MB3886PFV

Manufacturer Part NumberMB3886PFV
Description2-Channel DC/DC Converter IC with Overcurrent Protection Symmetrical-Phase Type
ManufacturerFUJITSU [Fujitsu Component Limited.]
MB3886PFV datasheet
 


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FUJITSU SEMICONDUCTOR
DATA SHEET
ASSP
For Power Supply Applications (General Purpose DC/DC Converter)
2-Channel DC/DC Converter IC
with Overcurrent Protection Symmetrical-Phase Type
MB3886
DESCRIPTION
The MB3886 is a symmetrical-phase type of two-channel, DC/DC converter IC using pulse width modulation
(PWM) , incorporating an overcurrent protection circuit (requiring no current sense resistor) and an overvoltage
protection circuit. Providing high output driving capabilities, the MB3886 is suitable for down-conversion.
The MB3886 adopts both synchronous rectification to provide high efficiency and symmetrical phasing (two anti-
phase triangular waves) which contributes to making the input capacitor small.
The MB3886 contains a 5-volt regulator resulting in a reduced number of components used. It also contains a
variety of protection features which output the protection status upon detection of an overvoltage or overcurrent
while reducing the number of external protective devices required.
The result is an ideal built-in power supply for driving products with high speed CPU’s such as home TV game
devices and notebook PC’s.
This product is covered by US Patent Number 6,147,477.
FEATURES
• Overcurrent protection circuit (requiring no current sense resistor) and overvoltage protection circuit
• Power-supply voltage range : 5.5 V to 18 V
• Synchronous rectification system providing high efficiency
• PSIG pins (open-drain) to output the protection status
PACKAGE
30-pin plastic SSOP
(FPT-30P-M02)
DS04-27228-2E
(Continued)

MB3886PFV Summary of contents

  • Page 1

    FUJITSU SEMICONDUCTOR DATA SHEET ASSP For Power Supply Applications (General Purpose DC/DC Converter) 2-Channel DC/DC Converter IC with Overcurrent Protection Symmetrical-Phase Type MB3886 DESCRIPTION The MB3886 is a symmetrical-phase type of two-channel, DC/DC converter IC using pulse width modulation (PWM) ...

  • Page 2

    MB3886 (Continued) • Symmetrical-phase system reducing the input capacitor loss • Built-in channel control function • Reference voltage : 3 • Error amplifier threshold voltage : 1.25 V • Oscillator frequency range : 10 kHz to 500 kHz ...

  • Page 3

    PIN DESCRIPTION Pin No. Pin name I/O 1 PSIG1 O CH1 protection status output terminal CH1 control terminal 2 CTL1 I “H” level : CH1 ON state “L” level : CH1 OFF state and protection status reset 3 ILIM1 I ...

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    MB3886 BLOCK DIAGRAM 9 FB1 INE1 CS1 7 VREF 10 A 3.8 k INC1 10 2 CTL1 PSIG1 1 FB2 INE2 CS2 24 VREF INC2 29 CTL2 1.47 ...

  • Page 5

    ABSOLUTE MAXIMUM RATINGS Parameter Symbol Power-supply voltage V CC Boot voltage V CB Output current I O Peak output current I OP Power dissipation P D Storage temperature Tstg * : The packages are mounted on the dual-sided epoxy board ...

  • Page 6

    MB3886 RECOMMENDED OPERATING CONDITIONS Parameter Power-supply voltage Boot voltage Reference voltage output current Bias output current Input voltage Output voltage Output current Peak output current Oscillator frequency Timing resistor Timing capacitor Boot capacitor Reference voltage output capacitor Bias output capacitor ...

  • Page 7

    ELECTRICAL CHARACTERISTICS Sym- Parameter bol V Output voltage Reference Voltage Input stability Line Block [Ref] Load stability Load Short-circuit Ios output current 2. Bias Voltage Output voltage V Block [VB] Oscillator f 3. Triangular OSC frequency Waveform ...

  • Page 8

    MB3886 Parameter 10. Soft-start Circuit Block Charge current [CS] Threshold voltage Input bias current Voltage gain 11. Error Amp. Block Frequency [Error Amp.] bandwidth Output voltage Output source current Output sink current 12. PWM Comparator Threshold Block voltage [PWM Comp.] ...

  • Page 9

    Sym- Parameter bol Diode voltage V 14. Output Block [Drive] Dead time Output ON V condition 15. Channel control Block Output OFF V [CTL] condition Input current I Power-supply 16. General I current (VCC Pin Conditions ...

  • Page 10

    MB3886 TYPICAL CHARACTERISTICS Supply Current vs. Supply Voltage Supply voltage V Reference Voltage vs. Ambient Temperature 2 1.5 1 0.5 0 0 ...

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    Triangular Waveform Oscillation Frequency vs. Supply Voltage 320 315 310 305 300 295 290 285 280 275 270 265 260 Supply voltage V Error Amp. Gain/Phase vs. Frequency (CH1 ...

