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1/12/2005 Rev.2.11

SS8014G

Figure 2. Adjustable Output Using External

Feedback Resistors

Over Current Protection

The SS8014 use a current mirror to monitor the output

current. A small portion of the PMOS output transis-

tor’s current is mirrored onto a resistor such that the

voltage across this resistor is proportional to the output

current. This voltage is compared against the reference

voltage. Once the output current exceeds the limit, the

PMOS output transistor enters constant current mode.

The current is set to 370mA typically.

Over Temperature Protection

To prevent excessive temperatures from occurring, the

SS8014 has a built-in temperature monitoring circuit.

When it detects the temperature is above 150

output transistor is turned off. When the temperature

drops to below 135

this way, the SS8014 is protected against excessive

junction temperatures during operation.

Shutdown Mode

the SS8014 enters shutdown mode. All the analog cir-

cuits are turned off completely, which reduces the cur-

rent consumption to only the leakage current. The

output is disconnected from the input. When the output

has no load at all, the output voltage will be discharged

to ground through the internal resistor voltage divider.

Operating Region and Power Dissipation

Since the SS8014 is a linear regulator, its power dissipa-

maximum power dissipation is given by:

Θ

die and the ambient air,

Θ

of the chosen package to the ambient air. In the case

of a SOT23-5 package, the thermal resistance is typi-

cally 220

The die attachment area of the SS8014’s lead frame is

connected to pin 2, which is the GND pin. Therefore,

the GND pin of SS8014 can carry away the heat of the

SS8014 die very effectively. To improve the power dissi-

pation, connect the GND pin to ground using a large

ground plane near the GND pin.

Capacitor Selection and Regulator Stability

Normally, use a 1µF capacitor on the input and a 1µF

capacitor on the output of the SS8014. Larger input ca-

pacitor values and lower ESR provide better sup-

ply-noise rejection and transient response. A higher-

value input capacitor (10µF) may be necessary if large,

fast transients are anticipated and the device is located

several inches from the power source.

Power-Supply

Rejection

and

Operation

from

Sources Other than Batteries

The SS8014 is designed to deliver low dropout voltages

and low quiescent currents in battery powered sys-

tems. Power-supply rejection is 42dB at low frequen-

cies.

When operating from sources other than batteries, im-

prove supply-noise rejection and transient response by

increasing the values of the input and output capacitors,

and using passive filtering techniques.

Load Transient Considerations

The SS8014 load-transient response graphs show two

components of the output response: a DC shift of the

output voltage due to the different load currents, and

the transient response. Typical overshoot for step

changes in the load current from 0mA to 100mA is

12mV. Increasing the output capacitor's value and de-

creasing its ESR attenuates transient spikes.

Input-Output (Dropout) Voltage

A regulator's minimum input-output voltage differential

(or dropout voltage) determines the lowest usable sup-

ply voltage. In battery-powered systems, this will de-

termine the useful end-of-life battery voltage. Because

the SS8014 use a P-channel MOSFET pass transistor,

by the load current.

IN

OUT

SHDN

ADJ

GND

+

1µF

R1

R2

C

OUT

1µF

OUTPUT

VOLTAGE

470pF

R

L

IN

OUT

SHDN

ADJ

GND

SS8014

+

1µF

R1

R2

C

OUT

1µF

OUTPUT

VOLTAGE

470pF

R

L