WO2018056882A1

WO2018056882A1 - Soft circuit switch, method therein and system

Info

Publication number: WO2018056882A1
Application number: PCT/SE2017/050902
Authority: WO
Inventors: Niclas ARNDT
Original assignee: Embedderment AB
Current assignee: Embedderment AB
Priority date: 2016-09-26
Filing date: 2017-09-14
Publication date: 2018-03-29
Anticipated expiration: 2019-03-26
Also published as: EP3516478A1; EP3516478A4; SE540503C2; SE1630232A1

Abstract

This document presents a way to build much smaller computers with standard components without sacrificing performance. This is accomplished by a modular power delivery system, in which zero or more soft-start switching add-on boards are connected to a pre-existing stand-alone power supply, typically DC/DC-switched. The modular design creates upgrade paths that don't require replacement of existing equipment when upgrading to a more powerful graphics adapter or adding additional hard drives. Each add-on board provides at least one separated power path mainly consisting of a soft-start switch and circuitry that controls and monitors the power delivered on its path(s). Each add-on board is controlled by the pre-existing power supply or a thereto connected adapter board and comprises protection circuits such as simultaneous emergency shutdown of the entire power delivery system and prevention of system start unless all power paths are energized.

Description

SOFT CIRCUIT SWITCH, METHOD THEREIN AND SYSTEM. Terminology and Definitions

All voltages are referred to by their nominal value. For example, for this application, 12 V generally means the range of 11.4 V to 12.6 V or 10.8 V to 13.2 V.

Devices

• PSU: General term for a power delivery system.

• AC_PSU: The traditional metal box AC/DC switching power supply that is mounted inside the computer chassis. It comes in a variety of formats, conforming to one of the ATX-related standards (ATX, SFX, TFX, CFX, LFX, Flex ATX, or other). It typically supplies 3.3 V, 5 V standby, 5 V, 12 V, and -12 V. It does not have a dedicated control and monitoring connector with the required signals, so an adapter board must be used when connecting an AC_PSU to the present invention.

• DC_PSU: A general term for a DC/DC switching power supply fed by 6 V to 48 V (typically 12 V). It typically supplies 3.3 V, 5 V stand-by, 5 V, 12 V, and -12 V.

• DC_PSU_L: A legacy DC_PSU that (for obvious reasons) was not designed for interaction with the present invention. It does not have a dedicated control and monitoring connector with the required signals, so an adapter board must be used when connecting a DC_PSU_L to an AO board. It generally provides weak power delivery to the 12 V rails.

• DC_PSU_M: A DC_PSU that was designed for interaction with the present invention. It has a dedicated control and monitoring connector with the required signals. It provides strong power delivery to the 12 V rails but in certain use cases insufficient for very power hungry graphics adapter(s) or multiple hard drives.

• PB: An external AC/DC switching power brick that delivers DC voltage between 6 V and 48 V (typically 12 V).

• AO: Add-On function with a remote-controllable soft-start switch circuit that listens to and transmits "power good"-information from and to the entire power delivery system. The AO function supplies power to a computer component, typically a graphics adapter or one or more hard drives. The AO function might be a separate board or an integral part of a unified power delivery system. The AO board typically contains an additional pass-through of power to the DC_PSU, which enables one standardized punch-out in the computer chassis. Unless explicitly expressed otherwise, the term AO stands for the soft-start switch part of the board - not the pass-through part. Classification of Graphics Adapters

GACl. Graphics adapter integrated in the CPU or on the motherboard

GAC2. Graphics adapter powered entirely from the PCI-Express bus (<= 75 W)

GAC3. Graphics adapter powered from PCI-Express bus and one 6-pin 12 V connector GAC4. Graphics adapter powered from PCI-Express bus and one 8-pin 12 V connector GAC5. Graphics adapter powered from PCI-Express bus and multiple 6- or 8-pin 12 V connectors

The above classes (defined by the inventor) are not set in stone. E.g., nVidia's current line of graphics adapters is specified as follows, however many of the manufacturers design for overclocking and add additional connectors:

• GTX 1060: 120 W using one 6-pin connector

• GTX 1070: 150 W using one 8-pin connector

• GTX 1080: 180 W using one 8-pin connector

Both the 6- and 8-pin connectors have 2 pins dedicated to signaling to the graphics adapter how much power the PSU can supply on each connector. In other words, only 2+2 or 3+3 pins actually carry the load current. (Half of the pins carry +12 V and the other half carries power ground.)

