LX2750 SINGLE INPUT SUPPLY PWM CONTROLLER WITH LDO CONTROLLER PRODUCTION DATA SHEET Pb Free Product DESCRIPTION The LX2750 controller IC is a compact synchronous Buck controller IC with 16 lead MLPQ package designed for step-down DC to DC converter applications. Selectable feedforward voltage mode control or constant on time control provides fast dynamic response. Selectable diode emulation mode greatly improves the light load efficiency. The LX2750 controller is optimized to convert single supply 12V bus voltage to as low as 0.8V output voltage. An internal regulator converts bus voltage to 5V, which provides voltage supply to internal logic and driver circuit. The LX2750 employs programmable loss-less current limiting by sensing the Rdson of synchronous MOSFET followed by hiccup feature. Feedback under voltage also triggers hiccup. Internal UVLO keeps the controller off until the bus supply voltage exceeds 9V where internal digital soft starts get initiated to ramp up output. The LX2750 employs NMOS LDO controller. Other features include: 5V gate drive for HDRV signal, 12V gate drive for LDRV signal, programmable frequency, adaptive deadband control. FEATURES n n Single Input 12V Bus Voltage Excellent Dynamic Response with Selectable Feedforward Voltage Mode Control or Constant On Time Control Diode Emulation Mode Available Programmable Switching Frequency Up to 2MHz Internal Digital Soft Start Function Programmable Over Current Protection Triggers Hiccup NMOS LDO Controller Available FB UVLO Followed by Hiccup Feature in Both Controllers 5V High Side Driver and 12 V Low Side Driver Pb-free and RoHS Compliant n n n n n n n n APPLICATIONS n n Graphic Card on Board Converters On Board DC to DC such as 12V to 3.3V, 2.5V or 1.8V Set Top Box and LCD Display ASIC Power Supplies n n TYPICAL APPLICATION VIN1 +12V 7 VIN 10 BST 15 HDRV 14 VCC VOUT1 +1.8V@8A SW 13 PGOOD Connected to 5VREG Voltage mode Connected to GND Constant on time mode 8 MODE Connected to 5VREG synchronous mode 9 FCCM Connected to GND Diode emulation mode LX2750 12 16 RT LDRV 11 FB COMP 6 2 1 VREF_OC LDO_DRV 5 REFIN 3 VOUT2 +1.1V LDO_FB 4 GPIO 17 GND(PAD) Figure1 - Typical application of LX2750 ORDERING INFORMATION Device LX2750CLQ Temperature 0 to 70o C Package 3X3 MLPQ-16L Frequency 200kHz to 2MHz Pb-Free Yes Note: Available in Tape & Reel. Append the letters "TR" to the part number. (i.e. LX2750CLQ-TR) Rev. 1.0a 07/14/10 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 1 LX2750 ABSOLUTE MAXIMUM RATINGS 5VREG to GND & BST to SW voltage ................ -0.3V to 6V VIN, LDO_DRV to GND ...................................... -0.3V to 16V BST,HDRV to GND Voltage .............................. -0.3V to 21V SW to GND ....................................................... -2V to 16V LDRV to GND .................................................... -0.3V to VIN+0.3V All other pins ..................................................... -0.3V to VCC+0.3V Storage Temperature Range ............................... -65oC to 150oC Operating Junction Temperature Range ...............-40oC to 125oC ESD Susceptibility .............................................. 