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3976 Dual Protected PWM Motor Driver

APPLICATION NOTES

operation diagnostic circuitry will look for a minimum

source current level after a bridge is signalled on.

Additionally, the diode flyback is monitored on the proper

output. The logic will signal a fault and disable the outputs if

it determines that the current is below the minimum level

AND no flyback is occurring. If the inductive load is too

large, the current would take too long to reach the minimal

level and a false open load would be reported. It is

recommended that the inductive load be less than 38mH.

greater than 1.1A is detected. To prevent false overcurrent

events due to reverse recovery spikes of the clamp diodes,

the current monitor is blanked for 5us after a high side is

signalled to turn on. If an additional input command follows

after the initial fault, the selected pair of drivers will pulse on

for the 5us blanking duration. The short circuit fault will

remember the input state where the fault occurred and will

wait for that particular logic state after the short has been

removed before normal operation is allowed to resume.

when the junction temperature reaches 170°C typically. It is

intended only to protect the device from failures due to

excessive junction temperatures and has a hysteresis of

approximately 15°C.

ground plane. For optimum electrical and thermal

performance, the driver should be soldered directly onto the

an electrolytic capacitor (> 47 µF is recommended) placed as

close to the device as possible.

Terminal List

Pin Name

Pin Description

24 Lead SOIC

16 Lead DIP

Motor Supply Voltage

1

1

ENABLE1

Control Logic – Bridge 1

2

2

PHASE1

Control Logic – Bridge 1

3

3

GROUND

Power Ground Return

18,19,6,7

4,5,12,13

OUT1A

Bridge 1 Output

9

6

FAULT1

Diagnostic Output

11

7

OUT1B

Bridge 1 Output

12

8

OUT2B

Bridge 2 Output

13

9

FAULT2

Diagnostic Output

14

10

OUT2A

Bridge 2 Output

16

11

PHASE2

Control Logic – Bridge 2

22

14

ENABLE2

Control Logic – Bridge 2

23

15

Logic Supply

24

16

NC

No Connect

3,4,5,8,15,17,20,21