FUJITSU SEMICONDUCTOR DATA SHEET DS04-27203-6E ASSP Switching Regulator Controller MB3778 ■ DESCRIPTION The MB3778 is a dual switching regulator control IC. It has a two-channel basic circuit that controls PWM system switching regulator power. Complete synchronization is achieved by using the same oscillator output wave. This IC can accept any two of the following types of output voltage: step-down, step-up, or voltage inversion (inverting voltage can be output to only one circuit). The MB3778’s low power consumption makes it ideal for use in portable equipment. ■ FEATURES • • • • • • • • Wide input voltage range : 3.6 V to 18 V Low current consumption : 1.7 mA typ. operation, 10 µA max. stand-by Wide oscillation frequency range:1 kHz to 500 kHz Built-in timer latch short-circuit protection circuit Built-in under-voltage lockout circuit Built-in 2.46 V reference voltage circuit : 1.23 V output can be obtained from RT terminal Variable dead-time provides control over total range Built-in stand-by function: power on/off function ■ PACKAGES 16-pin, Plastic DIP 16-pin, Plastic SSOP 16-pin, Plastic SOP v (DIP-16P-M04) (FPT-16P-M05) (FPT-16P-M06) MB3778 ■ PIN ASSIGNMENT (TOP VIEW) CT 1 16 VREF RT 2 15 SCP +IN1 3 14 CTL −IN1 4 13 −IN2 FB1 5 12 FB2 DTC1 6 11 DTC2 OUT1 7 10 OUT2 E/GND 8 9 (DIP-16P-M04) (FPT-16P-M05) (FPT-16P-M06) 2 VCC MB3778 ■ PIN DESCRIPTION No. Pin Function 1 CT Oscillator timing capacitor terminal (150 pF to 15,000 pF) . 2 RT Oscillator timing resistor terminal (5.1 kΩ to 100 kΩ) . VREF × 1/2 voltage is also available at this pin for error amplifier reference input. 3 +IN1 Error amplifier 1 non-inverted input terminal. 4 −IN1 Error amplifier 1 inverted input terminal. 5 FB1 Error amplifier 1 output terminal. A resistor and a capacitor are connected between this terminal and the −IN1 terminal to adjust gain and frequency. 6 DTC1 OUT1 dead-time control terminal. Dead-time control is adjusted by an external resistive divider connected to the VREF pin. A capacitor connected between this terminal and GND enables soft-start operation. 7 OUT1 Open collector output terminal. Output transistor has common ground independent of signal ground. This output can source or sink up to 50 mA. 8 E/GND Ground terminal. 9 VCC 10 OUT2 Open collector output terminal. Output transistor has common ground independent of signal ground. This output can source or sink up to 50 mA. 11 DTC2 Sets the dead-time of OUT2. The use of this terminal is the same as that of DTC1. Power supply terminal (3.6 to 18 V) 12 FB2 Error amplifier 2 output terminal. Sets the gain and adjusts the frequency when a resistor and a capacitor are connected between this terminal and the −IN2 terminal. Voltage of VREF × 1/2 voltage is internally connected to the non-inverted input of error amplifier 2. Uses error amplifier 2 for positive voltage output. 13 −IN2 Error amplifier 2 inverted input terminal. CTL Power control terminal. The IC is set in the stand-by state when this terminal is set “Low.” Current consumption is 10 µA or lower in the stand-by state. The input can be driven by TTL or CMOS. 15 SCP The time constant setting capacitor connection terminal of the timer latch short-circuit protection circuit. Connects a capacitor between this pin and GND. For details, see “How to set time constant for timer latch short-circuit protection circuit”. 