tda3618ajr NXP Semiconductors, tda3618ajr Datasheet - Page 18

• Manufacturer Part Number: tda3618ajr
• Description: Multiple Voltage Regulator With Switch And Ignition Buffers
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Application information
N
Table 1 Noise figures
Note
1. Measured at a bandwidth of 200 kHz.
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 to a current
noise by the output capacitors). When a high frequency
capacitor of 220 nF in parallel with an electrolytic capacitor
of 100 F is connected directly to pins 1 and 14 (supply
and ground), the noise is minimal.
S
The regulators are stabilized with the externally connected
output capacitors.
2002 Feb 12
handbook, halfpage
REGULATOR
TABILITY
OISE
Multiple voltage regulator with
switch and ignition buffers
Fig.9
1
2
3
( )
R
Curve for selecting the value of output
capacitor for regulators 1 and 3.
20
15
10
5
0
0.1
C
o
= 10 F
170
180
100
stable region
1
NOISE FIGURE ( V)
C
maximum ESR
o
10
= 47 F
130
120
70
C ( F)
MGK612
100
C
o
(1)
= 100 F
110
100
65
18
The output capacitors can be selected by using the graphs
of Figs 9 and 10. When an electrolytic capacitor is used,
the temperature behaviour of this output capacitor can
cause oscillations at a low temperature. The two examples
below show how an output capacitor value is selected.
Example 1
Regulators 1 and 3 are stabilized with an electrolytic
output capacitor of 220 F (ESR = 0.15 ). At
T
and the ESR is increased to 1.1 . The regulator remains
stable at T
Example 2
Regulator 2 is stabilized with a 10 F electrolytic capacitor
(ESR = 3 ). At T
decreased to 3 F and the ESR is increased to 23.1 .
Using Fig.10, the regulator will be unstable at
T
Solution
To avoid problems with stability at low temperatures, the
use of tantalum capacitors is recommended. Use a
tantalum capacitor of 10 F or a larger electrolytic
capacitor.
handbook, halfpage
amb
amb
Fig.10 Curve for selecting the value of output
= 30 C, the capacitor value is decreased to 73 F
= 30 C.
( )
R
amb
capacitor for regulator 2.
14
12
10
8
6
4
2
0
= 30 C.
0.22
amb
= 30 C, the capacitor value is
1
minimum ESR
maximum ESR
stable region
10
TDA3618AJR
Product specification
C ( F)
MGK613
100