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FUJITSU SEMICONDUCTOR DATA SHEET DS04-27239-1E ASSP For Power Supply Applications (General-Purpose DC/DC Converter) 3-ch DC/DC Converter IC MB39A112 s DESCRIPTION The MB39A112 is a 3-channel DC/DC converter IC using pulse width modulation (PWM) , and the MB39A112 is suitable for down-conversion. 3-channel is built in TSSOP-20P package. Each channel can be controlled and soft-start. The MB39A112 contains a constant voltage bias circuit for output block, capable of implementing an efficient high-frequency DC/DC converter. It is ideal for built-in power supply such as ADSL modems. s REATURES * Supports for down-conversion (CH1 to CH3) * Power supply voltage range : 7 V to 25 V * Error amplifier threshold voltage : 1.00 V 1% (CH1) : 1.23 V 1% (CH2, CH3) * Oscillation frequency range : 250 kHz to 2.6 MHz * Built-in soft-start circuit independent of loads * Built-in timer-latch short-circuit protection circuit * Built-in totem-pole type output for P-channel MOS FET devices * Built-in constant voltage (VCCO - 5 V) bias circuit for output block s PACKAGE 20-pin plastic TSSOP (FPT-20P-M06) www..com www..com MB39A112 s PIN ASSIGNMENT (TOP VIEW) CS1 : 1 -INE1 : 2 FB1 : 3 VCC : 4 RT : 5 CT : 6 GND : 7 FB2 : 8 -INE2 : 9 CS2 : 10 20 : VCCO 19 : OUT1 18 : OUT2 17 : OUT3 16 : VH 15 : GNDO 14 : CSCP 13 : FB3 12 : -INE3 11 : CS3 (FPT-20P-M06) 2 MB39A112 s PIN DESCRIPTION Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Symbol CS1 - INE1 FB1 VCC RT CT GND FB2 - INE2 CS2 CS3 - INE3 FB3 CSCP GNDO VH OUT3 OUT2 OUT1 VCCO I/O I O O I I O O O O O Descriptions CH1 soft-start setting capacitor connection terminal. CH1 error amplifer inverted input terminal. CH1 error amplifer output terminal. Control circuit power supply terminal. Triangular-wave oscillation frequency setting resistor connection terminal. Triangular-wave oscillation frequency setting capacitor connection terminal. Ground terminal. CH2 error amplifier output terminal. CH2 error amplifier inverted input terminal. CH2 soft-start setting capacitor connection terminal. CH3 soft-start setting capacitor connection terminal. CH3 error amplifier inverted input terminal. CH3 error amplifier output terminal. Timer-latch short-circuit protection capacitor connection terminal. Ground terminal. Power supply terminal for driving output circuit. (VH = VCCO - 5 V) . CH3 external Pch MOS FET gate driving terminal. CH2 external Pch MOS FET gate driving terminal. CH1 external Pch MOS FET gate driving terminal. Power supply terminal for driving output circuit. (Connect to same potential as VCC terminal). 3 MB39A112 s BLOCK DIAGRAM Threshold voltage 1.0 V 1% VREF 10 A CS1 1 L priority -INE1 2 CH1 PWM Comp.1 Drive1 Pch 20 VCCO - + + 1.0 V Error Amp1 + - 19 OUT1 FB1 3 IO = 150 mA -INE2 9 VREF 10 A CS2 10 L priority Threshold voltage 1.23 V 1% - + + 1.23 V IO = 150 mA Error Amp2 + - PWM Comp.2 CH2 Drive2 Pch 18 OUT2 FB2 8 -INE3 12 10 A CS3 11 Threshold voltage 1.23 V 1% VREF - + + 1.23 V IO = 150 mA Error Amp3 + - PWM Comp.3 CH3 Drive3 Pch 17 OUT3 L priority FB3 13 H priority SCP Comp. + + + - 2.7 V VCCO - 5 V Bias Voltage VH 16 VH SCP 15 GNDO H: at SCP CSCP 14 2.5 V 2.0 V OSC UVLO Error Amp Power Supply SCP Comp. Power Supply 4 VCC H: UVLO release bias 3.5 V VREF ErrorAmp Reference 1.0 V/1.23 V VR Power ON/OFF CTL GND 5 RT 6 CT 7 GND 4 MB39A112 s ABSOLUTE MAXIMUM RATINGS Parameter Power supply voltage Output current Peak output current Power dissipation