NX2117

NX2116/2116A/2116B/2117/2117A SYNCHRONOUS PWM CONTROLLER WITH CURRENT LIMIT, POWER GOOD & OVER VOLTAGE PRELIMINARY DATA SHEET Pb Free Product The NX2116/2117 family of products are synchronous n Bus voltage operation from 2V to 25V Buck controller IC designed for step down DC to DC n Power Good indicator available in NX2116 converter applications. They are optimized to convert n Fixed 300kHz, 600kHz and 1MHz for NX2116 and 300kHz, 600kHz for NX2117 family. bus voltages from 2V to 25V to as low as 0.8V output n Internal Digital Soft Start Function voltage. The NX2116 and 2117 offer an Enable pin that can be used to program the converter's start up voltage n Less than 50 nS adaptive deadband using an external divider from bus voltage. These prod- n Enable pin to program BUS UVLO for NX2116/2117 ucts operate at fixed internal frequency of 300kHz, ex- n Programmable current limit triggers latch out by sensing Rdson of cept that NX2116A operates at 600kHz and 2116B at Synchronous MOSFET 1MHz frequency. These products employ loss-less curn No negative spike at Vout during startup and rent limiting protection by sensing the Rdson of synshutdown chronous MOSFET followed by latch out feature. Feedback under voltage triggers Hiccup. Other features are; 5V gate drive, Power good indica- n tor, Adaptive deadband control, Internal digital soft start; n Vcc undervoltage lock out and shutdown capability via n the enable pin or comp pin. n Vin1 +12V Vin2 +5V R5 68k C3 39uF R3 10 C4 1uF 6 4 1 DESCRIPTION FEATURES Graphic Card on board converters Memory Vddq Supply On board DC to DC such as 2V to 3.3V, 2.5V or 1.8V ADSL Modem APPLICATIONS L2 1uH TYPICAL APPLICATION C5 1uF Cin 270uF,18mohm D1 MBR0530T1 Vcc BST C7 0.1uF 2 OFF ON R8 10k 2N3904 R7 10k R6 12.4k C1 33pF C2 1.5nF R4 17.4k NX2116A EN Comp Fb Gnd Hdrv SW OCP Ldrv Pgood M1 L1 1uH 8 10 9 3 5 7 11 R11 3.7k M2 Co 2x (220uF,12mohm) Vout +1.8V,9A +5V R10 1k R2 16k R1 20k R9 2.61k C8 1nF Figure 1 - Typical application of 2116 Device NX2116CMTR NX2116ACMTR NX2116BCMTR NX2117CUTR NX2117ACUTR Rev. 3.0 03/14/06 ORDERING INFORMATION Frequency 300kHz 600kHz 1MHz 300kHz 600kHz Pb-Free Yes Yes Yes Yes Yes 1 Temperature 0 to 70oC 0 to 70o C 0 to 70o C 0 to 70o C 0 to 70o C Package MLPD-10L MLPD-10L MLPD-10L MSOP-10L MSOP-10L NX2116/2116A/2116B/2117/2117A ABSOLUTE MAXIMUM RATINGS VCC to GND & BST to SW voltage .................... -0.3V to 6.5V BST to GND Voltage ........................................ -0.3V to 35V SW to GND ...................................................... -2V to 35V All other pins .................................................... -0.3V to VCC+0.3V or 6.5V Storage Temperature Range ............................... -65oC to 150oC Operating Junction Temperature Range ............... -40oC to 125oC 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 NX2116/2116A/2116B 10-LEAD PLASTIC MLPD θ JA ≈ 52o C /W BST 1 HDrv 2 LDrv 3 VCC 4 PGOOD 5 Gnd (PAD) 10 SW 9 OCP 8 COMP 7 FB 6 EN BST 1 HDrv 2 GND 3 LDrv 4 VCC 5 NX2117/2117A 10-LEAD PLASTIC MSOP θJA ≈ 200o C/W 10 SW 9 OCP 8 COMP 7 FB 6 EN ELECTRICAL SPECIFICATIONS Unless otherwise specified, these specifications apply over Vcc = 5V, and TA= 0 to 70oC. Typical values refer to TA = 25oC. Low duty cycle pulse testing is used which keeps junction and case temperatures equal to the ambient temperature. PARAMETER Reference Voltage Ref Voltage Ref Voltage line regulation Supply Voltage(Vcc) VCC Voltage Range VCC Supply Current (Static) VCC Supply Current (Dynamic) Supply Voltage(VBST) VBST Supply Current (Static) VBST Supply Current (Dynamic) Rev. 3.0 03/14/06 SYM VREF Test Condition Min TYP 0.8 0.2 MAX Units V % VCC ICC (Static) Outputs not switching CLOAD=3300pF ICC (Dynamic) FS=300kHz IBST (Static) Outputs not switching IBST CLOAD=3300pF (Dynamic) FS=300kHz 4.5 5 3 TBD 5.5 V mA mA TBD TBD mA mA 2 NX2116/2116A/2116B/2117/2117A PARAMETER Under Voltage Lockout VCC-Threshold VCC-Hysteresis Oscillator Frequency SYM Test Condition Min 3.8 TYP 4 0.2 300 600 1000 1.5 95 0 2000 10 NX2116,NX2117 NX2116A, NX2117A NX2116B 6.8 MAX 4.2 Units V V kHz kHz kHz V % % umho nA mS VCC_UVLO