3958

DMOS FULL-BRIDGE

PWM MOTOR DRIVER

115 Northeast Cutoff, Box 15036

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

6

FUNCTIONAL DESCRIPTION (continued)

Serial Port Write Timing

DATA

CLOCK

Dwg. WP-038

STROBE

A

F

B

G

C

D

E

D19

D0

D18

D15 Phase Logic. Bit D15, in conjunction with

PHASE, determines if the device is operating in the

forward (PHASE

≠ D15) or reverse (PHASE = D15) state.

PHASE D15

State

0

0

Reverse

Low

High

1

0

ForwardHigh

Low

0

1

ForwardHigh

Low

1

1

Reverse

Low

High

D16) or by 10 (RANGE = D16).

RANGE

D16

Divider

00

÷10

10

÷5

01

÷5

11

÷10

D17 Internal PWM Mode. Bit D17, in conjunction with

MODE, selects slow (MODE

≠ D17) or mixed (MODE =

D17) current decay.

MODE D17

Current-Decay Mode

0

0

Mixed

1

0

Slow

0

1

Slow

1

1

Mixed

D18 Test Mode. Bit D18 low (default) operates the

device in normal mode. D18 is only used for testing

purposes. The user should never change this bit.

D19 Sleep Mode. Bit D19 selects a Sleep mode to

minimize power consumption when not in use. This

disables much of the internal circuitry including the

regulator and charge pump. On power up the serial port is

initialized to all 0s. Bit D19 should be programmed high

for 1 ms before attempting to enable any output driver.

D19

Sleep Mode

0

Sleep

1

Normal

Serial Port Write Timing Operation. Data is clocked

into the shift register on the rising edge of the CLOCK

signal. Normally STROBE will be held high, only

brought low to initiate a write cycle. Refer to diagram

below and these specifications for the minimum timing

requirements.

A. DATA setup time ......................................... 15 ns

B. DATA hold time ........................................... 10 ns

C. Setup STROBE to CLOCK rising edge ....... 50 ns

D. CLOCK high pulse width ............................ 50 ns

E. CLOCK low pulse width .............................. 50 ns

F. Setup CLOCK rising edge to STROBE ....... 50 ns

G. STROBE pulse width ................................... 50 ns