LED driving apparatus having feedback dimming function

An LED driving apparatus having feedback dimming function is electrically connected with several LED light strings and comprises a maximum error selector, a plurality of dimming circuits and a control module. The control module is electrically connected between each LED light string and each dimming circuit to obtain the feedback voltages of those LED light strings. The maximum error selector has the differential amplifiers having quantities conforming to those of the LED light strings and a plurality of diodes respectively cascading the output of each differential amplifier via an anode. The cathodes of those diodes also output error signal. The control module utilizes error data to generate a control command after calculation so that the action of the main power-grade circuit switch is controlled. By regulating the action of the main circuit switch, the modulation of the dimming circuit's span voltage can be achieved. Since the maximum error signal feedback is adopted, and not easily be interfered, therefor