HC4GX15 Datasheet, PDF (478/668 Pages) Altera Corporation – HardCopy IV Device Handbook

2–20
Chapter 2: HardCopy IV GX Dynamic Reconfiguration
Quartus II MegaWizard Plug-In Manager Interfaces to Support Dynamic
Clock Requirements for the ALTGX Instance and ALTGX_RECONFIG Instance
This section describes the dynamic reconfiguration clock requirements for both the
ALTGX instance (transceiver instance) and the ALTGX_RECONFIG instance
(dynamic reconfiguration controller instance).
Clock Requirements for the ALTGX Instance
For all functional mode configurations except PCI Express (PIPE) configurations, you
must connect the reconfig_clk input port of the ALTGX instance to the same clock
that is connected to the reconfig_clk input port of the ALTGX_RECONFIG
instance.
The offset cancellation circuit requires that the minimum frequency of its input clock
is ≥ 37.5 MHz. Therefore, the ALTGX configurations, including a receiver, require that
the minimum frequency of reconfig_clk (the clock used by the offset cancellation
circuit) is 37.5 MHz.
For PCI Express (PIPE) configurations only, the fixedclk input port is used to clock
the offset cancellation circuit instead of the reconfig_clk input port. Therefore, the
reconfig_clk input port frequency range can vary from 2.5 MHz to 50 MHz in
PCI Express (PIPE) configurations.
Table 2–3 shows the range of frequency values for the reconfig_clk port.
Clock Requirements for the ALTGX_RECONFIG Instance
You must connect the reconfig_clk input port of the ALTGX_RECONFIG instance
to the same clock that is connected to the reconfig_clk input port of the ALTGX
instance.
Table 2–3 shows the range of frequency values of the reconfig_clk input port for
Receiver only, Receiver and Transmitter, and Transmitter only configuration modes
of the ALTGX instance. Table 2–3 also shows the clock requirements for the
reconfig_clk input port to the ALTGX_RECONFIG instance based on ALTGX
configurations.
1 Based on ALTGX configurations (Receiver only, Transmitter only, Receiver and
Transmitter configurations) controlled by the ALTGX_RECONFIG instance, select the
fastest reconfig_clk frequency value. This satisfies both the offset cancellation
control for receiver channels and the dynamic reconfiguration of the transmitter and
receiver channels.
Table 2–3. reconfig_clk Settings for ALTGX Instance (Note 1)
ALTGX Instance Configuration
reconfig_clk Frequency Range
Receiver and Transmitter reconfiguration configuration
37.5 MHz to 50 MHz
Receiver only reconfiguration configuration
37.5 MHz to 50 MHz
Transmitter only reconfiguration configuration
2.5 MHz to 50 MHz
Note to Table 2–3:
(1) Altera recommends the reconfig_clk signal be driven on a global clock resource.
HardCopy IV Device Handbook, Volume 3
© June 2009 Altera Corporation