OPA445 is a high-voltage field-effect transistor input operational amplifier 6

power loss

Power consumption depends on power supply, signal, and load conditions. For DC signals, power consumption is equal to the product of the output current and the voltage across the conductive output transistor, PD=IL（VS−VO）。 By using the lowest possible power supply voltage to ensure the required output voltage swing, power consumption can be minimized.

For resistive loads, the maximum power consumption occurs at half the DC output voltage of the power supply voltage. The loss of communication signals is lower. Application bulletin SBOA022 explains how to calculate or measure the dissipation of abnormal loads or signals.diode

OPA445 can provide an output current of 15mA or more. For standard operational amplifiers operating with a ± 15V power supply, this will not cause any problems. However, at high power supply voltages, the internal power consumption of operational amplifiers may be quite high. The operation of a single power source (or unbalanced power source) can generate greater power consumption because a larger voltage is applied to the conductive output transistor. Applications with high power consumption may require a heat sink.diode

heat dissipation

The power consumed in OPA445 will cause an increase in junction temperature. To ensure reliable operation, the maximum joint temperature should be limited to 125 ° C (150 ° C for to-99 packaging). Some applications require a heat sink to ensure that the maximum operating junction temperature is not exceeded. In addition, to improve reliability, the junction temperature should be as low as possible. The junction temperature can be determined by the following formula:diode

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The encapsulation thermal resistance JA is influenced by installation technology and environment. Poor air circulation and the use of sockets can significantly increase thermal resistance. The optimal thermal performance is achieved by soldering the operational amplifier onto a circuit board with wide printed circuit traces, allowing for greater conduction through the operational amplifier leads. A simple clip on heat sink (such as Thermalloy 2257) can reduce the thermal resistance of TO-99 metal packaging by up to 50 ° C/W. The SO-8 PowerPAD package will provide lower thermal resistance, especially for simple heat sinks with even lower heat dissipation. For more information on determining radiator requirements, please refer to Application Bulletin SBOA021.diode