Hi ! I have a PCI Mezzanine Card (PMC) with a Virtex 400 and a front panel connector. The Virtex is connected to the SCSI-2 style front panel connector with 68 pins.These pins are interleaved signal and ground pairs.So, I have 34 free I/O at the front panel connector. I would like to connect a little add-on board to this front panel connector. This board will be populated with a Gigabit Ethernet Controller (PMC-Sierra PM3387). Besides data and control signals I have to provide power to the add-on board. I am planning to connect the add-on board VCC plane with the I/O pins at the front panel connector. Then the Virtex will drive '1' at the front panel connector I/O. The add-on board ground plane will be connected with the ground pins at the front panel connector. Can this provide sufficient power to the add-on board ? Is there a better way to provide power ? Thanks in advance. Mark Lenz
Virtex "Virtual VCC"
Started by ●August 11, 2003
Reply by ●August 11, 20032003-08-11
Mark, your question cannot be answered without knowing the Icc consumption of that extra board. If it is <10 mA and not too picky about low Vcc, this might work if you select the strongest Output drive for the pin ( or do you intend to use multiple pins?) Once you know the current, you can experiment with a simple resistive load. :-) Peter Alfke, Xilinx ========================== lenz wrote:> > Hi ! > > I have a PCI Mezzanine Card (PMC) with a Virtex 400 and a front panel > connector. The Virtex is connected to the SCSI-2 style front panel > connector with 68 pins.These pins are interleaved signal and ground > pairs.So, I have 34 free I/O at the front panel connector. > > I would like to connect a little add-on board to this front panel > connector. This board will be populated with a Gigabit Ethernet > Controller (PMC-Sierra PM3387). Besides data and control signals I > have to provide power to the add-on board. > > I am planning to connect the add-on board VCC plane with the I/O pins > at the front panel connector. Then the Virtex will drive '1' at the > front panel connector I/O. The add-on board ground plane will be > connected with the ground pins at the front panel connector. > > Can this provide sufficient power to the add-on board ? > Is there a better way to provide power ? > > Thanks in advance. > > Mark Lenz
Reply by ●August 12, 20032003-08-12
Hi Peter, thank you for your response. The datasheet of the chip which is on the add-on board states a DC Input Current of +/- 20mA. I have a total of 4 pins to provide power to the add-on board. The Virtex datsheet states a output current for one pin of +/- 24mA for LVTTL. As a novice I would expect that one pin with +/- 24mA would be sufficient to source the add-on board which requires +/- 20mA. Is this correct ? How can I determine the value of the experiment resistor. I assume Vcc/Icc. Is this correct ? Regards, Mark Lenz Peter Alfke <peter@xilinx.com> wrote in message news:<3F37E2D9.290AF568@xilinx.com>...> Mark, your question cannot be answered without knowing the Icc > consumption of that extra board. > If it is <10 mA and not too picky about low Vcc, this might work if you > select the strongest Output drive for the pin ( or do you intend to use > multiple pins?) > > Once you know the current, you can experiment with a simple resistive > load. :-) > > Peter Alfke, Xilinx > ========================== > lenz wrote: > > > > Hi ! > > > > I have a PCI Mezzanine Card (PMC) with a Virtex 400 and a front panel > > connector. The Virtex is connected to the SCSI-2 style front panel > > connector with 68 pins.These pins are interleaved signal and ground > > pairs.So, I have 34 free I/O at the front panel connector. > > > > I would like to connect a little add-on board to this front panel > > connector. This board will be populated with a Gigabit Ethernet > > Controller (PMC-Sierra PM3387). Besides data and control signals I > > have to provide power to the add-on board. > > > > I am planning to connect the add-on board VCC plane with the I/O pins > > at the front panel connector. Then the Virtex will drive '1' at the > > front panel connector I/O. The add-on board ground plane will be > > connected with the ground pins at the front panel connector. > > > > Can this provide sufficient power to the add-on board ? > > Is there a better way to provide power ? > > > > Thanks in advance. > > > > Mark Lenz
Reply by ●August 12, 20032003-08-12
Yes, that's what I would use as resistor value.. I would use all 4 pins in parallel, and configure them such that they can only pull High ( the mirror image of opencollector ) which means: output a permanent High level and keep the outputs permanently active (Tristate control input = Low). Viel Erfolg! Peter Alfke ======================= lenz wrote:> > Hi Peter, > > thank you for your response. > > The datasheet of the chip which is on the add-on board states a DC > Input Current of +/- 20mA. I have a total of 4 pins to provide power > to the add-on board. > The Virtex datsheet states a output current for one pin of +/- 24mA > for LVTTL. As a novice I would expect that one pin with +/- 24mA would > be sufficient to source the add-on board which requires +/- 20mA. Is > this correct ? > > How can I determine the value of the experiment resistor. I assume > Vcc/Icc. Is this correct ? > > Regards, > Mark Lenz > > Peter Alfke <peter@xilinx.com> wrote in message news:<3F37E2D9.290AF568@xilinx.com>... > > Mark, your question cannot be answered without knowing the Icc > > consumption of that extra board. > > If it is <10 mA and not too picky about low Vcc, this might work if you > > select the strongest Output drive for the pin ( or do you intend to use > > multiple pins?) > > > > Once you know the current, you can experiment with a simple resistive > > load. :-) > > > > Peter Alfke, Xilinx > > ========================== > > lenz wrote: > > > > > > Hi ! > > > > > > I have a PCI Mezzanine Card (PMC) with a Virtex 400 and a front panel > > > connector. The Virtex is connected to the SCSI-2 style front panel > > > connector with 68 pins.These pins are interleaved signal and ground > > > pairs.So, I have 34 free I/O at the front panel connector. > > > > > > I would like to connect a little add-on board to this front panel > > > connector. This board will be populated with a Gigabit Ethernet > > > Controller (PMC-Sierra PM3387). Besides data and control signals I > > > have to provide power to the add-on board. > > > > > > I am planning to connect the add-on board VCC plane with the I/O pins > > > at the front panel connector. Then the Virtex will drive '1' at the > > > front panel connector I/O. The add-on board ground plane will be > > > connected with the ground pins at the front panel connector. > > > > > > Can this provide sufficient power to the add-on board ? > > > Is there a better way to provide power ? > > > > > > Thanks in advance. > > > > > > Mark Lenz