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PIN FUNCTIONS (refer to fig. 3 for DIP16 package)
N
°
Name
Function
1
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)
2
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%.
3
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
resistor at
pin 7. For the optimized operation of the device, C2 = C5.
4
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
resistor at pin 7.
5
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.
6
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.
1.
7
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
.
8
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
F capacitor and 100K resistor R11 at pin 7 the typical delay is 1s.
9
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
s.
10
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
R1
+ R2
RS
R2
11
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
R8
+ R9
R9
+ 5 104 R8
(the resistor R9 value must be higher than 4K
).
12
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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