TPS65251-1_15 Datasheet, PDF (1/39 Pages) Texas Instruments – TPS65251-x 4.5-V to 18-V Input, High Current, Synchronous Step Down Three Buck Switchers With Integrated FET

Product
Folder
Sample &
Buy
Technical
Documents
Tools &
Software
Support &
Community
TPS65251-1, TPS65251-2, TPS65251-3
SLVSC70A – JANUARY 2015 – REVISED JANUARY 2015
TPS65251-x 4.5-V to 18-V Input, High Current, Synchronous Step Down Three Buck
Switchers With Integrated FET
1 Features
•1 Wide Input Supply Voltage Range (4.5 to 18 V)
• Output Range 0.8 V to V_IN – 1 V
• 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
• Adjustable Current Limit Set by External Resistor
• Soft-Start Pins
• Current-Mode Control With Simple Compensation
Circuit
• Power Good
• Automatic PFM/PWM Operation
• 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-x 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 an 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 the 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 the 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.
TPS65251-x features a supervisor circuit that
monitors each converter output. The PGOOD pin is
asserted when sequencing is done, all PG signals are
reported and a selectable end of reset time lapses.
The polarity of the PGOOD signal is active high.
All converters feature an automatic low-power pulse
PFM skipping mode, which improves efficiency during
light loads and standby operation, while ensuring a
very-low output ripple, allowing for a value of less
than 2% at low output voltages.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
TPS65251-1
TPS65251-2
VQFN (40)
6.00 mm × 6.00 mm
TPS65251-3
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
V3
FB3
GND
VIN
VIN
VIN
VIN
GND _TPS65251-X
LX3
VIN3 ^LX3
VIN3
BST3
EN3
EN2
BST2
VIN2
LX2
LX2
LX1
LX1
VIN1
BST1
EN1
VIN2
VIN1
FB2
V2
V1
FB1
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.