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Home > Step-Up DC-DC Converter
UC3551 Datasheet


The UTC UC3551 is a step-up DC/DC converter with high
efficiency and low start-up voltage. It is operaded in stable
waveforms without external compensate. This device incorporates
an adaptive current mode PWM control loop in which an error
amplifier, ramp generator, comparator, switch pass element and
driver are included. Besides, this circuit provides a stable and high
efficient operation over a wide range of load currents.  
The UTC UC3551 features high switching rate which is up to 450
KHz, making the external component counts less required.
Moreover, it features 17μA low quiescent current, which makes the
battery life longer. The low start-up input voltage below 1V makes
UTC UC3551 suitable for 1 to 4 battery cells applications of
providing up to 300mA output current.  
Two external resistors determine the value of the output voltage.
The external power devices (NMOS or NPN) are derived by both
internal 2A switch and driver.  
The UTC UC3551 is intended to be used in PDA, DSC, LCD
Panel, RF-Tags, MP3, portable instrument and wireless equipment.

* Low Start-up Input Voltage is as Low as 1.0V
* Efficiency up to 90%
* High Supply Capability to Deliver 3.3V 100mA with 1 Alkaline Cell
* Quiescent (Switch-off) Supply Current: 17µA
* Zero Shutdown Mode Supply Current
* Fixed Switching Frequency: 450KHz
* Both Internal and External Power Switches for Maximum Flexibility
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