High-Speed, 8-Channel, 8-Bit ADC with Simultaneous Track/Holds and Reference

The MAX155/MAX156 are high-speed, 8-bit, multichannel analog-to-digital converters (ADCs) with simultaneous track/holds (T/Hs) to eliminate timing differences between input channel samples. The MAX155 has 8 analog input channels and the MAX156 has 4 analog input channels. Each channel has its own T/H, and all T/Hs sample at the same instant. The ADC converts a channel in 3.6µs and stores the result in an internal 8x8 RAM. The MAX155/MAX156 also feature a 2.5V internal reference and power-down capability, providing a complete, sampling data-acquisition system.

When operating from a single +5V supply, the MAX155/MAX156 perform either unipolar or bipolar, single-ended or differential conversions. For applications requiring wider dynamic range or bipolar conversions around ground, the VSS supply pin may be connected to -5V.

Conversions are initiated with a pulse to the active-low WR pin, and data is accessed from the ADC’s RAM with a pulse to the active-low RD pin. A bidirectional interface updates the channel configuration and provides output data. The ADC may also be wired for output-only operation.The MAX155 comes in 28-pin PDIP and wide SO packages, and the MAX156 comes in 24-pin narrow PDIP and 28-pin wide SO packages.

Applications

* AC Power Meters * DSP Analog Input * Phase-Sensitive Data Acquisition * Portable Data Loggers * Vibration and Waveform Analysis

* 8 Simultaneously Sampling Track/Hold Inputs

* 3.6µs Conversion Time Per Channel

* Unipolar or Bipolar Input Range

* Single-Ended or Differential Inputs

* Mixed Input Configurations Possible

* 2.5V Internal Reference

* Single +5V or Dual ±5V Supply Operation