4

Circuit Description

Typical Application Circuits

0.1

mF

1

2

3

5

CS8240

GE194

0.1

mF

1

2

3

5

CS8240

0V

5V

Solenoid Driver

CS8240

LOAD

15k

W

Lamp Driver

Controlled High Side Switch

Input Stage

The input stage is a self biased band gap based circuit with a

positive going trip point of 1.45V (typ) and a negative going

trip point of 1.20V (typ) (250mV of hysteresis). When the input

voltage is below the positive trip point, the quiescent current

of the supply voltage line is less than 1µA, (typ). When the

input voltage exceeds the positive trip point (1.45V, typ), the

input stage Òwakes upÓ the rest of the CS8240 circuitry and

turns on the output stage.

Output Stage

The output stage is built around a high current PNP output

transistor. A control amplifier monitors the saturation voltage

of the output PNP and maintains a balance of low saturation

voltage and minimum base drive to the PNP for the given out-

put current. The base drive of the PNP is the dominant com-

ponent of the quiescent current of the CS8240 and is depen-

dent on the level of output current.

Short circuit protection (1.1A, typ) is also incorporated in the

output stage.

Protection Circuitry

In addition to the short circuit protection mentioned above,

the CS8240 also incorporates a thermal shutdown circuit

(165¡C, typ) and a high voltage shutdown circuit (33V, typ),

both of which cut off the drive to the PNP output transistor

when excessive current is drawn. Inherent in the design of the

CS8240 is transient protection to +60V and -50V on the supply

line. The CS8240 is ESD protected in excess of 2kV (Human

Body Model).