1000V CAUTION: Stresses above those listed in "ABSOLUTE MAXIMUM RATINGS", may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. PACKAGE INFORMATION 3x3 16-LEAD PLASTIC MLPQ RT BST HDRV SW θ JA ≈ 46o C/W 16 15 14 13 12 PGOOD COMP 1 FB 2 11 LDRV 17 GND 10 VCC LDO_DRV 3 9 FCCM 5 6 7 8 REFIN VREF_OC VIN MODE LDO_FB 4 ELECTRICAL SPECIFICATIONS Unless otherwise specified, these specifications apply over VIN=12V and TA = 0 to 70oC. Typical values refer to TA = 25oC. PARAMETER REFOUT_OC Voltage SYM REFOUT_OC Voltage Accuracy Supply Voltage(Vin) Vin Voltage Range VREF Input Voltage Current(Static) Input Voltage Current (Dynamic) Rev. 1.0a 07/14/10 Test Condition VIN from 10V to 16V Vin Min TYP MAX Units 2.45 -0.3 2.5 2.55 0.3 V % 16 V 10 No switching,COMP=0.8V Switching with HDRV and LDRV open,COMP=1.8V 7 9 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 mA mA 2 LX2750 PARAMET ER VIN UVL O V in-Threshold V in-Hysteresis 5V REG SYM V in_UVLO V in_Hyst 5VREG Output 5VREG Max Current Test Condition Min Vin Rising Vin Falling No switching 30 TYP MAX Units 9 8 V V 5.4 50 V mA SS Soft Start time Tss_pwm F S=350kHz,MODE=5V 5.2 mS Tss_con F S=350kHz,MODE=0V 1.3 mS Oscillator (Rt) Frequency Ramp-feedforward gain Ramp Offset FS Rt=110k,MODE=5V 245 V RAMP Max Duty Cycle Min Off Tim e F S=300kHz 300 0.1 1 359 kHz V/V V 80 560 % nS Min Controlable On Time Rt Disable threshold 200 0.3 nS V Error Amplifiers Open Loop Gain (Note1) Gain Bandwidth (Note1) Input Bias Current Max Sourcing Current FB=0.7V, comp>=3V 80 10 1 3 dB MHz nA mA FB=0.9V,com p<=0.3V FB=0.7V, source 80uA FB=0.9V, sink 40uA 0.4 4.4 0.1 mA V V -2 mV 1 ohm 0.8 ohm 6 ohm 2 ohm Ib Max Sinking Current COMP High Voltage COMP Low Voltage SW zero cross comparator Offset voltage High Side Driver N Impedance , Sourcing Output Current (Note1) Output Impedance , Sinking Current (Note1) Low Side Driver Output Impedance, Sourcing Current (Note1) Output Impedance, Sinking Current (Note1) Rsource(Hdrv) BST to SW=5V, I=200mA R sink(Hdrv) BST to SW=5V, I=200mA Rsource (Ldrv) PVCC=12V R sink (Ldrv) PVCC=12V MODE,FCCM thresho ld High T hreshold Low Threshold Internal Schottky Diode Forward voltage drop Power Good T hreshold Voltage as % of Vref Hysteresis FBUVL O Feedback UVLO threshold Rev. 1.0a 07/14/10 100 2 0.8 Forward current=20mA FB ram ping up percent of nom inal V V 450 mV 85 % 5 % 60 % Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 3 LX2750 PARAMETER LDO Controller SYM Test Condition Min Open Loop Gain(Note1) Gain Bandwidth(Note1) FB Pin- Bias Current LDO FB Voltage LDO FB UVLO 0.772 percent of nom inal High Output Voltage Low Output Voltage Max Sourcing Current Min Sinking Current VIN=12V,LDOFB=0.7V, source 1.4mA LDOFB=0.9V,sink 1.4mA LDOFB=0.7V, LDODRV>8V LDOFB=0.9V, LDODRV<1V TYP MAX Units 100 dB 2 1 MHz nA 0.8 60 100 0.828 V % 11.5 V 0.4 V 2 mA 8 mA Note1: Design Guaranteed. Note Rev. 1.0a 07/14/10 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 4 LX2750 PIN DESCRIPTIONS PIN SYMBOL PIN DESCRIPTION VCC This pin is internal 5V regulator output and supplies the internal 5V bias circuit. A high freq 1uF ceramic capacitor is recommended to connect this pin to ground. BST This pin supplies voltage to high side FET driver. A high freq minimum 0.1uF ceramic capacitor is placed as close as possible to and