FAN5616 Datasheet, PDF (10/14 Pages) Fairchild Semiconductor – High-Efficiency, Constant-Current LED Driver with Adaptive Charge Pump

V_IN
VOUT
EN1/EN2
Smart
Soft-Start
250µS
Smart
Soft-Start
Device in
Low Power
250µS
< 5mS
> 5mS
Figure 5. Smart Soft-Start Timing
V_OUT
Smart Soft-Start
T_STR = 500µS
EN1/EN2
F_PWM >> 1kHz
Duty Ratio = 50%
Figure 6. Smart Soft-Start Timing with 50% PWM
Application Information
LED Brightness Control Methods
1. External R_SET Resistor
The external R_SET resistor sets the maximum LED cur-
rent for LED brightness control.
Table 1. Max. I_LED (EN1=EN2 = Logic “High”)
R_SET (kΩ)
I_LED-MAX (mA)
7.8 15.6 31.2 62.4
20
10
5
2.5
The resistor value establishes the reference current
needed for a constant LED current. To calculate different
R_SET values, use the formula below:
R _SET
= ¹⁵⁶
I_LED
10
FAN5616 Rev. 1.0.0
www.fairchildsemi.com