The ACS102A is a complete controller, driver and receiver IC, supporting fullduplex asynchronous transmission from DC to 162kbps over a single serial link. Although primarily designed for single optical fibre applications, any other simple serial media may be used. The ACS102A is optimised for very low power consumption, consuming only 2 - 3mA at RS-232 data rates including power provided to the LED and 'heartbeat' monitor. In applications where the power is extracted from the RS232 data lines, this leaves a generous amount of power left for any power extraction and RS-232 level shifting circuitry. The ACS102A employs data compression and time compression techniques, affording high launch power in short bursts, leading to a low average power consumption. The advantage of this approach is that high link budgets can be achieved with inexpensive optical components. For example, the recommended set-up for RS-232 applications (19.2kbps + handshake signals) assumes that the LED is driven with a peak current of approximately 15.4mA for 6 % of the time. The machine cycle is short enough to facilitate power supply smoothing with a small external capacitor in the region of 100F.