FUJITSU SEMICONDUCTOR DATA SHEET DS04-27227-1E ASSP For Power Management Applications 1-channel DC/DC Converter IC with Synchronous Rectifier MB3885 ■ DESCRIPTION The MB3885 is a 1-channel DC/DC converter IC using pulse width modulation (PWM) and synchronous rectification, designed for down conversion applications. This device is a power supply with high output drive capacity. Synchronous rectification also provides for high efficiency. In addition, a 5 V regulator is built in to reduce the number of system components. The result is an ideal built-in power supply for driving products with high speed CPU’s such as home TV game devices and notebook PC’s. ■ FEATURES • • • • • • • Synchronous rectification for high efficiency Supply voltage range : 5.5 V to 18 V Built-in high-precision reference voltage circuit : 2.5 V ± 1% Error Amp. threshold voltage : 1.25 V ± 1% (0 °C to 85 °C) Oscillator frequency range : 10 kHz to 500 kHz Built-in soft start circuit with error Amp. input control Totem pole type output for N-ch MOSFET ■ PACKAGE 20-pin Plastic SSOP (FPT-20P-M03) MB3885 ■ PIN ASSIGNMENTS (TOP VIEW) N.C. : 1 20 : N.C. N.C. : 2 19 : N.C. CSCP : 3 18 : VREF CT : 4 17 : SGND RT : 5 16 : PGND CS : 6 15 : OUT2 FB : 7 14 : VS −INE : 8 13 : OUT1 +INE : 9 12 : CB VCC : 10 11 : VB (FPT-20P-M03) 2 MB3885 ■ PIN DESCRIPTIONS Pin No. Symbol I/O Description 1 N.C. No connection 2 N.C. No connection 3 CSCP Timer latch short protection capacitor connection terminal 4 CT Triangular wave oscillator frequency setting capacitor connection terminal 5 RT Triangular wave oscillator frequency setting resistor connection terminal 6 CS Soft start capacitor connection terminal (Also used as output control) 7 FB O Error Amp. output terminal 8 −INE I Error Amp. inverted input terminal 9 +INC I Overvoltage comparator non-inverted input terminal 10 VCC Reference voltage, control circuit power supply terminal 11 VB O Output circuit bias output terminal 12 CB Output bootstrap terminal Insert a capacitor between the CB and VS terminals, to bootstrap the IC internal output transistor. 13 OUT1 O Totem pole output terminal (External main side FET gate drive) 14 VS External main side FET source connection terminal 15 OUT2 O Totem pole output terminal. (External synchronous rectifier side FET gate drive) 16 PGND Ground terminal 17 SGND Ground terminal 18 VREF O Reference voltage output terminal 19 N.C. No connection 20 N.C. No connection 3 MB3885 ■ BLOCK DIAGRAM VCC 10 5 V Reg. FB 7 11 VB 10 µA 12 CB Error Amp. −INE 8 PWM Comp.1 − + + CS 6 + + − DTC 1.25 V OVP Comp. 13 OUT1 PWM Comp.2 + +INC 9 Drive1 14 VS + − VCC 1.47 V − Latch R Drive2 15 OUT2 16 PGND SQ SCP Comp. 1 µA CSCP 3 1.9 V − + 1.3 V 2.1 V bias S R Latch UVLO OSC 4 CT 4 5 RT bias VCC Ref (2.5 V) Power 18 VREF 17 SGND MB3885 ■ ABSOLUTE MAXIMUM RATINGS Parameter Symbol Conditions Supply voltage VCC Boot voltage VCB Rating Unit Min. Max. 20 V 25 V 120 mA CB terminal Output current IO Peak output current IOP Duty ≤ 5% (t = 1 / fOSC × Duty) 800 mA Power dissipation PD Ta ≤ +25 °C 555* mW −55 +125 °C Storage temperature Tstg * : The package is mounted on the dual-sided epoxy board (10cm × 10cm). 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. 