connected to this pin and SW pin. GND Ground pin. FB This pin is the error amplifiers inverting input. This pin is connected via resistor divider to the output of the switching regulator to set the output DC voltage. COMP This pin is the output of the error amplifier and together with FB pin is used to compensate the voltage control feedback loop. SW This pin is connected to source of high side FETs and provide return path for the high side driver. HDRV High side gate driver output. LDRV Low side gate driver output. VIN Voltage supply for the internal 5V regulator, LDO controller and low side driver. RT Oscillator's frequency can be set by using an external resistor from this pin to GND. Pulling this pin down below 0.3V shuts down both controllers. LDO_FB LDO controller feedback input. This pin is connected via resistor divider to the output of the LDO to set the output DC voltage. LDO_DRV LDO controller output. This pin is controlling the gate of an external NCH MOSFET. The maximum rating of this pin is 16V. MODE Connecting this pin to 5VREG voltage control mode will be chosen. Connecting this pin to ground, constant on time control mode will be chosen. FCCM Connecting this pin to 5VREG, synchronous mode will be chosen. Connecting this pin to ground, diode emulation mode will be chosen, LDRV will be off when inductor current becomes negative current. REFIN Reference input voltage for error amplifier. VREF_OC PGOOD Rev. 1.0a 07/14/10 2.5V external reference. OCP trigger level is set by connect resistor from this pin to ground. PGOOD indicator for switching regulator. It requires a pull up resistor to Vcc or lower voltage. When FB pin reaches 85% of the reference voltage PGOOD transitions from LO to HI state. Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 5 LX2750 BLOCK DIAGRAM VCC Bias 1.25V Generator 0.8V POR BST START 9/8 VIN PGOOD PGOOD FB LDO RT START Reset dominant Hiccup HDRV 0.3V Internal RT RT OSC SW CLK START FET Drivers IFF Digital start Up comp HDin PWM/PFM control core LDRV VIN REFIN SS_half_done FB FB POR Hiccup Dis_EA COMP 60%*Vp START 9k R Latchout logic MODE MODE SELECTION FCCM MODE SELECTION VOLTAGE MODE VREF_OC CONSTANT ON TIME SYNCHRONOUS MODE DIODE EMULATION MODE SS_done VIN UVLO LDOPOR 60%*0.8V SS_DAC LDOPOR LDO amplifier LDO_DRV LDO_FB GND Figure 2 - Simplified block diagram of the LX2750 Rev. 1.0a 07/14/10 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 6 LX2750 TP2 SD L2 BUS BUS VBUS1 short R16 1k C18 220u,16v Q1 D2 MMBT3904 C1 C4 16SEPC270 OP R32 0 R31 op 5VCC R17 1k op R18 0 0 TP1 COMP R27 0 R9 14 15 16 FB MODE FCCM 12 11 R1 100k 5VCC 10 C23 1n R19 M6 C24 C8 1200p L11 C7 C10 0 R24 M5 NTD70N03R 2R5SEPC820M L12 C27 R20 22u 2 SWVOUT op 22u R2 2.15 op GND 2 JP2 J1 jp C25 1n 2 0.1u 1 R23 8k JP1 SW VOUT op op R29 R28 LDO IN LDOIN 8 7 6 5 32.4k 32k 1 68.1k 1 R12 op jumper3/200 3 3 C22 1n BUS C29 1n R22 R10 RL-8250-4-1R0M op 0 L1 0.1u SW op R11 jumper3/200 op M2 TP4 5VCC LDRV R13 C14 SW C5 1u LX2750_MLPQ16 C21 R6 op H12 op 9 8 REF_OC 7 5 LDOFB 6 REFIN 4 VIN 5VCC LDPDrv TP3 0 PGOOD PGOOD 13 SW H D rv PGOOD LDrv 3 R21 30k BST COMP 2 0 GND 1 RT 17 C13 120p H11 0 U1 D1 op M1 NTD60N02R 5 4 3 2 R8 C26 0.1u R7 8k C12 4.7n 1 R3 95.3k R14 16k JVOUT HDRV R15 10k