Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Reexamination Certificate
1999-10-25
2001-01-30
Riley, Shawn (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
Reexamination Certificate
active
06181117
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns a power supply circuit of an electronic component in a test machine.
The invention can be applied advantageously for tests, in production or determination of voltage vs. current characteristics, for example, for mixed CMOS components (analog/digital) with an extremely high integration scale, and more particularly those components functioning with high currents, such as microcontrollers or microprocessors.
BAKGROUND OF THE INVENTION
Generally speaking, an electronic component test machine is mainly made up of three elements:
a computer which is the working station enabling an operator to prepare, using an appropriate software, the test sequences he intends to conduct on the electronic components, such as at the output of a production chain, so as to check its correct functioning;
the core of a test machine, commonly known as an electronic bay, connected to the computer and which comprises a certain number of elements for generating the test sequence prepared by the operator and for comparing the responses obtained to those provided in advance in the context of a conforming functioning of the components, and
a measuring head for housing the electronic components to be tested.
Moreover, the electronic bay includes a direct current supply sub-unit formed of as many power supply circuits as needed for supplying power to the components to be tested. Each power supply circuit is intended to provide the electronic component in question with a direct supply of current from a given range under a nominal polarization voltage, such as +5V. Depending on the type of components to be tested, there are various current ranges characterizing the power supply circuits: there are circuits with an extremely weak current in the range of 0 to 0.5 A, low current circuits with current in the range of 0.5 to 4 A, high current circuits with current in the range of 4 to 30 A, and very high current circuits with current in the range of 30 to 60 A.
The power supply circuits currently used having a given range are made up of two identical elementary circuits able to provide under the same nominal polarization voltage a direct current of half the given range, the output terminals of said elementary circuits being connected electrically in parallel and the current applied to the electronic components to be tested. For example, so as to obtain a power supply circuit with a range having an 8 A maximum, it is thus possible which are to place two elementary circuits in parallel low current circuits each having a range with a 4 A maximum.
More specifically, each elementary power supply circuit firstly includes a regulation circuit intended to ensure that the voltage effectively applied to the component is always equal to the nominal polarization voltage, and secondly a power circuit controlled by said regulation circuit whose designated aim is to provide a direct current of half the given range, the total current being the sum of the currents provided by the two elementary circuits, namely in principle double the current provided by each of them.
However, this type of assembly where the two elementary power supply circuits are completely independent does have a certain number of drawbacks.
Firstly, on static functioning, the two elementary power supply circuits are independent regulation circuits which, owing to dispersions of various origins (components, cable length to the measuring head), do not adjust the polarization voltage identically and this causes an erratic functioning of one circuit with respect to the other possibly leading to a situation where an elementary power supply circuit delivers a current into the other elementary power supply circuit with the risk of destroying the other elementary power supply circuit by means of thermal runaway without this malfunctioning being noticed by the user.
Secondly, on dynamic functioning, the presence on each regulation circuit of an independent compensation network with the decoupling capacitor placed on the supply pin of the component being tested can cause uncontrolled frequency stability problems due to the disparity between the two compensation networks. As a result, polarization voltage oscillations may occur and become unacceptable owing in particular to risks of excess heating of the component.
This difficulty linked to balancing between the two elementary circuits is much more sensitive when it is sought to embody power supply circuits needing to function within a range of extremely high currents extending up to 60 A. In fact, owing to the extremely high level of integration reached today, the present trend is to obtain a reduction of the nominal polarization voltage, namely a consequence of a reduction of the size of the components, and also an increase of the runaway current, namely a consequence of increasing their number.
One solution to embody a power supply circuit with an extremely high current would be to only use a single circuit with a single adjustment and a single power circuit. In fact by its very definition, no problem of balancing between elementary circuits could occur. However, other difficulties would appear, especially as regards connectors, as it would be necessary to be able to simultaneously use a larger number of pins. In addition, as the link with the component to be tested is effected over a large distance, namely about 6 meters, so as to avoid a significant ohmic fall occurring, it would be necessary to use a large diameter cable, which is incompatible as regards questions of spatial requirements in relation to existing installations. Finally, components functioning under extremely high power do pose significant cooling problems.
SUMMARY OF THE INVENTION
The solution offered by the invention is to use two elementary power supply circuits, as in the prior art previously described, provided however that the problems concerning balancing by the presence of two independent elementary circuits are resolved.
To this effect, one aspect of the present invention provides a power supply circuit of an electronic component in a test machine and intended to provide said component with a direct supply current from a given range under a nominal polarization voltage, said power supply circuit including two identical elementary power supply circuits, each able to provide on an output terminal a direct supply current from half the given range under said nominal polarization voltage, said output terminals being connected in parallel at the tested electronic component, said elementary power supply circuits each comprising:
a regulation circuit for maintaining on the electronic component a polarization voltage equal to the nominal polarization voltage,
a power circuit adapted to be controlled by said regulation circuit and for providing said direct supply current from half the given range,
this arrangement being characterized in that the regulation circuit of a first elementary power supply circuit known as the master circuit also controls the power circuit of the second elementary power supply circuit known as the slave circuit, the power circuit of said slave circuit being disconnected from the regulation circuit of the same slave circuit.
Thus, the adjustment of the polarization voltage is ensured by a single adjustment circuit, namely that of the master circuit. Thus, the causes of static and dynamic instability mentioned earlier are eliminated. Of course, so as to obtain a perfect sharing of the current between the master and slave circuits, it is essential that the power circuits are as identical as possible and that the gain, offset and thermal shift between the two circuits are as small as possible with respect to the balance sought between the currents. Note that if a significant variation occurs at a given moment, such as a current variation, this would be equally supported by the two circuits.
It is also necessary to observe that even if the two elementary circuits do not play a symmetrical role, they are nevertheless identical, which allows for a standardization of production of
Iafrate Gilles
Mallet Jean-Pascal
Petit Roland
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Riley Shawn
Schlumberger Systemes
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