Storage temperature Symbol Vcc Io IOP PD TSTG Conditions VCC, VCCO terminal OUT1, OUT2, OUT3 terminal Duty 5 % (t = 1/fosc x Duty) Ta + 25 C Rating Min - 55 Max 28 20 400 1280* + 125 Unit V mA mA mW C * : The package is mounted on the dual-sided epoxy board (10 cm x 10 cm) . WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings. s RECOMMENDED OPERATING CONDITIONS Parameter Power supply voltage Input voltage Output current Oscillation frequency Timing capacitor Timing resistor VH terminal capacitor Soft-start capacitor Short-circuit detection capacitor Operating ambient temperature Symbol Vcc VIN IO IVH fosc CT RT CVH CS CSCP Ta VH terminal CS1, CS2, CS3 terminal CSCP terminal Conditions VCC, VCCO terminal - INE terminal OUT1, OUT2, OUT3 terminal VH terminal Value Min 7 0 - 15 0 250 22 4.7 - 30 Typ 12 - 1200 100 10 0.1 0.1 0.01 + 25 Max 25 Vcc - 1.8 15 30 2600 1000 22 1.0 1.0 1.0 + 85 Unit V V mA mA kHz pF k F F F C WARNING: The recommended operating conditions are required in order to ensure the normal operation of the semiconductor device. All of the device's electrical characteristics are warranted when the device is operated within these ranges. Always use semiconductor devices within their recommended operating condition ranges. Operation outside these ranges may adversely affect reliability and could result in device failure. 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. 5 MB39A112 s ELECTRICAL CHARACTERISTICS (VCC = VCCO = 12 V, Ta = + 25 C) Parameter Undervoltage Threshold voltage Lockout Protection Circuit Block Hysteresis width [UVLO] Short-circuit Protection Circuit Block [SCP] Triangular Wave Oscillator Block [OSC] Soft-start Block [CS1, CS2, CS3] Threshold voltage Input source current Reset voltage Oscillation frequency SymPin No. bol VTH VHYS VTH ICSCP VRST 4 4 14 14 4 VCC = CT = 100 pF, RT = 10 k Conditions VCC = Value Min 6.35 0.67 - 1.4 6.2 Typ 6.55 0.15 0.72 - 1.0 6.4 Max 6.75 0.77 - 0.6 6.6 Unit V V V A V fosc 17 to 19 1080 1200 1320 kHz Charge current ICS 1, 10, 11 2 2 3 3 3 3 3 3 9, 12 9, 12 8, 13 8, 13 8, 13 8, 13 8, 13 8, 13 FB1 = 2.25 V - INE1 = 0 V DC AV = 0dB FB1 = 2.25 V FB1 = 2.25 V FB2 = FB3 = 2.25 V - INE2 = - INE3 = 0 V DC AV = 0 dB FB2 = FB3 = 2.25 V FB2 = FB3 = 2.25 V - 14 0.99 - 250 60 3.2 150 1.218 - 250 60 3.2 150 - 10 1.00 - 63 100 1.5* 3.4 40 -2 250 1.230 - 63 100 1.5* 3.4 40 -2 250 -6 1.01 200 -1 1.242 200 -1 A V nA dB MHz V mV mA A V nA dB MHz V mV mA A Threshold voltage Input bias current Voltage gain Error Amp Block (CH1) [Error Amp1] Frequency band width Output voltage VTH IB AV BW VOH VOL ISINK VTH IB AV BW VOH VOL ISINK Output source current ISOURCE Output sink current Threshold voltage Input bias current Error Amp Block (CH2, CH3) [Error Amp2, Error Amp3] Voltage gain Frequency band width Output voltage Output source current ISOURCE Output sink current * : Standard design value (Continued) 6 MB39A112 (Continued) SymPin No. bol VT0 VT100 VH ISOURC E (VCC = VCCO = 12 V, Ta = + 25 C) Parameter Conditions Value Min 1.9 VCCO - 5.5 Typ 2.0 2.5 VCCO - 5.0 - 150* Max 2.6 VCCO - 4.5 Unit V V V PWM Comparator Threshold voltage Block [PWM Comp.] Bias Voltage Block [VH] Output voltage Output source current 17 to 19 Duty cycle = 0 % 17 to 19 Duty cycle = 100 % 16 Duty 5 % 17 to 19 OUT1 = OUT2 = OUT3 = 7 V Duty 5 % 17 to 19 OUT1 = OUT2 = OUT3 = 12 V 17 to 19 17 to 19 4 OUT1 = OUT2 = OUT3 = - 15 mA OUT1 = OUT2 = OUT3 = 15 mA mA Output Block [Drive] Output sink current ISINK 150* 