G9131 데이터 시트보기 (PDF) - Global Mixed-mode Technology Inc

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G9131

300mA Low-Dropout Linear Regulators

Global Mixed-mode Technology Inc 

Global Mixed-mode Technology Inc.

Pin Description

G9131

NAME

IN

GND

OUT

FUNCTION

Regulator Input. Supply voltage can range from VIN(min) to +5.5V. Bypass with 1µF to GND.

This is ground pin.

Regulator Output. Sources up to 300mA. Bypass with a 1µF, ＜0.2Ω typical ESR capacitor to GND.

Detailed Description

The block diagram of the G9131 is shown in Figure 1.

It consists of an error amplifier, 1.25V bandgap refer-

ence, PMOS output transistor, internal feedback volt-

age divider, over current protection circuit, and over

temperature protection circuit.

Over Current Protection

The G9131 use a current sense-resistor to monitor the

output current. A portion of the PMOS output transistor’s

current is mirrored to a resistor such that the voltage

across this resistor is proportional to the output current.

Once the output current exceeds limit threshold, G9131

would be protected with a limited output current. Further

more, when the output is short to ground, the output

current would be folded-back to a less limit.

Over Temperature Protection

To prevent abnormal temperature from occurring, the

G9131 has a built-in temperature monitoring circuit.

When it detects the temperature is above 150°C, the

output transistor is turned off. When the IC is cooled

down to below 135°C, the output is turned on again. In

this way, the G9131 will be protected against abnor-

mal junction temperature during operation.

Operating Region and Power Dissipation

Since the G9131 is a linear regulator, its power dissi-

pation is always given by P = IOUT (VIN - VOUT). The

maximum power dissipation is given by: PD(MAX) = (TJ -

TA)/θJA, Where (TJ - TA) is the temperature difference

the G9131 die and the ambient air. For surface mount

device, heat sinking is accomplished by using the heat

spreading capabilities of the PC board and its copper

traces. θJA is the thermal resistance of the chosen

package to the ambient air. In the case of a SOT-23

package, the thermal resistance is typically 275.5°C/W.

In SOT 89 RθJA is 172.5°C/W.

Ver: 1.6

Dec 22, 2005

TEL: 886-3-5788833

http://www.gmt.com.tw

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