High Precision, Impedance, and Electrochemical Front End Data Sheet AD5940/AD5941 FEATURES 6 kB SRAM to preprogram AFE sequences Analog input Ultra low power potentiostat channel: 6.5 A of current 16-bit ADC with both 800 kSPS and 1.6 MSPS options consumption when powered on and all other blocks in Voltage, current, and impedance measurement capability hibernate mode Internal and external current and voltage channels Smart sensor synchronization and data collection Ultralow leakage switch matrix and input mux Cycle accurate control of sensor measurement Input buffers and programmable gain amplifier Sequencer controlled GPIOs Voltage DACs On-chip peripherals Dual output voltage DAC with an output range of 0.2 V SPI serial input/output to 2.4 V Wake-up timer 12-bit V output to bias potentiostat Interrupt controller BIAS0 6-bit V output to bias TIA Power ZERO0 Ultra low power: 1 A 2.8 V to 3.6 V supply 1 high speed, 12-bit DAC 1.82 V input/output compliant Power-on reset Output range to sensor: 607 mV Hibernate mode with low power DAC and potentiostat Programmable gain amplifier on output with gain amplifier powered up to maintain sensor bias settings of 2 and 0.05 Package and temperature range Amplifiers, accelerators, and references 3.6 mm 4.2 mm, 56-ball WLCSP 1 low power, low noise potentiostat amplifier suitable for 7 mm 7 mm, 48-lead LFCSP potentiostat bias in electrochemical sensing AD5940 and AD5941 fully specified for operating 1 low noise, low power TIA, suitable for measuring sensor temperature range of 40C to +85C current output AD5941W fully specified for operating temperature range 50 pA to 3 mA range of 40C to +105C Programmable load and gain resistors for sensor output AEC-Q100 qualified for automotive applications Analog hardware accelerators Digital waveform generator APPLICATIONS Receive filters Electrochemical measurements Complex impedance measurement (DFT) engine Electrochemical gas sensors 1 high speed TIA to handle wide bandwidth input signals Potentiostat/amperometric/voltammetry/cyclic from 0.015 Hz up to 200 kHz voltammetry Digital waveform generator for generation of sinusoid and Bioimpedance applications trapezoid waveforms Skin impedance 2.5 V and 1.82 V internal reference voltage sources Body impedance System level power savings Continuous glucose monitoring Fast power-up and power-down analog blocks for duty Battery impedance cycling Programmable AFE sequencer to minimize workload of host controller SIMPLIFIED BLOCK DIAGRAM POTENTIOSTAT: AMPLIFIER AND DAC WAVEFORM GENERATOR ADC FIFO AND MMR CURRENT CHANNELS DFT 16-BIT VOLTAGE ADC CHANNELS DIGITAL DATA FIFO FILTERS INTERNAL CHANNELS SLEEP/WAKEUP LDOs SEQUENCER TEMPERATURE TIMER CHANNEL VOLTAGE INTERRUPTION GPIOs SPI REFERENCES GENERATOR IMPEDANCE ENGINE AMPLIFIERS AND DAC Figure 1. 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Trademarks and registered trademarks are the property of their respective owners. 16778-201AD5940/AD5941 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Avoiding Incoherency Errors Between Excitation and Measurement Frequencies During Impedance Measurements Applications ....................................................................................... 1 ....................................................................................................... 44 Simplified Block Diagram ............................................................... 1 High Speed DAC Calibration Options .................................... 45 Revision History ............................................................................... 3 High Speed DAC Circuit Registers .......................................... 46 Functional Block Diagram .............................................................. 5 High Speed TIA Circuits ............................................................... 49 General Description ......................................................................... 6 High Speed TIA Configuration ................................................ 49 Specifications ..................................................................................... 7 High Speed TIA Circuit Registers ............................................ 51 ADC RMS Noise Specifications ............................................... 16 High Performance ADC Circuit ................................................... 53 SPI Timing Specifications ......................................................... 17 ADC Circuit Overview .............................................................. 53 Absolute Maximum Ratings .......................................................... 18 ADC Circuit Diagram ............................................................... 53 Thermal Resistance .................................................................... 18 ADC Circuit Features ................................................................ 54 ESD Caution ................................................................................ 18 ADC Circuit Operation ............................................................. 54 Pin Configuration and Function Descriptions ........................... 19 ADC Transfer Function ............................................................. 54 Typical Performance Characteristics ........................................... 22 ADC Low Power Current Input Channel ............................... 55 Reference Test Circuit ................................................................ 24 Selecting Inputs to ADC Mux .................................................. 55 Theory of Operation ...................................................................... 25 ADC Postprocessing .................................................................. 56 Configuration Registers ............................................................. 25 Internal Temperature Sensor Channel .................................... 56 Silicon Identification ...................................................................... 28 Sinc2 Filter (50 Hz/60 Hz Mains Filter) .................................. 56 Identification Registers .............................................................. 28 ADC Calibration ........................................................................ 56 System Initialization ....................................................................... 29 ADC Circuit Registers ............................................................... 57 Low Power DAC ............................................................................. 30 ADC Calibration Registers ....................................................... 63 Low Power DAC Switch Options ............................................. 30 ADC Digital Postprocessing Registers (Optional) ................ 69 Relationship Between the 12-Bit and 6-Bit Outputs .............. 31 ADC Statistics Registers ............................................................ 70 Low Power DAC Use Cases ....................................................... 31 Programmable Switch Matrix ....................................................... 71 Low Power DAC Circuit Registers ........................................... 32 Switch Descriptions ................................................................... 71 Low Power Potentiostat ................................................................. 35 Recommended Configuration in Hibernate Mode ............... 71 Low Power TIA ............................................................................... 36 Options for Controlling All Switches ...................................... 71 Low Power TIA Protection Diodes .......................................... 36 Programmable Switches Registers ........................................... 74 Using an External R ............................................................... 36 TIA Precision Voltage References ........................................................ 84 Recommended Switch Settings for Various Operating Modes High Power and Low Power Buffer Control Register ....................................................................................................... 36 BUFSENCON ............................................................................. 85 Low Power TIA Circuits Registers ........................................... 39 Sequencer ........................................................................................ 86 High Speed DAC Circuits .............................................................. 42 Sequencer Features ..................................................................... 86 High Speed DAC Output Signal Generation .......................... 42 Sequencer Overview .................................................................. 86 Power Modes of the High Speed DAC Core ........................... 42 Sequencer Commands ............................................................... 86 High Speed DAC Filter Options ............................................... 42 Sequencer Operation ................................................................. 88 High Speed DAC Output Attenuation Options ......................... 44 Sequencer and FIFO Registers ................................................. 90 High Speed DAC Excitation Amplifier ................................... 44 Waveform Generator...................................................................... 95 Coupling an AC Signal from the High Speed DAC to the DC Waveform Generator Features .................................................. 95 Level Set by the Low Power DAC ............................................. 44 Waveform Generator Operation .............................................. 95 Rev. 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