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Fujitsu MB3878 - page 1
DS04-27706-2E FUJITSU SEMICONDUCT OR DA T A S H E E T ASSP F or P o wer Supply Applications (Secondar y batter y) DC/DC Con ver ter IC f or Char ging MB3878 ■ ■ ■ ■ DESCRIPTION The MB3878 is a DC/DC conv er ter IC suitab le f or down-con v ersion, using pulse-width (PWM) charging and enabling output v oltage to be set to any desired le vel ...
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Fujitsu MB3878 - page 2
MB3878 2 (Continued) • Built-in current detector amplifier with wide in-phase input v oltage range : 0 V to Vcc • In standb y mode, leav e output voltage setting resistor open to pre vent inefficient current loss • Built-in standb y current function : 0 µ A (standard) • Built-in soft-star t function • Built-in totem-pole output stage sup ...
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Fujitsu MB3878 - page 3
MB3878 3 ■ ■ ■ ■ PIN DESCRIPTION Pin No. Symbol I/O Descriptions 1 − INC2 I Current detection amplifier (Current Amp. 2) input pin. 2 OUTC2 O Current detection amplifier (Current Amp. 2) output pin. 3 + INE2 I Error amplifier (Error Amp. 2) non-inverted input pin. 4 − INE2 I Error amplifier (Error Amp. 2) inverted input pin. 5 FB2 O Err ...
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Fujitsu MB3878 - page 4
MB3878 4 ■ ■ ■ ■ BLOCK DIA GRAM + − − + 8 10 13 12 9 + − − + 4 2 24 1 3 × 25 × 25 + + + − 5 20 21 19 − + + + − 11 16 22 17 6 23 14 18 <Current Amp.1> <Error Amp.1> 7 VREF <Current Amp.2> <Error Amp.2> VREF <Error Amp.3> VREF VREF VREF 5.0 V 4.2 V 1 µ A 15 <SOFT> 2.5 V 1.5 V <OUT> &l ...
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Fujitsu MB3878 - page 5
MB3878 5 ■ ■ ■ ■ ABSOLUTE MAXIMUM RA GINGS * : The package is mounted on the dual-sided epo xy board (10 cm × 10 cm). W ARNING: Semiconductor de vices can be per manently damaged by application of stress (v oltage, current, temperature , etc.) in e xcess of absolute maximum ratings. Do not e xceed these ratings. ■ ■ ■ ■ RECOMMENDED ...
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Fujitsu MB3878 - page 6
MB3878 6 ■ ■ ■ ■ ELECTRICAL CHARA CTERISTICS (Ta = + 25 ° C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA) * : Standard design v alue. (Continued) Parameter Symbol Pin No. Conditions Value Unit Min Typ Max Reference voltage block (Ref) Output voltage V REF 6 Ta = + 25 ° C 4.995 5.000 5.045 V Ta = − 30 ° C to + 85 ° C 4.945 5.000 5.055 V In ...
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Fujitsu MB3878 - page 7
MB3878 7 (Ta = + 25 ° C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA) * : Standard design v alue. (Continued) Parameter Symbol Pin No. Conditions Value Unit Min Typ Max Error amplifier block (Error Amp.3) Threshold voltage V TH1 16 FB3 = 2 V, Ta = + 25 ° C 4.167 4.200 4.233 V V TH2 16 FB3 = 2 V, Ta = − 30 ° C to + 85 ° C 4.158 4.200 4.242 V Input ...
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Fujitsu MB3878 - page 8
MB3878 8 (Continued) (Ta = + 25 ° C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA) * : Standard design v alue Parameter Symbol Pin No. Conditions Value Unit Min Typ Max Current detection amplifier block (Current Amp.1, Current Amp.2) Output voltage V OUTCH 2, 10 4.7 4.9 V V OUTCL 2, 10 20 200 mV Output source current I SOURCE 2, 10 OUTC1 ...
