PAM2801 Datasheet Text
1W High Power White LED Driver
PAM2801
Features n LED Power Efficiency: up to 90% n LED Current Accuracy: ± 3%(V IN=3.2V to 1.1 V @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 ponents 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
General Descriptio n
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, 100 mΩ 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 pletely disconnected and the current consumption is reduced to less than 1uA. The PAM2801 is available in the 6-lead SOT-23-6 package.
Applications n n n n n n
White LED Torch (Flashlight) White LED Camera Flash DSC(Digital Still Camera)Flash Cellular Camera Phone Flash PDA Camera Flash Camcorder Torch(Flashlight) Lamp
Typical Application
2.2uH
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Block Diagram
VOUT VIN SW
95mV Reference
1
SW 6 VIN VOUT 5
C IN
+ A1
- parator
Rc Cc
A2 +
PWM Logic And...