New products MB39A103 4-Channel DC/DC Converter IC with Support for Low Voltage MB39A103 A 4-channel DC/DC converter IC with pulse width modulation type (PWM method) while achieving support for low voltage startup (1.7V∼). Four built-in channels in a TSSOP-30P/BCC-32P package enable control and soft-startup on each channel. Product Description Product Features FUJITSU has emphasized the development of power supply ICs for high-performance portable devices such as digital still cameras, and have developed products MB3785A/MB3825A/MB3827/MB3881/MB3883/MB39A 102. And now it has developed a 4-channel DC/DC converter IC, MB39A103, which is optimal for use in built-in multipurpose power supply systems used in high-performance portable devices. The digital still camera market is expected with production of approximately 29.4 million devices for 2004 in worldwide. Higher performances are being achieved rapidly in such portable devices, there will be a strong demand for further downsized power supply components. This product is a pulse width modulation type (PWM method) 4-channel DC/DC converter IC which is suitable for up conversion, down conversion and up / down conversion. Achievement of low voltage startup (1.7V ∼ ) enables operation from a low voltage. With 4 built-in channels in TSSOP-30P/BCC-32P package, control and soft-start on each channel is possible. Furthermore, a soft-start circuit and a timer latch type short-circuit detection circuit are built in to prevent inrush current when power is turned on and overcurrent at output short-circuit. This product is an optimal power supply for high function, portable devices such as digital still cameras. ■ Support for down and up / down Zeta conversion (channel 1) ■ Support for up and up / down Sepic conversion (channel 2 to channel 4) ■ Low startup voltage (channel 4): 1.7V ■ Power supply voltage range: 2.5V to 11V Photo 1 External View 2002 No.2 FIND Vol.20 91 New products MB39A103 ■ Reference voltage: 2.0V±1% DC/DC Converter Function ■ Error amplifier threshold voltage: 1.24V±1.5% Reference Voltage Block (Ref) ■ Built-in totem pole type output for MOS FET ■ Built-in load independent soft-start circuit ■ High frequency operation possible: 1MHz (Max.) ■ Short-circuit detection from external input is possible with -INS terminal The reference voltage circuit generates a temperature ― compensated reference voltage (2.0V Typ.) using the voltage supplied from power supply terminal, and it is used as the reference voltage for the IC's internal circuit. In addition, the reference voltage can be used to supply a load current of up to 1mA to an external device via the VREF terminal. Triangular Wave Oscillator Block (OSC) A triangular wave form with amplitude 0.4V to 0.9V is generated from CT terminal by connecting capacitor and resistor for timing on CT and RT terminals respectively. The triangular wave oscillation waveform is input to the PWM comparator in the IC. ■ Package: TSSOP-30P/BCC-32P Circuit Configuration Fig. 1 and 2 show the pin assignments, and Fig. 3 shows the block diagram. This product consists of function blocks described in the following section. Error Amplifier Block (Error Amp) Figure 1 Pin Assignments (TSSOP-30P) Figure 2 Pin Assignments (BCC-32P) The error amplifier is an amplifier which detects the DC/DC converter output voltage and outputs the PWM control signal. Since optional loop gain can be specified through connection of feedback resistor and capacitor to the inverted input terminal from output terminal of the error amplifier, a 26 VCCO CTL 6 25 VREF 7 RT 8 CT VCC OUT1 24 OUT2 23 OUT3 9 22 OUT4 GND 10 21 GNDO CSCP 11 20 -INS DTC3 12 19 DTC4 FB3 13 18 FB4 -INE3 14 17 -INE4 CS3 15 16 CS4 （FPT-30P-M04） 92 FIND Vol.20 No.2 2002 FB1 5 1 32 31 30 29 28 27 26 25 DTC1 2 24 VCCO CTL 3 23 OUT1 VREF 4 22 OUT2 RT 5 21 OUT3 CT 6 20 OUT4 GND 7 19 GNDO CSCP 8 18 -INS N.C 9 17 DTC4 10 11 12 13 14 15 16 FB4 VCC DTC2 -INE1 DTC1 CS1 27 CS4 4 -INE4 FB1 DTC2 CS2 28 CS3 3 -INE2 -INE1 FB2 -INE3 CS1 29 FB2 30 2 FB3 1 DTC3 CS2 -INE2 N.C ＜TOP VIEW (Transparent view from the surface)＞ （TOP VIEW） （LCC-32P-M08） New products stable phase compensation against the system is ensured. Connection of a capacitor for soft-start to CS1 terminal to CS4 terminal which are the non-inverted input terminals of the error amplifier prevents the inrush current at power MB39A103 start-up. Performing soft-start detection with error amplifier enables soft-start operation