John:
Per your suggestion, I have examined your data for the U band Receiver. I shall first examine the power supplies for the receiver. The data that I have elicited from your information is as follows, powers in Watts: Device Dissipation Delivered U16 0.340 0.850 U17 0.411 U18 0.384 1.200 U19 0.108 0.090 U20 0.040 0.224 ------------ ------------ Totals 1.283W 2.364W
For a grand total power dissipation of the power system of 3.647W. Of the delivered power you have identified two devices that suck up (U2 = 0.490W and U3 = 0.388W) a total of 0.878W. It is not clear where the remaining 1.486W is dissipated. Your help in identifying where this thermal energy is dumped in the module would be helpful, just to make sure that no stone remains unturned in this matter of handling these dissipations. Hot resistors could be an issue of concern......
You talk (somewhat glibly) of sinking regulator devices to PCB copper pads and such. For at least five devices, U2, U3, U16, U17, & U18 I consider that such mounting is not acceptable as such concentrated dissipations, exacerbated by the vacuum environment, must be treated more specifically in achieving heat sinking to the module housing. The module Base Plate, drawing E05 21, being of somewhat robust 1.6mm thick aluminum should help significantly in dissipating these module powers. More direct thermal coupling methods are going to be needed in this module to get that heat to the Base Plate. PCB thermal conductivities, even enhanced by added copper, are not good at all and cannot really be depended upon in these situations.
With this module "pushing" the envelop of module power rating, baring a full heatsink module, it is clear that the coatings of the module will not be bare aluminum. This raises the ante in the picture of keeping command-level modules from getting too cold in the eclipse situation. The original concept for maintaining full control of the spacecraft through a 3 hour eclipse, where the spaceframe can be as low as -130°C or lower, low power, command-sensitive modules would not become dangerously cold, provided that their dissipations are indeed low and the thermal coatings highly reflective. If on the other hand we depend upon higher dissipation modules, such as this URx, then the module temperatures may be a concern in the eclipse situation. This is all subject to detailed analytic examination upon the construction of a full spacecraft analytic model, which we do not have at the moment, we first need a detailed mechanical design before having that analytic model.
In any event, this URx presents a significant thermal challenge. Solving this challenge first needs an understanding of the physical bodies of these devices of the forenoted concern. Can you provide me with the physical information on these devices, either directly or by URL? Can you also respond to my earlier question on where the rest of the power dissipation resides? By one means or another we need to engineer a more direct thermal connection between these devices and the E05 21 Base Plate, which may require some inventiveness of our collective crania.
'73, Dick Jansson, KD1K (ex: WD4FAB) kd1k@amsat.org ---------------------------
Hi Dick, John,
Device Dissipation Delivered U16 0.340 0.850 U17 0.411 U18 0.384 1.200 U19 0.108 0.090 U20 0.040 0.224 ------------ ------------ Totals 1.283W 2.364W
For a grand total power dissipation of the power system of 3.647W.
I am particularly interested in this as the DSP device on the SDX (TMS320C6726) typically dissipates 857mW at its full 250MHz speed. It is a 144 pin LQFP PowerPad device and has a metal plate directly underneath the die that is designed to be soldered directly to the PCB ground plane.
In order to conduct heat away, TI recommend the optimum to be 100 0.33mm vias in a 10x10 matrix.
See http://www.g6lvb.com/dspthermal.jpg for the design I developed for the prototype I use for my software development.
We will almost certainly need to conduct heat away from the device on the underside, so that would suggest to me a direct metallic interface between the board and the module housing, either milled out of the chassis itself or with an interfacing block. IT should be noted that for electrical reasons there are also 44 decupling capacitors on the bottom of the PCB that need to be considered when providing the thermal interface.
We also would need some space rated goo to ensure good thermal conductivity between the PCB and the heatsink - I am sure someone will know what this is!
One final thing - 3.647W seems very high for the receiver function. Is this based on real figures or device spec sheets, and if the latter are these worst case or typical values?
73, Howard G6LVB
PowerPADT Thermally Enhanced Package http://focus.ti.com/lit/an/slma002a/slma002a.pdf
PowerPADT Layout Guidelines http://focus.ti.com/lit/an/sloa120/sloa120.pdf
PowerPADT Made Easy http://www-s.ti.com/sc/psheets/slma004b/slma004b.pdf
Howard:
Some time ago, Bob McGwier and I discussed the SDX thermal issue and pretty well decided that this module would need to be one of our heat sink module designs, either E05 25 or if you need it larger the E05 15 module. These will be specially treated in their mounting in the spacecraft and not be thermally isolated from the spaceframe as the other, non-power modules are handled. In this module the power devices are clamped directly to the heat sink using a space-rated thermal compound at their interfaces. The interfacing of devices such as the PowerPAD from TI, will need some study of the papers that you have referenced. That will not obviate the treatment of the module as a power device, however. I shall be back to you on this. In the meantime, please take the time to study the drawings on these modules so that you become familiar with this design.
