The ACPL-M61L is an optically coupled ultra-low power 10 MBd digital CMOS optocouplers that operates with low power consumption, especially when the light emitting diode (LED) operates at low current. It is offered in a compact SO-5 package. When a low current is used to drive the LED, common mode rejection (CMR) can be affected by leakage currents. With high current drive CMR is not an issue, even though a portion of the LED current is diverted away through some leakage path—there is still sufficient LED current to bias the LED. In order to achieve the highest CMR with low current drive, split drive-current limiting resistors are recommended with a certain resistance ratio instead of a single limiting resistor.