SLUS976E – SEPTEMBER 2009 – REVISED MARCH 2012
Dual-Synchronous, Step-Down Controller with Out-of-Audio™ Operation
and 100-mA LDOs for Notebook System Power
Check for Samples:
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FEATURES
Wide Input Voltage Range: 5.5 V to 28 V
Output Voltage Range: 2 V to 5.5 V
Built-in 100-mA 5-V/3.3-V LDO with Switches
Built-in 1% 2-V Reference Output
With/Without Out-of-Audio™ Mode Selectable
Light Load and PWM only Operation
Internal 1.6-ms Voltage Servo Softstart
Adaptive On-Time Control Architecture with
Four Selectable Frequency Setting
4500 ppm/°C R
DS(on)
Current Sensing
Built-In Output Discharge
Power Good Output
Built-in OVP/UVP/OCP
Thermal Shutdown (Non-latch)
QFN24 (RGE)
APPLICATIONS
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Notebook Computers
I/O Supplies
System Power Supplies
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DESCRIPTION
The TPS51125A is a cost effective, dual-synchronous
buck controller targeted for notebook system power
supply solutions. It provides 5-V and 3.3-V LDOs and
requires few external components. The 270-kHz
VCLK output can be used to drive an external charge
pump, generating gate drive voltage for the load
switches without reducing the main converter’s
efficiency. The TPS51125A supports high efficiency,
fast transient response and provides a combined
power-good signal. Out-of-Audio™ mode light-load
operation enables low acoustic noise at much higher
efficiency than conventional forced PWM operation.
Adaptive on-time D-CAP™ control provides
convenient and efficient operation. The part operates
with supply input voltages ranging from 5.5 V to 28 V
and supports output voltages from 2 V to 5.5 V. The
TPS51125A is available in a 24-pin QFN package
and is specified from -40°C to 85°C ambient
temperature range.
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Table 1. Differences between the TPS51125 and TPS51125A
TPS51125
VREG5: at least 33 µF
LDO Output Capacitance Requirement
VREG3: at most 10 µF
(1 µF acceptable at no load)
VREF: 0.22 µF to 1 µF
TPS51125A
VREG5: 10 µF or larger (X5R or X7R)
VREG3: 10 µF or larger (X5R or X7R)
(1 µF acceptable at no load)
VREF: 0.22 µF to 1 µF (X5R or X7R)
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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.
Out-of-Audio, D-CAP are trademarks of Texas Instruments.
Copyright © 2009–2012, Texas Instruments Incorporated
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.
TI [ TEXAS INSTRUMENTS ]
