5.2A

+

-

FB

COMP

CONTROL

LOGIC

EN

CURRENT LIMIT

OVERVOLTAGE

UNDERVOLTAGE

ERROR AMP

PWM COMPARATOR

SS/TRK

PGOOD

+

-

+5.5V

REGULATOR

VCC

BOOT

VCC

THERMAL

PROTECTION

GND

SW

VIN

CURRENT SENSE

VCC

1.25V

BOOT

BOOT

UVLO

4.25V

AGND

+

740 mV

880 mV

PG-L

PG-L

VREF

+

-

800 mV

+

-

+

2 PA

DISCHARGE

DISCHARGE

SLOPE COMP

4.5 PA

+

-

-2.8A

NEGATIVE

CURRENT LIMIT

+2.7V

REGULATOR

2.7V

+

-

+

-

+

-

+

-

500 kHz

OSCILLATOR

INTERNAL

+5.5V

REGULATOR

VCC_INT

ENABLE_INT

ENABLE_INT

2.7V

VCC_INT

LM20323

SNVS557B – MAY 2008 – REVISED JANUARY 2009

www.ti.com

Block Diagram

Operation Description

GENERAL

The LM20323 switching regulator features all of the functions necessary to implement an efficient buck regulator

using a minimum number of external components. This easy to use regulator features two integrated switches

and is capable of supplying up to 3A of continuous output current. The regulator utilizes peak current mode

control with nonlinear slope compensation to optimize stability and transient response over the entire output

voltage range. Peak current mode control also provides inherent line feed-forward, cycle-by-cycle current limiting

and easy loop compensation. The 500kHz switching frequency minimizes the inductor size while keeping

10

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