JPH051908B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pseudo electronic load device suitable for testing the characteristics of DC power supplies for various electronic devices.

When testing the characteristics of a DC power supply for various electronic devices, conventionally, instead of connecting the actual electronic device as a load to the DC power source, a pure resistance such as a sliding resistor is connected as a pseudo load. When using such a pseudo load, there are advantages such as its simple configuration and the ability to freely change the size of the load.
When testing the output rise characteristics when the power is turned on or the output fall characteristics when the power is turned off, the test results differ depending on whether an actual electronic device is used as the load or when a pseudo load made of pure resistance is used. There will be a big difference between the two.

The present invention makes it easy to change the configuration and size (power consumption) of the load, and when subjected to a characteristic test of a DC power supply for electronic equipment, the test results are almost the same as when an actual electronic equipment is used as the load. The purpose of this study is to realize a pseudo-electronic load device that provides the following characteristics.

FIG. 1 is a diagram for explaining the basic configuration of an embodiment of the present invention, where T ₊ and T _- are DC power supply connection terminals, EL is a pseudo electronic load circuit element,
D _IEL is the current detection circuit of the pseudo electronic load circuit element EL,
COM is a comparison circuit, AMP is an error amplifier, CON is a current control circuit, and D _ICON is a current detection circuit of the current control circuit CON, and these constitute the pseudo electronic load device of the present invention.

When connecting a DC power supply to terminals T ₊ and T _- , the terminals
The current flowing in from T ₊ and T _- is shunted to the pseudo electronic load circuit element EL and the current control circuit CON, and each shunt current is detected by the detection circuits D _IEL and D _ICON , and the comparison circuit
The difference between the detection current of the detection circuit D _IEL and the detection current of the detection circuit D _ICON is detected at COM, and this detection signal is sent to the current control circuit via the error amplifier AMP.
The circuit impedance of the current control circuit CON is changed so that the ratio of the magnitudes of the detected currents of the detection circuits D _IEL and D _ICON becomes an arbitrary value.

For example, by using a transistor/transistor logic circuit element as the pseudo electronic load circuit element EL, the DC voltage applied to terminals T ₊ and T _- , the total current flowing through the pseudo electronic load circuit element EL and the current control circuit CON, and The relationship between is made non-linear rather than proportional, and the current detection circuit
If the circuit configuration and circuit constants of D _ICON are appropriately set so that the current detection ratio is 1/N, a pseudo electronic load device equivalent to the case where N pseudo electronic load circuit elements EL are connected in parallel can be configured. I can do it.

FIG. 2 is a diagram showing an embodiment of the present invention, in which T ₊
and T _- are DC power supply connection terminals, and EL ₁ is a pseudo electronic load circuit element, such as a transistor/transistor logic circuit element. V _CC and GND are the DC power supply connection pins, OPA ₁ and OPA ₂ are operational amplifiers (OPA ₁ and OPA ₂ operating power supply connection terminals, OPA ₂ feedback element, etc. are omitted), TR is for current control. The transistor, _R1 is a negative feedback resistor, _R2 is a current detection resistor, and these constitute the pseudo electronic load device of the present invention.

If the amplification degree A ₁ of the operational amplifier OPA ₁ is sufficiently large, the connection point a to the non-inverting input terminal and the connection point b to the inverting input terminal will be at the same potential, so the DC power supply connection terminals T ₊ and T _- When a DC voltage V is applied to
A DC voltage V is applied to the circuit element _EL1 . The current flowing through the circuit element EL ₁ is I ₁ , the current flowing through the current control transistor TR is I ₂ , the amplification degree of the operational amplifier OPA ₂ is A ₂ , and the resistance values of the resistors R ₁ and R ₂ are R ₁ and
Expressed by R ₂ , the current I ₂ flowing through the transistor TR is detected as a voltage drop across the resistor R ₂ ,
This detection voltage is negatively fed back to the input side of the operational amplifier OPA ₁ via the operational amplifier OPA ₂ and _the resistor R ₁ , and the transistor
Control is performed so that the internal impedance of the TR changes and the relationship I ₂ =R ₁ /R ₂ ·I ₁ /A ₂ is maintained. If the total current flowing from the DC power supply connection terminals T ₊ and T _- to the load side is I ₀ , then I ₀ = I ₁ + I ₂ = I ₁ + R ₁ /R ₂・I ₁ /A ₂ = I ₁ (1 + R ₁ /R ₂ · I/A ₂ In the above equation, if 1+R ₁ /R ₂ ·I/A ₂ =N, then I ₀ =I ₁ ·N.

In this embodiment, since the circuit element EL ₁ is formed of a transistor/transistor logic circuit element, the relationship between the DC voltage V applied to the terminals T ₊ and T _- and the total current I ₀ flowing through the load side is non-linear. It exhibits linearity and is closer to the state in which an actual electronic device is used as a load compared to the conventional case of using pure resistance. Also, the resistance values of resistors R ₁ and R ₂ , operational amplifier
By appropriately adjusting the amplification degree A ₂ of OPA ₂ and setting N to an appropriate value, a pseudo-electronic load device equivalent to an arbitrary number of circuit elements EL ₁ , that is, N pieces connected in parallel, can be realized. You can.

