模拟设计的100条经典经验！ 开关电源设计制作学习园地.mht

收集的模电的一些资料

            un-stable RF devices can be made stable by loading the input =
or the=20
            output by a simple resistor, either in series or parallel. =
<BR>46/=20
            You trade gain for bandwidth. <BR>47/ Push-pull power =
invertors=20
            using bipolars are risky and can saturate the core because =
of=20
            hysteresis stepping (use power fets) <BR>48/ The Al value of =
a core=20
            will increase up to 50% or more under current transients. =
<BR>49/ Be=20
            aware of leakage inductance when switching. V=3DL(dI/dt) =
<BR>50/ The=20
            harder you turn-on a power transistor, the longer it will =
take to=20
            turn off.( the part where you burn the joules in the device) =
<BR>51/=20
            Always remember the Miller guy. <BR>52/ In fault-finding a =
circuit,=20
            don"t overlook the obvious. (is there power?) <BR>53/ What =
is a=20
            ground loop, and how to avoid it. <BR>54/ 120 is a better =
number=20
            than 240 when using LM3XX type adjustable regulators. =
<BR>55/ The=20
            lower comparator in the old 555 may have quite a long =
storage time.=20
            <BR>56/ ZERO-ESR caps may do more harm than good. <BR>57/ A=20
            correctly configured audio power amplifier will give more =
distortion=20
            in Class-AB, not less, because of the abrupt gain changes =
inherent=20
            in switching from A to B every cycle. <BR>58/ Be a STAR when =
it=20
            comes to ground matters. <BR>59/ Know when you need to use a =
Zobel=20
            network. <BR>60/ Use current mirrors and mirror your =
current.=20
            <BR>61/ Heatsink eff decreases with height above sealevel. =
<BR>62/ A=20
            matt-black heatsink is much better than a shiny one. <BR>63/ =

            Ignoring secondary breakdown can be costly. <BR>64/ =
Understand fuses=20
            and fuse ratings, fast and slow. Do you know when to use a=20
            semiconductor-fuse? <BR>65/ Charge balancing resistors are a =
must=20
            when stacking serie-parallel high voltage capacitor banks. =
<BR>66/=20
            You must understand DC-restoration otherwise you will have a =
hard=20
            time designing Z-modulation in CRT circuits.<BR>67/ Display =
6 vert=20
            div low freq on a scope, increase the freq (make sure the =
source is=20
            constant amplitude) until display drops to 4.2 div. That is =
the true=20
            3dB BW of the scope. (scope-source impedance should be =
matched)=20
            <BR>68/ Doing a measurement with your DMM in the ACV =
position on=20
            your DC circuit will give a quick indication of any excess =
ripple on=20
            the supply when you don"t have a scope at hand. <BR>69/ Dly =
timebase=20
            on a scope is very useful once you figured out when, why and =
how to=20
            use it. <BR>70/ Know what to expect before you measure, =
otherwise=20
            any measurement is meaningless. <BR>71/ Op amps. Output will =
swing=20
            in the direction that will force the inv-input level to try =
come=20
            closer to the non-inv input level. <BR>72/ Understand =
virtual=20
            ground, slew-rate, CMRR and PSRR. (CMRR decrease with =
increase in=20
            freq) <BR>73/ Making measurements near a spec-analalyzer"s =
noise=20
            floor will give 3dB errors. <BR>74/ Understand the =
phase-noise=20
            limitations of the analyzer when making such measurements on =

            oscillators. <BR>75/ In a LC oscillator add some C with -ve =
temp=20
            coef to cancel the +ve temp coef of the L for min drift with =

            temp.<BR>76/ Less drift will result from making C with a few =

            parallel caps, to reduce the heating effect of the =
oscillating=20
            current when spread out over a larger plate area. &nbsp; =
&nbsp;=20
            &nbsp; 77/ You will get more tuning range with the same LC=20
            combination in a Clapp than in a Colpitts circuit. <BR>78/ =
High-Q=20
            tuned LC filters will have more insertion loss. <BR>79/ =
Williams"s=20
            Rule (Guru at Linear Tech) for precision op amp circuits: " =
Always=20
            invert (except when you can"t)" <BR>80/ Cuk is not a kind of =

            locomotive. <BR>81/ If you don"t know how to make a design =
better,=20
            find out what makes it worse. <BR>82/ Sometimes you know =
just enough=20
            to be dangerous. <BR>83/ Impedance will reflect back as the =
square=20
            of the turns ratio. <BR>84/ If you could design a component =
with the=20
            characteristics of a finger it could cure many design =
problems and=20
            you will be rich. <BR>85/ Get nervous when the customer you =
are=20
            trying to help doesn"t even have a scope. <BR>86/ Specs =
quoted by=20
            reps always exceed those by Engineering. <BR>87/ A bad =
(Engineer)=20
            workman always blames his tools. <BR>88/ Don"t believe =
everything=20
            that a SPICE program spits out. <BR>89/ It is easy to get =
the color=20
            code of a 1kOhm and 12Ohm resistor mixed up when you are in =
a hurry.=20
            <BR>90/ I bet one could write a thesis about the ability of =
probes=20
            to get tangled-up on a bench. <BR>91/ DMM can upset =
sensitive=20
            circuits from noise generated inside it. <BR>92/ When =
probing=20
            directly on a crystal of a uP, use 10kOhm or so resistor in =
series=20
            with the probe tip to prevent loading from stopping the osc. =
<BR>93/=20
            It is easier to see what is happening on the ports using a =
scope=20
            when you trigger one chan against the cpu clock. <BR>94/ =
National=20
            once made a bad op amp many years ago that some Engineers =
referred=20
            to it as "Jelly Beans" <BR>95/ The moment you can start to =
notice=20
            distortion on an oscilloscope it is already way past being=20
            acceptable. <BR>96/ Be big enough to say "I don"t know", =
people will=20
            respect you more. <BR>97/ The best designer is often working =
in the=20
            marketing department. <BR>98/ Some remarkable =
discoveries/inventions=20
            were made by people that knew very little about the subject. =
Don"t=20
            fall into a groove in you thinking process. <BR>99/ The=20
            Peter-Principle : Everybody will be promoted up to his own =
level of=20
            incompetence. <A =
href=3D"http://pespmc1.vub.ac.be/PETERPR.html"=20
            target=3D_blank>http://pespmc1.vub.ac.be/PETERPR.html</A> =
<BR>100/=20
            END-Enjoy=20
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          <TD class=3Dsmalltxt colSpan=3D5><FONT color=3Dred>[=C2=A5 =
=D6=F7]</FONT> |=20
            <B>Posted:</B> 2009-01-14 23:55</TD>
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