OVERVOLTAGE EFFECTS Junctions may be Forward Biased if the current is Limited In general a safe Current limit is 5mA Reverse Bias Junction Breakdown is Damaging Regardless of the current level When in Doubt, Protect with External Diodes and series Resistances Curve Tracers Can be Used to Check the Overvoltage Characteristics of a device Simplified Equivalent Circuits in Data Sheets do not tell the Entire Story!!! Figure 7.3 AMPLIFIER OUTPUT VOLTAGE PHASE REVERSAL Some operational amplifiers exhibit output voltage phase reversal when one or both of their inputs exceeds their input common-mode voltage range. Phase reversal is usually associated with JFET (n-or p-channel)input amplifiers, but some bipolar devices(especially single-supply amplifiers operating as unity-gain followers)may also be susceptible In the vast majority of applications, output voltage phase reversal does not harm the amplifier nor the circuit in which the amplifier is used. Although a number of operational amplifiers suffer from phase reversal, it is rarely a problem in system design. However, in servo loop applications, this effect can be quite hazardous. Fortunately, this is only a temporary condition. Once the amplifiers inputs return to within its normal operating common-mode range, output voltage phase reversal ceases. It may still be necessary to consult the amplifier manufacturer, since phase reversal information rarely appears on device data sheets. Summarized as follows is a list of recent vintage Analog devices amplifier products that are now including output voltage phase reve characterization/commentary: Single-Supply/ Dual Supply Rail-to-Rail OP295/OP495 OP282OP482 OP113/OP213/OP413 OP285 OP183/OP283 OP467 OP292OP492 OP176 OP191/OP291OP491 BUF04 AD820/AD822/AD824 OP193/OP293/OP4936 OVERVOLTAGE EFFECTS Junctions may be Forward Biased if the Current is Limited In General a Safe Current Limit is 5mA Reverse Bias Junction Breakdown is Damaging Regardless of the Current Level When in Doubt, Protect with External Diodes and Series Resistances Curve Tracers Can be Used to Check the Overvoltage Characteristics of a Device Simplified Equivalent Circuits in Data Sheets do not tell the Entire Story!!! Figure 7.3 AMPLIFIER OUTPUT VOLTAGE PHASE REVERSAL Some operational amplifiers exhibit output voltage phase reversal when one or both of their inputs exceeds their input common-mode voltage range. Phase reversal is usually associated with JFET (n- or p-channel) input amplifiers, but some bipolar devices (especially single-supply amplifiers operating as unity-gain followers) may also be susceptible. In the vast majority of applications, output voltage phase reversal does not harm the amplifier nor the circuit in which the amplifier is used. Although a number of operational amplifiers suffer from phase reversal, it is rarely a problem in system design. However, in servo loop applications, this effect can be quite hazardous. Fortunately, this is only a temporary condition. Once the amplifier’s inputs return to within its normal operating common-mode range, output voltage phase reversal ceases. It may still be necessary to consult the amplifier manufacturer, since phase reversal information rarely appears on device data sheets. Summarized as follows is a list of recent vintage Analog Devices amplifier products that are now including output voltage phase reversal characterization/commentary: Single-Supply/ Rail-to-Rail Dual Supply OP295/OP495 OP282/OP482 OP113/OP213/OP413 OP285 OP183/OP283 OP467 OP292/OP492 OP176 OP191/OP291/OP491 BUF04 OP279 AD820/AD822/AD824 OP193/OP293/OP493