The SY84113BU low power limiting post amplifier is designed for use in fiber-optic optical modules for multirate applications up to 1.25Gbps. The device connects to a typical transimpedance amplifier (TIA) and can produce output signals to CML-level waveforms. Intended for the GbE and Fibre Channel applications, the SY84113BU offers a wide loss-of-signal (LOS) range. It is able to detect input signals for as low as 5mVpp and as high as 100mVpp. The SY84113BU is intended to be used in AC-coupled input applications. The SY84113BU generates a LOS open-collector TTL output. A programmable LOS level set pin (LOSLVL) sets the sensitivity of the input amplitude detection. LOS asserts high if the input amplitude falls below the threshold set by LOSLVL and de-asserts low otherwise. The enable input (/EN) de-asserts the true output signal without removing the input signal. The LOS output can be fed back to the /EN input to implement the squelch function that maintains output stability under an LOS condition. The SY84113BU operates on a single 2.5V power supply and offers ultra-low power consumption. This device is perfectly suited to meet the stringent power requirements of the CSFP/SFP/SFF optical modules.