L482 datasheet(3/11 Pages) STMICROELECTRONICS

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PIN FUNCTIONS (refer to fig. 3 for DIP16 package)

Name

Function

CONDUCTION TIME

SIGNAL

A low level on this output signal indicates when the external darlington is in

the ON condition i.e. when the current flows through the coil (ton in fig.1)

HALL-EFFECT INPUT

Hall-effect Pickup Input. A high level on this pin enables the current driving

into the coil. The effective coil charge will be a function of the dwell control

logic. A High to Low transition from the Hall-effect pickup is the signal for

ignition actuation. The input signal, supplied by the open collector output

stage of the Hall-effect sensor, has a duty cycle typically about 70%.

DWELL CONTROL

The average voltage on the capacitor C2 connected between this pin and

ground depends on the motor speed and the voltage supply. The

comparison between VC2 and VC5 voltages determines the timing for the

dwell control. The recommended value is 100nF using a 100K

Ω resistor at

pin 7. For the optimized operation of the device, C2 = C5.

DWELL CONTROL TIMER

The capacitor C5 connected between this pin and ground is charged when

the Hall-effect output is high and is discharged at the High to Low transition

of the Hall-effect signal. The recommended value is 100nF using a 100K

Ω

resistor at pin 7.

HALL SENSOR SUPPLY

This pin can be used to project the Hall-effect pickup against the voltage

transients, The resistor Ra limits the current into the internal zener.

DESATURATION TIME

SIGNAL

Open Collector Output Signal. This output is high when the external

darlington is in desaturation condition (current limitation), see td pulse in fig.

REFERENCE VOLTAGE

A resistor R11 connected between this pin and ground sets the internal

current used to drive the external capacitors of the dwell control (C2 and

C5) and permanent conduction protection (C1). The recommended value is

100K

Ω.

PERMANENT CONDUCT.

PROTECTION TIMER

A capacitor C1 connected between this pin and ground determines the

intervention delay of the permanent conduction protection, tpc of the figure 2.

With a 1

µF capacitor and 100KΩ resistor R11 at pin 7 the typical delay is 1s.

PERMANENT CONDUCT.

RESET OUTPUT

(no available in

Micropackage) (*)

A low pulse on this output detects the intervention of the permanent

conduction protection, as shown in figure 2. Typically the duration of the

time tr is more than 100

µs.

CURRENT SENSING

INPUT (*)

Connection for Coil Current Limitation. The current is measured on the

sense resistor RS and divided on R1/R2. The current limitation value is

given by :

ISENS

= VSENS

+ R2

⋅ R2

DUMP PROTECTION

(*)

The device is protected against the load dump. In load dump condition an

internal circuit,

based on a zener diode and a darlington transistor,

switches off the external darlington and short circuits the supply.

By means of the external divider R8/R9 the protection threshold can be

changed and is given as first approximation by:

VDth

= 8.5 ⋅ 



+ R9







+ 5 ⋅ 10−4 ⋅ R8

(the resistor R9 value must be higher than 4K

Ω).

POWER SUPPLY (*)

Supply Voltage Input. A 7V (typ) zener is present at the input. The external

resistor R7 limits the current through the Zener for high supply voltages.

L482

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