C2 100uF. Figure 1 - Typical application of IRU1150 in a 3.3V to 2.7V for I740 chip. PACKAGE ORDER INFORMATION. Basic Part (Non-Lead Free)

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Cecil Harold Evans
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1 ata Sheet No. 99 rev IRU0(bF) FTURS 0.7 ropout at Fast Transient Response % oltage Reference Initial ccuracy uilt-in Thermal Shutdown ITIONS. to.7 Intel I70 hip Set UTR OW ROOUT OSITI JUST RUTOR SRITION The IRU0 is a regulator with extremely low dropout voltage using a proprietary bipolar process that achieves comparable equivalent on-resistance to that of discrete OSFTs. This product is specifically designed to provide well regulated supply for applications requiring.8 or lower voltages from. TX power supplies where high efficiency of a switcher can be achieved without the cost and complexity associated with switching regulators. One such application is the new graphic chip sets that require anywhere from. to.7 supply such as the Intel I70 chip set. TYI ITION. 00uF IRU0.7 R 0 R 8 00uF 00uF Figure - Typical application of IRU0 in a. to.7 for I70 chip. ORR INFORTION asic art (Non-ead Free) TJ ( ) -IN STI -IN STI 8-IN STI TO-6 () Ultra Thin-ak T () SOI (S) 0 To IRU0 IRU0 IRU0S eadfree art TJ ( ) -IN STI -IN STI 8-IN STI TO-6 () Ultra Thin-ak T () SOI (S) 0 To Not available Not available IRU0SbF

2 IRU0(bF) SOUT XIU RTINS Input oltage ()... 7 ontrol Input oltage ()... ower issipation... Internally imited Storage Temperature Range To 0 Operating Junction Temperature Range... 0 To 0 INFORTION -IN STI TO-6 () -IN STI UTR TIN- T () 8-IN STI SOI (S) Tab is FRONT IW Tab is FRONT IW TO IW θj= /W for 0." square pad θj= /W for 0." square pad θj= /W for " Sq pad area TRI SIFITIONS Unless otherwise specified, these specifications apply over IN=µF, OUT=0µF, and TJ=0 to. Typical values refer to TJ=. =. RTR SY TST ONITION IN TY X UNITS Reference oltage RF..0.7 ine Regulation m oad Regulation (Note ) - + m ropout oltage (Note ) ( - ) ropout oltage (Note ) ( - ) urrent imit inimum oad urrent (Note ) Thermal Regulation Ripple Rejection ontrol in urrent ust in urrent IJ =.7 to, =.0 to., Io=0m to, J=0 =. to 7, =.7 to., Io=0m, J=0 =.7, =., Io=0m to, J=0 J=0 for all conditions below: =.0, Io=. =.0, Io= =.0, Io= J=0 for all conditions below: =.7, Io=. =.7, Io= =.7, Io= =.7, =.0, o=00m, J=0 =, =., J=0 0ms ulse =, =, Io=, J=0, TJ=, RI= at 0z J=0 for all below conditions: =.7, =.0, Io=. =.7, =.0, Io= =.7, =.0, Io= =.7, =.0, J= m %/W d m µ

3 IRU0(bF) Note : ow duty cycle pulse testing with elvin connections is required in order to maintain accurate data. Note : ropout voltage is defined as the minimum differential between and required to maintain regulation at. It is measured when the output voltage drops % below its nominal value. Note : inimum load current is defined as the minimum current required at the output in order for the output voltage to maintain regulation. Typically the resistor dividers are selected such that it automatically maintains this current. IN SRITIONS IN # IN SYO IN SRITION This pin is the positive side of the reference which allows remote load sensing to achieve excellent load regulation. resistor divider from this pin to the pin and ground sets the output voltage. The output of the regulator. minimum of 0µF capacitor must be connected from this pin to ground to insure stability. This pin is the supply pin for the internal control circuitry as well as the base drive for the pass transistor. This pin must always be higher than the pin in order for the device to regulate. (See specifications) The input pin of the regulator. Typically a large storage capacitor is connected from this pin to ground to insure that the input voltage does not sag below the minimum drop out voltage during the load transient response. This pin must always be higher than in order for the device to regulate. (See specifications) O IR +. + URRNT IIT TR SUTOWN Figure - Simplified block diagram of the IRU0.

