AOZ1950 Datasheet, PDF (1/14 Pages) Alpha & Omega Semiconductors – Boost Regulator White LED Driver

AOZ1950
Boost Regulator White LED Driver
General Description
The AOZ1950 is a high-efficiency boost regulator with
internal 60V MOSFET and input protection switch. The
part is designed to drive up to twelve white LEDs in
series. The AOZ1950 supports two dimming control
methods: analog dimming and PWM dimming. In analog
dimming mode, the LED current can be linearly adjusted
for ±12% with a DC voltage on DIM pin. In PWM dimming
mode, the LEDs can be turned on and off by toggling EN
pin with a square wave, and the brightness is
proportional to the duty cycle of the control signal.
AOZ1950 is a fixed OFF pulse regulator with adaptive
pulse width as a function of input and output voltage.
Typical switching frequency is 800kHz. This allows the
use of low-profile inductor and capacitors.
The AOZ1950 works from a 2.7V to 5.5V input voltage
range supporting a wide range of applications. Other
features include cycle-by-cycle current limit, Input voltage
short circuit protection switch, open-LED over-voltage
protection, input under-voltage lockout, thermal
shutdown and soft-start.
The AOZ1950 is available in a tiny 3mm x 3mm
10-pin DFN package and is rated over a -40°C to +85°C
operating temperature range.
Features
z 2.7V to 5.5V input voltage range
z 60V/350mΩ internal N-channel MOSFET
z Drives up to 12 White LEDs
z 800kHz typical switching frequency with adaptive
pulse width control
z 150ns nominal OFF pulse
z 300mV feedback regulation
z Analog dimming via DIM pin
z PWM dimming via EN pin
z Cycle-by-cycle current limit
z Short circuit protection switch
z Open LED over-voltage protection
z Thermal shutdown protection
z Internal soft-start
z Small 3mm x 3mm DFN package
Applications
z Portable DVD Players
z GPS Systems
z Smart Phones
z Sub Notebook PC
Typical Application
L1
22μH
VIN
2.7V-5.5V
R1
1.5kΩ
C3
22nF
C1
4.7μF
IND
VIN
LX
VOUT
AOZ1950
DIM
PGND
AGND
EN
COMP
C4
1nF
FB
C2
0.47μF
R2
15Ω
Rev. 1.0 January 2010
www.aosmd.com
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