Datasheet AD7783 (Analog Devices)

Read-Only, Pin Configured 24-Bit
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ADC with Excitation Current Sources AD7783 FEATURES FUNCTIONAL BLOCK DIAGRAM Single-Channel, 24-Bit
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ADC Pin Configurable (No Programmable Registers) VDD GND REFIN(+) REFIN(–) XTAL1 XTAL2 ISOURCE Select™ VDD Pin Programmable Input Ranges (
±
2.56 V or
±
160 mV) IEXC1 IEXC2 200
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A 200
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A Fixed 19.79 Hz Update Rate IOUT1 OSCILLATOR Simultaneous 50 Hz and 60 Hz Rejection AND PLL IOUT2 24-Bit No Missing Codes IPIN 18.5-Bit p-p Resolution (
±
2.56 V Range) 16.5-Bit p-p Resolution (
±
160 mV Range) SERIAL DOUT/RDY AIN(+) INTERFACE 24-BIT
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MUX BUF PGA AND SCLK ADC INTERFACE AIN(–) CONTROL LOGIC MODE Master or Slave Mode of Operation Slave Mode 3-Wire Serial CS AD7783 SPI®, QSPI™, MICROWIRE™, and DSP-Compatible Schmitt Trigger on SCLK RANGE POWER Specified for Single 3 V and 5 V Operation Normal: 1.3 mA @ 3 V BASIC CONNECTION DIAGRAM Power-Down: 9
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A POWER SUPPLY ON-CHIP FUNCTIONS Rail-to-Rail Input Buffer and PGA VDD AD7783 APPLICATIONS ANALOG AIN(+) CS Sensor Measurement INPUT AIN(–) DIGITAL Industrial Process Control DOUT/RDY INTERFACE CURRENT IOUT1 SCLK Temperature Measurement SOURCES IOUT2 XTAL1 Pressure Measurement 32.768kHz REFERENCE REFIN(+) Weigh Scales CRYSTAL INPUT REFIN(–) XTAL2 Portable Instrumentation GND GENERAL DESCRIPTION
The device operates from a 32.768 kHz crystal with an on-chip The AD7783 is a complete analog front end for low frequency PLL generating the required internal operating frequency. The measurement applications. The 24-bit sigma-delta ADC con- output data rate from the part is fixed via the master clock at tains one fully differential input channel that can be configured 19.79 Hz and provides simultaneous 50 Hz and 60 Hz rejection with a gain of 1 or 16 allowing full-scale input signal ranges of at this update rate. At this update rate, 18-bit p-p resolution can ±2.56 V or ±160 mV from a +2.5 V differential reference input. be obtained. It also contains two 200 mA integrated current sources. The part operates from a single 3 V or 5 V supply. When oper- The AD7783 has an extremely simple, read-only digital inter- ating from 3 V supplies, the power dissipation for the part is face that can be operated in master mode or slave mode. 3.9 mW. The AD7783 is available in a 16-lead TSSOP. There are no on-chip registers to be programmed. The input Another part in the AD778x family is the AD7782. It is similar signal range and current source selection are configured using to the AD7783 except it has no integrated current sources and two external pins. two differential input channels. REV. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise
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Document Outline FEATURES INTERFACE POWER ON-CHIP FUNCTIONS APPLICATIONS FUNCTIONAL BLOCK DIAGRAM BASIC CONNECTION DIAGRAM GENERAL DESCRIPTION SPECIFICATIONS TIMING CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS ORDERING GUIDE PIN CONFIGURATION PIN FUNCTION DESCRIPTIONS Typical Performance Characteristics ADC CIRCUIT INFORMATION Overview NOISE PERFORMANCE DIGITAL INTERFACE MASTER MODE (MODE = 0) SLAVE MODE (MODE = 1) CIRCUIT DESCRIPTION Analog Input Channel Programmable Gain Amplifier Bipolar Configuration/Output Coding Excitation Currents Crystal Oscillator Reference Input Grounding and Layout OUTLINE DIMENSIONS Revision History