Circuit Note

CN-0221

Circuits from the Lab™ reference circuits are engineered and

tested for quick and easysystemintegrationto helpsolve today’s

analog, mixed-signal, and RF design challenges. For more

informationand/orsupport,visit www.analog.com/CN0221.

Devices Connected/Referenced

ADuCM360/

ADuCM361

Cortex-M3 Based Microcontroller with

Dual 24-Bit Σ-Δ ADCs

ADP1720-3.3

Low Dropout Linear Regulator

Microcontroller and an External Thermocouple

Rev. 0

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engineers. Standard engineering practices have been employed in the design and construction of

eachcircuit,andtheirfunctionandperformancehavebeentestedandverifiedinalabenvironmentat

room temperature. However, you are solely responsible for testing the circuit and determining its

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whatsoeverconnectedtotheuseofanyCircuitsfromtheLabcircuits. (Continuedonlastpage)

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EVALUATION AND DESIGN SUPPORT

Circuit Evaluation Board

CN-0221 Evaluation Board (EVAL-ADuCM360TCZ)

Design and Integration Files

Schematics, Layout Files, Bill of Materials, source code for

ADuCM360

CIRCUIT FUNCTION AND BENEFITS

This circuit uses the ADuCM360/ADuCM361 precision analog

microcontroller in an accurate thermocouple temperature

monitoring application. The ADuCM360/ADuCM361 integrates

dual 24-bit sigma-delta (Σ-Δ) analog-to-digital converters (ADCs),

dual programmable current sources, a 12-bit digital-to-analog

converter (DAC), and a 1.2 V internal reference, as well as an ARM

Cortex-M3 core, 126 kB flash, 8 kB SRAM, and various digital

In the circuit, the ADuCM360/ADuCM361 is connected to a

thermocouple and a 100 Ω platinum resistance temperature

detector (RTD). The RTD is used for cold junction compensation.

In the source code, an ADC sampling rate of 4 Hz is chosen. When

the ADC input programmable gain amplifier (PGA) is configured

for a gain of 32, the noise-free code resolution of the ADuCM360/

ADuCM361 is greater than 18 bits.

ADuCM360

AIN5/IEXC

AVDD

IOVDD

AIN0

RxD

RxD

TxD

TxD

RESET

P2.2/BM

RESET

SD

AIN1

5.6k

Ω

0.1%

100

Ω

PtRTD

AIN2

THERMOCOUPLE

JUNCTION

AIN3

J1

AIN7/VBIAS

AGND

BEAD

3.3V

BEAD

USB HEADER

10Ω

10Ω

10Ω

0.01µF

0.01µF

0.1µF

4.7µF

4.7µF

0.1µF

10µF

IN

5V

D–

D+

GND

OUT

GND

ADP1720-3.3

FT232R

BEAD

FERRITE BEADS:

1kΩ @ 100MHz

TAIYO YUDEN

BK2125HS102-T

0.1µF

SHIELD

Figure 1. ADuCM360/ADuCM361 as a Temperature Monitor Controller with a Thermocouple Interface (Simplified Schematic, All Connections Not Shown)