TPS54821
www.ti.com
SLVSB14 –OCTOBER 2011
4.5 V to 17 V Input, 8 A Synchronous Step Down SWIFT™ Converter With Hiccup
Check for Samples: TPS54821
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FEATURES
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Integrated 26 mΩ / 19 mΩ MOSFETs
Split Power Rail: 1.6 V to 17 V on PVIN
200 kHz to 1.6 MHz Switching Frequency
Synchronizes to External Clock
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Adjustable Input Undervoltage Lockout
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Software Tools Available
For SWIFT™ Documentation visit
http://www.ti.com/swift
0.6V ±1% Voltage Reference Over Temperature
Low 2 µA Shutdown Quiescent Current
Monotonic Start-Up into Pre-biased Outputs
APPLICATIONS
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Digital TV Power Supplies
Set Top Boxes
–40°C to 125°C Operating Junction
Temperature Range
Blu-ray DVDs
Home Terminals
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Adjustable Slow Start/Power Sequencing
High Performance Point of Load Regulation
Power Good Output Monitor for Undervoltage
and Overvoltage
DESCRIPTION
The TPS54821 in thermally enhanced 3.5 mm x 3.5 mm QFN package is a full featured 17 V, 8 A synchronous
step down converter which is optimized for small designs through high efficiency and integrating the high-side
and low-side MOSFETs. Further space savings are achieved through current mode control, which reduces
component count, and by selecting a high switching frequency, reducing the inductor's footprint.
The output voltage startup ramp is controlled by the SS/TR pin which allows operation as either a stand alone
power supply or in tracking situations. Power sequencing is also possible by correctly configuring the enable and
the open drain power good pins.
Cycle by cycle current limiting on the high-side FET protects the device in overload situations and is enhanced
by a low-side sourcing current limit which prevents current runaway. There is also a low-side sinking current limit
which turns off the low-side MOSFET to prevent excessive reverse current. Hiccup protection will be triggered if
the overcurrent condition has persisted for longer than the preset time. Thermal hiccup protection disables the
device when the die temperature exceeds the thermal shutdown temperature and enables the part again after
the built-in thermal shutdown hiccup time.
WHITE SPACE
SIMPLIFIED SCHEMATIC
EFFICIENCY, VOUT = 3.3 V, FSW = 480 kHz
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90
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PVIN
VIN
VIN
Cboot
TPS54821
BOOT
Cin
VOUT
Lo
EN
PH
Co
PWRGD
R1
VSENSE
SS/TR
R2
RT/CLK
COMP
GND
VIN = 8 V
VIN = 12 V
VIN = 17 V
R3
C1
Exposed
Thermal
Pad
Css
Rrt C2
0
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Output Current (A)
G001
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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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SWIFT is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2011, Texas Instruments Incorporated