Integrated circuit that can be externally tested through a normal signal output pin
First Claim
1. A circuit arrangement that can be externally tested through an output pin, comprising an integrated circuit that comprises:
- a signal output pin;
a circuit unit having a test signal output;
a control unit having a testing input connected to said signal output pin for testing a potential at said signal output pin, and having a control output providing a control signal responsive to the testing of the potential; and
a switching element having a signal input connected to said test signal output of said circuit unit, a switched signal output connected to said signal output pin, and a control input connected to said control output of said control unit.
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Accused Products
Abstract
An integrated circuit can be tested externally at its normal signal output pin(s) without requiring additional testing output pins or test measuring pads. The integrated circuit includes a circuit unit that generates a normal output signal provided to the signal output pin in a normal operating mode and generates a test signal in a testing mode, a switching element that selectively does or does not connect the test signal from the circuit unit to the signal output pin, and a control unit that controls the switching element with a control signal responsive to the potential level present at the signal output pin. When the circuit is to be tested, a defined voltage is applied to the signal output pin by a voltage divider formed of resistors between a supply voltage and a reference voltage. This causes the control unit to close the switching element.
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Citations
16 Claims
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1. A circuit arrangement that can be externally tested through an output pin, comprising an integrated circuit that comprises:
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a signal output pin;
a circuit unit having a test signal output;
a control unit having a testing input connected to said signal output pin for testing a potential at said signal output pin, and having a control output providing a control signal responsive to the testing of the potential; and
a switching element having a signal input connected to said test signal output of said circuit unit, a switched signal output connected to said signal output pin, and a control input connected to said control output of said control unit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A circuit arrangement that can be externally tested through an output pin, comprising an integrated circuit that comprises:
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a signal input pin;
a signal output pin;
a circuit unit having a signal input connected to said signal input pin, a normal signal output connected to said signal output pin, and a first test signal output;
a first switching element having a first signal input connected to said first test signal output, a first switched signal output that is connected to said signal output pin and selectively switched relative to said first signal input, and a first switch control input;
a control unit having a testing input connected to said signal output pin, and a first control output connected to said first switch control input, wherein said control unit is adapted to provide at said first control output a first control signal responsive to a potential level existing at said signal output pin; and
a load resistor connected between a supply voltage and said signal output pin. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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Specification