The above embodiment can obtain test results that are much closer to actual electronic equipment as a load than a conventional pseudo load made of pure resistance, but actual electronic equipment uses transistors, transistor logic circuits, etc. For example, diode transistor logic circuits,
Integrated circuits mainly composed of MOS field effect transistors, high-speed logic circuits composed of emitter-coupled transistors, various memory circuits, large-scale integrated circuits composed of various integrated circuit groups, individual transistors, diodes, resistors, capacitors, coils, etc. The embodiment shown in FIG. 2 cannot be said to be fully satisfactory as a pseudo load when compared with actual electronic equipment having such a complicated circuit configuration.

FIG. 3 is a diagram showing an embodiment of the present invention _that can realize a pseudo electronic load device that is almost equivalent to an actual electronic device that has an extremely complicated circuit configuration _.
are DC power supply connection terminals, EL ₁ to EL _o are pseudo electronic load circuit elements, EL ₁ is, for example, a transistor/transistor logic circuit element, EL ₂ is, for example, a diode/transistor logic circuit element, and EL ₃ to EL _o are also Each consists of appropriate electronic circuit elements. OPA ₂₁ or OPA _2o , OPA _AD and
OPA _NF is an operational amplifier, TR is a current control transistor, R ₂₁ to R _2o , R' ₂₁ to R' _2o , and R _NF are negative feedback resistors, and R _D is a current detection resistor. A load device is configured.

Amplification A ₂₁ of each operational amplifier OPA ₂₁ to OPA2n
or A _2o shall be sufficiently large, and the terminals T ₊ and
The total current flowing to the load side when a DC power supply is connected to T _- is I ₀ , the current flowing to each load circuit element EL ₁ to EL _o is I ₂₁ to I _2o , and each negative feedback resistor R' ₂₁ to
The current flowing through the R′ _2o circuit is I′ ₂₁ or I′ _2o , the current flowing through the negative feedback resistor R _NF is I _NF , the current flowing through the transistor TR is I _TR , and the amplification degree of the operational amplifier OPA _NF is A _NF
Then, I′ ₂₁ +I′ ₂₂ +…+I′ _2o =I _NF I ₂₁・R ₂₁ /R′ ₂₁ +I ₂₂・R ₂₂ /R′ ₂₂ +… +I _2o・R _2o /R′ _2o =A _NF / R _NF I _TR・R _D I _TR =R _NF /A _NF・R _D (I ₂₁・R ₂₁ /R′ ₂₁ +I ₂₂・R ₂₂ /R′ ₂₂ +…+I _2o・R _2o /R′ _2o ) I Since ₀ = I ₂₁ + L ₂₂ +…+I _2o +I _TR , I ₀ = L ₂₁ (1+R _NF R ₂₁ /A _NF R _D R′ ₂₁ ) +I ₂₂ (1+R _NF R ₂₂ /A _NF R _D R′ ₂₂ ) +...+I _2o (1+R _NF R _2o /A _NF R _D R' _2o ) In the above formula, 1+R _NF R ₂₁ /A _NF R _D R' ₂₁ =N ₁ 1+R _NF R ₂₂ /A _NF R _D R' ₂₂ =N ₂ … 1+R _NF R _2o /A _NF R _D R′ _2o =N _o , then I ₀ =I ₂₁ N ₁ +I ₂₂ N ₂ +…+I _2o No _o Therefore, N ₁ or N _o By selecting an appropriate value, it is possible to configure a pseudo electronic load circuit equivalent to N ₁ to N o load circuit elements _{EL 1} to EL _o connected in parallel, and load circuit elements EL ₁ to EL By forming each of _o using appropriate circuit elements, it is possible to construct a pseudo electronic load device that closely resembles an actual electronic device.

[Brief explanation of drawings]

Figures 1 to 3 are diagrams showing an embodiment of the present invention, in which T ₊ and T _- : DC power supply connection terminals, EL and
EL ₁ to EL _o : Pseudo electronic load circuit element, D _IEL and D _ICON : Current detection circuit, COM: Comparison circuit,
AMP: error amplifier, CON: current control circuit, V _CC
and GND: DC power supply connection pin, OPA ₁ , OPA ₂ ,
OPA ₂₁ to OPA _2o , OPA _AD and OPA _NF : operational amplifier, TR: current control transistor, R ₁ ,
_R21 to _R2o , _R'21 to _R'2o and _RNF : negative feedback resistors, _R2 and _RD : current detection resistors.

Claims (1)

[Scope of Claims] 1. A DC power supply connection terminal to which any number of series circuits consisting of a pseudo electronic load circuit element and a current detection circuit of this pseudo electronic load circuit element are connected in parallel, a current control circuit, and a current of this current control circuit. a series circuit connected to the DC power supply connection terminal; a summation current of the detection current of the current detection circuit of each of the pseudo electronic load circuit elements; and a detection current of the current detection circuit of the current control circuit. , and an operational amplifier circuit that outputs a circuit impedance control signal of the current control circuit.