5 MB3885 ■ RECOMMENDED OPERATING CONDITIONS Parameter Symbol Conditions Supply voltage VCC Boot voltage Value Unit Min. Typ. Max. 5.5 12 18 V VCB CB terminal 23 V Reference voltage output current IOR VREF terminal −1 0 mA Bias output current IOB VB terminal −1 0 mA VIN −INE terminal 0 VCC − 1.8 V VINC +INC terminal 0 VCC V −100 100 mA −700 700 mA Input voltage Output current IO Peak output current IOP Oscillator frequency fOSC 10 200 500 kHz Timing resistor RT 6.8 10 12 kΩ Timing capacitor CT 150 470 15000 pF Boot capacitor CB 0.1 1.0 µF Duty ≤ 5% (t = 1 / fosc × Duty) Reference voltage output capacitor CREF VREF terminal 0.1 1.0 µF Bias output capacitor CVB VB terminal 1.0 4.7 10 µF Soft start capacitor CS 0.1 1 µF CSCP 0.01 0.1 µF Ta −30 +25 +85 °C Short detection capacitor Operating ambient temperature 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. 6 MB3885 ■ ELECTRICAL CHARACTERISTICS (VCC = 12 V, VB = 0 mA, VREF = 0 mA, Ta = +25 °C) Parameter 4. Soft Start Block [CS] 5. Short Detection Comparator Block [SCP] 6. Triangular Wave Oscillator Block [OSC] 7. Error Amp Block [Error Amp.] Value Unit Min. Typ. Max. 2.475 2.500 2.525 V 18 Ta = +25 °C ∆VREF/ VREF 18 Ta = 0 °C to +85 °C 0.5* % Line 18 VCC = 5.5 V to 18 V 1 10 mV Load 18 VREF = 0 mA to −1 mA 3 10 mV Short output current Ios 18 VREF = 2 V −28 −14 −7 mA Output voltage VB 11 4.95 5.05 5.15 V Threshold voltage VTH 10 2.6 2.9 3.2 V Hysteresis width VH 10 0.2* V VRST 10 1.7 2.1 2.5 V Charge current ICS 6 −14 −10 −6 µA Threshold voltage VTH 3 0.63 0.68 0.73 V Input source current ICSCP 3 −1.4 −1.0 −0.6 µA Short detection time tSCP 3 CSCP = 0.01 µF 4.5 6.8 12.2 ms Oscillator frequency fOSC 4 RT = 10 kΩ, CT = 470 pF 170 190 210 kHz ∆fOSC/ fOSC 4 Ta = 0 °C to +85 °C 1* % VTH1 8 FB = 1.6 V, Ta = +25 °C 1.241 1.2500 1.259 V VTH2 8 FB = 1.6 V, Ta = 0 °C to +85 °C 1.2375 1.2500 1.2625 V Input bias current IB 8 −INE = 0 V −200 −20 nA Voltage gain AV 7 DC 60 100 dB 1. Reference Input stability Voltage Block Load stability [Ref] 3. Undervoltage Lockout Circuit Block [UVLO] Conditions VREF Output voltage 2. Bias Voltage Block [VB] Symbol Pin No. Reset voltage Frequency temperature variation rate Threshold voltage VCC = * : Standard design value (Continued) 7 MB3885 (VCC = 12 V, VB = 0 mA, VREF = 0 mA, Ta = +25 °C) Parameter Frequency band width 7. Error Amp Block [Error Amp.] AV = 0 dB Value Unit Min. Typ. Max. 800* kHz 7 VFBH 7 2.2 2.5 V VFBL 7 0.8 1.0 V ISOURCE 7 FB = 1.6 V −100 −45 µA ISINK 7 FB = 1.6 V 1.5 9.0 mA VTL 7 Duty cycle = 0% 1.2 1.3 V VTH 7 Duty cycle = Dtr 1.81 2.0 V Dtr 13 RT = 10 kΩ, CT = 470 pF 85 90 95 % ISOURCE1 13 Duty ≤ 5% (t = 1 / fOSC × Duty) −700* mA ISINK1 13 Duty ≤ 5% (t = 1 / fOSC × Duty) 900* mA VOH1 13 OUT1 = −100 mA, CB = 17 V, VS = 12 V CB − 2.5 CB − 0.9 V VOL1 13 OUT1 = 100 mA, CB = 17 V, VS = 12 V VS + 0.9 VS + 1.4 V Output current ISOURCE2 (synchronous rectifier side) ISINK2 15 Duty ≤ 5% (t = 1 / fOSC × Duty) −750* mA 15 Duty ≤ 5% (t = 1 / fOSC × Duty) 900* mA Output voltage (synchronous rectifier side) VOH2 15 OUT2 = −100 mA 2.5 4.1 V VOL2 15 OUT2 = 100 mA 1.0 1.4 V Diode voltage VD 12 VB = 10 mA 0.9 1.1 V Output voltage Output source current 8. PWM Comparator Threshold Block voltage [PWM Comp.1, PWM Comp.2] Maximum duty cycle Output current (main side) Output voltage (main side) 10. Output Block [Drive] Conditions BW Output sink current 9. Dead time Adjustment Block [DTC] Symbol Pin No. * : Standard design value (Continued) 8 MB3885 (Continued) (VCC = 12 V, VB = 0 mA, VREF = 0 mA, Ta = +25 °C) Parameter Symbol Pin No. tD1 10. Output Block [Drive] 13, 15 Dead time tD2 11. Overvoltage