SPX116

Rev. 8/21/01

SPX116 Low Dropout Voltage Three Terminal Regulator

©Copyright 2001 Sipex Corporation

4

APPLICATION INFORMATION

The SPX116 requires an output capacitor for device stability.

The value required varies greatly depending upon the

application circuit and other factors. The high frequency

characteristics of electrolytic capacitors depend greatly on the

type and also on the manufacturer. Sometimes only bench

testing is the only means to determine the proper capacitor

type and value. Stability can be obtained with a tantalum or

ceramic capacitor value of 4.7

µF or greater.

Another critical point of electrolytic characteristics is its

performance over temperature. The SPX116 is designed to

operate starting at -40

°C which may not be true in the case of

electrolytic. Higher temperatures generally no problem. The

electrolytic. type in aluminum will freeze around -30

°C. This

could cause an oscillation at output of regulator. At a lower

temperature requirement by many applications the capacitor

should maintain its performance. So as a result, for an

application which regulator junction temperature does not

exceed 25

°C, the output capacitor can be reduced by the

factor of two over the value needed for the entire

temperature range.

In most applications the SPX116 is operating at few

milliamps. In these applications the output capacitance can

be further reduced. For example, when the regulator is

running at 10mA output current the output capacitance

value is half compared to the same regulator that is running

at 100mA. The value decreases with higher output voltages,

since the internal loop gain is reduced.

The worst case occurs at the lower temperature and

maximum operating currents, the entire circuit and the

electrolytic, should be cooled down to the minimum

temperature. The minimum of 0.6 volts required at the input

of regulator above the output to keep the power dissipation

and die heating to its minimum. After the value for the

capacitor has been determined for actual use, the value

should be doubled.