This invention is mainly relevant for GAC3 through GAC5.

Description

Components

1. Input stage with connector(s) for power to soft-start switch, optionally including DC/DC converter(s)

2. Soft-start switch, including monitoring sub-circuits such as Over-Voltage Protection (OVP), Under-Voltage Protection (UVP), Over-Current Protection (OCP), and possibly others

3. I/O connector and soft-start switch controller

4. Output connector(s) to graphics adapter, 12 V

5. Input stage with connector for power to DC_PSU, optionally including a DC/DC converter

6. Output connector to DC_PSU, 12 V

7. Power ground connection between DC_PSU and graphics adapter power paths

8. AC/DC power brick with one or more sets of cabling supplying a fixed 6 - 48 V (typically 12 V)

9. DC_PSU in the form of a stand-alone device

10. Graphics adapter

11. DC/DC converter for 6 - 48 V input into 12 V (typically multiphase step-down)

12. DC_PSU integrated on a common power delivery board

13. Part of a DC_PSU integrated on a common power delivery board

14. Output connector for connection to motherboard 20- or 24-pin ATX connector

15. Output connector for connection to motherboard 12 V connector

16. Motherboard

Connections

A. DC input from PB to DC_PSU supplying a fixed 6 - 48 V (typically 12 V)

B. DC input from PB to soft-start switched load supplying a fixed 6 - 48 V (typically 12 V) via one or more separate cablings.

C. Monitoring and control signals in and out

D. DC output to motherboard 20- or 24-pin ATX connector (typically 5 V standby, 3.3 V, 5 V, 12 V, and -12 V)

E. DC output to motherboard 12 V connector

F. DC output to DC_PSU, typically 12 V

G. DC output to graphics adapter (12 V) or hard drives (any combination of 3.3 V, 5 V, and 12 V)

H. AC input to PB, typically in the range of 90 to 265 V and 47 to 63 Hz.

Description of Figures

Fig 1. DC_PSU_M using an AO board for the pass-through function only. This is an example of an entry-level configuration for a GAC1 through GAC3 gaming computer that is prepared for easy upgrade to support a more powerful graphics adapter (fig. 2 or 3). With a DC_PSU_L this supports GAC1 and some GAC2 graphics adapters.

Fig 2. DC_PSU using an AO board both for pass-through and for soft-start switching of power to a GAC3 through GAC5 graphics adapter. In this example it is powered by one common PB with two sets of cabling (GAC3 or GAC4) or three sets (GAC5).

Fig 3. DC_PSU using an AO board both for pass-through and for soft-start switching of power to a GAC3 through GAC5 graphics adapter. In this example it is powered by two separate PBs with one set (DC_PSU) and one or two sets (graphics adapter) of cabling each. This is an example of re-use of pre-existing equipment.

Fig 4. DC_PSU using two AO boards, one of which for pass-through and both for soft-start switching of power to one GAC3 through GAC5 graphics adapter each, in Scalable Link Interface (SLI) or Cross-Fire configuration. In this example it is powered by one common PB with three sets of cabling (GAC3 or GAC4) or five sets (GAC5).

Fig 5. DC_PSU using two AO boards, one of which for pass-through and both for soft-start switching of power to one high-end graphics adapter each, in Scalable Link Interface (SLI) or Cross-Fire configuration. In this case it is powered by three separate PBs with one or two sets of cabling each. This is an example of re-use of pre-existing equipment, possibly an upgrade from fig. 3.

