General Description
The MM54C915/MM74C915 is a monolithic complementary MOS(CMOS) integrated circuit, constructed with N-and P-channel enhancement-mode transistors. This circuit ac-cepts 7-segment information and converts it into BCD infor-mation. The true state of the Segment inputs can be select-ed by use of the Invert/Non-Invert control pin.A logical"0"on the Invert/Non-Invert control pin selects active high true decoding at the Segment inputs.A logical"1"on the Invert/Non-Invert control pin selects active low true decoding at the Segment inputs. In addition to 4 TTL compatible BCD outputs, an Error output and Minus output are available.
The Error output goes to an active"1"whenever a non-standard7-segment code appears at the Segment input. The BCD outputs are forced into a TRI-STATE condition when an error is detected. This allows the user to program his own error code by tying the BCD outputs to Vcc or Ground viahigh value resistors (~500k). The BCD outputs may also be forced into TRI-STATE by a logical "1"on output enable(OE).The Minus output goes to a logical"1"whenever a minus code is detected and is useful as a microprocessor inter-rupt.
The BCD outputs are in a flow-through condition when Latch Enable(LE) is at a logical"O"and latched when LE isat a logical"1". The inputs will not clamp signals to the positive supply, allowing simple level translation from MOS to TTL.
Features
aWide supply range3V-15V
■High noise immunity0.45 Vcc(typ.)■TTL compatible fan out 1 TTL load
■Selectable active true inputs
■TRI-STATE outputs wOn-chip latch
■Error output Minus output
