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MAX16821CATI+

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24
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
(V
CC
connected to IN). These devices operate from a
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
MAX16821A/MAX16821B/MAX16821C
High-Power Synchronous HBLED
Drivers with Rapid Current Pulsing
________________________________________________________________
Maxim Integrated Products
1
Q1
HIGH-FREQUENCY
PULSE TRAIN
C2
Q3
L1
R1
V
LED
C1
7V TO 28V
.
CSP
DL
DH
PGND
EN
IN
I.C.
OVI
CLP
Q2
MAX16821
Simplified Diagram
19-0881; Rev 2; 1/10
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.
EVALUATION KIT
AVAILABLE
Typical Operating Circuit and Selector Guide appear at end
of data sheet.
Ordering Information
+
Denotes a lead(Pb)-free/RoHS-compliant package.
*
EP = Exposed pad.
PART TEMP RANGE
PIN-
PACKAGE
MAX16821AATI+
-40°C to +125°C 28 TQFN-EP*
MAX16821BATI+
-40°C to +125°C 28 TQFN-EP*
MAX16821CATI+
-40°C to +125°C 28 TQFN-EP*
MAX16821A/MAX16821B/MAX16821C
High-Power Synchronous HBLED
Drivers with Rapid Current Pulsing
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(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)
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.
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 (V
BST
- V
LX
) + 0.3V
DL to PGND................................................-0.3V to (V
DD
+ 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
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
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Internal LDO on 7 28
Input-Voltage Range V
IN
Internal LDO off (V
CC
connected to V
IN
) 4.75 5.50
V
Quiescent Supply Current I
Q
V
EN
= V
CC
or SGND, no switching 2.7 5.5 mA
LED CURRENT REGULATOR
V
IN
= V
CC
= 4.75V to 5.5V, f
SW
= 500kHz
(MAX16821A)
0.594 0.600 0.606
V
IN
= 7V to 28V, f
SW
= 500kHz
(MAX16821A)
0.594 0.600 0.606
V
IN
= V
CC
= 4.75V to 5.5V, f
SW
= 500kHz
(MAX16821B)
0.098 0.100 0.102
V
IN
= 7V to 28V, f
SW
= 500kHz
(MAX16821B)
0.098 0.100 0.102
V
IN
= V
CC
= 4.75V to 5.5V, f
SW
= 500kHz
(MAX16821C)
0.028 0.030 0.032
Differential Set Value
(V
SENSE
+ to V
SENSE-
) (Note 2)
V
IN
= 7V to 28V, f
SW
= 500kHz
(MAX16821C)
0.028 0.030 0.032
V
Soft-Start Time t
SS
1024
Clock
Cycles
STARTUP/INTERNAL REGULATOR
V
C C
U nd er vol tag e Lockout ( U V LO ) UVLO V
CC
rising 4.1 4.3 4.5 V
UVLO Hysteresis V
CC
falling 200 mV
V
CC
Output Voltage V
IN
= 7V to 28V, I
SOURCE
= 0 to 60mA 4.85 5.10 5.30 V
MOSFET DRIVER
Output Driver Impedance Low or high output, I
SOURCE/SINK
= 20mA 1.1 3 Ω
Output Driver Source/Sink Current I
DH
, I
DL
4A
Nonoverlap Time t
NO
C
DH/DL
= 5nF 35 ns
MAX16821A/MAX16821B/MAX16821C
High-Power Synchronous HBLED
Drivers with Rapid Current Pulsing
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(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)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
OSCILLATOR
Switching Frequency Range 125 1500 kHz
R
T
= 500kΩ 120 125 130
R
T
= 120kΩ 495 521 547Switching Frequency f
SW
R
T
= 39.9kΩ 1515 1620 1725
kHz
120kΩ < R
T
≤ 500kΩ -5 +5
Switching Frequency Accuracy
40kΩ ≤ R
T
≤ 120kΩ -8 +8
%
CLKOUT Phase Shift with
Respect to DH (Rising Edges)
f
SW
= 125kHz, MODE connected to SGND 180
CLKOUT Phase Shift with
Respect to DL (Rising Edges)
f
SW
= 125kHz, MODE connected to V
CC
180
Degrees
CLKOUT Output-Voltage Low V
OL
I
SINK
= 2mA 0.4 V
CLKOUT Output-Voltage High V
OH
I
SOURCE
= 2mA 4.5 V
SYNC Input High Pulse Width t
SYNC
200 ns
SYNC Input Clock High Threshold V
SYNCH
2V
SYNC Input Clock Low Threshold V
SYNCL
0.4 V
SYNC Pullup Current I
SYNC_OUT
V
RT/SYNC
= 0V 250 500 µA
SYNC Power-Off Level V
SYNC_OFF
0.4 V
INDUCTOR CURRENT LIMIT
Average Current-Limit Threshold V
CL
CSP to CSN 26.4 27.5 33.0 mV
Reverse Current-Limit Threshold V
CLR
CSP to CSN -2.0 mV
Cycle-by-Cycle Current Limit CSP to CSN 60 mV
Cycle-by-Cycle Overload
V
CSP
to V
CSN
= 75mV 260 ns
CURRENT-SENSE AMPLIFIER
CSP to CSN Input Resistance R
CS
4kΩ
Common-Mode Range V
CMR
(
CS
)
V
IN
= 7V to 28V 0 5.5 V
Input Offset Voltage V
OS(CS)
0.1 mV
Amplifier Voltage Gain A
V(CS)
34.5 V/V
3dB Bandwidth f
3dB
4 MHz
CURRENT-ERROR AMPLIFIER (TRANSCONDUCTANCE AMPLIFIER)
Transconductance g
m
550 µS
Open-Loop Gain A
VL(CE)
50 dB
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24

MAX16821CATI+

Mfr. #:
Buy MAX16821CATI+
Manufacturer:
Maxim Integrated
Description:
LED Lighting Drivers Synchronous HB w/Rapid Current Puls
Lifecycle:
New from this manufacturer.
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