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EVALUATION KIT AVAILABLE

MAX16821A/MAX16821B/

MAX16821C

High-Power Synchronous HBLED

Drivers with Rapid Current Pulsing

General Description

The MAX16821A, MAX16821B, and 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–MAX16821C are suitable for use in synchro-

nous 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 specifically to accommodate

common-anode HB LEDs.

The ICs offer average current-mode control that enable

the use of MOSFETs with optimal charge and on-

resistance 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 control

of the LED current. The ICs operate from a 4.75V to 5.5V

supply range with the internal regulator disabled (V

CC

connected to IN). These devices operate from a 7V to 28V

input supply voltage with the internal regulator enabled.

The MAX16821A–MAX16821C feature a clock output

with 180° phase delay to control a second out-of-phase

LED driver to reduce input and output filter capacitor size

and to minimize ripple currents. The wide switching fre-

quency range (125kHz to 1.5MHz) allows the use of small

inductors and capacitors.

Additional features include programmable overvoltage

protection and an output enable function.

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

PART

TEMP RANGE

-40°C to +125°C

PIN-PACKAGE

28 TQFN-EP*

Ordering Information

MAX16821AATI+

MAX16821BATI+

MAX16821CATI+

+Denotes lead(Pb)-free/RoHS-compliant package.

*EP = Exposed pad.

Simplified Diagram

7V TO 28V

C1

L1

V

LED

Applications

●

Front Projectors/Rear-Projection TVs

●

Portable and Pocket Projectors

●

LCD TVs and Display Backlight

EN

I.C.

IN

DH

Q1

MAX16821

DL

OVI

CSP

PGND

Q2

C2

Q3

R1

Typical Operating Circuit

and

Selector Guide

appears at

end of data sheet.

CLP

HIGH-FREQUENCY

PULSE TRAIN

19-0881; Rev 4; 4/18

MAX16821A/MAX16821B/

MAX16821C

Absolute Maximum Ratings

IN to SGND ...........................................................-0.3V to +30V

BST to SGND ........................................................-0.3V to +35V

BST to LX ................................................................-0.3V to +6V

DH to LX .......................................-0.3V to (VBST - VLX) + 0.3V

DL to PGND .............................................-0.3V to (VDD + 0.3V)

V

CC

to SGND ..........................................................-0.3V to +6V

V

CC

, V

DD

to PGND .................................................-0.3V to +6V

SGND to PGND....................................................-0.3V to +0.3V

V

CC

Current .....................................................................300mA

High-Power Synchronous HBLED

Drivers with Rapid Current Pulsing

All Other Pins to SGND ............................ -0.3V to (V

CC

+ 0.3V)

Continuous Power Dissipation (T

A

= +70°C)

28-Pin TQFN 5mm x 5mm (derate 34.5mW/°C

above +70°C) ...........................................................2758mW

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

Junction Temperature ......................................................+150°C

Storage Temperature Range ............................ -65°C to +150°C

Lead Temperature (soldering, 10s) ................................. +300°C

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these

or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect

device reliability.

Electrical Characteristics

PARAMETER

Input-Voltage Range

Quiescent Supply Current

LED CURRENT REGULATOR

(V

CC

= 5V, V

DD

= V

CC

, T

A

= T

J

= -40°C to +125°C, unless otherwise noted. Typical values are at T

A

= +25°C.) (Note 1)

SYMBOL

V

IN

I

Q

CONDITIONS

Internal LDO on

Internal LDO off (V

CC

connected to V

IN

)

V

EN

= V

CC

or SGND, no switching

V

IN

= V

CC

= 4.75V to 5.5V, f

SW

= 500kHz

(MAX16821A)

V

IN

= 7V to 28V, f

SW

= 500kHz

(MAX16821A)

Differential Set Value

(V

SENSE

+ to V

SENSE

-)

(Note 2)

V

IN

= V

CC

= 4.75V to 5.5V,

f

SW

= 500kHz (MAX16821B)

V

IN

= 7V to 28V, f

SW

= 500kHz

(MAX16821B)

V

IN

= V

CC

= 4.75V to 5.5V,

f

SW

= 500kHz (MAX16821C)

V

IN

= 7V to 28V, f

SW

= 500kHz

(MAX16821C)

Soft-Start Time

STARTUP/INTERNAL REGULATOR

V

CC

Undervoltage Lockout

(UVLO)