Fig 6. Example of alternative solution with DC/DC converter (11) that generates 12 V for graphics adapter(s), motherboard 12 V connector, and motherboard 20- or 24-pin ATX connector. A second DC/DC converter block (13) generates the rest of the DC_PSU voltages (5 V stand-by, 5 V, 3.3 V, and -12 V). It only incorporates soft-start switching of the 5 V rail. The 12 V output is inherently soft-started by the DC/DC converter (as is the 3.3 V output). It is powered by one single PB at 24 to 48 V. It is not in compliance with a requirement in standards IEC/EN/UL/CSA 60950 that limits the maximum possible power that may pass in a wire to 240 VA. It could be further equipped with Over-Current Protection (OCP) on each output rail, each signaling "power good" to the entire power delivery system. This would be in compliance with the 240 VA limitation.

Fig 7. Example of a modification to fig. 6 that complies with the 240 VA limitation. There is a soft-start switch circuit on every 12 V output.

Fig 8. Example of a modification to fig. 6 in which the common 12 V DC/DC converter has been broken up into several ones, each limited to 240 VA and inherently soft-started. Background Information

There are four main consumers of power in today's computer:

1. Motherboard: 3.3 V, 5 V stand-by, 5 V, 12 V, and -12 V fed into the 20- or 24-pin power connector on the motherboard

2. Motherboard: 12 V fed into a 4- or 8-pin power connector on the motherboard. This input often supplies power to the CPU and the PCI Express bus.

3. Graphics adapter: A gaming PC or graphics workstation needs a significant amount of 12 V power fed into one or a few 6- or 8-pin power connectors on the graphics adapter.

4. Hard drives and other peripherals: A suitable combination of 3.3 V, 5 V, and 12 V fed into one or more hard drives. For a file server with mechanical drives, a great deal of power is needed for the 12 V rail, especially at spin-up.

For the range of computers most relevant to this invention, the graphics adapter is the main consumer, followed by the motherboard CPU input. For file servers, the main consumer is the set of mechanical hard drives that in particular require much current on the 12 V rail when spinning up.

The power delivery system must meet the following requirements:

I. Facilitate synchronized turn-on and turn-off.

II. Meet rise-time and rise-order requirements for the rails.

III. Monitor the quality of the power delivered on every rail.

IV. Provide emergency shutdown of the entire system in case of a failure condition.

V. Provide power to either all rails or no rails (except for the 5 V stand-by).

The equipment might break if this is not enforced.

There is a requirement in the lEC/EN/UL/CSA 60950 standards that limits the maximum possible power that may pass in a wire to 240 VA.

The ATX and derived standards specify two signals for communication between the motherboard and the PSU, found on the 20- or 24-pin motherboard power connector:

• PS_ON#: To start and run the computer, the motherboard shorts this signal to ground, which causes the PSU to turn on the 3.3 V, 5 V, 12 V, and -12 V rails. (5 V stand-by is always on.) When this signal is connected to 5 V stand-by or open-circuited (thereby left pulled-up to 5 V stand-by), the PSU must turn off all rails except 5 V stand-by.

• PW _OK: The PSU stops shorting this signal to ground (thereby letting it be pulled up to 5 V stand-by) when the power is good on all rails. This tells the motherboard that it is safe to boot up and maintain normal operation. The PSU shorts this signal to ground in case of a failure condition (i.e. power is no longer good) which causes the motherboard to stop operating.

If PWR_OK goes low while PS_ON# is low, this is an alert of a failure condition to the rest of the modular power delivery system. Problem Description

There are currently two types of computer power supplies; the traditional AC_PSU metal box and the legacy DC_PSU (DC_PSU_L) connected to an external power brick (PB):

The AC_PSU is in widespread use and can be bought with sufficient power handling capability, even for very power-hungry computers. A drawback is that it is not upgradable - it's an atomic unit, so if you need a more powerful one, you must buy a new one to replace the old. It comes in a variety of shapes in accordance with one of the ATX-related standards, all of which are mounted inside the computer chassis, typically have a more or less noisy cooling fan, and limit the minimum size and design freedom of the computer chassis and the other components inside the box.

