1.25Gbps HIGH-SPEED Micrel, Inc. SY88903 LIMITING POST AMPLIFIER SY88903 Not recommended for new designs DESCRIPTION FEATURES Up to 1.25Gbps operation The SY88903 limiting post amplifier with its high gain and wide bandwidth is ideal for use as a post amplifier in Low noise fiber-optic receivers with data rates up to 1.25Gbps. Chatter-Free LOS Generation Signals as small as 5mVp-p can be amplified to drive Open Collector TTL LOS Output devices with PECL inputs. The SY88903 generates a TTL /EN Input chatter-free Loss of Signal (LOS) open collector TTL output. Differential PECL inputs for data The SY88903 incorporates a programmble level detect Single power supply function to identify when the input signal has been lost. Designed for use with SY88902 and SY88904 This information can be fed back to the /EN input of the Available in a tiny 10-pin (3mm) MSOP 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, APPLICATIONS Figure 3. Figure 4 shows the relationship between input level sensitivity and the voltage set on LOSLVL. Figure 5 1.25Gbps Gigabit Ethernet shows the relationship between input level sensitivity and 531Mbps and 1062Mbps Fibre Channel resistor divider ratio. 622Mbps SONET The LOS output is a TTL open collector output that requires pull-up resistor for proper operation, Figure 1. Gigabit Interface Converter +5V 2k SY88903 LOS Figure 1. LOS Output with Desired Rise Time BLOCK DIAGRAM DIN DOUT Limiting ECL Amplifier Buffer DOUT DIN VREF Enable EN VCC Level Detect GND LOS LOSLVL Rev.: I Amendment: /0 M9999-061907 1 Issue Date: June 2007 hbwhelp micrel.com or (408) 955-1690Micrel, Inc. SY88903 PACKAGE/ORDERING INFORMATION Ordering Information /EN 1 10 VCC Package Operating Package Lead DIN 2 9 DOUT Part Number Type Range Marking Finish MSOP /DIN 3 8 /DOUT SY88903KC K10-1 Commercial 903 Sn-Pb K10-1 VREF 4 7 LOS SY88903KCTR(1) K10-1 Commercial 903 Sn-Pb LOSLVL 5 6 GND SY88903KH K10-1 Commercial 903 with Pb-Free Pb-Free bar-line indicator NiPdAu SY88903KHTR(1) K10-1 Commercial 903 with Pb-Free 10-Pin MSOP (K10-1) Pb-Free bar-line indicator NiPdAu Note: 1. Tape and Reel. PIN NAMES GENERAL DESCRIPTION General Pin Type Function The SY88903 is an integrated limiting amplifier intended DIN Data Input Data Input for high-frequency fiber-optic applications. The circuit /DIN Data Input Inverting Data Input connects to typical transimpedance amplifiers found within a fiber-optics link. The linear signal output from a LOS LVL Input Loss of Signal Level Set transimpedance amplifier can contain significant amounts /EN TTL Input Output Enable (active Low) of noise, and may vary in amplitude over time. The SY88903 LOS TTL Output Loss of Signal Indicator limiting amplifier quantizes the signal and outputs a voltage- (Open Collector) (active High) limited waveform. GND Ground Ground The TTL /EN pin allows the user to disable the output signal without removing the input signal. DOUT PECL Output Data Output /DOUT PECL Output Inverting Data Output VCC Power Supply Positive Power Supply VREF Output Reference Voltage Output for LOS Level Set (see Fig. 3) (1) ABSOLUTE MAXIMUM RATINGS Symbol Rating Value Unit VCC Power Supply Voltage 0 to +7.0 V DIN, /DIN Input Voltage 0 to VCC V DOUT, /DOUT Output Voltage (with 50 load) VCC 2.5, VCC +0.3 V TA Operating Temperature Range 40 to +85 C Tstore Storage Temperature Range 55 to +125 C Note: 1. Permanent device damage may occur if absolute maximum ratings are exceeded. This is a stress rating only and functional operation is not implied at conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum ratlng conditions for extended periods may affect device reliability. M9999-061907 2 hbwhelp micrel.com or (408) 955-1690