in a constant time independent of DC/DC converter output load. Figure 3 Block Diagram A CH1 ON/OFF Signal （L：ON， H：OFF） −INE1 29 Threshold Voltage Accuracy ±1.5% VREF （10μA） Error Amp1 CS1 30 PWM Comp.1 − Drive1 ＋ ＋ ＋ ＋ Pch − CTL1 L Priority FB1 DTC1 −INE2 B CH2 ON/OFF Signal （L：ON， H：OFF） Threshold Voltage Accuracy ±1.5% VREF （10μA） PWM Comp.2 − 1 Drive2 ＋ ＋ ＋ ＋ Nch − L Priority FB2 C CH3 ON/OFF Signal （L：ON， H：OFF） Transformer Threshold Voltage Accuracy ±1.5% 14 VREF （10μA） 《CH3》 L Priority Error Amp3 CS3 15 Drive3 ＋ ＋ ＋ ＋ D Nch VO3-2 5V IO＝130 mA at VCCO＝4 V Threshold Voltage Accuracy ±1.5% VREF （10μA） 《CH4》 L Priority Error Amp4 CS4 16 PWM Comp.4 − Transformer Drive4 ＋ ＋ ＋ ＋ Nch − L Priority （1.24 V） 18 DTC4 VREF −INS（100 kΩ） Short-Circuit 20 Detection Signal (L: at short-circuit) OUT4 22 GND 21 VO4-1 15 V D VO4-2 5V IO＝130 mA at VCCO＝4 V 19 Charge Current (1μA) OUT3 23 （1.24 V） 13 12 DTC3 −INE4 17 FB4 VO3-1 15 V C PWM Comp.3 − L Priority FB3 OUT2 24 IO＝130 mA at VCCO＝4 V 4 − VIN （1.7 V to 5 V） VO2 3.3 V （1.24 V） 3 CTL3 Down Conversion B 《CH2》 L Priority Error Amp2 CS2 DTC2 −INE3 OUT1 25 IO＝130 mA at VCCO＝4 V 27 2 VO1 2.5 V A （1.24 V） 28 CTL2 Down Conversion VCCO 26 《CH1》 L Priority SCP Comp. H: at SCP − SCP ＋ ErrorAmp Power Supply SCPComp. Power Supply CSCP （1 V） 11 （0.9 V） UVLO2 （0.4 V） OSC UVLO1 bias Precision ±1% ErrorAmp Power Supply （1.24 V） VREF Power VR1 ON/OFF CTL VO4-3 −7.5 V VCC 5 CTL 6 H：ON (Power ON) L：OFF (Standby Mode) VTH＝1.4 V H: UVLO Release（2.0 V） 8 RT 9 7 CT Precision ±10% Corresponds to 1MHz 10 VREF GND Note) Terminal number is for TSSOP-30P PKG. 2002 No.2 FIND Vol.20 93 New products MB39A103 PWM Comparator Block (PWM Comp.) Undervoltage Lockout Circuit Block (UVLO) This is a voltage-pulse width modulator that controls the output duty depending on input / output voltage. The output transistor is turned ON while error amplifier output voltage and DTC voltage are higher than triangular wave voltage. In the transient state at normal power start-up or during momentary drops in the power supply voltage, control IC malfunction may be induced, which can lead to system damage or deterioration. To prevent such malfunction, the undervoltage lockout circuit detects decrease in internal reference voltage level and turns OFF the output transistor to set the dead time to 100% and maintain the CSCP terminal to "L" level at the same time. If the power supply voltage exceeds the threshold voltage of the undervoltage lockout circuit, the system will restore itself. Output Block (Drive) The output circuit is constructed in totem pole style and is capable of driving external Pch MOS FET (channel 1) and Nch MOS FET (channel 2 to channel 4). Channel Control Function ON / OFF of each channel is specified by voltage specification at CTL terminal and each CS terminal. Table 1 shows the ON / OFF setting conditions. Protection Circuit Function Timer Latch Short-Circuit Protection Circuit Block (SCP, SCP Comp.) The short-circuit detection comparator detects the level of error amplifier output voltage. When the error amplifier output voltage on any channel exceeds the short-circuit detection voltage, the timer circuit operates and starts charging the capacitator CSCP externally connected to CSCP terminal. When capacitator voltage reaches approximately 0.70V, output transistor is turned OFF and the dead time is set to 100%. Furthermore, short-circuit detection from an external short-circuit detection comparator is possible using the -INS terminal. When the protection circuit operates, latch is released if power is turned ON again or if the CTL terminal is set to "L" level and the VREF terminal voltage becomes 1.3V (Min.) or less. 94 FIND Vol.20 No.2 2002 Soft-Start Function Soft-Start Circuit Block (CS) By connecting capacitors for soft-start to the CS1 terminal to CS4 terminal which are the non-inverted input terminals of the error amplifier, inrush current at power start-up can be prevented. Performing soft-start detection with the error amplifier enables soft-start operation in a constant time ✱ independent of DC/DC converter output load. Table 1 ON/OFF Setting Conditions for Each Channel CTL CS1 CS2 CS3 CS4 CH3 CH4 OFF OFF OFF OFF OFF GND GND GND GND ON OFF OFF OFF OFF H HiZ GND GND GND ON ON OFF OFF OFF H GND HiZ GND GND ON OFF ON OFF OFF H GND GND HiZ GND ON OFF OFF ON OFF H GND GND GND HiZ ON OFF OFF OFF ON ON ON ON ON ON ＊: Undefined HiZ HiZ −＊ CH2 H HiZ −＊ CH1 L H −＊ Power −＊ HiZ