Detection Comparator Block [OVP] 12. General Conditions Value Unit Min. Typ. Max. RT = 10 kΩ, CT = 470 pF OUT1 = OUT2 = OPEN, VS = 0 V OUT2 : − OUT1 : 100 200 ns RT = 10 kΩ, CT = 470 pF OUT1 = OUT2 = OPEN, VS = 0 V OUT1 : − OUT2 : 100 250 ns Threshold voltage VTH 9 +INC = 1.44 1.47 1.50 V Input bias current IB 9 +INC = 0 V −200 −30 nA Power supply current ICC 10 6.5 9.8 mA 9 MB3885 ■ TYPICAL CHARACTERISTICS Reference Voltage vs. Supply Voltage Supply Current vs. Supply Voltage 5 10 Reference voltage VREF (V) Supply current ICC (mA) Ta = +25 °C 8 6 4 2 Ta = +25 °C VREF = 0 mA 4 3 2 1 0 0 0 5 10 15 Supply voltage VCC (V) 0 20 5 10 15 Supply voltage VCC (V) 20 Reference Voltage vs. Ambient Temperature Reference voltage ∆VREF (%) 2.0 VCC = 12 V VREF = 0 mA 1.5 1.0 0.5 0.0 −0.5 −1.0 −1.5 −2.0 −40 −20 0 20 40 60 80 100 Triangular Wave Upper/Lower Limit Voltage vs. Triangular Wave Oscillator Frequency 2.5 Ta = +25 °C VCC = 12 V CTL = 5 V 2.0 Upper limit 1.5 1.0 0.5 1k Lower limit 10 k 100 k 1M Triangular wave oscillator frequency fosc (Hz) Triangular wave upper/lower limit voltage VCT (V) Triangular wave upper/lower limit voltage VCT (V) Ambient temperature Ta (°C) Triangular Wave Upper/Lower Limit Voltage vs. Ambient Temperature 2.5 VCC = 12 V RT = 10 kΩ CT = 470 pF 2.0 Upper limit 1.5 Lower limit 1.0 0.5 −40 −20 0 20 40 60 80 100 Ambient temperature Ta (°C) (Continued) 10 MB3885 Triangular Wave Oscillator Frequency vs. Timing Resistor Triangular wave frequency fOSC (Hz) 10 M Ta = +25 °C VCC = 12 V CTL = 5 V RT = 10 kΩ 1M 100 k 10 k 1k 10 100 1000 10000 10 M Ta = +25 °C VCC = 12 V CTL = 5 V 1M CTL = 150 pF 100 k CTL = 470 pF 10 k CTL = 15000 pF 1k 100 1k 100000 10 k Timing resistor RT (Ω) Triangular Wave Oscillator Frequency vs. Supply Voltage Triangular Wave Oscillator Frequency vs. Ambient Temperature Triangular wave frequency fOSC (Hz) Timing capacitor CT (pF) 250 Ta = +25 °C RT = 10 kΩ CT = 470 pF 240 230 220 210 200 190 180 170 160 150 0 5 10 15 Supply voltage VCC (V) 250 VCC = 12 V RT = 10 kΩ CT = 470 pF 240 230 220 210 200 190 180 170 160 150 −40 20 100 k −20 0 20 40 60 Ambient temperature Ta (°C) 80 100 Error Amp Gain, Phase vs. Frequency φ 20 0 AV −20 180 90 0 −90 VCC = 12 V Phase φ (deg.) Ta = +25 °C 40 Gain AV (dB) Triangular wave frequency fOSC (Hz) Triangular wave frequency fOSC (Hz) Triangular Wave Oscillator Frequency vs. Timing Capacitor 240 kΩ 4.7 kΩ − + 2.4 kΩ 8 6 IN 10 µF 4.7 kΩ 1.5 V −40 1k − + + 1.25 V 7 OUT Error Amp. −180 10 k 100 k 1M Frequency f (Hz) 10 M (Continued) 11 MB3885 (Continued) Power dissipation PD (mW) Power Dissipation vs. Ambient Temperature 600 555 500 400 300 200 100 0 −40 12 −20 0 20 40 60 80 Ambient temperature Ta (°C) 100 MB3885 ■ FUNCTION DESCRIPTION 1. DC/DC Converter Function (1) Reference Voltage Block The reference voltage circuit takes the voltage feed from the power supply terminal (pin 10) and generates a temperature compensated reference voltage (2.5 V typ.) , for use as the reference voltage for the power supply control unit. Also, an external load current can be obtained from the power supply at the VREF terminal (pin 18) , up to a maximum of 1 mA. (2) Triangular Wave Oscillator Block A triangular waveform with amplitude 1.3 V to 1.9 V can be generated by connecting a timing capacitor and resistor to the CT terminal (pin 4) and RT terminal (pin 5) , respectively. The triangular oscillator waveform can be