IRU1261

3

Rev. 2.0

09/19/02

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BLOCK DIAGRAM

The control input pin of the regulator. This pin is connected, via a 10

V resistor, to the 5V

supply to provide the base current for the pass transistor of both regulators. This allows

the regulator to have very low dropout voltage which allows one to generate a well regu-

lated 2.5V supply from the 3.3V input. A high frequency, 1

mF capacitor is connected

The output #2 (high current) of the regulator. A minimum of 100

mF capacitor must be

connected from this pin to ground to insure stability.

This pin is connected to ground. It is also the Tab of the package.

The power input pin of the regulator. Typically a large storage capacitor is connected from

this pin to ground to insure that the input voltage does not sag below the minimum drop

out voltage during the load transient response. This pin must always be higher than both

regulate properly.

The output #1 (low current) of the regulator. A minimum of 100

mF capacitor must be

connected from this pin to ground to insure stability.

Figure 2 - Simplified block diagram of the IRU1261.

Gnd

1

2

3

4

5

PIN DESCRIPTIONS

PIN # PIN SYMBOL

PIN DESCRIPTION

Gnd

4

1

3

2

THERMAL

SHUTDOWN

1.20V

+