GENERAL DESCRIPTION

The AD7606/AD7606-6/AD7606-4 are 16-bit, simultaneous sampling, analog-to-digital data acquisition systems (DAS) with eight, six, and four channels, respectively. Each part contains analog input clamp protection, a second-order antialiasing filter, a track-and-hold amplifier, a 16-bit charge redistribution successive approximation analog-to-digital converter (ADC), a flexible digital filter, a 2.5 V reference and reference buffer, and high speed serial and parallel interfaces.

The AD7606/AD7606-6/AD7606-4 operate from a single 5 V supply and can accommodate ±10 V and ±5 V true bipolar input signals while sampling at throughput rates up to 200 kSPS for all channels. The input clamp protection circuitry can tolerate voltages up to ±16.5 V. The AD7606 has 1 MΩ analog input impedance regardless of sampling frequency. The single supply operation, on-chip filtering, and high input impedance eliminate the need for driver op amps and external bipolar supplies. The AD7606/AD7606-6/ AD7606-4 antialiasing filter has a 3 dB cutoff frequency of 22 kHz and provides 40 dB antialias rejection when sampling at 200 kSPS. The flexible digital filter is pin driven, yields improvements in SNR, and reduces the 3 dB bandwidth.

 

FEATURES

8/6/4 simultaneously sampled inputs

True bipolar analog input ranges: ±10 V, ±5 V

Pin to pin compatible with the state-of-the-art AD7606B

Single 5 V analog supply and 2.3 V to 5 V VDRIVE

Fully integrated data acquisition solution

Analog input clamp protection

Input buffer with 1 MΩ analog input impedance

Second-order antialiasing analog filter

On-chip accurate reference and reference buffer

16-bit ADC with 200 kSPS on all channels

Oversampling capability with digital filter

Flexible parallel/serial interface

SPI/QSPI™/MICROWIRE™/DSP compatible

Performance

7 kV ESD rating on analog input channels

95.5 dB SNR, −107 dB THD

±0.5 LSB INL, ±0.5 LSB DNL

Low power: 100 mW

Standby mode: 25 mW

Temperature range: −40°C to +85°C

64-lead LQFP package

 

APPLICATIONS

Power-line monitoring and protection systems

Multiphase motor control

Instrumentation and control systems

Multiaxis positioning systems

Data acquisition systems (DAS)

 

THEORY OF OPERATION

CONVERTER DETAILS

The AD7606/AD7606-6/AD7606-4 are data acquisition systems that employ a high speed, low power, charge redistribution, successive approximation analog-to-digital converter (ADC) and allow the simultaneous sampling of eight/six/four analog input channels. The analog inputs on the AD7606/AD7606-6/AD7606-4 can accept true bipolar input signals. The RANGE pin is used to select either ±10 V or ±5 V as the input range. The AD7606/AD7606-6/AD7606-4 operate from a single 5 V supply.

The AD7606/AD7606-6/AD7606-4 contain input clamp protection, input signal scaling amplifiers, a second-order anti-aliasing filter, track-and-hold amplifiers, an on-chip reference, reference buffers, a high speed ADC, a digital filter, and high speed parallel and serial interfaces. Sampling on the AD7606/AD7606-6/AD7606-4 is controlled using the CONVST signals.

ANALOG INPUT

Analog Input Ranges

The AD7606/AD7606-6/AD7606-4 can handle true bipolar, singleended input voltages. The logic level on the RANGE pin determines the analog input range of all analog input channels. If this pin is tied to a logic high, the analog input range is ±10 V for all channels. If this pin is tied to a logic low, the analog input range is ±5 V for all channels. A logic change on this pin has an immediate effect on the analog input range; however, there is typically a settling time of approximately 80 μs, in addition to the normal acquisition time requirement. The recommended practice is to hardwire the RANGE pin according to the desired input range for the system signals.

During normal operation, the applied analog input voltage should remain within the analog input range selected via the RANGE pin. A RESET pulse must be applied after power up to ensure the analog input channels are configured for the range selected.

When in a power-down mode, it is recommended to tie the analog inputs to GND. Per the Analog Input Clamp Protection section, the overvoltage clamp protection is recommended for use in transient overvoltage conditions and should not remain active for extended periods. Stressing the analog inputs outside of the conditions mentioned here may degrade the bipolar zero code error and THD performance of the AD7606/AD7606-6/AD7606-4.