The EMD2794/EMD2795 is a 1.5x/1.0x charge pump that
provides four regulated current sources. It accepts an
input voltage range from 2.7V to 5.5V and maintains a
constant current determined by an external resistor.
The EMD2794/EMD2795 delivers up to 80mA of load current
to accommodate four White LEDs. The switching
frequency is fixed at 1.2MHz to make noise filtering easier.
Brightness control can be done by both linear and PWM
techniques. Linear control is achieved by applying 0V to
3.0V to the BRGT pin to linearly vary the LED current. PWM
technique is to apply a clock to the EN pin to having
brightness varying with clock duty.
Shutdown is done by applying low (high for 2795) to the pin
EN. The VIN current drops to less than 1.0uA in shutdown
mode.
The EMD2794/EMD2795 is available in a TQFN-16 & FBP-16
3x3 package.