AD7714

Features:

Charge Balancing ADC
24 Bits No Missing Codes
0.0015% Nonlinearity
Five-Channel Programmable Gain Front End
Gains from 1 to 128
Can Be Configured as Three Fully Differential
Inputs or Five Pseudo-Differential Inputs
Three-Wire Serial Interface
SPI^(TM), QSPI^(TM), MICROWIRE^(TM) and DSP Compatible
3 V (AD7714-3) or 5 V (AD7714-5) Operation
Low Noise (<150 nV rms)
Low Current (350? mA typ) with Power-Down (5 mA typ)
AD7714Y Grade:
+2.7 V to 3.3 V or +4.75 V to +5.25 V Operation
0.0010% Linearity Error
408C to +1058C Temperature Range
Schmitt Trigger on SCLK and DIN
Low Current (226? mA typ) with Power-Down (4 mA typ)
Lower Power Dissipation than Standard AD7714
Available in 24-Lead TSSOP Package
Low-Pass Filter with Programmable Filter Cutoffs
Ability to Read/Write Calibration Coefficients




Application

Portable Industrial Instruments
Portable Weigh Scales
Loop-Powered Systems
Pressure Transducers




Pinout








Specifications



AVDD to AGND . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to +7 V
AVDD to DGND . . . . . . . . . . . . . . . . . . . . . . . . 0.3V to + 7 V
DVDD to AGND . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to +7 V
DVDD to DGND . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to +7 V
Analog Input Voltage to AGND . . . . . 0.3 V to AVDD + 0.3 V
Reference Input Voltage to AGND . . . 0.3 V to AVDD + 0.3 V
Digital Input Voltage to DGND . . . . . 0.3 V to DVDD + 0.3 V
Digital Output Voltage to DGND . . . . 0.3 V to DVDD + 0.3 V
Operating Temperature Range
Commercial (A Version) .. . . . . . . . . . . . . . 40C to +85C
Extended (Y Version). . . . . . . . .. . . . . . . . 40C to +105C
Storage Temperature Range . . . . . . . . . . . . 65C to +150C
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . .+150 C
Plastic DIP Package, Power Dissipation . . . . . . . . . . 450 mW
q JA Thermal Impedance. . . . . . . . . . . . . . . . . . . . . 105 C/W
Lead Temperature (Soldering, 10 sec). . . . . . . . . . . .+260 C
SOIC Package, Power Dissipation . . . . . . . . . . . . . . .450 mW
q JA Thermal Impedance. . . . . . . . . . . . . . . . . . . . . . 75 C/W
Lead Temperature, Soldering
Vapor Phase (60 sec). . . . . . . . . . . . . . . . . . . . . . . +215 C
Infrared (15 sec). .. . . . . . . . . . . . . . . . . . . . . . . . . +220 C
SSOP Package, Power Dissipation . . . . . . . . . . . . . . . .450 mW
q JA Thermal Impedance . . . . . . . . . . . . . . . . . . . . 109 C/W
Lead Temperature, Soldering
Vapor Phase (60 sec). . . . . . . . . . . . . . . . . . . . . . . . +215 C
Infrared (15 sec) . . . . . .. . . . . . . . . . . . . . . . . . . . . . +220 C
TSSOP Package, Power Dissipation . . . . . . . . . . . . . .450 mW
q JA Thermal Impedance. . . . . . . . . . . . . . . . . . . . . 128 C/W
Lead Temperature, Soldering
Vapor Phase (60 sec). . . . . . . . . . . .. . .. . . . . . . . . . . +215 C
Infrared (15 sec) . . . . . . . . . . . . .. . . . . . . . . . . . . . . . +220 C




Description

The AD7714 is a complete analog front end for low-frequency measurement applications. The device accepts low level signals directly from a transducer and outputs a serial digital word. It employs a sigma-delta conversion technique to realize up to 24 bits of no missing codes performance. The input signal is applied to a proprietary programmable gain front end based around an analog modulator. The modulator output is processed by an on- chip digital filter. The first notch of this digital filter can beprogrammed via the on-chip control register allowing adjust-ment of the filter cutoff and settling time.

The part features three differential analog inputs (which can also be configured as five pseudo-differential analog inputs) as well as a differential reference input. It operates from a single supply (+3 V or +5 V). The AD7714 thus performs all signal conditioning and conversion for a system consisting of up to five channels.