4 IRU0(bF) ITION INFORTION Introduction The IRU0 adjustable regulator is a five-terminal device designed specifically to provide extremely low dropout voltages comparable to the N type without the disadvantage of the extra power dissipation due to the base current associated with N regulators. This is done by bringing out the control pin of the regulator that provides the base current to the power NN and connecting it to a voltage that is grater than the voltage present at the pin. This flexibility makes the IRU0 ideal for applications where dual inputs are available such as a computer mother board with an TX style power supply that provides and. to the board. One such application is the new graphic chip sets that require anywhere from. to.7 supply such as the Intel I70 chip set. The IRU0 can easily be programmed with the addition of two external resistors to any voltages within the range of. to.. nother major requirement of these graphic chips such as the Intel I70 is the need to switch the load current from zero to several amps in tens of nanoseconds at the processor pins, which translates to an approximately 00 to 00ns of current step at the regulator. In addition, the output voltage tolerances are also extremely tight and they include the transient response as part of the specification. The IRU0 is specifically designed to meet the fast current transient needs as well as providing an accurate initial voltage, reducing the overall system cost with the need for fewer number of output capacitors. nother feature of the device is its true remote sensing capability which allows accurate voltage setting at the load rather than at the device. Output oltage Setting The IRU0 can be programmed to any voltages in the range of. to. with the addition of R and R external resistors according to the following formula: = RF + ( ) R R +IJ R Where: RF =. Typically IJ = 0µ Typically R and R as shown in Figure : IRU0 RF IJ = 0u Figure - Typical application of the IRU0 for programming the output voltage. in IRU0 R R R R The IRU0 keeps a constant. between the pin and the J pin. y placing a resistor R across these two pins and connecting the and pin together, a constant current flows through R, adding to the Iadj current and into the R resistor producing a voltage equal to the (./R) R + IJ R. This voltage is then added to the. to set the output voltage. This is summarized in the above equation. Since the minimum load current requirement of the IRU0 is 0m, R is typically selected to be a Ω resistor so that it automatically satisfies this condition. Notice that since the IJ is typically in the range of 0µ it only adds a small error to the output voltage and should be considered when very precise output voltage setting is required. oad Regulation Since the IRU0 has separate pins for the output () and the sense (), it is ideal for providing true remote sensing of the output voltage at the load. This means that the voltage drops due to parasitic resistance such as traces between the regulator and the load are compensated for using remote sensing. Figure shows a typical application of the IRU0 with remote sensing. R Figure - Schematic showing connection for best load regulation.

5 IRU0(bF) Stability The IRU0 requires the use of an output capacitor as part of the frequency compensation in order to make the regulator stable. Typical designs for the microprocessor applications use standard electrolytic capacitors with typical SR in the range of 0 to 00mΩ and an output capacitance of 00 to 000µF. Fortunately as the capacitance increases, the SR decreases resulting in a fixed R time constant. The IRU0 takes advantage of this phenomena in making the overall regulator loop stable. For most applications a minimum of 00µF aluminum electrolytic capacitor such as Sanyo, X series, anasonic F series as well as the Nichicon series insures both stability and good transient response. Thermal esign The IRU0 incorporates an internal thermal shutdown that protects the device when the junction temperature exceeds the allowable maximum junction temperature. lthough this device can operate with junction temperatures in the range of 0, it is recommended that the selected heat sink be chosen such that during maximum continuous load operation the junction temperature is kept below this number. The example below shows the steps in selecting the proper surface mount package. ssuming, the following conditions: =.7 =. = IOUT = ( vg) alculate the maximum power dissipation using the following equation: = IOUT ( - )+ IOUT ( 60 ) ( ) ( - ) = (. -.7)+ ( -.7) =.8W 60 Using table below select the proper package and the amount of copper board needed. kg opper θj( /W) ax d ax d rea (T= ) (T= ) TO-6."X.".W.6W TO-6.0"X.0" 0.7W.0W TO-6 0.7"X0.7".W.6W TO-6 ad Size.W.0W SO-8.0"X.0".0W.6W Note: bove table is based on the maximum junction temperature of. s shown in the above table, any of the two packages will do the job. For low cost applications the SOI 8-pin package is recommended.

6 IRU0(bF) () TO-6 ackage -in U S N R SYO N R S U IN X RF 7.7 RF NOT: SURNTS R IN IITRS. 6

7 IRU0(bF) () Ultra Thin-ak T -in U N R SYO N R U IN X NO NO 7.9 NO NOT: SURNTS R IN IITRS. 7

8 IRU0(bF) (S) SOI ackage 8-in Surface ount, Narrow ody TI- IN NO. 0.8±0.0 x TI- T F I J SYO F I J T 8-IN IN X.98.7 S 0. RF 7 S NOT: SURNTS R IN IITRS. 8

9 IRU0(bF) SINT TO SI SRITION IN OUNT RTS R TU RTS R R T & R Orientation TO Fig Ultra Thin-ak T 7 00 Fig S SOI, Narrow ody Fig Feed irection Figure Feed irection Figure Feed irection Figure IR WOR QURTRS: ansas St., l Segundo, alifornia 90, US Tel: (0) -70 T Fax: (0) -790 isit us at for sales contact information ata and specifications subject to change without notice. 8/8/00 9

C2 10uF. Figure 1 - Typical application of IRU1175. TJ ( C) 5-PIN PLASTIC 5-PIN PLASTIC TO-263 (M) Ultra Thin-Pak TM (P) 0 To 125 IRU1175CM IRU1175CP

C2 10uF. Figure 1 - Typical application of IRU1175. TJ ( C) 5-PIN PLASTIC 5-PIN PLASTIC TO-263 (M) Ultra Thin-Pak TM (P) 0 To 125 IRU1175CM IRU1175CP FETURES 0. Dropout at 7. (Equivalent of 67mΩ) Fast Transient Response % oltage Reference Initial ccuracy Built-In Thermal Shutdown LICTIONS. to.7 Intel I70 Chip Set TYICL LICTION Data Sheet No. D9 IRU7