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IRU1260
DUAL DROPOUT POSITIVE ADJUSTABLE REGULATOR FEATURES
Guaranteed <1.3V Dropout (output Guaranteed <0.6V Dropout (output Fast Transient Response Voltage Reference Initial Accuracy Built Thermal Shutdown
IRU1260 uses proprietary process combines dual dropout adjustable output regulator single package with output having minimum other having output current capability. This product specifically designed provide well regulated supplies voltage such 3.3V 1.5V 2.5V supplies GTL+ termination clock Pentium applications. Other applications include cost dual supply processors such Intel P55Cwhere 2.8V needed Core supplies from input.
APPLICATIONS
Providing single package solution GTL+ High Speed Termination Dual supply P55Capplications
TYPICAL APPLICATION
3.3V
Vout1
2.5V
Vout2
1.5V
IRU1260 US1260
Vfb2 Vfb1 Vctrl
1260app7-1.0
Typical application IRU1260 Pentium design with 1.5V output providing GTL+ termination while 2.5V supplies clock chip
Notes: Pentium trademark Intel Corp. P55C trademark Intel Corp.
PACKAGE ORDER INFORMATION
(°C) 7-PIN PLASTIC TO-220(T) IRU1260CT 7-PIN PLASTIC TO-263(M) IRU1260CM 7-PIN PLASTIC ULTRA THIN-PAK(P) IRU1260CP
Rev. 3/22/99
IRU1260
ABSOLUTE MAXIMUM RATINGS
Input Voltage Power Dissipation Internally Limited Storage Temperature Range -65° 150° Operating Junction Temperature Range 150°
PACKAGE INFORMATION
7-PIN PLASTIC TO-220
FRONT VIEW
7-PIN PLASTIC TO-263
FRONT VIEW Vout1 Vout2 Vfb2 Vfb1 Vctrl
7-PIN ULTRA THIN-PAK
FRONT VIEW
Vout1 Vout2 Vfb2 Vfb1 Vctrl
Vout1 Vout2 Vfb2 Vfb1 Vctrl
=2.7°C/W =60°C/W
=30°C/W 1"sq
=30°C/W 1"sq
ELECTRICAL SPECIFICATIONS
Unless otherwise specified, these specifications apply over, Cin=1µF, Cout =10µF, Tj=0 150°C. Typical values refer Tj=25°C. Ifl=6A output Ifl=1A output Vfb=Vo both outputs. Vctrl=Vin=3.3V. PARAMETER Vctrl Input Voltage Reference Voltage Line Regulation Load Regulation (note Dropout Voltage (output (Note Dropout Voltage (output (Note Current Limit (output Current Limit (output Thermal Regulation Ripple Rejection Vref TEST CONDITION Io=10mA, Tj=25°C 1.188 1.200 Io=10mA 1.176 1.200 Io=10mA, Vout+1.3V<Vin=Vctrl<7V 10mA<Io<Ifl Io=4A, Vctrl=4.75V, Vin=3.3V Io=3A, Vctrl=4.75V, Vin=3.3V Io=2A, Vctrl=4.75V, Vin=3.3V 0.35 Io=1A, Vctrl=4.75V, Vin=3.3V Io=1A, Vctrl=Vin=4.75V dVo=100mV dVo=100mV 30mS pulse, Io=Ifl 0.01 f=120HZ, Co=25µF Tantalum Io=0.5*Ifl Io=10mA 0.02 Io=10mA Ta=125°C, 1000 Ta=25°C 10hz<f<10khz 0.003 1.212 1.224 UNITS
ICL2 ICL1
0.02
Feedback Input Current Temperature Stability Long Term Stability Output Noise Minimum Load Current (Note
Note duty cycle pulse testing with Kelvin connections required order maintain accurate data. Note Dropout voltage defined minimum differential voltage between required maintain regulation Vout measured when output voltage drops below nominal value.
Note Minimum load current defined minimum current required output order output voltage maintain regulation. Typically resistor dividers selected such that automatically maintains this current.
Rev. 3/22/99
IRU1260
DESCRIPTIONS
SYMBOL
Vfb2 Vfb1 Vout2 Vout1
resistor divider from this Vout ground sets output voltage. application divider setting 1.5V output. resistor divider from this Vout ground sets output voltage. application divider setting 2.5V output. output (high current) regulator. minimum 100µF capacitor must connected from this ground insure stability. output (low current) regulator. minimum 100µF capacitor must connected from this ground insure stability. power input regulator. Typically large storage capacitor connected from this ground insure that input voltage does below minimum dropout voltage during load transient response. This must always higher than both Vout pins amount dropout voltage. (see datasheet) order device regulate properly.) This connected GND. also package. control input regulator. This resistor connected supply provide base current pass transistor both regulators. This allows regulator have very dropout voltage which allows generate well regulated 2.5V supply from 3.3V input. high frequency, capacitor connected between this insure stability.