input to the IC’s internal PWM comparator, as well as supplied externally from the CT terminal. (3) Error Amp Block (Error Amp.) The error Amp. is an amplifier that detects the output voltage from the DC/DC converter and outputs a PWM control signal. The error Amp. has a broad in-phase input voltage range of 0 to Vcc−1.8 V that can be easily set by the external power supply. In addition, an arbitrary loop gain can be set up by connecting a feedback resistor and capacitor between the error Amp. output pin and inverter input pin, providing stable phase compensation to the system. Also, power-on rush current can be prevented by connecting a soft start capacitor between the error Amp. noninverted input pins CS terminal (pin 6) . The soft start function operates with a stable soft start time that is not dependent on the output load of the DC/DC converter. (4) PWM Comparator Block (PWM Comp.) This is a voltage - pulse width modulator that controls the output duty according to the input voltage. Main side : Turns the output FET on in the intervals in which the error Amp. output voltage is higher than the triangular wave voltage. Synchronous rectifier side : Turns the output FET on in the intervals in which the triangular wave voltage the is lower than error Amp. voltage. (5) Output Block The output block has totem pole configuration on both the main side and synchronous rectifier side, and can drive an external N-ch MOSFET. Also, the high output drive capability (700 mA Max. : duty ≤ 5%) provides high gate-source capacitor, enabling the use of low on-resistor FET devices. 13 MB3885 2. Control Functions Output ON/OFF control is provided by using the CS terminal (pin 6) setting functions. Output On/Off Setting Functions CS terminal voltage level Output state GND OFF Hi-Z ON 3. Protective Functions (1) Timer Latch Short Circuit Protection (SCP) The short circuit protection comparators read the output voltage levels. If the output voltage falls below the short detection voltage, the timer circuit is activated to start charging the external capacitor Cscp connected to the CSCP terminal (pin 3) . When capacitor voltage reaches approximately 0.68 V the output FET turns off, setting the idle interval to 100%. Once the protection circuit is activated, it can be reset by turning the power supply off and on again. (See “Setting the Timer Latch Short Circuit Protector Time Constant.”) (2) Undervoltage Lockout Circuit Block (UVLO) Transient status during normal power-on or momentary drops in supply voltage can cause abnormal operation in an control IC, leading to damage or degradation of system components. The undervoltage lockout circuit prevents such abnormal operations by reading the internal reference voltage level and switching the output FET off, setting the idle interval to 100% and holding the CSCP terminal (pin 3) to “L” level. System operation is restored when the supply voltage rises back about the undervoltage lockout circuit threshold voltage. (3) Overvoltage Protection Block (OVP) The overvoltage protection circuit uses an overvoltage comparator (OVP Comp.) to read the output voltage levels from the DC/DC converter. If the output voltage exceeds the threshold voltage a latch is set, turning off the main side FET. Once the protector circuit is activated, it can be reset by switching the power supply off and on again. 