Data Sheet No. PD94147 IRU3033 8-PIN PWM SWITCHER AND LINEAR CONTROLLER IC FEATURES DESCRIPTION LDO Controller allows the use of a low cost pass transistor for the I/O supply 8-Pin SOIC combines switching and linear controller Internal pre-regulator eliminates cross talk between switching and linear regulators Automatic shut down of the linear regulator when connected to the Vcc2 detect pin On-Board MOSFET Driver Fastest transient response of any controller method (0 to 100% Duty Cycle in 100ns) 1% Internal Voltage Reference Internal Under-Voltage Lockout protects MOSFET during start-up The IRU3033 IC combines a switching controller and a linear regulator controller all in a compact 8-pin surface mount package, providing a total solution for dual supply processor applications such as an Intel P55C , AMD K6 , as well as Cyrix 6X86L and the M2 processors. Typically in these applications a dual supply regulator converts 5V to 3.3V for I/O supply and a jumper programmable supply of 1.25V to 3.5V for Core supply. The linear regulator controller portion in the IRU3033 is a programmable controller allowing flexibility for the I/O regulator and has a minimum of 50mA drive current capability designed to provide ample current for an external pass transistor. The IC uses an internal regulator generated from the 12V supply to power the controller as well as the 12V supply to drive the power MOSFET, allowing a low cost N-channel MOSFET switch to be used. The IC also includes an error comparator for fast transient response, a precise voltage reference for setting the output voltage as well as a direct drive of the MOSFET for the minimum part count. APPLICATIONS Dual supply low voltage processor applications, such as: P55C , CYRIX M2 , POWER PC and AMD K6 Simple 5V to 3.3V switcher for Pentium with AGP or Pentium II applications TYPICAL APPLICATION Q1 5V R10 C1 R6 C6 R9 12V D2 C8 V12 R7 CPU Drv2 VFB2 R8 IRU3033 Drv1 I/O 5V Gnd Vcc2 Det V12(SW) VFB1 VHYST L2 C3 R3 Core C5 R4 L1 C7 Q2 C2 D1 R5 Figure 1 - Typical application of IRU3033 in a flexible mother board designed for Intel P55 , P54 , AMD K5, K6 as well as Cyrix M1 and M2 applications. Notes: P54C, P55C, Pentium II are trademarks of Intel Corp. K5 & K6 are trademarks of AMD Corp. Cyrix 6X86L, M1, M2 are trademarks of Cyrix Corp. Power PC is trademark of IBM Corp. PACKAGE ORDER INFORMATION TA (°C) 0 To 70 Rev. 1.7 07/17/02 8-PIN PLASTIC SOIC (S) IRU3033CS www.irf.com 1 IRU3033 ABSOLUTE MAXIMUM RATINGS V12,V12(SW) Supply Voltages ....................................... Fb Pin Voltages ........................................................ Storage Temperature Range ...................................... Operating Junction Temperature ................................ 20V -0.3V To 5V -65°C To 150°C 0°C To 150°C PACKAGE INFORMATION 8-PIN PLASTIC SOIC (S) TOP VIEW Drv1 1 8 V12 2 7 Drv2 VFB1 3 6 VFB2 5 Gnd V12(SW) VHYST 4 uJA =1608C/W ELECTRICAL SPECIFICATIONS Unless otherwise specified, the following specification applies over V12=V12(SW) =12V and TA=0 to 70°C. Low duty cycle pulse testing is used which keeps junction and case temperatures equal to the ambient temperature. PARAMETER Linear Controller Section Fb Voltage Initial Accuracy Fb Voltage Total Variation Fb Voltage Line Regulation Fb Input Bias Current Maximum Drive Current V12 Supply Current Switching Controller Section Fb Voltage Initial Accuracy Fb Voltage Total