US 5,289,118 AGranted

Programmer/tester with electronically switched bypass capacitor

AssigneeData I/O Corporation

InventorKellee J. Crisafulli

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Abstract

A circuit is disclosed for use in testing and programming electronic devices. The circuit provides an electronic wave of connecting bypass capacitors to selective device pins. The circuit includes first and second diodes that are coupled intermediate first and second bypass capacitors and a device node and to the second capacitor to charge the first and second capacitors. A current source is coupled to the first and second bypass nodes to forward bias a first and second diodes, thereby coupling the device node to the first and second capacitors. To selectively decouple the first and second bypass capacitors, voltage sources are coupled to the bypass node, thereby reverse biasing the first and second diodes and effectively disconnecting the first and second bypass capacitors from the device node.

Claims14

Dependent claims

A programmer/tester for programming semiconductor circuits of the type having a plurality of input/output pins and at least one pin designed to receive a supply voltage, said programmer/tester comprising:

data processing means for providing a bypass signal and a select signal, said data processing means being responsive to user provided input for selectively providing said bypass signal in first and second states;
socket means for receiving a semiconductor circuit, said socket means being constructed to couple a pin of the semiconductor circuit to a device node;
supply voltage means responsive to said select signal for supplying a voltage having a predetermined magnitude to said device node;
capacitor means for coupling a capacitance between a bypass node and a reference potential;
electrical source means responsive to said bypass signal for coupling a supply of electrical energy to said bypass node, said electrical source means being responsive to said first state of said bypass signal for coupling a supply of electrical energy to said bypass node to charge said capacitor means and being responsive to said second state of said bypass signal for coupling a predetermined potential to said bypass node;
and
diode means responsive to the charge stored by said capacitor means for conducting current between said bypass node and said device node so that the charge stored by said capacitor means stabilizes the voltage of said device node, said diode means being responsive to the predetermined potential supplied to said bypass node to substantially prevent conduction of current between said bypass node and said device node.

4 more elements

Apparatus for selectively bypassing a device node comprising:

data processing means for providing a bypass signal and a select signal, said data processing means being responsive to user provided input for providing said bypass signal in first and second states;
supply voltage means responsive to said select signal for coupling a supply voltage to the device node;
capacitance means for selectively storing charge to stabilize the voltage of the device node, said capacitance means being coupled to a bypass node means;
electrical source means responsive to said bypass signal for supplying electrical energy to said bypass node means, said electrical source means being responsive to said first state of said bypass signal for supplying electrical energy to said bypass node means to charge said capacitance means and being responsive to said second state of said bypass signal for supplying a predetermined voltage to said bypass node means;
and
diode means for selectively conducting current between said bypass node means and the device node, said diode means being responsive to the charge stored by said capacitance means for conducting current between said bypass node means and the device node so that the charge stored by said capacitance means stabilizes the voltage of the device node, said diode means being responsive to the predetermined voltage provided to said bypass node means by said electrical source means to substantially prevent conduction of current between said bypass node means and said device node.

3 more elements

Dependencies are inferred from the claim text.