Vctrl
BLOCK DIAGRAM
Vctrl Vfb1 Vout1
THERMAL SHUTDOWN
1.20V
Vfb2
1260blk1-1.1
Vout2
Figure Simplified block diagram IRU1260
Rev. 3/22/99
IRU1260
APPLICATION INFORMATION
Introduction
IRU1260 dual adjustable Dropout (LDO) regulator packaged 7-pin TO-220 which easily programmed with addition external resistors voltages within range 1.20 This voltage regulator designed specifically applications that require separate regulators such Intel Pentium IIprocessors requiring 1.5V supplies, eliminating need second regulator which results lower overall system cost. When Vctrl connected supply which least higher than Vin, dropout voltage improves which makes ideal applications requiring less than standard 1.3V dropout given products such IRU10XX series. IRU1260 also provides accurate 1.20V voltage reference common both regulators programming each output voltage. Other features device include: fast response sudden load current changes, such GTL+ termination application Pentium family microprocessors. IRU1260 also includes thermal shutdown protection protect device overload condition occurs. IRU1260 keeps constant 1.20V between ground pin. placing resistor across these pins constant current flows through adding current into resistor producing voltage equal (1.2/R1)*R2 IFB* which will added 1.20V output voltage shown above equation. Since input bias current amplifier (IFB) only 0.02µA typically, adds very small error output voltage most applications ignored. example, typical 1.5V GTL+application R1=10.2k R2=2.55k error Iadj only 0.05mV which less than 0.004% nominal point. effective input impedance seen feedback pins IIR2) must always higher than 1.8k order regulator start properly.
Load Regulation
Since IRU1260 does provide separate ground reference voltage, possible provide true remote sensing output voltage load. Figure shows that best load regulation achieved when bottom side resistor connected directly ground IRU1260 (preferably device) side resistor connected load. fact, connected load side, effective resistance between regulator load gained factor (1+R2/R1), effective resistance will Rp(eff)=Rp*(1+R2/R1). important note that high current applications, this represent significant percentage overall load regulation must keep path from regulator load short possible minimize this effect.
Output Voltage Setting
IRU1260 programmed voltages range 1.20V 5.5V with addition external resistors according following formula:
VOUT VREF Where: Wehre VREF 1.20V Typically Typically
0.02µA Typical shown Figure
Vout
US1260 IRU1260
Vctrl
Vctrl
Vout
Vout
IRU1260 US1260
Vctrl
Vctrl Vref
1260app2-1.0 PARASITIC LINE RESISTANCE
1260app3-1.1
Figure Typical application IRU1260 programming output voltage. (Only output shown here)
Figure Schematic showing connection best load regulation. (Only output shown here)
Rev. 3/22/99
IRU1260
Stability
IRU1260 requires output capacitor part frequency compensation order make regulator stable. Typical designs microprocessor applications standard electrolytic capacitors with typical range 100m output capacitance 1000µF. Fortunately capacitance increases, decreases resulting fixed time constant. IRU1260 takes advantage this phenomena making overall regulator loop stable. most applications minimum 100µF aluminum electrolytic capacitor with maximum such Sanyo, MVGX series, Panasonic series well Nichicon series insures both stability good transient response. IRU1260 also requires ceramic capacitor connected from Vctrl 0.1W resistor series with ctrl order further insure stability. Thermal Design IRU1260 incorporates internal thermal shutdown that protects device when junction temperature exceeds maximum allowable junction temperature. Although this device operate with junction temperatures range 150°C, recommended that selected heat sink chosen such that during maximum continuous load operation junction temperature kept below this number. examples given which shows steps selecting proper regulator heat sink driving Pentium processor GTL+ termination resistors Clock using IRU1260 TO-220 TO-263 packages. Example Assuming following specifications: 3.3V VOUT VOUT IOUT IOUT
Select package from datasheet record junction case Tab) thermal resistance. Selecting TO-220 package gives
=27°
Assuming that heat sink black anodized, calculate maximum heat sink temperature allowed: Assume 0.05 °C/W (heat-sink-to-case thermal resistance black anodized) 0.05 107.4 With maximum heat sink temperature calculated previous step, heat-sink-to-air thermal resistance calculated follows: 107.4 72.4 72.4 7.24
Next, heat sink with lower than calculated step must selected. this simply look graphs "Heat Sink Temp Rise Above Ambient" "Power Dissipation" select heat sink that results lower temperature rise than calculated previous step. following heat sinks from AAVID Thermaloy meet this criteria.