Commercially available AC_PSUs tend to require a significantly higher total power rating than what is actually needed by the computer system. This is a question of power distribution over the different power rails (too much made available to the 3.3 V and 5 V rails) and what seems to be an inability to sustain power delivery at great load current changes on the 12 V rail(s), especially at start-up. To some extent this need for over-dimensioning of AC_PSU power places the average load at a point where the efficiency is less than optimal, causing unnecessary losses.

The DC_PSU_L currently on the market is a step forward in the sense that most of the heat generation is moved to the external PB and that the part inside the computer chassis is much smaller. Having only the relatively small DC_PSU_L inside the chassis gives greater freedom when planning the placement (and available size) of the computer components. It is however too weak for gaming computers and file servers.

By implementing a series of design improvements, it is possible to increase the DC_PSU_L's capability so that it can be used for at least 6-disk file servers and GAC3 gaming computers. Some of these improvements consist of placing bulk capacitors within the DC_PSU (in addition to the ones in the PB) and soft-start switching the 12 V rail (as opposed to the commonly used instantaneous high-side turn-on of a P-channel MOSFET transistor which causes an inrush current that might force the PB into short-circuit protection). Adding a few additional improvements not further mentioned here, we have a device referred to as a DC_PSU_M.

This improved type of solution still suffers from a few natural limitations, most importantly the fact that the PB's feedback loop can only tolerate a certain (but unknown) amount of external bulk capacitance before it becomes unstable and unfit to use. Having only one power path from which all loads share the same cabling and external bulk capacitance means that at some point the different loads will drain the DC_PSU_M's energy storage and starve each other out. Even the small resistance and inductance in the cabling is too much of a hindrance to the load transients' sourcing current from the PB's bulk capacitors and output stage rather than starving the other loads. Solutions Enabled by the Invention

There are two possible types of solution to this problem drawn from the insight that the power handling capability can be increased as much as necessary so long as starvation is avoided:

• Soft-start switch controlled power paths separated all the way back to the output stage / bulk capacitors of the PB(s)

• Power conversion stage(s) immediately inside the computer chassis

These two approaches have different implications and properties. In both cases the main power is consumed on the 12 V rails into the different loads (including the 12 V rail leaving the DC_PSU itself). The anticipated common case is to supply one or more graphics adapters in this way, but the same principle also applies to file servers with more hard drives than the DC_PSU_M can support.

Please see Description of Figures for additional information. Separated Soft- Start Switch Controlled Power Paths

Each load gets its power from a path separated all the way back to the output stage / bulk capacitors of the PB(s), controlled by its own soft-start switch.

This is a truly modular approach with natural upgrade paths.

Fig. 1 through 5 illustrate various combinations and upgrade paths, starting with a system that has a GAC1 through GAC3 graphics adapter (fig. 1) so the AO board is only used for pass-through to the DC_PSU. When the user wants to upgrade to a more powerful graphics adapter, the actual AO board is taken into service (the soft-start switch part). Fig. 2 shows the case where one PB supplies both DC_PSU and AO board via separate cablings, while fig. 3 shows the pre-existing PB supplying the DC_PSU and an additional PB supplying the AO board.

Fig. 4 and 5 illustrate the next upgrade step, to using two graphics adapters in Scalable Link Interface (SLI) or Cross-Fire configuration. This requires additional AO board(s) and either more PB cabling or more PBs. This approach is scalable far beyond the use of two graphics adapters.

The power paths through the AO board can consist of more than one (typically no more than two) cablings and connectors in parallel, although the illustrations only depict one instance. The reason for this optional parallelization is presented below.

It is necessary to standardize these connectors and cablings between PB and AO board (including DC_PSU pass-through). It is practical and pedagogic to apply a 1:1 translation between the number of graphics adapter connectors and the number of PB cablings. This means a need for 3+3 pin power cablings, for which the standardized 6-pin PCI-Express connector (Molex part number 45559-0002) is a natural choice. Its pinout is unambiguous and its keying prevents incorrect mating. (A 1:1 translation is not strictly necessary. The number of pins and connectors on the graphics adapters seems to account for use of thinner wires and terminals that are not of high -current type.)

