1 Features

1? Analog features

– Programmable-gain analog front end for LVDT

sensors

– Excitation waveform generator and amplifier

– Dual 24-bit ADC with amplitude and phase

demodulators

– 24-bit auxilary ADC

– On-chip internal temperature sensor

– 14-bit output DAC with programmable gain

– Built-in diagnostics

? Digital features

– ARM? Cortex?-M0 microcontroller

– 16KB ferroelectric RAM (FRAM) program

memory

– 2KB general-pupose RAM

– 512B RAM waveform-generator look-up table

– 8-MHz on-chip oscillator

? Peripheral features

– Serial peripheral interface (SPI)

– One-wire interface (OWI)

– Ratiometric and absolute voltage output

? General features

– Operational supply range: 3.5 V to 30 V

– Ambient temperature range: –40°C to +125°C

– DMOS gate controller for extended supply

range >30 V

2 Applications

? Position sensor signal conditioning

? Linear variable differential transformer (LVDT)

? Rotational variable differential transformer (RVDT)

? Resolver

? RLC measurement

3 Description

The PGA970 is a highly integrated system-on-chip

LVDT sensor-signal conditioner with advanced signalprocessing

capabilities. It contains a three-channel,

low-noise, programmable-gain, analog front end that

allows direct connection to the sense element,

followed by three independent 24-bit delta-sigma

ADCs.

Further, the device contains a digital signaldemodulation

block that interfaces to an integrated

ARM-Cortex M0 MCU, allowing implementation of

custom sensor-compensation algorithms stored in the

device nonvolatile memory. External system

communication is achieved by using any of the SPI,

OWI, GPIO, or PWM digital interfaces. Analog output

is supported through a 14-bit DAC and

programmable-gain amplifier offering reference or

absolute-voltage output. Sensing-element excitation

is achieved by the use of an integrated waveform

generator and waveform amplifier. The waveform

signal data is user-defined and stored in a designated

RAM memory area.

Besides the primary functional components, the

PGA970 is equipped with additional support circuitry.

The device diagnostics, sensor diagnostics, and

integrated temperature sensor provide protection and

information about the integrity of the overall system

and sensing element. The device also includes a

gate-controller circuit which when used with an

external depletion MOSFET can regulate the device

supply voltage in systems where the supply voltage

exceeds 30 V.