NX2422CMTR

NX2422 TWO PHASE SYNCHRONOUS PWM CONTROLLER WITH INTEGRATED FET DRIVER, DIFFERENTIAL CURRENT SENSE & 5V BIAS REGULATOR PRELIMINARY DATA SHEET Pb Free Product FEATURES DESCRIPTION The NX2422 is a two-phase PWM controller with inte- n Differential inductor DCR sensing eliminates the problem with layout parasitic grated FET driver designed for low voltage high current n 5V bias regulator available application. The two phase synchronous buck converter n Low Impedance On-board Drivers offers ripple cancelation for both input and output. The n Hiccup current limit and IOUT indication NX2422 uses differential remote sensing using either curn Power Good for power sequencing rent sense resistor or inductor DCR sensing to achieve n EN2_B pin allows the slave channel on and off while accurate current matching between the two channels. the master channel is working Differential sensing eliminates the error caused by PCB n Programmable frequency board trace resistance that otherwise presents when usn Prebias start up ing a single ended voltage sensing. In addition the NX2422 offers high drive current capabil- n OVP without negative spike at output ity especially for keeping the synchronous MOSFET off n Selectable between internal and external reference during SW node transition, can provide regulated 5V to n Internal Schottky diode from PVCC to BST IC biasing and drivers via 5V bias regulator, allows the n Pb-free and RoHS compliant slave channel on and off via EN2_B pin while the main channel is working. Other features: PGOOD output, pro- n Graphic card High Current Vcore Supply grammable switching frequency and hiccup current lim- n High Current on board DC to DC converter iting circuitry. applications APPLICATIONS TYPICAL APPLICATION 12V BUS C11 R10 C10 2N3904 VCCDRV BST1 2N3904 5V C12 R13 R14 HDRV1 Q1 L1 VOUT SW1 C13 PVCC C31 LDRV1 R11 Q2 C30 C14 R29 C15 5VCC AGND C29 R15 CSCOMP C28 R16 RT R17 IOUT/IMAX R28 CS+1 NX2422 REFIN CS-1 C17 C19 HDRV2 Q3 C27 C26 R18 L2 SW2 VCOMP R19 C18 BST2 LDRV2 C25 C20 R27 Q4 C21 C22 FB R20 EN2_B VOUT R26 CS+2 CS-2 R24 PGND(PAD) Ref for external circuitry INREFOUT/POK C24 Figure1 - Typical application of NX2422 ORDERING INFORMATION Device NX2422CMTR Rev.2.1 12/01/08 Temperature 0 to 70oC Package MLPQ 4x4 - 24L Frequency 50kHz to 1MHz Pb-Free Yes 1 NX2422 ABSOLUTE MAXIMUM RATINGS Vcc to PGND & BST to SW voltage .................... -0.3V to 6.5V BST to PGND Voltage ...................................... -0.3V to 35V SW to PGND .................................................... -2V to 35V All other pins .................................................... -0.3V to 6.5V Storage Temperature Range ............................... -65oC To 150oC Operating Junction Temperature Range ............... -40oC To 125oC Lead temperature(Soldering 5s) ........................... 260oC 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 LDRV2 θJA ≈ 30.5o C/W SW2 VCCDRV PVCC LDRV1 SW1 24 LEAD PLASTIC MLPQ 24 23 22 21 20 19 1 18 HDRV2 BST1 2 17 BST2 5VCC 3 16 INREFOUT/POK AGND 4 15 EN2_B 5 14 CSCOMP CS+1 6 13 FB 9 10 11 12 CS-2 IOUT/IMAX REFIN VCOMP 8 RT 7 CS+2 PGND(PAD) CS-1 HDRV1 ELECTRICAL SPECIFICATIONS Unless otherwise specified, these specifications apply over 5Vcc = 5V, PVcc= 5V, VBST-VSW =5V, EN2_B=GND, 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 Supply Voltage(Vcc) 5VCC ,PVCC Voltage Range SYM TEST CONDITION VCC 5VCC Supply Current (static) ICC (Static) REFIN=GND, EN2_B=5V PVCC Supply Current (Dynamic) REFIN=5V, EN2_B=GND, ICC Freq=200Khz per phase (Dynamic) CLOAD=2200PF VBST Voltage Range VBST to VSW VBST Supply Current ((Dynamic)) REFIN=5V, EN2_B=GND, VBST Freq=200Khz per phase (Dynamic) CLOAD=2200PF Rev.2.1 12/01/08 MIN TYP MAX UNITS 4.5 5 5.5 V - 6.7 mA 4.4 mA 4.5 5 4.5 5.5 V mA 2 NX2422 PARAMETER SYM TEST CONDITION MIN TYP MAX UNITS Under Voltage, Vcc & EN2_B VCC-Threshold VCC-Hysteresis EN2_B Threshold EN2_B Hysteresis Reference Voltage Ref Voltage Ref Voltage line regulation Oscillator (Rt) Frequency for each phase Ramp-Amplitude Voltage Ramp Peak Ramp Valley Max Duty Cycle Min Duty Cycle Transconductance Amplifiers(CSCOMP) Open Loop Gain Transconductance Voltage Mode Error Amplifier Open Loop Gain Input Offset Voltage Output Current Source Output Current Sink Output HI Voltage Output LOW Voltage SS (Internal ) Soft Start time POK/INFEROUT Threshold Hysteresis POK Voltage High Side Driver (CL=4700pF) Output Impedance , Sourcing Current Output Impedance , Sinking Current Rise Time Fall Time Deadband Time Low Side Driver (CL=10000pF) Output Impedance, Sourcing Current Output Impedance, Sinking Current Rev.2.1 12/01/08 VCC_UVLO VCC_Hyst VCC Rising VEN2_B Rising VREF Fs VRAMP 4.5V