AP6503 Datasheet, PDF (2/13 Pages) Diodes Incorporated – 340kHz 23V 3A SYNCHRONOUS DC/DC BUCK CONVERTER

AP6503
340kHz 23V 3A SYNCHRONOUS DC/DC BUCK CONVERTER
Pin Descriptions
Pin #
1
Name
BS
2
IN
3
SW
4
GND
5
FB
6
COMP
7
EN
8
SS
Description
High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET
switch. Connect a 0.01µF or greater capacitor from SW to BS to power the high side switch.
Power Input. IN supplies the power to the IC, as well as the step-down converter switches.
Drive IN with a 4.75V to 24V power source. Bypass IN to GND with a suitably large capacitor
to eliminate noise on the input to the IC. See Input Capacitor.
Power Switching Output. SW is the switching node that supplies power to the output. Connect
the output LC filter from SW to the output load. Note that a capacitor is required from SW to
BS to power the high-side switch.
Ground (Connect the exposed pad to Pin 4).
Feedback Input. FB senses the output voltage and regulates it. Drive FB with a resistive
voltage divider connected to it from the output voltage. The feedback threshold is 0.925V. See
Setting the Output Voltage.
Compensation Node. COMP is used to compensate the regulation control loop. Connect a
series RC network from COMP to GND. In some cases, an additional capacitor from COMP to
GND is required. See Compensation Components.
Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on
the regulator; low to turn it off. Attach to IN with a 100kΩ pull up resistor for automatic startup.
Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor from SS to GND
to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 15ms. To disable the
soft-start feature, leave SS floating.
Functional Block Diagram
Figure 3. Functional Block Diagram
AP6503
Document number: DS35077 Rev. 1 - 2
2 of 13
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September 2011
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