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NTE8374 Integrated Circuit Seven-Segment Latch/Decoder/Driver for Common Anode LED's
Description: The NTE 8374 is a 7-segment decoder driver in a 16-Lead DIP type package incorporating input latches and output circuits to directly drive common anode LED displays. Features: D High speed input latches for data storage D 15mA constant current sink capability to directly drive common anode led displays D Increases incandescent display life D Active low latch enable for easy interface with MSI circuits D Data input loading essentially zero when latch disabled D Automatic ripple blanking for suppression of leading and/or trailing-edge zeroes. Input Loading/Fan-Out: Description Address (Data) Inputs, Latch Enable Input (Active LOW) Ripple Blanking Input (Active LOW) Ripple Blanking as Output (Active LOW) Ripple Blanking as Input (Active LOW) Constant Current Outputs (Active LOW) Pin Name A0 - A3 LE RBI RBO RBO a-g High 1.0 0.5 0.5 1.0 - Open Collector Low 0.25 (Note 1) 0.25 0.25 0.5 0.75 15mA
Note 1. Except Loading is 10A @ 0.4V when LE is HIGH. Absolute Maximum Ratings: Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +5.5V Input Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -30mA to +5.0mA Voltage Applied to Outputs in HIGH State: Standard TTL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to VCC value Open Collector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +7.0V VCC Pin Potential to GND Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +7.0V Current Applied to Output in LOW State (Max) . . . . . . . . . . . . . . . . . . . . . . . . . . . . twice the rated IOL Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65 to +150C Ambient Temperature Range Under Bias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to +125C Junction Temperature Range Under Bias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to +175C Recommended Operating Conditions: Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +4.75V to +5.25V Free Air Ambient Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0C to +70C
Functional Description: The NTE8374 is a 7-segment decoder/driver with latches on the address inputs and active LOW constant current outputs to drive LEDs directly. This device accepts a 4-bit binary code and produces output drive to the appropriate segments of the 7-segment display. It has a decode format which produces numeric codes "0" through "9" and other codes. Latches on the four data inputs are controlled by an active LOW Latch Enable, LE. When LE is LOW, the state of the outputs is determined by the input data. When LE goes HIGH, the last data present at the inputs is stored in the latches and the outputs remain stable. The LE pulse width necessary to accept and store data can be routed directly from high speed counters and frequency dividers into the display without slowing down the system clock or providing intermediate data storage. The latch/decoder combination is a simple system which drives LED displays with multiplexed data input from MOS time clocks, DVMs, calculator chips, etc. Data inputs are multiplexed while the displays are in static mode. This lowers component and insertion costs, since several circuits-seven resistors per display, strobe drivers, a separate display voltage source, and clock failure detect circuits-traditionally found in multiplexed display systems are eliminated. It also allos low strobing rates to be used without display flicker. Another NTE8374 feature is the reduced loading on the data inputs when the Latch Enable is HIGH (only 10A typ). This allows many NTE8374s to be driven from a MOS device in multiplex mode without the need for drivers on the data lines. The NTE8374 also provides automatic blanking capability 0060.0300 would be displayed as 60.03. Leading-edge zero suppression is obtained by connecting the Ripple Blanking Output (RBO) of a decoder to the Ripple Blanking Input (RBI) of the next lower stage device. The most significant decoder stage should have the RBI input grounded; and since suppression of the least significant integer zero in a number is not usually desired, the RBI input of this decoder stage should be left open. A similar procedure for the fractional part of a display will provide automatic suppression of trailing-edge zeros. The RBO terminal of the decoder can be or tied with a modulating signal via an isolating buffer to achieve duration intensity modulation. A suitable signal can be generated for this purpose by forming a variable frequency multivibrator with a cross coupled pair of TTL or DTL gates. DC Characteristics: (TA = 0 to +70C unless otherwise specified)
Parameter Output Voltage, Applied (OFF) Output LOW Current, a - g Output HIGH Current, a - g Power Supply Current Symbol VOUT IOL IOH ICC Test Conditions Separate LED Supply VCC = 5V, VOL = 3V, TA = +25C VCC = Max, VOUT = 5.5V VCC = Max, VIN = GND, VOUT = 3V Min - 12 - - Typ - - - - Max 10 18 250 50 Unit V mA A mA
AC Characteristics: (VCC = +5VTA = +25C unless otherwise specified)
Parameter Propagation Delay, An to a - g Propagation Delay, LE to a - g Symbol Test Conditions Min - - Typ - - Max 140 140 Unit ns ns tPLH, tPHL CL = 15pF, RL = 1k tPLH, tPHL CL = 15pF, RL = 1k
AC Operating Requirements: (VCC = +5VTA = +25C unless otherwise specified)
Parameter Setup Time HIGH or LOW, An to LE Hold Time HIGH or LOW, An to LE LE Pulse Width LOW Symbol ts (H) ts (L) th (H) th (L) tw (L) Test Conditions Min 75 30 0 0 85 Typ - - - - - Max - - - - - Unit ns ns ns ns ns
Truth Table:
Binary State - 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 X Inputs LE H L L L L L L L L L L L L L L L L L X RBI
Note2
Outputs A1 X L L L H H L L H H L L H H L L H H X A0 X L L H L H L H L H L H L H L H L H X a H L H L L H L L L L L H L H H L H H b H L L H L L L L L L L H H L H H H H c H L L H L L L L L L L H H L H H H H d H L H L L H L L H L L H L H L H H H e H L H L H H H L H L H H L L L L H H f H L H H H L L L H L L H L L L L H H g H H H L L L L L H L L L L L H L H H RBO H L H H H H H H H H H H H H H H H H L Note 3 ------------ STABLE ----------- Diaplay STABLE BLANK 0 1 2 3 4 5 6 7 8 9 - E H L P BLANK BLANK
A3 X L L L L L L L L L H H H H H H H H X
A2 X L L L L L H H H H L L L L H H H H X
L H X X X X X X X X X X X X X X X X
H = HIGH Voltage Level, L = LOW Voltage Level, X = Immaterial Note 2. The RBI will blank the display only if a binary zero is stored in the latches. Note 3. RBO used as an input overrides all other input conditions.
Pin Connection Diagram
A1 1 A2 2 LE 3 RBO RBI 4 5
16 VCC 15 f 14 g 13 a 12 b 11 c 10 d 9e
A3 6 A0 7 GND 8
16
9
1
8
.870 (22.0) Max
.260 (6.6) Max .200 (5.08) Max
.100 (2.54) .700 (17.78)
.099 (2.5) Min

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