Kubva pane PCB marongero emagetsi, bepa iri rinounza yakanakisa pcb marongero nzira, mienzaniso uye matekiniki ekugadzirisa mashandiro eiyo nyore switch switch simba module.

Paunenge uchironga marongero emagetsi, chekutanga chekutarisa inzvimbo yemuviri yekutenderera kwemaviri ari kuchinjisa zvishwe zvazvino. Although these loop regions are largely invisible in the power module, it is important to understand the respective current paths of the two loops because they extend beyond the module. In loop 1 shown in Figure 1, the current self-conducting input bypass capacitor (Cin1) passes through the MOSFET to the internal inductor and output bypass capacitor (CO1) during the continuous conduction time of the high-end MOSFET, and finally returns to the input bypass capacitor.

Schematic diagram of loop in the power module www.elecfans.com

Figure 1 Schematic diagram of loop in power module

Loop 2 is formed during the turn-off time of the internal high-end MOSFEts and the turn-on time of the low-end MOSFEts. Simba rakachengetwa mukati inductor inoyerera kuburikidza nekubuda kubudikidza capacitor uye yakadzika magumo MOSFEts usati wadzokera kuGND (ona Mufananidzo 1). The region where two loops do not overlap each other (including the boundary between loops) is the region with high DI/DT current. Iyo yekupfuura yekupfuura capacitor (Cin1) inoita basa rakakosha mukupa yakakwira frequency iripo kune iyo inoshandura uye ichidzosera iyo yakakwira frequency yazvino kune yayo kwainobva nzira.

Iyo inobuda inodarika capacitor (Co1) haitakure yakawanda AC yazvino, asi inoshanda seyepamusoro-frequency firita yekuchinja ruzha. Nezvikonzero zviri pamusoro, zvekuisa uye zvinobuda ma capacitors zvinofanirwa kuiswa padhuze nepadhuze neVIN yavo uye VOUT mapini pane module. Sezvinoratidzwa muMufananidzo 2, iyo inductance inogadzirwa neiyi yekubatanidza inogona kuderedzwa nekugadzira iyo wiring pakati peapass capacitors uye avo akasiyana VIN uye VOUT mapini akapfupika uye akapamhama sezvinobvira.

Mufananidzo 2 SIMPLE SWITCHER chiuno

Kuderedza inductance muPCB dhizaini kune maviri makuru mabhenefiti. Kutanga, gadziridza kuita kwechikamu nekusimudzira kuchinjisa kwesimba pakati peCin1 neCO1. Izvi zvinovimbisa kuti module ine yakanaka hf yekupfuura, ichideredza inductive magetsi epamusoro nekuda kweiyo yakakwira DI / DT yazvino. Inoderedzawo ruzha rwechigadzirwa uye nemhepo kushungurudzika kuti uve nechokwadi chekushanda. Chechipiri, deredza EMI.

MaCapacitors akabatana neasina kusarudzika infasiti inductance anoratidza yakaderera impedance hunhu kune akakwirira maficha, nokudaro achidzikisa akaitisa mwaranzi. Ceramic capacitors (X7R or X5R) or other low ESR type capacitors are recommended. Kuwedzera kwekuisa ma capacitors anogona kungouya mukutamba kana mamwe ma capacitors akaiswa padhuze neGND uye VIN magumo. The Power module of the SIMPLE SWITCHER is uniquely designed to have low radiation and conducted EMI. However, follow the PCB layout guidelines described in this article to achieve higher performance.

Circuit current path planning is often neglected, but it plays a key role in optimizing power supply design. In addition, ground wires to Cin1 and CO1 should be shortened and widened as much as possible, and bare pads should be directly connected, which is especially important for input capacitor (Cin1) ground connections with large AC currents.

Pini dzakadzika (kusanganisira mapads asina chinhu), yekuisa uye yekubuda ma capacitors, akapfava-kutanga ma-capacitors, uye mhinduro dzinodzivisa mumojuli idzi dzinofanira kunge dzakabatana neyakaiswa chiuno paPCB. Iyi tambo yakatenderera inogona kushandiswa senzira yekudzoka ine yakanyanya kuderera inductance zvazvino uye sechinhu chekupisa kupisa chinokurukurwa pazasi.