14 MB3885 ■ SETTING THE TIMER LATCH SHORT CIRCUIT PROTECTOR TIME CONSTANT The error Amp. output level constantly compares operation with the short circuit protection comparator as the reference voltage. When the DC/DC comparator load conditions are stable, the short circuit protection comparator output is at “H” level, transistor Q1 is on, and the CSCP terminal (pin 3) is held at input standby voltage (VSTB : = 50 mV) . If load conditions change rapidly, such as during a load short, causing output voltage to drop, the short circuit protection comparator output goes to “L” level. This causes the transistor Q1 to shut off, charging the short circuit protection capacitor Cscp (connected to the CSCP terminal) at 1 µA. Short detection time tscp (s) =: 0.68 × Cscp (µF) When the capacitor Cscp is charted to the threshold voltage (VTH : = 0.68 V) a latch is set, turning the external FET off (setting the idle interval to 100%) . At this time the latch input is closed and the CSCP terminal is held at the input latch voltage (VI : = 50 mV) . 10 µA FB 7 −INE CS − + + 8 Error Amp. Drive 13 OUT1 Drive 15 OUT2 6 1.25 V CS Q2 SCP Comp. 1 µA − + CSCP bias 3 S CSCP 2.1 V R Latch Q1 UVLO Q4 < Timer Latch Short Circuit Protection Circuit > 15 MB3885 ■ PROCESSING WITHOUT USING THE CSCP TERMINAL When the timer latch short circuit protection circuit is not used, the CSCP terminal (pin 3) should be shorted to SGND using the shortest possible connection. 17 SGND CSCP 3 < Operation Without Using the CSCP Terminal > 16 MB3885 ■ SOFT START TIME SETTING The soft start function prevents rush current events when the IC power is turned on, by connecting soft start capacitors (Cs) to the CS terminal (pin 6) . When the IC is activated (Vcc ≥ UVLO threshold voltage) , Q2 is off and the CS terminals begin charging the externally connected soft start capacitors (Cs) at 10 µA. Because the error Amp. output (FB) is determined by the ratio of the lower of the two non-inverted input terminals (1.25 V, CS terminal voltage) to the inverted input terminal voltage (−INE) , the soft start interval (when CS terminal voltage < 1.25 V) FB is determined by the ratio of the −INE terminal voltage and CS terminal voltage. Thus the DC/DC converter output voltage is in proportion to the rise in the CS terminal voltage as the soft start capacitor connected to the CS terminal charges. The soft start time is determined by the following formula. Soft start time (time to output 100%) ts (s) =: 0.125 × Cs (µF) CS terminal voltage 2.3 V Error. amp block comparison voltage to −INE voltage 1.25 V 0V Soft start time ts 17 MB3885 VREF 10 µA FB 7 −INE 8 CS 10 µA − + + Error Amp. 6 1.25 V CS Q2 UVLO < Soft Start Block 18 > MB3885 ■ PROCESSING WITHOUT USING THE CS TERMINALS When the soft start function is not used, the CS terminal (pin 6) should be left open. "Open" CS < Operation Without Soft Start Setting > ■ OSCILLATOR FREQUENCY SETTING The oscillator frequency can be set by connecting a timing capacitor (CT) to the CT terminal (pin 4) and a timing resistor (RT) to the RT terminal (pin 5) . Oscillator frequency 893000 fosc (kHz) =: CT (pF) •RT (kΩ) ■ OUTPUT VOLTAGE SETTING VO FB 7 VO = R1 −INE 8 R2 CS − + + Error Amp. 1.25 V R2 (R1 + R2) 6 1.25 V 19 MB3885 ■ OVERVOLTAGE PROTECTION CIRCUIT VOTAGE SETTING Overvoltage conditions in the DC/DC converter output voltage can be detected by connecting external resistance from the DC/DC converter output voltage to the +INC terminal (pin 9) on