Is it safe to exceed IC max current rating in short bursts for LED multiplexing?

The discussion addresses the safety and feasibility of exceeding the maximum continuous current rating of integrated circuits (ICs) during short bursts for LED multiplexing in a 34x40 LED display project. The ICs in question, such as shift registers and demultiplexers, have a maximum continuous source current rating around 30mA, while the LEDs require 20mA for optimal brightness. To achieve higher brightness during brief line scans (~500µs per line, ~3% duty cycle), the user considers increasing current pulses up to approximately 600mA. Responses clarify that maximum continuous current ratings differ from peak pulse current ratings, which can be higher if duty cycle and pulse duration are within specified limits. Thermal dissipation and bond wire current capacity are critical constraints. The LED’s thermal loading and the IC’s absolute maximum ratings, including short-circuit current and pulse duration limits, must be respected to avoid device damage. Using resistors alone to limit current is unreliable due to LED forward voltage variations and temperature effects. A recommended approach is to use dedicated current regulators or buffer/drivers capable of safely sourcing the required peak current. Time-slicing or pulse-width modulation at high scanning frequencies (≥1kHz) can allow higher peak currents without exceeding average power limits, leveraging the LED’s thermal inertia and human eye persistence. Circuit topology adjustments, such as exploiting higher sinking current capabilities of logic devices or paralleling IC outputs, may also help. Overall, exceeding IC max current ratings in short bursts is possible but requires careful adherence to datasheet specifications, thermal considerations, and appropriate driver circuitry to ensure reliability and prevent damage.
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