Analog Devices

The AD7864 is a high speed, low power, 4-channel, simulta-neous sampling 12-bit analog-to-digital converter (ADC) that operates from a single 5 V supply. The part contains a 1.65 μs successive approximation ADC, four track-and-hold amplifiers, a 2.5 V reference, an on-chip clock oscillator, signal conditioning circuitry, and a high speed parallel interface. The input signals on four channels sample simultaneously preserving the relative phase information of the signals on the four analog inputs. The part accepts analog input ranges of ±10 V, ±5 V (AD7864-1), 0 V to +2.5 V, 0 V to +5 V (AD7864-2), and ±2.5 V (AD7864-3).Any subset of the four channels can be converted to maximize the throughput rate on the selected sequence. Select the channels to convert via hardware (channel select input pins) or software (programming the channel select register).A single conversion start signal(CONVST)simultaneously places all the track-and-holds into hold and initiates a conversion sequence for the selected channels. TheEOCsignal indicates the end of each individual conversion in the selected conversion sequence. The BUSY signal indicates the end of the conversion sequence.Data is read from the part by a 12-bit parallel data bus using the standardCSandRDsignals. Maximum throughput for a single channel is 500 kSPS. For all four channels, the maximum throughput is 130 kSPS for the read-during-conversion sequence operation. The throughput rate for the read-after-conversion sequence operation depends on the read cycle time of the processor. See the Timing and Control section. The AD7864 is available in a small (0.3 square inch area) 44-lead MQFP.

The AD7865 is a fast, low power, four-channel simultaneous sampling 14-bit A/D converter that operates from a single +5 V supply. The part contains a 2.5 µs successive approximation ADC, four track/hold amplifiers, 2.5 V reference, on chip clock oscillator, signal conditioning circuitry and a high speed parallel interface. The input signals on four channels are sampled simultaneously thus preserving the relative phase information of the signals on the four analog inputs. The part accepts analog input ranges of ±10 V, ±5 V or ±2.5 V. Overvoltage protection on the analog inputs for the part allows the input voltage to go to ±20 V without damaging the parts or affecting a conversion in progress.

The AD7866 is a dual 12-bit high-speed, low power, successive-approximation ADC. The part operates from a single 2.7 V to 5.25 V power supply and features throughput rates up to 1 MSPS. The device contains two ADCs, each preceded by a low-noise, wide bandwidth track/hold amplifier, which can handle input frequencies in excess of 10 MHz.The conversion process and data acquisition are controlled using standard control inputs allowing easy interfacing to microprocessors or DSPs. The input signal is sampled on the falling edge ofCSand conversion is also initiated at this point. The conversion time is determined by the SCLK frequency. There are no pipelined delays with the part.The AD7866 uses advanced design techniques to achieve very low power dissipation at high throughput rates. With 3 V supplies and 1 MSPS throughput rate, the part consumes a maximum of 3.8 mA. With 5 V supplies and 1 MSPS, the current consumption is a maximum of 4.8 mA. The part also offers flexible power/throughput rate management when operating in sleep mode.The analog input range for the part can be selected to be a 0 V to VREFrange or a 2 × VREFrange with either straight binary or twos complement output coding. The AD7866 has an on-chip 2.5 V reference that can be overdriven if an external reference is preferred. Each on-board ADC can also be supplied with a separate individual external reference.The AD7866 is available in a 20-lead thin shrink small outline (TSSOP) package.PRODUCT HIGHLIGHTSThe AD7866 features two complete ADC functions, allowing simultaneous sampling and conversion of two channels. Each ADC has a 2-channel input multiplexer. The conversion result of both channels is available simultaneously on separate data lines, or may be taken on one data line if only one serial port is available.High Throughput with Low Power Consumption—The AD7866 offers a 1 MSPS throughput rate with 11.4 mW maximum power consumption when operating at 3 V.Flexible Power/Throughput Rate Management—The conversion rate is determined by the serial clock, allowing the power consumption to be reduced as the conversion time is reduced through a SCLK frequency increase. Power efficiency can be maximized at lower throughput rates if the part enters sleep during conversions.No Pipeline Delay—The part features two standard successive approximation ADCs with accurate control of the sampling instant via aCSinput and once off conversion control.

