NX2422

NX2422 TWO PHASE SYNCHRONOUS PWM CONTROLLER WITH INTEGRATED FET DRIVER, DIFFERENTIAL CURRENT SENSE & 5V BIAS REGULATOR PRELIMINARY DATA SHEET Pb Free Product 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 offers ripple cancelation for both input and output. The n Low Impedance On-board Drivers NX2422 uses differential remote sensing using either cur- n Hiccup current limit and IOUT indication rent sense resistor or inductor DCR sensing to achieve n Power Good for power sequencing accurate current matching between the two channels. n EN2_B pin allows the slave channel on and off while 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 12V BUS R10 2N3904 DESCRIPTION FEATURES APPLICATIONS TYPICAL APPLICATION C11 C10 VCCDRV 2N3904 BST1 C12 HDRV1 SW1 Q1 L1 5V R13 R14 VOUT C13 Q2 R29 C15 C14 C31 R11 C30 PVCC LDRV1 5VCC REFIN AGND CSCOMP R16 R17 C28 CS+1 R28 NX2422 CS-1 R15 C29 C17 BST2 C19 HDRV2 SW2 Q3 C18 RT IOUT/IMAX C27 R18 C26 L2 R27 C20 C21 VCOMP R19 C25 LDRV2 Q4 C22 FB R20 EN2_B CS+2 CS-2 R24 R26 VOUT PGND(PAD) INREFOUT/POK C24 Ref for external circuitry 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 24 LEAD PLASTIC MLPQ VCCDRV LDRV1 PVCC LDRV2 SW1 24 23 22 21 20 19 HDRV1 BST1 5VCC AGND EN2_B CS+1 1 2 3 4 5 6 7 CS-1 8 CS-2 9 CS+2 10 11 12 IOUT/IMAX VCOMP RT PGND(PAD) 18 17 HDRV2 BST2 SW2 θJA ≈ 30.5o C/W 16 INREFOUT/POK 15 REFIN 14 CSCOMP 13 FB 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 5VCC Supply Current (static) PVCC Supply Current (Dynamic) VBST Voltage Range VBST Supply Current ((Dynamic)) Rev.2.1 12/01/08 SYM VCC TEST CONDITION MIN 4.5 - TYP 5 6.7 4.4 MAX 5.5 UNITS V mA mA ICC (Static) REFIN=GND, EN2_B=5V REFIN=5V, EN2_B=GND, ICC Freq=200Khz per phase (Dynamic) CLOAD=2200PF VBST to VSW REFIN=5V, EN2_B=GND, VBST Freq=200Khz per phase (Dynamic) CLOAD=2200PF 4.5 5 4.5 5.5 V mA 2 NX2422 PARAMETER 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 Gain Open Loop 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 SYM TEST CONDITION MIN TYP MAX UNITS VCC_UVLO VCC_Hyst VCC Rising VEN2_B Rising 4.1 0.4 0.82 80 0.6 0.2 V V V mV V % KHz V V V % % VREF 4.5V