Microchip ZL40294B 20-Output PCIe Gen7 Clock Buffer
Mfr. Part #：ZL40294B
Manufacturer：Microchip Technology
Product Category：ICs / Clock Buffers
Description：3.3V DB2000QL PCIe Gen7 clock buffer with 20 LP-HCSL differential outputs, ultra-low additive jitter and SMBus control.
Package / Case：80-Lead VGQFN, 6 × 6mm
Operating Voltage：3.3V ±5%
Operating Temperature：−40°C to +105°C
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Get Price & AvailabilityMicrochip ZL40294B 20-Output PCIe Gen7 Clock Buffer
The Microchip ZL40294B is an ultra-low-jitter, 20-output PCIe clock fanout buffer designed for PCIe Gen1 through Gen7 reference clock distribution. Compliant with the Intel DB2000QL specification, the device features 20 low-power HCSL (LP-HCSL) differential outputs, a 3.3V power supply and configurable clock enable control.
The ZL40294B provides 3.5fs RMS typical PCIe Gen7 additive phase jitter under specified measurement conditions. Its integrated output termination, SMBus interface and compact 6 × 6mm package make it suitable for servers, storage systems, PCIe expansion platforms and high-speed computing equipment.
ZL40294B Key Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Microchip Technology |
| Part Number | ZL40294B |
| Device Type | DB2000QL PCIe Clock Fanout Buffer |
| PCIe Support | Gen1–Gen7 |
| Clock Outputs | 20 LP-HCSL Differential Pairs |
| Clock Frequency Range | 0–400MHz (Rev. D Datasheet) |
| Supply Voltage | 3.3V ±5% |
| Gen7 Additive Phase Jitter | 3.5fs RMS Typical |
| DB2000QL-Band Additive Jitter | 12fs RMS Typical |
| Additive Jitter at 156.25MHz | 32fs RMS Typical, 12kHz–20MHz Band |
| Output-to-Output Skew | 50ps Maximum |
| Differential Line Impedance | 85Ω with Integrated Series Termination |
| Output Enable Controls | 8 OE Pins |
| Configuration | SMBus / Side-Band Interface |
| Operating Temperature | −40°C to +105°C |
| Package | 80-Lead VGQFN, 6 × 6mm |
| Product Status | In Production |
Note: Jitter specifications depend on measurement bandwidth, clock frequency and test conditions. The latest DS20006962D datasheet should be used for detailed electrical verification.
ZL40294B Ordering Part Numbers
| Ordering Part Number | Package | Packaging |
|---|---|---|
| ZL40294BLDG6 | 80-Lead VGQFN | 490 Units / Tray |
| ZL40294BLDF6 | 80-Lead VGQFN | 4000 Units / Reel, 12mm Pitch |
| ZL40294BLDX6 | 80-Lead VGQFN | 4000 Units / Reel, 8mm Pitch |
All three ordering versions use the same lead-free 80-lead VGQFN package. The primary difference is shipment media and tape-and-reel configuration.
For production purchasing, confirm the complete ordering number, available packaging format, minimum order quantity and lead time.
PCIe Gen7 Jitter and Clock Distribution Design
The ZL40294B is designed to distribute a low-jitter reference clock to multiple PCIe devices without significantly degrading clock quality.
Its 3.5fs RMS typical PCIe Gen7 additive phase jitter makes it suitable for demanding clock distribution applications. However, engineers must distinguish buffer-added jitter from total clock-path jitter.
For PCIe Gen7 designs, check:
Reference clock quality: Evaluate the input clock phase noise and the complete jitter budget.
Clock frequency: Verify the intended reference clock frequency against the latest datasheet.
Output loading: Confirm differential transmission line impedance and receiver requirements.
Power supply noise: Follow Microchip's supply decoupling recommendations to maintain jitter performance.
Clock skew: Consider the specified 50ps maximum output-to-output skew along with PCB routing differences.
The integrated low-dropout regulator improves rejection of supply noise, while spread-spectrum transparency supports compatible PCIe reference clock architectures.
LP-HCSL Outputs and 85Ω PCB Interface
The ZL40294B provides 20 low-power push-pull HCSL differential clock outputs with integrated series termination intended for 85Ω differential transmission lines.
When routing clocks on a PCB, maintain controlled differential impedance and minimize discontinuities at the clock buffer, connector and receiving device.
Unlike a generic clock buffer, the ZL40294B is designed around the DB2000QL interface requirements. Engineers replacing an existing PCIe clock buffer should confirm the termination scheme, output voltage levels, enable functions and package pinout.
SMBus and Output Enable Control
The device provides eight output-enable pins, an SMBus interface and a side-band interface for clock management.
These control functions allow clock outputs to be managed according to system requirements. The exact output-enable behavior depends on the interface configuration and register settings.
Designers should check the PWRGD/PWRDN# control, SMBus address configuration and side-band enable settings before integrating the clock buffer into an existing platform.
Typical Applications
PCIe Gen5, Gen6 and Gen7 reference clock distribution
Enterprise servers and storage platforms
Data center networking equipment
High-speed PCIe expansion systems
Switches, routers and computing infrastructure
Datasheet and Related Clock Buffers
Official Microchip documentation:
For alternative PCIe clock distribution requirements, engineers may review the Microchip ZL40294 and ZL40295 series. These devices have different interface and specification characteristics and should not be treated as direct replacements without verifying the latest manufacturer documentation.
ZL40294B Pricing and Availability
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