated Circuit Device Data

Freescale Semiconductor

9

17550

FUNCTIONAL DESCRIPTION

INTRODUCTION

FUNCTIONAL DESCRIPTION

INTRODUCTION

The 17550 is a monolithic quad H-Bridge ideal for portable

electronic applications containing multiple bipolar stepper

motors and/or brush DC motors. The device features an on-

board DC/DC converter to provide gate-drive voltages, as

well as level-shifting circuitry. The control logic translates the

input signals to the gate-driver circuitry while providing cross-

conduction suppression.

The 17550 has four operating modes: Forward, Reverse,

Brake, and Tri-Stated (High Impedance). The MOSFETs

comprising the output bridge have a total source+sink

The 17550 can simultaneously drive four brush DC motors

or two bipolar stepper motors. The drivers are designed to be

PWM’ed at frequencies up to 200 kHz.

FUNCTIONAL TERMINAL DESCRIPTION

LOGIC SUPPLY (VDD)

The VDD terminal carries the logic supply voltage and

undervoltage threshold. If the supply voltage drops below the

undervoltage threshold, the output power stage switches to a

tri-state condition. When the supply voltage returns to a level

that is above the threshold, the power stage automatically

resumes normal operation according to the established

condition of the input control terminals.

CONTROL SIGNAL INPUT FOR H-BRIDGE,

F=FORWARD, R= REVERSE (INAF, INAR, INBF,

INBR, INCF, INCR, INDF, INDR)

These logic input control terminals control each H-Bridge

output; e.g., IN*F logic HIGH = HB*F HIGH; likewise, IN*R

logic HIGH = HB*R HIGH. However, if both “F” and “R” inputs

are taken HIGH, the associated bridge’s outputs are both tri-

stated (refer to Table 5, Truth Table, page 8).

OUTPUT ENABLE (OE)

OE

terminal is a LOW = TRUE enable input. When

OE

= HIGH, all H-Bridge outputs are tri-stated (high

impedance) regardless of logic inputs states.

OUTPUT OF H-BRIDGE, R=REVERSE,

F=FORWARD (HBAF, HBAR, HBBF, HBBR, HBCF,

HBCR, HBDF, HBDR)

These terminals provide connection to the outputs of each

of the internal H-Bridges (see Figure 2, 17550 Simplified

Internal Block Diagram, page 2).

POWER SUPPLY VOLTAGE CONNECTION FOR

MOTORS A, B, C, D (VMA, VMB, VMC, VMD)

The VM terminals carry the main supply voltage and

current into the power sections of the 17550. This supply then

becomes controlled and/or modulated by the 17550 as it

delivers the power to the loads attached between the

H-Bridge output terminals. All VM terminals must be

connected together on the printed circuit board.

DC/ DC CONVERTER SWITCHING TRANSISTOR

OUTPUT (LX)

The LX terminal is the open-drain output of the internal

DC/DC converter circuit. It is the junction for the external

inductor and the anode of the external Schottky diode.

GATE-DRIVER CIRCUIT POWER SUPPLY (VG)

The VG terminal is the input terminal for the gate-drive

voltage. It can be supplied from the built-in DC/DC converter

or from an external source.

GROUND TERMINALS (GND, AGND, PGND)

All ground terminals must be tied together on the PCB.

POWER STANDBY MODE CONTROL (PSB)

The PSB input controls the functioning of power output

stages (the H-Bridges). When this input signal turns Low, the

output stages and Internal DC/DC Converter which makes

Gate Voltage are disabled and all the outputs are opened

(High Impedance). When this input signal turns High, the

output stages and Internal DC/DC Converter are enabled and

the H-Bridges operate normally.