TS2951_15 Datasheet, PDF (5/9 Pages) Taiwan Semiconductor Company, Ltd – 150mA Ultra Low Dropout Voltage Regulator

BLOCK DIAGRAM
TS2951
Taiwan Semiconductor
APPLICATION INFORMATION
External Capacitors
For the stability of the TS2951 is requires a 1.0µF (0.22µF 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 0.33µF and 0.1µF for
1mA. More output capacitance needed for the 8-pin version at voltage below 5V since it runs the error amplifier at
lower gain. At worst case 3.3≈F or greater must be used for condition of 100mA load at 1.250V output.
The TS2951 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. The TS2951
output voltage is set with minimum load of 1µA and external resistors.
If at the input ofTS2951 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. Instability can occur if
stray capacitor to feedback terminal pin 7 of the TS2951. This could cause more problems when using higher value
of external to set the output voltage. To fix this problem the 100pF capacitor between output and feedback and
increasing output capacitance to 3.3µF.
Document Number: DS_P0000207
5
Version: G15