EVALUATION KIT AVAILABLE
MAX17105
8-String WLED Driver with Integrated Step-Up
Regulator and SMBus/PWM Dimming Capability
General Description
The MAX17105 is a high-efficiency driver for white-light-
emitting diodes (WLEDs). 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 8 strings in parallel and 10 LEDs per string. Each
string is terminated with ballast that achieves ±2% current
regulation accuracy, ensuring even LED brightness. The
MAX17105 has a wide input voltage range from 6V to
28V, and provides adjustable 0 to 30mA full-scale LED
current.
The MAX17105 can internally generate a digitally adjust-
ed pulse-width modulation (DPWM) signal for accurate
WLED dimming control. The DPWM frequency is resis-
tor programmable, while DPWM duty cycle is controlled
directly from an external PWM signal or through a control
word through the MAX17105’s SMBus interface. This
DPWM control provides a dimming range with 8-bit reso-
lution and supports Intel display power-saving technology
(DPST) to maximize battery life. The MAX17105 also has
direct PWM control mode, in which the PWMI directly con-
trols the LED current turn on/off and the SMBus interface
is disabled.
The MAX17105 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 normally.
The MAX17105 also features short LED detection. The
shorted strings are also disabled. The controller features
cycle-by-cycle current limit to provide constant operation
and soft-start capability. If the MAX17105 is in current-
limit condition, the step-up regulator is latched off after an
internal timer expires. A thermal-shutdown circuit provides
another level of protection. When the input overcurrent-
limit fault, thermal shutdown, or output-voltage short con-
dition happens, the input p-channel MOSFET is turned
off and the step-up regulator output is isolated from the
input supply.
The MAX17105 is available in a thermally enhanced,
24-pin, 4mm x 4mm, thin QFN package with exposed pad.
Applications
●● Notebook, Subnotebook,
and Tablet Computer
Displays
●● Handy Terminals
Features
●● 6V to 28V Input Supply Voltage
●● Up to Eight Parallel-String Multiple Series Connected
LEDs
●● 500kHz-to-2MHz Adjustable Switching Frequency
●● 0.15Ω Internal HV Power MOSFET (45V max)
●● Low-String Feedback Voltage: 500mV at 20mA LED
current
●● Full-Scale LED Current Adjustable from 0mA to 30mA
●● ±2% Current Regulation Accuracy Between Strings
●● 100:1 Dimming Ratio at 25kHz Direct PWM
Frequency
●● 100Hz to 30kHz PWMI Input Range for DPWM Mode
and 10kHz ±5% for SMBus Mode
●● 100Hz to 5kHz Adjustable DPWM Frequency
●● Full-Range Dimming with 8-Bit Resolution
●● Open and Short LED Protection
●● Output Overvoltage Protection
●● Thermal Shutdown
●● FAULT Output to Drive p-Channel MOSFET
●● Small 24-Pin, 4mm x 4mm, Thin QFN Package
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX17105ETG+ -40°C to +85°C
24 TQFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Pin Configuration
TOP VIEW
18 17 16 15 14 13
LX 19
12 FB3
PWMI 20
11 FB2
EN 21
SCL 22
MAX17105
10 FB1
9 SGND
SDA 23
8 FAULT
DFSET 24
7 IN
12 3 4 56
THIN QFN
4mm x 4mm
Simplified Operating Circuit appears at end of data sheet.
19-4562; Rev 2; 9/14