16 VREF 2.46 V reference voltage output terminal which can be obtained up to 1 mA. This pin is used to set the reference input and idle period of the error amplifiers. 14 3 MB3778 ■ BLOCK DIAGRAM 9 14 2 1 1.23 V 2.46 V 16 Reference Voltage 1.9 V Power Supply Control Triangular Oscillator 1.3 V 13 Error Amp 1 + − 7 − + + 2.46 V 3 4 5 12 OUT1 PWM Comp1 − − + − + + S.C.P. Comp OUT2 10 PWM Comp2 2.1 V Error Amp 2 − + 1.23 V 2.46 V 1 µA 15 R S Latch R U. V. L. O. D.T.C. Comp. − − + 8 1.1 V 6 4 11 MB3778 ■ OPERATION DESCRIPTION 1. Reference voltage circuit The reference voltage circuit generates a temperature-compensated reference voltage ( =: 2.46 V) from VCC (pin 9) . The reference voltage is used as an operation power supply for internal circuit. The reference is obtained from the VREF terminal (pin 16). 2. Triangular wave oscillator Triangular waveforms can be generated at any frequency by connecting a timing capacitor and resistor to the CT terminal (pin 1) and to the RT terminal (pin 2) . The amplitude of this waveform is from 1.3 V to 1.9 V. These waveforms are connected to the non-inverting inputs of the PWM comparator and can be output through the CT terminal. 3. Error amplifiers (Error Amp.) The error amplifier detects the output voltage of the switching regulator and outputs PWM control signals.The in-phase input voltage range is from 1.05 V to 1.45 V.The reference voltage obtained by dividing the reference voltage output (recommended value : VREF/2) or the RT terminal voltage (1.23 V) is supplied to the non-inverting input. The VREF/2 voltage is internally connected to non-inverting input of the other error amplifier. Any loop gain can be chosen by connecting the feedback resistor and capacitor to the inverting input terminal from the output terminal of the error amplifier.Stable phase compensation is possible. 4. Timer latch short circuit protection circuit This circuit detects the output levels of each error amplifier. If the output level of one or both of the error amplifiers is 2.1 V or higher, the timer circuit begins charging the externally connected protection enable-capacitor. If the output level of the error amplifier does not drop below the normal voltage range before the capacitor voltage reaches the transistor base-emitter voltage, VBE( =: 0.65 V), the latch circuit turns the output drive transistor off and sets the idle period to 100%. 5. Under voltage lock-out circuit The transition state at power-on or a momentary drops in supply voltage may cause the control IC to malfunction, which may adversely affect or even destroy the system. The under voltage lockout circuit monitors VCC with reference to the internal reference voltage and resets the latch circuit to turn the output drive transistor off. The idle period is set to 100%. It also pulls the SCP terminal (pin 15) “Low”. 