Dick Jansson, KD1K (ex: WD4FAB) kd1k@amsat.org ---------------------------
-----Original Message----- From: Howard Long [mailto:eagle@howardlong.com] Sent: Tuesday, 20 February, 2007 1117 To: 'Dick Jansson-rr'; 'AMSAT Eagle ' Subject: RE: [eagle] URx
Hi Dick, John,
Device Dissipation Delivered U16 0.340 0.850 U17 0.411 U18 0.384 1.200 U19 0.108 0.090 U20 0.040 0.224 ------------ ------------ Totals 1.283W 2.364W
For a grand total power dissipation of the power system of 3.647W.
I am particularly interested in this as the DSP device on the SDX (TMS320C6726) typically dissipates 857mW at its full 250MHz speed. It is a 144 pin LQFP PowerPad device and has a metal plate directly underneath the die that is designed to be soldered directly to the PCB ground plane.
In order to conduct heat away, TI recommend the optimum to be 100 0.33mm vias in a 10x10 matrix.
See http://www.g6lvb.com/dspthermal.jpg for the design I developed for the prototype I use for my software development.
We will almost certainly need to conduct heat away from the device on the underside, so that would suggest to me a direct metallic interface between the board and the module housing, either milled out of the chassis itself or with an interfacing block. IT should be noted that for electrical reasons there are also 44 decupling capacitors on the bottom of the PCB that need to be considered when providing the thermal interface.
We also would need some space rated goo to ensure good thermal conductivity between the PCB and the heatsink - I am sure someone will know what this is!
One final thing - 3.647W seems very high for the receiver function. Is this based on real figures or device spec sheets, and if the latter are these worst case or typical values?
73, Howard G6LVB
PowerPADT Thermally Enhanced Package http://focus.ti.com/lit/an/slma002a/slma002a.pdf
PowerPADT Layout Guidelines http://focus.ti.com/lit/an/sloa120/sloa120.pdf
PowerPADT Made Easy http://www-s.ti.com/sc/psheets/slma004b/slma004b.pdf
I do not think this is right. I believe we discussed the ACP experiment and believe that we need heat sink module to handle the FPGA's heat engines in it.
Lyle and I have not discussed the FPGA in the SDX experiment which will be used to generator the polar representation of the baseband signal and some other processing to be passed out to the HELAPS drivers, amplifiers and modulators. I do not believe we have a heat budget yet for that part at full speed but I am expecting it to not be high.
The ACP will have two FPGA's in it probably, one for TX and one for RX. These processors will be 10w total in our best guesstimate at the current state of technology. The ACP does not have a design yet.
The TI part should not be toasty and the RAM will not be toasty. I think this note is wrong given my current understanding of the technologies involved. If I said SDX, I was not being careful.
I have been on the road and away from home for many days except for two periods under 24 hours. I have not been returning many phone calls and emails and I apologize. I will return home on Thursday at which time I am informed by my boss (N2HPE) that I need a long break. ;-) My apologies to one and all.
73's
Bob N4HY
Dick Jansson-rr wrote:
Howard:
Some time ago, Bob McGwier and I discussed the SDX thermal issue and pretty well decided that this module would need to be one of our heat sink module designs, either E05 25 or if you need it larger the E05 15 module. These will be specially treated in their mounting in the spacecraft and not be thermally isolated from the spaceframe as the other, non-power modules are handled. In this module the power devices are clamped directly to the heat sink using a space-rated thermal compound at their interfaces. The interfacing of devices such as the PowerPAD from TI, will need some study of the papers that you have referenced. That will not obviate the treatment of the module as a power device, however. I shall be back to you on this. In the meantime, please take the time to study the drawings on these modules so that you become familiar with this design.
Dick Jansson, KD1K (ex: WD4FAB) kd1k@amsat.org
-----Original Message----- From: Howard Long [mailto:eagle@howardlong.com] Sent: Tuesday, 20 February, 2007 1117 To: 'Dick Jansson-rr'; 'AMSAT Eagle ' Subject: RE: [eagle] URx
Hi Dick, John,
Device Dissipation Delivered U16 0.340 0.850 U17 0.411 U18 0.384 1.200 U19 0.108 0.090 U20 0.040 0.224 ------------ ------------ Totals 1.283W 2.364W
For a grand total power dissipation of the power system of 3.647W.
