EUP2794
White LED Driver with 1X /1.5X
High-Efficiency Charge Pump
DESCRIPTION
The EUP2794 is a low noise, constant frequency
charge pump that uses a dual mode load switch (1X)
and fractional (1.5X) conversion to maximize
efficiency for white LED applications. The EUP2794
delivers up to 80mA of load current and provides four
regulated current sources, each capable of driving up to
20mA through white LEDs. All LED pin currents are
regulated, constant and tightly matched to achieve
uniformity of brightness across the LCD backlight. The
switching frequency is 900kHz.(typ.) to keep the
conducted noise spectrum away from sensitive
frequencies within portable RF devices.
An external resistor (R
SET
) sets the current in each of
the LED outputs. In addition, brightness can be
controlled by both linear and PWM techniques. An
analog voltage between 0V and 3.0V may be applied to
the BRGT pin to linearly vary the LED current. By
adjusting current with BRGT pin , the brightness of the
LEDs can be smoothly varied. Alternatively, a PWM
digital signal can be applied to the SD pin to vary the
perceived brightness of the LED.
The EUP2794 is available in a 16-pin 3mm
×
3
mm
QFN package.
FEATURES
Regulated Current Sources with 0.6%
Mis-matching between any Two Outputs
High Efficiency 1.5X Charge Pump
Drives One, Two, Three or Four White LEDs
2.7V to 5.5V Input Voltage
Up to 80mA Output Current
Analog or PWM Brightness Control
Soft Start Function
Low Shutdown Current
900kHz Switching Frequency (typ.)
Tiny 3mm
×
3
mm QFN-16 Package
RoHS Compliant and 100% Lead(Pb)-Free
APPLICATIONS
White LED Backlighting
1-Cell Li-Ion battery-operated equipment
including PDAs, hand-held PCs, cellular
phones
Typical Application Circuit
Figure 1.
DS2794 Ver0.5 Mar. 2006
1
EUTECH [ EUTECH MICROELECTRONICS INC ]
