TIL311_1 Datasheet, PDF (2/5 Pages) Texas Instruments – HEXADECIMAL DISPLAY WITH LOGIC

TIL311
HEXADECIMAL DISPLAY WITH LOGIC
SODS001D – MARCH 1972 – REVISED DECEMBER 1997
description
This hexadecimal display contains a four-bit latch, decoder, driver, and 4 × 7 light-emitting-diode (LED)
character with two externally driven decimal points in a 14-pin package. A description of the input functions of
this device follows.
FUNCTION
LATCH STROBE INPUT
BLANKING INPUT
LATCH DATA INPUTS (A, B, C, D)
DECIMAL POINT CATHODES
LED SUPPLY
LOGIC SUPPLY VOLTAGE (VCC)
COMMON GROUND
PIN NO.
5
8
3, 2, 13, 12
4, 10
1
14
7
DESCRIPTION
When low, the data in the latches follow the data on the latch data inputs. When high,
the data in the latches will not change. If the display is blanked and then restored
while the enable input is high, the previous character will again be displayed.
When high, the display is blanked regardless of the levels of the other inputs. When
low, a character is displayed as determined by the data in the latches. The blanking
input may be pulsed for intensity modulation.
Data on these inputs are entered into the latches when the enable input is low. The
binary weights of these inputs are A = 1, B = 2, C = 4, D = 8.
These LEDs are not connected to the logic chip. If a decimal point is used, an
external resistor or other current-limiting mechanism must be connected in series
with it.
This connection permits the user to save on regulated VCC current by using a
separate LED supply, or it may be externally connected to the logic supply (VCC).
Separate VCC connection for the logic chip
This is the negative terminal for all logic and LED currents except for the decimal
points.
The LED driver outputs are designed to maintain a relatively constant on-level current of approximately 5 mA
through each LED that forms the hexadecimal character. This current is virtually independent of the LED supply
voltage within the recommended operating conditions. Drive current varies slightly with changes in logic supply
voltage resulting in a change in luminous intensity as shown in Figure 2. This change will not be noticeable to
the eye. The decimal point anodes are connected to the LED supply; the cathodes are connected to external
pins. Since there is no current limiting built into the decimal point circuits, limiting must be provided externally
if the decimal points are used.
The resultant displays for the values of the binary data in the latches are as shown below.
0
1
2
3
4
5
6
7
8
9
10
11 12
13 14
15
2
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