ATA6621 ATMEL Corporation, ATA6621 Datasheet - Page 12

• Manufacturer Part Number: ATA6621
• Manufacturer: ATMEL Corporation

3.15
12
Voltage Regulator
ATA6621
The voltage regulator needs an external capacitor for compensation and to smooth the distur-
bances from the microcontroller. It is recommend to use an electrolytic capacitor with C > 1.8 µF
and a tantalum capacitor with C = 100 nF. The values of these capacitors can be varied by the
customer, depending on the application.
During mode change from Silent to Normal Mode, the voltage regulator ramps up to 6V for only
a few microseconds before it drops back to 5V. This behavior depends on the value of the load
capacitor. With 4.7 µF, the overshoot voltage has its greatest value. This voltage decreases with
higher or lower load capacitors.
The main power dissipation of the IC is created from the V
needed for the application.
In
Figure 3-6.
• The WD_OSC pin is a constant voltage regulator which supplies 2.5V for the external resistor
Figure 3-7 on page 13
ROSC to adjust the watchdog timing. This output is short circuit protected. A short circuit to
GND causes a reset a pin NRES after typically 4 ms. An open circuit causes a reset at pin
NRES after typically 7 ms.
NRES
VCC
VS
V
5.5V
12V
thun
3V
5V
5V
VCC Voltage Regulator: Ramp Up and Undervoltage
you see the safe operating range of the ATA6621.
t
vcc
t
res
CC
output current I
t
res_f
4887B–AUTO–01/06
VCC
, which is
t
t
t