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Fujitsu MB3878 - page 9
MB3878 9 ■ ■ ■ ■ TYPICAL CHARA CTERISTICS (Continued) Ta = + 25 ° C CTL = 5 V 12 10 8 6 4 2 0 0 5 10 15 20 25 Ta = + 25 ° C CTL = 5 V VREF = 0 mA 10 8 6 4 2 0 0 5 10 15 20 25 Ta = + 25 ° C VCC = 19 V CTL = 5 V 10 8 6 4 2 0 0 5 10 15 20 25 30 2.0 1.5 1.0 0.5 0.0 − 0.5 − 1.0 − 1.5 − 2.0 − 40 − 20 0 20 40 60 80 100 VCC = 19 V CT ...
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Fujitsu MB3878 - page 10
MB3878 10 (Continued) Ta = + 25 ° C VCC = 19 V CTL = 5 V 1 M 100 k 10 k 10 k 100 k 1 M Ta = + 25 ° C CTL = 5 V RT = 47 k Ω 340 330 320 310 300 290 280 270 260 250 240 0 5 10 15 20 25 VCC = 19 V CTL = 5 V RT = 47 k Ω 340 330 320 310 300 290 280 270 260 250 240 − 40 − 20 0 20 40 60 80 100 VCC = 19 V CTL = 5 V 5.0 4.0 3.0 2.0 1.0 0.0 − 1.0 ...
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Fujitsu MB3878 - page 11
MB3878 11 (Continued) − + −+ VCC = 19 V Error Amp.1 (Error Amp.2) (3) (5) (4) 2.5 V 10 k Ω 2.4 k Ω 240 k Ω 10 k Ω 5.2 V 1 µ F OUT IN φ A V Ta = + 25 ° C 40 20 0 − 20 − 40 180 90 0 − 90 − 180 1 k 10 k 100 k 1 M 10 M 7 8 9 VCC = 19 V Current Amp.1 (Current Amp.2) + − (1) (2) (24) × 25 12.55 V 12.6 V OUT φ Ta = + 25 ° C 40 ...
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Fujitsu MB3878 - page 12
MB3878 12 ■ ■ ■ ■ FUNCTIONAL DESCRIPTION 1. DC/DC Con ver ter Unit (1) Reference v oltage bloc k (Ref) The ref erence voltage generator uses the v oltage supplied from the VCC ter minal (pin 18) to generate a tem- perature-compensated, stab le voltage (5.0V T yp) used as the ref erence supply voltage f or the IC’ s inter nal circuitr y . ...
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Fujitsu MB3878 - page 13
MB3878 13 (7) PWM comparator b lock (PWM Comp.) The PWM comparator circuit is a v oltage-pulse width conv er ter f or controlling the output duty of the error amplifiers (Error Amp . 1 to Error Amp . 3) depending on their output v oltage. The PWM comparator circuit compares the triangular wa ve generated b y the tr iangular w av e oscillator to the ...
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Fujitsu MB3878 - page 14
MB3878 14 ■ ■ ■ ■ SETTING THE CHARGING V OL T A GE The charging v oltage (DC/DC output voltage) can be set b y connecting e xter nal voltage setting resistors (R3, R4) to the -INE3 ter minal. Be sure to select a resistor v alue that allows you to ignore the on resistor (70 Ω , 1mA) of the inter nal FET connected to the OUTD ter minal (pin ...
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Fujitsu MB3878 - page 15
MB3878 15 ■ ■ ■ ■ A C AD APT OR V OL T A GE DETECTION With an e xter nal resistor connected to the +INE2 ter m inal(pin 3), the IC enters the dynamically-controlled charging mode to reduce the charge current to keep A C adaptor po wer constant when the par tial potential point A of the A C adaptor voltage (Vcc) becomes lo wer than the v olt ...
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Fujitsu MB3878 - page 16
MB3878 16 ■ ■ ■ ■ PR OCESSING WITHOUT USE OF THE CS PIN If the soft-star t function is not used, the CS ter minal (pin 22) should be left open. When no soft-start time is specified. ■ ■ ■ ■ NO TE ON AN EXTERNAL REVERSE-CURRENT PREVENTIVE DIODE • Inser t a rev erse-current prev entive diode at one of the three locations mark ed * t ...
