AD7822 3 V/5 V, 2 MSPS, 8-Bit, 1-/4-/8-Channel Sampling ADCs

Fast Conversion Time. The AD7822/AD7825/AD7829 have a conversion time of 420 ns. Faster conversion times maximize the DSP processing time in a real-time system. Analog Input Span Adjustment. The VMID pin allows the user to offset the input span. This feature can reduce the requirements of single-supply op amps and take into account any system offsets. FPBW (Full Power Bandwidth) of Track-and-Hold. The track-and-hold amplifier has an excellent high frequency performance. The AD7822/AD7825/AD7829 are capable of converting full-scale input signals up to a frequency of 10 MHz. This makes the parts ideally suited to subsampling applications. Channel Selection. Channel selection is made without the necessity of writing to the part. Applications Data acquisition systems, DSP front ends Disk drives Mobile communication systems, subsampling applications

The AD7822/AD7825/AD7829 are high speed, 1-, 4-, and 8-channel, microprocessor-compatible, 8-bit analog-to-digital converters with a maximum throughput of 2 MSPS. The AD7822/ AD7825/AD7829 contain an on-chip reference of 2.5 V (2% tolerance); a track-and-hold amplifier; a 420 ns, 8-bit half-flash ADC; and a high speed parallel interface. The converters can operate from a single 3 V ± 10% and 5 V ± 10% supply.

The AD7822/AD7825/AD7829 combine the convert start and power-down functions at one pin, that is, the CONVST pin. This allows a unique automatic power-down at the end of a conversion to be implemented. The logic level on the CONVST pin is sampled after the end of a conversion when an EOC (end of conversion) signal goes high. If it is logic low at that point, the ADC is powered down. The AD7822 and AD7825 also have a separate power-down pin (see the Operating Modes section).

The parallel interface is designed to allow easy interfacing to microprocessors and DSPs. Using only address decoding logic, the parts are easily mapped into the microprocessor address space. The EOC pulse allows the ADCs to be used in a stand-alone manner (see the Parallel Interface section.)

The AD7822 and AD7825 are available in 20-lead and 24-lead, 0.3" wide, plastic dual in-line packages (PDIP); 20-lead and 24-lead standard small outline packages (SOIC); and 20-lead and 24-lead thin shrink small outline packages (TSSOP). The AD7829 is available in a 28-lead, 0.6" wide PDIP; a 28-lead SOIC; and a 28-lead TSSOP.

Product Highlights

Features and Benefits
  • 8-bit half-flash ADC with 420 ns conversion time
  • 1, 4 and 8 Single-Ended Analog Input Channels Available with Input Offset Adjust
  • On-Chip Track-and-Hold
  • SNR Performance Given for Input Frequencies Up to 10 MHz
  • Automatic Power-Down at the End of Conversion
  • On-Chip Reference (2.5 V)
  • Wide Operating Supply Range
    3 V ± 10% and 5 V ± 10%
  • Input Ranges:
    0 V to 2 V p-p, VDD = 3 V ± 10%
    0 V to 2.5 V p-p, VDD = 5 V ± 10%
  • Flexible Parallel Interface with EOC Pulse to Allow Stand-Alone Operation
Analog to Digital Converters
Data Sheets
Documentnote
AD7822/AD7825/AD7829: 3 V/5 V, 2 MSPS, 8-Bit, 1-/4-/8-Channel Sampling ADCs Data Sheet (Rev. C)PDF 518 kB
Application Notes
Documentnote
AN-215: Designer's Guide to Flash-ADC Testing, Part 1, 2 & 3PDF 1596 kB
AN-592: Application Considerations for the Convert Start Input (CONVST Bar) of the AD7822/AD7825/AD7827/AD7829 (Rev. 0)PDF 37 kB
Order Information
Part NumberPackagePacking QtyTemp RangePrice 100-499Price 1000+RoHS
AD7822BNZ Production20 ld PDIPOTH 18-45 to 85C5.924.57Y
AD7822BR Production20 ld SOIC - WideOTH 37-45 to 85C00N
AD7822BR-REEL Production20 ld SOIC - WideREEL 1000-45 to 85C00N
AD7822BRU Production20 ld TSSOPOTH 75-40 to 85C00N
AD7822BRU-REEL Production20 ld TSSOPREEL 2500-40 to 85C00N
AD7822BRU-REEL7 Production20 ld TSSOPREEL 1000-40 to 85C00N
AD7822BRUZ Production20 ld TSSOPOTH 75-40 to 85C5.234.04Y
AD7822BRZ Production20 ld SOIC - WideOTH 37-40 to 85C5.234.04Y
AD7822BRZ-REEL Production20 ld SOIC - WideREEL 1000-40 to 85C04.04Y
AD7822BRZ-REEL7 Production20 ld SOIC - WideREEL 400-40 to 85C04.04Y
Reference Materials
AD7822/AD7825/AD7829: 3 V/5 V, 2 MSPS, 8-Bit, 1-/4-/8-Channel Sampling ADCs Data Sheet (Rev. C) ad7822
AN-215: Designer's Guide to Flash-ADC Testing, Part 1, 2 & 3 ad7822
AN-215: Flash型ADC测试指南第一部分Flash型ADC是高速转换的基础 (Rev. 0) ad7822
AN-592: Application Considerations for the Convert Start Input (CONVST Bar) of the AD7822/AD7825/AD7827/AD7829 (Rev. 0) ad7822
MS-2210:高速ADC的电源设计 ad9861