AD7783 Read-Only, Pin-Configured, 24-bit Sigma-Delta ADC with Excitation Current Sources

The AD7783 is a complete analog front end for low frequency measurement applications. The 24-bit sigma-delta ADC contains one fully differential input channel that can be configured with a gain of 1 or 16 allowing full-scale input signal ranges of ±2.56 V or ±160 mV from a +2.5 V differential reference input. It also contains two 200 mA integrated current sources.

The AD7783 has an extremely simple, read-only digital interface that can be operated in master mode or slave mode. There are no on-chip registers to be programmed. The input signal range and current source selection are configured using two external pins.

The device operates from a 32.768 kHz crystal with an on-chip PLL generating the required internal operating frequency. The output data rate from the part is fixed via the master clock at 19.79 Hz and provides simultaneous 50 Hz and 60 Hz rejection at this update rate. At this update rate, 18-bit p-p resolution can be obtained.

The part operates from a single 3 V or 5 V supply. When operating from 3 V supplies, the power dissipation for the part is 3.9 mW. The AD7783 is available in a 16-lead TSSOP.

Another part in the AD778x family is the AD7782. It is similar to the AD7783 except it has no integrated current sources and two differential input channels.

Applications

Sensor Measurement
Industrial Process Control
Temperature Measurement
Pressure Measurement
Weigh Scales
Portable Instrumentation

Features and Benefits

Single-Channel, 24-Bit Σ-Δ ADC
Pin Configurable (No Programmable Registers)
- ISOURCE SelectTM
- Pin Programmable Input
Ranges (±2.56 V or ±160 mV)
Fixed 19.79 Hz Update Rate
Simultaneous 50 Hz and 60 Hz Rejection
24-Bit No Missing Codes
18.5-Bit p-p Resolution (±2.56 V Range)
16.5-Bit p-p Resolution (±160 mV Range)

INTERFACE
-- Master or Slave Mode of Operation
Slave Mode
-- 3-Wire Serial
-- SPI®, QSPI™, MICROWIRE™, and DSP-Compatible
-- Schmitt Trigger on SCLK
POWER
-- Specified for Single 3 V
and 5 V Operation
-- Normal: 1.3 mA @ 3 V
-- Power-Down: 9 µA
ON-CHIP FUNCTIONS
-- Rail-to-Rail Input Buffer and PGA

Analog to Digital Converters

A/D Converters

Data Sheets

Document	note
AD7783: Read-Only, Pin Configured 24-Bit Σ-Δ ADC With Excitation Current Sources Data Sheet (Rev. C)	PDF 217 kB

Application Notes

Document	note
AN-610: The PGA on Sigma-Delta ADCs (Rev. A)	PDF 152 kB
AN-609: Chopping on Sigma-Delta ADCs (Rev. 0)	PDF 232 kB
AN-608: Input Buffers on Sigma-Delta ADCs (Rev. 0)	PDF 284 kB
AN-202: An IC Amplifier User’s Guide to Decoupling, Grounding, and Making Things Go Right for a Change (Rev. B)	PDF 76.97 K
AN-968: Current Sources: Options and Circuits (Rev. 0)	PDF 131 kB
AN-311: How to Reliably Protect CMOS Circuits Against Power Supply Overvoltaging	PDF 217 kB
AN-607: Selecting a Low Bandwidth (<15 kSPS) Sigma-Delta ADC (Rev. E)	PDF 222 kB
AN-615: Peak-to-Peak Resolution Versus Effective Resolution (Rev. 0)	PDF 70 kB
AN-611: 50 Hz/60Hz Rejection on Sigma-Delta ADCs (Rev. 0)	PDF 360 kB
AN-397: Electrically Induced Damage to Standard Linear Integrated Circuits:	PDF 149 kB