MB3878

Manufacturer Part NumberMB3878
DescriptionDC/DC Converter IC for Charging
ManufacturerFujitsu Media Devices
MB3878 datasheet
 
1
Page 1
2
Page 2
3
Page 3
4
Page 4
5
Page 5
6
Page 6
7
Page 7
8
Page 8
9
Page 9
10
Page 10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Page 1/24

Download datasheet (284Kb)Embed
Next
FUJITSU SEMICONDUCTOR
DATA SHEET
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.
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.
FEATURES
• Detecting a voltage drop in the AC adaptor and dynamically controlling the charge current
(Dynamically-controlled charging)
• Output voltage setting using external resistor
• High efficiency
• Wide range of operating supply voltages
• Output voltage setting accuracy
• Built-in frequency setting capacitor enables frequency setting using external resistor only
• Oscillator frequency range
• 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
• Built-in soft start function
• Built-in totem-pole output stage supporting P-channel MOS FETs devices
PACKAGE
: 1 cell to 4 cells
: 94
: 7 V to 25 V
: 4.2V
0.8% (per cell)
: 100kHz to 500kHz
: 0 A (standard)
24-pin plastic SSOP
(FPT-24P-M03)
DS04-27706-1E

MB3878 Summary of contents

  • Page 1

    ... 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. ...

  • Page 2

    ... MB3878 PIN ASSIGNMENT INC2 : 1 OUTC2 : 2 INE2 : 3 INE2 : 4 FB2 : 5 VREF : 6 FB1 : 7 INE1 : 8 INE1 : 9 OUTC1 : 10 OUTD : 11 INC1 : 12 2 (TOP VIEW INC2 23 : GND VCC ( OUT VCC INE3 15 : FB3 14 : CTL 13 : INC1 (FPT-24P-M03) ...

  • Page 3

    ... Power supply pin for reference power supply and control circuit. Power supply pin for FET drive circuit (VH = Vcc High-side FET gate drive pin. Output circuit power supply pin. Soft-start capacitor connection pin. Ground pin. Current detection amplifier (Current Amp. 2) input pin. MB3878 5 V). 3 ...

  • Page 4

    ... MB3878 BLOCK DIAGRAM 8 INE1 10 OUTC1 <Current Amp.1> 13 INC1 25 12 INC1 9 INE1 7 FB1 INE2 4 2 OUTC2 <Current Amp.2> 24 INC2 25 INC2 1 INE2 3 5 FB2 16 INE3 11 OUTD FB3 15 <SOFT> VREF <Error VREF Amp.1> <PWM Comp.> <OUT> Drive <Error VCC Amp.2> VREF Bias Voltage < ...

  • Page 5

    ... INE1 to INE3, INE1, INE2 INE INC1, INC2, INC1, INC2 INC OUTD OUTD CTL I OUT I Duty fosc Duty) OUT f OSC REF Ta MB3878 Rating Unit Min. Max 500 mA 740 125 C Value Unit Min. Typ. Max ...

  • Page 6

    ... MB3878 ELECTRICAL CHARACTERISTICS Parameter Output voltage Reference Input stability voltage block Load stability (Ref) Short-circuit output current Threshold voltage Under voltage lockout protection Hysteresis width circuit block (UVLO) Threshold voltage Hysteresis width Soft-start block Charge current (SOFT) Oscillation Triangular frequency waveform ...

  • Page 7

    ... INC2 0. OUTC4 INC1 INC2 12 13 INC1 INC2 12 INC1 INC2 12 MB3878 19 V, VREF 0 mA) Value Unit Min. Typ. Max. 4.167 4.200 4.233 V 4.158 4.200 4.242 V 100 30 nA 100* dB 2.0* MHz 4.7 4 200 mV 2.0 0.6 ...

  • Page 8

    ... 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.) Output source current Output sink current Output block Output ON (OUT) resistor Rise time Fall time ...

  • Page 9

    ... Ambient temperature CTL pin current vs. CTL pin voltage 1 VCC 19 V VREF 0 mA 0.8 0.6 0.4 0.2 0 2.5 (V) CTL pin voltage V MB3878 CTL 5 V VREF (V) CC VCC 19 V CTL 5 V VREF 100 VCC ...

