ADS8668IDBT

The ADS8664 and ADS8668 are 4-channel and 8-channel integrated data acquisition systems based on 12-bit successive approximation register (SAR) analog-to-digital converters (ADCs), with an operating throughput of up to 500 kSPS. These devices feature an integrated analog front-end circuit for each input channel (with overvoltage protection up to ±20 V), a 4-channel or 8-channel multiplexer supporting both automatic and manual scan modes, and an on-chip 4.096 V reference voltage with low temperature drift. These devices are powered by a single 5 V analog supply. Each input channel can support true bipolar input ranges (±10.24 V, ±5.12 V, ±2.56 V, ±1.28 V, and ±0.64 V) and unipolar input ranges (0 V to 10.24 V, 0 V to 5.12 V, 0 V to 2.56 V, and 0 V to 1.28 V). The gain of the analog front-end is precisely adjusted across all input ranges to ensure high DC accuracy. The input range can be programmed via software, and the input range selection for each channel is independent. The device provides a constant resistive input impedance of 1 MΩ regardless of the selected input range. The ADS8664 and ADS8668 offer a simple serial interface compatible with the Serial Peripheral Interface (SPI) for the digital host, and support daisy-chaining multiple devices. The digital supply can provide voltages in the range of 1.65 V to 5.25 V, enabling direct connection to various host controllers.

Applications

• Power Automation
• Protection Relays
• PLC Analog Input Modules

Key features

• 12-bit ADC with integrated analog front end
• 4-channel, 8-channel multiplexer with auto and manual scan
• Per-channel programmable inputs: ±10.24V, ±5.12V, ±2.56V, ±1.28V, ±0.64V, 10.24V, 5.12V, 2.56V, 1.28V
• 5V analog supply, 1.65V to 5V I/O supply
• Constant resistive input impedance: 1MΩ
• Input overvoltage protection: up to ±20V
• Low-drift on-chip 4.096V voltage reference
• Total throughput: 500kSPS
• DNL: ±0.2 LSB; max INL: ±0.2 LSB
• Low drift in gain error and offset error
• SNR: 73.8dB; THD: –95dB
• Low power consumption: 65mW
• AUX input → direct connection to ADC input
• ALARM → per-channel high/low threshold
• SPI-compatible interface with daisy-chain support
• Industrial temperature range: -40°C to 125°C
• TSSOP-38 package (9.7mm×4.4mm)