ADUCM362BCPZ256

The ADuCM362/ADuCM363 is a fully integrated, 3.9 kSPS, 24-bit data acquisition system that incorporates dual, high performance, multichannel sigma-delta (Σ-Δ) analog-to-digital converters (ADCs), a 32-bit ARM Cortex™-M3 processor, and Flash/EE memory on a single chip. The ADuCM362/ ADuCM363 are designed for direct interfacing to external precision sensors in both wired and battery-powered applications. The ADuCM363 contains all the features of the ADuCM362, except that only one 24-bit Σ-Δ ADC (ADC1) is available.

The ADuCM362/ADuCM363 contain an on-chip 32 kHz oscillator and an internal 16 MHz high frequency oscillator. The high frequency oscillator is routed through a programmable clock divider from which the operating frequency of the processor core clock is generated. The maximum core clock speed is 16 MHz; this speed is not limited by operating voltage or temperature.

The microcontroller core is a low power ARM Cortex-M3 processor, a 32-bit RISC machine that offers up to 20 MIPS peak performance. The Cortex-M3 processor incorporates a flexible, 11-channel DMA controller that supports all wired communica-tion peripherals (both SPIs, both UARTs, and I2C). Also integrated on chip are up to 256 kB of nonvolatile Flash/EE memory and 24 kB of SRAM.

The analog subsystem consists of dual ADCs, each connected to a flexible input mux. Both ADCs can operate in fully differential and single-ended modes. Other on-chip ADC features include dual programmable excitation current sources, diagnostic current sources, and a bias voltage generator of AVDD_REG/2 (900 mV) to set the common-mode voltage of an input channel. A low-side internal ground switch is provided to allow power-down of an external circuit (for example, a bridge circuit) between conversions. Optional input buffers are provided for the analog inputs and the external reference inputs. These buffers can be enabled for all PGA gain settings.

The ADCs contain two parallel filters: a sinc3 or sinc4 filter in parallel with a sinc2 filter. The sinc3 or sinc4 filter is used for precision measurements. The sinc2 filter is used for fast measure-ments and for the detection of step changes in the input signal.

The devices contain a low noise, low drift internal band gap reference, but they can be configured to accept one or two external reference sources in ratiometric measurement config-urations. An option to buffer the external reference inputs is provided on chip. A single-channel buffered voltage output DAC is also provided on chip.

The ADuCM362/ADuCM363 integrate a range of on-chip peripherals, which can be configured under microcontroller software control as required in the application. The peripherals include two UARTs, I2C, and dual SPI serial I/O communication controllers; a 19-pin GPIO port; two general-purpose timers; a wake-up timer; and a system watchdog timer. A 16-bit PWM controller with six output channels is also provided.

The ADuCM362/ADuCM363 are specifically designed to operate in battery-powered applications where low power operation is critical. The microcontroller core can be configured in a normal operating mode that consumes 290 μA/MHz (including flash/SRAM IDD). An overall system current consumption of 1 mA can be achieved with both ADCs on (input buffers off), PGA gain of 4, one SPI port on, and all timers on.

The ADuCM362/ADuCM363 can be configured in a number of low power operating modes under direct program control, including a hibernate mode (internal wake-up timer active) that consumes only 4 μA. In hibernate mode, peripherals, such as external interrupts or the internal wake-up timer, can wake up the devices. This mode allows the devices to operate with ultralow power while still responding to asynchronous external or periodic events.

On-chip factory firmware supports in-circuit serial download via a serial wire interface (2-pin JTAG system) and UART; non-intrusive emulation is also supported via the serial wire interface. These features are incorporated into a low cost QuickStart™ Development System that supports this precision analog micro-controller family.

The devices operate from an external 1.8 V to 3.6 V voltage supply and are specified over an industrial temperature range of −40°C to +125°C.

Applications

• Industrial automation and process control
• Intelligent precision sensing systems
• 4 mA to 20 mA loop-powered smart sensor systems
• Medical devices, patient monitoring