Datasheet

MCP16331
DS20005308B-page 10  2014 Microchip Technology Inc.
3.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
3.1 Switch Node (SW)
The switch node pin is connected internally to the
NMOS switch, and externally to the SW node
consisting of the inductor and Schottky diode. The
external Schottky diode should be connected close to
the SW node and GND.
3.2 Enable Pin (EN)
The EN pin is a logic-level input used to enable or
disable the device switching, and lower the quiescent
current while disabled. By default the MCP16331 is
enabled through an internal pull-up. To turn off the
device, the EN pin must be pulled low.
3.3 Ground Pin (GND)
The ground or return pin is used for circuit ground
connection. The length of the trace from the input cap
return, output cap return and GND pin should be made
as short as possible to minimize the noise on the GND
pin.
3.4 Feedback Voltage Pin (V
FB
)
The V
FB
pin is used to provide output voltage regulation
by using a resistor divider. The V
FB
voltage will be 0.8V
typical with the output voltage in regulation.
3.5 Boost Pin (BOOST)
The supply for the floating high side driver used to turn
the integrated N-Channel MOSFET on and off is
connected to the boost pin.
3.6 Power Supply Input Voltage Pin
(V
IN
)
Connect the input voltage source to V
IN
. The input
source should be decoupled to GND with a
4.7
µF - 20 µF capacitor, depending on the impedance
of the source and output current. The input capacitor
provides current for the switch node and a stable
voltage source for the internal device power. This
capacitor should be connected as close as possible to
the V
IN
and GND pins.
3.7 Exposed Thermal Pad Pin (EP)
There is an internal electrical connection between the
EP and GND pin for the TDFN package.
TABLE 3-1: PIN FUNCTION TABLE
MCP16331
Symbol Description
TDFN SOT-23
1 6 SW Output switch node, connects to the inductor, freewheeling diode and the
bootstrap capacitor.
2 4 EN Enable pin. There is an internal pull up on the V
IN
. To turn the device off,
connect EN to GND.
3 — NC Not connected
4 — NC Not connected
5 2 GND Ground pin
6 3 V
FB
Output voltage feedback pin. Connect V
FB
to an external resistor divider to set
the output voltage.
7 1 BOOST
Boost voltage that drives the internal NMOS control switch. A bootstrap
capacitor is connected between the BOOST and SW pins.
8 5 V
IN
Input supply voltage pin for power and internal biasing.
9 — EP Exposed Thermal Pad