AT91SAM7S128 ATMEL [ATMEL Corporation], AT91SAM7S128 Datasheet - Page 12

• Manufacturer Part Number: AT91SAM7S128
• Manufacturer: ATMEL [ATMEL Corporation]

possible. One external 2.2 µF (or 3.3 µF) X7R capacitor must be connected between VDDOUT
and GND.
Adequate input supply decoupling is mandatory for VDDIN in order to improve startup stability
and reduce source voltage drop. The input decoupling capacitor should be placed close to the
chip. For example, two capacitors can be used in parallel: 100 nF NPO and 4.7 µF X7R.
6.4
Typical Powering Schematics
The AT91SAM7S Series supports a 3.3V single supply mode. The internal regulator is con-
nected to the 3.3V source and its output feeds VDDCORE and the VDDPLL.
Figure 6-1
shows
the power schematics to be used for USB bus-powered systems.
Figure 6-1.
3.3V System Single Power Supply Schematic
VDDFLASH
Power Source
VDDIO
ranges
DC/DC Converter
from 4.5V (USB)
to 18V
VDDIN
Voltage
3.3V
Regulator
VDDOUT
VDDCORE
VDDPLL
AT91SAM7S Series Summary
12
6175BS–ATARM–04-Nov-05