NX2138

NX2138 SINGLE CHANNEL MOBILE PWM CONTROLLER PRODUCTION DATA SHEET Pb Free Product The NX2138 controller IC is a compact Buck controller n IC with 16 lead MLPQ package designed for step down n DC to DC converter in portable applications. It can be n selected to operate in synchronous mode or non-syn- n chronous mode to improve the efficiency at light n load.Constant on time control provides fast response, good line regulation and nearly constant frequency un- n der wide voltage input range. The NX2138 controller is optimized to convert single supply up to 24V bus voltage to as low as 0.75V output voltage. Over current n protection and FB UVLO followed by latch feature. Other n features includes: internal boost schottky diode, 5V gate n drive capability, power good indicator, over current pro- n tection, over voltage protection and adaptive dead band n control. n n n n DESCRIPTION FEATURES Internal boost schottky diode Ultrasonic mode operation available Bus voltage operation from 4.5V to 24V Less than 1uA shutdown current with Enable low Excellent dynamic response with constant on time control Selectable between synchronous CCM mode and diode emulation mode to improve efficiency at light load Programmable switching frequency Current limit and FB UVLO with latch off Over voltage protection with latch off Power good indicator available Pb-free and RoHS compliant APPLICATIONS Notebook PCs and Desknotes Tablet PCs/Slates On board DC to DC such as 12V to 3.3V, 2.5V or 1.8V Hand-held portable instruments TYPICAL APPLICATION PGOOD 100k 5V 10 1u 1u 9 2 PVCC HDRV 12 VCC 2.2 BST 13 1u SW 11 1.5uH Vout 1.8V/7A IRF7807 4 PGOOD TON 16 1n 2x10uF 1MEG VIN 7V~22V NX2138 2R5TPE330MC 330uF LDRV 8 AO4714 15 ENSW /MODE 2 14 NC NC AGND 6 OCSET 10 1 VOUT FB 3 PGND 7 5k 10.5k 7.5k Figure1 - Typical application of NX2138 ORDERING INFORMATION Device NX2138CMTR Rev. 1.6 12/09/09 Temperature -10o C to 100o C Package 4X4 MLPQ-16L Pb-Free Yes 1 NX2138 ABSOLUTE MAXIMUM RATINGS VCC,PVCC to GND & BST to SW voltage ............ -0.3V to 6.5V TON to GND ......................................................... -0.3V to 28V HDRV to SW Voltage .......................................... -0.3V to 6.5V SW to GND ......................................................... -2V to 30V All other pins ........................................................ VCC+0.3V Storage Temperature Range ..................................-65oC to 150oC Operating Junction Temperature Range .................-40oC to 150oC ESD Susceptibility ............................................... 2kV 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 4x4 16-LEAD PLASTIC MLPQ ENSW/MODE θ JA ≈ 46o C/W TON 16 15 VO 1 VCC 2 FB 3 14 13 12 HDRV BST 11 SW 10 OCSET 9 PVCC 8 LDRV SYM 17 PAD PGOOD 4 5 NC 6 AGND 7 PGND ELECTRICAL SPECIFICATIONS Unless otherwise specified, these specifications apply over Vcc =5V, VIN=15V and TA =25oC, unless otherwise specified. PARAMETER VIN recommended voltage range Shut down current VCC,PVCC Supply Input voltage range Operating quiescent current Shut down current Rev. 1.6 12/09/09 NC Test Condition Min 4.5 TYP MAX 24 Units V uA V mA uA ENSW=GND Vin No switching, ENSW=5V ENSW=GND 4.5 1 5.5 1.6 1 2 NX2138 PARAMETER VCC UVLO Under-voltage Lockout threshold Falling VCC threshold ON and OFF time TON operating current ON -time Minimum off time FB voltage Internal FB voltage Input bias current Line regulation OUTPUT voltage Output range VOUT shut down discharge resistance Soft start time PGOOD Power good high rising threshold