at91sam7l128 ATMEL Corporation, at91sam7l128 Datasheet - Page 15

• Manufacturer Part Number: at91sam7l128
• Description: At91 Arm Thumb-based Microcontroller
• Manufacturer: ATMEL Corporation

5.5
6257AS–ATARM–28-Feb-08
Voltage Regulator
Figure 5-2.
The AT91SAM7L128/64 embeds a voltage regulator that is managed by the supply controller.
This internal regulator is only intended to supply the internal core of AT91SAM7L128/64. It fea-
tures three different operating modes:
Furthermore, in normal and deep modes, the regulator output voltage can be programmed by
software with 4 different steps within the range of 1.55V to 1.80V. The default output voltage is
1.80V in both normal and deep modes. The voltage regulator can regulate 1.80V output voltage
as long as the input voltage is above 1.95V. Below 1.95V input voltage, the output voltage
remains above 1.65V.
Output voltage adjusting ability allows current consumption reduction on VDDCORE and also
enables programming a lower voltage when the input voltage is lower than 1.95V.
At 1.55V, the Flash is still functional but with slower read access time. Programming or erasing
the Flash is not possible under these conditions. MCK maximum frequency is 25 MHz with
VDDCORE at 1.55V (1.45V minimum).
The regulator has an indicator that can be used by the software to show that the output voltage
has the correct value (output voltage has reached at least 80% of the typical voltage). This flag
is used by the supply controller. This feature is only possible when the voltage regulator is in
normal mode at 1.80V.
Adequate output supply decoupling is mandatory for VDDOUT in order to reduce ripple and
avoid oscillations. One external 2.2 µF (or 3.3 µF) X7R capacitor must be connected between
VDDOUT and GND.
• In normal mode, the voltage regulator consumes less than 30 µA static current and draws
• In deep mode, the current consumption of the voltage regulator is less than 8.5 µA. It can
• In shutdown mode, the voltage regulator consumes less than 1 µA while its output is driven
60 mA of output current.
draw up to 1 mA of output current. The default output voltage is 1.80V and the start-up time to
reach normal mode is inferior to 400 µs.
internally to GND. The default output voltage is 1.80V and the start-up time to reach normal
mode is inferior to 400 µs.
WKUP15
Fast Start-Up Circuitry
WKUP0
WKUP1
FSTT15
FSTT0
FSTT1
AT91SAM7L128/64 Preliminary
fast_restart
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