01-Jun-2002 Rev. A

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Any changing of specification will not be informed individual

Elektronische Bauelemente

SQ2181

CMOS Positive

Voltage Regulator

Ordering Information(contd.)

Detailed Description

The SQ2181 of COMS regulators contain a PMOS pass transistor,voltage reference, error amplifier,over-current protection and

thermal shutdown. The P-channel pass transistor receives data from the error amplifier,over-current shutdown,and thermal protection

circuits. During normal operation, the error amplifier compares the output voltage to a precision reference.Over-current and Thermal shutdown

circuits become active when the junction temperature exceeds150 C,or the current exceeds 150mA.During thermal shutdown, the

output voltage remains low. Normal operation is restored when the junction temperature drops below 120 C.

The SQ2181 switches from voltage mode to current mode when the load exceeds the rated output current.This prevents over-stress.

The SQ2181 also incorporates

o

o

current fold-back to reduce power dissipation when the output is short circuited.This feature becomes active

when the output drops below 0.8 volts, and reduces the current flow by 65%. Full current is restored when the voltage exceeds 0.8 volts.

The SQ2181 is stable with an output capacitance to ground of 0.22uF or greater. Ceramic capacitors have the lowest ESR, and will offer

the best AC performance. Conversely, Aluminum Elertrolytic capacitors exhibit the highest ESR, resulting in the poorest AC response.

A second capacitor is recommended between the input and ground to stabilize Vin. The input capacitor should be at least 0.1uF to

capacitors should be placed in close proximity to the pins. A "Quiet"

is desirable . The can be achieved with a "Star" connection.

Shutdown

When actively, pulled low, the PMOS pass transistor shuts off, and all internal circuits are powered down. In the state, the quiescent

current is less than 1uA. This pin behaves much like an electronic switch.

have a beneficial effect. A large capacitor improves the AC ripple rejection, but also makes the output come up slowly. This "Soft"

All

turn-on is desirable in some applications to limit turn-on surges.

ground termination

External Capacitors

Characteristics Curve

SQ2181-15

Part Number

Marking

Output Voltage

Part Number

Marking

Output Voltage

SQ2181-20

SQ2181-27

SQ2181-2H

SQ2181-32

1L152

1.5V

2.0V

2.7V

2.85V

3.2V

SQ2181-18

SQ2181-25

SQ2181-28

SQ2181-30

SQ2181-33

1.8V

2.5V

2.8V

3.0V

3.3V

XXXX

1L202

XXXX

1L272

XXXX

1L2H2

XXXX

1L322

XXXX

1L182

XXXX

1L252

XXXX

1L282

XXXX

1L302

XXXX

1L332

XXXX