VCC Rising VCC_Hyst VCC Falling FS 2116, 2117 2116A,2117A 2116B Ramp-Amplitude Voltage Max Duty Cycle Min Duty Cycle Error Amplifiers Transconductance Input Bias Current EN & SS Soft Start time VRAMP Ib Tss Enable HI Threshold Enable Hysterises High Side 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 OCP Adjust OCP current Power Good(Pgood) Threshold Voltage as % of Vref Hysteresis Rev. 3.0 03/14/06 1.25 150 V mV Rsource(Hdrv) Rsink(Hdrv) I=200mA I=200mA 0.9 0.65 50 50 30 ohm ohm ns ns ns THdrv(Rise) VBST-VSW=4.5V THdrv(Fall) VBST-VSW=4.5V Tdead(L to Ldrv going Low to Hdrv going High, 10%-10% H) Rsource(Ldrv) Rsink(Ldrv) I=200mA I=200mA 0.9 0.5 50 50 30 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% 40 FB ramping up 90 5 uA % % 3 NX2116/2116A/2116B/2117/2117A PIN DESCRIPTIONS PIN SYMBOL VCC PIN DESCRIPTION Power supply voltage. A high freq 1uF ceramic capacitor is placed as close as possible to and connected to this pin and ground pin. The maximum rating of this pin is 5V. This pin supplies voltage to high side FET driver. A high freq 0.1uF ceramic capacitor is placed as close as possible to and connected to these pins and respected SW pins. Ground pin. This pin is the error amplifier inverting input. It is connected via resistor divider to the output of the switching regulator to set the output DC voltage. When FB pin voltage is lower than 0.6V, hiccup circuit starts to recycle the soft start circuit after 2048 switching cycles. This pin is connected to the drain of the external low side MOSFET via resistor and is the input of the over current protection(OCP) comparator. An internal current source 40uA is flown to the external resistor which sets the OCP voltage across the Rdson of the low side MOSFET. Current limit point is this voltage divided by the Rds-on. Once this threshold is reached the Hdrv and Ldrv pins are latched out. This pin is connected to source of high side FET and provides return path for the high side driver. It is also used to hold the low side driver low until this pin is brought low by the action of high side turning off. LDRV can only go high if SW is below 1V threshold . High side gate driver output. Low side gate driver output. An open drain output that requires a pull up resistor to Vcc or a voltage lower than Vcc. When FB pin reaches 90% of the reference voltage PGOOD transitions from LO to HI state. A resistor divider is connected from the respective switcher BUS voltages to these pins that holds off the controller's soft start until this threshold is reached. An external low cost Transistor can be connected to this pin for external enable control. This pin is the output of error amplifier and is used to compensate the voltage control feedback loop. This pin can also be used to perform a shutdown if pulled lower than 0.3V. BST GND FB OCP SW HDRV LDRV PGOOD EN COMP Rev. 3.0 03/14/06 4 NX2116/2116A/2116B/2117/2117A BLOCK DIAGRAM VCC FB 0.6V Bias Generator 1.25V 0.8V UVLO POR START Hiccup Logic OC BST EN 1.25/1.15 HDRV SW OC START 0.8V OSC Digital start Up ramp S R FB 0.6V CLAMP START GND Q OC LDRV PWM Control Logic VCC COMP 1.3V CLAMP Latch Out OCP comparator FB 0.9Vref /0.85Vref 40uA OCP PGOOD Figure 2 - Simplified block diagram of the NX2116 Rev. 3.0 03/14/06 5 NX2116/2116A/2116B/2117/2117A APPLICATION INFORMATION Symbol Used In Application Information: VIN VOUT IOUT FS - Input voltage - Output voltage - Output current ∆IRIPPLE = = VIN -VOUT VOUT 1 × × LOUT VIN FS ...(2) 12V-1.8V 1.8v 1 × × = 2.55A 1uH 12V 600kHz DVRIPPLE - Output voltage ripple - Working frequency DIRIPPLE - Inductor current ripple Output Capacitor Selection Output capacitor is basically decided by the amount of the output voltage ripple allowed during steady state(DC) load condition as well as specification for the load transient. The optimum design may require a couple of iterations to satisfy both condition. Based on DC Load Condition The amount of voltage ripple during the DC load condition is determined by equation(3). Design Example The following is typical application for NX2116A, the schematic is figure 1. VIN = 12V VOUT=1.8V FS=600kHz IOUT=9A DVRIPPLE