Smart Grid Solutions Guide - Maxim

Power-grid monitoringFeatured productsDigital potentiometers automate calibration of line-monitoring instrumentsMAX5422/MAX5423/MAX5424The MAX5422/MAX5423/MAX5424 nonvolatile, linear-taper digitalpotentiometers perform the function of a mechanical potentiometer,but replace the mechanics with an integrated resistor stringcontrolled with a simple 3-wire, SPI-compatible digital interface.This design minimizes board space and reduces interconnectioncomplexity in many applications. Each device performs the samefunction as a discrete potentiometer or variable resistor and has256 tap points.Benefits••Optimize board layout––Tiny 3mm x 3mm TDFN package••Retain calibration even during powercycling––Nonvolatile memory restores the wiperposition during power-upThese digital potentiometers feature internal nonvolatile (NV) EEPROMused to store the wiper position for initialization during power-up. Thisenables the devices to be used in “dumb” applications where there isno host processor. The 3-wire SPI-compatible serial interface allowscommunication at data rates up to 5MHz. The devices provide threenominal resistance values: 50kΩ (MAX5422), 100kΩ (MAX5423), or200kΩ (MAX5424). The nominal resistor temperature coefficient is35ppm/°C end-to-end and only 5ppm/°C ratiometric.HV DDGND8-BITSHIFTREGISTER8 256-8-BIT8 256POSITIONLATCHDECODERWLCSSCLKDINSPIINTERFACEPOR8-BITNVMEMORYMAX5422MAX5423MAX5424Block diagram of the MAX5422/MAX5423/MAX5424.20 Maxim Smart Grid Solutions