Philips Semiconductors
Multiple voltage regulator with switch
Preliminary specification
TDA3607
Example 1
Regulator 1 is made stable with an electrolytic output
capacitor of 68 µF (ESR = 0.5 Ω), at −30 °C the capacitor
value is decreased to 22 µF and the ESR is increased to
3.5 Ω. The regulator will remain stable at −30 °C.
Solution
Use a tantalum capacitor of 10 µF or a large electrolytic
capacitor. The use tantalum capacitors is recommended to
avoid problems with stability at cold temperatures.
Example 2
Regulator 2 is made stable with a 10 µF electrolytic
capacitor (ESR = 3.3 Ω), at −30 °C the capacitor value is
decreased to 3 µF and the ESR is increased to 23.1 Ω.
The regulator will be unstable at −30 °C (see Fig.7).
handbook, halfp5age
R
(Ω)
4
maximum ESR
3
2
stable region
1
minimum ESR
0.22
1
10
100
C (µF)
MGL138
Fig.6 Curve for selecting the value of output
capacitor for regulator 1.
handbook, halfpage5
R
(Ω)
4
maximum ESR
3
2
stable region
1
minimum ESR
0.22
1
10
100
C (µF)
MGL139
Fig.7 Curve for selecting the value of output
capacitor for regulators 2 and 3.
1997 May 05
10