ep3c120f780c8nes Altera Corporation, ep3c120f780c8nes Datasheet - Page 336

• Manufacturer Part Number: ep3c120f780c8nes
• Description: Cyclone Iii Device Family
• Manufacturer: Altera Corporation

Hot-Socketing Feature Implementation in Cyclone III Devices
Figure 11–1. Hot Socketing Circuit Block Diagram for Cyclone III Devices
11–4
Cyclone III Device Handbook, Volume 1
Resistor
Pull-Up
Weak
PAD
The POR circuit monitors the V
keeps I/O pins tri-stated until the device is in user mode. The weak
pull-up resistor (R) from the I/O pin to V
floating. The voltage tolerance control circuit permits the I/O pins to be
driven by 3.3 V before V
the I/O pins from driving out when the device is not in user mode. The
hot socket circuit prevents I/O pins from internally powering V
V
Figure 11–2
I/O buffers. This design ensures that the output buffers do not drive
when V
than V
socketing. There is no current path from signal I/O pins to V
V
tolerance control circuit capacitance.
R
CCINT
CCIO
during hot socketing. The V
Output
CCIO
when driven by external signals before the device is powered.
CCIO
. This also applies for sudden voltage spikes during hot
shows a transistor level cross section of the Cyclone III device
is powered before V
Input Buffer
to Logic Array
CCIO
Tolerance
Voltage
Control
and/or V
CCINT
CCINT
Output Enable
PAD
, V
leakage current charges the voltage
CCINT
or if the I/O pad voltage is higher
CCIO
CCIO
Hot Socket
Altera Corporation-Preliminary
Pre-Driver
, and V
are powered, and it prevents
Output
keeps the I/O pins from
Power On
Monitor
Reset
CCA
. voltage level and
CCINT
March 2007
CCIO
or
and