Hi,

I create a device powered by a LiPo battery. It'll have an OLED SSD1306 128x32px I2C display and a TINY414 microcontroller. And I wonder how this display could be powered because I found a lot of different circuits on the Internet and I don't know which one is correct. According to the documentation:

- Pin VDD (Power supply pin for core logic operation) should have a voltage of 1.65V to 3.3V. ->> So I decided to use a 3V LDO stabilizer, which will lower the battery voltage (I assume the range of volatility: 3.2V-4.2V), which varies in a fairly wide range.

- The VBAT pin (Power Suppply for DD / DC converter) can have a voltage in the range of 3.5-4.2V. ->> So I decided to power this voltage conventer directly from the battery. I know the battery voltage can go below 3.5V, but I checked it and the voltage conventer works fine for 2.8V, so it shouldn't be a problem here. (The internal converter generates a voltage of VCC = 7V to 15V).

I designed a diagram like this bellow.



As you can see I added a Q1 transistor to connect the internal DC / DC converter to +3.6V (battery +). According to the documentation, the power should be connected first to Vdd, then to Vbat / Vcc (power to the OLED panel).
The OLED_VBAT_IN pin is connected to the TINY414 port powered directly from the battery (+ 3V6)




Now I wonder if this approach is right and is the circuit diagram correct?

 

R14 allow battery voltage to enter the MCU. This is not what you want. R14 should be much larger since MOSFET needs very little current to work, say +100kohm.
To isolate bat voltage from MCU:

 

But what if I power the MCU directly from the battery, before the LDO? The range of supply voltages of the TINY414 is within the range of battery voltage changes

 

But what if I power the MCU directly from the battery, before the LDO? The range of supply voltages of the TINY414 is within the range of battery voltage changes

and how do you control the LCD driver chip when it works with 3V and MCU with 3,6V ?

 

and how do you control the LCD driver chip when it works with 3V and MCU with 3,6V ?

Communication is via I2C and the pull up resistors are connected to 3V

 

You have MCU pins connected to LCD IC with voltage difference of 3.6 <--> 3.0. Bat pin can be even 4.2V if fully charged.
I see no reason why you should reject my post #2 circuit and trying to get problems with interconnecting two different voltages between 2 IC chips.

 

Why are you using the tiny414. The old tiny micros are pretty good and only need a single supply voltage. You also need to be careful using any quality acting and the oled displays. The sad 1306 has no onboard ram, so all images are stored in the micro. Wu Ty h only 4k it's easy to run out of space. When using the oled displays, I do the software development on an arduino uno and then check the program size to see whether it will fit into an attiny.

 

Not trying to be funny, but what is "quality acting"?
Robert de Niro?
There's a very good blog on using AtTiny's and OLED displays under the name Technoblogy

 

The perils of autocorrect. Justified to show AI is not as smart as a human. Substitute quality acting with attiny.

 

The perils of autocorrect. Justified to show AI is not as smart as a human. Substitute quality acting with attiny.

I like it.
Not in a million years would I have suspected "acting" = attiny.
One to add to dictionary..
Still puzzled by Wu Ty h
A new library?

 

Chinglish
it means - the tiny414 has only.

 

I was able to start the display on this ATTINY414. My design is very simple, it is about simply displaying the temperature. I am handling the display without any buffer in the microcontroller RAM.

So what do you think about this transistor for later connecting the VBAT pin to the power supply? Is it necessary?