19.5 15 9 mA mA ROH Output ON resistor ROL General Power supply current ICC 13 10 6 * : Standard design value 7 MB39A112 s TYPICAL CHARCTERISTICS Power Supply Current vs. Power Supply Voltage Power supply current ICC (mA) 10 8 6 4 2 0 0 5 10 15 20 25 Ta = +25 C RT = OPEN Power supply voltage VCC (V) Error Amp (ERR1) Threshold Voltage vs. Ambient Temperature Threshold voltage VTH (%) Threshold voltage VTH (%) 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -40 -20 0 20 40 60 80 100 VCC = 12 V FB1 = 0 mA Error Amp (ERR2, ERR3) Threshold Voltage vs. Ambient Temperature 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -40 -20 0 20 40 60 80 100 VCC = 12 V FB2(3) = 0 mA Ambient temperature Ta ( C) Triangular Wave Oscillation Frequency vs. Timing Resistor Triangular wave oscillation frequency fosc (kHz) 10000 Ambient temperature Ta ( C) Triangular Wave Oscillation Frequency vs. Timing Capacitor Triangular wave oscillation frequency fosc (kHz) 10000 Ta = +25 C VCC = 12 V Ta = +25 C VCC = 12 V CT = 22 pF CT = 100 pF CT = 1000 pF CT = 390 pF 1000 1000 RT = 22 k 100 RT = 4.7 k RT = 10 k 100 10 1 10 100 1000 10 10 100 1000 10000 Timing resistor RT (k) Timing capacitor CT (pF) (Continued) 8 MB39A112 Triangular Wave Upper/Lower Limit Voltage vs. Triangular Wave Oscillation Frequency Triangular wave upper/lower limit voltage VCT (V) 2.8 2.6 2.4 2.2 Lower limit Triangular Wave Upper/Lower Limit Voltage vs. Ambient Temperature Triangular wave upper/lower limit voltage VCT (V) 2.8 2.6 2.4 2.2 Lower limit Ta = +25 C VCC = 12 V CT = 100 pF Upper limit VCC = 12 V RT = 10 k CT = 100 pF Upper limit 2.0 1.8 2.0 1.8 -40 -20 0 500 1000 1500 2000 2500 3000 0 20 40 60 80 100 Triangular wave oscillation frequency fosc (kHz) Triangular Wave Oscillation Frequency vs. Ambient Temperature Ambient temperature Ta ( C) Triangular Wave Oscillation Frequency vs. Power Supply Voltage Triangular wave oscillation frequency fosc (kHz) 1400 1350 1300 1250 1200 1150 1100 1050 1000 -40 -20 0 20 40 Triangular wave oscillation frequency fosc (kHz) VCC = 12 V RT = 10 k CT = 100 pF 1400 1350 1300 1250 1200 1150 1100 1050 1000 0 5 10 15 Ta = +25 C RT = 10 k CT = 100 pF 60 80 100 20 25 30 Ambient temperature Ta ( C) Power supply voltage VCC (V) (Continued) 9 MB39A112 (Continued) Error Amp (CH1) Gain, Phase vs. Frequency 40 AV 30 20 Ta = +25 C VCC = 12 V 180 10 k 1 F + IN 10 k 3.5 V 2.4 k 1 + + 1.0 V 240 k Phase (deg) 90 Gain AV (dB) 10 0 -10 -20 -30 -40 100 1k 10 k 100 k 1M -180 10 M -90 0 2 - 3 OUT Error Amp1 Frequency f (Hz) Error Amp (CH2, CH3) Gain, Phase vs. Frequency 40 AV 30 20 90 Ta = +25 C VCC = 12 V 180 10 k 1 F + 240 k Gain AV (dB) 10 0 -10 -20 -30 -40 100 1k 10 k 100 k 1M -180 10 M -90 0 Phase (deg) IN 10 k 2.4 k 9 (12) 10 (11) - + + 1.23 V 8 OUT (13) Error Amp2 (Error Amp3) 3.5 V Frequency f (Hz) Maximum Power Dissipation vs. Ambient Temperature Maximum power dissipation PD (mW) 1400 1300 1280 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 -40 -20 0 20 40 60 80 100 Ambient temperature Ta ( C) 10 MB39A112 s FUNCTION 1. DC/DC Converter Function (1) Triangular Wave Oscillator Block (OSC) The triangular wave oscillator incorporates a timing capacitor and a timing resistor connected respectively to the CT terminl (pin 6) and RT terminl (pin 5) to generate triangular oscillation waveform amplitude of 2.0 V to 2.5 V. The triangular waveforms are input to the PWM comparator in the IC. (2) Error Amplifier Block (Error Amp1, Error Amp2, Error Amp3) The error