SY88903

The SY88903 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 1.25Gbps. Signals as small as 5mVp-p can be amplified to drive devices with PECL inputs. The SY88903 generates a chatter-free Loss of Signal (LOS) open collector TTL output.

The SY88903 incorporates a programmble 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 LOSLVL pin the sensitivity of the level detect can be adjusted. The LOSLVL voltage can be set by connecting a resistor divider between VCC and VREF, Figure 3. Figure 4 shows the relationship between input level sensitivity and the voltage set on LOSLVL. Figure 5 shows the relationship between input level sensitivity and resistor divider ratio.The LOS output is a TTL open collector output that requires pull-up resistor for proper operation, Figure 1.