TPS76130, TPS76132, TPS76133, TPS76138, TPS76150

LOW-POWER 100-mA LOW-DROPOUT LINEAR REGULATORS

SLVS178A – DECEMBER 1998 – REVISED FEBRUARY 1999

9

POST OFFICE BOX 655303

APPLICATION INFORMATION

1

3

5

TPS761xx

IN

EN

OUT

2

CI = 1 µF

Co = 4.7 µF

GND

Figure 17. TPS761xx Typical Application

over current protection

The over current protection circuit forces the TPS761xx into a constant current output mode when the load is

excessive or the output is shorted to ground. Normal operation resumes when the fault condition is removed.

NOTE:

An overload or short circuit may also activate the over temperature protection if the fault

condition persists.

over temperature protection

The thermal protection system shuts the TPS761xx down when the junction temperature exceeds 160

°C. The

device recovers and operates normally when the temperature drops below 150

°C.

input capacitor

A 1-

µF or larger ceramic decoupling capacitor with short leads connected between IN and GND is

recommended. The decoupling capacitor may be omitted if there is a 1

µF or larger electrolytic capacitor

connected between IN and GND and located reasonably close to the TPS761xx. However, the small ceramic

device is desirable even when the larger capacitor is present, if there is a lot of high frequency noise present

in the system.

output capacitor

Like all low dropout regulators, the TPS761xx requires an output capacitor connected between OUT and GND

to stabilize the internal control loop. The minimum recommended capacitance value is 4.7

µF and the ESR

(equivalent series resistance) must be between 0.1

Ω and 10 Ω. 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 Nichicon, meet the ESR requirements stated above. Multilayer ceramic capacitors

should have minimum values of 4.7

µF over the full operating temperature range of the equipment.

enable (EN)

A logic zero on the enable input shuts the TPS761xx off and reduces the supply current to less than 1

the enable input high causes normal operation to resume. If the enable feature is not used, EN should be

connected to IN to keep the regulator on all of the time. The EN input must not be left floating.

reverse current path

The power transistor used in the TPS761xx has an inherent diode connected between IN and OUT as shown

in the functional block diagram. This diode conducts current from the OUT terminal to the IN terminal whenever

IN is lower than OUT by a diode drop. This condition does not damage the TPS761xx provided the current is

limited to 150 mA.