  • Page 10

    ... MB3878 Triangular wave oscillator frequency vs. timing resistor 1 M 100 100 k Timing resistor R Triangular wave oscillator frequency 340 330 320 310 300 290 280 270 260 250 240 Ambient temperature Triangular wave oscillator frequency vs. 340 330 ...

  • Page 11

    ... 2 180 180 12.6 V 180 100 MB3878 VCC 19 V 240 k 8 OUT (4) 7 (5) 9 (3) Error Amp.1 2.5 V (Error Amp.2) VCC OUT (24 (2) 12 (1) Current Amp.1 12.55 V (Current Amp.2) 11 ...

  • Page 12

    ... 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 tem- perature-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) ...

  • Page 13

    ... Connecting a capacitor to the CS terminal (pin 22) prevents surge currents when the IC is turned on. Using an error amplifier for soft start detection makes the soft start time constant, independent of the output load of the DC/DC converter (typ.) as the minimum potential of the output circuit. In the standby MB3878 13 ...

  • Page 14

    ... 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 , 1mA) of the internal FET connected to the OUTD terminal (pin 11). ...

  • Page 15

    ... INE2 setting voltage range : 1.176 V to 4.2 V (equivalent for Vcc) INE2 INE2 R2 OPERATION TIMING DIAGRAM Error Amp.1 FB1 Error Amp.3 FB3 Error Amp.2 FB2 OUT AC adaptor dynamically- Constant controlled charging voltage control <Error Amp.2> Constant current control MB3878 2 adaptor dynamically- controlled charging 15 ...

  • Page 16

    ... 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. 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 (V current ( the diode ...

  • Page 17

    ... APPLICATION EXAMPLE 1 MB3878 17 ...

  • Page 18

    ... MB3878 PARTS LIST (for APPLICATION EXAMPLE 1) COMPONENT ITEM Q1 FET Q2 FET D1 Diode L1 Coil C1 OS Condenser C2 Condenser C Ceramics Condenser S C5 Ceramics Condenser C6 Ceramics Condenser C7 Ceramics Condenser C8 Ceramics Condenser C9 Ceramics Condenser C10 Ceramics Condenser R Resistor S R Resistor T R3 Resistor R4 Resistor R5 Resistor R6 Resistor R7 Resistor ...

  • Page 19

    ... BATT DC/DC converter switching waveforms OUTH ( FB3 ( 160 200 t (ms) MB3878 VIN 19 V BATT : Electronic load, (Product of KIKUSUI PLZ-150W (V) BATT VIN 277.9 kHz OSC Load : BATT ...

  • Page 20

    ... MB3878 APPLICATION EXAMPLE 2 20 ...

  • Page 21

    ... V (10 ) 100 (10 ) 2200 1500 10000 5600 pF 10 0.033 1 1.0 330 k 1 1.0 100 0.5 1.3 k 0.5 110 0.5 200 k 5 100 k 1.0 200 k 0.5 100 k 1.0 100 k 0.5 100 k 1.0 MB3878 PARTS No. Si4435DY 2N7002 MBRS130LT3 MB47358 CDRH124- ...

  • Page 22

    ... Working personnel should be grounded with resistance of 250 between body and ground. • Do not apply negative voltages. The use of negative voltages below –0.3 V may create parasitic transistors on LSI lines, which can cause abnormal operation ORDERING INFORMATION Part number MB3878PFV 22 Package 24-pin plastic SSOP (FPT-24P-M03) Remarks ...

  • Page 23

    ... NOM "A" +0.10 +0.05 0.22 0.15 –0.05 –0.02 +.004 +.002 .009 .006 –.002 –.001 MB3878 Details of "A" part 0.10±0.10(.004±.004) (STAND OFF) 0 10° 0.50±0.20 (.020±.008) Dimensions in mm (inches). 23 ...

  • Page 24

    ... MB3878 FUJITSU LIMITED For further information please contact: Japan FUJITSU LIMITED Corporate Global Business Support Division Electronic Devices KAWASAKI PLANT, 4-1-1, Kamikodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa 211-8588, Japan Tel: +81-44-754-3763 Fax: +81-44-754-3329 http://www.fujitsu.co.jp/ North and South America FUJITSU MICROELECTRONICS, INC. 3545 North First Street, San Jose, CA 95134-1804, U ...