EP2C20F256C8N Datasheet, PDF (400/470 Pages) Altera Corporation – Cyclone II Device Handbook, Volume 1

PS Configuration
Figure 13–17. Multiple Device PS Configuration Using Cascaded EPC2 or EPC1 Devices
V_CC (4)
10 kΩ
VCC (1)
VCC ₍₁₎
VCC ₍₁₎
(3) 10 kΩ 10 kΩ (2) 10 kΩ (3)
VCC
Cyclone II Device 2
GND
MSEL0
MSEL1
DCLK
DATA0
nSTATUS
CONF_DONE
nCONFIG
(5) N.C. nCEO
nCE
VCC
Cyclone II Device 1
GND
MSEL0
MSEL1
DCLK
DATA0
nSTATUS
CONF_DONE
nCONFIG
nCEO
nCE
GND
EPC2 or EPC1
Device 1
DCLK
DATA
OE (3)
nCS (3) nCASC
nINIT_CONF (2)
EPC2 or EPC1
Device 2
DCLK
DATA
nCS
OE
nINIT_CONF
Notes to Figure 13–17:
(1) The pull-up resistor should be connected to the same supply voltage as the configuration device.
(2) The nINIT_CONF pin (available on enhanced configuration devices and EPC2 devices only) has an internal pull-up
resistor that is always active, meaning an external pull-up resistor should not be used on the nINIT_CONF to
nCONFIG line. The nINIT_CONF pin does not need to be connected if its functionality is not used. If nINIT_CONF
is not used or not available (e.g., on EPC1 devices), nCONFIG must be pulled to V_CC either directly or through a
resistor (if reconfiguration is required, a resistor is necessary).
(3) The enhanced configuration devices’ and EPC2 devices’ OE and nCS pins have internal programmable pull-up
resistors. If internal pull-up resistors are used, external pull-up resistors should not be used on these pins. The
internal pull-up resistors are used by default in the Quartus II software. To turn off the internal pull-up resistors,
check the Disable nCS and OE pull-ups on configuration device option when generating programming files.
(4) Use an external 10-kΩ pull-up resistor to pull the nCEO pin high to the I/O bank V_CCIO level to help the internal
weak pull-up when it feeds next device’s nCE pin.
(5) The nCEO pin can be left unconnected or used as a user I/O pin when it does not feed other device’s nCE pin.
When using enhanced configuration devices or EPC2 devices, you can
connect the Cyclone II device’s nCONFIG pin to the configuration
device’s nINIT_CONF pin, which allows the INIT_CONF JTAG
instruction to initiate FPGA configuration. You do not need to connect the
nINIT_CONF pin if it is not used. If the nINIT_CONF pin is not used or
not available (for example, on EPC1 devices), pull the nCONFIG pin to
V_CC levels either directly or through a resistor (if reconfiguration is
required, a resistor is necessary). An internal pull-up resistor on the
nINIT_CONF pin is always active in the enhanced configuration devices
and the EPC2 devices. Therefore, do not use an external pull-up resistor
if you connect the nCONFIG pin to nINIT_CONF. If you use multiple
EPC2 devices to configure a Cyclone II device(s), only connect the first
EPC2 device’s nINIT_CONF pin to the device's nCONFIG pin.
13–46
Cyclone II Device Handbook, Volume 1
Altera Corporation
February 2007