SN75207B,pdf(Dual Sense Amplif

The SN75207B is a terminal-for-terminal replacement for the SN75107B. The improved input sensitivity makes it more suitable for MOS memory sense amplifiers and can result in faster memory cycles. Improved sensitivity also makes it more useful in line-receiver applications by allowing use of longer transmission line lengths. The SN75207B features a TTL-compatible, active-pullup output.

Input protection diodes are in series with the collectors of the differential-input transistors of the SN75207B. These diodes are useful in certain party-line systems that may have multiple V_CC+ power supplies and may be operated with some of the V_CC+ supplies turned off. In such a system, if a supply is turned off and allowed to go to ground, the equivalent input circuit connected to that supply would be as follows:

This would be a problem in specific systems that might have the transmission lines biased to some potential greater than 1.