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Fujitsu MB3878 - page 17
MB3878 17 ■ ■ ■ ■ APPLICA TION EXAMPLE 1 + − − + 8 10 13 12 A B 9 + − − + 4 2 24 1 3 × 25 × 25 + + + − 5 20 21 19 − + + + − 11 16 22 17 6 23 14 18 <Current Amp.1> <Error Amp.1> 7 VREF <Current Amp.2> <Error Amp.2> VREF <Error Amp.3> VREF VREF VREF 5.0 V 4.2 V 1 µ A 15 <SOFT> 2.5 V 1.5 V & ...
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Fujitsu MB3878 - page 18
MB3878 18 ■ ■ ■ ■ P ARTS LIST (f or APPLICA TION EXAMPLE 1) Note VISHA Y SILICONIX : VISHA Y Inter technolog y, Inc. MO T OROLA : Motorola J apan Ltd. SUMID A : SUMID A ELECTRIC CO ., Ltd. COMPONENT ITEM SPECIFICA TION VENDOR P ARTS No. Q1 Q2 FET FET Si4435DY 2N7002 VISHAY SILICONIX VISHAY SILICONIX Si4435DY 2N7002 D1 Diode MBRS130LT3 MOTOR ...
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Fujitsu MB3878 - page 19
MB3878 19 ■ ■ ■ ■ REFERENCE D A T A 100 98 96 94 92 90 88 86 84 82 80 10 m 100 m 1 10 100 98 96 94 92 90 88 86 84 82 80 0 2 4 6 8 10 12 14 16 18 16 14 12 10 8 6 4 2 0 012345 DCC : Dynamically Controlled Charging Dead Battery MODE DCC MODE 20 15 10 5 0 20 15 10 5 0 0 80 120 160 200 t (ms) 40 BATT (V) CTL (V) 5 V 5 V 20 ms 20 15 10 5 0 4 2 0 ...
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Fujitsu MB3878 - page 20
MB3878 20 ■ ■ ■ ■ APPLICA TION EXAMPLE 2 + − − + 8 10 13 12 A B C D 9 + − + − + − − + 4 2 24 1 3 × 25 × 25 + + + − 5 20 21 19 − + + + − 11 16 22 17 6 23 14 18 <Current Amp.1> <Error Amp.1> 7 VREF <Current Amp.2> <Error Amp.2> VREF <Error Amp.3> VREF VREF VREF 5.0 V 4.2 V 1 µ A 15 <SOFT&g ...
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Fujitsu MB3878 - page 21
MB3878 21 ■ ■ ■ ■ P ARTS LIST (f or APPLICA TION EXAMPLE 2) Note VISHA Y SILICONIX : VISHA Y Inter technolog y, Inc. MO T OROLA : Motorola J apan Ltd. SUMID A : SUMID A ELECTRIC CO ., Ltd. COMPONENT ITEM SPECIFICA TION VENDOR P AR TS No. Q1 Q2 FET FET Si4435DY 2N7002 VISHAY SILICONIX VISHAY SILICONIX Si4435DY 2N7002 D1 Diode MBRS130LT3 MOTO ...
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Fujitsu MB3878 - page 22
MB3878 22 ■ ■ ■ ■ USA GE PRECA UTIONS • Printed cir cuit board gr ound lines should be set up with consideration f or common impedance. • T ake appropriate static electricity measures. • Containers f or semiconductor materials should ha v e anti-static protection or be made of conductive material. • After mounting, printed circuit b ...
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Fujitsu MB3878 - page 23
MB3878 23 ■ ■ ■ ■ P A CKA GE DIMENSION 24-pin plastic SSOP (FPT-24P-M03) Note1: Pins width and pins thickness include plating thickness. Note2: * This dimension does not include resin protrusion. Dimensions in mm (inches) C 2001 FUJITSU LIMITED F24018S-c-3-4 7.75±0.10(.305±.004) 5.60±0.10 7.60±0.20 (.220±.004) (.299±.008) * 0.10(.004) ...
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Fujitsu MB3878 - page 24
MB3878 FUJITSU LIMITED All Rights Reserved. The contents of this document are subject to change without notice. Customers are advised to consult with FUJITSU sales representatives before ordering. The information and circuit diagrams in this document are presented as examples of semiconductor device applications, and are not intended to be incorpor ...
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