Power Supply User Manual

ManualsBrandsFujitsu ManualsPower SupplyMB3878

DS04-27706-2E

FUJITSU SEMICONDUCTOR

DATA SHEET

ASSP

For Power Supply Applications (Secondary battery)

DC/DC Converter IC for Charging

MB3878

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DESCRIPTION

The MB3878 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

adaptor in order to keep its power constant (dynamically-controlled charging).

The charging method enables quick charging, for example, with the AC adaptor during operation of a notebook PC

The MB3878 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.

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FEATURES

• Detecting a voltage drop in the AC adaptor and dynamically controlling the charge current

(Dynamically-controlled charging)

• Output voltage setting using external resistor : 1 cell to 4 cells

• High efficiency : 94 %

• Wide range of operating supply voltages : 7 V to 25 V

• Output voltage setting accuracy : 4.2V ± 0.8% (per cell)

• Built-in frequency setting capacitor enables frequency setting using external resistor only

• Oscillator frequency range : 100kHz to 500kHz

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PACKAGE

24-pin plastic SSOP

(FPT-24P-M03)

Summary of content (24 pages)

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FUJITSU SEMICONDUCTOR DATA SHEET DS04-27706-2E ASSP For Power Supply Applications (Secondary battery) DC/DC Converter IC for Charging MB3878 ■ DESCRIPTION The MB3878 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.
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MB3878 (Continued) • Built-in current detector amplifier with wide in-phase input voltage range : 0 V to Vcc • In standby mode, leave output voltage setting resistor open to prevent inefficient current loss • Built-in standby current function : 0 µA (standard) • Built-in soft-start function • Built-in totem-pole output stage supporting P-channel MOS FETs devices ■ PIN ASSIGNMENT (TOP VIEW) 24 : +INC2 −INC2 : 1 23 : GND OUTC2 : 2 +INE2 : 3 22 : CS −INE2 : 4 21 : VCC (O) 20 : OUT FB2 : 5 19 : VH V
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MB3878 ■ 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 Error amplifier (Error Amp. 2) output pin. 6 VREF O Reference voltage output pin. 7 FB1 O Error amplifier (Error Amp. 1) output pin.
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MB3878 ■ BLOCK DIAGRAM −INE1 8 OUTC1 10 + × 25 − −INC1 12 +INC1 13 VREF − + 21 VCC (O) +INE1 9 + + + Drive − FB1 7 −INE2 4 OUTC2 2 +INC2 24 −INC2 1 + × 25 − +INE2 3 VREF − 20 OUT VCC 19 VH (VCC − 5 V) Bias Voltage + FB2 5 2.5 V 1.5 V VREF (VCC UVLO) 215 kΩ + − + + −INE3 16 OUTD 11 − 4.2 V FB3 15 VCC 35 kΩ 0.91 V (0.
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MB3878 ■ ABSOLUTE MAXIMUM RAGINGS Parameter Symbol Conditions Rating Unit Min Max  28 V  60 mA Power supply voltage VCC Output current IOUT Peak output current IOUT Duty ≤ 5 % (t = 1 / fOSC × Duty)  500 mA Power dissipation PD Ta ≤ +25 °C  740* mW −55 +125 °C Storage temperature VCC, VCC (O)   Tstg * : The package is mounted on the dual-sided epoxy board (10 cm × 10 cm).
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MB3878 ■ ELECTRICAL CHARACTERISTICS Parameter Reference voltage block (Ref) (Ta = +25 °C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA) Value Pin Symbol Conditions Unit No. Min Typ Max Ta = +25 °C 4.995 5.000 5.045 V Ta = −30 °C to +85 °C 4.945 5.000 5.055 V VCC = 7 V to 25 V  3 10 mV 6 VREF = 0 mA to −1 mA  1 10 mV Ios 6 VREF = 1 V −25 −15 −5 mA VTLH 18 VCC = VCC (O) , VCC = 6.1 6.4 6.7 V VTHL 18 VCC = VCC (O) , VCC = 5.1 5.4 5.7 V VH 18 VCC = VCC (O) 0.7 1.
