TS2951/A

150mA Ultra Low Dropout Voltage Regulator

3/10

Version: D11

NOTE:

1: Output voltage temperature coefficients defined as the worst case voltage change divided by the total

temperature range.

conditions for the 8-pin versions are feedback tied to 5V, 3.3V & 3V tap output Sense (Vout = 5V, 3.3V & 3V) and

shutdown

≤ 0.8V.

3: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in

output voltage due to heating effects are covered under the specification for thermal regulation.

4: Line regulation for the TS2951 is tested at 85

guaranteed by design to 0.2%.

5: Dropout Voltage is defined as the input to output differential at which the output voltage drops 100mV below its

nominal value measured at 1V differential at very low value of programmed output voltage, the minimum input

supply voltage of 2V (2.3V over temperature) must be taken in to account.

6: Vref

≤ Vout ≤ (Vin-1V), 2.3≤ Vin≤ 30V, 100uA≤ I

L

≤ 100mA, Tj ≤ Tj(max)

.

7: Reference voltage temperature coefficient is defined as the worst case voltage change divided by the total

temperature range.

8: Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the

nominal reference voltage measured at 6V input. To express these thresholds in terms of output voltage change,

multiply by the error amplifier gain= Vout / Vref = (R1+R2) / R2. For example, at a programmed output voltage of

5V, the Error output is guaranteed to go low when the output drops by 95 mV X 5V / 1.250 = 384mV. Thresholds

remain constant as a percent of Vout as Vout is varied with the dropout warning occurring at typically 5% below

nominal, 7.5% guaranteed.

Application Hints

External Capacitors

For the stability of the TS2951/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

recommended since the many aluminum type have electrolytes the freeze at about -30

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. 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 3.3uF or greater must be used for condition of 100mA load at 1.250V output.

The TS2951/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. The

TS2951/A output voltage is set with minimum load of 1uA and external resistors.

If at the input ofTS2951/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. Instability can occur if

stray capacitor to feedback terminal pin 7 of the TS2951/A. 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 3.3uF.