TDA3618AJR Datasheet, PDF (18/24 Pages) NXP Semiconductors – Multiple voltage regulator with switch and ignition buffers

Philips Semiconductors
Multiple voltage regulator with
switch and ignition buffers
Product specification
TDA3618AJR
Application information
NOISE
Table 1 Noise figures
NOISE FIGURE (µV)⁽¹⁾
REGULATOR
C_o = 10 µF C_o = 47 µF C_o = 100 µF
1
170
130
110
2
180
120
100
3
100
70
65
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 µF is connected directly to pins 1 and 14 (supply
and ground), the noise is minimal.
STABILITY
The regulators are stabilized with the externally connected
output capacitors.
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 µF (ESR = 0.15 Ω). At
T_amb = −30 °C, the capacitor value is decreased to 73 µF
and the ESR is increased to 1.1 Ω. The regulator remains
stable at T_amb = −30 °C.
Example 2
Regulator 2 is stabilized with a 10 µF electrolytic capacitor
(ESR = 3 Ω). At T_amb = −30 °C, the capacitor value is
decreased to 3 µF and the ESR is increased to 23.1 Ω.
Using Fig.10, the regulator will be unstable at
T_amb = −30 °C.
Solution
To avoid problems with stability at low temperatures, the
use of tantalum capacitors is recommended. Use a
tantalum capacitor of 10 µF or a larger electrolytic
capacitor.
handbook, halfpa₂g₀e
R
(Ω)
15
10
5
0
0.1
MGK612
maximum ESR
stable region
1
10 _{C (µF)} 100
handbook, halfpage
14
R
(Ω) ₁₂
10
8
6
4
2
0
0.22
maximum ESR
MGK613
stable region
minimum ESR
1
10 _{C (µF)} 100
Fig.9 Curve for selecting the value of output
capacitor for regulators 1 and 3.
2001 May 02
Fig.10 Curve for selecting the value of output
capacitor for regulator 2.
18