NGUVA. 3 Schematic dhizaini yem module uye pcb seyakashongedzwa impedance

Mhinduro yekudzivisa inofanirawo kuiswa padhuze nekukwanisika kune iyo FB (mhinduro) pini yemu module. To minimize the potential noise extraction value at this high impedance node, it is critical to keep the line between the FB pin and the feedback resistor’s middle tap as short as possible. Available compensation components or feedforward capacitors should be placed as close to the upper feedback resistor as possible. For an example, see the PCB layout diagram in the relevant module data table.

For AN example layout of LMZ14203, see the application guide document AN-2024 provided at www.naTIonal.com.

Heat Dissipation Design Suggestions

Iyo compact dhizaini yemamojuru, nepo ichipa magetsi mabhenefiti, ine kukanganisa kwakashata pane kupisa kupisa dhizaini, uko kwakaenzana simba rinodzingwa kubva kune madiki Spaces. To address this problem, a single large bare pad is designed on the back of the Power module package of the SIMPLE SWITCHER and is electrically grounded. Iyo padhi inobatsira kupa yakanyanya kudzikama yekupisa impedance kubva mukati meMOSFEts, iyo inowanzo gadzira yakawanda yekupisa, kune iyo PCB.

Iyo yekupisa impedance (θJC) kubva kune semiconductor junction kuenda kune yekunze package yezvigadzirwa izvi 1.9 ℃ / W. Ipo kuzadzikisa indasitiri-inotungamira θJC kukosha kwakanakira, yakaderera θJC kukosha haina musoro kana iyo thermal impedance (θCA) yepakeji yekunze kumhepo yakakura kwazvo! If no low-impedance heat dissipation path is provided to the surrounding air, the heat will accumulate on the bare pad and cannot be dissipated. So what determines θCA? The thermal resistance from bare pad to air is completely controlled by the PCB design and associated heat sink.

Now for a quick look at how to design a simple PCB without fins, figure 3 illustrates the module and PCB as thermal impedance. Because the thermal impedance between the junction and the top of the outer package is relatively high compared to the thermal impedance from the junction to the bare pad, we can ignore the θJA heat dissipation path during the first estimate of the thermal resistance from the junction to the surrounding air (θJT).

Nhanho yekutanga mukupisa dhizaini dhizaini ndeyekuona huwandu hwesimba rinobviswa. Simba rinodyiwa neiyo module (PD) inogona kuverengerwa nyore kushandisa giraidhi inoshanda (η) yakaburitswa mutafura yedata.

We then use the temperature constraints of the maximum temperature in the design, TAmbient, and the rated junction temperature, TJuncTIon(125 ° C), to determine the thermal resistance required for the packaged modules on the PCB.

Chekupedzisira, isu takashandisa yakareruka fungidziro yeiyo yepamusoro inoratidzira kupisa kupisa pamusoro pePCB pamusoro (isina kukanganiswa 1-ounce mhangura zvimbi uye akawanda kupisa singi maburi pane ese epamusoro neepasi pasi) kuona iyo ndiro nzvimbo inodiwa pakupisa kupisa.

Iyo inodiwa pcb nzvimbo yekufungidzira haifunge nezve iro basa rinoitwa nehunodzi dissipation maburi ayo anotamisa kupisa kubva kumusoro kwesimbi sara (iyo package yakabatana nePCB) kune yepasi simbi yakaturikidzana. Iyo yepasi yakatetepa inoshanda seyechipiri pamusoro penzvimbo iyo iyo convection inogona kuendesa kupisa kubva pahwendefa. Anokwana masere kusvika gumi maburi anotonhorera anofanirwa kushandiswa kuti nzvimbo yekufungidzira ive inoshanda. Iko kupisa kwekushisa kweye kupisa singi kunofungidzirwa neinotevera equation.

Kufungidzira uku kunoshanda kune yakajairwa kuburikidza-gomba remamirimita gumi nemaviri dhayamita ine 12 oz yemhangura yewallwall. Semaburi anodziya mazhinji senzvimbo inokwanisika anofanirwa kugadzirwa munzvimbo yese iripazasi peiyo isina chinhu, uye aya maburi ekupisa anofanirwa kuita rondedzero ine nzvimbo inosvika 1 kusvika 1.5mm.

kugumisa

Iyo SIMPLE SWITCHER simba module inopa imwe nzira kune akaomesesa magetsi magetsi dhizaini uye akajairwa pcb magadzirirwo ane hukama neDC / DC vashanduri. Nepo marongero ezvimisikidzo abviswa, rimwe basa reinjiniya richiri kuda kuitwa kuti rikwanise kuita kwemoduli nekupfuura kwakanaka uye kupisa kupisa dhizaini.