L6474的过热问题

我发现即使在1.4安培下，L6474的运行也非常热。它在一块不错的PCB上，有20块板，背面有一个小散热片（1英寸×1英寸），在不到2分钟的时间里它会上升到110℃。它也是power36包。我的PS电压是42伏。


我的电荷泵电压约为8伏。无论我是否使用3.3伏稳压器在外部为逻辑供电都无关紧要。

我已经花了很多精力来设计这个小型控制器，但按照这个速度，我可能不得不转向更好的芯片。
我过去使用的是L6207，在2安培/相位和45伏电压下非常酷。这是更大的24 powerDip

为什么ST会使这个芯片变得如此之小并且具有高导通电阻的mosfet？更大的芯片会更好。我甚至无法想象使用带有小型TSSOP封装的L6474H。
如果ST采用更大的引脚间距制造这种芯片，我相信客户。会更开心额定电压为3安培和45伏特的电机芯片非常大。为什么芯片必须是微观的？



以下为原文




I'm finding that the L6474 runs terribly hot even at 1.4 amps . Its on a decent PCB with 20 plates thru tholes a small heatsink (1'' x 1'') on the back and it will rise to 110 C in less than 2 minutes . It is the power36 package too.  My PS voltage is 42 volts.


  My charge pump voltage is about 8 volts. And it doesn't matter much whether i power the logic externally with a 3.3 volt regulator or not.  

  I've put a lot of effort into designing this small controller , but at this rate i may have to move to a better chip.  
  I've used the L6207 in the past and it ran very cool at 2amps/phase and 45 volts.  It was the larger 24 powerDip  

  Why would ST make this chip so small and have mosfets with a high on resistance ?  A larger chip would have been alot better. I can't even imagine using the L6474H with the tiny TSSOP package.   
  If ST made this chip in a much larger package with wider pin spacing , i'm sure customers. would be happier. The motor a chip rated at 3 amps and 45 volts is quite big. Why does the chip have to be microscopic ?