the respective overvoltage protection comparator circuits (OVP comp.) . When the output voltage of the DC/DC converter rises above the detection voltage, the overvoltage protection comparator (OVP Comp.) output goes to “H” level, setting a latch and shutting off. Detection voltage VOVP (V) =: 1.47 × (R3 + R4) /R4 Once the protection circuit has been activated, it can be reset by lowering the VCC voltage below the reset voltage (1.7 V Min.) . VO VCC R3 +INC1 R4 9 + R S − 1.47 V 20 OVP Comp. Q MB3885 ■ PRECAUTIONS RELATED TO SUPPLY VOLTAGE RANGE Although the supply voltage range listed under recommended operating requirements is 5.5V-18V, generation of heat limits the maximum operating supply voltage since the IC’s internal loss varies with the frequency of oscillation and FET’s total gate charge. When using the MB 3885 in an application, caution must be taken in relation to supply voltage range. As shown below, IB (average current) can be determined from the total gate charge Qg1, Qg2, charged from the gate capacitance (Ciss1, Ciss2, Crss1, Crss2) of the external FET Q1, Q2, by the following formula. IB (A) = I1 + I2 = Ibias1 × T1 Qg1 T2 Qg2 + + Ibias2 × + T T T T (Ibias1 = Ibias2 =: 2 mA) Because IC current consumption other than IB is 6.5 mA, power consumption can be determined from the following formula. Power consumption : Pc Pc (W) =: 0.0065 × VCC + VCC × IB − 1 / 2 × VB × IB 21 MB3885 Vin VCC 10 IB 5V 11 12 VB CVB A CB L1 Q1 I1 Drive 1 13 14 I2 OUT1 VO1 Crss2 Crss1 Q2 Ciss1 VS Ciss2 Drive 2 15 16 OUT2 PGND T VOUT1 VOUT2 I1 Bias current Ibias1 2 mA T1 I2 Bias current Ibias2 2 mA T2 t Using the above formulas to determine power consumption, settings should be made with reference to the “Power Consumption vs. Input Voltage” on the following page, as well as the “Power dissipation vs. Ambient Temperature.” 22 MB3885 Power Consumption vs. Input Voltage (Qg Parameters) Power consumption PC (W) 1.00 0.90 0.80 Ta = +25 °C fOSC = 200 kHz SW1 = OFF 0.70 0.60 Qg1 = Qg2 = 70 nC 0.50 Qg1 = Qg2 = 50 nC 0.40 Qg1 = Qg2 = 30 nC Qg1 = Qg2 = 20 nC Qg1 = Qg2 = 10 nC 0.30 0.20 0.10 0.00 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Input voltage Vin (V) Power Consumption vs. Input Voltage (fosc Parameters) Power consumption PC (W) 1.00 0.90 0.80 Ta = +25 °C Qg1 = Qg2 = 20 nC SW1 = OFF 0.70 0.60 0.50 fOSC = 500 kHz 0.40 fOSC = 300 kHz fOSC = 200 kHz fOSC = 100 kHz fOSC = 10 kHz 0.30 0.20 0.10 0.00 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Input voltage Vin (V) 23 24 VCC 10 VB 5 V Reg. 11 D2 FB A Output On/Off signal SW1 C3 0.022 µF R1 R6 2 kΩ 2.7 kΩ −INE 10 µA +INC 6.2 kΩ 1.25 V 9 R5 10 kΩ − − 1 µA + VS 14 15 Drive2 C5 0.01 µF 3 1.9 V 1.3 V bias S R Latch L1 2.7 µH C1 + 22 µF bias UVLO Ref (2.5 V) Power OSC 4 CT C6 470 pF VCC 5 RT 18 17 VREF SGND R7 10 kΩ C7 0.1 µF C10 + C2 0.1 µF Q2 OUT2 PGND 16 2.1 V CSCP Vo (2 V) 13 Drive1 + − A OUT1 PWM Comp.2 + Latch VCC R SQ 1.47 V C9 0.1 µF Q1 + + − DTC OVP Comp. SCP Comp. C8 CB 4.7 µF PWM Comp.1 − + + R2 3.3 kΩ 0.1 µF R4 12 Error Amp. 8 CS 6 C4 R3 10 kΩ 7 D1 68 µF ×3 C11 2.2 µF MB3885 ■ APPLICATION CIRCUIT C12 0.1 µF Vin MB3885 ■ COMPONENT LIST COMPONENT ITEM SPECIFICATION VENDOR PARTS No. Q1, Q2 FET VDS = 30 V, Qg = 23 nC (Max.) IR IRF7811 D1 D2 Diode Diode VF = 0.35 V (Max.) , at IF = 1 A VF = 0.3 V (Max.) , at IF = 10 mA ROHM ROHM RB051L-40 RB495D L1 Coil 2.7 µH 12 A, 4.5 mΩ TDK RLF12545T -2R7N8R7 