Like all connectors, they experience a temperature rise at the point where the male and female terminals attach. Also, the wires themselves heat up slightly. It is advisable to use thick high-quality wires and connector terminals rated for high current (e.g. Molex HCS). According to Molex specifications, up to 30 A can be supplied on one such HCS cabling and 3+3 connector set, but the temperature rise imposes a practical usable range not exceeding the 240 VA limit. The optional parallelization could be used to reduce power loss and temperature rise in use cases where a more powerful PB was bought than what was initially needed. It is essential to you only parallelize cablings from one PB for each power path. Connecting multiple PBs to the same power path could break the equipment (in particular the PBs) or result in erratic behavior.

Please note that with much smaller computer chassis and cleverly positioned AO board(s), the cables inside the box are much shorter than the ones used with an AC_PSU in a traditional computer chassis. A great fraction of theses cable and connector losses already occur in AC_PSU computers.

The combined voltage drop in the power path should be compensated for by supplying not 12.0 V but some 12.3 V. The ATX standard states 12 V +/- 5% but allows up +/- 10% at heavy load. So long as the 12 V lines always stay between 10.8 V and 13.2 V we're safe.

Each cabling output from the PB must have a 240 VA Over-Current Protection (OCP), which could be as simple as a fuse. As the AO board detects loss of input power and incorporates its own sophisticated OCP, the 240 VA requirement is met.

In order to establish and maintain a standard that is easily understood by the user and as far as possible avoids user errors, a consistent use of 12 V PBs is advised. A number of adapter cables interfacing legacy 12 V PBs to the modular connector should be developed, as the entire concept is based on reuse of pre-existing equipment.

It is quite possible to implement a DC/DC converter at the AO board power input(s) and maintain the modular approach, but if the point is to reuse PBs (e.g. from retired laptop computers) that supply another voltage (typically 16 V to 21 V), the number of connector types, polarizations, and potential user errors makes you think twice.

This approach can be used to augment power to both DC_PSU and AC_PSU. The DC_PSU_M is designed for this modular concept and the DC_PSU_L and AC_PSU can be used with an additional adapter board that provide the necessary signals (presented below).

Power Conversion Stage(s) Immediately Inside the Computer Chassis

This approach moves the effective output stage / bulk capacitors closer to the loads, as illustrated in fig. 6 through 8.

While this solution can be used with 12 V PBs, it makes most sense to utilize a higher input voltage (24 V or up to 48 V) into a main DC/DC step-down converter that outputs 12 V, eliminating or reducing the need for multiple sets of cabling. At some point you reach a voltage level that could be dangerous to humans and pets if they are exposed to open conduits.

If you want to take advantage of the possibility to use only one input connector, this more or less leaves you with a monolithic design of a series of products with different power rating. There is no clear upgrade path.

The DC/DC-converter incurs an additional cost, needs considerable space, and generates so much heat that it must be cooled by a fan. For high currents, a multi-phase design is more or less the only option, but it has inherently high low-load losses (unless EMI-noisy pulse-skipping or burst mode operation is used).

Fig. 6 and 7 show the use of one common very high-current DC/DC converter at the input, generating 12 V at up to some 50 A. In fig. 6 the DC/DC converter's inherent soft-start design means that the separate soft-start switches are not necessary for it to function. The problem is that this is in violation of the 240 VA limitation. You must add Over-Current Protection (OCP) on each load connector with monitoring of the output voltage and reporting these statuses to the whole power delivery system (not depicted). This brings you very close to fig. 7 in which the (monitored) soft -start switches are brought back.

In fig. 8 each output is supplied from its own soft-started DC/DC converter limited to 240 VA. Multiple DC/DC converters cause even higher conversion losses, need even more space, and cost even more money.

The PB needs roughly the same number of OCP functions as in the other approach, although protection should be provided per wire rather than per connector. As before, the individual PB OCP function could be a simple fuse.