Variation Fb Voltage Line Regulation Fb Input Bias Current Min On Time SYM VFB2 TEST CONDITION MIN TYP MAX UNITS TJ=258C, Drv2=VFB2, CL=100mF Drv2=VFB2, CL=100mF 10<V12<14V, Drv2=VFB2, CL=100mF VFB2=1.25V VFB2=1V, VFB1=1.5V VFB2=1V, VFB1=1.5V, IDRV2=0 1.237 1.225 1.250 1.250 0.2 1.262 1.275 V V % mA mA mA VFB1 TJ=258C 1.237 1.225 IFB1 VFB1=1.25V VFB1 is sq wave with 300ns on time and 2ms off time VFB1 is sq wave with 300ns off time and 2ms on time ISOURCE=500mA, VFB1=1.5V ISINK=500mA, VFB1=1V VFB1=1V, VFB2=1.5V VFB1=1V VFB1=1.5V Load=IRL3303 IFB2 IDRV(max) I12 Min Off Time VHYST Pin Output-HI VHYST Pin Output-LO Supply Current Maximum Duty Cycle Minimum Duty Cycle Gate Drive Rise/Fall Time 2 I12(SW) DMAX DMIN VGATE www.irf.com -1 +1 50 5 1.250 1.250 0.2 800 V V % mA ns 800 ns -1 1.262 1.275 +1 11 1 10 100 0 70 V V mA % % ns Rev. 1.7 07/17/02 IRU3033 PIN DESCRIPTIONS PIN # 1 PIN SYMBOL PIN DESCRIPTION Drv1 The PWM output of the switching controller. This pin is a totem pole drive that is connected to the gate of the power MOSFET. A resistor may be placed from this pin to the gate in order to reduce switching noise. V12(SW) This pin supplies the voltage to the PWM drive and hysteresis circuitry and it is connected to the 12V supply. A 1mF, high frequency capacitor must be connected from this pin to ground to provide the peak current for charging and discharging of the MOSFET. VFB1 A resistor divider from this pin to the output of the switching regulator and ground sets the Core supply voltage. VHYST A resistor and a 10pF capacitor is connected from this pin to the V FB1 pin to set the output ripple voltage for the switching regulator. Gnd This pin is connected to the IC substrate and must be connected to the lowest potential in the system. VFB2 The feedback pin of the linear regulator. A resistor divider from this pin to the output of the linear regulator and ground sets the I/O supply voltage. Drv2 The drive pin of the linear regulator. This pin controls the base of a transistor or the gate of a MOSFET acting as the series pass element for the linear regulator. V12 This pin provides the biasing for the chip and drive for the linear regulator controller. It is connected to 12V supply. A 10V resistor in series from this pin to the 12V supply and a 1mF, high frequency capacitor connected from this pin to ground is required to filter the switching noise of the switching regulator. 2 3 4 5 6 7 8 BLOCK DIAGRAM V12(SW) VHYST VFB1 V12 2 4 3 8 Drv2 7 UVLO 5V Reg Drv 1 1 VREF PWM Control Gnd 1.25V 5 VFB2 6 Figure 2 - Simplified block diagram of the IRU3033. Rev. 1.7 07/17/02 www.irf.com 3 IRU3033 TYPICAL APPLICATION Pentium Dual Supply Application Q1 5V I/O C1 C6 R11 R10 R13 C9 R6 CPU R9 5V 12V V12 C8 Drv1 U1 R7 D2 Drv2 VFB2 R8 Gnd Vcc2 Det V12(SW) VFB1 VHYST L2 C3 R1 R3 C5 Core L1 C7 R4 Q2 C2 C4 R2 R5A R5B R5C R5D JP1 1 3 5 7 2 4 6 8 R5E D1 Figure 3 - Typical application of IRU3033 in a flexible motherboard with the 4-bit VID output voltage selection. This circuit uses a single jumper that programs the output voltage in 16 steps with 0.1V steps from 2V to 3.5V, designed for Intel P55 ,P54 , AMD K5 & K6 as well as Cyrix M1 and M2 applications. The Vcc2 Det pin automatically shuts down the I/O regulator when a single plane processor is dropped in the socket. JP1 JP1 JP1 JP1 Output 1-2 3-4 5-6 7-8 Voltage 0 0 0 0 3.5 0 0 0 1 3.4 0 0 1 0 3.3 0 0 1 1 3.2 0 1 0 0 3.1 0 1 0 1 3.0 0 1 1 0 2.9 0 1 1 1 2.8 1 0 0 0 2.7 1 0 0 1 2.6 1 0 1 0 2.5 1 0 1 1 2.4 1 1 0 0 2.3 1 1 0 1 2.2 1 1 1 0 2.1 1 1 1 1 2.0 4 www.irf.com 0 = Jumper block is installed. 