【正文】
MAX235,MAX236,MAX240,和MAX241都同時(shí)擁有三態(tài)控制線和一個(gè)低功耗的關(guān)斷控制器。通常卸載的轉(zhuǎn)換速率是24V/μs,當(dāng)滿載3Ω和2500pF為10V/μs。這個(gè)對(duì)定期喚醒系統(tǒng)去工作是很重要的。當(dāng)所有發(fā)射器都被禁用時(shí),該設(shè)備進(jìn)入關(guān)斷模式。 MAX225提供5個(gè)發(fā)射器和5個(gè)接收器,而MAX245提供10接收器和8發(fā)射器。該ENRA和ENRB接收器輸入端每個(gè)都能控制4個(gè)接收器輸出端。ENTA,ENTB都處于邏輯高電平時(shí)該設(shè)備進(jìn)入關(guān)斷模式,發(fā)射器進(jìn)入三態(tài)模式。MAX248提供了8個(gè)接收器和帶有四個(gè)控制引腳的8個(gè)驅(qū)動(dòng)器。驅(qū)動(dòng)器輸出端進(jìn)入高阻抗?fàn)顟B(tài)(三態(tài)模式)。在這種情況下。接收器有三個(gè)操作模式:全速接收(正常激活),三態(tài)門(使能端),低功耗接收端(接收器繼續(xù)以較低的數(shù)據(jù)傳輸速率繼續(xù)發(fā)揮作用)。 25V的輸入,并供應(yīng)5kΩ電阻。該驅(qū)動(dòng)器輸出漏極電流仍然低于1uA,即使發(fā)射極輸出電壓在0V和6V之間(電源電壓為+6V)。15V。5V。當(dāng)在外部電路時(shí)電源從V+到V時(shí)不要將V+和V接到一點(diǎn),違反了EIA/TIA232E接口的最小輸出電壓177。每個(gè)TTL/CMOS驅(qū)動(dòng)轉(zhuǎn)換的輸入和TIA/EIA232F同一水平。5V EIA/TIA232E driver output voltage when sourcing current from V+ and V to external circuitry.When using the shutdown feature in the MAX222,MAX225, MAX230, MAX235, MAX236, MAX240,MAX241, and MAX245–MAX249, avoid using V+ and V to power external circuitry. When these parts are shut down, V falls to 0V, and V+ falls to +5V. For applications where a +10V external supply is applied to the V+ pin (instead of using the internal charge pump to generate +10V), the C1 capacitor must not be installed and the SHDN pin must be tied to VCC. This is because V+ is internally connected to VCC in shutdown mode.RS232 DriversThe typical driver output voltage swing is 177。8V when loaded with a nominal 5kΩ RS232 receiver and VCC =+5V. Output swing is guaranteed to meet the EIA/TIA232E and specification, which calls for 177。在德州儀器LinASIC庫該驅(qū)動(dòng)器,接收器和電壓發(fā)生器起到了主要作用。5V。這些條件有阻值最小為3kΩ負(fù)載,最高工作溫度。在關(guān)斷模式電源電流通常降至8μA。發(fā)射極端的二極管和1kΩ的電阻串聯(lián)之后接地。這明顯的表明了轉(zhuǎn)換輸出帶有緩慢移動(dòng)的輸入信號(hào),即使有適量的噪聲和振鈴。該接收器能夠在全速接收和三態(tài)模式下進(jìn)行輸入控制。當(dāng)關(guān)斷時(shí),接收器作為沒有滯后的CMOS逆變器。對(duì)于MAX225,所有的5個(gè)接收器都是有ENR輸入控制的,對(duì)于MAX245,其中的八個(gè)輸出端接收器是由ENR輸出端控制的,剩余的兩個(gè)(RA5和RB5)仍然是活動(dòng)的。該ENRA和ENRB接收器每個(gè)輸入端都能控制4個(gè)接收器輸出端。這部分沒有始終激活的接收器。 MAX247提供了9個(gè)接收器和帶有四個(gè)控制引腳的8個(gè)驅(qū)動(dòng)器。與所有其他設(shè)備一樣,SHDN(MAX241的SHDN)也禁用接收器輸出端。發(fā)射器能夠在關(guān)斷模式下進(jìn)行輸入控制。低功耗接收模式MAX223,MAX242和MAX245,MAX249低功耗接收模式的特點(diǎn):當(dāng)電路處于關(guān)斷模式時(shí),仍然允許它接收信息。該驅(qū)動(dòng)器輸出轉(zhuǎn)換速率是有限的,按EIA/。將未使用的輸入端連接到GND或Vcc上。未被使用的驅(qū)動(dòng)器不工作這是因?yàn)?00kΩ輸入上拉電阻接到VCC(除MAX220)。當(dāng)這部分被關(guān)閉時(shí),V下降到0V,V+下降到+5V,10V的外部電源應(yīng)接到V+引腳上(而不是使用內(nèi)部電荷泵產(chǎn)生的10V),C1電容不需要接并且SHDN引腳必須接到VCC上。雙電荷泵電壓轉(zhuǎn)換器該MAX220MAX249有兩個(gè)內(nèi)部電荷泵能將RS232驅(qū)動(dòng)從+5V轉(zhuǎn)換為177。15V. The power supply current typically drops to 8μA in shutdown mode. The MAX220 does not have pullup resistors to force the outputs of the unused drivers low. Connect unused inputs to GND or VCC.The MAX239 has a receiver threestate control li