TIL309

These internally-driven seven-segment light-emitting-diode (LED) displays TIL309 contain a five-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 TIL309 contain the equivalent of 78 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.

Some of the additional features of these displays TIL309 are as follows:
• Latched BCD and decimal point logic outputs provided to drive logic processors simultaneously with the displayed data
• Minimum number of inputs required . . . 4-line BCD plus decimal point
• Overriding blanking for suppressing entire display or pulse-modulation of LED brightness
• LED test input to simultaneously turn on all display segments and decimal point
• Can be operated in a real-time mode or latched-update-only mode by use of the latch strobe input
• Displays numbers 0 through 9 as well as A, C, E, F, or minus sign
• Can be blanked by entry of BCD 13 or by use of the blanking input
• Decimal point controlled independently with decimal-point latch
• Constant-current-source TTL-LED interface for optimum performance.

The TIL309 latch outputs except QDP are active pullup, and each one, except QDP, is capable of driving three standard 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. Power dissipation is typically 575 mW with all segments on.