Control, Monitoring, and Safety Circuits

A very important detail is the absolute need to incorporate synchronized start-up of all rails, adhering to rise-time and rise-order requirements. It is also necessary to monitor the quality of the power (voltage and current) delivered on each rail, with synchronized emergency shutdown of all rails in case of a failure anywhere in the power delivery system and prevention of start-up in the case when not all power path inputs are energized. Part of these safety measures are incorporated in the PSU, some in the motherboard, and some in the AO board. Each part of the power delivery system is responsible for monitoring its own power path, terminating power delivery in case it detects a failure, receiving the status from the other parts of the power delivery system, and transmitting its own status to the other parts, possibly also comprising a shutdown backup circuit as discussed below.

In some implementations it is beneficial to use the following four types of active-high signals with pull-up resistors to logic high (typically 5 V stand-by):

• PS_ON#: The ATX motherboard signals power on (low) or off (high or high-Z) to the PSU or a derivate thereof. At least one PSU supervisor integrated circuit (TPS3510) outputs a control signal (FPO#) that for the present application could be used to perform the same function as PS_ON#. FPO# is an example of a signal derived from PS_ON#.

• ENABLE: The inverted derivative of the PS_ON# control signal from the motherboard, such that it can be forced to ground in order to terminate ongoing operation (such as start-up and reboot prevention). It thus provides a means for emergency shutdown of all power delivery.

• PS_ON_P OTECTED#: The inverted ENABLE signal passed on to the PSU from the adapter board.

• PWR_OK: The ATX status indicator. It is pulled low by any part of the power delivery system when one of its rails fails to provide appropriate voltage and current. The motherboard reacts by terminating operation and releasing PS_ON#. The AC_PSU and the DC_PSU_L must use an adapter board connected between the motherboard 20- or 24-pin connector and the PSU connector. It inverts PS_ON# into ENABLE, inverts ENABLE into PS_ON_PROTECTED#, and brings out ENABLE, PWR_OK, and optionally PS_ON# signals to the control and monitoring connector. The DC_PSU_M is designed so that these three signals and connector are integrated on the DC_PSU_M itself, which means that an adapter board is not necessary.

Start-Up Prevention

By implementing a circuit that acts as a normally closed relay, it is possible to short ENABLE and PWR_OK to ground when the power input is not energized and to release these signals (to be pulled up) when the power input is energized. Alternatively, a P-channel depletion mode MOSFET performs the same function.

Equipment Protection in Case of Invalid Input Power Disconnection

A power failure mode that is unique to the modular design is the case of a DC power input connector being disconnected when the computer is running. The start-up prevention protection covers this case by abruptly turning off power delivery (by shorting ENABLE to ground), which should be sufficient for preventing equipment from breaking.

Power Delivery Failure Signaling and Emergency Shutdown

The PWR_OK signal is pulled low by any part of the power delivery system in case of a failure during normal on-going operation. This is detected by the motherboard that immediately releases PS_ON#, which turns off power delivery. This provides a form of inherent emergency shutdown.

It is possible but perhaps not necessary to implement a backup circuit in the AO board that pulls ENABLE low if the AO board detects PWR_OK going low while PS_ON# is held low by the motherboard (i.e. the moment just before the motherboard releases PS_ON#). In more detail:

1. The motherboard pulls PS_ON# low in order to start-up the computer. PWR_OK is initially held low by the power delivery system.

2. The power delivery system tries to start up all rails.

3. After a certain short period the safety feature checks the outcome:

a. If PWR_OK is still pulled low it means that there is a power delivery system failure.

ENABLE is pulled low until the motherboard releases PS_ON#.

b. If PWR_OK has gone high, the safety feature waits for PWR_OK going low. If this happens while PS_ON# is held low by the motherboard, ENABLE is pulled low until the motherboard releases PS_ON#.

So far it's simple. The thing is that many motherboards automatically retry indefinitely, which could be a problem in case of a hardware malfunction. The difficult question is whether an additional safety feature should be implemented; reboot prevention.

