DESIGN IDEAS L Single-Wire Camera LED Charge
Pump Allows Multiple Output
Current Levels With Single-Resistor
Programmability
by Mohammed H. Jafri
Introduction
time, the LTC3218 features a built-in
timer. This timer shuts down the part
if it has been enabled in flash-mode
(ENF = HIGH) for more than 2 seconds.
The timer is reset by bringing the part
into shutdown and re-enabling it. ENT ILED LOW LOW SHUTDOWN LOW HIGH 1029/RSETT HIGH LOW 2965/RSETF HIGH HIGH 3993/RSETF Linear Technology Magazine October 2007 90 Multiple Current Ratios
LED drivers often use external resistors to program LED current. The LED
current is related to the programming
resistor current through a fixed ratio.
By employing multiple current ratios,
the LTC3218 can be programmed for 80
70
60
50mA
150mA
300mA 50
40 …