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Li-Ion charger with MIC79050 (150580-I)

Status: In progress
February 16, 2017
<span>This design is based on the Micrel (=Microchip) MIC79050 Lithium Ion battery charger IC. An INA219 monitors the battery voltage and charge/discharge current flowing through shunt resistor R6. T1 switches the charger on and off. D1 and R2 are used for formatting deeply discharged batteries, T2 and R9 are used for discharging. Relay Re1 disconnects the battery in case of power failure.</span><br /><br /> Features:<br /> Battery formatting: when the battery voltage is lower than 2.7V, it will be charged with a maximum current of 20mA until 2.71V is reached. Then normal charging will start.<br /> Charging:<br /> The MIC79050 will limit the charging current to approx. 500mA. When the current drops below 80mA, the battery is considered charged and the charging process is stopped. The total energy is measured and displayed on the LCD (in mAh).<br /> Time-out function:<br /> After 30 hours of charging or formatting the process is terminated.<br /> Discharging:<br /> The battery is discharged with a 10 Ohm resistor until its voltage drops to 3.0V. The total energy (in mAh) is measured and displayed on the LCD.<br />  <br /> The LCD will display the following information:<br /> Total (dis-)charging time<br /> Current voltage and (dis)charging current<br /> Total energy in mAh<br /> Remaining charging time until time-out (hours)<br />  <br /> A bi-colour LED gives the following indications:<br /> Orange (both red and green on): battery formatting<br /> Red: charging current > 200mA<br /> Green: charging current between 80mA and 200mA<br /> Blinking red: discharging<br /> Off: no (dis)charging<br />   BOM Resistor R1 = 270 Ω, carbon film, 5%, 0.25W, 250V R2,R8 = 1 kΩ, carbon film, 5%, 0.25W, 250V R3 = 3.3 kΩ, carbon film, 5%, 0.25W, 250V R4,R5 = 4.7 kΩ, carbon film, 5%, 0.25W, 250V R6 = 100mOhm, 5%, 1W R7 = 1.5 kΩ, carbon film, 5%, 0.25W, 250V R9 = 10 Ω, carbon film, 5%, 2W, 350V P1 = 10 kΩ, trimmer, flat Capacitor C1,C2,C4 = 100 nF, 50 V, X7R, 5.08 mm pitch C3 = 100 µF, 50 V, 3.5 mm pitch, 8x11 mm C5 = 220 µF, 50 V, 5 mm pitch, 10x16 mm C6 = 1000 µF, 50 V, 7.5 mm pitch, 16x26 mm C7 = 33nF, 63V, PET, 5.08 mm pitch Inductor L1 = 100uH, 190mOhm, 900mA MCSCH895-101KU Semiconductor D1,D2,D3 = 1N4007, 1000 V, 1 A D4 = 1N5817, 20 V, 1 A, Vf=450 mV @ If=1 A T1 = FQP27P06X, -60 V, -27 A, 120 W, Vgs=-4 V, Rdson=70 mΩ T2 = IRF540NPBF, 100 V, 33 A, 130 W, Vgs=4 V, Rdson=44 mΩ LED1 = bi-colour LED red/green, 3-pin CC, L-3VEGW LED2 = LED, red, 3 mm IC1 = PIC16F1829-I/P EPS 150580-41 IC2 = Li-Ion battery charger MIC79050-4.2YS IC3 = Buck switching regulator LT1076CT-5 IC4 = Current sense amplifier INA219AIDR Other LCD1 = 2 x 20 character LCD with backlight LCD1 = 16-way boxheader K1 = Pin header, breakable, 1 row, 6-way, vertical K2,K3 = Terminal block 5.08 mm, 2-way, 630 V S1,S2 = Switch, tactile, 24 V, 50 mA, 6x6 mm RE1 = Relay, 5 V, SPST, 5 A Misc. PCB 150580-1 v2.0 16 way flatcable, 15cm + 2 x 16-way flatcable connectors NOTE: LED1, LED2, S1, S2 mounted on bottom side
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