Instruction/ maintenance manual of the product MB39A105 Fujitsu
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DS04-27233-2E FUJITSU SEMICONDUCT OR DA T A S H E E T ASSP F or P o wer Supply Applications (Gener al Pur pose DC/DC Con v er ter) 1-c h DC/DC Con ver ter IC f or low v o ltage MB39A105 ■ ■ ■ ■ DESCRIPTION The MB39A105 is 1-channel DC/DC conv er ter IC using pulse width modulation (PWM).
MB39A105 2 ■ ■ ■ ■ PIN ASSIGNMENT (TOP VIEW) (FPT-8P-M05) − INE CSCP VCC SCPOD 1 2 3 4 FB RT GND OUT 8 7 6 5.
MB39A105 3 ■ ■ ■ ■ PIN DESCRIPTION Pin No. Symbol I/O Descriptions 1 − INE I Error amplifiers (Error Amp) inverted input terminal 2C S C P Timer-latch short-circuit protection capacitor .
MB39A105 4 ■ ■ ■ ■ BLOCK DIA GRAM + − − + + + − + − 1 8 2 − INE FB CSCP 7 RT 6 5 GND OUT 4 3 SCPOD VCC VREF VREF Error Amp SCP Comp. PWM Comp. Drive Nch I O = 400 mA at VCC = 3.3 V (0.5 V ± 1%) ± 10% (1.0 V) UVLO OSC SQ R (0.9 V) (0.
MB39A105 5 ■ ■ ■ ■ ABSOLUTE MAXIMUM RA TINGS * : The packages are mounted on the epo xy board (10 cm × 10 cm). W ARNING: Semiconductor de vices can be per manently damaged by application of stress (v oltage, current, temperature , etc.) in e xcess of absolute maximum ratings.
MB39A105 6 ■ ■ ■ ■ ELECTRICAL CHARA CTERISTICS (VCC = 3.3 V, T a = + 25 ° C) *: Standard design v alue. Parameter Symbol Pin No Conditions Va l u e Unit Min Typ Max 1. Under voltage lockout protection circuit block [UVLO] Threshold voltage V TLH 3V C C = 1.
MB39A105 7 ■ ■ ■ ■ TYPICAL CHARA CTERISTICS (Continued) Power supply current I CC (mA) Power supply current I CC (mA) Power Supply Current vs. Power Supply Voltage Power Supply Current vs.
MB39A105 8 (Continued) Triangular Wave Oscillation Frequency vs. Timing Resistor Triangular wave oscillation frequency f OSC (kHz) Timing resistor R T (k Ω ) Triangular Wave Oscillation Frequency vs. Ambient Temperature Triangular wave oscillation frequency f OSC (kHz) Ambient temperature Ta ( ° C) Error Amplifier Gain and Phase vs.
MB39A105 9 (Continued) 600 500 400 300 200 100 0 490 − 40 − 20 0 20 40 60 80 100 Power Dissipation vs. Ambient Temperature Power dissipation P D (mW) Ambient temperature Ta ( ° C).
MB39A105 10 ■ ■ ■ ■ FUNCTIONS 1. DC/DC Con ver ter Functions (1) T riangular-wa ve oscillator block (OSC) The triangular wav e oscillator incor porates a timing resistor connected to R T ter minal (pin 7) to generate triangular oscillation wav ef or m amplitude of 0.
MB39A105 11 2. P ower Contr ol Function A s witch in ser ies with a resistor connected with the R T ter minal (pin 7) allows y ou to tur n on or tur n off the power . 3. Pr otective Functions (1) Timer -latch short-circuit pr otection circuit (SCP) Shor t-circuit detection comparator detects the error amplifier output voltage le vel.
MB39A105 12 ■ ■ ■ ■ SETTING THE OUTPUT V OL T A GE ■ ■ ■ ■ SETTING THE TRIANGULAR OSCILLA TION FREQUENCY The triangular oscillation frequency is deter mined by the timing resistor (R T ) connected to the R T ter minal (pin 7) . T r iangular oscillation frequency : f osc − + + V O R1 R2 − INE CSCP Error Amp (0.
MB39A105 13 ■ ■ ■ ■ SETTING THE SOFT-ST ART TIMES T o prev ent rush currents when the IC is tur ned on, you can set a soft-star t by connecting soft-star t capacitors (C SCP ) to the CSCP ter minal (pin 2).
MB39A105 14 ■ ■ ■ ■ SETTING TIME CONST ANT FOR TIMER-LA TCH SHOR T -CIRCUIT PR O TECTION CIRCUIT The error amplifier’ s output lev el alawa ys does the compar ison operation with the shor t-circuit protection com- parator (SCP Comp .) to the ref erence voltage .
MB39A105 15 1.0 V 0.9 V 0.8 V 0.7 V 0.3 V t • Soft - star t and shor t-circuit pr otection circuit timing c h ar t FB voltage CSCP voltage OSC amplifier Output short Output short Soft-start time t S.
MB39A105 16 ■ ■ ■ ■ I/O EQUIV ALENT 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.
MB39A105 17 ■ ■ ■ ■ APPLICA TION 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.
MB39A105 18 ■ ■ ■ ■ P ART S LIST Note : SANY O : SANY O Electr ic Co ., Ltd. SUMID A : SUMID A Electr ic Co ., Ltd. TDK : TDK Cor poration NEC/T OKIN : NEC T OKIN Cor poration ssm : SUSUMU Co ., Ltd. COMPONENT ITEM SPECIFICA TION VENDOR P ARTS No.
MB39A105 19 ■ ■ ■ ■ SELECTION OF COMPONENTS • Nch MOS FET The N-ch MOSFET f or switching use should be r ated f or at least 20% more than the maximum output voltage . T o minimize continuity loss , use a FET with low R DS(ON) between the drain and source .
MB39A105 20 The abov e power dissipation figures f or 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 th.
MB39A105 21 Example: Inductance v alues der ived from the abo ve f or mulas are values that pro vide sufficient margin for contin uous operation at maxim um load current, but at which contin uous operation is not possible at light loads . It is therefore necessar y to deter mine the load lev el at which continuous operation becomes possib le.
MB39A105 22 P eak-to-peak value: • Flybac k diode The flyback diode is gener ally used as a Shottky barr ier diode (SBD) when the re verse v oltage to the diode is less than 40V .
MB39A105 23 • Smoothing Capacitor The smoothing capacitor is an indispensable element f or reducing r ipple voltage in output. In selecting a smooth- ing capacitor it is essential to consider equiv alent ser ies resistance (ESR) and allowab le r ipple current.
MB39A105 24 ■ ■ ■ ■ REFERENCE D A T A Vin = 1.8 V Vin = 3.3 V Vin = 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.
MB39A105 25 ■ ■ ■ ■ USA GE PRECA UTION • Printed cir cuit board gr ound lines should be set up with consideration for common impedance. • T ake appropriate static electricity measures. • Containers f or semiconductor materials should ha v e anti-static protection or be made of conductive material.
MB39A105 26 ■ ■ ■ ■ P A CKA GE 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.
MB39A105 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.
An important point after buying a device Fujitsu MB39A105 (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
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