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FUJITSU SEMICONDUCTOR
DS04-27231-3E
DATA SHEET
ASSP For Power Management Applications
(General Purpose DC/DC Converter)
2-ch DC/DC Converter IC
with Overcurrent Protection
MB39A104
n DESCRIPTION
The MB39A104 is a 2-channel DC/DC converter IC using pulse width modulation (PWM), incorporating an
overcurrent protection circuit (requiring no current sense resistor). This IC is ideal for down conversion.
Operating at high frequency reduces the value of coil.
This is ideal for built-in power supply
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MB39A104 n PIN ASSIGNMENTS (TOP VIEW) VCCO : 1 24 : CTL VH : 2 23 : GNDO OUT1 : 3 22 : OUT2 VS1 : 4 21 : VS2 ILIM1 : 5 20 : ILIM2 DTC1 : 6 19 : DTC2 VCC : 7 18 : GND CSCP : 8 17 : VREF FB1 : 9 16 : FB2 - INE1 : 10 15 : - INE2 CS1 : 11 14 : CS2 RT : 12 13 : CT (FPT-24P-M03) 2
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MB39A104 n PIN DESCRIPTION Pin No. Symbol I/O Descriptions 1VCCO Output circuit power supply terminal (Connect to same potential as VCC pin.) 2 VH O Power supply terminal for FET drive circuit (VH = VCC - 5 V) 3 OUT1 O External Pch MOS FET gate drive terminal 4 VS1 I Overcurrent protection circuit input terminal Overcurrent protection circuit detection resistor connection terminal. Set 5ILIM1 I overcurrent detection reference voltage depending on external resistor and internal current reso
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MB39A104 n BLOCK DIAGRAM - INE1 10 L priority CH1 1 VCCO VREF Error PWM Amp1 10 m A - Comp.1 + + Drive1 CS1 11 + + Pch 3 OUT1 - 1.24 V L priority FB1 9 IO = 200 mA at VCCO = 12 V - 4 VS1 Current Protection 5 ILIM1 Logic DTC1 6 - INE2 15 CH2 L priority VREF Error PWM Amp2 10 m A - Comp.2 + + Drive2 CS2 14 + + Pch 22 OUT2 - 1.24 V L priority FB2 16 IO = 200 mA DTC2 19 at VCCO = 12 V - 21 VS2 Current H priority H: at SCP Protection 20 ILIM2 SCP Logic Comp. - (3.1 V) H: at OCP VCC - 5 V 2 VH VH Bia
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MB39A104 n ABSOLUTE MAXIMUM RATINGS Rating Parameter Symbol Condition Unit Min Max Power supply voltage VCC VCC, VCCO terminal 20 V Output current IO OUT1, OUT2 terminal 60 mA Output peak current IOP Duty £ 5% (t = 1/fOSC· Duty) 700 mA Power dissipation PD Ta £ +25 C 740* mW Storage temperature TSTG - 55 +125 C * : The packages are mounted on the epoxy board (10 cm · 10 cm). WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temper
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MB39A104 n ELECTRICAL CHARACTERISTICS (VCC = VCCO = 12 V, VREF = 0 mA, Ta = +25 C) Value Parameter Symbol Pin No Conditions Unit Min Typ Max Output voltage VREF 17 Ta = +25 C 4.95 5.00 5.05 V Output voltage D VREF/ temperature 17 Ta = 0 C to +85 C 0.5* % VREF variation Input stability Line 17 VCC = 7 V to 19 V 310 mV Load stability Load 17 VREF = 0 mA to - 1 mA 110 mV Short-cuircuit IOS 17 VREF = 1 V - 50 - 25 - 12 mA output current VTLH 17 VREF = 2.62.83.0V Threshold voltage
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MB39A104 (Continued) (VCC = VCCO = 12 V, VREF = 0 mA, Ta = +25 C) Value Parameter Symbol Pin No. Conditions Unit Min Typ Max Frequency BW 9, 16 AV = 0 dB 1.6* MHz bandwidth VOH 9, 16 4.7 4.9 V Output voltage VOL 9, 16 40 200 mV Output source ISOURCE 9, 16 FB1 = FB2 = 2 V - 2 -1mA current Output sink current ISINK 9, 16 FB1 = FB2 = 2 V 150 200 m A VT0 6, 19 Duty cycle = 0 % 1.4 1.5 V Threshold voltage VT100 6, 19 Duty cycle = Dtr 2.5 2.6 V Input current IDTC 6, 19 DTC1 = DTC
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MB39A104 n TYPICAL CHARACTERISTICS Power Supply Current vs. Power Supply Voltage Reference Voltage vs. Power Supply Voltage 10 10 Ta = +25 C Ta = +25 C CTL = 5 V CTL = 5 V VREF = 0 mA 8 8 6 6 4 4 2 2 0 0 0 5 10 15 20 0 5 10 15 20 Power supply voltage VCC (V) Power supply voltage VCC (V) Reference Voltage vs. Ambient Temperature Reference Voltage vs. Ambient Temperature 2.0 10 VCC = 12 V Ta = +25 C 1.5 CTL = 5 V VCC = 12 V VREF = 0 mA CTL = 5 V 8 1.0 D 0.5 6 0.0 4 - 0.5 - 1.0 2 - 1.5 - 2.0
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MB39A104 Triangular Wave Oscillation Frequency Triangular Wave Oscillation Frequency vs. Timing Capacitor vs. Timing Resistor 10000 10000 Ta = +25 C Ta = +25 C VCC = 12 V VCC = 12 V CTL = 5 V CTL = 5 V 1000 1000 RT = 11 kW CT = 39 pF RT = 24 kW 100 100 CT = 560 pF RT = 130 kW RT = 68 kW CT = 220 pF CT = 100 pF 10 10 10 100 1000 10000 1 10 100 1000 Timing resistor RT (kW ) Timing capacitor CT (pF) Triangular Wave Upper and Lower Limit Voltage Triangular Wave Upper and Lower Limit Voltage
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MB39A104 (Continued) Error Amplifier, Gain, Phase vs. Frequency Ta = +25 C 40 180 VCC = 12 V 240 kW AV 30 j 20 90 10 kW (15) 1 m F 10 + - 10 f 0 0 2.4 kW IN 9 + 11 - 10 (16) 10 kW OUT + (14) Error Amp1 - 20 - 90 (Error Amp2) 1.24 V - 30 - 40 - 180 100 1 k 10 k 100 k 1 M 10 M Frequency f (Hz) Power Dissipation vs. Ambient Temperature 1000 800 740 600 400 200 0 - 40 - 20 0 20 40 60 80 100 Ambient temperature Ta ( C) 10 Gain AV (dB) Power dissipation PD (mW) Phase (deg)
