3972

DUAL DMOS FULL-BRIDGE

MICROSTEPPING PWM MOTOR DRIVER

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

8

Current Sensing. To minimize inaccuracies in sensing the

I

resistor should have an independent ground return to the ground

terminal of the device. For low-value sense resistors, the IR

drops in the sense resistor’s PCB traces can be significant and

should be taken into account. The use of sockets should be

avoided as they can introduce variation in R

contact resistance.

Thermal Protection. Circuitry turns off all drivers when the

junction temperature reaches 165

°C typically. It is intended

only to protect the device from failures due to excessive

junction temperature and should not imply that output short

circuits are permitted. Thermal shutdown has a hysteresis of

approximately 15

°C.

Serial Port Write Timing Operation. Data is clocked into a

shift register on the rising edge of CLOCK signal. Normally,

STROBE will be held high, and only will be brought low to

initiate a write cycle. The data is written MSB first, followed

by the word-select bit. Refer to serial port diagram for timing

requirements.

DATA

CLOCK

Dwg. WP-038-1

STROBE

A

F

B

G

C

D

E

D18

D0

H

SLEEP

D17

APPLICATIONS INFORMATION

A. Minimum Data Setup Time ..................................... 15 ns

B. Minimum Data Hold Time ...................................... 10 ns

C. Minimum Setup Strobe to Clock Rising Edge ...... 150 ns

D. Minimum Clock High Pulse Width ......................... 40 ns

E. Minimum Clock Low Pulse Width ......................... 40 ns

F. Minimum Setup Clock Rising Edge to Strobe ........ 50 ns

G. Minimum Strobe Pulse Width ............................... 150 ns

H. Minimum Setup Sleep to Strobe Falling ................. 50

µs

Layout. The printed wiring board should use a heavy ground

plane. For optimum electrical and thermal performance, the

driver should be soldered directly onto the board. The ground

side of R

the driver. This path should be as short as physically possible

and should not have any other components connected to it. The

load supply pin, V

capacitor (>47

µF is recommended) placed as close to the driver

as is possible.