The SY88993AL limiting post amplifier, with its wide bandwidth, is ideal for use as a post amplifier in fiber-optic receivers with data rates up to 3.2Gbps. Signals as small as 4mVPP can be amplified to drive devices with CML inputs or AC-coupled PECL inputs. The SY88993AL generates a chatter-free Loss-of-Signal (LOS) open collector TTL output using an external resistor, as shown Figure 1.

The SY88993AL incorporates a programmable level detect function to identify when the input signal has been lost. This information can be fed back to the /EN input of the device to maintain stability under loss of signal conditions. Using LOS LVL pin the sensitivity of the level detect can be adjusted. The LOS LVL voltage can be set by connecting a resistor divider between VCC and VREF