UVLO Hysteresis

V

CC

Output Voltage

MOSFET DRIVER

Output Driver Impedance

Output Driver Source/Sink

Current

Nonoverlap Time

I

DH

, I

DL

t

NO

C

DH/DL

= 5nF

UVLO

V

CC

rising

V

CC

falling

V

IN

= 7V to 28V, I

SOURCE

= 0 to 60mA

Low or high output, I

SOURCE/SINK

= 20mA

4.85

4.1

4.3

200

5.10

1.1

4

35

5.30

3

4.5

V

mV

V

Ω

A

ns

t

SS

0.594

0.098

0.028

MIN

7

4.75

2.7

TYP

MAX

28

5.50

5.5

V

mA

UNITS

0.600

0.100

0.030

1024

0.606

0.102

V

0.102

0.032

Clock

Cycles

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Maxim Integrated

│

2

MAX16821A/MAX16821B/

MAX16821C

Electrical Characteristics (continued)

PARAMETER

OSCILLATOR

Switching Frequency Range

R

T

= 500kΩ

Switching Frequency

f

SW

R

T

= 120kΩ

R

T

= 39.9kΩ

Switching Frequency Accuracy

CLKOUT Phase Shift with

Respect to DH (Rising Edges)

CLKOUT Phase Shift with

Respect to DL (Rising Edges)

CLKOUT Output-Voltage Low

CLKOUT Output-Voltage High

SYNC Input High Pulse Width

SYNC Input Clock High

Threshold

SYNC Input Clock Low

Threshold

SYNC Pullup Current

SYNC Power-Off Level

INDUCTOR CURRENT LIMIT

Average Current-Limit Threshold

Reverse Current-Limit Threshold

Cycle-by-Cycle Current Limit

Cycle-by-Cycle Overload

CURRENT-SENSE AMPLIFIER

CSP to CSN Input Resistance

Common-Mode Range

Input Offset Voltage

Amplifier Voltage Gain

3dB Bandwidth

Transconductance

Open-Loop Gain

R

CS

V

CMR(CS)

V

OS(CS)

A

V(CS)

f

3dB

g

m

A

VL(CE)

V

IN

= 7V to 28V

V

CLR

V

CL

CSP to CSN

V

CSP

to V

CSN

= 75mV

V

OL

V

OH

t

SYNC

V

SYNCH

V

SYNCL

I

SYNC_

OUT

OFF

High-Power Synchronous HBLED

Drivers with Rapid Current Pulsing

(V

CC

= 5V, V

DD

= V

CC

, T

A

= T

J

= -40°C to +125°C, unless otherwise noted. Typical values are at T

A

= +25°C.) (Note 1)

SYMBOL

CONDITIONS

MIN

125

120

495

1515

-5

-8

180

degrees

180

0.4

4.5

200

2

0.4

V

RT/SYNC

= 0V

250

500

0.4

V

ns

V

µA

V

125

521

1620

TYP

MAX

1500

130

547

1725

+5

+8

%

kHz

UNITS

kHz

120kΩ < R

T

≤ 500kΩ

40kΩ ≤ R

T

≤ 120kΩ

f

SW

= 125kHz, MODE connected

to SGND

f

SW

= 125kHz, MODE connected

to V

CC

I

SINK

= 2mA

I

SOURCE

= 2mA

V

SYNC_

26.4

27.5

-2.0

60

260

4

33.0

mV

ns

kΩ

0

0.1

34.5

4

550

50

5.5

V

mV

V/V

MHz

µS

dB

CURRENT-ERROR AMPLIFIER (TRANSCONDUCTANCE AMPLIFIER)

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Maxim Integrated

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3

MAX16821A/MAX16821B/

MAX16821C

Electrical Characteristics (continued)

PARAMETER

Common-Mode Voltage Range

DIFF Output Voltage

Input Offset Voltage

SYMBOL

V

CMR

(DIFF)

High-Power Synchronous HBLED

Drivers with Rapid Current Pulsing

(V

CC

= 5V, V

DD

= V

CC

, T

A

= T

J

= -40°C to +125°C, unless otherwise noted. Typical values are at T

A

= +25°C.) (Note 1)

CONDITIONS

MIN

0

V

SENSE+

= V

SENSE-

= 0V

MAX16821A

MAX16821B/MAX16821C

MAX16821A

Amplifier Voltage Gain

A

V(DIFF)

MAX16821B

MAX16821C

MAX16821A, C

DIFF

= 20pF

3dB Bandwidth

f

3dB

MAX16821B, C

DIFF

= 20pF

MAX16821C, C

DIFF

= 20pF

SENSE+ to SENSE- Input

Resistance

OUTV AMPLIFIER

Gain-Bandwidth Product

3dB Bandwidth

Output Sink Current

Output Source Current

Maximum Load Capacitance

OUTV to (CSP - CSN) Transfer

Function

Input Offset Voltage

VOLTAGE-ERROR AMPLIFIER (EAOUT)

