RT9078

3

DS9078-08 June 2017

www.richtek.com

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Copyright 2017 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

Functional Block Diagram

Operation

Basic operation

The RT9078 is a low quiescent current linear regulator

designed especially for low external components system.

The input voltage range is from 1.2V to 5.5V.

The minimum required output capacitance for stable

operation is 1

μF capacitance after consideration of the

temperature and voltage coefficient of the capacitor.

Output Transistor

The RT9078 builds in a P-MOSFET output transistor which

provides a low switch-on resistance for low dropout voltage

applications.

Error Amplifier

The ErrorAmplifier compares the internal reference voltage

with the output feedback voltage from the internal divider,

and controls the Gate voltage of P-MOSFET to support

good line regulation and load regulation at output voltage.

Enable

The RT9078 delivers the output power when it is set to

enable state. When it works in disable state, there is no

output power and the operation quiescent current is almost

zero.

Current Limit Protection

The RT9078 provides current limit function to prevent the

device from damages during over-load or shorted-circuit

condition. This current is detected by an internal sensing

transistor.

Over Temperature Protection

The over temperature protection function will turn off the

P-MOSFET when the junction temperature exceeds 150

°C

(typ.), and the output current exceeds 80mA. Once the

junction temperature cools down by approximately 20

°C,

the regulator will automatically resume operation.

VIN

GND

EN

VOUT

R1

R2

Current/Thermal

Sense

Bandgap

Reference

SNS

(without sense

function)

(with sense

function)

EN