1 = Jumper block is not installed. Rev. 1.7 07/17/02 IRU3033 APPLICATION PARTS LIST Pentium Dual Supply Ref Desig U1 Q1 Q2 Description LDO/Switcher IC MOSFET MOSFET Qty 1 1 1 D2 D1 Diode, GP Schottky Diode 1 1 L2 Inductor 1 L1 R1 R2 R3 R4A* R4B* R5A R5B R5C R5D R5E R6 R7 R8 R9 R10 R11 R13 C1 C2 C3 C4 C5 C6 C7 C8 C9 HS1 HS2 HS3 Inductor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Heat Sink Heat Sink Heat Sink 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 4 1 1 1 1 1 Part # IRU3033CS (8-Pin SOIC) MTP3055 (TO-220) IRL3303 (TO-220) IRL3103S (TO-263) (Note 1) 1N4148 MBR1045CT (TO-220) MBRB1545CT (TO-263) (Note1) Core: T50-18, L=4m H Turns: 10T, 18 AWG L=2m H 22V, 5%, SMT 1206 size 10V, 5%, SMT 1206 size 324KV, 1%, SMT 0805 size 806V, 1%, SMT 0805 size 90.9KV, 1%, SMT 0805 size 1.24KV, 1%, SMT 0805 size 2.49KV, 1%, SMT 0805 size 4.99KV, 1%, SMT 0805 size 1KV, 1%, SMT 0805 size 1.30KV, 1%, SMT 0805 size 2 KV, 1%, SMT 0805 size 1.21KV,1%, SMT 0805 size 1 KV, 5%, SMT 0805 size 10V, 5%, SMT 0805 size 1KV, 5%, SMT 0805 size 2.4KV, 5%, SMT 0805 size 7.5KV, 5%, SMT 0805 size 6MV1500GX, 1500µF, 6.3V, Elect 6MV1500GX, 1500µF, 6.3V, Elect 1m F, Ceramic, SMT 0805 size 470pF, Ceramic, SMT 0805 size 10pF, Ceramic, SMT 0805 size 6MV1500GX, 1500m F, 6.3V, Elect 6MV1500GX, 1500m F, 6.3V, Elect 1m F, Ceramic, SMT 0805 size 470p, Ceramic, SMT 0805 size For MOSFET, 577002 For Schottky Diode , 577002 For Q1, 507222 (I/O curren<5A) 576602 (I/O current< 3.5A) Manuf IR Motorola IR Motorola Micro Metal (core) Sanyo Sanyo Sanyo Sanyo Sanyo Aavid Aavid Aavid *R4 is a parallel combination of R4A and R4B. Note 1: For the applications where it is desirable to eliminate the heat sink, the IRL3103S for Q2 and MBR1545CT for D2 in TO-263 packages with minimum of 1" square copper pad can be used. Rev. 1.7 07/17/02 www.irf.com 5 IRU3033 TYPICAL APPLICATION 5V to 3.3V for Pentium Application with AGP or Pentium II Application without ATX power supply Dual mode Operation between Switching or Linear mode. R13 12V C9 R9 R6 V12 C8 Drv1 Drv2 VFB2 U1 V1 2 ( S W ) VFB1 C3 R10 R1A Gnd R7 VH Y S T R3 C5 L2 R1B VOUT C7 L1 5V C1 D1 C4 Q2 C2 R4 R2 R5 Figure 4 - This unique application of IRU3033 allows the designer to switch between Linear or Switching mode of operation using a single IC. This circuit has the flexibility to be used for low current operation in Linear mode for cost reasons and yet be able to operate in the Switching mode if the load current increases and the heat generated by the Linear operation will be an issue. The table below describes the components that will be effected for the two modes of operation. Mode of Operation L1 Switching V Linear S L2 D1 C4 C5 R1A R1B R2 R3 R4 R5 R6 R7 V S V O V O V O V O V V V O V V O V V = See parts list for value 6 O V V O S = Short www.irf.com V O O = Open Rev. 1.7 07/17/02 IRU3033 APPLICATION PARTS LIST 5V to 3.3V for Pentium Application with AGP or Pentium II Application without ATX power supply Dual mode Operation between Switching or Linear mode. Ref Desig Description Qty U1 LDO/Switcher IC 1 Q2 MOSFET 1 D1 Schottky Diode 1 L2 Inductor 1 L1 R1A R1B R2 R3 R4 R5 R6 R7 R9 R10 R13 C1, 2 C3 C4 C5 C7 C8 C9 HS1 Inductor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Heat Sink 