tda3609jr NXP Semiconductors, tda3609jr Datasheet - Page 16

• Manufacturer Part Number: tda3609jr
• 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 made stable with the external
connected output capacitors.
1997 Aug 15
handbook, halfpage
REGULATOR
TABILITY
OISE
Multiple voltage regulator with switch and
ignition buffers
Fig.8
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 C
tbf
tbf
tbf
stable region
1
NOISE FIGURE ( V)
maximum ESR
O
10
= 47 F C
150
150
200
C ( F)
MGK612
100
O
(1)
= 100 F
tbf
tbf
tbf
16
The output capacitors can be selected using the graphs of
Figs 8 and 9. When an electrolytic capacitor is used, the
temperature behaviour of this output capacitor can cause
oscillations at a low temperature. The next 2 examples
show how an output capacitor value is selected.
Example 1
Regulators 1 and 3 are made stable with an electrolytic
output capacitor of 220 F (ESR = 0.15 ). At 30 C the
capacitor value is decreased to 73 F and the ESR is
increased to 1.1 . The regulator will remain stable at
Example 2
Regulator 2 is made stable with a 10 F electrolytic
capacitor (ESR = 3 ). At 30 C the capacitor value is
decreased to 3 F and the ESR is increased to 23.1 .
Using Fig.9, the regulator will be instable at 30 C.
Solution
Use a tantalum capacitor of 10 F or a larger electrolytic
capacitor. To avoid problems with stability at low
temperatures, the use of tantalum capacitors is
recommended.
handbook, halfpage
30 C.
Fig.9
( )
R
Curve for selecting the value of output
capacitor for regulator 2.
14
12
10
8
6
4
2
0
0.22
1
minimum ESR
maximum ESR
stable region
Preliminary specification
10
TDA3609JR
C ( F)
MGK613
100