3 V/5 V, 2 MSPS, 8-Bit, 8-Channel ADC

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

The AD7829-1 combines 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, and if it is logic low at that point, the ADC is powered down. 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 AD7829-1 is available in a 28-lead, wide body, small outline IC (SOICW) and a 28-lead thin shrink small outline package (TSSOP).

PRODUCT HIGHLIGHTS

* Fast Conversion Time. The AD7829-1 has 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 excellent high frequency

performance. The AD7829-1 is capable of converting fullscale

input signals up to a frequency of 10 MHz, making

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

* 8-bit half-flash ADC with 420 ns conversion time

* Eight single-ended analog input channels

Available with input offset adjust

* SNR performance given for input frequencies up to 10 MHz

* Automatic power-down at the end of conversion

* Flexible parallel interface with EOC pulse to allow stand-alone operation