SGM3124 Datasheet, PDF (13/17 Pages) SG Micro Corp – White LED Charge Pump Current Source with PWM Brightness Control

SGM3124
White LED Charge Pump Current
Source with PWM Brightness Control
APPLICATION INFORMATION
Analog Dimming Using ISET Pin
The ISET pin can be used to connect an analog dc signal in the range of 0mV to 600mV (EN1 = EN2 = 1) for analog
dimming of the white LEDs. For an input voltage of 0V at ISET, the current is at its maximum, whereas at 600mV, the
LED current is zero. The maximum current is:
 For EN2 = EN1 = 1: I_LED = V_SET/R_SET × K = 0.6V/6000 × 255 = 25.5mA per LED
 For EN2 =1, EN1 = 0: I_LED = V_SET/R_{SE T}× K = 0.4V/6000 ×255 = 17mA per LED
 For EN2 = 0, EN1 = 1: I_LED = V_SET/R_SET × K = 0.2V/6000 ×255 = 8.5mA per LED
 With EN2, EN1 set to 10 or 01, a voltage of 400mV or 200mV is required to set the LED current to zero.
C2
0.47µF
C1
0.47µF
C2- C1-
C1+ C2+
Li-ion
CIN
VIN
VOUT
Battery
1µF
D1
1µF
EN1 _SGM3124
D2
EN2
D3
ISET GND PGND
V = 0mV to 600mV
6kΩ
SG Micro Corp
www.sg-micro.com
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