tda3618jr-n1 NXP Semiconductors, tda3618jr-n1 Datasheet - Page 18

• Manufacturer Part Number: tda3618jr-n1
• 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 (output
noise of the regulators is translated into a current noise by
means of 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. The output capacitors can be selected
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.
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 two examples 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
73 F and the ESR is increased to 1.1 . The regulator will
remain 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 .
The regulator will be unstable at T
Fig.10).
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
Fig.10 Curve for selecting the value of output
amb
= 30 C the capacitor value is decreased to
( )
R
capacitor for regulator 2.
14
12
10
8
6
4
2
0
0.22
amb
amb
= 30 C the capacitor value is
= 30 C (see Fig.9).
1
minimum ESR
maximum ESR
stable region
10
amb
Product specification
TDA3618JR
C ( F)
= 30 C (see
MGK613
100