Truman Posted August 31, 2011 Report Share Posted August 31, 2011 Dear all,i have two questions about the OPA445.First, about the "package-lead", there are 4 kind of the package,"DIP-8", "SO-8 Surface-Mount", "SO-8 PowerPAD" and "TO-99 8-Pin".What's the difference in the performance between these 4 kinds of the package?The second question is, recently, I bought a OPA445AP to design a power amplifier.The power amplifier is chose to be inverting power amplifier.The input resistor and output resistor are 3M Ohm and 12M Ohm, so the gain is 12M/3M=4 if neglecting the minus sign. According to the datasheet of OPA445, the supply voltages of OPA445 could as high as +/- 45V.However, when applying +/- 40V, in addition to the output signal is disappeared from the oscillator scope, the temperature of the OPA445AP is quite high.But, when applying +/-30V, the performance is quite well and the temperature is moderate.So, what's the problem in the OPA445 or my circuit ?Is anyone can help me?Thank you very much.Truman Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 31, 2011 Report Share Posted August 31, 2011 I have two questions about the OPA445:1) First, about the "package-lead", there are 4 kind of the package,"DIP-8", "SO-8 Surface-Mount", "SO-8 PowerPAD" and "TO-99 8-Pin".What's the difference in the performance between these 4 kinds of the package?The datasheet lists their thermal resistance differences.2) The second question is, recently, I bought a OPA445AP to design a power amplifier.The power amplifier is chose to be inverting power amplifier.The input resistor and output resistor are 3M Ohm and 12M Ohm, so the gain is 12M/3M=4 if neglecting the minus sign. According to the datasheet of OPA445, the supply voltages of OPA445 could as high as +/- 45V.However, when applying +/- 40V, in addition to the output signal is disappeared from the oscillator scope. The temperature of the OPA445AP is quite high. Quote Link to comment Share on other sites More sharing options...
Truman Posted September 2, 2011 Author Report Share Posted September 2, 2011 The datasheet lists their thermal resistance differences.==> Thank you.The temperature of the OPA445AP is quite high. Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 2, 2011 Report Share Posted September 2, 2011 The very high stray capacitances of a breadboard connector tracks to each other and to the many connecting wires causes modern high frequency opamps to oscillate at a high frequency which causes them to get hot.A breadboard was fine with a lousy old (43 years old) 741 opamp that has poor high frequency response. Quote Link to comment Share on other sites More sharing options...
crystal1108 Posted October 14, 2011 Report Share Posted October 14, 2011 Sorry for that questions i hardly can reply for you, but i think the best answer is from the salers, why not you just go to the electronic mall to get the answers or you can search them by internet and then call them.here's some suppliers in hqew.net for opa445 TELESKY INTERNATIONAL LIMITED 0755_83957245 [email protected] SHENHONGBAO INTERNATIONAL (HK) COMPANY LIMITED 86-755-23467858 [email protected] Sky-micro Electronics co.,limited 86-0755-83237277 [email protected] Ariat Technology Ltd 0852_30522530 [email protected] SUNWAY INTERNATIONAL ELECTRONICS CO.,LTD 0755_83002266 [email protected] i wish that will help you .... Quote Link to comment Share on other sites More sharing options...
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