Digital Dual Temperature-Controlled Resistors

N/A847 and DS1848 dual temperature-controlled NV variable resistors incorporate temperature compensation circuitry with dual variable resistors and EEPROM. The manufacturer states that this combination enables a new level of precision in controlling laser intensity in optical transceivers. As signal speeds increase in communications equipment, the resistors can provide safe, reliable laser operation.

Dual 256-position, linear taper resistors are used in optical transceiver modules to control current to VCSELs (vertical cavity surface emitting lasers) or laser diodes. During operation, an integrated digital thermometer continuously measures temperatures, which are compared to resistance characteristics stored in on-chip EEPROM. As temperatures vary, the new resistors are designed to automatically compensate by adjusting resistance. Thermal readings are also available as direct outputs communicated over an industry-standard, 2-wire interface.

The resistors are considered well suited for next-generation Ethernet, SONET, SDH, or fiber channel designs. The DS1848 differs from the DS1847 in offering an additional 128 bytes of general-purpose EEPROM. In TSSOP or die-sized flip-chip packaging, both operate with either 3V or 5V supplies and within a temperature range of -40>°C to +95°C.

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