Datasheet

MCP1252/3
DS21752B-page 8  2002-2013 Microchip Technology Inc.
3.0 PIN FUNCTIONS
TABLE 3-1: PIN FUNCTION TABLE
3.1 Open-Drain Power Good Output
(PGOOD)
PGOOD is a high-impedance when the output voltage
is in regulation. A logic-low is asserted when the output
falls 7% (typical) below the nominal value. The PGOOD
output remains low until V
OUT
is within 3% (typical) of
its nominal value. On start-up, this pin indicates when
the output voltage reaches its final value. PGOOD is
high-impedance when SHDN
is low.
3.2 Regulated Output Voltage (V
OUT
)
Bypass to GND with a filter capacitor.
3.3 Power Supply Input (V
IN
)
It is recommended that V
IN
be tied to a ceramic bypass
capacitor.
3.4 Ground (GND)
It is recommended that the ground pin be tied to a
ground plane for best performance.
3.5 Flying Capacitor Negative
Terminal (C-)
The charge pump capacitor (flying capacitor) is used to
transfer charge from the input supply to the regulated
output.
It is recommended that a low ESR (equivalent series
resistance) capacitor be used.
3.6 Flying Capacitor Positive Terminal
(C+)
The charge pump capacitor (flying capacitor) is used to
transfer charge from the input supply to the regulated
output.
Proper orientation is imperative when using a polarized
capacitor.
3.7 Shutdown Input (SHDN)
A logic-low signal applied to SHDN disables the device.
A logic-high signal applied to this pin allows normal
operation.
3.8 Select (SELECT) Input or
Feedback (FB) Input
MCP1252-33X50, MCP1253-33X50:
SELECT: Select Input Pin.
Connect SELECT to V
IN
for 3.3V fixed output. Connect
SELECT to GND for a 5.0V fixed output.
MCP1252-ADJ, MCP1253-ADJ:
FB: Feedback Pin.
A resistor divider connected to this pin determines the
adjustable V
OUT
value (1.5V to 5.5V).
Pin
No.
Name Function
1 PGOOD
Open-Drain Power GOOD Output
2V
OUT
Regulated Output Voltage
3V
IN
Power Supply Input
4GND
Ground Terminal
5C-
Flying Capacitor Negative Terminal
6C+
Flying Capacitor Positive Terminal
7 SHDN
Shutdown Mode, Active-Low Input
8 SELECT
Output Voltage Select Pin.
(MCP1252-33X50, MCP1253-33X50)
FB
Feedback Input Pin for Adjustable Output
(MCP1252-ADJ, MCP1253-ADJ)