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Fujitsu MB3887 Datasheet

Dc/dc converter ic for charging li-ion battery.
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FUJITSU SEMICONDUCTOR
DATA SHEET
ASSP For Power Supply Applications (Secondary battery)
DC/DC Converter IC
for Charging Li-ion battery
MB3887
DESCRIPTION
The MB3887 is a DC/DC converter IC suitable for down-conversion, using pulse-width (PWM) charging and
enabling output voltage to be set to any desired level from one cell to four cells.
These ICs can dynamically control the secondary battery's charge current by detecting a voltage drop in an AC
adapter in order to keep its power constant (dynamically-controlled charging) .
The charging method enables quick charging, for example, with the AC adapter during operation of a notebook PC.
The MB3887 provides a broad power supply voltage range and low standby current as well as high efficiency,
making it ideal for use as a built-in charging device in products such as notebook PC.
This product is covered by US Patent Number 6,147,477.
FEATURES
• Detecting a voltage drop in the AC adapter and dynamically controlling the charge current
(Dynamically-controlled charging)
PACKAGE
24-pin plastic SSOP
(FPT-24P-M03)
DS04-27709-3E
(Continued)

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   Summary of Contents for Fujitsu MB3887

  • Page 1

    FUJITSU SEMICONDUCTOR DS04-27709-3E DATA SHEET ASSP For Power Supply Applications (Secondary battery) DC/DC Converter IC for Charging Li-ion battery MB3887 DESCRIPTION The MB3887 is a DC/DC converter IC suitable for down-conversion, using pulse-width (PWM) charging and enabling output voltage to be set to any desired level from one cell to four cells.

  • Page 2

    MB3887 (Continued) • Output voltage setting using external resistor : 1 cell to 4 cells • High efficiency : 96 (VIN 19 V, Vo 16.8 V) • Wide range of operating supply voltages : 8 V to 25 V • Output voltage setting accuracy : 4.2 V 0.74 (Ta 10 C to 85 C , per cell) •...

  • Page 3: Table Of Contents

    MB3887 PIN ASSIGNMENT (TOP VIEW) INC2 : : INC2 OUTC2 : : GND INE2 : : CS INE2 : : VCC (O) FB2 : : OUT VREF : : VH FB1 : : VCC INE1 : : RT INE1 : : INE3 OUTC1 : : FB3...

  • Page 4: Outc2

    MB3887 PIN DESCRIPTION Pin No. Symbol Descriptions INC2 Current detection amplifier (Current Amp2) input terminal. OUTC2 Current detection amplifier (Current Amp2) output terminal. INE2 Error amplifier (Error Amp2) non-inverted input terminal. INE2 Error amplifier (Error Amp2) inverted input terminal. Error amplifier (Error Amp2) output terminal. VREF Reference voltage output terminal.

  • Page 5: Ine2

    MB3887 BLOCK DIAGRAM INE1 OUTC1 <Error Amp1> <Current Amp1> VREF INC1 INC1 VCC (O) INE1 <PWM Comp.> <OUT> Drive INE2 <Error Amp2> OUTC2 <Current Amp2> VREF INC2 Bias INC2 Voltage 6 V) <VH> INE2 2.5 V 1.5 V <UVLO> <Error Amp3> VREF (VCC UVLO) 215 k...

  • Page 6

    MB3887 ABSOLUTE MAXIMUM RATINGS Rating Parameter Symbol Conditions Unit Power supply voltage VCC, VCC (O) terminal Output current Duty Peak output current Duty) Power dissipation 25 C 740* Storage temperature * : The package is mounted on the dual-sided epoxy board (10 cm 10 cm) .

  • Page 7: Inc2

    No warranty is made with respect to uses, operating conditions, or combinations not represented on the data sheet. Users considering application outside the listed conditions are advised to contact their FUJITSU representatives beforehand.

  • Page 8

    MB3887 ELECTRICAL CHARACTERISTICS 25 C, VCC 19 V, VCC (O) 19 V, VREF 0 mA) Value Sym- Parameter Conditions Unit 25 C 4.967 5.000 5.041 REF1 Output voltage 10 C to 85 C 4.95 5.00 5.05 REF2 Reference Input stability Line 8 V to 25 V voltage block...

