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Fujitsu MB39A105 Datasheet

1-ch dc/dc converter ic for low voltage.
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FUJITSU SEMICONDUCTOR
DATA SHEET
ASSP For Power Supply Applications
(General Purpose DC/DC Converter)
1-ch DC/DC Converter IC
for low voltage
MB39A105
DESCRIPTION
The MB39A105 is 1-channel DC/DC converter IC using pulse width modulation (PWM). This IC is ideal for up
conversion.
The minimum operating voltage is low (1.8 V) , and the MB39A105 is best for built-in power supply such as LCD
monitors. Also the short-circuit protection detection output function prevents input/output short on a chopper type
up-converter.
This product is covered by US Patent Number 6,147,477.
FEATURES
• Power supply voltage range : 1.8 V to 6 V
• Reference voltage accuracy :
• High-frequency operation capability : 1 MHz (Max)
• Built-in standby function: 0 A (Typ)
• Built-in timer-latch short-circuit protection circuit
• Built-in short-circuit protection detection output function
• Built-in soft-start circuit independent of loads
• Built-in totem-pole type output for Nch MOS FET
• Package : TSSOP-8P (Thickness 1.1 mm Max)
PACKAGE
1
8-pin plastic TSSOP
(FPT-8P-M05)
DS04-27233-2E

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   Summary of Contents for Fujitsu MB39A105

  • Page 1

    The MB39A105 is 1-channel DC/DC converter IC using pulse width modulation (PWM). This IC is ideal for up conversion. The minimum operating voltage is low (1.8 V) , and the MB39A105 is best for built-in power supply such as LCD monitors. Also the short-circuit protection detection output function prevents input/output short on a chopper type up-converter.

  • Page 2

    MB39A105 PIN ASSIGNMENT CSCP SCPOD (TOP VIEW) (FPT-8P-M05)

  • Page 3

    Open drain output terminal for short-circuit protection detection SCPOD External Nch FET gate drive terminal Ground terminal Triangular wave oscillation frequency setting resistor connection terminal Error Amplifier (Error Amp) output terminal Descriptions During timer-latch short-circuit protection operation : Output “High-Z” During normal operation : Output “L” MB39A105...

  • Page 4: Block Diagram

    MB39A105 BLOCK DIAGRAM VREF (0.5 V VREF Comp. CSCP (1.0 V) UVLO L : UVLO release SCPOD Error Amp Comp. (0.7 V) (0.3 V) (0.9 V) Drive 400 mA at VCC 3.3 V RT Current bias Power VREF ON/OFF VREF...

  • Page 5

    No warranty is made with respect to uses, operating conditions, or combinations not represented on the data sheet. Users considering application outside the listed conditions are advised to contact their FUJITSU representatives beforehand. Condition VCC terminal...

  • Page 6

    MB39A105 ELECTRICAL CHARACTERISTICS Parameter 1. Under voltage lockout Threshold voltage protection circuit block [UVLO] Threshold voltage Short-circuit detection time setting difference voltage Input source current 2. Short-circuit protection block Reset voltage [SCP] SCPOD terminal output leak current SCPOD terminal output on...

  • Page 7: Typical Characteristics

    TYPICAL CHARACTERISTICS Power Supply Current vs. Power Supply Voltage Power supply voltage V Error Amplifier Threshold Voltage vs. Power Supply Voltage Power supply voltage V Error Amplifier Threshold Voltage vs. Ambient Temperature 0.52 0.51 0.50 0.49 0.48 Ambient temperature Ta ( C) Power Supply Current vs.

  • Page 8

    MB39A105 Triangular Wave Oscillation Frequency vs. Timing Resistor 10000 1000 Timing resistor R Max On Duty vs. Triangular Wave Oscillation Frequency Triangular wave oscillation frequency f Error Amplifier Gain and Phase vs. Frequency 10 k 100 k Frequency f (Hz)

  • Page 9

    MB39A105 (Continued) Power Dissipation vs. Ambient Temperature Ambient temperature Ta ( C)

  • Page 10

    Also, it is possible to prevent rush current at power supply start-up by connecting a soft-start capacitor with the CSCP terminal (pin 2) which is the non-inverted input terminal for Error Amp. The use of Error Amp for soft-start detection makes it possible for a system to operate on a fixed soft-start time that is independent of the output load on the DC/DC converter.

  • Page 11

    FET, and sets the dead time to 100% while holding the CSCP terminal (pin 2) at the “L” level.

