XR79120 Datasheet, PDF (1/19 Pages) Exar Corporation – 22V, 20A Synchronous Step Down COT Power Module

XR79120
22V, 20A Synchronous Step Down COT Power Module
General Description
The XR79120 is a 20A synchronous step-down Power Module for point-of
load supplies. A wide 4.5V to 22V input voltage range allows for single
supply operation from industry standard 5V, 12V, and 19.6V rails.
With a proprietary emulated current mode Constant On-Time (COT) con-
trol scheme, the XR79120 provides extremely fast line and load transient
response using ceramic output capacitors. It requires no loop compensa-
tion hence simplifying circuit implementation and reducing overall compo-
nent count. The control loop also provides 0.12% load and 0.17% line
regulation and maintains constant operating frequency. A selectable
power saving mode allows the user to operate in discontinuous mode
(DCM) at light current loads thereby significantly increasing the converter
efficiency. With a 93% peak efficiency and 84% for loads as low as
100mA, the XR79120 is suitable for applications where low power losses
are important.
A host of protection features, including over-current, over-temperature,
short-circuit and UVLO, help achieve safe operation under abnormal
operating conditions.
The XR79120 is available in a RoHS compliant, green/halogen free
space-saving 74-pin 12x14x4mm QFN package. With integrated control-
ler, drivers, bootstrap diode and capacitor, MOSFETs, inductor, CIN and
COUT, this solution allows the smallest possible 20A POL design.
FEATURES
 Controller, drivers, bootstrap diode and capaci-
tor, MOSFETs, Inductor, CIN and COUT integrated
in one package
 20A Step Down Module
 Wide 4.5V to 22V Input Voltage Range
 >0.6V Adjustable Output Voltage
 Proprietary Constant On-Time Control
 No Loop Compensation Required
 Stable Ceramic Output Capacitor Operation
 Programmable 200ns to 2μs On-Time
 Constant 400kHz to 600kHz Frequency
 Selectable CCM or CCM/DCM
 CCM/DCM for high efficiency at light-load
 CCM for constant frequency at light-load
 Programmable Hiccup Current Limit with Ther-
mal Compensation
 Precision Enable and Power Good flag
 Programmable Soft-start
 74-pin 12x14x4mm QFN package
APPLICATIONS
 Networking and Communications
 Fast Transient Point-of-Loads
 Industrial and Medical Equipment
 Embedded High Power FPGA
Ordering Information – back page
Typical Application
VIN
Enable/Mode
Power Good
CIN
R
VIN
PVIN
EN/MODE
PGOOD
VOUT
VCC XR79120 SW
RLIM
SS
ILIM
CVCC
CSS
TON
RON
AGND
FB
PGND
CFF
R1
R2
VOUT
COUT
Line Regulation
1.820
1.815
1.810
1.805
1.800
1.795
1.790
1.785
1.780
4 6 8 10 12 14 16 18 20 22
V_IN (V)
© 2014 Exar Corporation
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exar.com/XR79120
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