The SY88349NDL is a high-sensitivity, burst-mode capable limiting post amplifier designed for optical line terminal (OLT) receiver applications. The SY88349NDL satisfies the strict timing restrictions of the GPON standards by providing ultra-fast loss-of-signal (LOS) or Signal-Detect (SD) output. Auto reset and manual reset options are provided to control LOS/SD output timing. For increased flexibility, this device also includes an option to select between LOS or SD output. The device can be connected to burst-mode capable transimpedance amplifiers (TIAs) using AC or DC coupling.

The SY88349NDL generates a high-gain LOS or SD LVTTL output. A programmable LOS/SD level set pin (LOS/SDLVL) sets the sensitivity of the input amplitude detection. When LOS/SD SEL pin is left open or tied to VCC, JAM is active high, SD is selected and asserts high if the input amplitude rises above the threshold sets by LOS/SDLVL and de-asserts low otherwise. When LOS/SD SEL pin is set low or tied to GND, JAM is active low, LOS is selected and asserts low if the input amplitude rises above the threshold sets by LOS/SDLVL and de-asserts high otherwise. The LOS/SD output can be fed back to the JAM input to maintain output stability under an invalid signal conditions. Typically, 4dB  5dB SD hysteresis is provided to prevent chattering.

The SY88349NDL also features a selectable proprietary noise discriminator that aids by filtering out input signals that do not qualify as a 2.5Gbps GPON preamble signal in the initial startup phase. This feature minimizes false SD asserts that can be triggered by random noise.Read more