AP1603_10

AP1603 STEP-UP DC/DC CONVERTER Description The AP1603 is a high efficiency step-up DC/DC converter for applications using as few as a single NiMH or Li-Ion battery cells. Only four external components are required to deliver a fixed output voltage of 3.3V. The AP1603 starts up from less than 0.9V input with 1mA load. Pulse Frequency Modulation scheme brings optimized performance for applications with light output loading and low input voltages. The output ripple and noise are lower compared with the circuits operating in PSM mode. The PFM control circuit operating in 150KHz (max.) switching rate results in smaller passive components. The space saving SOT26 packages make the AP1603 an ideal choice of DC/DC converter for space conscious applications, like pagers, electronic cameras, and wireless microphones. Pin Assignments ( Top View ) FB 1 GND 2 REF 3 SOT26 AP1603 6 SHDN 5 OUT 7 LX 4 Features • • • • • • • A Guaranteed Start-Up from less than 0.9 V High Efficiency Low Quiescent Current Less Number of External Components needed Low Ripple and Low Noise Space Saving Lead Free Package: SOT26 Lead Free Finish/ RoHS Compliant (Note 1) Applications • • • • • • Pagers Cameras Wireless Microphones Pocket Organizers Battery Backup Suppliers Portable Instruments Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at http://www.diodes.com/products/lead_free.html. AP1603 Document number: DS31131 Rev. 3 - 2 1 of 10 www.diodes.com June 2010 © Diodes Incorporated AP1603 STEP-UP DC/DC CONVERTER Typical Application Circuit (1) VOUT = 5V 1.1V to 5.5V VIN ON OFF 22uH + 47uF SHDN REF 0.1uF GND LX OUT FB + 47uF Fixed Output ( 5V ) (2) VOUT = 3.3V 1.1V to 3.6V VIN ON 22uH + 47uF OFF SHDN REF 0.1uF GND LX OUT FB + 47uF Fixed Output ( 3.3V ) (3) VOUT = Adj 1.1V to 5.5V V IN ON OFF SHDN REF 0.1uF G ND FB LX OUT R2 22uH + 47uF + Output 47uF R1 R2 V OUT = V REF ( 1+ R1 ) AP1603 Document number: DS31131 Rev. 3 - 2 2 of 10 www.diodes.com June 2010 © Diodes Incorporated AP1603 STEP-UP DC/DC CONVERTER Pin Descriptions Pin Name FB GND REF LX OUT SHDN Description Feedback. Ground. 1.2V Reference Voltage. Bypass with a 0.1μF capacitor. N-Channel and P-Channel Power MOSFET Drain. Power Output. OUT provides bootstrap power to the IC. Shutdown Input. Drive high (>80% of VOUT) for operating mode. Drive low (