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USB 1.1 PHY Speed Control (Read 3187 times)
qiushidaren
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MOSFET!

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Chengdu
USB 1.1 PHY Speed Control
Jul 06th, 2010, 7:28pm
 
Hi all,

I am studying USB 1.1 PHY IC design now, but the speed control confuses me. I am modifying another guy's circuit, in this circuit, the part of speed control doesn't get an op amp to control the rise and fall times, it just uses the speed control pin to open or close an NMOS connecting to an inverter by a res and a PMOS connecting to an inverter by a res. Could anyone give me some suggestions about this?

-Terry
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supermoment
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Re: USB 1.1 PHY Speed Control
Reply #1 - Jul 7th, 2010, 1:07am
 
The res is to meet the termination spec, around 40-45ohm.
Is the control pin controlling the predriver or driver?
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