TPS51124 Datasheet, PDF (1/22 Pages) Texas Instruments – DUAL SYNCHRONOUS STEP-DOWN CONTROLLER FOR LOW VOLTAGE POWER RAILS

TPS51124
www.ti.com
SLVS616A – NOVEMBER 2005 – REVISED NOVEMBER 2005
DUAL SYNCHRONOUS STEP-DOWN CONTROLLER FOR
LOW VOLTAGE POWER RAILS
FEATURES
• High Efficiency, Low-Power Consumption,
Shutdowns to <1 µA
• Fixed Frequency Emulated On-Time Control,
Frequency Selectable From Three Options
• D-CAP™ Mode Enables Fast Transient
Response
• Auto-Skip Mode
• Less Than 1% Initial Reference Accuracy
• Low Output Ripple
• Wide Input Voltage Range: 3 V to 28 V
• Output Voltage Range: 0.76 V to 5.5 V
• Low-Side R_DS(ON) Loss-less Current Sensing
• Adaptive Gate Drivers With Integrated Boost
Diode
• Internal 1.2-ms Voltage-Servo Soft Start
• Power-Good Signals for Each Channel With
Delay Timer
• Output Discharge During Disable, Fault
APPLICATIONS
• Notebook I/O and Low Voltage System Bus
DESCRIPTION
The TPS51124 is a dual, adaptive on-time D-CAP™
mode synchronous buck controller. The part enables
system designers to cost effectively complete the
suite of notebook power bus regulators with the
absolute lowest external component count and lowest
standby consumption. The fixed frequency emulated
adaptive on-time control supports seamless operation
between PWM mode at heavy load condition and
reduced frequency operation at light load for high
efficiency down to milliampere range. The main
control loop for the TPS51124 uses the D-CAP mode
that optimized for low ESR output capacitors such as
POSCAP or SP-CAP promises fast transient
response with no external compensation. Simple and
separate power good signals for each channel allow
flexibility of power sequencing. The part provides a
convenient and efficient operation with supply input
voltages (V5IN, V5FILT) ranging from 4.5 V to 5.5 V,
conversion voltages (drain voltage for the
synchronous high-side MOSFET) from 3 V to 28 V
and output voltages from 0.76 V to 5.5 V.
The TPS51124 is available in 24-pin QFN package
specified from –40°C to 85°C ambient temperature
range.
Input Voltage
3 V to 28 V
C9
22 µF
R5
R2
R4 _{75 kΩ SGND}
73.2 kΩ
75
kΩ
R1
28.7 kΩ
VO2
1.5 V/10 A
SGND PGND
Power
Good2
C6
10 µF
Q3
IRF7821
L2
1 µH
EN2
C5
0.1 µF
654321
7 PGOOD2
8 EN2
9 VBST2
10 DRVH2
PGOOD1 24
TM
PowerPAD
EN1 23
Power
Good1
EN1
TPS51124RGE
(QFN24)
VBST1 22
C2
0.1 µF
DRVH1 21
Q1
IRF7821
C4
2 x 330 µF
V5IN
4.5 V to 5.5 V
Q4
IRF8113
11 LL2
12 ^DRVL2
LL1 20
DRVL1 ₁₉
Q2
IRF8113
PGND
13 14 15 16 17 18
R6
6.8 kΩ
R7 ^R3
3.3Ω ^6.8
kΩ
C7
4.7 μF
C8
1 μF
PGND
PGND
SGND
C3
L1 ^{10 µF}
1 µH
VO1
1.05 V/10 A
C1
2 x 330 µF
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.
D-CAP, PowerPAD are trademarks of Texas Instruments.
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 © 2005, Texas Instruments Incorporated