一、數字電位器芯片有哪些
數(shu)(shu)(shu)字電(dian)(dian)位(wei)器(qi)(qi)(DigitalPotenTIometer)亦稱數(shu)(shu)(shu)控可編程(cheng)電(dian)(dian)阻器(qi)(qi),是(shi)一種(zhong)(zhong)代替傳統機械電(dian)(dian)位(wei)器(qi)(qi)(模擬電(dian)(dian)位(wei)器(qi)(qi))的(de)(de)新型CMOS數(shu)(shu)(shu)字、模擬混合信(xin)號處理的(de)(de)集(ji)成電(dian)(dian)路(lu)。數(shu)(shu)(shu)字電(dian)(dian)位(wei)器(qi)(qi)由數(shu)(shu)(shu)字輸入(ru)控制,產生(sheng)一個模擬量(liang)的(de)(de)輸出(chu)。依據數(shu)(shu)(shu)字電(dian)(dian)位(wei)器(qi)(qi)的(de)(de)不同,抽頭電(dian)(dian)流最大值可以(yi)從(cong)幾(ji)百微安到幾(ji)個毫安。下面介紹幾(ji)種(zhong)(zhong)常用數(shu)(shu)(shu)字電(dian)(dian)位(wei)器(qi)(qi)芯片:
1、數字電位器MAX5432/5433
MAX5432/5433的(de)端(duan)(duan)到端(duan)(duan)電阻(zu)(zu)分別為(wei)50kΩ及100kΩ,端(duan)(duan)到端(duan)(duan)的(de)電阻(zu)(zu)溫(wen)(wen)度(du)系數標(biao)稱值為(wei)35ppm/℃,比例(li)溫(wen)(wen)度(du)系數只(zhi)有5ppm/℃,可(ke)應用(yong)(yong)于(yu)需要低溫(wen)(wen)度(du)系數可(ke)變電阻(zu)(zu)的(de)電路中,例(li)如低漂移、可(ke)編程增益放(fang)大器電路。芯片采(cai)用(yong)(yong)8引腳TDFN封(feng)裝,具(ju)有一個散熱功(gong)能的(de)接地(di)焊接點EP,將該點焊接在具(ju)有適當面(mian)積的(de)印板銅皮(pi)上,使芯片可(ke)工作在-40℃:至+85℃擴展(zhan)級溫(wen)(wen)度(du)范圍。
2、數字電位器MAX5438
MAX5438是(shi)MAXIM公司生產(chan)的7位(wei)(wei)128階數(shu)字電(dian)位(wei)(wei)器(qi)。它由(you)1個(ge)7位(wei)(wei)移位(wei)(wei)寄存(cun)器(qi),1個(ge)7位(wei)(wei)數(shu)據鎖存(cun)器(qi),模塊,電(dian)位(wei)(wei)器(qi)和控制(zhi)時(shi)鐘邏輯組成。MAX5438的控制(zhi)信號包(bao)括3個(ge)輸(shu)入(ru)信號:芯(xin)片選擇(/CS),數(shu)據輸(shu)入(ru)(DIN)和串(chuan)行時(shi)鐘(SCLK),數(shu)字邏輯由(you)一個(ge)2.7V~5.25V的電(dian)壓(ya)(ya)驅動。其內(nei)部(bu)(bu)電(dian)阻(zu)兩端的電(dian)壓(ya)(ya)由(you)外(wai)部(bu)(bu)通過VDD及VSS提供,VDD與(yu)VSS之間的電(dian)壓(ya)(ya)必(bi)須大(da)于9V小于31.5V。這使得MAX5838在(zai)輸(shu)入(ru)電(dian)壓(ya)(ya)的選擇上(shang)具(ju)有(you)很大(da)的靈活性。同時(shi),MAX5438的外(wai)部(bu)(bu)電(dian)路非常(chang)簡單,幾乎不需要任何(he)外(wai)接(jie)元件就(jiu)可實(shi)現對輸(shu)入(ru)電(dian)壓(ya)(ya)的調節輸(shu)出。
二、數字電位器芯片選型的要點有哪些
選(xuan)擇數字電(dian)(dian)(dian)(dian)位(wei)(wei)器(qi)(qi)(qi)芯片(pian)應考(kao)慮的方面(mian)很多,電(dian)(dian)(dian)(dian)位(wei)(wei)器(qi)(qi)(qi)的個數,滑(hua)片(pian)的數目(mu)即有多少(shao)級,電(dian)(dian)(dian)(dian)阻(zu)的阻(zu)值,有沒有緩沖觸頭(tou),能否記憶掉(diao)電(dian)(dian)(dian)(dian)時的位(wei)(wei)置,封(feng)裝(zhuang)等。相似于(yu)3386電(dian)(dian)(dian)(dian)位(wei)(wei)器(qi)(qi)(qi)的封(feng)裝(zhuang)及特點,總的來說數字電(dian)(dian)(dian)(dian)位(wei)(wei)器(qi)(qi)(qi)芯片(pian)選(xuan)型主(zhu)要還是從以下三點進行考(kao)慮。
1、數字電位器抽頭的變化形式:系統重新(xin)通電(dian)時,阻(zu)值能夠恢復上一次掉電(dian)時的(de)阻(zu)值,則要選擇非(fei)易(yi)失性的(de)數字電(dian)位(wei)器。
2、數字電位器電壓:帶緩(huan)(huan)沖器(qi)(qi)輸(shu)出的電(dian)位(wei)器(qi)(qi),輸(shu)出是一(yi)(yi)個電(dian)壓(ya)值,而不(bu)是一(yi)(yi)個電(dian)阻值,這時應該選擇(ze)不(bu)帶緩(huan)(huan)沖器(qi)(qi)的。
3、數字電位器分辨率:如果系統對分辨率要求(qiu)比(bi)較高,可(ke)選擇滑片(pian)數目多一些的(de)電(dian)位器,或者(zhe)使用兩(liang)個(ge)數字(zi)電(dian)位器串聯達到(dao)其目的(de)。