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Fujitsu MB39A105 - page 1
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). This IC is ideal f or up conv ersion. The minimum ope ...
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Fujitsu MB39A105 - page 2
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 ...
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Fujitsu MB39A105 - page 3
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 connection terminal 3V C C Power supply terminal 4S C P O D O Open drain output terminal for short-circuit protection detection During timer-latch ...
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Fujitsu MB39A105 - page 4
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) (0.7 V) (0.3 V) bias RT Current VREF Power ON/OFF CTL VREF (1.27 V) L : UVLO release ...
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Fujitsu MB39A105 - page 5
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. Do not e xceed these ratings. ■ ■ ■ ■ RECOMMENDED OPERA ...
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Fujitsu MB39A105 - page 6
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 = 1.15 1.35 1.55 V 2. Short-circuit protection block [SCP] Threshold voltage V TH 2 ...
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Fujitsu MB39A105 - page 7
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. RT Terminal Current Power supply voltage V CC (V) RT terminal current I RT ( µ A) Error Amplifier Threshold Voltage V TH (V) Power supply voltage V CC ( ...
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Fujitsu MB39A105 - page 8
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. Frequency Fr ...
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Fujitsu MB39A105 - page 9
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) ...
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Fujitsu MB39A105 - page 10
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 0.3 V to 0.7 V . The triangular wav ef or m s are input to the PWM comparator ...
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Fujitsu MB39A105 - page 11
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. If the load co ...
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Fujitsu MB39A105 - page 12
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 (0.5 V) V O (V) = (R1 ...
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Fujitsu MB39A105 - page 13
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). When IC star ts (V CC ≥ UVLO threshold v oltage), the external soft-star t capacitors (C SCP ) connected to CSCP term inal are charge ...
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Fujitsu MB39A105 - page 14
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 . While DC/DC conv er ter load conditions are stable, the short-circuit detecti ...
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Fujitsu MB39A105 - page 15
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 Short-circuit detection time t CSCP ...
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Fujitsu MB39A105 - page 16
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 + − 0.33 V 〈〈 Soft-start block (CS) 〉〉 〈〈 Short-circuit protection circuit block (SCP) 〉〉 〈〈 Triangular wave oscillator block (RT) 〉〉 〈〈 Error amplifier block 〉 ...
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Fujitsu MB39A105 - page 17
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 4.7 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 8 2 − I ...
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Fujitsu MB39A105 - page 18
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. Q1 Pch FET VDS = 20 V, ID = − 2 A (Max) SANYO MCH3306 Q2, Q3 Nch FET VDS = 20 V, Qg = 4.5 nC ...
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Fujitsu MB39A105 - page 19
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 . For high output v oltage and high frequency operation, on/off-cycle s witching loss ...
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Fujitsu MB39A105 - page 20
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 than the r ated capacity of the inductor , but also to note that the lo wer limit f or r ipple current is a critical point that if reached will cause di ...
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Fujitsu MB39A105 - page 21
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. In th ...
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Fujitsu MB39A105 - page 22
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 . The SBD has the characteristics of higher speed in ter ms of f aster rev erse recov er y time, and low er f orw ard v oltage, and is ideal f or achieving high efficienc ...
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Fujitsu MB39A105 - page 23
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. Higher ESR means higher ripple voltage , so that to reduce ripple voltage it is necessa ...
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Fujitsu MB39A105 - page 24
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 = 3.3 V V O = 9 V I O = 100 mA 01234567 89 1 0 Switching Wave Form Ta = + ...
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Fujitsu MB39A105 - page 25
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. • After mounting, printed circuit b ...
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Fujitsu MB39A105 - page 26
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) 0.10(.004) 0~8 ˚ 0.22 ± 0.10 (.009 ± .004) 0.127 ± 0.03 (.0050 ± .001) 0.54(.021) 0.10 ± 0.10 ...
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Fujitsu MB39A105 - page 27
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. The information and circuit diagrams in this document are presented as examples of semiconductor device applications, and are not intended to be incorp ...
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