Voltage Regulator Failure Analysis

Gideon Analytical Laboratories received one TI TPS767D301 dual-output low-dropout voltage regulator with a ground to reset short The TI TPS767D301 offers a transient response, low dropout voltages, and dual outputs. It is designed primarily for DSP applications. It features extended temperature performance from 55 to 125 degrees Celsius, drop out voltage typically 350 mV at 1 A, and enhanced product-change notification. The goal was to determine why these TI TPS767D301 voltage regulators were failing, paying special attention to the ground to reset short.

Gideon Analytical Laboratories received a JanTXV1N821 Zener diode for electronic failure analysis. A diode is a two-terminal electronic component with asymmetric conductance; it has low (ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the other. A semiconductor diode is the most common type of diode; it is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. A Zener diode is a diode which allows current to flow in the forward direction in the same manner as an ideal diode but also permits it to flow in the reverse direction when the voltage is above a certain value, known as the breakdown voltage. Zener diodes are semiconductor diodes which have been manufactured to have their reverse breakdown occur at a specific, well-defined voltage. The JanTXV1N821 diode is a surface mounted diode with a voltage selection range between 6.2 and 6.55 V. Its operating temperatures are between -65° C and 175º C, has tin-lead plated leads and comes in a hermetically sealed glass case. The JanTXV1N821 diode tested open. The goal was to identify the cause of the failure.

Gideon Analytical Laboratories received six pulse transformers, three of which were failures, three of which were reliable. The objective was to determine the cause of the failures and inspect the unused transformers for anything that could contribute to the cause of failures. Transformers are devices that transfer electric energy from one circuit to another, usually with a change in voltage. Pulse transformers are transformers optimized for transmitting rectangular electrical pulses. Ideally, pulse transformer designers try to minimize voltage droop, rise time, and pulse distortion. Gideon Analytical Laboratories conducted a thorough failure analysis on these pulse transformers.

Gideon Analytical Laboratories received two linear adjustable monolithic silicon 5962-89981 adjustable positive regulators both with no measurable output for failure analysis. A third device was sent with a questionable output. This is a three terminal positive adjustable voltage regulator designed to provide 1.5A with higher efficiency than conventional voltage regulators. The device is designed to operate to 1 Volt input to output differential and the dropout voltage is specified as a function of load current. The device is in a TO-257 hermetic package where Military applications require small size and high reliability.