  • Page 9: Outd

    MB3887 25 C, VCC 19 V, VCC (O) 19 V, VREF 0 mA) Value Sym- Parameter Conditions Unit 2 V, Ta 25 C 4.183 4.200 4.225 Threshold voltage 2 V, 4.169 4.200 4.231 10 C to 85 C Input current INE3 INE3 Voltage gain...

  • Page 10: Ine2

    MB3887 25 C, VCC 19 V, VCC (O) 19 V, VREF 0 mA) Value Sym- Parameter Conditions Unit INC1 INC2 2, 10 3 V to VCC, OUTC1 100 mV INC1 INC2 2, 10 3 V to VCC, 0.34 0.40 0.46 OUTC2 20 mV Current detection...

  • Page 11

    MB3887 (Continued) 25 C, VCC 19 V, VCC (O) 19 V, VREF 0 mA) Value Sym- Parameter Conditions Unit Output source OUT 13 V, Duty 5 400* SOURCE current Duty) Output sink OUT 19 V, Duty 5 400* SINK current Duty) 45 mA Output ON...

  • Page 12: Vref

    MB3887 TYPICAL CHARACTERISTICS Power supply current vs. Power supply voltage Reference voltage vs. Power supply voltage CTL 5 V CTL 5 V VREF 0 mA Power supply voltage V Power supply voltage V Reference voltage vs. I load current Reference voltage vs. Ambient temperature 5.08 VCC 19 V VCC 19 V...

  • Page 13

    MB3887 Triangular wave oscillation frequency Triangular wave oscillation frequency vs. Timing resistor vs. Power supply voltage VCC 19 V CTL 5 V CTL 5 V RT 47 k 100 k 10 k 1000 Timing resistor R (k ) Power supply voltage V Triangular wave oscillation frequency Error amplifier threshold voltage vs.

  • Page 14: Ine1

    MB3887 Error amplifier gain and phase vs. Frequency VCC 19 V 4.2 V 240 k 10 k 10 k 2.4 k Error Amp1 10 k 10 k (Error Amp2) 10 k 100 k 10 M Frequency f (Hz) Error amplifier gain and phase vs. Frequency VCC 19 V 4.2 V 240 k...

  • Page 15: Ine1

    MB3887 (Continued) Power dissipation vs. Ambient temperature Ambient temperature Ta ( C)

  • Page 16

    MB3887 FUNCTIONAL DESCRIPTION 1. DC/DC Converter Unit (1) Reference voltage block (Ref) The reference voltage generator uses the voltage supplied from the VCC terminal (pin 18) to generate a tem- perature-compensated, stable voltage (5.0 V Typ) used as the reference supply voltage for the IC’s internal circuitry.

  • Page 17: Outd

    MB3887 (7) PWM comparator block (PWM Comp.) The PWM comparator circuit is a voltage-pulse width converter for controlling the output duty of the error amplifiers (Error Amp1 to Error Amp3) depending on their output voltage. The PWM comparator circuit compares the triangular wave generated by the triangular wave oscillator to the error amplifier output voltage and turns on the external output transistor during the interval in which the triangular wave voltage is lower than the error amplifier output voltage.

  • Page 18

    MB3887 3. Soft-Start Function Soft-start block (SOFT) Connecting a capacitor to the CS terminal (pin 22) prevents rush currents when the IC is turned on. Using an error amplifier for soft-start detection makes the soft-start time constant, being independent of the output load of the DC/DC converter.

  • Page 19: Inc1

    MB3887 METHOD OF SETTING THE SOFT-START TIME For preventing rush current upon activation of IC, the IC allows soft-start using the capacitor (Cs) connected to the CS terminal (pin 22) . When CTL terminal (pin 14) is placed under “H” level and IC is activated (V UVLO threshold voltage) , Q2 is turned off and the external soft-start capacitor (Cs) connected to the CS terminal is charged at 10 A.

  • Page 20

    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.