6. PWM comparator unit Each PWM comparator has one inverting input and two non-inverting inputs. This voltage-to-pulse-width converter controls the turning on time of the output pulse according to the input voltage. The PWM comparator turns the output drive transistor on while triangular waveforms from the oscillator are lower than the error amplifier output and the DTC terminal voltage. 7. Output drive transistor The output drive transistors have open collector outputs with common source supply and common grounds independent of VCC and signal ground. The output drive transistors for switching can sink or source up to 50 mA. 8. Power control unit The power control terminal (pin 14) controls power on/off modes(the power supply current in stand-by mode is 10 µA or lower). 5 MB3778 ■ ABSOLUTE MAXIMUM RATINGS (See NOTE) (Ta = 25 °C) Parameter Symbol Condition Power Supply Voltage VCC Error Amp. Input Voltage Rating Unit Min. Max. 20 V VIN −0.3 +10 V Control Input Voltage VCTL −0.3 +20 V Collector Output Voltage VOUT 20 V Collector Output Current IOUT 75 Ta ≤ +25 °C (SOP) Ta ≤ +25 °C (SSOP) Power Dissipation Operating Temperature Storage Temperature mA 620* 1 mW 444* 2 mW Ta ≤ +25 °C (DIP) 1000 mW Top −30 +85 °C Tstg −55 +125 °C PD *1: The packages are mounted on the epoxy board (4 cm × 4 cm) *2: 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, temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings. ■ RECOMMENDED OPERATING CONDITIONS Parameter Symbol Value Min. Typ. Max. Unit Power Supply Voltage VCC 3.6 6.0 18 V Error Amp. Input Voltage VIN 1.05 1.45 V Control Input Voltage VCTL 0 18 V Collector Output Voltage VOUT 18 V Collector Output Current IOUT 0.3 50 mA Timing Capacitor CT 150 15000 pF Timing Resistor RT 5.1 100 kΩ Oscillator Frequency fOSC 1 500 kHz Operating Temperature Top −30 25 85 °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. 6 MB3778 ■ ELECTRICAL CHARACTERISTICS (Ta = 25 °C, VCC = 6 V) Parameter Symbol Condition Value Unit Min. Typ. Max. 2.41 2.46 2.51 V Reference Block Output Voltage VREF IOR = −1 mA Output Temp. Stability VRTC Ta = −30 °C to +85 °C −2 ±0.2 2 % Input Stability Line VCC = 3.6 V to 18 V 2 10 mV Load Stability Load IOR = −0.1 mA to −1 mA 1 7.5 mV −30 −10 −3 mA Short Circuit Output Current IOS VREF = 2 V Under Voltage Lockout Protection Block VtH IOR = −0.1 mA 2.72 V VtL IOR = −0.1 mA 2.60 V VHYS IOR = −0.1 mA 80 120 mV VR 1.5 1.9 V Input Thresold Voltage VtPC 0.60 0.65 0.70 V Input Stand by Voltage VSTB No pull up 50 100 mV Input Latch Voltage VIN No pull up 50 100 mV Input Source Current Ibpc −1.4 −1.0 −0.6 µA Comparator Threshold Voltage VtC Pin 5, Pin 12 2.1 V Oscillator Frequency fOSC CT = 330 pF, RT = 15 kΩ 160 200 240 kHz Frequency Deviation fdev CT = 330 pF, RT = 15 kΩ ±5 % Frequency Stability (VCC) fdV VCC = 3.6 V to 18 V ±1 % Frequency Stability (Ta) fdT Ta = −30 °C to +85 °C −4 +4 % 0.2 1 µA Threshold Voltage Hysteresis Width Reset Voltage (VCC) Protection Circuit Block (S.C.P.) Triangular Waveform Oscillator Block Dead-Time Control Block (D.T.C.) Input Bias Current Ibdt Latch Mode Sink Current Idt Vdt = 2.5 V 150 500 µA Latch Input Voltage Vdt Idt = 100 µA 0.3 V 7 MB3778 ■ ELECTRICAL CHARACTERISTICS (Continued) (Ta = 25 °C, VCC = 6 V) Parameter Symbol Condition Value Min. Typ. Max. Unit Error Amp. Block