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MB3878 Parameter 16 VTH2 16 Input current IINE3 16 FB3 = 2 V, Ta = −30 °C to +85 °C −INE3 = 0 V Voltage gain AV 15 Frequency bandwidth BW 15 VFBH 15 VFBL 15 ISOURCE 15 ISINK Output voltage Output source current Output sink current OUTD pin output leak current OUTD pin output ON resistor 4.167 4.200 4.233 V 4.158 4.200 4.242 V −100 −30  nA DC  100*  dB AV = 0 dB  2.0*  MHz  4.7 4.9  V   20 200 mV FB3 = 2 V  −2.0 −0.
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MB3878 (Continued) Parameter Output voltage Current detection amplifier block Output source (Current Amp.1, current Current Amp.2) Output sink current PWM comparator block Threshold voltage (PWM Comp.) 4.9  V VOUTCL 2, 10   20 200 mV ISOURCE 2, 10 OUTC1 = OUTC2 = 2 V  −2.0 −0.6 mA ISINK 2, 10 OUTC1 = OUTC2 = 2 V 150 300  µA VTL 5, 7, Duty cycle = 0 % 15 1.4 1.5  V VTH 5, 7, Duty cycle = 100 % 15  2.5 2.
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MB3878 ■ TYPICAL CHARACTERISTICS Power supply current vs. power supply voltage Reference voltage vs. power supply voltage 10 Ta = +25 °C CTL = 5 V 10 Reference voltage VREF (V) Power supply current ICC (mA) 12 8 6 4 2 0 0 5 10 15 20 Ta = +25 °C CTL = 5 V VREF = 0 mA 8 6 4 2 0 25 0 5 Power supply voltage VCC (V) Reference voltage vs. VREF load current 2.0 Ta = +25 °C VCC = 19 V CTL = 5 V 8 6 4 2 5 10 15 20 25 0.5 0.0 −0.5 −1.0 −1.
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Triangular wave oscillator frequency vs. timing resistor 1M Ta = +25 °C VCC = 19 V CTL = 5 V 100 k 10 k 10 k 100 k 1M Triangular wave oscillator frequency fOSC (kHz) Triangular wave oscillator frequency fOSC (Hz) MB3878 Triangular wave oscillator frequency vs.
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MB3878 (Continued) Error amplifier gain and phase vs. frequency 40 Ta = +25 °C AV 180 VCC = 19 V φ 20 90 0 0 240 kΩ Phase φ (deg) Gain AV (dB) 5.2 V −20 −90 −40 −180 1k 10 k 100 k 1M IN 1 µF − + 10 kΩ 2.4 kΩ 10 kΩ 8 (4) − OUT 7 (5) 9 + (3) 2.5 V Error Amp.1 (Error Amp.2) 10 M Frequency f (Hz) Current detection amplifier gain and phase vs. frequency 180 90 AV 0 0 −20 −90 VCC = 19 V Phase φ (deg) 20 Gain AV (dB) Ta = +25 °C φ 40 12.
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MB3878 ■ 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 temperature-compensated, stable voltage (5.0V Typ) used as the reference supply voltage for the IC’s internal circuitry. This pin can also be used to obtain a load current to a maximum of 1mA from the reference voltage VREF terminal (pin 6).
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MB3878 (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 Amp. 1 to Error Amp. 3) depending on their output voltage.
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MB3878 ■ SETTING THE CHARGING VOLTAGE The charging voltage (DC/DC output voltage) can be set by connecting external voltage setting resistors (R3, R4) to the -INE3 terminal. Be sure to select a resistor value that allows you to ignore the on resistor (70 Ω, 1mA) of the internal FET connected to the OUTD terminal (pin 11). Battery charging voltage: VO VO (V) = (R3 + R4) / R4 × 4.2 (V) B VO R3 < Error Amp.3 > −INE3 16 R4 11 OUTD − + + 4.