Reboot Prevention

Depending on what caused PWR_OK to be pulled low, a reboot can either be the most practical to the user or completely unwanted. If we had an Under-Voltage Condition (UVC) it could be because we were e.g. using a PB of insufficient power rating, tried over-clocking too aggressively, or experienced a short AC line drop. In these cases we want the computer to reboot automatically. On the other hand, if we had any type of error due to a breakdown in a component in the computer or in the power delivery system, we would want the entire power delivery system to remain shut off. As far as the inventor knows, AC_PSUs don't generally keep track of what went wrong, so they typically let the motherboard decide whether to reboot, which it seems to generally do.

The additional safety feature is an optional latch that keeps ENABLE low after the backup circuit has triggered. It's necessary to power cycle the input power of the part of the power delivery system that is holding the latch in order to make it release it. This is a new type of safety feature for computer power supplies.

Benefits

With this invention, it is possible to build very small and powerful gaming computers, graphical workstations, and file servers. The AC_PSU is no longer the only option, which frees valuable space inside the computer chassis and gives greater layout freedom in the chassis. It is easy to build standard-component computers that are 33 % to 50 % smaller by using the current invention. This reduces the computer to a size at which it is portable; a powerful gaming computer that is small enough to put in the hand luggage. As a further example, it can be placed by the living-room TV for social Virtual Reality (VR) gaming, in addition to all the present areas of use.

The modular concept makes it possible for the owner to upgrade from using only a DC_PSU and a PB without an AO board to using the same DC_PSU and PB together with one or more AO boards and PBs, simply adding equipment and not throwing away the pre-existing equipment. This is of great economic and environmental value. It is even possible to augment the power handling capability of an AC_PSU in this way.

Prior Art

• US7539023B2 (Monolithic plug-in power supply): This expired patent describes and only concerns the type of device referred to as DC_PSU_L in this text.

• US8878390B2 / US9223371B2 (Adaptor for adding a second power supply unit to a computer system): This patent concerns an adaptor board that enables plug-and-play parallelization of two or more individual and separate AC_PSU ATX power supplies through a daisy-chained series of adaptor boards. Each link in this chain contains one adaptor board and an additional AC_PSU. The adaptor board consists of a 4-pin legacy peripherals power connector to the AC_PSU in the previous link, a relay, and a 20- or 24-pin power connector for on/off control of the current link's additional AC_PSU. When the previous link powers up, it energizes the relay that pulls PS_ON# low and thereby powers up the current link's AC_PSU.

This patent is based on the use of two or more full-blown individual AC_PSUs. There is thus excellent separation between the rails, but rise-time and rise-order requirements are not met (or even considered). There is no way for a down-link AC_PSU to signal an error condition to the up-link AC_PSU(s), which means that an error condition might break the equipment due to some components being energized while others are not.

For these reasons, this type of configuration can only be used for peripherals that can be safely energized in solitude. Hard drives are one such example, but they are the only type of power-hungry peripherals for which one low-power AC_PSU might not be sufficient when a great number (>6) of hard drives are used. There is no PC computer chassis with room for more than one non-redundant AC_PSU on the market. It is not clear what problem this prior art is actually attempting to solve, but it can only be used for a problem that doesn't really exist. It will most likely never be incarnated as a usable product.

The conceptual design of this patent is essentially different compared to the add-on board described in the present application. While figures 4 and 5 in the present document support parallelization of multiple add-on boards, they are not daisy-chained but truly parallel on one common control and monitoring bus. The solution in the present document can safely be used for graphics adapters and CPU power as it incorporates all the necessary safety mechanisms and timing requirements. In the present application the power is routed through and switched inside the add-on board, while the prior art is switching only the control signal in the adaptor. Finally, the present document only adds the AC/DC power conversion to the voltage rails that are actually needed. The present document enables new market segments of smaller and quieter gaming computers, graphics workstations, and file servers. The prior art patent causes a need for a bigger PC chassis.

