150 mA C-MOS L.D.O. Regulator

LM1185SF

Typical Application Circuit

Detail Description

HTC

−

3 −

1. Output Capacitor

The output capacitor could have an effective series resistance greater than 0.1 Ω and less than .0Ω.

1uF capacitor should be connected from VIN to GND if there is more than 10 inche sofwire between

the regulator and the AC filter capacitor ,or if a battery is used as the power source. Aluminum

electrolytic or tantalum capacitor types can be used. (Since many aluminum electrolytic capacitors

freeze at approximately -30°C, solid tantalums are recommended for applications operating below -25°

C.)

When operating from sources other than batteries,supply-noise rejection and transient response can

be improved by increasing the value of the input and output capacitors and employing passive filtering

techniques.

2. Bypass Input

470pF capacitor connected from the Bypass input to ground reduces noise present on the internal

reference, which in turn significantly reduces output noise. If output noise is not concern, this input

maybe left unconnected. Larger capacitor values maybe used, but results in a longer time period to

rated output voltage when power is initially applied.

3. THERMAL CONSIDERATIONS

3.1 Thermal Shutdown

Integrated thermal protection circuitry shuts the regulator off when die temperature exceeds150°C.

The regulator remains off until the die temperature drops to approxi mately 140°C.

3.2 Power Dissipation

The amount of power the regulator dissipate is primarily a function of input and output voltage, and

output current. The following equation is used to calculate worst case actual power dissipation:

Vin

(To CMOS

Logic or Tie to

Vin if unused)

Gnd

BP

+

1uF

•

SHDN

Vout

+

Battery

Vout

+

470pF

Reference

Bypass

Cap(Optional)

+

1uF

•