VB027(011Y) STMicroelectronics, VB027(011Y) Datasheet - Page 4

• Manufacturer Part Number: VB027(011Y)
• Description: HIGH VOLTAGE IGNITION COIL DRIVER POWER I.C.
• Manufacturer: STMicroelectronics

VB027 / VB027(011Y) / VB027(012Y)
PRINCIPLE OF OPERATION
The
intended as high voltage power switch device driven by a
logic level input and interfaces directly to a high energy
electronic ignition coil.
The
VB027(012Y)
by an external controller that determines both dwell time
and ignition point. During V
VB027(011Y), VB027(012Y)
coil to the desired, internally set current level.
When the collector current exceeds 4.5A, the diagnostic
signal is turned high and it remains so, until the load
current reaches 5.8A (second threshold). At that value,
the diagnostic signal is turned low, and the C forces the
V
primary voltage HV
diodes at an internally set value V
The collector current sensed through the R
thanks to the “Current limiter” block that, as soon as the I
level is reached, forces the darlington (using the “Driver”
block) to limit the current provided.
The transition from saturation to desaturation, coil current
limiting phase, must have the ability to accommodate an
overvoltage. A maximum overshoot of 20V is allowed.
There can be some short period of time in which the
output pin (HV
current
capacitances of the ignition coil. This can cause parasitic
glitches
VB027(011Y), VB027(012Y)
circuit that allows to lock the p-buried layer potential of the
linear stage to the collector power, when the last one is
pulled underground.
FIGURE 1: Application circuit
4/9
1
IN
to the low state. During the coil current switch-off, the
VB027, VB027(011Y), VB027(012Y)
input
due
on
V
IN
C
to
is fed from a low power signal generated
) is pulled below ground by a negative
the
of
C
leakage
is clamped by a series of Zener
the
diagnostic
IN
VB027,
inductances
high ( 4V) the
increases current in the
has a built-in protection
cl
, typically 360V.
output.
VB027(011Y),
sense
and
, is limited
is mainly
VB027,
VB027,
stray
cl
THERMAL BEHAVIOUR
You can see in the block diagram of the
VB027(011Y),
overtemperature protection. The purpose of this circuit is
to shift the current level at which the first diagnostic is
activated down of about 1A.
This information can be managed by the micro that can
take the corrective action in order to reduce the power
dissipation. This block is not an effective protection but
just an overtemperature detection. The shift down of the
first flag level cannot be present for temperatures lower
than 125 C.
As an example of its behavior you can suppose a very
simple motor management system in which the micro
does just a simple arithmetic calculation to decide when to
switch-off the device after the first flag threshold.
EXAMPLE:
I
I
As soon as the temperature rises over the overtemp
threshold, the first diagnostic is shifted down to about
1.5A and, in this example, the switch-off current will be
kx*1.5 / 2.5.
OVERVOLTAGE
The
withstand the following transients of the battery line:
-100V / 2ms (R
+100V / 0.2ms (R
+50V / 400ms (R
C(DIAG1)
switch-off
VB027, VB027(011Y), VB027(012Y)
info after kx ms.
info after x ms (I
i
=10 )
i
=4.2
i
=10 )
VB027(012Y)
C(DIAG1)
with V
IN
=2.5A)
=3V)
a
box
VB027,
called
can