Datasheet LTC3107 (Analog Devices) - 7

LTC3107
pin FuncTions VAUX (Pin 1):
Output of the Internal Rectifier Circuit and IC and the loads on VOUT and VLDO. A ceramic decoupling VCC for the IC. Bypass VAUX with 10µF of capacitance. capacitor with a minimum value of 10µF is recommended An active shunt regulator clamps VAUX to 4.3V (typical). from VBAT to GND.
VSTORE (Pin 2):
Output for the Optional Energy Storage
VLDO (Pin 5):
Output of the 2.2V LDO, which is powered Capacitor. A large capacitor may be connected from this from the higher of VOUT or VAUX. Connect a 2.2µF or pin to GND to store excess harvested energy, further ex- larger ceramic capacitor from VLDO to GND. If not used, tending battery life in the event of an increase in load. It this pin should be tied to VAUX. will be charged up to the maximum VAUX clamp voltage.
GND (Pin 6 and Exposed Pad Pin 11):
Ground Pin for the If not used, this pin should be left open or tied to VAUX. IC. The exposed pad must be soldered to the PCB ground
VOUT (Pin 3):
Main Output of the Converter. When plane. It serves as a ground connection, and as a means harvested energy is available, the voltage at this pin is of conducting heat away from the die. regulated to 30mV below the voltage on the VBAT pin. If
BAT_OFF (Pin 7):
Battery Off Output. This pin is an indicator no (or insufficient) harvested energy is available to power of when the battery is in use. A logic low indicates that the the load, VOUT will be regulated to a voltage about 230mV battery is being used to assist in regulating V below the voltage at V OUT. The pin BAT. A large decoupling capacitor is will go high when V usually required from V OUT is in regulation and the battery is OUT to GND, to allow the output not being used. It is not designed to source any current. to ride-through short duration load transients without It has an internal 1M pull-up resistor to V drawing current from the battery. A minimum capacitance OUT. value of 47µF is recommended for all applications. See
C1 (Pin 8):
Input to the Charge Pump and Rectifier Circuit. the Applications Information section for details on sizing Connect a capacitor from this pin to the secondary winding the capacitor. of the step-up transformer.
VBAT (Pin 4):
Primary Battery Input. This pin must be
C2 (Pin 9):
Input to the N-Channel Gate Drive Circuit. Con- connected to a primary battery. This input will be used nect a capacitor from this pin to the secondary winding during start-up to bring VOUT into regulation (as well as of the step-up transformer. VAUX and VLDO). After start-up, this input is used only as
SW (Pin 10):
Drain of the Internal N-Channel Switch. Con- a reference voltage for VOUT, unless there is insufficient nect this pin to the primary winding of the transformer. harvested power available, in which case it will power the 3107f For more information www.linear.com/LTC3107 7 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts