JAJSFM3E February 2015 – June 2018 LMH1218
PRODUCTION DATA.
The LMH1218 supports two high speed differential input ports, with internal 100-Ω terminations. The inputs must be AC coupled. The external AC coupling capacitor value should take into account the pathological low frequency content. For most applications, the RC time constant of 4.7 µF AC coupling capacitor plus the 50-Ω termination resistor is capable of handing the pathological video pattern's low frequency content.
The signal detect circuit is designed to assert when data traffic with a certain minimum amplitude is present at the input of the device. It is also designed to de-assert, or remain de-asserted, when there is noise below certain amplitude at the input to the device.
The LMH1218 has two signal detect circuits, one for each input. Each signal detect threshold can be set independently. By default, both signal detects are powered on. The user selects IN1 or IN0 through SMBus/SPI interface.