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Key Specifications
Part Number Description Status Channels(.) Vin (Min)(V) Vin (Max)(V) Vout (Min)(V) Vout (Max)(V) Isw (Peak)(A) Switching Frequency(Max)(kHz) Type LED Current Per Channel(mA) LED(.) Topology Duty Cycle(Max)(%) Shutdown Current(Max)(μA) Peak Efficiency(%) Operating Temperature Range(°C) Pin/Package EV Kit Available?
UM1661 PFM Mode Step-up DC-DC Converter with 1.6A Peak Current Limit ACTIVE 4 2 6 24 1.5 2000 Inductive 20 32 Boost 0 1 85 -40 to 85 6/SOT23 Y
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Product Description
The UM1661 PFM step-up DC/DC Converter drives white LEDs with a constant current to provide backlight in cell phones, PDAs, and other hand-held devices. It features allowing series connection of the white LEDs so that the LED currents are identical for uniform brightness. An enable input can be pulsed repeatedly to adjust LEDs brightness. The fast 500kHz to 2MHz operation frequency allows for smaller capacitor and inductor. Fault condition protection uses cycle-by-cycle current limiting to sense maximum inductor current and over-voltage protection. The 0.2V low reference voltage minimizes the power loss across the current sense resistor.
The converter can operate from 2V to 6V, and capable of delivering maximum 200mA output current at 4-LEDs application with 3V input voltage. Quiescent current drawn from power source is as low as 120uA. All of these features make UM1661 be suitable for the portable devices, which are supplied by a single battery.
- Up to 24V Output Voltage
- Wide Operation Range: 2V to 6V
- Maximum 2MHz Operating Frequency
- PWM Dimming Control
- Shutdown Current <1μA
- Current Limit Cycle-by-Cycle
- Low Current Sense Threshold: 200mV
- 24V Over Output Voltage Protection
- Compact SOT23-6 Package
Typical Application Circuit

- Compact Back Light Module
- Power Source for LED
- Constant Current Source
Pin Configurations  

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