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AN009
Tiny Step-Up DC/DC Converter Design
for Portal Single Cell Applications
Abstract
Products such as walkman, pager, electronic
dictionary, MP3 player and PDA , none of them
can escape out of using one cell trend. This
article introduces a high efficiency
AIC1638/1639 step-up controller that can boost
the voltage of single battery cell up to 3.0V, 3.3V,
even to 5.0V. It resolves the problem intend
using only one cell in the devices.
Introduction
AIC1638/1639 is a high efficiency voltage
step-up type control IC using PFM (Pulse
Frequency Modulation) control technology. It
consists of PFM control unit, high-speed error
amplifier, precise reference voltage,
singleswitching transistor for AIC1638, or
push-pull driver output for AIC1639.
Features of AIC1638/1639 : it provides low
quiescent current, very high efficiency power
conversion, and very low gate threshold voltage.
The latter one can guarantee the output voltage
up to the required working level even the input
voltage is started up at 0.8 V.
Therefore, AIC1638/1639 can use every bit of
energy in the cell efficiently to stretch out the
cell’s lifetime. More importantly, it can work with
minimal external elements (such as inductor L,
capacitor C and diode D). It perfectly meets the
smart requirements for the least number of
elements and minimum space (see Figure 1).
Figure 1 AIC1638/1639 Typical Application
Principle
The following simple diagram is used to illustrate
the operating principle of AIC1638/1639.
March 2000
1