View Full Version : LCD power requirments

03-06-2010, 09:52 PM
I just bought a 4 x 20 LCD from parallax and it calls for 5 VDC. My voltage regulater is putting out 5.20 VDC and i need to know if its going to ruin my LCD.

Mike Green
03-06-2010, 10:22 PM
If you look at most IC datasheets, you'll find that the power supply is usually given as +-10%, occasionally +-5%. With a 5V supply, that's +-0.5V. Even at 5%, that's +- 0.25V and your supply voltage is within that. Keep in mind that the output voltage of voltage regulators will vary a little with temperature and with current drain and that there will be noise superimposed on the power supply voltage. Filtering (bypass capacitors) will take care of much of the noise, but you'll need to look at the regulator datasheet to see how much the output voltage varies with temperature and current demand.

The +-10% is the normal operating voltage range. If you operate outside this range, the manufacturer doesn't guarantee that the device will operate properly. The Absolute Maximum parameters define what will cause damage to the device. Again, if you look at the datasheets, you'll see that for 5V devices, it's usually 6.5V or 7V or higher voltages that will cause damage.

03-06-2010, 10:23 PM
According to the tech-sheet "Supply Voltage +5Vdc +/-0.25V"...so 5.20V DC will be OK