New resistor networks protect AMD telecom chip sets against transient power faults under bellcore ITU specs

Citation

(1999), "New resistor networks protect AMD telecom chip sets against transient power faults under bellcore ITU specs", Microelectronics International, Vol. 16 No. 1. https://doi.org/10.1108/mi.1999.21816aad.015

New resistor networks protect AMD telecom chip sets against transient power faults under bellcore ITU specs

New resistor networks protect AMD telecom chip sets against transient power faults under bellcore/ITU specs

Keywords MMC, Resistors

New thick-film line feed resistors, the B11 and B21 modules from Microelectronic Modules Corporation (MMC), provide secondary power protection on telecom circuitry switching cards that incorporate advanced micro devices (AMD) AM7920 chip sets. Compact, single in-line package (SIP) designs provide designers with drop-in solutions for meeting Bellcore and ITU telecom surge requirements. Employing MMC's patented thermal fuse, these fail-safe modules provide fault current limiting, lightning surge resistance, and power-cross dissipation.

When used with the AMD AM7920, B11 and B21 modules provide the DC feed resistor, fuse resistor, ringing source resistor, part of the ring trip bridge, ringing snubber resistor, and thermal management resistor. Resistors carry values from 50‡ to 1M‡, with typical tolerance of ±5 percent. Laser trimming provides ratio matching (longitudinal balance) to ±0.5 percent. The B11 and B21 have maximum seated heights of only 0.500" (13mm) and maximum thickness of just 0.125" (3mm).

MMC's B11 model (B11A050AA) meets Bellcore GR-1089-CORE specifications. It withstands 50 repetitions of 1,000v, 10 × 1,000 microsecond and 20 repetitions of 2,500v, 2 × 10 microsecond lightning surge pulses without degradation of present or future performance. This model also passes Bellcore's Level II lightning surge requirement of a 5,000v, 2 × 10 microsecond pulse without causing a fire or electrical safety hazard.

B21 (B21A050AA) models meet ITU-T K.20 ratings for 1kV lightning surge, 600Vrms power induction and 230Vrms power contact.

Both designs also qualify to UL 497A specifications. In addition, they meet MIL-STD-202 environmental standards for humidity (103B), solderability (208D), thermal shock (107B), resistance to solvents (215) and resistance to solder heat (210D), as well as UL 94V-0 and EC 695-2-2 flammability ratings.

For more information, contact Microelectronic Modules Corporation, 2601 S. Moorland Road, New Berlin, Wisconsin, 53151, USA. Tel: +1 (414) 785-6506; Fax +1 (414) 785-6516; E-mail sales@mmccorp.com; website at www.mmccorp.com.