Open-Loop Gain

Unity-Gain Bandwidth

EAN Input Bias Current

Error Amplifier Output

Clamping Voltage

INPUTS (MODE AND OVI)

MODE Input-Voltage High

MODE Input-Voltage Low

MODE Pulldown Current

OVI Trip Threshold

OVI Hysteresis

OVI Input Bias Current

OVP

TH

OVI

HYS

I

OVI

V

OVI

= 1V

4

1.244

5

1.276

200

0.2

2

0.8

6

1.308

V

µA

V

mV

µA

A

VOLEA

f

GBW

I

B(EA)

V

CLAMP

(EA)

TYP

MAX

1.0

UNITS

V

LED CURRENT SIGNAL DIFFERENTIAL VOLTAGE AMPLIFIER (DIFF)

V

CM

V

OS(DIFF)

0.6

-3.7

-1.5

0.992

5.85

18.5

1

6

20

1.7

1600

550

50

30

10

100

60

20

4

1

30

80

50

+3.7

+1.5

1.008

6.1

21.5

mV

V/V

MHz

kHz

MAX16821A

R

VS

MAX16821B

MAX16821C

V

OUTV

= 2V

V

OUTV

= 2V

kΩ

MHz

µA

pF

137.7

V/V

mV

dB

MHz

+0.2

940

µA

mV

4mV ≤ C

SP

– C

SN

≤ 32mV

132.5

135

1

70

3

V

EAN

= 2V

With respect to V

CM

-0.2

905

+0.03

930

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Maxim Integrated

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4

MAX16821A/MAX16821B/

MAX16821C

Electrical Characteristics (continued)

PARAMETER

ENABLE INPUT (EN)

EN Input-Voltage High

EN Input Hysteresis

EN Pullup Current

THERMAL SHUTDOWN

Thermal Shutdown

Thermal-Shutdown Hysteresis

I

EN

EN rising

SYMBOL

High-Power Synchronous HBLED

Drivers with Rapid Current Pulsing

(V

CC

= 5V, V

DD

= V

CC

, T

A

= T

J

= -40°C to +125°C, unless otherwise noted. Typical values are at T

A

= +25°C.) (Note 1)

CONDITIONS

MIN

2.437

13.5

TYP

2.5

0.28

15

165

20

16.5

MAX

2.562

UNITS

V

µA

°C

Note 1:

All devices are 100% production tested at +25°C. Limits over temperature are guaranteed by design.

Note 2:

Does not include an error due to finite error amplifier gain. See the

Voltage-Error Amplifier

section.

Typical Operating Characteristics

(V

IN

= 12V, V

DD

= V

CC

= 5V, T

A

= +25°C, unless otherwise noted.)

MAX16821A toc01

9

SUPPLY CURRENT (mA)

8

7

6

5

4

3

2

1

0

100

EXTERNAL CLOCK

NO DRIVER LOAD

V

IN

= 24V

V

IN

= 12V

V

IN

= 5V

MAX16821A toc02

65

SUPPLY CURRENT (mA)

60

5.4

5.3

5.2

V

CC

(V)

5.1

5.0

4.9

4.8

4.7

V

IN

= 7V

V

IN

= 24V

V

IN

= 12V

55

50

45

40

V

IN

= 12V

C

DH/DL

= 22nF

-40

-15

10

35

60

85

TEMPERATURE (°C)

4.6

4.5

0

15 30 45 60 75 90 105 120 135 150

V

CC

LOAD CURRENT (mA)

300

500

700

900 1100 1300 1500

FREQUENCY (kHz)

DRIVER RISE TIME

vs. DRIVER LOAD CAPACITANCE

MAX16821A toc04

DRIVER FALL TIME

vs. DRIVER LOAD CAPACITANCE

MAX16821A toc05

200

180

160

140

t

R

(ns)

100

80

60

40

20

0

5

10

DL

15

20

DH

120

100

80

60

HIGH-SIDE DRIVER (DH) SINK

AND SOURCE CURRENT

MAX16821A toc06

C

LOAD

= 22nF

V

IN

= 12V

f

F

(ns)

40

20

0

DL

DH

25

0

5

10

15

20

25

LOAD CAPACITANCE (nF)

100ns/div

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Maxim Integrated

│

5

MAX16821A toc03

10

SUPPLY CURRENT (IQ) vs. FREQUENCY

70

SUPPLY CURRENT vs. TEMPERATURE

5.5

V

CC

LOAD REGULATION vs. V

IN

2A/div

MAX16821B

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