GENERAL DESCRIPTION
The AX2008
is a step-up current mode PWM DC/DC converter with built-in
power
MOSFET and eight channel current sources. It is designed for
driving white LED arrays for medium size LCD panel backlight
applications.
The AX2008
features dynamic output voltage control function, which
automatically chooses the lowest sense voltage of multiple channels
to regulate the feedback voltage of step-up converter. Through the
function, the AX2008 is able to dynamically adjust output voltage
of step-up converter to optimize the system power efficiency.The
internal step-up converter provides soft-start feature which is
determined byexternal compensation components. The switching
frequency is programmable by anexternal resistor, which is helpful
for optimizing the external components sizes and improving the
efficiency. In shutdown mode, current consumption of converter can
be reduced to only 1uA.
The AX2008
provides eight channels constant current sinks with maximum
±3%
current matching. The LED current can be adjusted by an external
resistor, which provides users flexibility to control the light
intensity of LEDs. In addition, users can precisely adjust LED
brightness from 0% to 100% via PWM pin with pulse width
modulation.
The AX2008
has multiple features to protect the converter from fault
conditions. The adjustable over-voltage protection (OVP) function
prevents the converter when output loading is open. Over-current
protection (OCP) function ensures the system reliability and
provides consistent operation. Over-temperature protection (OTP)
function protects the converter from overheating in various
application conditions.
The AX2008
provides space-saving, thermal enhanced 20-pin TSSOP exposed pad
and QFN 4mm x 4mm packages as well to handle power dissipation more
efficiently.
FEATURES
- Operating Voltage from 4.5V to 25V
- Output Voltage from Input Voltage to 40V
- Dynamic Output Voltage Control to Optimize System
Efficiency
- 90% Efficiency for Boost Converter
- Integrated Power MOSFET for Boost Converter
- Programmable Switching Frequency
- Soft Start Function
- External Compensation Network
- Eight Constant Current Output Sink Channels
- LED Current Set by an External Resistor.
- Output Current Matching : ±3% (max.) between Channels
- LED Brightness Dimming by External PWM Signal.
- Adjustable Over-Voltage Protection
- Over-Temperature Protection
- RoHS Compliant
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