TPS79428_15 Datasheet, PDF (1/23 Pages) Texas Instruments – ULTRALOW-NOISE, HIGH-PSRR, FAST, RF, 250-mA LOW-DROPOUT LINEAR REGULATORS

TPS794xx
www.ti.com
SLVS349E – NOVEMBER 2001 – REVISED DECEMBER 2005
ULTRALOW-NOISE, HIGH-PSRR, FAST, RF, 250-mA
LOW-DROPOUT LINEAR REGULATORS
FEATURES
• 250-mA Low-Dropout Regulator With Enable
• Available in Fixed and Adjustable (1.2 V to
5.5 V) Versions
• High PSRR (60 dB at 10 kHz)
• Ultralow Noise (32 µVrms, TPS79428)
• Fast Start-Up Time (50 µs)
• Stable With a 2.2-µF Ceramic Capacitor
• Excellent Load/Line Transient Response
• Very Low Dropout Voltage (155 mV at Full
Load)
• Available in MSOP-8 and SOT223-6 Packages
APPLICATIONS
• RF: VCOs, Receivers, ADCs
• Audio
• Bluetooth™, Wireless LAN
• Cellular and Cordless Telephones
• Handheld Organizers, PDAs
DESCRIPTION
The TPS794xx family of low-dropout (LDO) linear
voltage regulators features high power-supply
rejection ratio (PSRR), ultralow-noise, fast start-up,
and excellent line and load transient responses in
small outline, MSOP-8 PowerPAD™ and SOT223-6
packages. Each device in the family is stable with a
small 2.2-µF ceramic capacitor on the output. The
family uses an advanced, proprietary BiCMOS
fabrication process to yield extremely low dropout
voltages (for example, 155 mV at 250 mA). Each
device achieves fast start-up times (approximately
50 µs with a 0.001-µF bypass capacitor) while
consuming low quiescent current (170 µA typical).
Moreover, when the device is placed in standby
mode, the supply current is reduced to less than
1 µA. The TPS79428 exhibits approximately
32 µV_RMS of output voltage noise at 2.8 V output with
a 0.1-µF bypass capacitor. Applications with analog
components that are noise-sensitive, such as
portable RF electronics, benefit from the high PSRR
and low noise features as well as the fast response
time.
DGN PACKAGE
MSOP-8 PowerPADt
(TOP VIEW)
OUT
1
NC
2
FB
3
NR
4
8
IN
7
NC
6
EN
5
GND
NC − No internal connection
DCQ PACKAGE
SOT223-6
(TOP VIEW)
EN
1
IN
2
GND
3
OUT
4
NR/FB
5
6
GND
TPS79433
RIPPLE REJECTION
vs
FREQUENCY
90
80
I_OUT = 10 mA
70
I_OUT = 250 mA
60
50
40
30
V_IN = 4.3 V,
20
V_OUT = 3.3 V,
C_IN = 1 µF,
10
C_OUT = 10 µF,
C_NR = 0.01 µF
0
10 100 1 k 10 k 100 k 1 M 10 M
Frequency (Hz)
TPS79428
OUTPUT SPECTRAL NOISE DENSITY
vs
FREQUENCY
0.35
0.30
C_OUT = 2.2 µF,
C_NR = 0.1 µF,
V_IN = 3.8 V
0.25
0.20
I_OUT = 250 mA
0.15
0.10
0.05
0
100
I_OUT = 1 mA
1000
10000
Frequency (Hz)
100000
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.
PowerPAD is a trademark of Texas Instruments.
Bluetooth is a trademark of Bluetooth SIG, Inc.
All other trademarks are the property of their respective owners.
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 © 2001–2005, Texas Instruments Incorporated