vb325 STMicroelectronics, vb325 Datasheet - Page 4

• Manufacturer Part Number: vb325
• Description: High Voltage Ignition Coil Driver Power I.c.
• Manufacturer: STMicroelectronics

VB325SP
ELECTRICAL CHARACTERISTICS (continued)
PRINCIPLE OF OPERATION
The VB325SP is mainly intended as a high voltage
power switch device driven by a logic level input
and interfaces directly to a high energy electronic
ignition coil.
The input V
power signal generated by an external controller
that determinesboth dwell time and ignition point.
During Vin high ( 4V) the VB325SP increases
current in the coil to the desired, internally set
current level.
After reaching this level, the coil current remains
constant until the ignition point, that corresponds
to the transition of Vin from high to low (typ. 1.9V
threshold).
During the coil current switch-off, the primary
voltage HV
4/9
Figure 1: Flag current Vs. temperature
Symbol
V
V
BD(off)
BD(on)
I
I
EH
EL
C
High Level Enable Current
Low Level Enable Current
Base Darlington Voltage Off V
Base Darlington Voltage On V
IN
is clamped at an internally set value
of the VB325SP is fed from a low
Parameter
V
V
E
E
E
IN
=5V
<0.4V
=V
=V
EH
INH
; V
Test Conditions
E
=V
EL
V
to desaturation, coil current limiting phase, must
have the ability to accomodate an overvoltage.
A maximum overshoot of 20V is allowed.
FEEDBACK
When the collector current exceeds 4.5A, the
feedback signal is turned high and it remains so,
until the input voltage is turned-off.
OVERVOLTAGE
The VB325SP can withstand the following
transients of the battery line:
-100V/2msec(R
+100V/0.2msec (R
+50V/400msec (R
Figure 2: Single pulse avalanche energy capability
; I
cl
C
, typically 380V. The transition from saturation
=6.5A
700
650
600
550
500
450
400
350
300
250
200
150
100
50
0
0
10
20
i
=10 )
30
i
i
= 4.2 , with V
=10 )
- 200
Tc=150º
Min
40
1.8
Tc=25º
C
L (mH)
50
60
Typ
70
IN
= 3V)
80
Max
500
1
90
100
Unit
V
V
A
A
110