一、數字電位器芯片有哪些
數(shu)字(zi)(zi)電(dian)位(wei)器(DigitalPotenTIometer)亦(yi)稱數(shu)控(kong)可編程電(dian)阻(zu)器,是(shi)一(yi)種代替傳統機械(xie)電(dian)位(wei)器(模(mo)擬(ni)電(dian)位(wei)器)的新型CMOS數(shu)字(zi)(zi)、模(mo)擬(ni)混合信號處(chu)理(li)的集成電(dian)路。數(shu)字(zi)(zi)電(dian)位(wei)器由數(shu)字(zi)(zi)輸入控(kong)制,產生一(yi)個模(mo)擬(ni)量的輸出。依據數(shu)字(zi)(zi)電(dian)位(wei)器的不同,抽(chou)頭電(dian)流(liu)最大值(zhi)可以從(cong)幾百(bai)微安(an)到幾個毫安(an)。下面(mian)介紹幾種常用數(shu)字(zi)(zi)電(dian)位(wei)器芯片:
1、數字電位器MAX5432/5433
MAX5432/5433的端(duan)(duan)到端(duan)(duan)電(dian)(dian)阻分(fen)別為(wei)(wei)50kΩ及100kΩ,端(duan)(duan)到端(duan)(duan)的電(dian)(dian)阻溫度系數(shu)標稱值(zhi)為(wei)(wei)35ppm/℃,比(bi)例(li)溫度系數(shu)只有5ppm/℃,可應(ying)用于需要低溫度系數(shu)可變電(dian)(dian)阻的電(dian)(dian)路中,例(li)如低漂移、可編程增益放大器(qi)電(dian)(dian)路。芯片采用8引腳TDFN封裝(zhuang),具有一個散熱(re)功(gong)能(neng)的接地焊接點(dian)EP,將該(gai)點(dian)焊接在(zai)具有適(shi)當(dang)面積的印板銅皮上,使芯片可工作在(zai)-40℃:至+85℃擴展級溫度范圍(wei)。
2、數字電位器MAX5438
MAX5438是MAXIM公司生產(chan)的(de)7位(wei)(wei)128階(jie)數(shu)字電(dian)(dian)(dian)(dian)位(wei)(wei)器(qi)(qi)。它由1個7位(wei)(wei)移位(wei)(wei)寄存器(qi)(qi),1個7位(wei)(wei)數(shu)據鎖(suo)存器(qi)(qi),模塊,電(dian)(dian)(dian)(dian)位(wei)(wei)器(qi)(qi)和控(kong)制(zhi)時鐘邏(luo)輯組成。MAX5438的(de)控(kong)制(zhi)信(xin)號包括3個輸(shu)入(ru)(ru)信(xin)號:芯片選擇(/CS),數(shu)據輸(shu)入(ru)(ru)(DIN)和串行時鐘(SCLK),數(shu)字邏(luo)輯由一個2.7V~5.25V的(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)驅動(dong)。其內部電(dian)(dian)(dian)(dian)阻兩端的(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)由外(wai)部通過VDD及VSS提供,VDD與VSS之間的(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)必須大于(yu)9V小于(yu)31.5V。這使得MAX5838在輸(shu)入(ru)(ru)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)的(de)選擇上具有很大的(de)靈活性。同(tong)時,MAX5438的(de)外(wai)部電(dian)(dian)(dian)(dian)路非常(chang)簡單,幾乎不需要任(ren)何外(wai)接元件就可實(shi)現對(dui)輸(shu)入(ru)(ru)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)的(de)調節輸(shu)出(chu)。
二、數字電位器芯片選型的要點有哪些
選(xuan)擇(ze)數(shu)(shu)字(zi)電(dian)位(wei)器芯片(pian)應(ying)考慮(lv)的(de)方面很多,電(dian)位(wei)器的(de)個(ge)數(shu)(shu),滑片(pian)的(de)數(shu)(shu)目即有(you)多少級,電(dian)阻的(de)阻值,有(you)沒有(you)緩沖(chong)觸(chu)頭,能否記憶掉電(dian)時(shi)的(de)位(wei)置,封裝(zhuang)等。相似于3386電(dian)位(wei)器的(de)封裝(zhuang)及(ji)特點,總的(de)來說數(shu)(shu)字(zi)電(dian)位(wei)器芯片(pian)選(xuan)型主要(yao)還是從以下三(san)點進行(xing)考慮(lv)。
1、數字電位器抽頭的變化形式:系統(tong)重新通電時,阻(zu)值能夠恢(hui)復(fu)上一次掉電時的阻(zu)值,則要選(xuan)擇非易失性(xing)的數(shu)字電位器。
2、數字電位器電壓:帶緩(huan)沖器輸出的(de)電(dian)位器,輸出是一(yi)(yi)個電(dian)壓(ya)值,而不(bu)是一(yi)(yi)個電(dian)阻值,這時應該選(xuan)擇不(bu)帶緩(huan)沖器的(de)。
3、數字電位器分辨率:如果系統對分辨(bian)率要求比較高(gao),可選擇滑片數(shu)目多一些(xie)的電(dian)位器,或(huo)者(zhe)使用兩個數(shu)字電(dian)位器串聯達到其目的。