TPS65251_15 Datasheet, PDF (1/35 Pages) Texas Instruments – TPS65251 4.5-V to 18-V Input, High-Current, Synchronous Step-Down Three Buck Switcher With Integrated FET

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TPS65251
SLVSAA4F – JUNE 2010 – REVISED JULY 2015
TPS65251 4.5-V to 18-V Input, High-Current, Synchronous Step-Down Three Buck
Switcher With Integrated FET
1 Features
•1 Wide Input Supply Voltage Range (4.5 to 18 V)
• 0.8 V, 1% Accuracy Reference
• Continuous Loading: 3 A (Buck 1),
2 A (Buck 2 and 3)
• Maximum Current: 3.5 A (Buck 1),
2.5 A (Buck 2 and 3)
• Adjustable Switching Frequency
300 kHz to 2.2 MHz Set by External Resistor
• Dedicated Enable for Each Buck
• External Synchronization Pin for Oscillator
• External Enable/Sequencing and Soft-Start Pins
• Adjustable Current Limit Set By External Resistor
• Soft-Start Pins
• Current-Mode Control With Simple Compensation
Circuit
• Powergood
• Optional Low-Power Mode Operation for Light
Loads
• VQFN Package, 40-Pin 6 mm × 6 mm RHA
2 Applications
• Set Top Boxes
• Blu-ray DVD
• DVR
• DTV
• Car Audio/Video
• Security Camera
3 Description
The TPS65251 features three synchronous wide
input range high efficiency buck converters. The
converters are designed to simplify its application
while giving the designer the option to optimize their
usage according to the target application.
The converters can operate in 5-, 9-, 12- or 15-V
systems and have integrated power transistors. The
output voltage can be set externally using a resistor
divider to any value between 0.8 V and close to the
input supply. Each converter features enable pin that
allows a delayed start-up for sequencing purposes,
soft-start pin that allows adjustable soft-start time by
choosing the soft-start capacitor, and a current limit
(RLIMx) pin that enables designer to adjust current
limit by selecting an external resistor and optimize the
choice of inductor. The current mode control allows a
simple RC compensation.
The switching frequency of the converters can either
be set with an external resistor connected to ROSC
pin or can be synchronized to an external clock
connected to SYNC pin if needed. The switching
regulators are designed to operate from 300 kHz to
2.2 MHz. 180° out of phase operation between Buck
1 and Buck 2, 3 (Buck 2 and 3 run in phase)
minimizes the input filter requirements.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
TPS65251
VQFN (40)
6.00 mm × 6.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Typical Application Schematic
V2
GPIO or
C1
GND
R22 C24
C21
C2 ^PG
FB2
C25
C26
R23
R20
C23
FB2
GND
VIN
VIN
VIN
C27
4.7 nF
EN2
BST2
VIN2
C20
VIN2
L2
R21
V3
L3
4.7 µH
VIN
GND
LX2
TPS 65251
LX2
L1
V1
LX3
LX1
C31 _C30
VIN3 ^LX3
VIN3
BST3
LX1
VIN1
VIN1
C10
C11
BST1
EN3
EN1
C37
C17
R30
C33
R33
120 kΩ
R13
C13
R10
R1
C36
R31
C34 R32
R12 C14 ^C16
R11
C15
C35
GPIO
or GND
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.