MIC2203 Datasheet, PDF (6/13 Pages) Micrel Semiconductor – High Efficiency 1MHz Synchronous Buck Regulator

Micrel, Inc.
Functional Description
V_IN
V provides power to the output and to the internal
IN
bias supply. The supply voltage range is from 2.3V
to 5.5V. A minimum 1µF ceramic capacitor is
recommended for bypassing the input supply.
Enable
The enable pin provides a logic level control of the
output. In the off state, supply current of the device
is greatly reduced (typically <1µA). Also, in the off
state, the output drive is placed in a “tri-stated”
condition, where both the high side P-Channel
MOSFET and the low-side N-Channel are in an off
or non-conducting state. Do not drive the enable pin
above the supply voltage.
SYNC_IN
SYNC_IN pin enables the ability to change the
fundamental switching frequency. The SYNC_IN
frequency has a minimum frequency of 800KHz and
a maximum sync frequency of 1.2MHz. Careful
attention should be paid to not driving the SYNC_IN
pin greater than the supply voltage. Although this will
not damage the device, it can cause improper
operation.
MIC2203
SYNC_OUT
SYNC_OUT is an open collector output that
provides a signal equal to the internal oscillator
frequency. This creates the ability for multiple
MIC2203s to be connected together in a master-
slave configuration for frequency matching of the
converters. A typical 10kΩ resistor is recommended
for the pull-up resistor.
Bias
The bias supply is an internal 2.3V linear regulator
that supplies the internal biasing voltage to the
MIC2203. A 10nF ceramic capacitor is required on
this pin for bypassing. Do not use the bias pin as a
supply. The bias pin was designed to supply internal
power only.
Feedback
The feedback pin provides the control path to control
the output. A resistor divider connecting the
feedback to the output is used to adjust the desired
output voltage. Refer to the feedback section in the
“Applications Information” for more detail.
December 2004
6
M9999-120604
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