I am particularly interested in this as the DSP device on the SDX (TMS320C6726) typically dissipates 857mW at its full 250MHz speed. It is a 144 pin LQFP PowerPad device and has a metal plate directly underneath the die that is designed to be soldered directly to the PCB ground plane.
In order to conduct heat away, TI recommend the optimum to be 100 0.33mm vias in a 10x10 matrix.
See http://www.g6lvb.com/dspthermal.jpg for the design I developed for the prototype I use for my software development.
We will almost certainly need to conduct heat away from the device on the underside, so that would suggest to me a direct metallic interface between the board and the module housing, either milled out of the chassis itself or with an interfacing block. IT should be noted that for electrical reasons there are also 44 decupling capacitors on the bottom of the PCB that need to be considered when providing the thermal interface.
We also would need some space rated goo to ensure good thermal conductivity between the PCB and the heatsink - I am sure someone will know what this is!
One final thing - 3.647W seems very high for the receiver function. Is this based on real figures or device spec sheets, and if the latter are these worst case or typical values?
73, Howard G6LVB
PowerPADT Thermally Enhanced Package http://focus.ti.com/lit/an/slma002a/slma002a.pdf
PowerPADT Layout Guidelines http://focus.ti.com/lit/an/sloa120/sloa120.pdf
PowerPADT Made Easy http://www-s.ti.com/sc/psheets/slma004b/slma004b.pdf
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
Bob:
Thank you for clarifying my fuzzy brain. I mistook Howard's work for the ACP.
Dick Jansson, KD1K (ex: WD4FAB) kd1k@amsat.org ---------------------------
-----Original Message----- From: Robert McGwier [mailto:rwmcgwier@gmail.com] Sent: Tuesday, 20 February, 2007 2254 To: Dick Jansson-rr Cc: 'Howard Long'; 'AMSAT Eagle ' Subject: Re: [eagle] SDX
I do not think this is right. I believe we discussed the ACP experiment and believe that we need heat sink module to handle the FPGA's heat engines in it.
Lyle and I have not discussed the FPGA in the SDX experiment which will be used to generator the polar representation of the baseband signal and some other processing to be passed out to the HELAPS drivers, amplifiers and modulators. I do not believe we have a heat budget yet for that part at full speed but I am expecting it to not be high.
The ACP will have two FPGA's in it probably, one for TX and one for RX. These processors will be 10w total in our best guesstimate at the current state of technology. The ACP does not have a design yet.
The TI part should not be toasty and the RAM will not be toasty. I think this note is wrong given my current understanding of the technologies involved. If I said SDX, I was not being careful.
I have been on the road and away from home for many days except for two periods under 24 hours. I have not been returning many phone calls and emails and I apologize. I will return home on Thursday at which time I am informed by my boss (N2HPE) that I need a long break. ;-) My apologies to one and all.
73's
Bob N4HY
Dick Jansson-rr wrote:
Howard:
Some time ago, Bob McGwier and I discussed the SDX thermal issue and pretty well decided that this module would need to be one of our heat sink module designs, either E05 25 or if you need it larger the E05 15 module. These will be specially treated in their mounting in the spacecraft and not be thermally isolated from the spaceframe as the other, non-power modules are handled. In this module the power devices are clamped directly to the heat sink using a space-rated thermal compound at their interfaces. The interfacing of devices such as the PowerPAD from TI, will need some study of the papers that you have referenced. That will not obviate the treatment of the module as a power device, however. I shall be back to you on this. In the meantime, please take the time to study the drawings on these modules so that you become familiar with this design.
Dick Jansson, KD1K (ex: WD4FAB) kd1k@amsat.org
-----Original Message----- From: Howard Long [mailto:eagle@howardlong.com] Sent: Tuesday, 20 February, 2007 1117 To: 'Dick Jansson-rr'; 'AMSAT Eagle ' Subject: RE: [eagle] URx
Hi Dick, John,
Device Dissipation Delivered U16 0.340 0.850 U17 0.411 U18 0.384 1.200 U19 0.108 0.090 U20 0.040 0.224 ------------ ------------ Totals 1.283W 2.364W
For a grand total power dissipation of the power system of 3.647W.
I am particularly interested in this as the DSP device on the SDX (TMS320C6726) typically dissipates 857mW at its full 250MHz speed. It is a 144 pin LQFP PowerPad device and has a metal plate directly underneath the die that is designed to be soldered directly to the PCB ground plane.
In order to conduct heat away, TI recommend the optimum to be 100 0.33mm vias in a 10x10 matrix.
See http://www.g6lvb.com/dspthermal.jpg for the design I developed for the prototype I use for my software development.
We will almost certainly need to conduct heat away from the device on the underside, so that would suggest to me a direct metallic interface between the board and the module housing, either milled out of the chassis itself or with an interfacing block. IT should be noted that for electrical reasons there are also 44 decupling capacitors on the bottom of the PCB that need to be considered when providing the thermal interface.
