Datasheet

Data Sheet ADuCM360/ADuCM361
Rev. B | Page 3 of 24
GENERAL DESCRIPTION
The ADuCM360 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 ADuCM360 is designed for
direct interfacing to external precision sensors in both wired
and battery-powered applications. The ADuCM361 contains
all the features of the ADuCM360 except that only one 24-bit
Σ-Δ ADC (ADC1) is available.
The ADuCM360/ADuCM361 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 (SPI, UART, and I
2
C). Also integrated on chip
are 128 kB of nonvolatile Flash/EE memory and 8 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.
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 ref-
erence, but they can be configured to accept one or two external
reference sources in ratiometric measurement configurations. 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 ADuCM360/ADuCM361 integrate a range of on-chip
peripherals, which can be configured under microcontroller
software control as required in the application. The peripherals
include UART, I
2
C, 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 ADuCM360/ADuCM361 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 I
DD
). 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 ADuCM360/ADuCM361 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
device. This mode allows the part to operate with ultralow power
and still respond 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 parts 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.
More information on the ADuCM360/ADuCM361, see the
UG-367 user guide.