description
These internally-driven seven-segment light-emitting-diode (LED) displays contain a BCD counter, a four-bit
latch, and a decoder/LED driver in a single 16-pin package. A description of the functions of the inputs and
outputs of these devices are in the terminal function table.
The TTL MSI circuits contain the equivalent of 86 gates on a single chip. Logic inputs and outputs are completely
TTL/DTL compatible. The buffered inputs are implemented with relatively large resistors in series with the bases
of the input transistors to lower drive-current requirements to one-half of that required for a standard Series
54/74 TTL input. The serial-carry input, actually two internal loads, is rated as one standard series 54/74 load.
The logic outputs, except RBO, are active pullup, and the latch outputs QA, QB, QC, and QD are each capable
of driving three standard Series 54/74 loads at a low logic level or six loads at a high logic level while the
maximum-count output is capable of driving five Series 54/74 loads at a low logic level or ten loads at a high
logic level. The RBO node with passive pull-up serves as a ripple-blanking output with the capability to drive
three Series 54/74 loads.
The LED driver outputs are designed specifically to maintain a relatively constant on-level current of
approximately 7 mA through each LED segment and decimal point. All inputs are diode clamped to minimize
transmission-line effects, thereby simplifying system design. Maximum clock frequency is typically 18 MHz and
power dissipation is typically 600 mW with all segments on