TDF8553J NXP Semiconductors, TDF8553J Datasheet - Page 42

• Manufacturer Part Number: TDF8553J
• Description: I2C-bus controlled 4 X 50 Watt power amplifier and multiple voltage regulator
• Manufacturer: NXP Semiconductors

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NXP Semiconductors
TDF8553J_1
Objective data sheet
12.4.1 Example regulator 2
12.4 Stability
Table 17.
[1]
The regulators are made stable by connecting capacitors to the regulator outputs. The
stability can be guaranteed with almost any output capacitor if its Electric Series
Resistance (ESR) stays below the ESR curve shown in
capacitor is used, its behavior with temperature can cause oscillations at extremely low
temperature. Oscillation problems can be avoided by adding a 47 nF capacitor in parallel
with the electrolytic capacitor. The following example describes how to select the value of
output capacitor.
Regulator 2 is stabilized with an electrolytic output capacitor of 10 F which has an ESR
of 4 . At T
28
the regulator unstable. To avoid problems with stability at low temperatures, the
recommended solution is to use tantalum capacitors. Either use a tantalum capacitor of
10 F, or an electrolytic capacitor with a higher value.
Regulator
1
2
3
4
5
6
Fig 32. Curve for selecting the value of output capacitors for regulators 1 to 6
Measured in the frequency range 20 Hz to 80 kHz; at I
which is above the maximum allowed as shown in
Regulator noise figures
amb
= 30 C the capacitor value decreases to 3 F and its ESR increases to
Rev. 01 — 3 December 2008
Noise figure ( V)
C
225
700
100
235
315
710
o
ESR
( )
= 10 F
4
20
15
10
5
0
0.1
50 Watt power amplifier and multiple voltage regulator
[1]
stable region
1
C
180
600
85
205
285
550
maximum ESR
o
O(reg)
= 47 F
10
C ( F)
= 10 mA
Figure
Figure
100
mgl912
32. If an electrolytic
32, and which will make
C
145
390
65
175
225
340
TDF8553J
o
= 100 F
© NXP B.V. 2008. All rights reserved.
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