Flow (LFM) 7021B 7020B 6021PB 7173D 7141D 593101B 551002B 534202B 577102B 576802B
Thermalloy AAVID
5.4A
Note: further information regarding above companies their latest product offering application support contact your local representative numbers listed below: Thermalloy AAVID (214) 243-4321 (603) 528-3400
steps selecting proper heat sink keep junction temperature below 135°C given Calculate maximum power dissipation using: IOUT1 VOUT1) IOUT2 VOUT2) (3.3 1.5)
Rev. 3/22/99
IRU1260
Example Assuming following specifications: 3.3V VOUT VOUT IOUT IOUT
this application, IRU1260 used card convert 3.3V supply 2.7V power Intel chip rather than conventional which 1.5V minimum dropout spec must supply achieve same result. difference substantial decrease power dissipation shown below. maximum power dissipation chip 5.8W, which 2.7V results Io=5.8/2.7=2.15A Using standard LDO, power dissipated device Pd=(Vin Vo)*Io=(5-2.7)*2.15=4.94W
1.5A
steps selecting proper heat sink keep junction temperature below 135° given Calculate maximum power dissipation using: IOUT1 VOUT1) IOUT2 VOUT2) Using surface mount TO-263 package with junction thermal resistance results Tj=Pd*ja Ta=(4.94)(25) 25=148 This very close thermal shutdown Using 1260, power dissipated device drastically reduced using 3.3V supply instead Pd=(Vin Vo)*Io=(3.3-2.7)*2.15=1.3W Using surface mount TO-263 package with junction thermal resistance results Tj=Pd*ja Ta=(1.3)(25) 25=57 reduction junction temperature. 2.5) 1.5) 2.86 Assuming TO-263 surface mount package, junction ambient thermal resistance package
square area
maximum junction temperature device calculated using equation below: 2.86 Since this lower than selected 135°C maximum junction temperature (150°C thermal shutdown device), TO-263 package suitable package application. Layout Consideration IRU1260 like other high speed linear regulators need properly laid insure stable operation. most important component output capacitor, which needs placed close output connected this using plane connection with inductance path. IRU1260 Ultra LDO, Single Output Application IRU1260 also used single supply applications where difference between input output much lower than standard 1.5V dropout that obtainable with standard devices. schematic Figure shows application IRU1260 single supply with second being disabled.
Rev. 3/22/99
IRU1260
TYPICAL APPLICATION
PENTIUM APPLICATION
3.3V
Vout1
2.5V
Vout2
1.5V
US1260 IRU1260
Vfb2 Vfb1 Vctrl
1260app7-1.0
Figure Typical application IRU1260 Pentium design with 1.5V output providing GTL+ termination while 2.5V supplies clock chip.
Notes: Pentium trademark Intel Corp.
Desig R2,R4
Description Dual Regulator Capacitor Capacitor Capacitor Capacitor Resistor Resistor Resistor Resistor Heat Sink
Part
Manuf
IRU1260CM Elect, 680µF, EEUFA1A681L Panasonic Elect, 220µF, 6.3V, ECAOJFQ221 Panasonic Ceramic, 0.1µF, SMT, 0805 Panasonic Elect,100µF, 6.3V, ECAOJFQ101 Panasonic 11k, SMT, 0805 Panasonic 10.2k, SMT, 0805 Panasonic 2.55k, SMT, 0805 Panasonic SMT, 0805 Panasonic Square Copper area Iout2<1.7A Iout1<0.2A. Iout2<3A Iout1<0.5A, IRU1260CT Thermalloy 6030B
Rev. 3/22/99
IRU1260
TYPICAL APPLICATION
RAMBUS APPLICATION
Vout1
2.5V
Vout2
3.3V
IRU1260 US1260
Vfb2 Vfb1 Vctrl
1260app6-1.0
Figure Typical application IRU1260 Rambusdesign with 2.5V output providing memory termination while 3.3V supplies board logic
Note: Rambus trademark Rambus Corp.
Desig R2,R4
Description Dual Regulator Capacitor Resistor Resistor Resistor Heat Sink
Part Manuf IRU1260CM Elect, 220µF, 6.3V, ECAOJFQ221 Panasonic 11k, SMT, 0805 Panasonic 10.2k, SMT, 0805 Panasonic 17.8k, SMT, 0805 Panasonic Square Copper area Iout2<1.2A Iout1<0.5A. Iout2<3A Iout1<0.5A, Thermalloy 6030B
3-10
Rev. 3/22/99
IRU1260
TYPICAL APPLICATION
INTEL I740 GRAPHICS CHIP APPLICATION
3.3V
Vout1
Vout2
2.7V
IRU1260
Vfb2 Vfb1 Vctrl
1260app8-1.0
Figure Typical application IRU1260 provide 2.7V from 3.3V Intel graphics chip
Desig
Description Dual Regulator Capacitor Capacitor Capacitor Resistor Resistor Resistor
Part IRU1260CM Elect, 680µF, EEUFA1A681L Ceramic, 0.1µF, SMT, 0805 Elect,100µF, 6.3V, ECAOJFQ101 10.2k, SMT, 0805 12.7k, SMT, 0805 SMT, 0805
Manuf Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic
Rev. 3/22/99
3-11
IRU1260
Notes
3-12
Rev. 3/22/99

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