TS2950_11 Datasheet, PDF (3/7 Pages) Taiwan Semiconductor Company, Ltd – 150mA Ultra Low Dropout Voltage Regulator

TS2950/A
150mA Ultra Low Dropout Voltage Regulator
Application Hints
External Capacitors
For the stability of the TS2950/A is requires a 1.0uF(0.22uF is recommended for 3.0V & 3.3V) or greater capacitor
between output and ground. Oscillation could occur without this capacitor. The tantalum or aluminum electrolytic
works fine; could use the film type work but are not cost efficient. For the operation of below -25 ^oC solid tantalum is
recommended since the many aluminum type have electrolytes the freeze at about -30 ^oC. The ESR of about 5Ω or
less and resonant frequency above 500KHz are most important parameter in the value of Capacitor. The
Capacitors value can be increased without any limit. At lower values of output current, less output capacitance is
required for stability. For the currents below 10mA the value of capacitor can be reduce to 0.33uF and 0.1uF for
1mA.
The TS2950/A is not like other low dropout regulators will remain stable and regulation with no load in addition to
the internal voltage divider. This feature very important in application, it is like CMOS RAM keep-alive.
If at the input of TS2950/A connected to battery or between AC filter capacitor and input is 10 inches wire then 1uF
tantalum or aluminum electrolytic capacitor should be connected between input and ground. This could cause more
problems when using higher value of external to set the output voltage. To fix this problem increasing output
capacitance to 3.3uF.
Reducing Output Noise
It could be an advantage to reduce the AC noise present at the output. One method is to reduce the regulator
bandwidth by increasing the value of the output capacitor. This is the only method that noise could reduce on the
TS2950/A, but is relatively inefficient, as increasing capacitor from 1uF to 220uF only decreases the noise from
430uV to 160uVrms for a 100KHz bandwidth at 5V output.
the output capacitor must be increased to 3.3uF to maintain stability. These change the output noise from
430uV/rms for a 100 kHz bandwidth 5V, 3.3V & 3V output.
Block Diagram and Typical Applications Circuit
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Version: D11