Rainbow Electronics ATA6631 - Manual (Page 14)

14
9165A–AUTO–11/09
ATA6629/ATA6631
6. Voltage Regulator
Figure 6-1. V
CC
Voltage Regulator: Ramp Up and Undervoltage
The voltage regulator needs an external capacitor for compensation and to smooth the distur-
bances from the microcontroller. It is recommended to use an electrolytic capacitor with
C > 1.8 µF and a ceramic capacitor with C = 100 nF. The values of these capacitors can be var-
ied by the customer, depending on the application.
With this special SO8 package (fused lead frame to pin 3) an R
thja
of 80 K/W is achieved.
Therefore, it is recommended to connect pin 3 with a wide GND plate on the printed board to get
a good heat sink.
The main power dissipation of the IC is created from the V
CC
output current I
VCC
, which is
needed for the application.
Figure 6-2 shows the safe operating area of the ATA6629/ATA6631.
NRES
5V/3.3V
VCC
VS
5V/3.3V
V
thun
t
res_f
t
Reset
t
VCC
5.5V/3.8V
12V