The SY88923AV limiting post amplifier with its high gain and 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 5mVp-p can be amplified to drive devices with PECL inputs. The SY88923AV generates a chatter-free Loss-of-Signal (LOS) open collector TTL output.

The SY88923AV incorporates a programmable level detect function to identify when the input signal has been lost. The LOS output will change from logic "LOW" to logic "HIGH" when input signal is smaller than the swing set by LOSLVL. This information can be fed back to the EN input of the device to maintain stability under loss-of-signal condition. Using LOSLVL pin, the sensitivity of the level detection can be adjusted. The LOSLVL voltage can be set by connecting a resistor divider between VCC and VREF shown in Figure 3. "Typical Operating Characteristics" on page 6 show the relationship between input level sensitivity and the voltage set on LOSLVL.

The LOS output is a TTL open collector output that requires a pull-up resistor for proper operation, Figure 1. (see PDF file)