New Products MB39C313A 4 -Channel DC/DC Converter IC for Large LCD Panels MB39C313A A system power management IC capable of supplying the four types of voltages required in large LCD panels in a single chip. With built-in switching FET for large current operation, this product is suitable for applications such as large LCD TVs and monitors. Overview Sufficient protective functions Short-circuit protection, overcurrent protection, overvoltage protection, undervoltage lockout, over temperature protection Built-in soft-start circuit independent of loads (Vlogic, Vs) Frequency setting by input pin: 500kHz/750kHz Package: TSSOP-28 (with exposed PAD) Lead-free/conforms to RoHS Directive ● This product is a system power management IC with a builtin 4-channel power management control block. It consists of a 2-channel DC/DC converter with switching FET and a 2-channel charge pump type DC/DC converter. The DC/DC converter block offers excellent stability against input voltage fluctuations with the input voltage feed-forward method. The output voltage in the charge pump circuit block can be set by an external resistor using the output voltage feedback method. This product contributes to a reduction in the parts cost as a result of the built-in switching FET and phase compensator. Product Features ● ● ● ● Functions Figure 1 presents the block diagram of this product. Photo 1 External View Power supply voltage range: 8V to 14V DC/DC converter with built-in switching FET Step-down converter (Vlogic): Output 1.8V to 3.3V 1.5A (max.) Step-up converter (Vs): Output 17.7V 1.5A (max.) Charge pump with output voltage feedback method Inverting charge pump (VGL): 100mA (max.) Step-up charge pump (VGH): 100mA (max.) Excellent line regulation with feed-forward control (Vlogic, Vs) Built-in phase compensator (Vlogic) Built-in startup sequence control function ● ● ● ● ● ● ● ● ● ● 2010 No.1 FIND Vol.28 New Products MB39C313A Figure 1 MB39C313A Block Diagram A BOOT FBB Error Amp1 L priority 15 <<Vlogic (Buck)>> VB REG 4V (SWB + 4 V) 17 VINB 20 21 enb1 1.213 V RON=230 m7 at VGS=4 V PWM Comp.1 PWM Logic Control VTH 1.213 V ± 1.5% OSC_CTL fosc or fosc/2 or fosc/4 0.9V VINB SCP Comp. 18 Vlogic (3.3 V/1.5 A Max) LEVEL CONV Current Limmit 0.6V B DRV A SWB ILIM Comp.1 Saw tooth Generator COMP 2 FB 1 SS 28 Current Limmit GD C RON=10 7 at VGS=-12 V Vs (17.7 V / 1.5 A Max) LEVEL CONV SW PWM Logic Control PWM Comp.2 OS 3 18.7 V Saw tooth Generator AVIN 1.03 V <<Vs (Boost)>> VTH 1.146 V ± 0.9% 1.146 V enb2 B OVP Comp. Error Amp2 L priority 4 DRV 5 RON=110 m7 at VGS=5 V 6 ILIM Comp.2 PGND 7 27 GD Comp. <<VGL (Negative Charge Pump)>> AVIN FBN Error Amp3 13 DRN DRV 11 C VGL (-5 V / 100 mA Max) enb3 VTH 0 V ± 36 mV D Current Control Logic SUP <<VGH (Positive Charge Pump)>> L priority Error FBP 14 Amp4 DRP Current Control Logic enb4 8 DRV 10 VGH (32 V/100 mA Max) VTH 1.213 V ± 2.1% FREQ 12 OSC DLY1 L:OTP OTP DLY Comp.1 25 D L:Protection UVLO 1.213 V enb1 H:Vlogic ON enb2 H:Vs ON enb3 H:VGL ON enb4 H:VGH ON L : UVLO DLY2 26 DLY Comp.2 Vlogic ss finish 1.213 V AVIN 22 VREF Buffer BGR Power ON/OFF CTL 16 9 EN1 EN2 VIN=12 V 19 NC 24 REF 1.213 V 23 GND 2010 No.1 FIND Vol.28 New Products MB39C313A ■P ower management voltage functions Generates the voltages for the controller (Vlogic), source driver (Vs), and gate driver (VGL, VGH) required in general LCD panels. Vlogic (Vo1): Step-down converter The step-down converter uses pulse width modulation (PWM) with built-in N-channel switching FET. The input voltage feed-forward method ensures excellent line regulation. Phase compensation constant is set by a built-in compensation circuit and an external ceramic capacitor. The main switch of the converter is an N-channel FET with 3.2A peak current rating and the gate drive circuit is referenced to the SWB pin (source terminal of N-channel switching FET). An external capacitor connected between SWB pin and BOOT pin is charged to 4V by the built-in 4V regulator during the period when N-channel FET is off cycle. Since this capacitor turns ON the N-channel FET fully, it bootstraps the gate driving voltage higher than the power supply voltage along with the N-channel FET. As a consequence, the gate-source voltage reaches 4V while the N-channel FET is on. can increase the maximum output voltage. ■S tartup sequence The startup sequence can