2003-2013 Microchip Technology Inc. DS21762B-page 9
MCP1601
3.0 PIN FUNCTIONS
TABLE 3-1: PIN FUNCTION TABLE
3.1 Input Voltage (V
IN
)
Connect the unregulated input voltage source to V
IN
. If
the input voltage source is located more than several
inches away, or is a battery, a typical input capacitor of
10 µF is recommended.
3.2 Shutdown Input (SHDN)
Connect SHDN to a logic low input to force the device
into a shutdown low quiescent current mode. When in
shutdown, both the P-Channel and N-Channel
switches are turned off, in addition to the internal oscil-
lator and other circuitry. When connected to a logic high
input, the device will operate in the selected mode.
3.3 Feedback Input (FB)
Connect FB to an external resistor divider
to set output
voltage regulation. The feedback pin is typically equal
to 0.8V. See Section 5.0, “Applications Information”, for
details in selecting feedback resistors.
3.4 Analog Ground Return (A
GND
)
Tie all small signal ground returns to A
GND
. (See
Section 5.6, “Printed Circuit Board Layout”, for details).
3.5 Oscillator Synchronization or
PWM/ PFM Select Mode Input
(SYNC/PWM)
Connect an external oscillator to SYNC/PWM to syn-
chronize. With an external oscillator present, the device
is forced into a PWM-only mode of operation. For inter-
nal oscillator operation, the SYNC/PWM pin is tied high
to operate in a forced PWM-only mode and low for a
PWM/PFM mode of operation.
3.6 Output Voltage Sense (V
OUT
)
Connect the output voltage directly to V
OUT
for sensing.
3.7 Power Ground Return (P
GND
)
Connect all large signal ground returns to P
GND
. (See
Section 5.6, “Printed Circuit Board Layout”, for details).
3.8 BUCK Inductor Connection (L
X
)
Connect L
X
directly to the BUCK inductor. This pin car-
ries large signal-level currents and all connections
should be as short and wide as possible. (See
Section 5.6, “Printed Circuit Board Layout”, for details).
Pin Name Function
1V
IN
Input Voltage
2SHDNShutdown Input
3 FB Feedback Input
4A
GND
Analog Ground Return
5 SYNC/
PWM
Oscillator Synchronization or
PWM/ PFM Select Mode Input
6V
OUT
Sensed Output Voltage Input
7P
GND
Power Ground Return
8L
X
BUCK Inductor Output
