VB325 datasheet(4/9 Pages) STMICROELECTRONICS

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VB325SP

ELECTRICAL CHARACTERISTICS (continued)

Symbol

Parameter

Test Conditions

Min

Typ

Max

Unit

IEH

High Level Enable Current

VE=5V

500

µA

IEL

Low Level Enable Current

VE<0.4V

- 200

µA

VBD(off)

Base Darlington Voltage Off

VE=VEH

VBD(on)

Base Darlington Voltage On

VIN=VINH; VE=VEL; IC=6.5A

1.8

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 VIN of the VB325SP is fed from a low

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 HVC is clamped at an internally set value

Vcl, typically 380V. The transition from saturation

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(Ri =10 Ω)

+100V/0.2msec (Ri =10 Ω)

+50V/400msec (Ri = 4.2 Ω, with VIN= 3V)

Figure 1: Flag current Vs. temperature

Figure 2: Single pulse avalanche energy capability

100

150

200

250

300

350

400

450

500

550

600

650

700

1020

304050

607080

100

110

L (mH)

Tc=25º

Tc=150º

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