Final project¶
TIL595 Hexadecimal display controller with shift register input¶
- Easy to cascade with the fixed number of GPIO necessary
- Better look than the 7-segments displays, with 13 segments
Description¶
The display is created with a set of 20 LEDs, some are driven alone, some a driven by two in series. The constant curent driver ensures a common brightness.
| Function | Description |
|---|---|
| Flip-flop strobe input | Shifts the data in the four registers |
| Data input | Data to be shifted in the first (MSB) register at rising level on Flip-flop strobe input |
| Reset | Resets all registers to zero |
| Load strobe input | Loads the shift register to the stage-2 register linked to the decoder |
| Segments output | Outputs to connect to anode of LEDs segments |
| Data out | Serial data output to be connected to data input of next display |
| VCC | Power input pin |
| GND | Common ground |
Schematics¶
PCB example¶
As PCBs are getting more and more precise, it probably won’t be necessary to do a dedicated packaging like what was done for the til311 chip. It allows different sizes of the display with the same chip.
Here is a PCB example the same size as a TIL311 with castelated holes, LEDs in 0201 package and a WLCSP package for the IC:
Circuit¶
The circuit with all it’s inputs and outputs on the bottom, without VCC and GND :
To be done¶
The power part of the chip has been ignored, especially the constant current part for driving the LEDs. Looking for constant-current drivers I found a chip, still being produced, that does exactly what I wanted to do : the TLC59284 from Texas Instruments. It has no decoder but since we all use microcontrollers now, it’s not that important.