  • Page 12

    MB39A105 SETTING THE OUTPUT VOLTAGE • Output Voltage Setting Circuit CSCP SETTING THE TRIANGULAR OSCILLATION FREQUENCY The triangular oscillation frequency is determined by the timing resistor (R Triangular oscillation frequency : fosc 3750 fosc (kHz) : = (k ) Error (0.5 V)

  • Page 13

    : = 0.5 V : = 0 V Soft-start time (ts) • Soft-Start Circuit CSCP UVLO threshold voltage), the external soft-start CSCP terminal voltage Error Amp block INE voltage VREF 11 A L priority MB39A105 Error Amp (0.5 V) UVLO...

  • Page 14

    “L” level and can be used as a short-circuit operating detection signal during normal operation. To reset the actuated protection circuit, the power supply turn off and on again to lower the VCC terminal (pin 3) voltage to 1.1 V (Min) or less.

  • Page 15

    Soft start and short-circuit protection circuit timing chart • 1.0 V 0.9 V 0.8 V Output short Soft-start time MB39A105 FB voltage CSCP voltage 0.7 V amplifier 0.3 V Output short Short-circuit detection time CSCP...

  • Page 16

    MB39A105 I/O EQUIVALENT CIRCUIT Soft-start block (CS) protection element Triangular wave oscillator block (RT) 0.33 V Output block Short-circuit protection circuit block (SCP) protection CSCP element 1.0 V CSCP protection element (1.27 V) SCPOD Error amplifier block 0.5 V...

  • Page 17

    MB39A105 APPLICATION EXAMPLE...

  • Page 18

    MB39A105 PARTS LIST COMPONENT ITEM Pch FET Q2, Q3 Nch FET Diode Inductor C1, C7, C9 Ceramics Condenser C2 to C6 NeoCapacitor Ceramics Condenser Resistor Resistor Resistor Resistor Resistor R8, R11 Resistor Note : SANYO : SANYO Electric Co., Ltd.

  • Page 19

    0.25 2.4 (9 2.4) 0.68 (A) between the drain and source. For high output voltage DS(ON) 9 V, drain current I : = 160 m , tr DS (ON) IN(Min) MB39A105 0.94 A, Oscillation frequency 18 ns, tf 8 ns.

  • Page 20

    MB39A105 Duty DS (ON) 9 2.4 0.94 0.16 0.104 W D (Max) S (ON) 0.94 : = 0.013 W D (Max) D (Max) S (OFF) 1.20 0.007 W S (ON) S (OFF) : = 0.104 0.013 0.007 : = 0.124 W The above power dissipation figures for the MCH3405 is satisfied with ample margin at 0.8 W.

  • Page 21

    The peak value and peak-to-peak value of the ripple current can be determined by the following formulas. Peak value : I Peak-to-peak value : I Example: Using the CMD5D13-6R8 6.8 H (allowable tolerance 20 ) , rated current Peak value: 0.25 1.20 A 1.4 A 2.4) MB39A105...

  • Page 22

    MB39A105 Peak-to-peak value: IN (Min) 500 10 : = 0.654 A • Flyback diode The flyback diode is generally used as a Shottky barrier diode (SBD) when the reverse voltage to the diode is less than 40V. The SBD has the characteristics of higher speed in terms of faster reverse recovery time, and lower forward voltage, and is ideal for achieving high efficiency.

  • Page 23

    500 m , maximum allowable ripple current Equivalent series resistance 2 fC 0.18 0.654 252.7 m Capacitance value : C 2 f ( V ESR) 0.39 500 10 (0.18 0.654 0.167) 2.94 F Ripple current : IC 0.654 A 14.1 MB39A105...

  • Page 24

    MB39A105 REFERENCE DATA Conversion Efficiency vs. Load current 25 C 9 V output 10 m 100 m Load current Switching Wave Form Vin = 1.8 V Vin = 3.3 V Vin = 6.0 V 25 C 3.3 V 100 mA...

  • Page 25

    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 MB39A105PFT to 1 M between body and ground. Package 8-pin plastic TSSOP (FPT-8P-M05) MB39A105 Remarks...

  • Page 26: Package Dimension

    6.40 ± 0.20 (.173 ± .004) (.252 ± .008) INDEX Details of "A" part 1.10(.043)MAX "A" ˚ 0.65(.026) 0.22 ± 0.10 (.009 ± .004) 0.54(.021) 0.10 ± 0.10 (.004 ± .004) 0.10(.004) 1.95(.077) 2002 FUJITSU LIMITED F08013Sc-1-1 Dimensions in mm (inches)

  • Page 27

    (2) for use requiring extremely high reliability (i.e., submersible repeater and artificial satellite). Please note that Fujitsu will not be liable against you and/or any third party for any claims or damages arising in connection with above-mentioned uses of the products.

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