TDA3672 datasheet(7/16 Pages) PHILIPS

7 / 16 page

2000 Apr 26

Philips Semiconductors

Preliminary speciﬁcation

Very low dropout voltage/quiescent current

3.0 V voltage regulator with enable

TDA3672

EXAMPLE 1

The regulator is stabilized with an electrolytic capacitor of

µF (ESR = 0.5 Ω). At Tamb = −40 °C, the capacitor

value is decreased to 22

µF and the ESR is increased

to 3.5

Ω. The regulator will remain stable at a temperature

of Tamb = −40 °C.

EXAMPLE 2

The regulator is stabilized with an electrolytic capacitor of

µF (ESR = 3.3 Ω). At Tamb = −40 °C, the capacitor

value is decreased to 3

µF and the ESR is increased

to 20

Ω. The regulator will remain stable at a temperature

of Tamb = −40 °C.

EXAMPLE 3

The regulator is stabilized with a 100 nF MKT capacitor

connected to the output. Full stability is guaranteed when

the output current is larger then 200

µA.

Because the thermal influence on this capacitor value is

almost zero, the regulator will remain stable at a

temperature of Tamb = −40 °C.

EXAMPLE 4

The regulator is stabilized with a 100 nF capacitor in

parallel with a electrolytic capacitor of 10

µF connected to

the output.

The regulator is now stable under all conditions and

independent of:

• The ESR of the electrolytic capacitor

• The value of the electrolytic capacitor

• The output current.

Application circuits

The maximum output current of the regulator equals:

When Tamb =21 °C and VP = 14 V the maximum output

current equals 117 mA.

For successful operation of the IC (maximum output

current capability) special attention has to be given to the

copper area required as heatsink (connected to all

GND pins), the thermal capacity of the heatsink and its

ability to transfer heat to the external environment.

It is possible to reduce the total thermal resistance from

120 to 50 K/W.

Application circuit with backup function

Sometimes a backup function is needed to supply, for

example, a microcontroller for a short period of time when

the supply voltage spikes to 0 V (or even

−1 V).

This function can be easily built with the TDA3672 by using

a large output capacitor. When the supply voltage is 0 V

(or

−1 V), only a small current will flow into pin REG from

this output capacitor (a few

µA).

The application circuit is given in Fig.6.

REG max

()

150

amb

–

th j

–

()

REG

–

()

-----------------------------------------------------------

150

amb

–

100

3.0

–

()

------------------------------------------ mA

()

ndbook, halfpage

MBL124

2, 3, 6, 7

VI(EN)

TDA3672

µF

VREG = 3.0 V

Fig.6 Application circuit with backup function.

VI(EN) =5V.

C1 is optional (to minimize supply noise only).

≤ 4700 µF.

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