Input Offset Voltage VIO VO = 1.6 V −6 6 mV Input Offset Current IIO VO = 1.6 V −100 100 nA Input Bias Current IB VO = 1.6 V −500 −100 nA VCC = 3.6 V to 18 V 1.05 1.45 V Common Mode Input Voltage Range VICR Voltage Gain AV RNF = 200 kΩ 70 80 dB Frequency Band Width BW AV = 0 dB 1.0 MHz Common Mode Rejection Ratio Max. Output Voltage Width CMRR 60 80 dB VOM+ VREF − 0.3 V VOM− 0.7 0.9 V Output Sink Current IOM+ VO = 1.6 1.0 mA Output Source Current IOM− VO = 1.6 −60 µA Vt100 Duty Cycle = 100% 1.9 2.25 V 1.05 1.3 V PWM Comparator Block Input Threshold Voltage (fOSC = 10 kHz) Vt0 Duty Cycle = 0% On duty Cycle Dtr Vdt = VREF/1.45 55 65 75 % Input Sink Current IIN+ Pin 5, Pin 12 = 1.6 V 1.0 mA Input Source Current IIN− Pin 5, Pin 12 = 1.6 V −60 µA Control Block Input Off Condition VOFF 0.7 V Input On Condition VON 2.1 V Control Terminal Current ICTL VCTL = 10 V 200 400 µA Output Block Output Leak Current Leak VO = 18 V 10 µA Output Saturation Voltage VSAT IO = 50 mA 1.1 1.4 V Stand-by Current ICCS VCTL = 0 V 10 µA Average Supply Current ICCa VCTL = VCC, No Output Load 1.7 2.4 mA All Device Block 8 MB3778 ■ TEST CIRCUIT CTL VCC = 6 V INPUT TEST SW 4.7 kΩ CPE OUTPUT 1 4.7 kΩ OUTPUT 2 16 15 14 13 12 11 10 9 6 7 8 MB3778 1 330 pF 2 3 4 5 15 kΩ TEST INPUT ■ TIMING CHART (Internal Waveform) Triangular waveform oscillator output Short circuit protection comparator Reference 2.1 V 1.9 V input 1.6 V Dead Time, PWM input voltage 1.3 V Error Amp. output PWM comparator output "High" Output Transistor collector waveform "High" S.C.P. Terminal waveform 0.65 V Short circuit protection comparator output "High" "Low" DEAD TIME 100% "Low" 0.05 V tPE "Low" Power “ON” Control Terminal voltage Power “OFF” 2.1 V (VCTL : Min. Value) 0V Power supply voltage 3.6 V (VCC : Min. Value) 0V Protection Enable Time tPE 0.6 × 106 × CPE (µs) 9 MB3778 ■ APPLICATION CIRCUIT • Chopper Type Step Down/inverting VIN (10 V) CTL 820 pF 1 16 2 15 3 14 0.1 µF 8.2 kΩ 56 µH 1.8 kΩ 4.7 kΩ 4.7 kΩ 0.033 µF 4.7 kΩ 150 kΩ 1.8 kΩ 4 13 MB3778 5 12 0.033 µF 220 µF − + 10 kΩ 10 kΩ 6 11 − + 1 µF 150 kΩ + − 7 10 8 9 1 µF 5.6 kΩ 2.4 kΩ 330 Ω 330 Ω 330 Ω 330 Ω 120 µH 120 µH − + − + 220 µF 9.1 kΩ VO− ( −5 V) 10 220 µF GND V O+ ( 5 V) MB3778 • Chopper Type Step Up/Inverting VIN (5 V) CTL 820 pF 1 16 2 15 3 14 0.1 µF 8.2 kΩ 56 µH 1.8 kΩ 4.7 kΩ 4.7 kΩ 0.033 µF 4.7 kΩ 150 kΩ 1.8 kΩ 4 13 MB3778 5 12 0.033 µF 220 µF − + 10 kΩ 10 kΩ 6 11 − + 1 µF 150 kΩ + − 7 10 8 9 1 µF 16 kΩ 4.7 kΩ 330 Ω 3.9 kΩ 330 Ω 120 µH 100 Ω 120 µH 220 µF − + 220 µF + − 9.1 kΩ VO− ( −5 V) GND VO+ ( 5 V) 11 MB3778 • Multi Output Type (Apply Transformer) VIN (10 V) CTL 820 pF 1 16 2 15 3 14 0.1 µF 8.2 kΩ 56 µH 1.8 kΩ 4 13 MB3778 5 12 6 11 7 10 8 9 150 kΩ 220 µF − + 0.033 µF 10 kΩ 1.8 kΩ 220 Ω 4.7 kΩ 1000 pF 5.6 kΩ VO2− ( −12 V) 12 − + − + − + − + 220 µF 220 µF 220 µF 220 µF VO1− ( −5 V) GND VO2+ ( 5 V) VO1+ ( 12 V) MB3778 ■ HOW TO SET THE OUTPUT VOLTAGE The output voltage is set using the connections shown in “Connection of error Amp. Output Voltage V0 ≥ 0” and “Connection of Error Amp. Output Voltage V0 < 0”. The error amplifier power is supplied by the reference voltage circuit as is that of the other internal circuits. The