Abstract: Maintenance of reliable and highly available electronic systems to perform servicing and preventive maintenance may need to be performed without interruption of operations. Removal of circuit cards from a chassis may render the connectors on a chassis vulnerable to inadvertent short circuiting of power sources by stray metallic objects. A configuration where the power is removed from a connector as the circuit card is being extracted eliminates his possibility. The control circuits for the power supply connections and the power supplies are themselves redundant so that they may be similarly serviced.

Abstract: Maintenance of reliable and highly available electronic systems to perform servicing and preventive maintenance may need to be performed without interruption of operations. Removal of circuit cards from a chassis may render the connectors on a chassis vulnerable to inadvertent short circuiting of power sources by stray metallic objects. A configuration where the power is removed from a connector as the circuit card is being extracted eliminates his possibility. The control circuits for the power supply connections and the power supplies are themselves redundant so that they may be similarly serviced.

Abstract: A synchronization circuit (30) includes three flip-flops responsive to a common clock signal (CLK2). The input to the first flip-flop (32) represents the least significant bit (LSB) of a counter (31) included within a first clock domain. The CLK2 signal originates from a second clock domain. The output of the first flip-flop is provided as input to the second flip-flop (34), and the second flip-flop output is provided as input to the third flip-flop (36). An exclusive-or (XOR) gate (38) generates a synchronization signal in response to outputs of the second and third flip-flops (34-36). The synchronization signal is usable within the second clock domain and activate for one period of CLK2 subsequent to every transition occurring on the LSB input. The active state of the synchronization signal indicates that a predefined set of data inputs is stable and valid. In this manner, a single unsynchronized input signal, i.e., the LSB input, can be used to synchronize the data inputs.