Re: [GUIDE] 3.5 inch HDMI Display - high energy usage
Posted: Fri Jun 01, 2018 3:13 am
I am using the Kedei HDMI display and have been experimenting with its power supply. It has the DS1117 as well, but three times: one for 1.8V and two for 3.3V. The 1.8V is for the central display controller RTD2660. One of the 3.3V is for the LCD and it's backlight. The other one seems to supply the T25S40 EEPROM including the firmware and the TSC2046 touch controller. The CS4334 D/A converter is powered by 5V. Without 5V supply there is no sound.
I measured the currents and voltages at the beginning of Super Mario Land level 1 with headphones connected, so they can be compared easily.
Supplying the display with 4.962 V from a USB power supply, it draws 394 mA which is 1.955 W.
I desoldered the three DS1117 linear regulators and used 5V, 3.3V and 1.8V from the Pi, as instructed by salami738. These are my measurements:
1.80 V: 77 mA = 0.138 W
3.32 V: 234 mA = 0.777 W
4.97 V: 13 mA = 0.065 W.
In total this is a consumption of 0.98 W. That's half of the power it draws when the linear regulators are used!
Thanks to salami738 for his guide! I will be modding all my displays for future builds. This improves battery life and reduces heat inside the case.
I measured the currents and voltages at the beginning of Super Mario Land level 1 with headphones connected, so they can be compared easily.
Supplying the display with 4.962 V from a USB power supply, it draws 394 mA which is 1.955 W.
I desoldered the three DS1117 linear regulators and used 5V, 3.3V and 1.8V from the Pi, as instructed by salami738. These are my measurements:
1.80 V: 77 mA = 0.138 W
3.32 V: 234 mA = 0.777 W
4.97 V: 13 mA = 0.065 W.
In total this is a consumption of 0.98 W. That's half of the power it draws when the linear regulators are used!
Thanks to salami738 for his guide! I will be modding all my displays for future builds. This improves battery life and reduces heat inside the case.