VB029012Y Просмотр технического описания (PDF) - STMicroelectronics

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VB029012Y

HIGH VOLTAGE IGNITION COIL DRIVER POWER I.C.

STMicroelectronics 

VB029 / VB029SP / VB029(011Y) / VB029(012Y)

PRINCIPLE OF OPERATION

The VB029, VB029SP, VB029(011Y)

VB029(012Y) are mainly intended as high voltage

power switch device driven by a logic level input and

interfaces directly to a high energy electronic ignition coil.

The input VIN of the VB029, VB029SP, VB029(011Y)

VB029(012Y) are fed from a low power signal

generated by an external controller that determines both

dwell time and ignition point. During VIN high (≥4V) the

VB029, VB029SP, VB029(011Y) VB029(012Y)

increase current in the 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 µC forces the

VIN to the low state. During the coil current switch-off, the

primary voltage HVC is clamped by a series of Zener

diodes at an internally set value Vcl, typically 360V.

The collector current sensed through the Rsense, is limited

thanks to the “Current limiter” block that, as soon as the Icl

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 (HVC) is pulled below ground by a negative

current due to leakage inductances and stray

capacitances of the ignition coil. This can cause parasitic

glitches on the diagnostic output. VB029, VB029SP,

VB029(011Y) VB029(012Y) have a built-in protection

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

THERMAL BEHAVIOUR

You can see in the block diagram of the VB029,

VB029SP, VB029(011Y) VB029(012Y) a box called

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:

IC(DIAG1) info after x ms (IC(DIAG1)=2.5A)

Iswitch-off info after kx ms.

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 VB029, VB029SP, VB029(011Y)

VB029(012Y) can withstand the following transients of

the battery line:

-100V / 2ms (Ri=10Ω)

+100V / 0.2ms (Ri=10Ω)

+50V / 400ms (Ri=4.2 Ω, with VIN=3V)

4/10

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