eup8207-4.2/8.4/8.4a ds8207 ver 1.1 may 2011 1 switch mode li-ion/polymer battery charger description the eup8207 is a constant current, constant voltage li-ion battery charger controller that uses a curre nt mode pwm step-down (buck) switching architecture. with a 500khz switching frequency, the eup8207 provides a small, simple and efficient solution to fast charge one (4.2v) or two (8.4v) cell lithium-ion batteries. the eup8207 charges the battery in three phases: conditioning, constant current, and constant voltag e. an external sense resistor sets the charge current wit h 10% accuracy. an internal resistor divider and precisio n reference set the final float voltage to 4.2v per c ell with 1% accuracy. an internal comparator detects the nea r end-of-charge condition while an internal timer set s the total charge time and terminates the charge cycle. the eup8207 automatically re-starts the charge if the b attery voltage falls below an internal threshold, 4.05v pe r cell. the eup8207 also automatically enters sleep mode wh en dc supplies are removed. the eup8207 is available in the 8-lead sop and 10-l ead tdfn packages. typical operating performance 8 10 12 14 16 18 20 60 65 70 75 80 85 90 95 100 efficiency vs input voltage eup8207-8.4 vbat=7.0v vbat=8.0v (curves include input diode) efficiency(%) input voltage (v) features wide input supply voltage range: 4.8v to 20v C 4.2 version 8.9v to 20v C 8.4 version 8.9v to 20v C 8.4a version 500khz switching frequency end-of-charge current detection output 7 hour charge termination timer 1% charge voltage accuracy 10% charge current accuracy low 10a reverse battery drain current automatic battery recharge automatic trickle charging of low voltage batteries automatic sleep mode for low power consumption battery temperature sensing stable with ceramic output capacitor 8-lead sop and 10-lead tdfn packages rohs compliant and 100% lead (pb)-free applications small notebook computer portable dvd handheld instruments 5 10 15 20 60 65 70 75 80 85 90 95 100 efficiency vs input voltage eup8207-4.2 vbat=3.8v vbat=4.0v (curves include input diode) efficiency(%) input voltage (v)
eup8207-4.2/8.4/8.4a ds8207 ver 1.1 may 2011 2 typical application circuit figure 1. 1.5a single cell/2.0a dual cells li-ion battery charger
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