NB7VPQ701M

www.onsemi.com

9

PARAMETER MEASUREMENT DIAGRAMS

Figure 9. Transmitter Differential Voltage

Figure 10. Propagation Delay

Figure 11. Output Rise and Fall Times

Rx−

Rx+

Tx−

Tx+

APPLICATION GUIDELINES

LFPS Compliance Testing

As part of USB 3.1 compliance test, the host or peripheral

must transmit a LFPS signal that adheres to the spec

parameters. When using a real−time oscilloscope to capture

this data, the scope’s trigger must be below 0 V when making

single−ended measurements. Although the differential

signal is identical to that which is expected by the USB 3.1

system, the AC common mode voltage for LFPS may fall

below 0 V during short bursts of switching signal, which is

still within the spec’s limit.

LFPS Functionality

USB 3.1 links use Low Frequency Periodic Signaling

(LFPS) to implement functions like exiting low−power

modes, performing warm resets and providing link training

between host and peripheral devices. LFPS signaling

consists of bursts of frequencies ranging between 10 to

50 MHz and can have specific burst lengths or repeat rates.

Ping.LFPS for TX Compliance

During the transmitter compliance, the system under test

must transmit certain compliance patterns as defined by the

USB−IF. In order to toggle through these patterns for various

tests, the receiver must receive a ping. LFPS signal from

either the test suite or a separate pattern generator. The

standard signal comprises of a single burst period of 100ns

at 20 MHz. In order to pass this signal through

NB7VPQ701M, the duration of the burst must be extended

to at least 200 ns.