The role of LED display driver IC

 

The role of LED display driver IC

 

 

 

 

 

The number of ICs corresponding to the PCB board of the module used in the LED display will be different, but the commonly used driver ICs are indispensable, such as 74HC245, 74HC04, 74HC138, 74HC595, 4953, etc., but what is the role of these different ICs in the LED module?

 

1. The role of 74HC245

 

Signal power amplification.

 

Pin 1 DIR is used for input and output port conversion, when DIR="1" is high, the signal is output from "A" and "B", and when DIR="0" is low, the signal is output from "B" and "A".

 

Pin 2-9 "A" signal input and output, A1 = B1,,,,,, A8 = B8, A1 and B1 are a group, if DIR="1"G="0", then A1 input B1 output, other similar. If DIR="0"G="0", then B1 inputs, A1 outputs, and everything else is the same.

 

Pin 10 GND, Power Ground.

 

Pins 11-18 "B" signal input and output, the function is the same as that of "A", not described.

 

Pin 19 G, enable terminal, if the pin is "1" A/B terminal signal will not be on, only when "0" A/B terminal is enabled, this pin is also to play the role of switch.

 

Pin 20 VCC, power supply positive.

 

 

 

2. The role of 74HC04

 

6-position inverter. Pin 7 GND, Power Ground. Pin 14 VCC, power supply positive. The signal is input from the A terminal and the Y terminal is inverted output, A1 and Y1 are a group, and so on. For example, if A1="1" then Y1="0", A1="0" then Y1="1", the function of other groups is the same.

 

 

3. The role of 74HC138

 

Eight-bit binary translator decimal decoder. Pin 8 GND, Power Ground. Pin 15 VCC, power supply positive pins 1-3 A, B, C, binary input pins. The 4th ~ 6th pin is controlled by the selected signal, only when the 4th and 5th pins are "0" and the 6th pin is "1", it will be gated, and the output is controlled by A, B and C signals. Any other combination will not be gated, and the output of Y0~Y7 will be "1".

 

Cascade by controlling the strobe pins to extend to sixteen bits. For example: G2A=0, G2B=0, G1=1, A=1, B=0, C=0, then Y0 is "0" and Y1-Y7 is "1".

 

 

4. The role of 74HC595

 

LED driver IC, 8-bit shift latch. Pin 8 GND, Power Ground. Pin 16 VCC, Pin 14 of the power supply positive Pin DATA, serial data input port, display data enters from here, and can only be moved in with the cooperation of clock signals. Pin 13 EN, enable port, when the pin is "1", all QA~QH ports are "1", and when "0", the output of QA-QH is controlled by the input data. The 12th pin STB, latching port, when the input data is passed into the register, only a latch signal can be supplied to send the incoming data to the QA-QH port output. Pin 11 CLK, clock port, each clock signal will move into one bit of data to the register. The 10th pin SCLR, reset port, as long as there is a reset signal, the data moved in the register will be cleared, the display screen does not use this pin, generally connected to VCC. Pin 9 DOUT, the serial data output, transfers the data to the next one. Pins 15, 1-7, parallel output port is also the drive output port, driving LED.

 

 

5. The role of 4953

 

Row drive tubes, power tubes. Inside it are two CMOS tubes, 1 and 3 pins VCC, 2 and 4 pins control pins, 2 pins control the output of 7 and 8 pins, and 4 pins control the output of 5 and 6 pins, only when 2 and 4 pins are "0", 7, 8, 5, 6 will be output, otherwise the output is a high-impedance state.

 

 

6. The role of TB62726

 

LED driver IC, 16-bit shift latch. Foot 1 GND, power ground. Pin 24 VCC, Power Positive, Pin 2 DATA, Serial Data Input Pin 3 CLK, Clock Input. Pin 4 STB, latched input. The 23rd pin output current adjustment terminal, the 22nd pin DOUT of the resistor adjustment, the 21st pin EN of the serial data output, enable the input and other functions are similar to the 74HC595, except that TB62726 is a 16-bit shift latch, and has an output current adjustment function, but there will be no high level on the parallel output port, only high impedance state and low level state. The 74HC595 parallel output port has high and low outputs. TB62726 has the same pin function as the 5026 and is structurally similar.