common mode input voltage range is from 1.05 V to 1.45 V. Set 1.23 V (VREF/2) as the reference input voltage that is connected to either inverting or non-inverting input terminals. • Connection of Error Amp. Output Voltage V0 ≥ 0 VREF R VO + VO + = R1 VREF 2 × R2 (R1 + R2) + PIN 5 or PIN 12 − R R2 RNF • Connection of Error Amp. Output Voltage V0 < 0 VREF R VO− = − VREF 2 × R1 (R1 + R2) + VREF R1 + PIN 5 − R R2 RNF VO− 13 MB3778 ■ HOW TO SET TIME CONSTANT FOR TIMER LATCH SHORT-CIRCUIT PROTECTION CIRCUIT Below Figure shows the configuration of the protection latch circuit. Each error amplifier output is connected to the inverting inputs of the short-circuit protection comparator and is always compared with the reference voltage (2.1 V) connected to the non-inverting input. When the load condition of the switching regulator is stable, the error amplifier has no output fluctuation. Thus, short-circuit protection control is also kept in balance, and the SCP terminal (pin 15) voltage is held at about 50 mV. If the load changes drastically due to a load short-circuit and if the inverting inputs of the short-circuit protection comparator go above 2.1 V, the short-circuit protection comparator output goes “Low” to turn off transistor Q1. The SCP terminal voltage is discharged, and then the short-circuit protection comparator charges the protection enable capacitor CPE according to the following formula : VPE = 50 mV + tPE × 10 − 6 / CPE 0.65 = 50 mV + tPE × 10 − 6 / CPE CPE = tPE / 0.6 (µF) When the protection enable capacitor is charged to about 0.65 V, the protection latch is set to enable the under voltage lockout circuit and the output drive transistor is turned off. The idle period is also set to 100% at the same time. Once the under voltage lockout circuit is enabled, the protection enable is released; however, the protection latch is not reset if the power is not turned off. The inverting inputs (pin 6 or 11) of the D.T.C. comparator are compared to the reference voltage (about 1.1 V) connected to the non-inverting input. To prevent malfunction of the short-circuit protection-circuit when the soft-start operation is done by using the DTC terminal, the D.T.C. comparator outputs a “High” level while the DTC terminal goes up to about 1.1 V, and then closes the SCP terminal by turning transistor Q2 on. • Protection Latch Circuit 2.46 V 1 µA S.C.P. Comp. 15 R1 Error Amp. 1 Error Amp. 2 2.1 V − − + CPE Q1 Q2 Q3 S R Latch − − + D.T.C. Comp. 14 1.1 V U.V.L.O. 6 DTC1 11 DTC2 MB3778 ■ SETTING THE IDLE PERIOD When voltage step-up, fly-back step-up or inverted output are set, the voltage at the FB terminal may go higher than the triangular wave voltage due to load fluctuation, etc. In this case the output transistor will be in full-on state(ON duty 100%). This can be prevented by setting the maximum duty for the output transistor. This is done by setting the DTC1 terminal (pin 6) voltage using resistance division of the VREF voltage as illustrated below. When the DTC1 terminal voltage is higher than the triangular waveform voltage, the output transistor is turned on. If the triangular waveform amplitude specified by the maximum