NI PXI-6551 50 MHz Digital Waveform Generator

The NI PXI-6551 is a 50 MHz digital waveform generator and analyzer built for high-speed digital signal generation and capture. It delivers 20 bidirectional channels with per-cycle, per-channel direction control, programmable voltage levels from -2.0 V to 5.5 V in 10 mV steps, and configurable onboard memory up to 64 Mb per channel. Channel-to-channel skew is ±300 ps typical with ±900 ps maximum, and maximum data toggle rate reaches 25 MHz. The instrument supports NRZ data formats with three data position modes referenced to the sample clock, and includes four additional programmable function interface (PFI) channels. Output impedance is 50 Ω nominal with ±50 mA per-channel drive strength and ±600 mA maximum across all data, clock, and PFI channels. A 68-pin VHDCI connector provides digital data and control connectivity. The PXI-6551 phase-locks to the 10 MHz PXI backplane reference or external precision clock, and exports synchronized clocking via dedicated output terminals. Sample clock frequency ranges from 48 Hz to 50 MHz, with external clock input spanning 20 kHz to 50 MHz. Power consumption is 26.5 W maximum. The module integrates into PXI systems using the Synchronization and Memory Core (SMC) architecture for mixed-signal test and prototyping applications requiring precise timing and custom protocol verification.

– Technical Specifications

• Maximum Sample Clock Rate: 50 MHz
• Channels: 20 bidirectional with per-cycle, per-channel direction control
• Onboard Memory: 1 Mb/channel, 8 Mb/channel, or 64 Mb/channel options
• Data Format: NRZ
• Data Position Modes: Sample Clock Rising Edge, Sample Clock Falling Edge, Delay from Sample Clock Rising
• Programmable Voltage Levels: -2.0 V to 5.5 V (10 mV resolution)
• Generation Voltage Range: -0.5 V to 5.5 V at up to 50 MHz; -2.0 V to 3.7 V at up to 50 MHz
• Generation Voltage Swing: 400 mV to 6 V
• DC Voltage Accuracy: ±20 mV (into 1 MΩ)
• Output Impedance: 50 Ω nominal at 25 °C (0.2 Ω/°C temperature coefficient)
• Maximum Drive Strength: ±50 mA per channel; ±600 mA total across all data, clock, and PFI channels
• Input Protection: -2.3 V to 6.8 V
• Channel-to-Channel Skew: ±300 ps typical, ±900 ps maximum
• Maximum Data Toggle Rate: 25 MHz
• Sample Clock Frequency Range: 48 Hz to 50 MHz
• Clock In Frequency Range: 20 kHz to 50 MHz
• PXI_STAR Frequency Range: 48 Hz to 50 MHz
• Programmable Function Interface: 4 channels with per-channel direction control
• Clock Terminals: 3 input, 2 output
• Error FIFO Depth: 4,094
• Power Consumption: 26.5 W maximum

– Key Features

• Per-cycle, per-channel direction control for flexible signal routing
• Deep onboard memory with three capacity options for extended pattern storage
• Digital Waveform Editor included with 8 Mb and 64 Mb models
• Phase-locking to 10 MHz PXI backplane reference or external precision clock
• Tight channel-to-channel synchronization via SMC architecture
• 68-pin VHDCI connector for high-density digital connectivity

– Typical Applications

• Memory chip functional testing
• Digital communication protocol validation
• Custom digital protocol verification
• Mixed-signal test system integration

– Compatibility & Integration

The PXI-6551 operates within the PXI form factor and synchronizes with other modules through the Synchronization and Memory Core (SMC) architecture, enabling tightly coordinated multi-instrument test and measurement systems.