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 OS Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser Ceramics Condenser Electrolytic Condenser Ceramics Condenser Ceramics Condenser 22 µF 0.1 µF 0.022 µF 0.1 µF 0.01 µF 470 pF 0.1 µF 4.7 µF 0.1 µF 68 µF 2.2 µF 0.1 µF 25 V 25 V 25 V 25 V 10 V 50 V 25 V 10 V 25 V 6.3 V 6.3 V 25 V R1 R2 R3 R4 R5 R6 R7 Resistor Resistor Resistor Resistor Resistor Resistor Resistor 2 kΩ 3.3 kΩ 10 kΩ 6.2 kΩ 10 kΩ 2.7 kΩ 10 kΩ 1/4 W 1/4 W 1/4 W 1/4 W 1/4 W 1/4 W 1/4 W Notes : IR : International Rectifier Corp. ROHM : Rohm, Ltd. TDK : TDK, Ltd. 25 MB3885 ■ REFERENCE DATA Conversion Efficiency vs. Load Current Characteristics 100 Ta = +25 °C 2 V output SW1 = OFF Conversion efficiency η (%) 95 90 Vin = 6 V 85 Vin = 8.5 V Vin = 10 V 80 75 70 0 1 2 3 4 5 6 Load current IL (A) 26 7 8 9 10 MB3885 ■ PRECAUTIONARY INFORMATION • Printed circuit board ground lines should be designed with consideration for common impedance. • • • • • Take sufficient countermeasures should be taken to protect against static electricity. Always place semiconductors in containers that have anti-static provisions, or are conductive. After mounting, PC boards should be placed in conductive bags or containers for storage and handling. Working surfaces, tools, and measurement equipment should be grounded. Persons handling semiconductors should be grounded directly with resistance of 250 kΩ to 1 MΩ. • Do not apply negative voltages. • Application of negative voltage of −0.3 V or greater can create parasitic transistor effects on an LSI device, leading to abnormal operation. ■ ORDERING INFORMATION Part Number MB3885PFV Package Remarks Plastic SSOP 20-pin (FPT-20P-M03) 27 MB3885 ■ PACKAGE DIMENSION 20-pin, Plastic SSOP (FPT-20P-M03) * Dimensions include resin remainder. * 6.50±0.10(.256±.004) 0.17±0.03 (.007±.001) 11 20 * 4.40±0.10 6.40±0.20 (.173±.004) (.252±.008) INDEX Details of "A" part +0.20 1.25 –0.10 +.008 .049 –.004 LEAD No. 1 10 0.65(.026) "A" 0.24±0.08 (.009±.003) 0.10(.004) C (Mounting height) 0.13(.005) M 0~8° 0.50±0.20 (.020±.008) 0.45/0.75 (.018/.030) 0.10±0.10 (Stand off) (.004±.004) 0.25(.010) 1999 FUJITSU LIMITED F20012S-3C-5 Dimensions in mm (inches) . 28 MB3885 FUJITSU LIMITED For further information please contact: Japan FUJITSU LIMITED Corporate Global Business Support Division Electronic Devices Shinjuku Dai-Ichi Seimei Bldg. 7-1, Nishishinjuku 2-chome, Shinjuku-ku, Tokyo 163-0721, Japan Tel: +81-3-5322-3347 Fax: +81-3-5322-3386 http://edevice.fujitsu.com/ North and South America FUJITSU MICROELECTRONICS, INC. 3545 North First Street, San Jose, CA 95134-1804, U.S.A. Tel: +1-408-922-9000 Fax: +1-408-922-9179 Customer Response Center Mon. - Fri.: 7 am - 5 pm (PST) Tel: +1-800-866-8608 Fax: +1-408-922-9179 http://www.fujitsumicro.com/ Europe FUJITSU MICROELECTRONICS EUROPE GmbH Am Siebenstein 6-10, D-63303 Dreieich-Buchschlag, Germany Tel: +49-6103-690-0 Fax: +49-6103-690-122 http://www.fujitsu-fme.com/ Asia Pacific FUJITSU MICROELECTRONICS ASIA PTE. LTD. #05-08, 151 Lorong Chuan, New Tech Park, Singapore 556741 Tel: +65-281-0770 Fax: +65-281-0220 http://www.fmap.com.sg/ Korea FUJITSU MICROELECTRONICS KOREA LTD. 1702 KOSMO TOWER, 1002 Daechi-Dong, Kangnam-Gu,Seoul 135-280 Korea Tel: +82-2-3484-7100 Fax: +82-2-3484-7111 F0011 FUJITSU LIMITED Printed in Japan 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. 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