| 摘要 |
PCT No. PCT/US81/00060 Sec. 371 Date Jan. 15, 1981 Sec. 102(e) Date Jan. 15, 1981 PCT Filed Jan. 15, 1981 PCT Pub. No. WO82/02463 PCT Pub. Date Jul. 22, 1982.A circuit (10) is provided for use in a telecommunications integrated circuit which has a memory for storing a telephone number. The circuit (10) essentially comprises a latch having differential nodes (22, 28). The circuit (10) serves to detect when the supply voltage provided between the supply terminals (12, 14) drops to a level which causes loss of the data stored in the integrated circuit memory. An output signal (PUC) is driven to a low state upon detection of loss of power. For a slow return of supply power the nodes (22, 28) are respectively pulled to low and high states by current leakage through diodes (30, 36, 38) connected to the power terminals (12, 14). For a rapid supply voltage transition the latch node (28) is pulled high by capacitive coupling through a diode (30). This serves to set the latch in the condition where the output node (22) is at a low state to indicate loss of power. After generation of the PUC signal in the low state, external circuitry provides a reset signal ( phi S) which serves to reset the latch of circuit (10) to indicate that the supply voltage has been provided continuously since receipt of the last reset command by the circuit (10).
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