DS1858

The DS1858 dual temperature-controlled nonvolatile (NV) variable resistors with three monitors consists of two 50k 256-position linear variable resistors, three analog monitor inputs (MON1, MON2, MON3), and a direct-to-digital temperature sensor. The device provides an ideal method for setting and temperature-compensating bias voltages and currents in control applications using minimal circuitry. The variable resistor settings are stored in EEPROM memory and can be accessed over the 2-wire serial bus.

The user can read the registers DS1858 that monitor the VCC, MON1, MON2, MON3, and temperature analog signals. After each signal conversion, a corresponding bit is set that can be monitored to verify that a conversion has occurred. The signals also have alarm flags that notify the user when the signals go above or below the userdefined value. Interrupts can also be set for each signal.

The position values of each resistor DS1858 can be independently programmed. The user can assign a unique value to each resistor for every 2 increment over the -40 to +102 range.

Two buffers DS1858 are provided to convert logic-level inputs into open-drain outputs. Typically these buffers are used to implement transmit (Tx) fault and loss-of-signal (LOS) functionality. Additionally, OUT1 can be asserted in the event that one or more of the monitored values go beyond user-defined limits.