C11 1.8n C6 0.47u,16V 1 R5 2.6k C3 10uF,16V M4 NTD60N02R 0 4 M3 op MOD=VCC PWM MOD=GND constant on time control C28 10uF,X5R,6.3V) 0 LDOOUT 3 1 2 LDO OUT C9 5VCC R33 40.2k R30 op 4 H12 4 0 C30 0.1u M8 GPIO1 R35 20k 1 1 1 2 3 2N7002 1 2 3 SW JP4 jumper2/100 8 7 6 5 9 R36 op H11 M12 op 8 7 6 5 9 M7 op 2 2 GPIO0 JP3 op M11 op R34 20k JVOUT1 1 5 4 3 2 R26 op 8 7 6 5 9 5VCC 2X(22uF,X5R,6.3V) 8 7 6 5 9 VBUS1 M13 op L11 4 M14 op L12 4 1 2 3 1 2 3 0 Figure 3 - Demo board schematic Rev. 1.0a 07/14/10 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 7 LX2750 Bill of Materials Item 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 Rev. 1.0a 07/14/10 Quantity 1 1 1 1 1 1 2 2 1 1 1 1 4 4 1 1 2 1 1 1 1 1 1 1 2 5 1 1 1 1 1 2 1 1 1 2 1 Reference C1 C3 C5 C6 C7 C8 C9 C10,C27 C11 C12 C13 C18 C21,C24,C26,C30 C22,C23,C25,C29 C28 L1 M1,M4 M6 M8 Q1 R1 R2 R3 R5 R7,R23 R8,R18,R19,R27,R32 R11 R12 R13 R14 R15 R16,R17 R21 R22 R33 R34,R35 U1 Part 16SEPC270 10uF,16V 1u 0.47u,16V 2R5SEPC820M 1200p 22uF,X5R,6.3V 22uF,X5R,6.3V 1.8n 4.7n 120p 220u,16V 0.1u 1n 10uF,X5R,6.3V RL-8250-4-1R0M NTD60N02R NTD70N03R 2N7002 MMBT3904 100k 2.15 95.3k 2.6k 8k 0 68.1k 32.4k 1 16k 10k 1k 30k 32k 40.2k 20k LX2750_MLPQ16 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 8 LX2750 Demoboard waveforms Fig.4 Startup when MODE=5V (CH1 SW 5V/DIV, CH2 SW VOUT 1V/DIV) Fig.5 Use RT pin to turn on and off (CH1 LDO VOUT 1V/DIV, CH2 SW VOUT 1V/DIV, CH3 SIGNAL on TP2 5V/DIV) Fig.6 SW VOUT ripple when MODE=5V (CH1 SW VOUT RIPPLE 50mV/DIV, CH3 SW 10V/DIV, CH4 INDUCTOR CURRENT 5A/DIV) Fig.7 SW output short(CH1 SW 10V/DIV, CH2 SW VOUT 1V/DIV, CH4 INDUCTOR CURRENT 10A/ DIV) Fig. 8 SW dynamic response when MODE=5V,FCCM=5V(CH1 SW VOUT AC 50mV/ DIV, CH4 INDUCTOR CURRENT 5A/DIV) Fig. 9 SW dynamic response when MODE=0V,FCCM=5V(CH1 SW VOUT AC 50mV/ DIV, CH4 INDUCTOR CURRENT 5A/DIV) Rev. 1.0a 07/14/10 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 9 LX2750 Demoboard waveforms(Cont') Fig. 12 LDO dynamic response when LDO load from 0.1A to 1A (CH1 LDODRV 1V/DIV, CH2 LDO VOUT AC 100mV/DIV, CH4 OUTPUT CURRENT 1A/DIV) Fig. 13 Line transient when MODE=5V(CH1 VIN 5V/DIV, CH4 SW VOUT AC 50mV/DIV) 90% 90% 80% 80% 70% 70% EFFICIENCY(%) Fig. 11 SW dynamic response when MODE=5V,FCCM=0V, load from 8mA to 10A(CH1 SW VOUT AC 50mV/DIV, CH4 INDUCTOR CURRENT 5A/DIV) EFFICIENCY(%) Fig. 10 SW dynamic response when MODE=0V,FCCM=0V, load from 3mA to 10A(CH1 SW VOUT AC 20mV/DIV, CH4 INDUCTOR CURRENT 5A/DIV) 60% 50% 40% FCCM=HIGH 30% FCCM=LOW 60% 50% 40% 30% 20% 20% 10% 10% 0% 10 100 1000 10000 0% 100 Rev. 1.0a 07/14/10 FCCM=LOW 1000 10000 OUTPUTCURRENT(mA) OUTPUTCURRENT(mA) Fig. 14 Efficiency when MODE=5V FCCM=HIGH Fig. 15 Efficiency when MODE=0V Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 10 LX2750 MLPQ 16 PIN 3 x 3 PACKAGE OUTLINE DIMENSIONS SYMBOL NAME A A1 A3 B D D2 E E2 e L M Rev. 1.0a 07/14/10 Dimensions In Millimeters MIN 0.700 0.000 MAX 0.800 0.050 Dimensions In Inches MIN 0.028 0.000 0.203REF 0.180 2.950 1.600 2.950 1.600 0.008REF 0.300 3.050 1.750 3.050 1.750 0.007 0.116 0.063 0.116 0.063 0.50BSC 0.325 MAX 0.031 0.002 0.012 0.120 0.069 0.120 0.069 0.50BSC 0.450 1.5REF 0.013 0.018 0.059REF Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 11