duty calculation formula is 0.6 V, and the lower voltage limit of the triangular waveform is 1.3 V, the formula would be as follows (other channels are similar) : Duty (ON) max (%) =: (Vdt − 1.3 V) / 0.6 V × 100, Vdt (V) = Rb / (Ra + Rb) × VREF Also, if no output duty setting is required, the voltage should be set greater than the upper limit voltage of the triangular waveform, which is 1.9 V. • Setting the idle time at DTC1 (DTC2 is similar) VREF 16 Ra DTC1 6 Rb Vdt 15 MB3778 ■ SETTING THE SOFT START TIME When power is switched on, the current begins charging the capacitor (CDTC1) connected the DTC1 terminal (pin 6). The soft start process operates by comparing the soft start setting voltage, which is proportional to the DTC1 terminal voltage, with the triangular waveform, and varying the ON-duty of the OUT terminal (pin 7). The soft start time until the ON duty reaches 50% is determined by the following equation: Soft start time (time until output ON duty = 50%) . ts (s) =: − CDTC1 × Ra × Rb / (Ra + Rb) × ln (1 − 1.6 (Ra + Rb) / (2.46 Rb) ) For example, if Ra = 4.7 kΩ and Rb = 10 kΩ, the result is: ts (s) =: 0.1 × CDTC1 (µF) • Soft Start on DCT1 terminal (DTC2 is similar) VREF 16 Ra DTC1 6 Rb 16 CDTC1 MB3778 ■ USING THE RT TERMINAL The triangular waves, as shown in Figure “No VREF/2 connection to external circuits from RT terminal”, act to set the oscillator frequency by charging and discharging the capacitor connected to the CT terminal using the current value of the resistor connected to the RT terminal. In addition, when voltage level VREF/2 is output to external circuits from the RT terminal, care must be taken in making the external circuit connections to adjust for the fact that I1 is increased by the value of the current I2 to the external circuits in determining the oscillator frequency (see Figure “VREF/2 connection to external circuits from RT terminal”). • No VREF/2 connection to external circuits from RT terminal Triangular wave oscillator ICT = IRT = VREF 2RT ( V2 ) REF 2 1 IRT ICT RT CT • VREF/2 connection to external circuits from RT terminal Triangular wave oscillator ICT = IRT = I1 + I2 VREF = + I2 2RT ( V2 ) REF 2 1 IRT ICT To external circuits I2 I1 RT CT 17 MB3778 ■ SYNCHRONIZATION OF ICs A fixed condenser and resistor are inserted in the CT and RT terminals of IC which becomes a master when synchronizing by using plurality of MB3778. As a result, the slave ICs oscillate automatically. The RT terminals (pin 2) of the slave ICs are connected to the VREF terminal (pin 16) to disable the charge/discharge circuit for triangular wave oscillation. The CT terminals of the master and slave ICs are connected together. • Connection of Master, Slave MB3778 (MASTER) CT RT MB3778 (SLAVE) MB3778 (SLAVE) 18 VCC MB3778 ■ TYPICAL CHARACTERISTICS Power supply voltage vs. Reference voltage 2.5 0 0 4 8 12 16 1.0 0 0 20 Power supply voltage VCC (V) VCC = VCTL = 6 V IOR = −1 mA Reference voltage VREF (V) 2.45 2.44 2.43 2.42 2.41 −20 0 20 40 60 80 100 Triangular waveform Upper / Lower Limit voltage (V) Reference voltage vs. Temperature 2.40 −40 4 8 12 16 20 Power supply voltage VCC (V) 2.47 2.46 Ta = +25 °C 2.0 Average