Control

Logic

Thermal

Shutdown

OSC

RAMP

INT

SS

VREF

0.6V

+

Å

AVIN

EN

SYNC

SS/TRK

FB

COMP

AGND

PGND

PGOOD

SW

PVIN

PWM

Comparator

UVLO

Precision

Enable

UVP

SD

Zero-cross

OVP

PowerBAD

PWM

0.675V

0.54V

PLL

AVIN

AVIN

PVIN

PVIN

OR

OR

OR

+

Å

+

Å

+

Å

+

Å

+

Å

EA

+

Å

+

Å

2.7V

1.35V

0.6V

1.9 A

+

Driver

Driver

LM21215A

www.ti.com

SNOSB87C – MARCH 2011 – REVISED JANUARY 2016

7 Detailed Description

7.1 Overview

The LM21215A synchronous buck regulator features all of the functions necessary to implement an efficient low-

voltage converter using a minimum number of external components. This easy-to-use regulator features two

integrated power MOSFET switches and is capable of supplying up to 15 A of continuous output current.

Synchronous rectification yields high efficiency for low output voltage and high load current applications, whereas

discontinuous conduction mode (DCM) with diode emulation mode (DEM) enables high-efficiency conversion

with light load current conditions.

The regulator utilizes voltage-mode control with trailing-edge PWM modulation to optimize stability and transient

response over the entire input voltage range. The device operates at high switching frequency, allowing the use

of a small inductor yet still achieving high efficiency. The precision internal voltage reference allows output

voltages as low as 0.6 V. Fault protection features include peak and valley current limiting, thermal shutdown,

overvoltage protection, and undervoltage lockout. The device is available in the HTSSOP-20 package featuring

an exposed pad to aid thermal dissipation. The LM21215A is ideal for numerous applications to efficiently step-

down from a 5-V or 3.3-V bus.

7.2 Functional Block Diagram

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