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MB39A104 n FUNCTIONS 1. DC/DC Converter Functions (1) Reference voltage block (REF) The reference voltage circuit generates a temperature-compensated reference voltage (5.0 V Typ) from the voltage supplied from the power supply terminal (pin 7). The voltage is used as the reference voltage for the IC’s internal circuitry. The reference voltage can supply a load current of up to 1 mA to an external device through the VREF terminal (pin 17). (2) Triangular-wave oscillator block (OSC) The tria
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MB39A104 2. Control Function When CTL terminal (pin 24) is “L” level, IC becomes the standby mode. The power supply current is 10 m A (Max) at the standby mode. On/Off Setting Conditions CTL Power L OFF (Standby) H ON (Operating) 3. Protective Functions (1) Timer-latch overcurrent protection circuit block (OCP) The timer-latch overcurrent protection circuit is actuated upon completion of the soft-start period. When an overcurrent flows, the circuit detects the increase in the voltage between
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MB39A104 n SETTING THE OUTPUT VOLTAGE • Output Voltage Setting Circuit VO R1 (- INE2) 15 Error Amp 10 - 1.24 VO (V) = (R1 + R2) - INE1 + R2 + R2 1.24 V (CS2) 14 CS1 11 n SETTING THE TRIANGULAR OSCILLATION FREQUENCY The triangular oscillation frequency is determined by the timing capacitor (CT) connected to the CT terminal (pin 13), and the timing resistor (RT) connected to the RT terminal (pin 12). Moreover, it shifts more greatly than the caluculated values according to the constant of timing r
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MB39A104 n SETTING THE SOFT-START AND DISCHARGE TIMES To prevent rush currents when the IC is turned on, you can set a soft-start by connecting soft-start capacitors (CS1 and CS2) to the CS1 terminal (pin 11) for channel 1 and the CS2 terminal (pin 14) for channel 2, respectively. When CTL terminal (pin 24) goes to “H” level and IC starts (VCC ‡ UVLO threshold voltage), the external soft- start capacitors (CS1 and CS2) connected to CS1 and CS2 terminals are charged at 10 m A. The error amplifie
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MB39A104 • Soft-Start Circuit VREF VO R1 10 m A - INE1 10 (- INE2) 15 R2 L priority Error Amp - CH ON/OFF signal + 11 + L : ON, H : OFF CS1 14 (CS2) 1.24 V CS1 (CS2) FB1 9 (FB2) 16 UVLO 15
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MB39A104 n TREATMENT WITHOUT USING CS TERMINAL When not using the soft-start function, open the CS1 terminal (pin 11) and the CS2 terminal (pin 14) . • Without Setting Soft-Start Time “OPEN” “OPEN” 11 CS1 CS2 14 16
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MB39A104 n ABOUT TIMER-LATCH PROTECTION CIRCUIT 1. Setting Timer-Latch Overcurrent Protection Detection Current The overcurrent protection circuit is actuated upon completion of the soft-start period. When an overcurrent flows, the circuit detects the increase in the voltage between the FET’s drain and source using the external FET ON resistor (RON), actuates the timer circuit, and starts charging the capacitor CSCP connected to the CSCP terminal (pin 8). If the overcurrent remains flowing bey
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MB39A104 Overcurrent Protection Circuit: Range of Operation When an overcurrent flow occurs, if the increased voltage between the drain and source of the FET is detected by means of the external FET (Q1) resistor, operational stability is lost when the external FET (Q1) ON interval determined by the oscillation frequency, input voltage, and output voltage falls below 450 ns. Therefore, the circuit should be used within a range that ensures that the ON interval does not fall below 450ns, accordin
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MB39A104 2. Setting Time Constant for Timer-Latch Short-Circuit Protection Circuit Each channel uses the short-circuit detection comparator (SCP Comp.) to always compare the error amplifier¢ s output level to the reference voltage (3.1 V Typ). While DC/DC converter load conditions are stable on all channels, the short-circuit detection comparator output remains at “L” level, and the CSCP terminal (pin 8) is held at “L” level. If the load condition on a channel changes rapidly due to a short-circ
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MB39A104 n TREATMENT WITHOUT USING CSCP TERMINAL When not using the timer-latch short-circuit protection circuit, connect the CSCP terminal (pin 8) to GND with the shortest distance. • Treatment without using CSCP GND 18 8 CSCP n RESETTING THE LATCH OF EACH PROTECTION CIRCUIT When the overcurrent, or short-circuit protection circuit detects each abnormality, it sets the latch to fix the output at the "L" level. To reset the actuated protection circuit, either the power supply turn off and on ag