amplifier detects the DC/DC converter output voltage and outputs PWM control signals. In addition, an arbitrary loop gain can be set by connecting a feedback resistor and capacitor from the output terminal to inverted input terminal of the error amplifier, enabling stable phase compensation to the system. Also, it is possible to prevent rush current at power supply start-up by connecting a soft-start capacitor with the CS1 terminl (pin 1) , CS2 terminl (pin10) and CS3 terminl (pin 11) which are 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. (3) PWM Comparator Block (PWM Comp.) The PWM comparator is a voltage-to-pulse width modulator that controls the output duty depending on the input/ output voltage. The comparator keeps output transistor on while the error amplifier output voltage remain higher than the triangular wave voltage. (4) Output Block The output blobk is in the totem pole configulation, capable of driving an external P-channel MOS FET. (5) Bias Voltage Block (VH) This bias voltage circuit outputs VCC - 5 V (Typ) as minimum potential of the output circuit. 2. Protective Function (1) Timer Latch Short-circuit Protection Circuit (SCP) Each channel has a short-circuit detection comparator (SCP Comp.) which constantly compares the error Amp. output level to the reference voltage. While DC/DC converter load conditions are stable on all channels, the short-circuit detection comparator output remains at "L", and the CSCP terminal is held at "L" level. If the load condition on a channel changes rapidly due to a short-circuit of the load, causing the output voltage to drop, the output of the short-circuit detection comparator on that channel goes to "H" level. This causes the external short-circuit protection capacitor CSCP connected to the CSCP terminal (pin 14) to be charged. When the capacitor CSCP is charged to the threshold voltage (VTH = 0.72 V) , the latch is set and the external : FET is turned off (dead time is set to 100 %) . At this point, the latch input is closed and the CSCP terminal is held at "L" level. The latch applied by the timer-latch short-circuit protection circuit can be reset by recycling the power supply (VCC) (See "s SETTING TIME CONSTANT FOR TIMER-LATCH SHORT-CIRCUIT PROTECTION CIRCUIT") . 11 MB39A112 (2) Undervoltage Lockout Protection Circuit Block (UVLO) The transient state or a momentary decrease in supply voltage, which occurs when the power supply is turned on, may cause the IC to malfunction, resulting in breakdown or degradation of the system. To prevent such malfunctions, under voltage lockout protection circuit detects a decrease in internal reference voltage with respect to the power supply voltage, turns off the output transistor, and sets the dead time to 100% while holding the CSCP terminal (pin 14) at the "L" level. The circuit restores the output transistor to normal when the supply voltage reaches the threshold voltage of the undervoltage lockout protection circuit. (3) Protection Circuit Operating Function Table This table refers to output condition when each protection circuit is operating. CH1 CH2 Operating circuit OUT1 OUT2 Short-circuit protection circuit Under-voltage lockout circuit H H H H CH3 OUT3 H H The latch can be reset as follows after the short-circuit protection circuit is actuated. Recycling VCC resets the latch whenever the short-circuit protection circuit has been actuated. 