PAM2801 Datasheet, PDF (1/9 Pages) Power Analog Micoelectronics – 1W High Power White LED Driver

PAM2801
1W High Power White LED Driver
Features
General Description
n LED Power Efficiency: up to 90%
n LED Current Accuracy:±3%(V = _IN 3.2V to 1.1V
@V_F=3.4V)
n Low Start-Up Voltage: 0.9V(I = _LED 243mA)
n Low Hold Voltage:0.65V(I_LED=95mA)
n Internal 2A MOSFET Switch
n 1.0MHz Switching Frequency
n Uses Small,Low Profile External Components
n Low R : _DS(ON) 100mΩ (TYP.)
n Open LED Protection
n Over Temperature Protection
n Low Profile SOT-23 Package
n Pb-Free Package
Applications
n White LED Torch (Flashlight)
n White LED Camera Flash
n DSC(Digital Still Camera)Flash
n Cellular Camera Phone Flash
n PDA Camera Flash
n Camcorder Torch(Flashlight) Lamp
The PAM2801 is a step-up DC-DC converter that
delivers a regulated output current. The device
switches at a 1.0MHz constant frequency,
allowing for the use of small value external
inductor and ceramic capacitors.
The PAM2801 is targeted to be used for driving
1W white LED from a 0.9V to 3.2V input. The LED
current can be programmed by the external
current sense resistor, Rs, connected between the
feedback pin (FB) and ground. A low 95mV
feedback voltage reduces the power loss in the Rs
for better efficiency. With its internal 2A, 100mΩ
NMOS switch, the device can provide high
efficiency even at heavy load.
LED dimming can be done by using a DC voltage
applied to the FB pin and a pulse width modulation
(PWM) signal applied to the FB pin or SHDN pin.
During the shutdown mode, the feedback resistor
Rs and the load are completely disconnected and
the current consumption is reduced to less than
1uA.
The PAM2801 is available in the 6-lead SOT-23-6
package.
Typical Application
2.2uH
1
SW
6 VIN VOUT ⁵
C_IN
PAM2801
V_IN
10uF
SHDN FB 3
OFF ON 4
GND
2
1W
WLED
C_O
R_S
10uF
I_LED=350mA,R_S=0.27Ω
Block Diagram
95mV
Reference
+
A1
-
FB
VOUT VIN
Comparator
-
Rc ^A2
+
Cc
PWM Logic
And Driver
Σ
Ramp
Generator
SW
+
-
SHDN _Shutdown
And
Soft-start
1.0MHz
Oscillator
GND
Power Analog Microelectronics,Inc
www.poweranalog.com
1
08/2007