Features: 8-/10-Channel, High Resolution - ADCs
AD7708 Has 16-Bit Resolution
AD7718 Has 24-Bit Resolution
Factory-Calibrated
Single Conversion Cycle Setting
Programmable Gain Front End
Simultaneous 50 Hz and 60 Hz Rejection
VREF Select(TM) Allows Absolute and Ratiometric
Measurement Capability
Operation Can Be Optimized for
Analog Performance (CHOP = 0) or
Channel Throughput (CHOP = 1)
INTERFACE
3-Wire Serial
SPI TM, QSPI TM, MICROWIRETM , and DSP-Compatible
Schmitt Trigger on SCLK
POWER
Specified for Single 3 V and 5 V Operation
Normal: 1.28 mA Typ @ 3 V
Power-Down: 30 A (32 kHz Crystal Running)
On-Chip Functions
Rail-to-Rail Input Buffer and PGA
2-Bit Digital I/O Port
APPLICATIONS
Industrial Process Control
Instrumentation
Pressure Transducers
Portable Instrumentation
Smart TransmittersPinout
SpecificationsAVDD to AGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ... . .. 0.3 V to +7 V
AVDD to DGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . .. 0.3 V to +7 V
DVDD to AGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 0.3 V to +7 V
DVDD to DGND . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . .. . . 0.3 V to +7 V
AGND to DGND . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . .. . .. .0.05 V to +0.05 V
AVDD to DVDD . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . ... . . 5 V to +5 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
Total AIN/REFIN Current (Indefinite) . . . . . . .. . . . . . . . .. . . . . . .. .. .. . . . . 30 mA
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 . . . . . . . . . . . . . . . . . . .. .. . . .. . . .. . 40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . . . . .. . . . . .. . . . .. . . . 65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. .. ... . .. .. . .150°C
SOIC Package
JA Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 71.4°C/W
JC Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 23°C/W
TSSOP Package
JA Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... .. . . . .. . 97.9°C/W
JC Thermal Impedance . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . . .. . 14°C/W
Lead Temperature, Soldering
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . ... . . . . .. . .. . . . . .. . . 215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . . . .. .. . . . . . 220°C
| Resolution (Bits) |
16bit |
| T-Put Rate |
1.365kSPS |
| # Chan |
10 |
| Supply V |
Single(+3),Single(+3.3),Single(+5) |
| Pwr Diss (max) |
8.75mW |
| Interface |
Ser,SPI |
| Ain Range |
(2Vref/PGA Gain) p-p |
| SNR (dB) |
112dB |
| Pkg Type |
SOIC,SOP |
DescriptionThe AD7708/AD7718 are complete analog front-ends for low frequency measurement applications. The AD7718 contains a 24-bit - ADC with PGA and can be configured as 4/5 fully-differential input channels or 8/10 pseudo-differential input channels. Two pins on the device are configurable as analog inputs or reference inputs.
The AD7708 is a 16-bit version of the AD7718. Input signal ranges from 20 mV to 2.56V can be directly converted using these ADCs. Signals can be converted directly from a transducer without the need for signal conditioning. The device operates from a 32 kHz crystal with an on-board PLL generating the required internal operating frequency. The output data rate from the part is software programmable.
The peak-to-peak resolution from the part varies with the programmed gain and output data rate. 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 3.84 mW typ. Both parts are pin-for-pin compatible allowing an upgradable path from 16 to 24 bits without the need for hardware modifica-tions. The AD7708/AD7718 are housed in 28-lead SOIC and TSSOP packages.
AD7708 Data Sheet
