SAM7L128 Atmel Corporation, SAM7L128 Datasheet - Page 105

• Manufacturer Part Number: SAM7L128
• Manufacturer: Atmel Corporation

Specifications of SAM7L128

• Flash (kbytes): 128 Kbytes
• Pin Count: 144
• Max. Operating Frequency: 36 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 80
• Ext Interrupts: 80
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 3
• Segment Lcd: 40
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 4
• Adc Resolution (bits): 10
• Adc Speed (ksps): 460
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 6
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8/3.3
• Operating Voltage (vcc): 1.8 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

17.3
17.3.1
17.3.2
6257A–ATARM–20-Feb-08
Supply Controller Functional Description
Supply Controller Overview
Slow Clock Generator
The Supply Controller controls the power supplies of each section of the product:
The Supply Controller has its own reset circuitry and is clocked by the 32 kHz Slow clock
generator.
The reset circuitry is based on the NRSTB pin, a zero-power power-on reset cell and a brownout
detector cell. The zero-power power-on reset allows the Supply Controller to start properly, while
the software-programmable Brownout Detector detects either a battery discharge or main volt-
age loss.
The Slow Clock generator is based on a 32 kHz crystal oscillator and an embedded 32 kHz RC
oscillator. The Slow Clock defaults to the RC oscillator, but the software can enable the crystal
oscillator and select it as the Slow Clock source.
The Supply Controller starts up the device by sequentially enabling the internal power switches
and the Voltage Regulator, then generates the proper reset signals to the core power supply.
It also sets the system in different low power modes and wakes it up from a wide range of
events.
The Supply Controller embeds a slow clock generator that is supplied with the backup power
supply. As soon as FWUP is asserted, both the crystal oscillator and the embedded RC oscilla-
tor are powered up, but only the embedded RC oscillator is enabled. This allows the slow clock
to be valid in a short time (about 100 µs).
The user can select the crystal oscillator to be the source of the slow clock, as it provides a more
accurate frequency. The command is made by writing the Supply Controller Control Register,
SUPC_CR, with the XTALSEL bit at 1. This results in a sequence which first enables the crystal
oscillator, then waits for 32,768 slow clock cycles, then switches the slow clock on the output of
the crystal oscillator and then disables the RC oscillator to save power. The switch of the slow
clock source is glitch free. The OSCSEL bit of the Supply Controller Status Register, SUPC_SR,
allows knowing when the switch sequence is done.
Coming back on the RC oscillator is only possible by shutting down the backup power supply.
If the user does not need the crystal oscillator, the XIN and XOUT pins should be left
unconnected.
The user can also set the crystal oscillator in bypass mode instead of connecting a crystal. In
this case, the user has to provide the external clock signal on the XIN. The input characteristics
of the XIN pin are given in the product electrical characteristics section. In order to set the
• The Backup, including the Supply Controller, a part of the Reset Controller and the Slow
• The backup SRAM
• The Clock, including the Real Time Clock
• The Flash Memory
• The CORE, including the other part of the Reset Controller, the Processor and the
• the LCD controller, the charge pump and the LCD voltage regulator
Clock switcher
Peripherals
AT91SAM7L128/64 Preliminary
105