PGOOD propagation delay filter Power good hysteresis Pgood output switch impedance Pgood leakage current SW zero cross comparator Offset voltage HighNSide Driver (CL=3300pF) Output Impedance , Sourcing Current Output Impedance , Sinking Current Rise Time Fall Time Deadband Time Low Side Driver (CL=3300pF) Output Impedance, Sourcing Current Output Impedance, Sinking Current Rise Time Fall Time Deadband Time Vref VCC from 4.5 to 5.5 SYM VCC _UVLO 3.9 3.7 VIN=15V, Rton=1Mohm VIN=9V,VOUT=0.75V,Rton= 1Mohm 4.1 3.9 15 312 380 0.739 -1 0.75 ENSW/MODE=GND 30 1.5 390 590 0.75 468 800 0.761 100 1 3.3 4.5 4.3 V V uA ns ns V nA % V ohm ms Test Condition Min TYP MAX Units 90 NOTE1 NOTE1 2 5 13 1 5 % Vref us % ohm uA mV R source(Hdrv) R sink (Hdrv) I=200mA I=200mA 1.5 1.5 50 50 30 ohm ohm ns ns ns THdrv(Rise) 10% to 90% THdrv(Fall) 90% to 10% Tdead(L to Ldrv going Low to Hdrv going H) High, 10% to 10% R source(Ldrv) Rsink(Ldrv) I=200mA I=200mA 1.5 0.5 50 50 10 ohm ohm ns ns ns TLdrv(Rise) 10% to 90% TLdrv(Fall) 90% to 10% Tdead(H to SW going Low to Ldrv going L) High, 10% to 10% Rev. 1.6 12/09/09 3 NX2138 PARAMETER ENSW/MODE threshold and bias current PFM/Non Synchronous Mode Ultrasonic Mode Synchronous Mode Shutdown mode Input bias current Current Limit Ocset setting current Over temperature Threshold Hysteresis Under voltage FB threshold Over voltage Over voltage tripp point Internal Schottky Diode Forward voltage drop Leave it open or use limits in spec ENSW/MODE=VCC ENSW/MODE=GND 20 SYM Test Condition Min TYP MAX Units 80% V CC 60% V CC 2 0 5 -5 24 155 15 70 125 forward current=50mA 500 VCC+0 .3V 80% VCC 60% VCC 0.8 V V V V uA uA 28 uA o o C C %Vref %Vref mV Rev. 1.6 12/09/09 4 NX2138 PIN DESCRIPTIONS PIN NUMBER PIN SYMBOL 1 VOUT PIN DESCRIPTION This pin is directly connected to the output of the switching regulator and senses the VOUT voltage. An internal MOSFET discharges the output during turn off. This pin supplies the internal 5V bias circuit. A 1uF X7R ceramic capacitor is placed as close as possible to this pin and ground pin. 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 from 0.75V to 3.3V. PGOOD indicator for switching regulator. It requires a pull up resistor to Vcc or lower voltage. When FB pin reaches 90% of the reference voltage PGOOD transitions from LO to HI state. Not used. Analog ground. Power ground. Low side gate driver output. Provide the voltage supply to the lower MOSFET drivers. Place a high frequency decoupling capacitor 1uF X5R to this pin. This pin is connected to the drain of the external low side MOSFET and is the input of over current protection(OCP) comparator. An internal current source is flown to the external resistor which sets the OCP voltage across the Rdson of the low side MOSFET. This pin is connected to source of high side FETs and provide return path for the high side driver. It is also the input of zero current sensing comparator. High side gate driver output. This pin supplies voltage to high side FET driver. A high freq 1uF X7R ceramic capacitor and 2.2ohm resistor in series are recommended to be placed as close as possible to and connected to this pin and SW pin. Not used. Switching converter enable input. Connect to VCC for PFM/Non synchronous mode, connected to an external resistor divider equals to 70%VCC for ultrasonic, connected to GND for shutdown mode, floating or connected to 2V for the synchronous mode. VIN sensing input. A resistor connects from this pin to VIN will set the frequency. A 1nF capacitor from this pin to GND is recommended