3974

DMOS DUAL FULL-BRIDGE

PWM MOTOR DRIVER

115 Northeast Cutoff, Box 15036

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

6

FUNCTIONAL DESCRIPTION (continued)

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D14 Enable Logic. This bit, in conjuction with ENABLE,

determines if the output drivers are in the chopped or on state.

ENABLE1

D14

Mode

0

0

Chopped

10

On

01

On

1

1

Chopped

D15 Phase Logic. This bit determines if the device is

operating in the forward or reverse state.

D15

State

OUT

A

OUT

B

0

Reverse

L

H

1

Forward

H

L

D16 G

by 5 or 10.

D16

Divider

0

÷10

1

÷5

D17 Bridge 2 Mode. This bit determines slow or mixed

decay for internal current-control operation.

D17

Decay Mode

0

Mixed

1

Slow

D19 Test Mode. This bit is reserved for testing and should

never be changed by the user. Default (low) operates the

device in normal mode.

Word 1 Bit Assignments

Select Word 1 (D18 = 1)

Bit

Function

D0

Bridge 2 blank time LSB

D1

Bridge 2 blank time MSB

D2

Bridge 2 off-time LSB

D3

Bridge 2 off-time bit 1

D4

Bridge 2 off-time bit 2

D5

Bridge 2 off-time bit 3

D6

Bridge 2 off-time MSB

D7

Bridge 2 fast-decay time bit LSB

D8

Bridge 2 fast-decay time bit 1

D9

Bridge 2 fast-decay time bit 2

D10

Bridge 2 fast-decay time bit MSB

D11

Bridge 2 sync. rect. control

D12

Bridge 2 sync. rect. control

D13

Bridge 2 external PWM mode

D14

Bridge 2 enable

D15

Bridge 2 phase

D16

Bridge 2 reference range select

D17

Bridge 2 internal PWM mode

D18

Word select = 1

D19

Idle mode

D0 - D17. Identical definitions as Word 0, with Word 1

selected. Data is written to Full Bridge 2.

D19 Idle Mode. The device can be placed in a low-power

“idle” mode by writing a “0” to D19. The outputs will be

disabled, the charge pump will be turned off, and the device

will draw a lower load supply currrent. The undervoltage

monitor circuit will remain active. D19 should be programmed

high for 1 ms before attempting to enable any output driver.