The TCM1030 and TCM1050 dual transient-voltage suppressors are designed specifically for telephone line
card protection against lightning and transients (voltage transients) induced by ac lines.
One of the TIP terminals (pin 1 or 8) and one of the RING terminals (pin 4 or 5) are connected to the tip and ring circuits of a SLIC
(subscriber-line interface circuit). The battery feed connections between the SLIC and the subscriber line are
from the remaining TIP (pin1 or 8) and RING (pin 4 or 5) through the TCM1030 or the TCM1050 to the tip and
ring lines. Transients are suppressed between tip and ground, and ring and ground.
Positive transients are clamped by diodes D1 and D2. Negative transients that are more negative than VS cause
the SCRs, Q1 and Q2, to crowbar. The high holding current of the SCRs prevent dc latchup as the transient
The TCM1030 and TCM1050 are characterized for operation from -40°C to 85°C.
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