How to Use CD4543B-FIAX: Examples, Pinouts, and Specs

The CD4543B-FIAX is a versatile BCD-to-7-segment latch/decoder/driver integrated circuit (IC). It is designed to convert binary-coded decimal (BCD) inputs into control signals for 7-segment displays. This IC is commonly used in digital clocks, calculators, and other display devices where numerical data needs to be visually represented.

1. Power Supply: Connect pin 16 (V_DD) to the positive supply voltage (3V to 15V) and pin 8 (V_SS) to ground.
2. BCD Inputs: Connect the BCD inputs (pins 1, 2, 3, and 4) to the binary-coded decimal signals.
3. Latch Enable: Connect pin 7 (LE) to a control signal. When LE is high, the BCD input is latched.
4. Lamp Test: Connect pin 5 (LT) to ground to test all segments of the display.
5. Blanking Input: Connect pin 6 (BI/RBO) to ground to enable the display. When BI/RBO is high, all segments are turned off.
6. Segment Outputs: Connect the segment outputs (pins 9 to 15) to the corresponding segments of the 7-segment display.

• Ensure that the supply voltage does not exceed the maximum rating of 15V.
• Use current-limiting resistors for each segment output to prevent excessive current draw.
• Avoid floating inputs by connecting unused inputs to ground or V_DD.
• For reliable operation, ensure that the latch enable (LE) signal is properly controlled.

Below is an example of how to connect the CD4543B-FIAX to an Arduino UNO to drive a 7-segment display.

Arduino UNO       CD4543B-FIAX       7-Segment Display
-----------       -------------       -----------------
  5V  ----------- V<sub>DD</sub> (16) 
 GND  ----------- V<sub>SS</sub> (8) 
 D2   ----------- A (1) 
 D3   ----------- B (2) 
 D4   ----------- C (3) 
 D5   ----------- D (4) 
 GND  ----------- LT (5) 
 GND  ----------- BI/RBO (6) 
 D6   ----------- LE (7) 
                   a (9)  ----------- Segment a
                   b (10) ----------- Segment b
                   c (11) ----------- Segment c
                   d (12) ----------- Segment d
                   e (13) ----------- Segment e
                   f (14) ----------- Segment f
                   g (15) ----------- Segment g

// Define pin connections
const int pinA = 2;
const int pinB = 3;
const int pinC = 4;
const int pinD = 5;
const int pinLE = 6;

void setup() {
  // Set pin modes
  pinMode(pinA, OUTPUT);
  pinMode(pinB, OUTPUT);
  pinMode(pinC, OUTPUT);
  pinMode(pinD, OUTPUT);
  pinMode(pinLE, OUTPUT);
  
  // Initialize latch enable to LOW
  digitalWrite(pinLE, LOW);
}

void loop() {
  // Example: Display the number 5
  displayNumber(5);
  delay(1000); // Wait for 1 second
}

void displayNumber(int num) {
  // Convert number to BCD
  int bcd[4];
  for (int i = 0; i < 4; i++) {
    bcd[i] = (num >> i) & 0x01;
  }
  
  // Set BCD inputs
  digitalWrite(pinA, bcd[0]);
  digitalWrite(pinB, bcd[1]);
  digitalWrite(pinC, bcd[2]);
  digitalWrite(pinD, bcd[3]);
  
  // Latch the inputs
  digitalWrite(pinLE, HIGH);
  delay(1); // Short delay to ensure latching
  digitalWrite(pinLE, LOW);
}

1. No Display Output:

   • Solution: Check the power supply connections and ensure that the supply voltage is within the specified range. Verify that the BCD inputs are correctly connected and that the latch enable (LE) signal is properly controlled.

2. Incorrect Segments Lighting Up:

   • Solution: Verify the BCD input connections and ensure that the correct binary values are being sent to the inputs. Check for any loose or incorrect wiring.

3. All Segments Off:

   • Solution: Ensure that the blanking input (BI/RBO) is connected to ground. If BI/RBO is high, all segments will be turned off.

• Check Connections: Ensure that all connections are secure and correctly wired according to the circuit diagram.
• Verify Input Signals: Use a multimeter or oscilloscope to verify that the correct BCD input signals are being sent to the IC.
• Test with Known Good Components: If possible, test the circuit with known good components to isolate any faulty parts.

By following this documentation, users should be able to effectively utilize the CD4543B-FIAX BCD-to-7-segment latch/decoder/driver IC in their projects, ensuring accurate and reliable display of numerical data.