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MB3878 ■ 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 adaptor power constant when the partial potential point A of the AC adaptor voltage (Vcc) becomes lower than the voltage at the -INE2 terminal. AC adaptor detected voltage setting: Vth Vth (V) = (R1 + R2) / R2 × −INE2 −INE2 setting voltage range : 1.176 V to 4.2 V (equivalent to 7 V to 25 V for Vcc)
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MB3878 ■ PROCESSING WITHOUT USE OF THE CS PIN If the soft-start function is not used, the CS terminal (pin 22) should be left open. Open CS 22 When no soft-start time is 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. • When selecting the reverse current prevention diode, be sure to consider the reverse voltage (VR) and reverse current (IR) of the diode.
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SW R16 R15 200 kΩ 110 Ω Q2 R14 1.3 kΩ R6 68 kΩ R5 330 kΩ R4 82 kΩ 8 FB2 5 CS 2200 pF 15 CS 22 FB3 R18 200 kΩ −INE3 16 R17 C6 100 kΩ 1500 pF 11 R3 OUTD 330 kΩ R7 22 kΩ +INE2 3 VREF 1 µA C8 4 10000 pF OUTC2 R10 2 30 kΩ +INC2 24 + R11 × 25 30 kΩ −INC2 1 − −INE2 OUTC1 10 C10 5600 pF +INC1 + A 13 R9 × 25 10 kΩ − B −INC1 12 R12 30 kΩ +INE1 9 R13 FB1 30 kΩ 7 R8 100 kΩ −INE1 4.2 V RT RT 47 kΩ (45 pF) VCC 2.5 V 1.
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MB3878 ■ PARTS LIST (for APPLICATION EXAMPLE 1) COMPONENT ITEM SPECIFICATION VENDOR PARTS No. Q1 Q2 FET FET Si4435DY 2N7002 VISHAY SILICONIX VISHAY SILICONIX Si4435DY 2N7002 D1 Diode MBRS130LT3 MOTOROLA MBRS130LT3 L1 Coil 12 µH 4.0 A, 38 mΩ SUMIDA CDRH124-12 µH C1 C2, C3 CS C5 C6 C7 C8 C9 C10 OS Condenser OS Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser 22 µF 100 µF 2200 pF 0.
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MB3878 ■ REFERENCE DATA Conversion efficiency vs. charge current (Fixed voltage mode) VIN = 19 V BATT charge voltage = 12.6 V fOSC = 277.9 kHz η (%) = (VBATT × IBATT) / (VIN × IIN) × 100 98 96 94 92 90 88 86 84 82 80 10 m 100 m 1 10 100 Conversion efficiency η (%) Conversion efficiency η (%) 100 Conversion efficiency vs.
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R21 100 kΩ R22 100 kΩ − − R20 100 kΩ VIN + A(2/2) Q2 R19 100 kΩ + A(1/2) VIN SW R16 200 kΩ R15 110 Ω CS 2200 pF C6 1500 pF R3 330 kΩ R18 200 kΩ D R7 22 kΩ R10 24 kΩ R11 36 kΩ C R23 100 kΩ B A C8 10000 pF R13 30 kΩ C10 5600 pF R9 10 kΩ R14 R12 1.3 kΩ 30 kΩ 8 15 CS 22 FB3 −INE3 16 R17 100 kΩ 11 OUTD FB2 5 +INC2 24 VREF 1 µA + × 25 −INC2 1 − +INE2 3 4 7 9 13 OUTC2 2 −INE2 FB1 +INE1 +INC1
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MB3878 ■ PARTS LIST (for APPLICATION EXAMPLE 2) COMPONENT ITEM SPECIFICATION VENDOR PARTS No. Q1 Q2 FET FET Si4435DY 2N7002 VISHAY SILICONIX VISHAY SILICONIX Si4435DY 2N7002 D1 Diode MBRS130LT3 MOTOROLA MBRS130LT3 A Dual Op-amp MB47358 Our Company MB47358 L1 Coil 12 µH 4.
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MB3878 ■ 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.
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MB3878 ■ PACKAGE 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. 0.17±0.03 (.007±.001) * 7.75±0.10(.305±.004) 24 13 5.60±0.10 7.60±0.20 (.220±.004) (.299±.008) INDEX Details of "A" part +0.20 1.25 –0.10 +.008 .049 –.004 (Mounting height) 0.25(.010) 1 "A" 12 0~8° +0.08 0.65(.026) 0.24 –0.07 +.003 .009 –.003 0.13(.005) M 0.50±0.20 (.020±.008) 0.60±0.15 (.024±.006) 0.
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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 incorporated in devices for actual use.