AT91SAM7S256 Summary Preliminary

Description

   Atmel’s AT91SAM7S256 is a member of a series of low pincount Flash                                                        microcontrollers based on the 32-bit ARM RISC processor. It features a 256 Kbyte high-                                 speed Flash and a 64 Kbyte SRAM, a large set of peripherals, including a USB 2.0 device,                             and a complete set of system functions minimizing the number of external components.                                   The device is an ideal migration path for 8-bit microcontroller users looking for additional              performance and extended memory. The embedded Flash memory can be programmed in-system via the JTAG-ICE interface or via a parallel interface on a production programmer prior to mounting. Built-in lock bits and a security bit protect the firmware from accidental overwrite and preserves its confidentiality. The AT91SAM7S256 system controller includes a reset controller capable of managing the power-on sequence of the microcontroller and the complete system. Correct device operation can be monitored by a built-in brownout detector and a watchdog running off an integrated RC oscillator. The AT91SAM7S256 is a general-purpose microcontroller. Its integrated USB Device port makes it an ideal device for peripheral applications requiring connectivity to a PC or cellular phone. Its aggressive price point and high level of integration pushes its scope of use far into the cost-sensitive, high-volume consumer market.

Power Supplies

  The AT91SAM7S256 has six types of power supply pins and integrates a voltage regulator, allowing the device to be supplied with only one voltage. The six power supply pin types are: • VDDIN pin. It powers the voltage regulator and the ADC; voltage ranges from 3.0V to 3.6V, 3.3V nominal. If the voltage regulator is not used, VDDIN should be connected to GND. • VDDOUT pin. It is the output of the 1.8V voltage regulator. • VDDIO pin. It powers the I/O lines and the USB transceivers; dual voltage range is supported. Ranges from 3.0V to 3.6V, 3.3V nominal. Note that supplying less than 3.0V to VDDIO prevents any use of the USB transceivers. • VDDFLASH pin. It powers a part of the Flash and is required for the Flash to operate correctly; voltage ranges from 3.0V to 3.6V, 3.3V nominal. • VDDCORE pins. They power the logic of the device; voltage ranges from 1.65V to 1.95V, 1.8V typical. It can be connected to the VDDOUT pin with decoupling capacitor. VDDCORE is required for the device, including its embedded Flash, to operate correctly. • VDDPLL pin. It powers the oscillator and the PLL. It can be connected directly to the VDDOUT pin. No separate ground pins are provided for the different power supplies. Only GND pins are provided and should be connected as shortly as possible to the system ground plane.