2000 Feb 01

4

Philips Semiconductors

Preliminary specification

Very low dropout voltage/quiescent current

5 V regulator with overvoltage switch off

TDA3668AT

FUNCTIONAL DESCRIPTION

The TDA3668AT is a fixed 5 V regulator which can deliver

output currents up to 100 mA. The regulator is available in

an SO8 package. The regulator is intended for portable,

mains, telephone and automotive applications.

To increase the lifetime of batteries, a specially built-in

clamp circuit keeps the quiescent current of this regulator

very low, also in dropout and full load conditions.

The regulator remains operational down to very low supply

voltages and at lower voltages it switches off.

A temperature protection circuit is included, which

switches off the regulator output at a junction temperature

above 150

°C.

A new output circuit guarantees the stability of the

regulator for a capacitor output circuit with an ESR up to

38

Ω. This is very attractive as the ESR of an electrolytic

capacitor increases strongly at low temperatures

(no expensive tantalum capacitor is required).

A load dump circuit (see Fig.3) and an overvoltage

protection circuit is built-in which will switch off the IC

above 28 V (typical value).

handbook, halfpage

MGS590

tr

VP

(V)

tf

50

14.4

t (ms)

Fig.3 Load dump pulse.

LIMITING VALUES

In accordance with the Absolute Maximum Rating System (IEC 134).

THERMAL CHARACTERISTICS

QUALITY SPECIFICATION

In accordance with

“SNW-FQ-611E”.

SYMBOL

PARAMETER

CONDITIONS

MIN.

MAX.

UNIT

supply voltage

operating

−

24

V

load dump

−

50

V

reverse polarity supply voltage

non-operating

−−25

V

total power dissipation

temperature of PCB ground

plane is 25

°C

−

4.1

W

storage temperature

non-operating

−55

+150

°C

ambient temperature

−40

+125

°C

junction temperature

operating

−40

+150

°C

SYMBOL

PARAMETER

CONDITIONS

VALUE

UNIT

thermal resistance from junction to ambient

in free air; soldered

125

K/W

thermal resistance from junction to case

to centre pins; soldered

30

K/W