supply current ICCa (mA) Ta = +25 °C 5.0 Reference voltage VREF (V) Power supply voltage vs. Average supply current Timing capacitor vs. Triangular waveform Upper/Lower Limit voltage 2.2 2.0 Upper limit 1.8 1.6 1.4 1.2 Lower limit 1.0 VCC = 6 V RT = 15 kΩ Ta = +25 °C 0.8 102 103 Timing capacitor CT (pF) 104 Temperature Ta (°C) Error Amp. Max. output voltage vs. Frequency Collector saturation voltage (V) 5.0 VCC = 6 V Ta = +25 °C 4.0 3.0 2.0 1.0 Error Amp. Max. output voltage (V) Collector saturation voltage vs. Sink Current 3.0 VCC = 6 V Ta = +25 °C 2.0 1.0 0 100 500 1 k 5 k 10 k 50 k 100 k 500 k Frequency (Hz) 0 0 100 200 300 400 Sink current (mA) 500 19 MB3778 (Continued) Timing resistor vs. Oscillation frequency Triangular waveform cycle vs. Timing capacitor 100 Triangular waveform cycle (µs) Oscillation frequency fOSC (Hz) VCC = 6 V Ta = +25 °C 1M 100 k CT = 150 pF 10 1 CT = 1500 pF 10 k VCC = 6 V RT = 15 kΩ Ta = +25 °C 102 103 104 Timing capacitor CT (pF) 105 CT = 15000 pF 1k 1k 5 k 10 k 50 k100 k Timing resistor RT (Ω) 500 k Temperature vs. Frequency stability 100 VCC = 6 V CT = 330 pF RT = 15 kΩ 0 VCC = 6 V CT = 330 pF RT = 15 kΩ Ta = +25 °C 80 Duty Dtr (%) Frequency stability fdT (%) 10 Oscillation frequency vs. Duty 60 40 20 −10 −40 −20 0 20 40 60 80 100 0 120 5k 10 k Temperature Ta (°C) VCC = 6 V Ta = +25 °C 0 1 2 3 Control voltage VCTL (V) 20 4 VCC = 6 V Ta = +25 °C 500 2.5 0 500 k 1 M Control input current Control current ICTL (µA) Reference voltage VREF (V) Control voltage vs. Reference voltage 5.0 50 k 100 k Oscillation frequency (Hz) 5 250 0 0 4 8 12 16 Control voltage ICTL (V) 20 MB3778 (Continued) Frequency vs. Gain/Phase Frequency vs. Gain/Phase (Actual Data) CNF = OPEN AV 40 CNF = 0.047 µF 180 40 90 20 90 0 0 180 −20 −90 −20 −40 −180 −40 100 1k 10 k 100 k 1M −180 10 100 Frequency f (Hz) Frequency vs. Gain/Phase (Actual Data) AV 0 180 40 90 20 0 −20 φ −40 10 100 1k 10 k Frequency f (Hz) 100 k Gain AV (dB) Gain AV (dB) 20 1k 10 k Frequency f (Hz) 100 k 1M Frequency vs. Gain/Phase (Actual Data) Phase φ (deg) CNF = 470 pF 40 −90 −20 −180 −40 10 180 AV 90 0 −90 1M CNF = 4700 pF 0 φ Phase φ (deg) 10 φ Phase φ (deg) 0 φ Gain AV (dB) 0 Phase φ (deg) Gain AV (dB) AV 20 −90 −180 100 1k 10 k Frequency f (Hz) 100 k 1M Actual Circuit VREF VREF CNF 4.7 kΩ 240 kΩ 4.7 kΩ − IN OUT 10 µF − + + Error Amp. 4.7 kΩ 4.7 kΩ 21 MB3778 (Continued) Power Dissipation vs. Ambient Temperature (SSOP) 700 500 620 600 444 400 Power dissipation PD (mW) Power dissipation PD (mW) Power Dissipation vs. Ambient Temperature (SOP) 500 400 300 200 100 0 −40 −20 0 20 40 60 80 100 Ambient temperature Ta (°C) 1100 Power dissipation PD (mW) 1000 900 800 700 600 500 400 300 200 100 22 −20 0 20 40 60 Ambient temperature Ta (°C) 200 100 0 −40 −20 0 20 40 60 Ambient temperature Ta (°C) Power Dissipation vs. Ambient Temperature (DIP) 0 −40 300 80 100 80 100 MB3778 ■ APPLICATION 1. Equivalent series resistor and stability of smoothing capacitor The equivalent series resistor (ESR) of the smoothing capacitor in the DC/DC converter greatly affects the loop phase characteristic. The stability of the system is improved so that the phase characteristic may