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 HS2 Heat Sink 1 Part # IRU3033CS (8-Pin SOIC) IRL3303 (TO-220) IRL3103S (TO-263) (Note 1) MBR1045CT (TO-220) MBRB1545CT (TO-263) (Note1) Core: T50-18,L=4mH Turns: 10T, 18 AWG L=2mH 2.4KV, 5%, SMT 1206 size 22V, 5%, SMT 1206 size 10V, 5%, SMT 1206 size 249KV, 1%, SMT 0805 size 1KV, 1%, SMT 0805 size 576V, 1%, SMT 0805 size 180V, 1%, SMT 0805 size 100V, 1%, SMT 0805 size 10V, 5%, SMT 1206 size 1KV, 5%, SMT 1206 size 7.5KV, 5%, SMT 1206 size 6MV1500GX, 1500mF, 6.3V, Elect 1mF, Ceramic, SMT 0805 size 470pF, Ceramic, SMT 0805 size 10pF, Ceramic, SMT 0805 size 6MV1500GX, 1500uF, 6.3V, Elect 1mF, Ceramic, SMT 0805 size 470pF, Ceramic, SMT 0805 size For MOSFET in Switching mode, 577002 For MOSFET in Linear mode: 507222 (3.3V current<5A), 576602 (3.3V current< 3.5A) For Schottky Diode, 577002 Manuf IR IR Motorola Micro Metal (core) Sanyo Sanyo Sanyo Sanyo Aavid Aavid Note 1: For the applications where it is desirable to eliminate the heat sink, the IRL3103S for Q2 and MBR1545CT for D2 in TO-263 packages with minimum of 1" square copper pad can be used. Rev. 1.7 07/17/02 www.irf.com 7 IRU3033 TYPICAL APPLICATION 5V to 3.3V for Pentium application with AGP or Pentium II application without ATX power supply switching mode operation. 12V R9 C8 V12 Drv2 V FB2 Drv1 U1 Gnd V12(SW) V FB1 V HYST C3 R3 C5 L2 R1 VOUT C7 L1 Q2 5V C1 C4 C2 R4 D1 R2 R5 Figure 5 - The circuit in figure 4 is the application of the IRU3033 in a switching mode only. This circuit can be used to generate a low cost 5V to 3.3V for either Pentium application with AGP socket or in Pentium II applications where it is desirable to generate an accurate on board 3.3V supply. Ref Desig Description U1 Q2 LDO/Switcher IC MOSFET Qty 1 1 D1 Schottky Diode 1 L2 Inductor 1 L1 R1 R9 R2 R3 R4 R5 C1, 2 C3 C4 C5 C7 C8 HS1 HS2 Inductor Resistor Resistor Resistor Resistor Resistor Resistor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Heat Sink Heat Sink 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 Part # IRU3033CS (8-Pin SOIC) IRL3303 (TO-220) IRL3103S (TO-263) (Note 1) MBR1045CT (TO-220) MBRB1545CT (TO-263) (Note 1) Core: T50-18, L=4mH Turns: 10T, 18 AWG L=2mH 22V, 5%, SMT 1206 size 10V, 5%, SMT 0805 size 10V, 5%, SMT 1206 size 249KV, 1%, SMT 0805 size 1KV, 1%, SMT 0805 size 576V, 1%, SMT 0805 size 6MV1500GX, 1500mF, 6.3V, Elect 1mF, Ceramic, SMT 0805 size 470pF, Ceramic, SMT 0805 size 10pF, Ceramic, SMT 0805 size 6MV1500GX, 1500mF, 6.3V, Elect 1mF, Ceramic, SMT 0805 size For MOSFET, 577002 For Schottky Diode, 577002 Manuf IR IR Motorola Micro Metal (core) Sanyo Sanyo Sanyo Sanyo Aavid Aavid Note 1: For the applications where it is desirable to eliminate the heat sink, the IRL3103S for Q2 and MBR1545CT for D2 in TO-263 packages with minimum of 1" square copper pad can be used. 8 www.irf.com Rev. 1.7 07/17/02 IRU3033 APPLICATION INFORMATION Introduction The IRU3033 device is an application specific product designed to provide an on board dual supply for the new generation of microprocessors requiring separate Core and I/O supplies. One of the processors fitting this requirement is the new Intel P55C multimedia microprocessor. Intel specifies a Core voltage of 2.8V nominal (±100mV max) with maximum Core supply current of 6A while the I/O supply is set for 3.3V with a maximum I/O current of 0.65A. However, in most applications the I/O regulator also provides the voltage