Other Publications

ATX12V Power Supply Design Guide, v2.31 (Power Supply Design Guide for Desktop Platform Form Factors, vl.2):

http://www.formfactors.org/developer/specs/Power_Supply_Design_Guide_Desktop_Platform_Rev _l_2.pdf

IEC/EN/UL/CSA 60950: http://www

Claims

1. A soft-start switch circuit, working in conjunction with a pre-existing computer power delivery system or being an integral part of such a system, for power delivery to at least one component of a computer, comprising at least one separated power supply path; wherein the soft-start switch circuit is configured to: receive command/s to activate or deactivate power delivery to the at least one computer component;

output a voltage ramped up to a fixed level to the at least one computer component on the at least one separated power supply path when the activation command is received; discontinue power delivery when the deactivation command is received; and receive and transmit a signal stating whether an adequate voltage and current level is received by the at least one computer component.

2. The soft-start switch circuit according to claim 1, further configured to discontinue power delivery when it detects a voltage or current delivery failure in its power path and transmit this information to the other parts of the power delivery system.

3. The soft-start switch circuit according to any of claims 1-2, wherein the output voltage is ramped up to 12 Volt when the power delivery is provided to at least one graphics adapter; and ramped up to any combination of 3.3 Volt, 5 Volt, and 12 Volt when the power delivery is provided to at least one hard drive.

4. The soft-start switch circuit according to any of claims 1-3, further comprising any combination of protection circuits for: start-up prevention by prohibiting the activation command when not all power inputs are energized; invalid power disconnection protection by enforcing the deactivation command when one power input loses power during on-going operation; emergency shutdown by enforcing the deactivation command when a signal stating power delivery failure is received; and reboot prevention by latching the enforced deactivation command when a signal stating power delivery failure is received, and by releasing this latch when the input power is cycled.

5. The soft-start switch circuit according to any of claims 1-4, wherein: the activation command is implemented as an active-high signal bus with pull-up to logic high, where activation is effectuated when no part of the power delivery system is forcing this signal low, further referred to as ENABLE; the deactivation command is implemented as the ENABLE signal being forced low; and prohibiting the activation command and enforcing the deactivation command both mean that the ENABLE signal is being forced low.

6. An add-on board comprising a soft-start switch circuit according to any of claims 1-5.

7. A computer power delivery system comprising at least one soft-start switch circuit according to any of claims 1-5.

8. A method by which a soft-start switch circuit, working in conjunction with a pre-existing computer power delivery system or being an integral part of such a system, is used for power delivery to at least one component of a computer, comprising: receiving command/s to activate or deactivate power delivery to the at least one computer component; outputting a voltage ramped up to a fixed level to the at least one computer component on the at least one separated power supply path when the activation command is received; discontinuing power delivery when the deactivation command is received; and receiving and transmitting a signal stating whether an adequate voltage and current level is received by the at least one computer component.

9. The method according to claim 8, further comprising: discontinuing power delivery when detecting a voltage or current delivery failure in its power path and transmitting this information to the other parts of the power delivery system.

10. The method according to any of claims 8-9, further comprising any combination of the following measures of protection:

providing start-up prevention by prohibition of the activation command when not all power inputs are energized; providing invalid power disconnection protection by enforcement of the deactivation command when one power input loses power during on-going operation; providing emergency shutdown by enforcement of the deactivation command when a signal stating power delivery failure is received; and providing reboot prevention by latching the enforced deactivation command when a signal stating power delivery failure is received, and by releasing this latch when the input power is cycled.

11. The method according to any of claims 8-10, further comprising: inverting the ATX standard control signal PS_ON# from the motherboard into an active-high pulled-up activation signal further referred to as ENABLE, or in any other way producing the ENABLE signal from a derivation of PS_ON# from for example, but not limited to, the output of a PSU supervisor circuit; inverting the ENABLE signal into a signal further referred to as PS_ON_P OTECTED# sent to the power supply control unit; and distributing the ENABLE signal as a bus to all parts of the power delivery system for synchronized activation and deactivation, thereby providing a means for any part of the power delivery system to force system-wide discontinuation of power delivery.

12. A system for power delivery to a plurality of components of a computer, comprising: a plurality of soft-start switch circuits according to any of claims 1-5; a plurality of computer components, each connected to a respective soft-start switch circuit according to any of claims 1-5, on a separated power path.