advance the phase to the ideal capacitor by ESR in the high frequency region (see “Gain vs. Frequency” and “Phase vs. Frequency”). A smoothing capacitor with a low ESR reduces system stability. Use care when using low ESR electrolytic capacitors (OS CONTM) and tantalum capacitors. Note: OS CON is the trademark of Sanyo Electnic Co., Ltd. DC/DC Converter Basic Circuit L Tr RC VIN D RL C Gain vs. Frequency Phase vs. Frequency 0 0 −20 −40 −60 10 (2) (1) : RC = 0 Ω (2) : RC = 31 mΩ 100 (2) −90 −180 (1) 1k 10 k Frequency f (Hz) Phase φ (deg) Gain AV (dB) 20 100 k 10 (1) : RC = 0 Ω (2) : RC = 31 mΩ 100 1k 10 k Frequency f (Hz) (1) 100 k 23 MB3778 Reference data If an aluminum electrolytic smoothing capacitor (RC ≅ 1.0 Ω) is replaced with a low ESR electrolytic capacitor(OS CONTM : RC ≅ 0.2 Ω), the phase margin is reduced by half(see Fig. 37 and 38). DC/DC Converter AV vs. φ characteristic Test Circuit VOUT VO+ CNF AV vs. φ characteristic Between these points − FB + −IN VIN +IN R2 R1 VREF/2 Error Amp. DC/DC Converter +5 V output Gain vs. Phase VCC = 10 V RL = 25 Ω CP = 0.1 µF 40 180 φ 20 90 62 ° 0 0 −20 −40 10 100 1k Figure 38 VCC = 10 V RL = 25 Ω CP = 0.1 µF Gain AV (dB) 40 20 GND 180 90 φ 0 27 ° −20 0 −90 100 AI Capacitor 220 µF (16 V) RC ≅ 1.0 Ω : fOSC = 1 kHz DC/DC Converter +5 V output Gain vs. Phase AV 24 + − −180 100 k 10 k 60 −40 10 VO+ −90 Phase φ (deg) Gain AV (dB) AV Phase φ (deg) 60 1k Frequency f (Hz) 10 k −180 100 k VO+ + − OS CONTM 22 µF (16 V) RC ≅ 0.2 Ω : fOSC = 1 kHz GND MB3778 ■ ORDERING INFORMATION Part number MB3778P MB3778PFV MB3778PF Package Remarks 16-pin Plastic DIP (DIP-16P-M04) 16-pin Plastic SSOP (FPT-16P-M05) 16-pin Plastic SOP (FPT-16P-M06) 25 MB3778 ■ PACKAGES DIMENSION 16-pin, Plastic DIP (DIP-16P-M04) +0.20 19.55 –0.30 .770 +.008 –.012 INDEX-1 6.20±0.25 (.244±.010) INDEX-2 0.51(.020)MIN 4.36(.172)MAX 0.25±0.05 (.010±.002) 3.00(.118)MIN 0.46±0.08 (.018±.003) +0.30 0.99 –0 .039 +.012 –0 1.27(.050) MAX C +0.30 1.52 –0 +.012 –0 .060 2.54(.100) TYP 7.62(.300) TYP 15°MAX 1994 FUJITSU LIMITED D16033S-2C-3 Dimensions in mm (inches) . (Continued) 26 MB3778 (Continued) 16-pin, Plastic SSOP (FPT-16P-M05) * 5.00±0.10(.197±.004) 0.17±0.03 (.007±.001) 9 16 * 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 8 0.65(.026) 0.10(.004) C (Mounting height) "A" 0.24±0.08 (.009±.003) 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 F16013S-3C-5 Dimensions in mm (inches) . (Continued) 27 MB3778 (Continued) 16-pin, Plastic SOP (FPT-16P-M06) 2.25(.089)MAX 10.15 +0.25 –0.20 .400 +.010 –.008 0.05(.002)MIN (STAND OFF) INDEX 5.30±0.30 (.209±.012) +0.40 6.80 –0.20 +.016 .268 –.008 7.80±0.40 (.307±.016) "B" 1.27(.050) TYP 0.45±0.10 (.018±.004) +0.05 Ø0.13(.005) 0.15 –0.02 +.002 .006 –.001 M Details of "A" part Details of "B" part 0.40(.016) 0.15(.006) 0.20(.008) "A" 0.10(.004) 8.89(.350)REF C 0.50±0.20 (.020±.008) 0.20(.008) 0.18(.007)MAX 0.18(.007)MAX 0.68(.027)MAX 0.68(.027)MAX 1994 FUJITSU LIMITED F16015S-2C-4 Dimensions in mm (inches) . 28 MB3778 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 F0012 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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