  • Page 12

    MB3886 FUNCTIONAL DESCRIPTION 1. DC/DC Converter Functions (1) Reference voltage Block The reference voltage circuit generates a temperature-compensated reference voltage (typically 3.5 V) using the voltage supplied from the power supply terminal (pin 26) . The voltage is used as ...

  • Page 13

    Channel Control Function Channels are turned on and off depending on the voltage levels at the CTL1 terminal (pin 2) and CTL2 terminal (pin 29). CTL terminal voltage level CTL1 Protective Functions (1) Timer-Latch ...

  • Page 14

    MB3886 SETTING THE OUTPUT VOLTAGE SETTING THE OSCILLATION FREQUENCY The oscillation frequency can be set by connecting the timing capacitor (C resistor ( the RT terminal (pin Oscillation frequency : f ...

  • Page 15

    SETTING THE SOFT-START AND DISCHARGE TIMES To prevent surge currents when the IC is turned on, you can set a soft-start by connecting soft-start capacitors (C and the CS1 terminal (pin 7) for channel 1 and the ...

  • Page 16

    MB3886 (FB2) 22 FB1 ( INE2) 23 INE1 (CS2) 24 CS1 (CTL2) 29 CTL1 TREATMENT OF UNUSED CS PINS When the soft-start function is not used, the CS1 terminal (pin 7) and CS2 terminal (pin ...

  • Page 17

    SETTING THE OVERCURRENT DETECTION CURRENT The overcurrent protection circuit is actuated upon completion of the soft-start period overcurrent flows, the circuit detects the increase in the voltage between the main-side FET’s drain and source by the main-side FET ...

  • Page 18

    MB3886 TREATMENT OF UNUSED PSIG PINS When the PSIG terminals are not used, the PSIG1 terminal (pin 1) and PSIG2 terminal (pin 30) should be shorted or open to the SGND terminal (pin PSIG1 6 SGND < ...

  • Page 19

    SETTING THE TIME CONSTANT FOR TIMER-LATCH SHORT-CIRCUIT PROTECTION CIRCUIT Each channel uses the short-circuit detection comparator (SCP Comp.) to always compare the error amplifier’s output level to the reference voltage. While the DC/DC converter load conditions are stable on both ...

  • Page 20

    MB3886 SETTING THE OVERVOLTAGE DETECTION VOLTAGE An overvoltage output from the DC/DC converter can be detected by connecting external resistors from the DC/ DC converter output voltage to the INC1 terminal (pin 10) and INC2 terminal (pin 21) of the ...

  • Page 21

    OUTPUT STATES DURING PROTECTION CIRCUIT OPERATION The table below lists the output states with individual protection circuits actuated. Output terminal Protection circuit OUT1-1 CH1 L Overcurrent protection circuit CH2 Active CH1 L Overvoltage protection circuit CH2 Active CH1 L Short-circuit ...

  • Page 22

    MB3886 NOTE ON IC’S INTERNAL POWER CONSUMPTION The oscillation frequency and the total gate charge of FETs largely affects the internal dissipation of the IC. Pay attention to the following point with respect to the internal power ...

  • Page 23

    Vin VCC Drive 1-1 Drive 2-1 VOUT1-1 VOUT2 See “Power Consumption vs. Input Voltage” on the next page as a reference and use the above method of obtaining the power consumption to design ...

  • Page 24

    MB3886 Power Consumption vs. Input Voltage (Qg Parameters) 1.2 1.1 1.0 0.9 0 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Power Consumption vs. Input Voltage (fosc Parameter) 1.2 1.1 1.0 0.9 0.8 0.7 ...

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    SAMPLE CIRCUIT MB3886 25 ...

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    MB3886 PARTS LIST COMPONENT ITEM Q1, Q3 FET Q2, Q4 FETKY TM D1, D3 Diode L1 Coil L2 Coil C2 OS-CON TM C3, C5, C6, C8 Ceramics Condenser TM C4 OS-CON C7 OS-CON TM C9 Ceramics Condenser C10 Ceramics Condenser ...

  • Page 27

    REFERENCE DATA Conversion Efficiency vs. Load Current (CH1) 100 Ta 3.3 V output 90 SW1 OFF SW2 Conversion Efficiency vs. Load Current (CH2) 100 output 90 SW1 ON ...

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    ... The worker must put on a grounding device containing 250 k • Do not apply a negative voltage. - Applying a negative voltage of 0 less to an LSI may generate a parasitic transistor, resulting in malfunction. ORDERING INFORMATION Model name MB3886PFV resistors in series. Package 30-pin plastic SSOP (FPT-30P-M02) ...

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    PACKAGE DIMENSION 30-pin plastic SSOP (FPT-30P-M02) * 9.70±0.10(.382±.004) INDEX 0.65±0.12(.0256±.0047) 9.10(.358)REF 1994 FUJITSU LIMITED F30003S-2C This dimension does not include resin protrusion. +0.20 1.25 –0.10 +.008 .049 –.004 0.10(.004) 5.60±0.10 7.60±0.20 6.60(.260) (.220±.004) (.299±.008) NOM "A" +0.10 ...

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    MB3886 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 ...