LTC3388-1_15 Datasheet, PDF (9/20 Pages) Linear Technology – 20V High Efficiency Nanopower Step-Down Regulator

LTC3388-1/LTC3388-3
PIN FUNCTIONS
EN (Pin 1): Enable Input. Logic level input referenced to
V_IN2. A logic high on EN will enable the buck converter.
Driving EN to V_IN2 will result in no additional quiescent
current on V_IN. However, if EN is driven near V_IH or V_IL
40nA of additional quiescent current can appear on V_IN.
STBY (Pin 2): Standby Input. Logic level input referenced
to V_IN2. A logic high on STBY will place the part in standby
mode. Driving STBY to V_IN2 will result in no additional
quiescent current on V_IN. However, if STBY is driven near
V_IH or V_IL 40nA of additional quiescent current can ap-
pear on V_IN.
CAP (Pin 3): Internal rail referenced to V_IN to serve as gate
drive for buck PMOS switch. A 1μF capacitor should be
connected between CAP and V_IN. This pin is not intended
for use as an external system rail.
V_IN (Pin 4): Input Voltage. A 2.2μF or larger capacitor
should be connected from V_IN to GND.
SW (Pin 5): Switch Pin for the Buck Switching Regulator.
A 22μH or larger inductor should be connected from SW
to V_OUT.
V_OUT (Pin 6): Sense pin used to monitor the output volt-
age and adjust it through internal feedback.
V_IN2 (Pin 7): Internal low voltage rail to serve as gate drive
for buck NMOS switch. Also serves as a logic high rail for
output voltage select bits D0 and D1. A 4.7μF capacitor
should be connected from V_IN2 to GND. This pin is not
intended for use as an external system rail.
D1 (Pin 8): Output Voltage Select Bit. D1 should be tied
high to V_IN2 or low to GND to select desired V_OUT (see
Table 1).
D0 (Pin 9): Output Voltage Select Bit. D0 should be tied
high to V_IN2 or low to GND to select desired V_OUT (see
Table 1).
PGOOD (Pin 10): Power Good Open-Drain NMOS Output.
The PGOOD pin is Hi-Z when V_OUT is above 92% of the
target value.
GND (Exposed Pad Pin 11): Ground. The exposed pad
should be connected to a continuous ground plane on the
second layer of the printed circuit board by several vias
directly under the LTC3388-1/LTC3388-3.
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