MT90401AB1

Telecom Overview

The MT90401AB1 is a SONET/SDH System Synchronizer manufactured by Microchip Technology, originally designed by Zarlink Semiconductor. It is housed in an 80-pin LQFP package (14x14 mm) and operates within a temperature range of -40°C to +85°C. The device functions as a digital phase-locked loop (DPLL) requiring a 3.3V supply voltage. It accepts selectable input reference frequencies of 8 kHz, 1.544 MHz, 2.048 MHz, or 19.44 MHz from two independent sources. Key performance specifications include a holdover accuracy of 0.02 ppm and compliance with GR-253-CORE Stratum 3, GR-1244-CORE Stratum 3, and ITU-T G.813 standards.

Telecom Feature Summary

• Provides comprehensive clock outputs including OC-3/STM-1, DS3, E3, 19.44 MHz, DS2, E1, T1, 8 kHz, and ST-BUS signals.
• Features a Time Interval Error (TIE) corrector circuit that prevents phase steps during reference switching between primary and secondary inputs.
• Supports both hardware control via external pins and microprocessor control through an 8-bit parallel interface.
• Includes JTAG boundary scan capability for testing and verification.

Telecom Applications

• SONET/SDH Add/Drop multiplexers
• SONET/SDH uplinks
• Integrated access devices
• ATM edge switches

Telecom Procurement Notes

Verify the component authenticity by checking the manufacturer markings against the official datasheet specifications. Confirm the package type matches the 80-pin LQFP form factor and ensure the operating temperature range meets the required environmental conditions. Validate that the specific suffix indicates lead-free matte tin plating if RoHS compliance is necessary for the assembly process.

Telecom Selection Notes

Select this component when designing synchronization circuits for SONET and SDH networks requiring Stratum 3 timing accuracy. Ensure the design accommodates the 3.3V power supply and provides the necessary 20 MHz master clock input. Consider the interface requirements, as the device supports both direct hardware pin control and complex microprocessor management modes depending on system architecture needs.

Telecom Part Context

This part belongs to the MT90401 family of SONET/SDH synchronizers. The AB1 suffix specifically denotes a lead-free version with matte tin plating, packaged in trays. It is functionally equivalent to the standard MT90401AB but adheres to stricter environmental regulations regarding hazardous substances in electronic components.

Telecom Replacement Considerations

Direct replacements must match the 80-pin LQFP package and support SONET/SDH synchronization at Stratum 3 levels. Verify compatibility with existing 3.3V logic levels and interface protocols. Consult Microchip or authorized distributors for current availability of lead-free variants if transitioning from older non-compliant stock.

Telecom FAQ

How does the MT90401 handle phase changes during reference switching?

The device utilizes a Time Interval Error (TIE) corrector circuit. During a switch between primary and secondary references, it temporarily enters holdover mode to measure the phase difference and adjusts a programmable delay line, ensuring no phase step occurs at the DPLL input or output.

What are the supported input reference frequencies?

The MT90401 accepts four selectable input reference frequencies: 8 kHz, 1.544 MHz, 2.048 MHz, and 19.44 MHz. Both primary and secondary inputs must operate at the same selected frequency.

Can the device be controlled without a microprocessor?

Yes, the MT90401 supports a Hardware Mode where operation is controlled directly via external control pins such as MS1, MS2, FS1, FS2, and RSEL, eliminating the need for a microprocessor interface.