Datasheet

 2012 Microchip Technology Inc. DS25160A-page 15
MCP1755/1755S
3.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Tabl e 3-1 and Table 3-2.
3.1 Regulated Output Voltage (V
OUT
)
Connect V
OUT
to the positive side of the load and the
positive side of the output capacitor. The positive side
of the output capacitor should be physically located as
close to the LDO V
OUT
pin as is practical. The current
flowing out of this pin is equal to the DC load current.
3.2 Power Good Output (PWRGD)
The PWRGD output is an open-drain output used to
indicate when the LDO output voltage is within 92%
(typically) of its nominal regulation value. The PWRGD
threshold has a typical hysteresis value of 2%. The
PWRGD output is delayed by 100 µs (typical) from the
time the LDO output is within 92% + 3% (maximum
hysteresis) of the regulated output value on power-up.
This delay time is internally fixed. The PWRGD pin may
be pulled up to V
IN
or V
OUT
. Pulling up to V
OUT
conserves power when the device is in Shutdown
(SHDN
=0V) mode.
3.3 Ground Terminal (GND)
Regulator ground. Tie GND to the negative side of the
output capacitor and also to the negative side of the
input capacitor. Only the LDO bias current flows out of
this pin; there is no high current. The LDO output
regulation is referenced to this pin. Minimize voltage
drops between this pin and the negative side of the
load.
3.4 Shutdown Input (SHDN)
The SHDN input is used to turn the LDO output voltage
on and off. When the SHDN
input is at a logic-high
level, the LDO output voltage is enabled. When the
SHDN input is pulled to a logic-low level, the LDO
output voltage is disabled. When the SHDN
input is
pulled low, the PWRGD output also goes low and the
LDO enters a low quiescent current shutdown state.
TABLE 3-1: MCP1755 PIN FUNCTION TABLE
SOT-223-5 SOT-23-5 2 x 3 DFN Name Function
451V
OUT
Regulated Voltage Output
5 4 2 PWRGD Open Drain Power Good Output
— — 3, 6, 7 NC No connection
3 2 4 GND Ground Terminal
1 3 5 SHDN Shutdown Input
218V
IN
Unregulated Supply Voltage
6 — 9 EP Exposed Pad, Connected to GND
TABLE 3-2: MCP1755S PIN FUNCTION TABLE
SOT-223-3 2 x 3 DFN Name Function
31V
OUT
Regulated Voltage Output
— 2, 3, 5, 6, 7 NC No connection
2 4 GND Ground Terminal
18V
IN
Unregulated Supply Voltage
4 9 EP Exposed Pad, Connected to GND