TDA3608THQ Ver la hoja de datos (PDF) - Philips Electronics
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TDA3608THQ Datasheet PDF : 22 Pages
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Philips Semiconductors
Multiple voltage regulators with switch
Product specification
TDA3608Q; TDA3608TH
Application information
NOISE
The noise on the supply line depends on the value of the
supply capacitor and is caused by a current noise (the
output noise of the regulators is translated into a current
noise by means of the output capacitors). Table 1 shows
the noise figure with the corresponding output capacitor Co
for each regulator. The noise is minimal when a high
frequency capacitor of 220 nF in parallel with an
electrolytic capacitor of 100 µF is connected directly to
pins VP and GND.
Table 1 Noise figure; note 1
NOISE FIGURE (µV)
REGULATOR
Co = 10 µF Co = 47 µF Co = 100 µF
1
225
150
135
2
225
150
135
3
255
200
180
Note
1. Measured at a bandwidth of 200 kHz.
STABILITY
The regulators are made stable with the externally
connected output capacitors. The output capacitors can be
selected using the graphs of Figs 13 and 14. When an
electrolytic capacitor is used, the temperature behaviour of
this output capacitor can cause oscillations at low
temperature. The next two examples show how an output
capacitor value is selected.
Example 1
The regulator 1 is made stable with an electrolytic output
capacitor of 220 µF with ESR = 0.15 Ω. At Tamb = −30 °C
the capacitor value is decreased to 73 µF and the ESR is
increased to 1.1 Ω. The regulator remains stable at
Tamb = −30 °C (see Fig.13).
Example 2
The regulator 2 is made stable with an electrolytic
capacitor of 10 µF with ESR = 3 Ω. At Tamb = −30 °C the
capacitor value is decreased to 3 µF and the ESR is
increased to 23.1 Ω. The regulator will be instable at
Tamb = −30 °C (see Fig.14).
Solution
Use a tantalum capacitor of 10 µF or a larger electrolytic
capacitor. The use of tantalum capacitors is recommended
to avoid problems with stability at low temperatures.
handbook, halfpage
4
R
(Ω) 3
2
maximum ESR
MBK100
stable region
1
minimum ESR
0
1
10
100
C (µF)
Fig.13 Curves for selecting value of output
capacitor for regulator 1 and regulator 3.
handbook, halfpage
14
R 12
(Ω)
10
8
6
4
2
0
0.22
maximum ESR
MBK099
stable region
minimum ESR
1
10
100
C (µF)
Fig.14 Curves for selecting value of output
capacitor for regulator 2.
2003 Nov 28
15
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