Datasheet LTC3621, LTC3621-2 (Analog Devices) - 7

LTC3621/LTC3621-2
pin FuncTions (DFN/MSOP) SW (Pin 1/Pin 1):
Switch Node Connection to the Inductor
INTVCC (Pin 5/Pin 6):
Low Dropout Regulator. Bypass with of the Step-Down Regulator. at least 1µF to Ground.
VIN (Pin 2/Pin 2):
Input Voltage of the Step-Down Regulator.
MODE/SYNC (Pin 6/Pin 7):
Burst Mode Select and External
RUN (Pin 3/Pin 3):
Logic Controlled RUN Input. Do not Clock Synchronization of the Step-Down Regulator. Tie leave this pin floating. Logic high activates the step-down MODE/SYNC to INTVCC for Burst Mode operation with a regulator. 400mA peak current clamp, tie MODE/SYNC to GND for pulse skipping operation, and tie MODE/SYNC to a volt-
FB (Pin 4/Pin 5):
Feedback Input to the Error Amplifier age between 1V and VINTVCC – 1.2V for forced continuous of the Step-Down Regulator. Connect a resistor divider mode. Furthermore, connecting MODE/SYNC to an external tap to this pin. The output voltage can be adjusted from clock will sync the system clock to the external clock and 0.6V to VIN by: put the part in forced continuous mode. VOUT = 0.6V • [1 + (R2/R1)]
GND (Exposed Pad Pin 7/Pin 9):
Ground Backplane for For Fixed V Power and Signal Ground. Must be soldered to PCB ground. OUT options, connect the FB pin directly to VOUT.
PGOOD (Pin 4, MSOP Package Only):
V
SGND (Pin 8, MSOP Package Only):
Signal Ground. OUT within Regu- lation Indicator.
block DiagraM
VIN 0.8ms SLOPE SOFT-START COMPENSATION ERROR + AMPLIFIER BURST MAIN AMPLIFIER I-COMPARATOR ITH 0.6V + + + FB – – – V FIXED VOUT MODE/SYNC CLK OSCILLATOR OVERCURRENT COMPARATOR INTV VIN – 5V CC LDO BUCK + SW LOGIC AND RUN GATE DRIVE – INTVCC PGOOD + – REVERSE MS8E PACKAGE ONLY COMPARATOR GND 3621 BD 3621fc For more information www.linear.com/LTC3621 7 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts