L497D1 Datasheet L497D1 | P7-P9

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Figure 2 : SRC : I

coil

Failure and Time Dependence of Active Region.

Figure 3 : Permanent Conduction Protection.

: Input signal

: Coil current

: Voltage on capacitor C

SRC.

: Percentage of imposed desaturation time.

PERMANENT CONDUCTION PROTECTION

(fig. 3)

The permanent conduction protection circuit moni-

tors the input period, charging CP with a costant cur-

rent when the sensor signal is high and discharging

it when the sensor signal is low. If the input remains

high for a time longer than T

the voltage across C

reaches an internally fixed value forcing the slow de-

crease of coil current to zero. A slow decrease is

necessary to avoid undesired sparks. When the in-

put signal goes low again C

is swiftly discharged

and the current control loop operates normally.

The delay time T

is given by :

(sec) = 18 C

Where R

is the biasing resistor on pin 12 (in K) and

Cp the delay capacitor at pin 9 (in µF).

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OTHER APPLICATION NOTES

DUMP PROTECTION

Load dump protection must be implemented by an

external zener if this function is necessary. In fig. 4

protects the driver stage, the connection be-

tween pin 6 and 7 protects the output transistor of

pin 6. Moreover DZ

protects both the power supply

input (pin 3) and Hall-effect sensor.

Resistor R

is necessary to limit DZ

current during

load dump.

OVERVOLTAGE LIMITATION

The external darlington collector voltage is sensed

by the voltage divider R

, R

. The voltage limitation

increases rising R

or decreasing R

Due to the active circuit used, an R

series net-

work is mandatory for stability during the high vol-

tage condition.

values depend on the darlington used in the

application.

Moreover the resistor R

is suggested to limit the

overvoltage even when supply voltage is discon-

nected during the high voltage condition.

REVERSE BATTERY PROTECTION

Due to the presence of external impedance at pin 6,

3, 16, 15 L497 is protected against reverse battery

voltage.

NEGATIVE SPIKE PROTECTION

If correct operation is requested also during short

negative spikes, the diode D

and capacitor C

must

be used.

Figure 4 : Application Circuit.

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DIP16

DIM.

mm inch

MIN. TYP. MAX. MIN. TYP. MAX.

a1 0.51 0.020

B 0.77 1.65 0.030 0.065

b 0.5 0.020

b1 0.25 0.010

D 20 0.787

E 8.5 0.335

e 2.54 0.100

e3 17.78 0.700

F 7.1 0.280

I 5.1 0.201

L 3.3 0.130

Z 1.27 0.050

OUTLINE AND

MECHANICAL DATA

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P1-P3 P4-P6 P7-P9 P10-P11

L497D1

Mfr. #:

Buy L497D1

Manufacturer:

STMicroelectronics

Description:

IC CTRLR HALL EFFECT IGN SOIC-16

Lifecycle:

New from this manufacturer.

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L497D1