GL2137

Page: 3/5

ISSUED DATE :2006/05/16

REVISED DATE :

Ordering Information ( contd. )

Part Number

Marking

Output Voltage

Part Number

Marking

Output Voltage

GL2137-15

7T152

XXXX

1.5V

GL2137-18

7T182

XXXX

1.8V

GL2137-25

7T252

XXXX

2.5V

GL2137-27

7T272

XXXX

2.7V

GL2137-28

7T282

XXXX

2.8V

GL2137-29

7T292

XXXX

2.9V

GL2137-30

7T302

XXXX

3.0V

GL2137-31

7T312

XXXX

3.1V

GL2137-33

7T332

XXXX

3.3V

GL2137-34

7T342

XXXX

3.4V

GL2137-35

7T352

XXXX

3.5V

GL2137-36

7T362

XXXX

3.6V

GL2137-3.7

7T372

XXXX

3.7V

GL2137-38

7T382

XXXX

3.8V

GL2137-2H

7T2H2

XXXX

2.85V

Detailed Description

The GL2137 series 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 exceeds

150 : , or the current exceeds 750mA. During thermal shutdown, the output voltage remains low. Normal

operation is restored when the junction temperature drops below 120 : .

The GL2137 switches from voltage mode to current mode when the load exceeds the rated output current.

This prevents over-stress. The GL2137 also incorporates current fold-back to reduce power dissipation when

the output is short circuited. This feature becomes active when the output drops below 0.8V and reduces the

current flow by 65%. Full current is restored when the voltage exceeds 0.8V.

External Capacitors

The GL2137 is stable with an output capacitance to ground of 2.2 F or greater. Ceramic capacitors have the

lowest ESR, and will offer the best AC performance. Conversely, Aluminum Electrolytic capacitors exhibit the

highest ESR, resulting in the poorest AC response. Unfortunately, large value ceramic capacitors are

comparatively expensive. One option is to parallel a 0.1 F ceramic capacitor with a 10 F Aluminum Electrolytic.

The benefit is low ESR, high capacitance, and low overall cost.

A second capacitor is recommended between the input and ground to stabilize Vin. The input capacitor should

be at least 0.1 F to have a beneficial effect.

All capacitors should be placed in close proximity to the pins. A “Quiet” ground termination is desirable. This

can be achieved with a “Star” connection.