TPS79015, TPS79018, TPS79025, TPS79028, TPS79030
ULTRALOW-POWER LOW-NOISE 50-mA
LOW-DROPOUT LINEAR REGULATORS
SLVS299B – SEPTEMBER 2000 – REVISED MAY 2001
APPLICATION INFORMATION
The TPS790xx family of low-dropout (LDO) regulators have been optimized for use in battery-operated
equipment. They feature extremely low dropout voltages, low quiescent current (17 µA typically), and enable
inputs to reduce supply currents to less than 1 µA when the regulators are turned off.
A typical application circuit is shown in Figure 26.
†
TPS790xx
1
3
V
IN
I
4
5
BYPASS
OUT
V
O
C1
1 µF
0.01 µF
EN
+
4.7 µF
GND
2
ESR = 0.2 Ω
Figure 26. Typical Application Circuit
external capacitor requirements
Although not required, a 0.047-µF or larger ceramic input bypass capacitor, connected between IN and GND
and located close to the TPS790xx, is recommended to improve transient response and noise rejection. A
higher-value electrolytic input capacitor may be necessary if large, fast-rise-time load transients are anticipated
and the device is located several inches from the power source.
Like all low dropout regulators, the TPS790xx requires an output capacitor connected between OUT and GND
to stabilize the internal control loop. The minimum recommended capacitance is 4.7 µF. The ESR (equivalent
series resistance) of the capacitor should be between 0.2 Ω and 10 Ω to ensure stability. Capacitor values larger
than 4.7 µF are acceptable, and allow the use of smaller ESR values. Capacitances less than 4.7 µF are not
recommended because they require careful selection of ESR to ensure stability. Solid tantalum electrolytic,
aluminum electrolytic, and multilayer ceramic capacitors are all suitable, provided they meet the requirements
described above. Most of the commercially available 4.7 µF surface-mount solid tantalum capacitors, including
devices from Sprague, Kemet, and Nichico, meet the ESR requirements stated above. Multilayer ceramic
capacitors may have very small equivalent series resistances and may thus require the addition of a low value
series resistor to ensure stability.
CAPACITOR SELECTION
†
†
PART NO.
T494B475K016AS
195D106x0016x2T
695D106x003562T
TPSC475K035R0600
MFR.
KEMET
SPRAGUE
SPRAGUE
AVX
VALUE
4.7 µF
10 µF
MAX ESR
SIZE (H × L × W)
1.9 × 3.5 × 2.8
1.3 × 7.0 × 2.7
2.5 × 7.6 × 2.5
2.6 × 6.0 × 3.2
1.5 Ω
1.5 Ω
1.3 Ω
0.6 Ω
10 µF
4.7 µF
†
Size is in mm. The ESR maximum resistance is in Ohms at 100 kHz and T = 25°C. Contact the
manufacturer for the minimum ESR values.
A
13
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TI [ TEXAS INSTRUMENTS ]
