3195

PROTECTED, HIGH-TEMP.,

ACTIVE PULL-DOWN

HALL-EFFECT LATCH

115 Northeast Cutoff, Box 15036

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

6

INTERNAL PROTECTIVE FEATURES

ISO

Pulse No.

Test

1

Inductive Turn Off (Negative)

2

Inductive Turn Off (Positive)

3a

Capacitive/Inductive Coupling (Neg)

3b

Capacitive/Inductive Coupling (Pos)

4

Reverse Battery

5

Load Dump (ISO)

(DIN)

6

Ignition Coil Disconnect

EXTERNAL PROTECTION REQ’D

7

Field Decay (Negative)

output transistor will be thermally stressed.

Current through the active pull-down is

limited to between 8 mA and 25 mA.

Overvoltage. The device protects itself

against high-voltage transients by shutting

OFF the output source driver and all supply-

referenced active components, reducing the

supply current, and minimizing device

power dissipation. Overvoltage shutdown

can occur anywhere between 28 V and

55 V and device operation above 28 V

cannot be recommended. The device will

continue to operate, with increased power

dissipation, for supply voltages above the

internal clamp voltage but below the over-

voltage shutdown. Under a sustained

overvoltage, the device may be required to

dissipate an increased amount of power

thermally stressed (see above).

Output Voltage. The output is

clamped with an on-chip Zener diode to

prevent supply overvoltage faults from

appearing at the output when the field is

When any fault condition is removed,

the device returns to normal operating

mode.

0

12 V

V

S

t

r

t

d

0.9 V

0.1 V

S

S

Power supply voltage transients, or device output short circuits, may

be caused by faulty connectors, crimped wiring harnesses, or service

errors. To prevent catastrophic failure, internal protection against

overvoltage, reverse voltage, output overloads have been incorporated

to meet the automotive 12 volt system protection requirements of ISO

DP7637/1 and DIN 40839-1. A series-blocking diode or current-limiting

resistor is required in order to survive pulse number six.

Output Overloads. Current through the output source transistor is

sensed with a low-value on-chip aluminum resistor. The voltage drop

across this resistor is fed back to control the base drive of the output

stage. This feedback prevents the output transistor from exceeding its

maximum current density rating by limiting the output current to between

-26 mA and -70 mA. Under short-circuit conditions, the device will