for other IC functions such as the chip set, cache, etc. Typically a low cost solution such as a Low Dropout (LDO) Linear Regulator is selected to provide the I/O supply with the maximum designed current of 3A, keeping the power dissipation and the heat sink to a reasonable size. The Core supply regulator, however, if also selected to be a linear regulator, will be dissipating a maximum of 12.6W [(5V2.8V)X5.7A] of power, which requires a substantial amount of heat sinking and perhaps forced air cooling in order to keep it operational. Some manufacturers suggest using two regulators to current share and therefore distribute the power dissipation equally between the regulators. The problem is that, in order to equally current share you need to sense both currents and force the slave regulator to match the master regulator. This can be done, but at the cost of the circuit complexity and much higher system cost and the total power dissipation is still the same. In fact, if the task is to design a flexible motherboard to accommodate the Cyrix 6X86L or their future MMX processors, then the power dissipation could easily reach 20W or more. At this power dissipation level the choice for a switching regulator approach becomes evident. However, the main reason that designers have always shied away from the switching regulators is their higher price tag and more complex circuit design that is associated with this kind of technique. The IRU3033 device is designed to take advantage of the high efficiency of the switching regulator technique for the Core supply while maintaining the low cost LDO regulator for the I/O supply by offering both control functions in a single 8-pin surface mount package. In fact, as the typical application circuit shows, one can design a complete flexible motherboard using the IRU3033 and a few external components yielding a very low component count switching regulator and with an addition of a low cost pass transistor for the I/O supply provide a complete dual supply power solution. Rev. 1.7 07/17/02 LDO Section The output voltage of the LDO regulator is externally programmable via 2 external resistors from 1.25V to 5V. The internal voltage reference of the LDO regulator is set to 1.25V and the output of the regulator can be programmed using the following formula: VOUT = (1 + R1/R2) 3 VREF Where: VREF = 1.25V Typical R1 = Resistor connected from V OUT to the V FB2 pin of IRU3033. R2 = Resistor connected from VFB2 pin to Gnd. The IRU3033 requires the use of an output capacitor as part of the frequency compensation in order to be stable. Typical designs for the microprocessor applications use standard electrolytic capacitors with typical ESR in the range of 50 to 100mV and an output capacitance of 500 to 1000mF. Fortunately as the capacitance increases, the ESR decreases resulting in a fixed RC time constant. The IRU3033 takes advantage of this phenomena in making the overall regulator loop stable. For most applications a minimum of 100mF aluminum electrolytic capacitor such as Sanyo, MVGX series, Panasonic FA series or Nichicon PL series insures both stability and good transient response. An external filtering is suggested as shown in the application circuit that reduces the switching ripple that might show in the output of the LDO regulator. Switching Controller Operation The operation of the switching controller is as follows: After the power