Jab kisi phone mein fast charging band ho jaye lekin normal charging chal rahi ho, BQ25975 wahi IC hai jo aap sabse pehle check karte hain. Ye Texas Instruments ka single-cell switched-capacitor charger IC hai, jo phone ke main charger IC (jaise BQ25890 ya BQ2589x series) ke sath mil kar kaam karta hai. Iska kaam simple hai: battery mein zyada current daalna, wo bhi minimum heat aur minimum cable loss ke sath.Traditional buck converter charger IC ek inductor use karta hai current step-down karne ke liye. BQ25975 alag tareeke se kaam karta hai — switched-capacitor (SC) architecture ke through. Is design mein input current, output current ka aadha hota hai, jabke output voltage input ka aadha hota hai. Matlab agar cable se 4A aa raha hai, battery ko 8A mil sakta hai. Ye trick charging cable aur connector par heat kam karti hai, jo fast-charging phones mein ek common failure point hota hai.Ye IC dual-phase design use karta hai — do switching phases jo alag-alag time par kaam karte hain. Isse ripple kam hota hai aur input/output capacitor requirement bhi kam ho jati hai. Board pe aapko iske around choti flying capacitors (CFL1, CFL2 type) milengi jo is switched-cap operation ke liye zaroori hain.BQ25975 pure IC-controlled hai, matlab isko I2C interface ke through host processor (phone ka PMIC ya application processor) control karta hai. Host hi enable/disable, protection thresholds, aur charging current set karta hai. Ye khud independently charging cycle start nahi karta jaisa BQ24075 jaisa standalone linear charger karta hai — is wajah se agar software ya PMIC side ka fault ho, to IC theek hone ke bawajood charging kaam nahi karegi.Protection ke liye ye IC input overvoltage/overcurrent, output overvoltage/overcurrent, aur temperature sensing (battery aur cable dono) integrate karta hai. Die temperature monitoring bhi built-in hai, jo thermal-related dead after flash cases mein important role play karta hai. In-built ADC bus voltage, bus current, output voltage, aur battery current jaise parameters ko real-time monitor karta hai — is data ko host software diagnostics ke liye use karta hai.Repair bench par is IC ka fault pattern kaafi specific hota hai: phone charge slow ho raha ho lekin heat na ho, ya "fast charging not supported" jaisa notification aaye jabke adapter aur cable dono theek hon, to BQ25975 ya iske associated flying capacitors suspect hote hain. Kabhi kabhi liquid damage ya static discharge se ye IC short ho jata hai, jiski wajah se board pe short-circuit reading milti hai VBUS ya VOUT line par.Reballing ya IC replace karte waqt hot air station ka temperature control zaroori hai, kyunki BQ25975 jaisi chhoti package wali IC ke around bohot saare passive components hote hain jo overheating se easily damage ho sakte hain. IC change karne ke baad, agar phone dead after flash ho jaye ya charging bilkul band ho, to pehle continuity check karo VBUS aur GND ke beech, phir board schematic se compare karo taake koi solder bridge na ho.Ye component un technicians ke liye zaroori hai jo fast-charging Android phones (Qualcomm Quick Charge, MediaTek Pump Express, ya USB PD PPS support karne wale models) ki charging board repair karte hain. Chipset-level compatibility phone ke main PMIC design par depend karti hai, is liye har board pe exact same configuration nahi milegi — lekin operating principle same rehta hai.
