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2–6 Chapter 2: USB-Blaster II Download Cable Specifications

JTAG Timing Constraints and Waveforms

USB-Blaster II Download Cable October 2014 Altera Corporation

User Guide

To use the USB-Blaster II at the maximum capability (24 MHz), meet the timing

constraints (Table 2–6) for the target device.

The timing constraints require that you consider device specifications as well as trace

propagation delays. If you do not follow the recommended constraints, you might

encounter timing issues at 24 MHz. If the target design cannot meet these constraints,

reduce the possibility of timing issues by slowing the

TCK

frequency. See “Changing

the TCK Frequency” on page 2–7 for instructions on running the USB-Blaster II at a

slower speed.

1 The simulated timing is based on a slow timing model, which is a worst-case scenario

environment.

f For device-specific JTAG timing information, refer to the related device data sheet

available from the http://www.altera.com/literature/lit-index.html web page.

Table 2–6. JTAG Timing Constraints for the Target Device

Symbol Parameter Min Max Unit

tJCP

TCK

clock period 41.67 — ns

tJCH

TCK

clock high time 20.83 — ns

tJCL

TCK

clock low time 20.83 — ns

tJPCO JTAG port clock to JTAG Header output —

5.46 (2.5 V)

2.66 (1.5 V)

tJPSU_TDI JTAG port setup time (

TDI

) — 24.42 ns

tJPSU_TMS JTAG port setup time (

TMS

) — 26.43 ns

tJPH JTAG port hold time — 17.25 ns

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Altera USB-Blaster II Manual de usuario Pagina 16