ADD5207ACPZ Datasheet, PDF (1/16 Pages) Analog Devices – Four-String, White LED Driver for LCD Backlight Applications

Data Sheet
FEATURES
White LED driver based on inductive boost converter
Integrated 40 V MOSFET with 1.5 A peak current limit
Input voltage range: 6 V to 21 V
Maximum output adjustable up to 36 V
600 kHz to 1 MHz adjustable operating frequency
Typical 39 V fixed overvoltage protection (OVP)
Built-in soft start for boost converter
Drives up to 4 LED current strings
LED current adjustable up to 25 mA for each channel
Headroom control to maximize efficiency
Fixed LED dimming frequency: 8 kHz
LED open fault protection
Brightness control with PWM input
Dimming controls
4-channel operation: 90 degree phase shift between
channels
3-channel operation: 120 degree phase shift between
channels
General
Thermal shutdown
Undervoltage lockout
14-lead, 4 mm × 3 mm LFCSP
APPLICATIONS
Notebook PCs, UMPCs, and monitor displays
Four-String, White LED Driver
for LCD Backlight Applications
ADD5207
GENERAL DESCRIPTION
The ADD5207 is a white LED driver for backlight applications
based on high efficiency, current mode, step-up converter tech-
nology. It is designed with a 0.15 Ω, 1.5 A internal switch and a
pin-adjustable operating frequency between 600 kHz and 1 MHz.
The ADD5207 contains four regulated current sources for
uniform LED brightness. Each current source can drive up to
25 mA and the LED-driving current is pin adjustable by an
external resistor. The ADD5207 drives up to four parallel
strings of multiple series-connected LEDs with a ±1.5% current
matching between strings.
The ADD5207 provides phase shift PWM brightness control
methods. LED dimming control is achieved through the PWM
input. The device includes an 8 kHz LED-dimming oscillator
for driving each current source. The ADD5207 operates over an
input voltage range of 6 V to 21 V, but the device can function
with a voltage as low as 5.6 V.
The ADD5207 also has multiple safety protection features to
prevent damage during fault conditions. If any LED is open, the
device automatically disables the faulty current source. The
internal soft start circuit prevents a high inrush current during
startup. Thermal shutdown protection prevents thermal damage.
The ADD5207 is available in a low profile, thermally enhanced,
4 mm × 3 mm × 0.75 mm, 14-lead, RoHS-compliant lead frame
chip scale package (LFCSP) and is specified over the industrial
temperature range of −25°C to +85°C.
V_IN
+
–
C_IN
10µF
C_IN2
0.1µF
TYPICAL APPLICATION CIRCUIT
L1
10µH
1 VIN
D1
C_OUT
14
13
4µF
SW
OVP
9 PWM
ADD5207
OFF ON
C_BYPASS
1µF
R_F
100kΩ
10 _SHDN
8 VDD
2 FSLCT
ISET
3
COMP
11
R_SET
180kΩ
R_C
6.8kΩ
C_C
2.2nF
FB1 4
FB2 5
FB3 6
FB4 7
GND
12
C2
OPEN
Figure 1.
Rev. A
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