We also would need some space rated goo to ensure good thermal conductivity between the PCB and the heatsink - I am sure someone will know what this is!
One final thing - 3.647W seems very high for the receiver function. Is this based on real figures or device spec sheets, and if the latter are these worst case or typical values?
73, Howard G6LVB
PowerPADT Thermally Enhanced Package http://focus.ti.com/lit/an/slma002a/slma002a.pdf
PowerPADT Layout Guidelines http://focus.ti.com/lit/an/sloa120/sloa120.pdf
PowerPADT Made Easy http://www-s.ti.com/sc/psheets/slma004b/slma004b.pdf
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
Bob: You note is consistent with my limited memory.
Pls call after your break and when you get a chance. 73, Jim]
Robert McGwier wrote:
I do not think this is right. I believe we discussed the ACP experiment and believe that we need heat sink module to handle the FPGA's heat engines in it.
Lyle and I have not discussed the FPGA in the SDX experiment which will be used to generator the polar representation of the baseband signal and some other processing to be passed out to the HELAPS drivers, amplifiers and modulators. I do not believe we have a heat budget yet for that part at full speed but I am expecting it to not be high.
The ACP will have two FPGA's in it probably, one for TX and one for RX. These processors will be 10w total in our best guesstimate at the current state of technology. The ACP does not have a design yet.
The TI part should not be toasty and the RAM will not be toasty. I think this note is wrong given my current understanding of the technologies involved. If I said SDX, I was not being careful.
I have been on the road and away from home for many days except for two periods under 24 hours. I have not been returning many phone calls and emails and I apologize. I will return home on Thursday at which time I am informed by my boss (N2HPE) that I need a long break. ;-) My apologies to one and all.
73's
Bob N4HY
Dick Jansson-rr wrote:
Howard:
Some time ago, Bob McGwier and I discussed the SDX thermal issue and pretty well decided that this module would need to be one of our heat sink module designs, either E05 25 or if you need it larger the E05 15 module. These will be specially treated in their mounting in the spacecraft and not be thermally isolated from the spaceframe as the other, non-power modules are handled. In this module the power devices are clamped directly to the heat sink using a space-rated thermal compound at their interfaces. The interfacing of devices such as the PowerPAD from TI, will need some study of the papers that you have referenced. That will not obviate the treatment of the module as a power device, however. I shall be back to you on this. In the meantime, please take the time to study the drawings on these modules so that you become familiar with this design.
Dick Jansson, KD1K (ex: WD4FAB) kd1k@amsat.org
-----Original Message----- From: Howard Long [mailto:eagle@howardlong.com] Sent: Tuesday, 20 February, 2007 1117 To: 'Dick Jansson-rr'; 'AMSAT Eagle ' Subject: RE: [eagle] URx
Hi Dick, John,
Device Dissipation Delivered U16 0.340 0.850 U17 0.411 U18 0.384 1.200 U19 0.108 0.090 U20 0.040 0.224 ------------ ------------ Totals 1.283W 2.364W
For a grand total power dissipation of the power system of 3.647W.
I am particularly interested in this as the DSP device on the SDX (TMS320C6726) typically dissipates 857mW at its full 250MHz speed. It is a 144 pin LQFP PowerPad device and has a metal plate directly underneath the die that is designed to be soldered directly to the PCB ground plane.
In order to conduct heat away, TI recommend the optimum to be 100 0.33mm vias in a 10x10 matrix.
See http://www.g6lvb.com/dspthermal.jpg for the design I developed for the prototype I use for my software development.
We will almost certainly need to conduct heat away from the device on the underside, so that would suggest to me a direct metallic interface between the board and the module housing, either milled out of the chassis itself or with an interfacing block. IT should be noted that for electrical reasons there are also 44 decupling capacitors on the bottom of the PCB that need to be considered when providing the thermal interface.
We also would need some space rated goo to ensure good thermal conductivity between the PCB and the heatsink - I am sure someone will know what this is!
One final thing - 3.647W seems very high for the receiver function. Is this based on real figures or device spec sheets, and if the latter are these worst case or typical values?
73, Howard G6LVB
PowerPADT Thermally Enhanced Package http://focus.ti.com/lit/an/slma002a/slma002a.pdf
PowerPADT Layout Guidelines http://focus.ti.com/lit/an/sloa120/sloa120.pdf
PowerPADT Made Easy http://www-s.ti.com/sc/psheets/slma004b/slma004b.pdf
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
participants (4)
-
Dick Jansson-rr -
Howard Long -
Jim Sanford -
Robert McGwier