at91sam7l128 ATMEL Corporation, at91sam7l128 Datasheet - Page 32

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

9.4
32
Clock Generator
AT91SAM7L128/64 Preliminary
BOD current consumption is 25 µA, typically.
To decrease current consumption, the software can disable the brownout detector, especially in
low-power mode.
The software can also configure the BOD in “switched” mode. In this mode, an internal state
machine switches on and off periodically and stores the output of the BOD.
This decreases the current consumption (inferior to 2 µA) while the detection is still active. This
feature is suitable in low-power mode where voltage detection is still needed.
The clock generator embeds one low-power RC oscillator, one fast RC oscillator, one crystal
oscillator and one PLL with the following characteristics:
It provides SLCK, MAINCK and PLLCK.
The Supply Controller selects between the internal RC oscillator and the 32 kHz crystal oscilla-
tor. The unused oscillator is disabled so that power consumption is optimized.
The 2 MHz Fast RC oscillator is the default selected clock (MAINCK) which is used at start-up .
The user can select an external clock (CLKIN) through software.
The PLL needs an external RC filter and starts up in a very short time (inferior to 1 ms).
• RC Oscillator ranges between 22 kHz and 42 kHz
• Fast RC Oscillator ranges between 1.5 MHz and 2.5 MHz
• Crystal Oscillator at 32 kHz (can be bypassed)
• PLL output ranges between 18 MHz and 47 MHz
6257AS–ATARM–28-Feb-08