Electronic Design

Tiny T3/E3/DS3 Chips Trim Line-Card Costs

Although t1 lines dominate the networking world, the growing demand for higher data rates and greater subscriber capacity has created a run on faster T3 lines. Remember that T3 runs at a maximum rate of 44.736 Mbits/s, which is the equivalent of 28 1.544-Mbit/s T1 lines. Up until now, expense has hindered T3's proliferation. But a family of chips from Dallas Semiconductor (Maxim IC) helps lower T3/E3 line card costs and increase packaging density while improving performance.

Included in the DS315x family are the minuscule DS3/E3 and STS-1 line interface units (LIUs). They're available in single (DS3151), dual (Ds3152), triple (DS3153), and quad (DS3154) channel versions. All are packaged in a 13-mm2 CSBGA package. The quad unit is 66% smaller than competing devices.

The DS315x devices are pin-compatible, so customers can offer several different port counts for the same line-card design. Each channel is independently configurable for T3, E3, or STS-1 operation, with no changes to external components to switch among the three line rates. The DS315x devices operate from a 3.3-V supply and have 5-V-tolerant I/Os. Prices start at $22.39 for the DS3151, $43.96 for the DS3152, $63.49 for the DS3153, and $81.40 for the DS3154 (1000-up, FOB USA). Evaluation kits are available.

Dallas Semiconductor also announced its new DS3/E3 framers. The DS3146, DS3148, and DS31412 are six-, eight-, and 12-channel framers, respectively, and come in a 27-mm plastic BGA package. These framers complete a line that also includes the DS3141 (single), DS3142 (dual), DS3143 (triple), and DS3144 (quad). Dallas Semiconductor says they're the smallest framers in the industry.

The DS314x framers interface to various line interface units (LIUs), microprocessor buses, and other system components without glue logic. Each framer channel is independently configurable for DS3/E3 operation. All DS314x devices operate from a 3.3-V supply and have 5-V-tolerant I/Os. Prices start at $12.49 per port for the commercial temperature range and $14.36 per port for the industrial temperature range, both in quantities of 1000 or more.

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Dallas Semiconductor (Maxim IC)

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