to ensure the proper operation. Used as thermal pad. Connect this pad to ground plane through multiple vias. 2 3 VCC FB 4 5 6 7 8 9 10 PGOOD NC AGND PGND LDRV PVCC OCSET 11 12 13 14 15 SW HDRV BST NC ENSW/ MODE 16 TON 17 PAD Rev. 1.6 12/09/09 5 NX2138 BLOCK DIAGRAM VCC(2) Bias 4.3/4.1 Disable_B Thermal shutdown ON time pulse genearation R S Q POR BST(13) VIN start HD ODB HDRV(12) FET Driver HD_IN SW(11) 5V PVCC(9) LDRV(8) OCP_COMP Mini offtime 400ns PGND(7) 1.8V VIN TON(16) VOUT VOUT FB(3) VREF=0.75V start soft start VCC ENSW /MODE(15) 1M 1M MODE SELECTION Disable PFM_nonultrasonic Sync FB 1.25*Vref/0.7VREF OCP_COMP POR FBUVLO_latch Diode emulation HD OCSET(10) OVP AGND(6) FBUVLO_latch 0.7*Vref FB VOUT(1) VOUT start 0.9*Vref SS_finished PGOOD(4) Figure 2 - Simplified block diagram of the NX2138 Rev. 1.6 12/09/09 6 NX2138 TYPICAL APPLICATION (VIN=7V to 22V, VOUT=1.8V/7A) PGOOD R1 100k 5V R2 10 C1 1u C2 1u 4 PGOOD TON 16 C3 1n R4 1MEG VIN 7V~22V CI1 2x10uF M1 9 2 PVCC VCC HDRV 12 R8 2.2 BST 13 C4 1u SW 11 IRF7807 Lo 1.5uH Vout 1.8V/7A CO1 2R5TPE330MC 330uF AO4714 R3 2.2 C5 1.5n NX2138 M2 LDRV 8 R5 5k 15 ENSW /MODE 2 14 NC NC AGND 6 OCSET 10 1 VOUT FB 3 PGND 7 R6 10.5k R7 7.5k Figure 3 - Demo board schematic Rev. 1.6 12/09/09 7 NX2138 Bill of Materials Item 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Quantity 2 1 2 2 1 1 1 1 1 1 2 1 1 1 1 1 Reference CI1 CO1 C1,C2,C4 C3 C5 Lo M1 M2 R1 R2 R3,R8 R4 R5 R6 R7 U1 Value 10uF/X5R/25V 2R5TPE330MC 1uF 1nF 1.5nF DO5010H-152 IRF7807 AO4714 100k 10 2.2 1M 5k 10.5k 7.5k NX2138 Manufacture SANYO COILCRAFT IR IR NEXSEM INC. Rev. 1.6 12/09/09 8 NX2138 Demoboard waveforms Fig.4 Startup (CH2 1.8V OUTPUT, CH3 PGOOD) Fig.5 Turn off (CH2 1.8V OUTPUT, CH3 PGOOD) Fig.7 Output transient in PFM mode (CH1 SW, CH2 1.8V OUTPUT AC, CH4 OUTPUT CURRENT) Fig.8 Start into short (CH3 VOUT, CH4 OUTPUT CURRENT) Fig. 9 Output ripple at full load (CH1 SW, CH2 1.8V OUTPUT AC, CH4 OUTPUT CURRENT) Rev. 1.6 12/09/09 Fig. 10 Output ripple at light load in PFM mode(CH1 SW, CH2 1.8V OUTPUT AC) 9 NX2138 Demoboard waveforms(Cont') Fig. 11 Output ripple at no load in synchronous mode (CH1 SW, CH2 1.8V OUTPUT AC, CH4 OUTPUT CURRENT) Fig. 12 Dynamic response in synchronous mode (CH2 1.8V OUTPUT AC, CH4 OUTPUT CURRENT) Fig. 13 Dynamic response in synchronous mode (CH2 1.8V OUTPUT AC, CH4 OUTPUT CURRENT) Fig. 14 Dynamic response in PFM mode (CH2 1.8V OUTPUT AC, CH4 OUTPUT CURRENT) VIN=12V, VOUT=1.8V 95.00% 90.00% OUTPUT EFFICIENCY(%) 85.00% 80.00% 75.00% 70.00% 65.00% 60.00% 55.00% 50.00% 10 100 1000 10000 OUTPUT CURRENT(mA) Fig. 15 Dynamic response in PFM mode (CH2 1.8V OUTPUT AC, CH4 OUTPUT CURRENT) Rev. 1.6 12/09/09 Fig. 16 Output efficiency 10 NX2138 APPLICATION INFORMATION Symbol Used In Application Information: VIN VOUT IOUT FS - Input voltage - Output voltage - Output current - Working frequency FS is around 220kHz. Output Inductor Selection The value of inductor is decided by inductor ripple current and working frequency. Larger inductor value normally means smaller ripple current. However if the inductance is chosen too large, it brings slow response and lower efficiency. The ripple current is a design freedom which can be decided by design engineer according to various application requirements. The inductor value can be calculated by using the following equations: DVRIPPLE - Output voltage ripple DIRIPPLE - Inductor current ripple Design Example The following is typical application for NX2138, the schematic is figure 1. VIN = 7 to 22V VOUT=1.8V FS=220kHz IOUT=7A DVRIPPLE