HC4GX15 Datasheet, PDF (236/668 Pages) Altera Corporation – HardCopy IV Device Handbook

4–2
Chapter 4: Matching Stratix IV Power and Configuration Requirements with HardCopy IV Devices
HardCopy IV Power-Up Options
The four phases are listed in order:
■ Power-up phase
■ Initialization phase
■ Delay phase (replacing the configuration phase)
■ Start-up phase
Instant On (No Added Delay)
In Instant On mode, after the power supplies ramp up above the HardCopy IV
device’s power-on reset (POR) trip point, the device initiates an internal POR
sequence. After t_POR (as shown in Figure 4–1 and Figure 4–2), the power-up phase is
complete and the HardCopy IV device transitions to an initialization phase, which
releases the CONF_DONE signal to be pulled high. Pulling the CONF_DONE signal high
indicates that the HardCopy IV device is nearly ready for normal operation. For more
information, refer to Figure 4–1.
During the power-up sequence, weak internal pull-up resistors can pull the user I/O
pins high. When the power-up and initialization phases are complete, the I/O pins
are released. If the nIO_pullup pin transitions high, the weak pull-up resistors are
disabled.
f You can find the value of the internal weak pull-up resistors on the I/O pins in the
Operating Conditions table of the specific FPGA’s device handbook.
Instant On After 50 ms Delay
The Instant On After 50 ms delay mode is similar to Instant On mode. However, the
device waits an additional 50 ms during delay phase before releasing the CONF_DONE
pin. This delay is created by an on-chip oscillator. This option is beneficial if other
devices on the board (such as a microprocessor) must be initialized prior to the
normal operation of the HardCopy IV device.
A start-up phase occurs immediately after the internal registers are reset, all PLLs
used are initialized, and any I/O pins used are enabled as the device transitions into
user mode.
Figure 4–1 shows an Instant On power-up waveform in which the HardCopy IV
device is powered up and the nCONFIG, nSTATUS, and CONF_DONE pins are driven
high externally.
HardCopy IV Device Handbook, Volume 2
© June 2009 Altera Corporation