Circuit Note CN-0372 Devices Connected/Referenced 2 AD7091R-5 4-Channel, I C, Ultralow Power, 12-Bit ADC Circuits from the Lab reference designs are engineered and Ultralow Power Boost Regulator with ADP5090 tested for quick and easy system integration to help solve todays MPPT and Charge Management analog, mixed-signal, and RF design challenges. For more 0.2 V/C Offset Drift, 105 MHz Low information and/or support, visit www.analog.com/CN0372. ADA4805-1 Power, Low Noise, Rail-to-Rail Amplifier 2 MHz, Synchronous Boost DC-to-DC ADP1607 Converter Ultralow Power, General-Purpose, Multichannel Data Acquisition System with Energy Harvesting Circuit and Alert Function EVALUATION AND DESIGN SUPPORT CIRCUIT FUNCTION AND BENEFITS Circuit Evaluation Boards The circuit shown in Figure 1 is an ultralow power, multichannel CN-0372 Circuit Evaluation Board (EVAL-CN0372-PMDZ) data acquisition system that can be powered by a photovoltaic System Demonstration Platform (EVAL-SDP-CB1Z) (PV) cell or thermoelectric generator (TEG). The circuit uses SDP-I-PMOD Interposer Board (SDP-PMD-IB1Z) the industrys lowest power, multichannel, 12-bit successive Design and Integration Files approximation analog-to-digital converter (SAR ADC), the Schematics, Layout Files, Bill of Materials AD7091R-5, along with an efficient energy harvesting circuit based on the ADP5090 boost regulator. The ADC has a typical power consumption of 100 W on a single 3 V supply when sampling at 22 kSPS. Typical signal-to-noise ratio (SNR) is 68 dB for a 1 kHz input signal. The low power consumption and small form factor make this combination of devices ideally suited for portable low power applications, particularly for wearable and self-powered devices. Rev. 0 Circuits from the Lab reference designs from Analog Devices have been designed and built by Analog Devices engineers. Standard engineering practices have been employed in the design and construction of each circuit, and their function and performance have been tested and verified in a lab environment at room temperature. However, you are solely responsible for testing the circuit and determining its One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. suitability and applicability for your use and application. Accordingly, in no event shall Analog Devices be Tel: 781.329.4700 www.analog.com liable for direct, indirect, special, incidental, consequential or punitive damages due to any cause Fax: 781.461.3113 2015 Analog Devices, Inc. All rights reserved. whatsoever connected to the use of any Circuits from the Lab circuits. (Continued on last page) CN-0372 Circuit Note PHOTOVOLTAIC CELL ADP5090 P IN 2.2H SW SYS COLD-START VIN CHARGE PUMP ADP1607 MPPT 1 5 VIN SW BAT C 6 V RECHARGEABLE VOUT + IN DD CBP MPPT BOOST BATTERY OR 10F R1 CONTROL REGULATOR SUPERCAPACITOR ON C 3 OUT OFF FB 2 EN GND 10F R2 MINOP 4 PGOOD TO MCU REF CHARGE CONTROL AND DIS SW FROM MCU POWER PATH OPTIONAL SUPPLY SETSD MANAGEMENT BACK UP SETPG OPTIONAL + PRIMARY V DD TERM BATTERY AGND PGND ADA4805-1 MUX ADC OUT IN REF / IN MUX ADC V OUT IN DD REF REGCAP OUT OPTIONAL BUFFER 2.5V VREF V 0 IN 12-BIT V 1 IN SUCCESSIVE ANALOG INPUT T/H V 2 APPROXIMATION IN INPUTS MUX ADC V 3 IN ON-CHIP RESET OSC CONVST/GPO CHANNEL 1 SEQUENCER SDA CONTROL LOGIC SCL 2 I C INTERFACE AS 0 AS 1 AD7091R-5 V DRIVE GND ALERT/BUSY/ GPO GND 2 GPO 0 Figure 1. Low Power Data Acquisition System with Energy Harvesting Circuit (Simplified Schematic: All Connections and Decoupling Not Shown) An on-chip, accurate 2.5 V reference is available on the CIRCUIT DESCRIPTION REFIN/REFOUT pin. This circuit provides an optimized low power compact solution for multichannel system monitoring. These characteristics are The AD7091R-5 has an autocycle mode that allows the user to configure the ADC for autonomous operation and is ideal for the particularly important in wearable and self-powered monitoring of events outside of a user defined range. Conversions applications where form factor and power consumption are automatically take place at configured intervals as shown in critical system specifications. Table 25 of the AD7091R-5 data sheet. Typically, this mode is used Analog-to-Digital Converter to monitor a selection of channels with limit registers programmed The AD7091R-5 is a 12-bit, ultralow power, successive to signal out of bounds conditions via the alert function. approximation ADC. The device operates from a single 2.7 V to Energy Harvester 5.25 V power supply. This ADC features an on-chip conversion 2 The ADP5090 is an integrated boost regulator that converts dc clock, an accurate reference, and an I C interface that operates in power from photovoltaic cells or thermoelectric generators. The both standard (fSCL = 100 kHz) and fast (fSCL = 400 kHz) modes. device charges storage elements (rechargeable battery or super The conversion process and data acquisition are controlled using capacitor). The CN-0372 board uses a super capacitor that 2 the I C interface and an internal oscillator. The AD7091R-5 supplies power for small electronic devices and battery-free interface allows data read after the conversion, achieving a systems. The ADP5090 provides efficient conversion of the maximum 22.22 kSPS throughput rate in fast mode. This small amounts of harvested power available from PV cells or device uses advanced design and process techniques to achieve TEGs. The ADP5090 operates on an input power range from ultralow power dissipation without compromising performance. 16 W to 200 mW range with sub-microwatt operation losses. Rev. 0 Page 2 of 11 13582-001