Part Number: AT91SAM7A3-AU

Manufacturer: Microchip Technology

Description: IC MCU 16/32B 256KB FLSH 100LQFP

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Technical Specifications of AT91SAM7A3-AU

Datasheet  AT91SAM7A3-AU datasheet
Category Integrated Circuits (ICs)
Family Embedded – Microcontrollers
Manufacturer Atmel
Series AT91SAM
Packaging Tray
Part Status Obsolete
Core Processor ARM7?
Core Size 16/32-Bit
Speed 60MHz
Connectivity CAN, I2C, Memory Card, SPI, SSC, UART/USART
Peripherals POR, PWM, WDT
Number of I/O 62
Program Memory Size 256KB (256K x 8)
Program Memory Type FLASH
RAM Size 32K x 8
Voltage – Supply (Vcc/Vdd) 1.65 V ~ 1.95 V
Data Converters A/D 8x10b
Oscillator Type Internal
Operating Temperature -40°C ~ 85°C (TA)
Package / Case 100-LQFP
Supplier Device Package 100-LQFP (14×14)

A family of 32-bit ARM7TM microcontrollers with built-in CAN controllers includes the AT91SAM7A3. It includes many peripherals, including two 2.0B full CAN controllers, a 256-Kbyte high-speed Flash and 32-Kbyte SRAM, and a comprehensive set of system functions, reducing the number of external components. The device provides the perfect migration path for users of 8-bit microcontrollers searching for increased performance and expanded memory.

Using the JTAG-ICE interface, the embedded Flash memory can be programmed in-system. The firmware is protected from unintentional overwriting by built-in lock bits. A full complement of debugging facilities is integrated into the AT91SAM7A3, including a JTAG Embedded ICE interface, a misalignment detector, an interrupt-driven debug communication channel for user-configurable tracing on a console, and JTAG boundary scan for board-level debug and testing. The AT91SAM7A3 is perfect for many compute-intensive embedded control applications because it integrates a high-performance 32-bit RISC processor with a high-density 16-bit instruction set, Flash and SRAM memory, a wide range of peripherals including CAN controllers, 10-bit ADC, Timers, and serial communication channels on a monolithic chip.

AT91SAM7A3-AU Power Considerations

● Power Supplies

The AT91SAM7A3 includes five different power pins labeled VDD3V3. The voltage regulator, the I/O lines, the Flash, and the USB transceivers are all powered by the same 3.0V–3.6V (nominal 3.3V) supply.

Connectors for VDD1V8 power. Both provide energy to the device’s logic as the 1.8V voltage regulator outputs.

Pin VDDPLL. It supplies power to the PLL, typically at a value of 1.8V but ranging from 1.65V to 1.95V. With a decoupling capacitor, they can be wired to the VDD1V8 terminal.

a pin labeled VDDBU. It operates between 3.0V and 3.6V, with a nominal of 3.3V, and supplies energy to the Slow Clock oscillator, Real Time Clock, and some of the System Controller.

Pin VDDANA. The ADC operates on this supply, which has a voltage range of 3.0V to 3.6V (nominal 3.3V). There are no dedicated ground pins for the various power sources. The only available pins are GND, which must be connected to the ground plane of the system as soon as possible.

● Voltage Regulator

A voltage regulator is built into the AT91SAM7A3 and can provide up to 130 mA of output current while consuming less than 120 A of static current. To lessen ripple and forestall oscillations, VDD1V8 (pin 99) must be adequately decoupled from the rest of the output supply. The easiest approach is to utilize two capacitors in parallel, specifically, an external 470 pF (or 1 nF) NPO capacitor linked as close to the chip as feasible between VDD1V8 and GND.

Between VDD1V8 and GND, an external 3.3 F (or 4.7 F) X7R capacitor is required. External connections and appropriate decoupling capacitors are required for all additional VDD1V8 pins (at least 100 nF). Improve startup stability and lower source voltage loss by properly decoupling VDD3V3 (pin 100) from the input supply. It is recommended to position the input decoupling capacitor close to the chip. Parallel usage of two capacitors of different values (say, 100 nF NPO and 4.7 F X7R) is possible. For any other pins to receive power, a decoupling capacitor and external connection to VDD3V3 are required (at least 100 nF).

I/O Lines Considerations

● JTAG Port Pins

The schmitt trigger inputs are TMS, TDI, and TCK. While TMS and TCK can operate at 5V, TDI cannot. No internal resistors are integrated into TMS, TDI, or TCK; an external pull-up is required. Voltages power the TDO output up to VDD3V3. By asserting the JTAGSEL pin to a high level, the user can do a boundary scan using the JTAG. The JTAGSEL pin does not need to be connected for normal operation because it includes a permanent pull-down resistor.

● Test Pin

The TST pin has a pull-down resistor built in for usage during manufacturing tests but can be disconnected during regular use. The outcomes of high-speed driving along this route are arbitrary.

● Reset Pin

As such, the NRST pin can be used either way. It can be asserted externally to reset the microcontroller or driven low by the on-chip reset controller to trigger a reset. The reset controller can provide a guaranteed minimum pulse length, and the length of the reset pulse is not limited in any way. Because of this, the NRST signal can be used to reset every part of the system with the push of a button connected to the NRST pin as a user reset.

Two Lines from a PIO Controller (A and B) All of the I/O lines, from PA0 to PA31 and PB0 to PB29, have a programmable pull-up resistor and can operate from 5V. With the PIO Controllers, this pull-up resistor can be programmed individually for each I/O line. Tolerance for voltages up to 5.5V means that the I/O lines can be driven at a lower voltage than the nominal VDD3V3. However, when the programmable pull-up resistor is enabled and a voltage greater than VDD3V3 is applied to an I/O line, current flows via the pull-up resistor from the I/O line to VDDIO. All I/O lines are set as inputs at reset, with a pull-up resistor enabled. Thus, extra caution is required.

● Shutdown Logic Pins

To put it simply, the SHDW pin is an open drain output. Using a pull-up resistor connected externally, it can be connected to VDDBU. There is no output from the FWUP, WKUP0, or WKUP1 pins. They only work with voltages between 0V and VDDBU. Ground or VDDBU should be connected to these pins, and an external resistor should be used if possible.


In conclusion, the AT91SAM7A3 microcontroller is an outstanding choice for embedded control applications that require high performance and versatility. Its powerful 32-bit RISC processor, a wide range of peripherals, and advanced debugging facilities offer a comprehensive solution for compute-intensive projects. The device’s built-in voltage regulator and power pins also make it easy to integrate external components. The AT91SAM7A3 is a great option for users seeking increased performance and expanded memory from their 8-bit microcontrollers.

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