TIL308 Datasheet, PDF (3/7 Pages) Texas Instruments – NUMERIC DISPLAYS WITH LOGIC

TIL308, TIL309
NUMERIC DISPLAYS WITH LOGIC
SLBS002–D1096, MARCH 1972–REVISED SEPTEMBER 1992
description
These internally-driven seven-segment light-emitting-diode (LED) displays 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 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 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 latch outputs except Q_DP are active pullup, and each one, except Q_DP, 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.
Terminal Functions
PIN
NAME
NO.
DESCRIPTION
BLANKING Input (BI)
11
When low, will blank (turn off) the entire display. Mus be high for normal operation of the display.
Latch Data Inputs
A, B, C, D, DP
15, 10, 6, Data on these inputs are entered into the latches under the control of the latch strobe input. The binary
7, 12 weights of the inputs are: A = 1, B = 2, C = 4, D = 8. DP is decimal point latch data input.
Latch Outputs
QA, QB, QC, QD,
QDP
LATCH STROBE
Input (LS)
4, 1, 2, 3, The BCD data that drives the decoder is stored in the five latches and is available at these outputs. The
14
binary weights of the outputs are: QA = 1, QB = 2, QC = 4, QD = 8. QDP is decimal point latch output.
5 When low, the data in latches follow the data on the latch inputs. When high, the data in the latches are held
constant and are unaffected by new data on the latch inputs.
LED TEST Input (LT)
13 When low, will turn on the entire display, overriding the data in the latches and the blanking input. Must be
high for normal operation of the display.
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