The MAX1582/MAX1582Y drive up to six white LEDs in
series with a constant current to provide display backlighting
for two (main and sub-) displays in cell phones
and other handheld devices. This configuration eliminates
the need for ballast resistors and expensive factory
calibration. The proprietary dual-output, step-up
pulse-width modulation (PWM) converter includes a low
RDSON n-channel MOSFET switch for high efficiency and
maximum battery life.
The MAX1582/MAX1582Y utilize 1MHz current-mode
PWM control to allow small input and output capacitors
and a small inductor, while minimizing ripple on the input
supply and avoiding interference to sensitive circuitry in
the equipment. Integrated overvoltage protection (27V
for the MAX1582 and 18V for the MAX1582Y) eliminates
the need for an external zener diode to protect the IC
from open circuit. Flexible dimming control utilizes either
an analog control signal or direct digital PWM control
without external RC filtering. This also increases dimming
accuracy at low brightness levels. The PWM dimming
signal can be any frequency from 200Hz to 200kHz. Softstart
eliminates inrush current during startup.
The MAX1582/MAX1582Y are available in tiny 4 x 4
chip-scale (UCSP™) and 12-pin thin QFN packages.
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