The AD7871 /AD7872are fast, complete, 14-bit analog-to-digital converters (ADC). They consist of a track-and-hold amplifier, successive approximation ADC, 3 V buried Zener reference, and versatile interface logic. The ADC features a self-contained, laser trimmed internal clock, so no external clock timing components are required. The on-chip clock may be overridden to synchronize ADC operation to the digital system for minimum noise.The AD7871 offers a choice of three data output formats: a single, parallel, 14-bit word; two 8-bit bytes or a 14-bit serial data stream. The AD7872 is a serial output device only. The two parts are capable of interfacing to all modern microprocessors and digital signal processors.The AD7871 / AD7872 operate from ±5 V power supplies, accept bipolar input signals of ±3 V and can convert full power signals up to 41.5 kHz.In addition to the traditional dc accuracy specifications, the AD7871 / AD7872 are also fully specified for dynamic performance parameters including distortion and signal-to-noise ratio.Both devices are fabricated in Analog Devices, Inc., LC2MOS mixed technology process. The AD7871 is available in 28-pin PDIP, PLCC, and CERDIP packages. The AD7872 is available in a 16-pin PDIP, CERDIP, and SOIC packages.

TheAD7871/ AD7872 are fast, complete, 14-bit analog-to-digital converters (ADC). They consist of a track-and-hold amplifier, successive approximation ADC, 3 V buried Zener reference, and versatile interface logic. The ADC features a self-contained, laser trimmed internal clock, so no external clock timing components are required. The on-chip clock may be overridden to synchronize ADC operation to the digital system for minimum noise.The AD7871 offers a choice of three data output formats: a single, parallel, 14-bit word; two 8-bit bytes or a 14-bit serial data stream. The AD7872 is a serial output device only. The two parts are capable of interfacing to all modern microprocessors and digital signal processors.The AD7871 / AD7872 operate from ±5 V power supplies, accept bipolar input signals of ±3 V and can convert full power signals up to 41.5 kHz.In addition to the traditional dc accuracy specifications, the AD7871/AD7872 are also fully specified for dynamic performance parameters including distortion and signal-to-noise ratio.Both devices are fabricated in Analog Devices, Inc., LC2MOS mixed technology process. The AD7871 is available in 28-pin PDIP, PLCC, and CERDIP packages. The AD7872 is available in a 16-pin PDIP, CERDIP, and SOIC packages.APPLICATIONSDigital signal processingHigh speed modemsSpeech recognition and synthesisSpectrum analysisDSP servo control

TheAD7870/AD7875/ AD7876 is a fast, complete, 12-bit A/D converter. It consists of a track/hold amplifier, 8 µs successive approximation ADC, 3 V buried Zener reference and versatile interface logic. The ADC features a self-contained internal clock which is laser trimmed to guarantee accurate control of conversion time. No external clock timing components are required; the on-chip clock may he overridden by an external clock if required.The parts offer a choice of three data output formats: a single, parallel, 12-bit word; two 8-bit bytes or serial data. Fast bus access times and standard control inputs ensure easy interfacing to modern microprocessors and digital signal processors.All parts operate from ±5 V power supplies. The AD7870 and AD7876 accept input signal ranges of ±3 V and ±10 V, respectively, while the AD7875 accepts a unipolar 0 V to +5 V input range. The parts can convert full power signals up to 50 kHz.The AD7870 / AD7875 / AD7876 feature dc accuracy specifications such as linearity, full-scale and offset error. In addition, the AD7870 and AD7875 are fully specified for dynamic performance parameters including distortion and signal-to-noise ratio.The parts are available in a 24-pin, 0.3 inch-wide, plastic or hermetic dual-in-line package (DIP). The AD7870 and AD7875 are available in a 28-pin plastic leaded chip carrier (PLCC), while the AD7876 is available and in a 24-pin small outline (SOIC) package.PRODUCT HIGHLIGHTSComplete 12-bit ADC on a chip.The AD7870 / AD7875/ AD7876 provide all the functions necessary for analog-to-digital conversion and combine a 12-bit ADC with internal clock, track-and-hold amplifier and reference on a single chip.Dynamic specifications for DSP users.The AD7870 and AD7875 are fully specified and tested for ac parameters, including signal-to-noise ratio, harmonic distortion and intermodulation distortion.Fast microprocessor interface.Data access times of 57 ns make the parts compatible with modern 8-bit and 16-bit microprocessors and digital signal processors. Key digital timing parameters are tested and guaranteed over the full operating temperature range.