General Description

The MAX16821A/MAX16821B/MAX16821C pulse-

width-modulation (PWM) LED driver controllers provide

high output-current capability in a compact package

with a minimum number of external components. The

MAX16821A/MAX16821B/MAX16821C are suitable for

use in synchronous and nonsynchronous step-down

(buck), boost, buck-boost, SEPIC, and Cuk LED drivers. A

logic input (MODE) allows the devices to switch between

synchronous buck and boost modes of operation. These

devices are the first high-power drivers designed specifi-

cally to accommodate common-anode HBLEDs.

The ICs offer average current-mode control that enable

the use of MOSFETs with optimal charge and on-resis-

tance figure of merit, thus minimizing the need for

external heatsinking even when delivering up to 30A of

LED current.

The differential sensing scheme provides accurate con-

trol of the LED current. The ICs operate from a 4.75V to

5.5V supply range with the internal regulator disabled

7V to 28V input supply voltage with the internal regula-

tor enabled.

The MAX16821A/MAX16821B/MAX16821C feature a

clock output with 180° phase delay to control a second

out-of-phase LED driver to reduce input and output fil-

ter capacitor size and to minimize ripple currents. The

wide switching frequency range (125kHz to 1.5MHz)

allows the use of small inductors and capacitors.

Additional features include programmable overvoltage

protection and an output enable function.

Applications

Front Projectors/Rear Projection TVs

Portable and Pocket Projectors

Automotive Exterior Lighting

LCD TVs and Display Backlight

Automotive Emergency Lighting and Signage

Features

♦ Up to 30A Output Current

♦ True-Differential Remote Output Sensing

♦ Average Current-Mode Control

♦ 4.75V to 5.5V or 7V to 28V Input-Voltage Range

♦ 0.1V/0.03V LED Current-Sense Options Maximize

Efficiency (MAX16821B/MAX16821C)

♦ Thermal Shutdown

♦ Nonlatching Output Overvoltage Protection

♦ Low-Side Buck Mode with or without

Synchronous Rectification

♦ High-Side Buck and Low-Side Boost Mode with or

without Synchronous Rectification

♦ 125kHz to 1.5MHz Programmable/Synchronizable

Switching Frequency

♦ Integrated 4A Gate Drivers

♦ Clock Output for 180° Out-of-Phase Operation for

Second Driver

♦ -40°C to +125°C Operating Temperature Range

High-Power Synchronous HBLED

Drivers with Rapid Current Pulsing

________________________________________________________________

Maxim Integrated Products

1

Q1

HIGH-FREQUENCY

PULSE TRAIN

C2

Q3

L1

R1

C1

7V TO 28V

.

CSP

DL

DH

NOTE: MAXIM PATENT-PENDING TOPOLOGY

PGND

EN

IN

I.C.

OVI

CLP

Q2

MAX16821

Simplified Diagram

19-0881; Rev 0; 7/07

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Typical Operating Circuit and Selector Guide appear at end

of data sheet.

Ordering Information

+

Denotes a lead-free package.

*

EP = Exposed pad.

PART

TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MAX16821AATI+ -40°C to +125°C

28 TQFN-EP*

T2855-8

MAX16821BATI+ -40°C to +125°C

28 TQFN-EP*

T2855-8

MAX16821CATI+ -40°C to +125°C

28 TQFN-EP*

T2855-8