Olimex LPC2378 Board Power Consumption Problem

Development Boards MicroMod
1

Hello,

I’ve bought an Olimex LPC2378-STK development board with a nokia lcd on it. My problem is about the power consumption of the board; I realized that the bridge rectifier (DB104S) is heating very much -I’m sure that its temperature is reaching beyond 50 C.

I was wondering, if it is normal for a board like this to sink about 400mA of current from the supply when the lcd backlight and lcd itself is off and there is no program running in the flash rom?

Thanks for answers.

Regards.

2

What supply voltage? Is the board actually working OK?

Leon

3

leon_heller:
What supply voltage? Is the board actually working OK?

Leon

Yes, the board is working; I’ve even driven the lcd on it. Input supply voltage is 9 volts dc from an adaptor, the current measurement was taken from the input.

Also the board has two voltage regulators on it (5v and 3.3v).

4

Have you actually measured the input voltage? It might be a lot more than 9V if it isn’t regulated.

Leon

5

leon_heller:
Have you actually measured the input voltage? It might be a lot more than 9V if it isn’t regulated.

Leon

It’s 9.2 volts dc and has no ac component.

6

400mA seems to be a bit high.

I’ve just tested a brand new board with the LCD backlight on and displaying the Olimex logo, the current drawn at 9v is 163mA.

Try and use a different PSU.

Hope this helps.

7

Thanks for the answers.

I tried a different power supply, but the current drawn is about the same value. I managed to decrease the current drawn to about 0.33A by turning off some other peripherals.

I think I should use the board with a fan over the regulators and rectifier :slight_smile:

By the way, any suggestions will be appreciated.

8

Many possible reasons for this.

On another development board I had high dissipation because of improperly initialized pin direction registers. When 3.3v CPU pins being driven by external logic outputs were programmed as outputs, current went up! This arose from loading example code for a different development board.

Have you done the classic finger test? Just feel every component on the board (in addition to the bridge), find the hot one. On my production test rig high current usually means a chip is mounted turned 180 degrees. Is it possible to you are powering both through the dongle AND USB, shouldn’t be an issue but could be.