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Features
2.7V to 5.5V Input Voltage
Regulated Output Voltage (VOUT = 4.35V)
Regulated IDx with ±0.3% matching between constant current outputs
High Efficiency 3/2 Boost function
Drives one, two, or three white LEDs with no bias resistor losses
Drives auxiliary keypad LEDS in voltage mode
Up to 80mA total output current
Active-High Enable
Active-High PWM Control Pin for independent control of current sources
Very small solution size
1µA(max) shutdown current
500kHz switching frequency (typ.)
Linear regulation generates predictable noise spectrum
LLP-14 package: 4.0mm X 3.0mm X 0.8mm
Description The LM3570 device provides a complete LED driver solution for wireless handsets and other portable devices using a display
and keypad. With three constant current sources, up to three white LEDs can be used for display lighting with excellent current
matching (0.3% typ.). The regulated 4.35V output voltage is perfect for driving auxiliary keypad LEDs in voltage mode.
The LM3570 utilizes a high efficiency 3/2 CMOS charge-pump with a pre-regulation loop that minimizes conducted noise on the
input. It accepts an input voltage range from 2.7V to 5.5V and maintains a constant current determined by the current through
an external RSET resistor.
The device supplies up to 80mA of total load current to accommodate any combination of up to three white LEDs, and additional
current from VOUT. The switching frequency is set at 500kHz. (typ.) to keep the conducted noise spectrum away from sensitive frequencies within
portable RF devices.
By applying a pulse width modulated (PWM) signal to the PWM pin, the user has the ability to independently control the brightness
of the regulated current source outputs without shutting down the regulated output voltage.
Applications
Portable devices using white or blue LEDs with display and backlight or frontlight
1-Cell LiIon battery-operated equipment including PDAs, hand-held PCs and cellular phones
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Also Recommended
| LM2796▲ | 7 Led Outputs |
| LP3936 | 6 White LED And 1 RGB Drivers, Inductive Boost |
| LM2793▲ | 2 LEDs Outputs, LLP |
| LM2794▲ | 4 LED Outputs With Active-Low Shutdown Pin |
| LM2795▲ | 4 LED Outputs With Active-High Shutdown Pin |
| LP3933 | 6 White LED And 2 RGB Drivers, Inductive Boost |
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