LCD Graphic Display ST7565R – voltage converter 5V – 3,3V

Recently, I started my journey with cheap LCD displays with ST7565R driver. That’s why I designed a simple circuit which purpose is to make further work with this display easier. The LCDs I’m working with are using 3.3V voltage, and in my workshop I am using microcontrollers which are working on at least 4.5V voltage. Hooking up a display to a 5V power source may damage the LCD, so I created a circuit with voltage converter from 5V to 3.3V. This way I can safely connect my display to microcontroller. Here’s the schematic for it.

schemat

Rys.1 Schematic

To convert power supply voltage from 5V to 3.3V I utilized LF33 stabilizer – low drop type which is perfect for our needs because it has a very little voltage drop which equals 0.45V. On SPI bus, there’s a 74LVC125 driver which is responsible for adjusting voltage levels. It is a chip which is supplied with quad 3-state buffers. It has an input tolerating +5V while producing 3.3V voltage. This way we can hook up most of the devices where we need to adjust voltage levels, ex. on SPI bus. The whole circuit was created using surface-mount technology. It was my first project where I used SMT, so it isn’t perfect, but it’s working. PCB and elements diagram can be found below.

PCB

Rys.2 PCB and elements diagram

Unfortunately, I had to use a few jumpers. Mount the display and jumpers on a PCB and solder them at the bottom part of the board. I strongly believe that everyone should handle the rest, the circuit isn’t very complicated and it doesn’t use many elements so there shouldn’t be any problems.

ST7565R_przod

ST7565R_tyl

List of elements needed:

– R1  2,2kΩ 1206
– R3 10kΩ 1206
– R4 150Ω 0805
– C4 1uF 0805
– C5 1uF 0805
– C6 1uF 0805
– C7 1uF 0805
– C8 1uF 0805
– C9 1uF 0805
– C10 1uF 0805
– C11 1uF 0805
– C12 1uF 0805
– C13 100nF 0805
– C14 100nF 0805
– C15 1uF 0805
– T1 ex. BC847
– U1 74LVC125D
– U2 LF33
– JP1 Gold pin header strip SMD

Here are some photos of the finished circuit!

ST7565R_all

ST7565R_zblizenie

ST7565R_zblizenie2

Here you can download a PCB design in pdf file, which are ready to be printed. To create a PCB with a toner transfer method, you must use a mirror version. Additionally, I add a library to EAGLE software with ST7565R LCD Display.

Pobierz:

File Size
PCB 30,0kb
PCB – mirror 30,1kb
PCB – assembly 481kb
Schematic 340kb
EAGLE library with LCD 1,83kb
LCD Graphic Display ST7565R – voltage converter 5V – 3,3V
Bądź pierwszy i oceń!

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