mb3881pff

Manufacturer Part Numbermb3881pff
Description8-ch Dc/dc Converter Ic With Synchronous Rectifier For Voltage Step-up And Step-down
ManufacturerFujitsu Microelectronics, Inc.
mb3881pff datasheet
 


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FUJITSU SEMICONDUCTOR
DATA SHEET
ASSP For Power Management Applications
-ch DC/DC Converter IC with Synchronous
8
Rectifier for Voltage Step-up and Step-down
MB3881
DESCRIPTION
The MB3881 a step-up/step-down type of 8-channel, DC/DC converter IC. It uses pulse width modulation (PWM)
and synchronous rectification, designed for low voltage, high efficiency, and compactness. This IC is ideal for
down conversion and up/down conversion (employing a step-up/step-down Zeta system enabling free I/O setting).
The MB3881 can use channel 8 as its own power supply to provide a wide range of supply voltages, allowing
itself to operate at low voltage.
In addition, the MB3881 contains a triangular wave oscillator which can operate in synchronization with an external
device, allowing the switching timing to be controlled externally. This contributes to reduction in switching noise,
facilitating system configuration.
The MB3881 is designed to be compact using the LQFP-64P package whose body size is 7
The IC is the best for the power supply for advanced portable equipment such as a camera integrated VTR.
FEATURES
• Supporting the step-up/step-down Zeta methods (CH1 to CH7)
• Supporting synchronous rectification (CH1, CH2)
• Low start-up voltage : 1.8 V (CH8)
• Power-supply voltage range : 4 V to 13 V (CH1 to CH7)
• Built-in high-precision reference voltage generator : 2.5 V
• Oscillation frequency range : 100 kHz to 800 kHz
• Built-in triangular wave oscillator capable of external synchronization
• Error amplifier output for soft start (CH1 to CH4, CH7)
PACKAGE
1%
64-pin plastic LQFP
(FPT-64P-M16)
DS04-27224-1E
7 mm.

mb3881pff Summary of contents

  • Page 1

    FUJITSU SEMICONDUCTOR DATA SHEET ASSP For Power Management Applications -ch DC/DC Converter IC with Synchronous 8 Rectifier for Voltage Step-up and Step-down MB3881 DESCRIPTION The MB3881 a step-up/step-down type of 8-channel, DC/DC converter IC. It uses pulse width modulation (PWM) ...

  • Page 2

    MB3881 PIN ASSIGNMENT GND(O)-2 1 RB8 2 DTC8 3 FB8 4 IN8 5 IN8 6 IN8(C) 7 IN8(C) 8 DTC7 9 FB7 10 IN7 11 IN7 12 DTC6 13 FB6 14 IN6 15 IN6 16 (CH5,CH6) 2 Output block 48 ...

  • Page 3

    PIN DESCRIPTION Pin No. Symbol 47 FB1 46 IN1 CH1 48 DTC1 50 OUT1-1 51 OUT1-2 44 FB2 43 IN2 CH2 45 DTC2 53 OUT2-1 54 OUT2-2 41 FB3 40 IN3 CH3 42 DTC3 56 OUT3 38 FB4 37 IN4 ...

  • Page 4

    MB3881 (Continued) Pin No. Symbol 4 FB8 5 IN8 6 IN8 7 IN8 (C) CH8 8 IN8 (C) 3 DTC8 2 RB8 64 OUT8 33 RT OSC SYNC 28 CTL-1 29 CTL-2 Control 30 CTL-3 31 CTL-4 ...

  • Page 5

    BLOCK DIAGRAM • General view FB1 IN1 DTC1 FB2 IN2 DTC2 45 FB3 41 IN3 DTC3 42 FB4 38 IN4 DTC4 39 FB5 IN5 IN5(C) IN5 22 DTC5 FB6 14 IN6 IN6(C) 17 IN6 16 OVP 18 DTC6 13 FB7 ...

  • Page 6

    MB3881 • Enlarged view of A FB1 47 46 IN1 48 DTC1 FB2 44 IN2 43 DTC2 45 FB3 41 IN3 40 DTC3 42 FB4 38 IN4 37 DTC4 39 6 CH1 PWM Comp.1-1 Drive Error 1-1 Amp.1 PWM Comp.1-2 ...

  • Page 7

    Enlarged view FB5 Error Amp.5 IN5 21 0.6 V SCP Comp.5 23 IN5(C) IN5 22 19 DTC5 FB6 14 Error Amp.6 15 IN6 0.6 V SCP Comp.6 IN6(C) 17 IN6 16 OVP 18 DTC6 13 FB7 ...

