TPS51125 Datasheet, PDF (1/33 Pages) Texas Instruments – Dual-Synchronous, Step-Down Controller with Out-of-Audio™ Operation and 100-mA LDOs for Notebook System Power

TPS51125
www.ti.com
SLUS786A – OCTOBER 2007 – REVISED NOVEMBER 2007
Dual-Synchronous, Step-Down Controller with Out-of-Audio™ Operation and 100-mA
LDOs for Notebook System Power
FEATURES
1
•2 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
• Notebook Computers
• I/O Supplies
• System Power Supplies
DESCRIPTION
The TPS51125 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 TPS51125 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
TPS51125 is available in a 24-pin QFN package and
is specified from -40°C to 85°C ambient temperature
range.
3.3V/100mA -
VO2
3.3V/6A
+
VO2_GND -
EN0
-
Typical Application Diagram
SGND
SGND
R6
110kW
R3
13kW
R4
20kW
C0
0.22mF
R2
20kW
R1
30kW
R5
110kW
SGND
VIN
6
5
4
3
2
1
C7
10mF
C8
10mF
PGND
L2
3.3mH
C20
10mF
PGND
Q3
IRF7821
C4
0.1mF
CO2
POSCAP
330mF
Q4
IRF7821
7 VO2
8 VREG3
R8
5.1W
9 VBST2
10 DRVH2
11 LL2
12 DRVL2
TPS51125RGE
(QFN24)
PowerPAD
VO1 24
PGOOD 23
PG R7
100kW VREG5
VBST1 22
DRVH1 21
R9
5.1W
C3
0.1mF
LL1 20
DRVL1 19
VIN
C5
10mF
C6
10mF
+
VIN
5.5 ~ 28V
PGND
Q1
IRF7821 L1
3.3mH
Q2
IRF7821
CO1
POSCAP
330mF
+ VO1
5V/6A
PGND
PGND
SGND
13 14 15 16 17 18
R10
620kW
SGND
VREF
C21
10mF
PGND
PGND
PGND
PGND
VO1
D0_C10
100n
F
C11
100n
F
D1
D2
C12
100n
F
PGND
PGND
C13
100n
F
D4
C14
1uF
PGND
- VO1_GND
VREG5
- 5V/100mA
- 15V/10mA
1
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.
2
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 © 2007, Texas Instruments Incorporated