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UC3655 Datasheet

500mA SYNCHRONOUS STEP-DOWN DC/DC CONVERTERS


DESCRIPTION
 
The UTC UC3655 is a synchronous-rectification type DC/DC
converters with a built-in 0.6Ω P-channel driver transistor and 0.7Ω
N-channel switching transistor, which designed to allow the use of ceramic
capacitors. Using only a coil and two capacitors connected externally, the
UC3655 enable a high efficiency, stable power supply with an output
current of 500mA to be configured. Its operating voltage is 2.0V and the
output voltage is programmable in a range from 0.9V to 4.0V in
increments of 0.1V (accuracy: ±2.0%) internally. The oscillation frequency is 1.2MHz.
For operation mode, it is PWM control in the UTC UC3655, the UTC
UC3655 series is automatic PWM/PFM switching control, allowing fast
response, low ripple and high efficiency over the full range of load.
Internal soft start and current control functions are built in it. All
circuits are shutdown to reduce current consumption to as low as 1.0μA or
less during standby mode. With the built-in Under Voltage Lock Out
(U.V.L.O.) function, when input voltage becomes 1.4V or lower the internal
P channel driver transistor is forced OFF.
 



 
FEATURES
 
* Very High Efficiency 92%
* Low Ripple Rejection Voltage 10mV
* Output Current 500mA @VIN=3.0V, VOUT=1.8V
* Oscillation Frequency is 1.2MHz
* With PWM / PFM Automatic Switching Control  
* Maximum Duty Ratio is 100%
* Ceramic Capacitor Available


 
TYPICAL APPLICATION CIRCUIT

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