NB2309AC1HDT

Overview

The NB2309AC1HDT is a commercial-grade, 3.3 V zero delay clock buffer manufactured by onsemi in a 16-pin TSSOP package. It accepts one reference input and drives nine low-skew outputs (configured as two banks of four plus one feedback output). The device incorporates an on-chip PLL that locks to the REF pin, ensuring zero input-to-output propagation delay when outputs are uniformly loaded. Operating at frequencies up to 133 MHz, it features higher drive capability than standard -1 variants, with output rise/fall times under 1.5 ns. Key performance metrics include less than 250 ps output-to-output skew and cycle-to-cycle jitter below 200 ps.

Feature Summary

• Zero Delay Buffer: On-chip PLL ensures zero input-to-output propagation delay.
• High Drive Capability: -1H variant offers faster rise/fall times (<1.5 ns) compared to standard versions.
• Low Skew Performance: Guaranteed output-to-output skew <250 ps and device-to-device skew <700 ps.
• Flexible Configuration: Two selectable output banks (4+4) allow independent control or three-stating via S1/S2 inputs.

Applications

• Distribution of high-speed clocks in Pentium/C0082 based systems.
• CPU and PCI bus frequency synchronization.
• Multi-device clock distribution networks requiring low skew.

Procurement Notes

Verify the specific suffix 'DT' confirms the TSSOP-16 package and 'C1' indicates the commercial temperature range (0°C to 70°C). Confirm RoHS compliance status if required, as non-G suffixes may not be lead-free. Check current availability as this component series may have limited stock or end-of-life status depending on the distributor.

Selection Notes

Select the NB2309AC1HDT over the standard NB2309AC1D when higher drive strength and faster transition times are required for signal integrity at 133 MHz. Ensure the application requires exactly nine buffered outputs. For industrial temperature ranges (-40°C to 85°C), select the AI1H variant instead. Verify load capacitance requirements (10 pF for >100 MHz) to maintain specified jitter and skew parameters.

Part Context

This part belongs to the NB2309A family of 3.3 V zero delay buffers. The 'H' designation specifically denotes the high-drive version with improved switching characteristics compared to the base '1' devices. It is functionally compatible with other members of the NB230x series but offers enhanced performance for demanding high-frequency applications.

Replacement Considerations

Direct pin-compatible substitutes within the same family include NB2309AI1HDT (Industrial Temp) or NB2309AC1DT (Standard Drive). Cross-manufacturer equivalents like Microchip PL123-09SC may require schematic review due to potential differences in drive strength or PLL architecture.

FAQ

How is zero input-to-output delay achieved?

Zero delay is achieved by using the CLKOUT pin as the internal feedback source for the on-chip PLL. To maintain this characteristic, all outputs, including CLKOUT, must be loaded with equal capacitance.

What is the difference between the -1 and -1H versions?

The -1H version provides higher drive strength, resulting in significantly faster rise and fall times (typically <1.5 ns vs. ~2.5 ns for -1) while maintaining the same operating frequency and functional specifications.

Can unused outputs be disabled?

Yes, Bank B outputs can be three-stated independently using the Select inputs (S1, S2). This allows flexibility in distributing only the required number of clock signals.