MAX17061 반도체 회로 부품 판매점
8-String White LED Driver
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 Maxim Integrated Products |
19-3211; Rev 0; 1/08
www.DataSheet4U.com
8-String White LED Driver with
SMBus for LCD Panel Applications
General Description
The MAX17061 is a high-efficiency driver for white light-
emitting diodes (LEDs). It is designed for large liquid-
crystal displays (LCDs) that employ an array of LEDs as
the light source. An internal switch current-mode step-up
controller drives the LED array, which can be configured
for up to eight strings in parallel and 10 LEDs per string.
Each string is terminated with ballast that achieves ±1.5%
current-regulation accuracy between strings, ensuring
even LED brightness. The MAX17061 has a wide input-
voltage range from 4.5V to 26V, and provides a fixed
25mA or adjustable 15mA to 30mA full-scale LED current.
The MAX17061 internally generates a DPWM signal for
accurate WLED dimming control. The DPWM frequency
is resistor programmable, while DPWM duty cycle is con-
trolled directly from an external PWM signal or through a
control word through the MAX17061’s SMBus™ inter-
face. This DPWM control provides a dimming range with
8-bit resolution and supports Intel display-power-saving
technology (DPST) to maximize battery life.
The MAX17061 has multiple features to protect the con-
troller from fault conditions. Separate feedback loops
limit the output voltage under any circumstance, ensur-
ing safe operation. Once an open string is detected,
the string is disabled while other strings operate nor-
mally. The MAX17061 also features short LED detec-
tion. The shorted strings are also disabled after a 2ms
fault blanking interval. The controller features cycle-by-
cycle current limit to provide stable operation and soft-
start capability. If the MAX17061 is in current-limit
condition, the step-up converter is latched off after an
internal timer expires. A thermal-shutdown circuit pro-
vides another level of protection.
The MAX17061’s step-up controller features an internal
150mΩ (typ), 45V (max) power MOSFET with local cur-
rent-sense amplifier for accurate cycle-by-cycle current
limit. This architecture greatly simplifies the external cir-
cuitry and saves PCB space. Low-feedback voltage at
each LED string 625mV (typ) at 25mA LED current helps
reduce power loss and improve efficiency. The
MAX17061 features selectable switching frequency
(500kHz, 750kHz, or 1MHz), which enables a wide vari-
ety of applications that can trade off component size for
operating frequency.
The MAX17061 is available in a thermally enhanced
28-pin, 4mm x 4mm Thin QFN package.
Applications
Notebook, Subnotebook,
and Tablet Computer
Displays
Automotive Systems
Handy Terminals
Features
o Accurate Dimming Control Using SMBus, PWM
Interface
o Dimming Range with 8-Bit Resolution
o Adjustable DPWM Frequency with 1.5% Accuracy
o Up to Eight Parallel Strings Multiple Series-
Connected LEDs
o ±1.5% Current Regulation Accuracy Between
Strings
o Low String Feedback Voltage: 625mV at 25mA
LED Current
o Full-Scale LED Current Adjustable from 15mA to
30mA, or Preset 25mA
o Open and Short LED Protections
o Output Overvoltage Protection
o 0.15Ω Internal HV Power MOSFET (45V max)
o Wide Input-Voltage Range from 4.5V to 26V
o 500kHz/750kHz/1MHz Selectable Switching
Frequency
o Small 28-Pin, 4mm x 4mm, Thin QFN package
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX17061ETI+ -40oC to +85oC 28 Thin QFN (4mm x 4mm)
+Denotes a lead-free package.
Simplified Operating Circuit
L1 D1
VIN
VOUT
VDD IN
VCC
ISET
LX1, 2
PGND1, 2
CCV OV
PWM
CLK
DATA
MAX17061
PWMI
PWMO
FB1
GND
N.C. OSC
FB2
FB3
FB4
SCL FB5
FB6
SDA FB7
FSET FB8
EP
R1
R2
Pin Configuration appears at end of data sheet.
SMBus is a trademark of Intel Corp.
________________________________________________________________ Maxim Integrated Products 1
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.
www.DataSheet4U.com
8-String White LED Driver with
SMBus for LCD Panel Applications
ABSOLUTE MAXIMUM RATINGS
IN to GND ..............................................................-0.3V to +28V
FB_, LX_ to GND ....................................................-0.3V to +45V
PGND_ to GND......................................................-0.3V to +0.3V
VCC, VDD, PWMI, SDA, SCL to GND ........................-0.3V to +6V
ISET, CCV, PWMO, FSET, OSC,
OV to GND ................................................-0.3V to VCC + 0.3V
Continuous Power Dissipation (TA = +70°C)
28-Pin Thin QFN (derate 16.9mW/°C above +70°C)...1667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°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
(Circuit of Figure 1, VIN = 12V, CCCV = 0.022µF, RCCV = 5.1kΩ, VISET = VOSC = VDD = VCC, RFSET = 464kΩ, VPWMI = GND,
TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
IN Input Voltage Range
IN Quiescent Current
IN Quiescent Current
VCC Output Voltage
VCC Current Limit
VCC UVLO Threshold
BOOST CONVERTER
LX On-Resistance
LX Leakage Current
Operating Frequency
OSC High-Level Threshold
CONDITIONS
VIN = VCC
VCC = open
MAX17061 is enabled at
minimum brightness, no load
VIN = 26V
VIN = VCC = 5V
MAX17061 is disabled, VIN = 12V
MAX17061 is enabled, 6V < VIN < 26V, 0 < IVCC < 10mA
MAX17061 is disabled, VIN = 12V
VCC is forced to 4.5V
Rising edge, typical hysteresis = 85mV
MIN
4.5
5.5
4.7
3.90
15
4.00
TYP
1.24
5.0
4.35
40
4.25
MAX
5.5
26.0
UNITS
V
2 mA
10 µA
5.3
V
4.80
70 mA
4.45 V
20mA from LX_ to PGND
45V on LX_
VOSC = VCC
VOSC = open
VOSC = GND
0.15 0.3
Ω
1 µA
0.9 1.0 1.1 MHz
675 750 825
kHz
450 500 550
VCC -
0.4
V
OSC Midlevel Threshold
1.5
VCC -
V
2.0
OSC Low-Level Threshold
Minimum Duty Cycle
Maximum Duty Cycle
LX Current Limit
CONTROL INPUT
SDA, SCL Logic Input-High Level
SDA, SCL Logic Input-Low Level
PWMI Logic Input-High Level
PWMI Logic Input-Low Level
PWM mode (Note 1)
Pulse skipping, no load (Note 1)
Duty cycle = 75% (Note 1)
0.4
10
0
94.0 95.5 97.0
1.6
2.1
0.8
2.1
0.8
V
%
%
A
V
V
V
V
2 _______________________________________________________________________________________
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MAX17061 led
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