TPS79015, TPS79018, TPS79025, TPS79028, TPS79030

ULTRALOW-POWER LOW-NOISE 50-mA

LOW-DROPOUT LINEAR REGULATORS

SLVS299B – SEPTEMBER 2000 – REVISED MAY 2001

13

POST OFFICE BOX 655303

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.

C1

1

µF

BYPASS

OUT

1

3

IN

EN

GND

2

4

5

VI

ESR = 0.2

Ω

VO

4.7

µF

+

TPS790xx†

0.01

µF

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.

MFR.

VALUE

MAX ESR†

SIZE (H

× L × W)†

T494B475K016AS

KEMET

4.7

µF

1.5

Ω

1.9

× 3.5 × 2.8

195D106x0016x2T

SPRAGUE

10

µF

1.5

Ω

1.3

× 7.0 × 2.7

695D106x003562T

SPRAGUE

10

µF

1.3

Ω

2.5

× 7.6 × 2.5

TPSC475K035R0600

AVX

4.7

µF

0.6

Ω

2.6

× 6.0 × 3.2

† Size is in mm. The ESR maximum resistance is in Ohms at 100 kHz and TA = 25°C. Contact the

manufacturer for the minimum ESR values.