AD2S93

The AD2S93 is a complete 14-bit resolution tracking LVDT-todigital converter. A Type II tracking loop is employed to track the AB input and produce a digital output equal to (AB)/ (REF/2), where REF is a fixed amplitude ac reference phase coherent with the AB input. This allows the measurement of any 2-, 3-, 4- and 5-wire LVDT or linear amplitude modulated input.

The operating frequency range of AD2S93 is from 360 Hz to 10 kHz with user definable bandwidth set externally within a range of 45 Hz to 1250 Hz.

The AD2S93 has a 16-bit serial output. The MSB (LOS), read first, indicates a loss of the signal A, B, or reference inputs to theconverter or transducer. The second and third MSBs are flags indicating whether [REF/2 (UNR) £ AB £ +REF/2 (OVR]) is outside the linear operating range of the converter. The displacement data is presented as 13-bit offset binary giving a ±12- bit operating range. LOS, OVR and UNR are pinned out on the device, in addition a NULL flag is available which is set when (AB) = 0.

Absolute displacement information of AD2S93 is accessed when CS is taken LO followed by the application of an external clock (SCLK) with a maximum rate of 2 MHz. Data is read MSB first. When CS is high the DATA output is high impedance; this allows daisy chaining of more than one converter onto a common bus.