I understand the basics of LED matrices & multiplexing. I understand that LEDs are current-driven, i.e., they won't light below a certain current. I know that one uses Ohm's law to calculate the value of the current-limiting resistor. I know that in order to light the LED, a voltage is applied to the anode thru a current-limiting resistor & the cathode is grounded.
This is what I don't understand. An individual LED requires, say, 20 mA. There is, for example, a common anode column 8X8 matrix. 8X20 = 160 mA for each column. Does the driver have to supply 160 mA to each column? But the resistance required to limit the current to 20 mA is less than the resistance required to limit the current to 160 mA. That's what confuses me. How does one supply enough current to light, in our example, a row or column 8X8 matrix, but limit the current to 20 mA for each LED? 8X8 = 64. 64X20mA = 1.28 A. Does the driver have to supply 1.28 A to each row or column?
This is what I don't understand. An individual LED requires, say, 20 mA. There is, for example, a common anode column 8X8 matrix. 8X20 = 160 mA for each column. Does the driver have to supply 160 mA to each column? But the resistance required to limit the current to 20 mA is less than the resistance required to limit the current to 160 mA. That's what confuses me. How does one supply enough current to light, in our example, a row or column 8X8 matrix, but limit the current to 20 mA for each LED? 8X8 = 64. 64X20mA = 1.28 A. Does the driver have to supply 1.28 A to each row or column?
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