  • Page 8

    MB3881 • Enlarged view of C FB8 4 Error Amp.8 IN8 5 IN8 6 SCP Comp.8 IN8(C) 7 IN8( DTC8 CTL CTL CTL-2 29 Logic CTL-3 30 CTL-4 31 Buff 0.8 Buff 32 CS ...

  • Page 9

    ABSOLUTE MAXIMUM RATINGS Parameter Symbol V CC Power supply voltage V DD Output current I O Output peak current I O Power dissipation P D Storage temperature Tstg * : The packages are mounted on the epoxy board (10 cm ...

  • Page 10

    MB3881 ELECTRICAL CHARACTERISTICS Parameter Reference voltage Output voltage temperature stability Input stability Load stability Short-circuit output current Threshold voltage Hysteresis width Reset voltage Threshold voltage Input standby voltage Charge current Threshold voltage Input standby voltage Input latch voltage Input source ...

  • Page 11

    Sym- Parameter Threshold voltage V temperature stability T Input bias current Voltage gain Frequency bandwidth Output voltage Output source current I SOURCE Output sink current Input offset voltage V temperature stability T Input bias current Common mode input voltage ...

  • Page 12

    MB3881 (Continued) Parameter Input offset voltage Input bias current Common mode input voltage range Voltage gain Frequency bandwidth Output voltage Output source current Output sink current Threshold voltage Input bias current Input offset voltage Input bias current Common mode input ...

  • Page 13

    Sym- Parameter bol V Threshold voltage V Output source current I SOURCE Output sink current I R Output ON resistor R Output source current I SOURCE Output sink current I R Output ON resistor R Output source current I ...

  • Page 14

    MB3881 TYPICAL CHARACTERISTICS Power supply current vs. power supply voltage CTL 1 CTL Power supply voltage V Reference voltage vs. ambient temperature 2.56 VCC 9 ...

  • Page 15

    Triangular wave upper and lower limit voltage vs.triangular wave oscillator frequency 1 Ta 0.9 VCC 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0 100 200 300 400 500 600 700 800 900 1000 Triangular wave oscillator frequency ...

  • Page 16

    MB3881 (Continued) Error amplifier gain and phase vs. frequency (CH1 100 k Frequency f (Hz) Error amplifier gain and phase vs. frequency (CH5 ...

  • Page 17

    FUNCTIONS 1. DC-DC Converter Functions (1) Reference voltage generator The reference voltage generator generates a temperature-compensated reference voltage (typically : = 2.5 V) from the voltage supplied from the power supply terminal (pin 27). The voltage is used as the ...

  • Page 18

    MB3881 2. Channel Control Function Channels are turned on and off depending on the voltage levels at the CTL-1 terminal (pin 28), CTL-2 terminal (pin 29), CTL-3 terminal (pin 30),and CTL-4 terminal (pin 31). Voltage level at CTL pin CTL-1 ...

  • Page 19

    Soft Start Operation (1) Description • When the CTL-1 to CTL-4 pins are driven high (“H” level) The channel-8 output voltage is soft-started by the capacitor (C The capacitor (Cs) connected to the CS terminal (pin 32) starts being ...

  • Page 20

    MB3881 • When the CTL-2 (CTL-4) terminal is driven low (“L” level) after channels and 8 have been soft-started The capacitor (Cs) connected to the CS terminal (pin 32) starts being charged. The channel-2 (channel-7) output voltage ...

  • Page 21

    Setting Soft Start • Channel-8 soft start Channel 8 can be soft-started by connecting a capacitor between the DTC8 terminal (pin 3) and GND. The soft start time depends on the input voltage and load current. • Channel 1 ...

  • Page 22

    MB3881 SETTING THE OUTPUT VOLTAGE • CH1 to CH4 V O FB1 R1 IN1 R2 • CH5, CH6 IN5 R2 IN5(C) IN5 OVP Error Amp.1 46 1.25 V SCP Comp.1 1 Error ...

  • Page 23

    CH7 V O FB7 IN7 R2 12 IN7 • CH8 V O FB8 R1 IN8 R2 Ra IN8 Rb IN8(C) IN8( • IN7 V O Error Amp.7 • IN7< ...

