Fujitsu MB39A105 - Manuals

MB39A105 6 ■ ■ ■ ■ ELECTRICAL CHARACTERISTICS (VCC = 3.3 V, Ta = + 25 ° C) *: Standard design value. Parameter Symbol Pin No Conditions Value Unit Min Typ Max 1. Under voltage lockout protection circuit block [UVLO] Threshold voltage V TLH 3 VCC = 1.15 1.35 1.55 V 2. Short-circuit protection block [...

MB39A105 7 ■ ■ ■ ■ TYPICAL CHARACTERISTICS (Continued) Power supply current I CC (mA) Power supply current I CC (mA) Power Supply Current vs. Power Supply Voltage Power Supply Current vs. RT Terminal Current Power supply voltage V CC (V) RT terminal current I RT ( µ A) Error Amplifier Threshold Volt...

MB39A105 10 ■ ■ ■ ■ FUNCTIONS 1. DC/DC Converter Functions (1) Triangular-wave oscillator block (OSC) The triangular wave oscillator incorporates a timing resistor connected to RT terminal (pin 7) to generate triangular oscillation waveform amplitude of 0.3 V to 0.7 V.The triangular waveforms are in...

MB39A105 11 2. Power Control Function A switch in series with a resistor connected with the RT terminal (pin 7) allows you to turn on or turn off the power. 3. Protective Functions (1) Timer-latch short-circuit protection circuit (SCP) Short-circuit detection comparator detects the error amplifier o...

MB39A105 12 ■ ■ ■ ■ SETTING THE OUTPUT VOLTAGE ■ ■ ■ ■ SETTING THE TRIANGULAR OSCILLATION FREQUENCY The triangular oscillation frequency is determined by the timing resistor (R T ) connected to the RT terminal (pin 7) . Triangular oscillation frequency : fosc − + + V O R1 R2 − INE CSCP ErrorAmp (0.5...

MB39A105 13 ■ ■ ■ ■ SETTING THE SOFT-START TIMES To prevent rush currents when the IC is turned on, you can set a soft-star t by connecting soft-start capacitors(C SCP ) to the CSCP terminal (pin 2). When IC starts (V CC ≥ UVLO threshold voltage), the external soft-start capacitors (C SCP ) connecte...

MB39A105 14 ■ ■ ■ ■ SETTING TIME CONSTANT FOR TIMER-LATCH SHORT-CIRCUIT PROTECTION CIRCUIT The error amplifier’s output level alaways does the comparison operation with the short-circuit protection com-parator (SCP Comp.) to the reference voltage.While DC/DC converter load conditions are stable, the...

MB39A105 15 1.0 V 0.9 V 0.8 V 0.7 V 0.3 V t • Soft - start and short-circuit protection circuit timing chart FB voltage CSCP voltage OSC amplifier Output short Output short Soft-start timet S Short-circuit detection timet CSCP

MB39A105 16 ■ ■ ■ ■ I/O EQUIVALENT CIRCUIT 3 6 2 CSCP VCC GND SCPOD GND VCC 4 +− CSCP 1.0 V − INE CS GND VCC (1.27 V) FB 0.5 V 1 8 RT GND VCC 7 +− 0.33 V 〈〈 Soft-start block (CS) 〉〉 〈〈 Short-circuit protection circuit block (SCP) 〉〉 〈〈 Triangular wave oscillator block (RT) 〉〉 〈〈 Error amplifier bloc...

MB39A105 17 ■ ■ ■ ■ APPLICATION EXAMPLE + − − + + + − − + A A R5 43 k Ω R6 330 k Ω R8 100 k Ω R7 22 k Ω R4 51 k Ω R11 100 k Ω R1 7.5 k Ω ON/OFF CTL (L : OFF, H : ON) C9 0.1 µ F C8 0.22 µ F C4 4.7 µ F C3 4.7 µ F C2 4.7 µ F C1 0.1 µ F L1 6.8 µ H C5 4.7 µ F C6 4.7 µ F C7 0.1 µ F D1 V O (9.0 V) Q2 Q1 1 ...

MB39A105 18 ■ ■ ■ ■ PARTS LIST Note : SANYO : SANYO Electric Co., Ltd. SUMIDA : SUMIDA Electric Co., Ltd.TDK : TDK Corporation NEC/TOKIN : NEC TOKIN Corporationssm : SUSUMU Co., Ltd. COMPONENT ITEM SPECIFICATION VENDOR PARTS No. Q1 Pch FET VDS = 20 V, ID = − 2 A (Max) SANYO MCH3306 Q2, Q3 Nch FET VD...

MB39A105 19 ■ ■ ■ ■ SELECTION OF COMPONENTS • Nch MOS FET The N-ch MOSFET for switching use should be rated for at least 20% more than the maximum output voltage.To minimize continuity loss, use a FET with low R DS(ON) between the drain and source. For high output voltage and high frequency operatio...

MB39A105 20 The above power dissipation figures for the MCH3405 is satisfied with ample margin at 0.8 W. • Inductors In selecting inductors, it is of course essential not to apply more current than the rated capacity of the inductor,but also to note that the lower limit for ripple current is a criti...

MB39A105 22 Peak-to-peak value: • Flyback diode The flyback diode is generally used as a Shottky barrier diode (SBD) when the reverse voltage to the diode isless than 40V. The SBD has the characteristics of higher speed in terms of faster reverse recovery time, andlower forward voltage, and is ideal...

MB39A105 23 • Smoothing Capacitor The smoothing capacitor is an indispensable element for reducing ripple voltage in output. In selecting a smooth-ing capacitor it is essential to consider equivalent series resistance (ESR) and allowable ripple current. HigherESR means higher ripple voltage, so that...

MB39A105 24 ■ ■ ■ ■ REFERENCE DATA Vin = 1.8 VVin = 3.3 VVin = 6.0 V 100 90 80 70 60 50 40 30 1 m 10 m 100 m 1 Conversion efficiency η ( % ) Load current I L (A) Conversion Efficiency vs. Load current V G (V) 10 5 0 15 10 5 0 V D (V) t ( µ s) Ta = + 25 ° C VIN = 3.3 V V O = 9 V I O = 100 mA 0 1 2 3 ...

MB39A105 25 ■ ■ ■ ■ USAGE PRECAUTION • 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 mo...

MB39A105 26 ■ ■ ■ ■ PACKAGE DIMENSION 8-pin plastic TSSOP (FPT-8P-M05) Dimensions in mm (inches) 2002 FUJITSU LIMITED F08013Sc-1-1 3.00±0.10(.118±.004) 4.40±0.10 6.40±0.20 (.252±.008) (.173±.004) 1.10(.043)MAX 0.65(.026) 0.10(.004) 0~8 ˚ 0.22±0.10 (.009±.004) 0.127±0.03 (.0050±.001) 0.54(.021) 0.10±...

MB39A105 FUJITSU LIMITED All Rights Reserved. The contents of this document are subject to change without notice. Customers are advised to consult with FUJITSU salesrepresentatives before ordering. The information and circuit diagrams in this document arepresented as examples of semiconductor device...