SY89876LMI TR

Overview

The SY89876LMI TR is a 3.3V programmable clock divider and 1:2 fanout buffer manufactured by Microchip Technology (originally Micrel). It accepts high-speed differential inputs up to 2.5 GHz, including CML, LVPECL, LVDS, and HSTL standards, via an integrated termination network accessible through the VT pin. The device divides input frequencies by ratios of 1, 2, 4, 8, or 16 using parallel-select pins S0-S2. Outputs are LVDS-compatible with a typical swing of 350 mV. Key electrical parameters include a maximum operating frequency of 2.5 GHz, propagation delay ranging from 540 ps to 870 ps depending on input swing, and low jitter performance (<1 ps RMS cycle-to-cycle, <10 ps peak-to-peak total jitter).

Feature Summary

• Integrated programmable divider with ratios of 1, 2, 4, 8, and 16 selectable via TTL/CMOS logic pins.
• Flexible differential input buffer supporting CML, PECL, LVDS, and HSTL with unique VT pin for internal termination control.
• Low jitter design ensuring <1 ps RMS cycle-to-cycle jitter and <10 ps peak-to-peak total jitter.
• LVDS-compatible outputs with typical 350 mV swing and tight common mode voltage limits.

Applications

• SONET/SDH line cards
• Transponders
• High-end multiprocessor servers

Procurement Notes

Verify component authenticity as the datasheet originates from Micrel, Inc., which was acquired by Microchip Technology. Confirm that the specific ordering suffix 'TR' indicates tape and reel packaging. Ensure compliance with RoHS directives if lead-free variants (suffix 'G') are required for new designs, noting that the standard 'SY89876LMI' uses Sn-Pb finish.

Selection Notes

Select this component when interfacing high-speed differential clocks (CML/LVPECL) to LVDS loads requiring frequency division. The VT pin allows customization of input termination for various logic standards without external resistors. Ensure the power supply is stable at 3.3V ±10% and that the exposed pad is soldered to ground for thermal management in the MLF-16 package.

Part Context

The SY89876L belongs to Micrel's Precision Edge family of high-speed clocking devices. It serves as a bridge between high-frequency source clocks and lower-frequency LVDS destinations. The device integrates functions typically requiring separate dividers and buffers, reducing board space and signal integrity issues in complex digital systems.

Replacement Considerations

The SY89873L is a related product offering similar functionality but supports a higher maximum frequency of 2.5 GHz with different timing characteristics. Verify pin compatibility and electrical specifications before substitution.

FAQ

How is the input termination configured for different logic standards?

The device features a unique VT pin that provides access to the internal 50Ω termination network. For CML or LVDS inputs, the VT pin is left floating. For other standards like PECL or HSTL, the VT pin is connected to specific voltage levels or resistors as detailed in the application circuits.

What happens to the outputs during a reset condition?

When the /RESET pin is asserted LOW, the divider resets. In divide-by-2, 4, 8, or 16 modes, Q outputs go LOW and /Q outputs go HIGH. In pass-through mode (divide by 1), /RESET synchronously enables or disables the outputs on the next falling edge of the input clock.

Can the device handle AC-coupled inputs?

Yes, the device supports AC-coupled inputs. A VREF-AC reference voltage (approximately VCC - 1.4V) is provided on pin 10 to bias AC-coupled signals. This pin should be decoupled with a 0.01µF capacitor.