  • Page 24

    MB3881 SAMPLE POWER SUPPLY USING CHANNEL 8 AS SELF-POWER SUPPLY Using channel 8 as the self-power supply, the MB3881 can support a wide range of supply voltages and operate at low input voltage (Vin 1.8 V). The following example shows ...

  • Page 25

    SETTING THE OUTPUT CURRENT The output circuit (drive 8) is structured as illustrated below (in the output circuit diagram). As found in “Output Current Waveform” below, the source current value of the output current waveform has a constant current setting. ...

  • Page 26

    MB3881 SETTING TIME CONSTANT FOR TIMER-LATCH SHORT-CIRCUIT PROTECTION CIRCUIT The short detection comparator (SCP comparator) in each channel monitors the output voltage. While the switching regulator load conditions are stable on all channels, the LOG_SCP output remains at "H" level, ...

  • Page 27

    SETTING FOR EXTERNAL SYNCHRONOUS OSCILLATION For external synchronous operation, connect the timing capacitor (C resistor ( the RT terminal (pin 33 this case, select the C and external synchronous signal excluding the setting ...

  • Page 28

    MB3881 TREATMENT WITHOUT USING CSCP When you do not use the timer-latch short protection circuit, connect the CSCP terminal (pin 26) to GND with the shortest distance TREATMENT FOR KILLING THE SOFT START FEATURE To disable the channel 1 to ...

  • Page 29

    SETTING THE DEAD TIME When the device is set for step-up inverted output based on the step-up or step-up/down Zeta method or flyback method, the FB pin voltage may reach and exceed the rectangular wave voltage due to load fluctuation. ...

  • Page 30

    MB3881 APPLICATION EXAMPLE • General view 30 Vo1 (2 VCC(O)- FB1 R1 47 OUT1-1 240 C21 A 50 0.1 F C33 C1 C13 2200 pF R17 2 ...

  • Page 31

    Enlarged view of A FB1 47 C21 A 0 R17 IN1 R18 20 k DTC1 48 FB2 44 C22 B 0.1 F R10 R19 IN2 R20 16 ...

  • Page 32

    MB3881 • Enlarged view of B FB5 20 E C25 0.1 F Vin R13 R25 5 (3 IN5 R26 20 k IN5(C) 23 Motor control 22 signal IN5 DTC5 19 FB6 14 F C26 0.1 ...

  • Page 33

    Enlarged view FB8 4 C28 0.1 F R31 R16 130 IN8 R32 10 k R39 IN8 R40 C46 CH8 IN8(C) R48 ...

  • Page 34

    MB3881 PARTS LIST COMPONENT ITEM PNP Tr Q8 NPN Tr Q9, Q10 FET Diode D10 to D13 Diode L1 Coil L2, L3 Coil L4 Coil L5 Coil L6 Coil L7 Coil L8, L9 Coil ...

  • Page 35

    COMPONENT ITEM R33 Resistor R34 Resistor R35 Resistor R36 Resistor R37 Resistor R38 Resistor R39 Resistor R40 Resistor R41 Resistor R42 Resistor R43 Resistor R44 Resistor R45 Resistor R46 Resistor R47 Resistor R48 Resistor R49 Resistor Note : SANYO ...

  • Page 36

    MB3881 REFERENCE DATA Conversion efficiency vs. load current (CH1 : Down conversion method with synchronous rectification output VCC (O) 86 VSS ( 100 150 200 ...

  • Page 37

    Conversion efficiency vs. load current (CH3 : Zeta method ) ouputt VCC (O) 72 VSS ( 100 150 200 250 300 350 ...

  • Page 38

    ... Working personnel should be grounded with resistance of 250 between body and ground 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 MB3881PFF 38 Package 64-pin plastic LQFP (FPT-64P-M16) Remarks ...

  • Page 39

    PACKAGE DIMENSION 64-pin plastic LQFP (FPT-64P-M16) 9.00±0.20(.354±.008)SQ 7.00±0.20(.276±.008) INDEX 64 1 0.40(.016) 0.18±0.03 (.007±.001) 1999 FUJITSU LIMITED F64027SC-2-1 C 1.70(.067)MAX 1.40±0.10 (.055±.004) 0.10±0.10 33 (.004±.004) 32 Details of "A" part 0.10(.004) 17 "A" 16 +0.10 0.15 –0.05 +.004 ...

  • Page 40

    ... 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, USA Tel: +1-408-922-9000 Fax: +1-408-922-9179 Customer Response Center Mon. - Fri (PST) ...