12 MB39A112 s SETTING THE OUTPUT VOLTAGE * CH1 VO R1 Error Amp 2 -INE1 R2 - + + 1.00 V CS1 1 VO (V) = 1.00 R2 (R1 + R2) * CH2, CH3 VO R1 (-INE3) -INE2 R2 (CS3) CS2 12 9 - + + Error Amp VO (V) = 1.23 R2 (R1 + R2) 1.23 V 11 10 s SETTING THE TRIANGULAR OSCILLATION FREQUENCY The triangular oscillation frequency is determined by the timing capacitor (CT) connected to the CT terminal (pin 6) and the timing resistor (RT) connected to the RT terminal (pin 5) . Triangular oscillation frequency : fosc fosc (kHz)= : 1200000 CT (pF) * RT (k) 13 MB39A112 s 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, CS2 and CS3) to the CS1 terminal (pin 1) for channel 1, CS2 terminal (pin 10) for channel 2 and CS3 terminal (pin 11) for channel 3 respectively. Setting each control terminal (CTLX) from "H" to "L" starts charging the external soft-start capacitors (CS1, CS2 and CS3) connected to the CS1, CS2 and CS3 terminal at about 10 A. The DC/DC converter output voltage rises in proportion to the CS terminal voltage. Also, soft-start time is obtained by the following formulas. Soft-start time : ts (time to output 100%) CH1 CH2 CH3 * Soft-start circuit -INE1 (-INE2) (-INE3) VO CS1 (CS2) (CS3) VREF 10 A - + + Error Amp : ts1[s] = 0.100 x CS1[F] : : ts2[s] = 0.123 x CS2[F] : : ts3[s] = 0.123 x CS3[F] : L priority CH1 ON/OFF signal (L : ON, H : OFF) CTLX FB1 (FB2) (FB3) 1.23 V /1.0 V H : at SCP SCP UVLO H: UVLO release * Soft-start operation = 3.4 V : = 1.23 V/ : 1.00 V =0V : CS terminal voltage Error Amp. reference voltage t Soft-start time ts H CTLX signal L t 14 MB39A112 s TREATMENT WITHOUT USING CS TERMINAL When not using the soft-start function, open the CS1 terminal (pin 1) , CS2 terminal (pin 10) and CS3 terminal (pin 11) . * Without setting soft-start tme "Open" 1 CS1 "Open" 10 CS2 "Open" 11 CS3 15 MB39A112 s 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. 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 14) is held at "L" level. If the load condition on a channel changes rapidly due to a short-circuit of the load, causing the output voltage to drop, the output of the short-circuit detection comparator goes to "H" level. This causes the extemal shortcircuit protection capacitor CSCP connected to the CSCP terminal to be charged at 1 A. Short-circuit detection time : tcscp tcscp[s] = 0.72 x CSCP [F] : When the capacitor CSCP is charged to the threshold voltage (VTH = 0.72 V) , the latch is set and the external FET : is turned off (dead time is set to 100 %) . At this time, the latch input is closed and the CSCP terminal (pin 14) is held at "L" level. If any of CH1 to CH3 detects a short circuit, all the channels are stopped. * Timer-latch short-circuit protection circuit VO R1 -INE1 (-INE2) (-INE3) VREF R2 10 A CS1 (CS2) (CS3) - + + Error Amp 1.23 V /1.0 V FB1 (FB2) (FB3) SCP Comp. + + + - 2.7 V [SCP] 1 A H: UVLO release CSCP 14 VCC S R UVLO Latch H: at SCP 16 MB39A112 s TREATMENT WITHOUT USING CSCP TERMINAL When not using the timer-latch short-circuit protection circuit, connect the CSCP terminal (pin 14) to GND with the shortest distance. * Treatment without using CSCP terminal 14 CSCP 7 GND 17 MB39A112 s I/O EQUIVALENT CIRCUIT < VCC 4 VREF (3.5 V) < VCC < VCC VREF (3.5 V) ESD protection element ESD protection element 2 k 14 CSCP ESD protection element VREF (3.5 V) 1.2 V + - 5 RT GND CT 6 GND 7 GND < VCC VREF (3.5 V) CSX VCC VREF (3.5 V) -INE1 2 < CS1 1.00 V 3 FB1 GND GND < VCC VREF (3.5 V) CSX 1.23 V < VCC FBX FBX CT GND GND < VCC VCCO VCCO 20 < |
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