XR79120 Datasheet, PDF (6/19 Pages) Exar Corporation – 22V, 20A Synchronous Step Down COT Power Module

XR79120
Pin Assignments
Pin No.
1
2
Pin Name
PGOOD
FB
3, 71, 72,
AGND PAD
4
5
AGND
VIN
VCC
6, 7, GL PAD GL
8
PGND
13-26, 57,
58, PGND
PADS
PGND
9-12, 27-32, SW
SW PAD
33-56,
VOUT
VOUT PADS
59-66, PVIN PVIN
PAD
67, 68, BST BST
PAD
69
ILIM
70
EN/MODE
73
TON
74
SS
Type
OD, O
A
A
PWR
PWR
O
PWR
PWR
Description
Power-good output. This open-drain output is pulled low when V_OUT is outside the regulation.
Feedback input to feedback comparator. Connect with a set of resistors to VOUT and AGND in
order to program VOUT.
Analog ground. Control circuitry of the IC is referenced to this pin. Should be connected to
PVIN at a single point.
Controller supply input. Provides power to internal LDO. Connect to PVIN.
The output of LDO. Bypass with a 4.7uF capacitor to AGND. For operation from a 5V_IN rail,
VCC should be tied to VIN.
Driver output for Low-side N-channel synchronous MOSFET. It is internally connected to the
gate of the MOSFET. Leave these pins floating.
Controller low-side driver ground. Connect with a short trace to closest PGND pins or PGND
pad.
Ground of the power stage. Should be connected to the system’s power ground plane.
PWR
PWR
Switching node. It is internally connected. Use thermal vias and/or sufficient PCB land area in
order to heatsink the low-side FET and the inductor.
Output of the power stage. Place the output filter capacitors as close as possible to these pins.
PWR
Power stage input voltage. Place the input filter capacitors as close as possible to these pins.
A
Controller high-side driver supply pin. It is internally connected to SW via a 0.1uF bootstrap
capacitor. Leave these pins floating.
A
Over-current protection programming. Connect with a resistor to SW pins.
I
Precision enable pin. Pulling this pin above 1.9V will turn the Module on and it will operate in
Forced CCM. If the voltage is raised above 3.0V, then the Module will operate in DCM or CCM
depending on load.
A
Constant on-time programming pin. Connect with a resistor to AGND.
A
Soft-start pin. Connect an external capacitor between SS and AGND to program the soft-start
rate based on the 10uA internal source current.
Type: A = Analog, I = Input, O = Output, I/O = Input/Output, PWR = Power, OD = Open-Drain
© 2014 Exar Corporation
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exar.com/XR79120
Rev 1A