be set using EN1 and EN2. The startup sequence timing can be adjusted by the capacitors connected to DLY1 and DLY2. When EN1 is set at“H”with EN2 fixed at“H,”Vlogic starts up first and VGL starts up after delay time DLY1. Vs and VGH start up simultaneously after delay time DLY2 (Figure 2). When EN2 is set at“H”with Vlogic already operating and with EN1 at“H,”the delay time DLY2 starts from the EN2 rising edge (Figure 3). If EN2 is set to“H”before Vlogic operates, DLY2 starts after Vlogic finishes start up. ■S oft-start function Vlogic and Vs are equipped with a soft-start function to prevent inrush current at startup. The soft-start period is approximately 1ms for Vlogic (fixed) and is set by the external capacitor for Vs. ■V arious protective functions Vlogic: Step-down converter Short-circuit protection: Protective circuit active at FBB pin＜0.9V. Overcurrent protection: Protective circuit active at Vlogic output current≧3.2A. Vs: Step-up converter Overvoltage protection: Protective circuit active at Vs output≧18.7V. Overcurrent protection: Protective circuit active at SW pin current≧3.5A. VGL: Inverting charge pump: No protection circuit VGH: Step-up charge pump: No protection circuit Undervoltage lockout protection (UVLO) All channels shut down at AVIN≦6V. Over temperature protection (OTP) Switching is stopped when the junction temperature reaches 150℃ . Switching is resumed when the junction temperature drops to 135℃ . ● Vs (Vo2): Step-up converter The step-up converter containing a build-in N-channel switching FET and an external diode operates as a pulse width modulated (PWM) asynchronous DC/DC converter. It adopts the input voltage feed-forward method to ensure excellent line regulation under voltage mode. Phase compensation is set by external parts. It operates in continuous conduction mode independent of loading current due to the operation of the built-in P-channel switching FET (ON resistance 10Ω) connected between the SW pin and the OS pin along with the external flyback diode. ● ● ● ● VGL (Vo3): Inverting charge pump The inverting charge pump operates at a fixed frequency and the output voltage can be set by the divider ratio of the external resistor divider. When the charge pump driver is connected to the supply voltage (VIN), the maximum output voltage is −VIN＋ Vloss. Vloss includes voltage drops in the output diode and driver transistors. The addition of more charge pump stages can increase the maximum negative voltage value. VGH (Vo4): Step-up charge pump Like the inverting charge pump, the step-up charge pump operates at a fixed frequency and the output voltage can be set by the divider ratio of the external resistor divider. By connecting the step-up converter output (Vs) or MB39C313A input (VIN) to the charge pump input (SUP), the maximum output voltage becomes Vsup＋Vs. The addition of more charge pump stages ● ■S witching frequency Table 1 presents the switching frequency. Table 1 Switching Frequency Terminal FREQ Setting Switching frequency H 750kHz L 500kHz 2010 No.1 FIND Vol.28 New Products Application Examples Figure 4 presents application examples of this product. Evaluation Board MB39C313A Figure 2 Startup Sequence when EN2 is always set to“H” EN2 EN1 DLY2 We offer an evaluation board to aid evaluation of this product (Photo 2). Vs Vin Vin Vlogic 0V Difference from MB39C313 The charge pump current for VGL and VGH has been expanded to 100mA (max.). Fall time of each channel depends on load current and feedback resistance. VGH VGL DLY1 GD Figure 3 Startup Sequence when EN1 and EN2 are set to“H”separately Future Development FUJITSU has developed system power management ICs for LCD panels by integrating D/A converters and DC/DC converters using the core of our power management IC analog technology. In the future, we will continue to realize developments that address our customer needs in order to enable the further integration of peripheral functions as well as cost reduction. ✱ EN2 EN1 DLY2 Fall time of each channel depends on load current and feedback resistance. VGH Vs Vin Vin Vlogic 0V DLY1 VGL GD Figure 4 Application Examples DC/DC converter DDR TCON Step-down conversion DC/DC 3.3V MB39C313A Step-up conversion DC/DC 17.7V Charge pump 32V Source driver Gate driver Photo 2 Evaluation Board LCD panel Charge pump −5V VIN＝8V to 14V 2010 No.1 FIND Vol.28