  • Page 21

    MB3887 PROCESSING WITHOUT USING THE CURRENT AMP When Current Amp is not used, connect the INC1 terminal (pin 13) , INC2 terminal (pin 24) , INC1 terminal (pin 12) , and INC2 terminal (pin 1) to VREF, and then leave OUTC1 terminal (pin 10) and OUTC2 terminal (pin 2) open.

  • Page 22: Ine3

    MB3887 PROCESSING WITHOUT USING OF THE ERROR AMP When Error Amp is not used, leave FB1 terminal (pin 7) , FB2 terminal (pin 5) open and connect the INE1 terminal (pin 8) and INE2 terminal (pin 4) to GND and connect INE1 terminal (pin 9) , and INE2 terminal (pin 3) , to VREF.

  • Page 23

    MB3887 PROCESSING WITHOUT USING OF THE CS TERMINAL When soft-start function is not used, leave the CS terminal (pin 22) open. “Open” Connection when soft-start time is not specified NOTE ON AN EXTERNAL REVERSE-CURRENT PREVENTIVE DIODE • Insert a reverse-current preventive diode at one of the three locations marked * to prevent reverse current from the battery.

  • Page 24

    MB3887 APPLICATION EXAMPLE...

  • Page 25: Inc1

    MB3887 PARTS LIST COMPONENT ITEM SPECIFICATION VENDOR PARTS No. 30 V, ID 8 A (Max) P-ch FET VISHAY SILICONIX Si4435DY 60 V, ID 0.115 A N-ch FET VISHAY SILICONIX 2N7002E (Max) Diode 0.42 V (Max) , IF ROHM RB053L-30 3.5 A, 31.6 SLF12565T- Inductor 22 H...

  • Page 26

    MB3887 REFERENCE DATA Conversion efficiency vs. Charge current Conversion efficiency vs. Charge current (Constant voltage mode) (Constant current mode) 19 V VIN 19 V BATT charge voltage BATT charge voltage set at 12.6 V set at 12.6 V SW ON Efficiency Efficiency BATT...

  • Page 27

    MB3887 Conversion efficiency vs. Charge current Conversion efficiency vs. Charge current (Constant current mode) (Constant voltage mode) VIN 19 V VIN 19 V BATT charge voltage BATT charge voltage set at 16.8 V set at 16.8 V SW ON SW ON Efficiency Efficiency BATT...

  • Page 28

    MB3887 Switching waveform constant voltage mode Switching waveform constant current mode (set at 12.6 V) (set at 12.6 V, with 10 V) (mV) BATT (mV) BATT VIN 19 V VIN 19 V 98 mVp-p 98 mVp-p BATT BATT 1.5 A BATT BATT 3.0 A ( s)

  • Page 29

    MB3887 (Continued) Soft-start operating waveform Discharge operating waveform constant voltage mode constant voltage mode (set at 12.6 V) (set at 12.6 V) BATT BATT BATT 19 V BATT BATT 10.4 ms 19 V BATT 10 12 14 16 18 20 10 12 14 16 18 20 (ms) (ms)

  • Page 30: Inc2

    MB3887 USAGE PRECAUTIONS • Printed circuit board ground lines should be set up with consideration for common impedance. • Take appropriate static electricity measures. Containers for semiconductor materials should have anti-static protection or be made of conductive material. After mounting, printed circuit boards should be stored and shipped in conductive bags or containers. Work platforms, tools, and instruments should be properly grounded.

  • Page 31: Package Dimension

    Details of "A" part +0.20 1.25 –0.10 (Mounting height) +.008 .049 –.004 0.25(.010) 0~8° "A" +0.08 0.65(.026) 0.24 –0.07 0.13(.005) +.003 .009 0.50±0.20 0.10±0.10 –.003 (.020±.008) (.004±.004) (Stand off) 0.60±0.15 (.024±.006) 0.10(.004) 0.10(.004) 2001 FUJITSU LIMITED F24018S-c-3-4 Dimensions in mm (inches) .

  • Page 32

    (2) for use requiring extremely high reliability (i.e., submersible repeater and artificial satellite). Please note that Fujitsu will not be liable against you and/or any third party for any claims or damages arising in connection with above-mentioned uses of the products.

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