Fujitsu MB3887 manual AC Adaptor Voltage Detection, Operation Timing Diagram

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MB3887

■AC ADAPTOR VOLTAGE DETECTION

•With an external resistor connected to the +INE2 terminal (pin 3) , the IC enters the dynamically-controlled

charging mode to reduce the charge current to keep AC adapter power constant when the partial potential point A of the AC adapter voltage (VCC) becomes lower than the voltage at the −INE2 terminal.

AC adapter detection voltage setting : Vth

Vth (V) = (R1 + R2) / R2 ⋅ −INE2

<Error Amp2>

	−INE2
	4	−
VCC	A	+
VCC	3	+
R1	+INE2
R2

■OPERATION TIMING DIAGRAM

Error Amp2 FB2

Error Amp1 FB1

2.5 V

Error Amp2 FB3

1.5 V

OUT

	Constant voltage control	Constant current control	AC adapter dynamically-
			controlled charging

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Contents Package FeaturesDescription MB3887 PIN Assignment TOP ViewPin No Symbol Descriptions PIN DescriptionBlock Diagram Parameter Symbol Conditions Rating Unit Min Max Absolute Maximum RatingsParameter Symbol Conditions Value Unit Min Typ Recommended Operating ConditionsBol Min Typ Electrical CharacteristicsParameter Sym Pin Conditions Parameter Sym Pin Conditions Value Unit Bol Min Typ Max Parameter Sym Pin Conditions Value Unit Bol Min Typ OUT = −45 mA Output block Resistor Typical Characteristics Triangular wave oscillation frequency fOSC kHz Error amplifier gain and phase vs. Frequency Gain a Power dissipation vs. Ambient temperature Functional Description Power PWM comparator block PWM Comp Output block OUT Control block CTLSetting the Charging Voltage Method of Setting the Charging CurrentMethod of Setting the Triangular Wave Oscillation Frequency Soft-start block SoftMethod of Setting the SOFT-START Time Operation Timing Diagram AC Adaptor Voltage DetectionProcessing Without Using the Current AMP Connection when Current Amp is not usedProcessing Without Using of the Error AMP Connection when Error Amp is not usedProcessing Without Using of the CS Terminal Connection when soft-start time is not specifiedApplication Example At 4 cellParts List Parts NoReference Data Batt Vbatt mV Ta = +25 C, VIN = 19 Batt = 12 Ω Part number Package Remarks Usage PrecautionsOrdering Information Package Dimension IndexFujitsu Limited