is applied, the output drive (Drv1) goes to 100% duty cycle and the current in the inductor charges the output capacitor causing the output voltage to increase. When output reaches a pre-programmed set point the feedback pin (V FB1) exceeds 1.25V causing the output drive to switch low and the VHYST pin to switch high which jumps the feedback pin higher than 1.25V resulting in a fixed output ripple which is given by the following equation: DVo = (Rt/RB)311 Where: Rt = Top resistor of the output divider, resistor connected from VOUT to the VFB1 pin of IRU3033. RB = Bottom resistor of the divider, resistor connected from VFB1 pin to VHYST pin. www.irf.com 9 IRU3033 For example, if Rt=1K and RB=422K, then the output ripple is: DVo = (1/422)311 = 26mV The advantage of fixed output ripple is that when the output voltage changes from 2V to 3.5V, the ripple voltage remains the same which is important in meeting the Intel maximum tolerance specification. Switcher Output Voltage Setting The output voltage of the switcher can be set using the following equations: Frequency Calculation The IRU3033 frequency of operation is calculated using the following formula: Fs = [(Vo3(1 - D)3ESR)] / (L3DVo) (MHz) Where: Vo = Output voltage (V) D = Duty cycle ESR = Output capacitor ESR (V) L = Output inductance (mH) DVo = Output ripple voltage (V) For our example: Assuming, Vo=3.38V and the selected output ripple is ≈ 1.3%(44mV) of the output voltage, a set of equations are derived that selects the resistor divider and the hysteresis resistor. D ≈ (Vo + Vf) / VIN Where: Vf = Forward voltage drop of the Schottky diode. D = (3.38 + 0.5) / 5 = 0.78 Assuming, Rt=1KV , 1%: The ESR=18mV for 2 of the Sanyo 1500mF, 6MV1500GX caps. If L=3.5mH then, Fs is calculated as follows: RH = (113Rt) / DV Where: Rt = Top resistor of the resistor divider. RH = Hysteresis resistor connected between pins 3 and 4 of the IRU3033. DVo = Selected output ripple (typically 1% to 2% of output voltage). Fs = [(3.38 3 (1 - 0.78) 3 0.018)] = 0.087MHz (3.5 3 0.044) Fs = 87KHz Assuming, DVo=44mV: RH = (1131000) / 0.044 = 250KV Select RH = 249KV, 1% The bottom resistor of the divider is then calculated using the following equations: RB = Rt / X Where: RB = Bottom resistor of the divider VREF = 1.25V typical X = [(Vo + DVo )/VREF] - 1 2 X = [(3.38 + 0.044 )/1.25] - 1 = 1.72 2 RB = 1000 / 1.72 = 580V Select RB = 576V, 1% IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105 TAC Fax: (310) 252-7903 Visit us at www.irf.com for sales contact information Data and specifications subject to change without notice. 02/01 10 www.irf.com Rev. 1.7 07/17/02 IRU3033 (S) SOIC Package 8-Pin Surface Mount, Narrow Body H A B C E DETAIL-A PIN NO. 1 L D DETAIL-A 0.386 0.015 x 458 T K I F J G 8-PIN SYMBOL A B C D E F G H I J K L T MIN MAX 4.80 4.98 1.27 BSC 0.53 REF 0.36 0.46 3.81 3.99 1.52 1.72 0.10 0.25 78 BSC 0.19 0.25 5.80 6.20 08 88 0.41 1.27 1.37 1.57 NOTE: ALL MEASUREMENTS ARE IN MILLIMETERS. Rev. 1.7 07/17/02 www.irf.com 11 IRU3033 PACKAGE SHIPMENT METHOD PKG DESIG S PACKAGE DESCRIPTION PIN COUNT PARTS PER TUBE PARTS PER REEL T&R Orientation 8 95 2500 Fig A SOIC, Narrow Body 1 1 1 Feed Direction Figure A IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105 TAC Fax: (310) 252-7903 Visit us at www.irf.com for sales contact information Data and specifications subject to change without notice. 02/01 12 www.irf.com Rev. 1.7 07/17/02