7.5A ULTRA DROPOUT POSITIVE ADJUSTABLE REGULATOR 0.5V Dropout 7.5

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7.5A ULTRA DROPOUT POSITIVE ADJUSTABLE REGULATOR 0.5V Dropout 7.5

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IRU1175
7.5A ULTRA DROPOUT POSITIVE ADJUSTABLE REGULATOR
0.5V Dropout 7.5A (Equivalent 67m) Fast Transient Response Voltage Reference Initial Accuracy Built-in Thermal Shutdown
DESCRIPTION
IRU1175 7.5A regulator with extremely dropout voltage using proprietary bipolar process that achieves comparable equivalent resistance that discrete MOSFETs. This product specifically designed provide well regulated supply applications requiring very dropout such 2.8V from 3.3V power supplies where same efficiency switcher achieved without cost complexity associated with switching regulators. such application graphic chipsets that requires 2.7V supply such Intel I740 chipset.
APPLICATIONS
3.3V 2.7V Intel I740 chipset
TYPICAL APPLICATION
3.3V
100uF
Vctrl
10uF 100uF
IRU1175
Vout Vsense
2.7V
1175app1-1.0
Typical application IRU1175
PACKAGE ORDER INFORMATION
(°C) 5-PIN PLASTIC 5-PIN PLASTIC 8-PIN PLASTIC TO-263 ULTRA THIN-PAK SOIC IRU1175CM IRU1175CP IRU1175CS
Rev. 11/29/99
2-79
IRU1175
ABSOLUTE MAXIMUM RATINGS
Input Voltage Control Input Voltage ctrl) Power Dissipation. Internally Limited Storage Temperature Range -65° 150° Operating Junction Temperature Range 150°
PACKAGE INFORMATION
8-PIN PLASTIC SOIC
VIEW
5-PIN PLASTIC TO-263
FRONT VIEW
5-PIN PLASTIC ULTRA THIN-PAK
FRONT VIEW
Vctrl Vsense
Vout Vout Vout Vout
Vctrl Vout Vsense
Vctrl Vout Vsense
JA=55°C/W area
JA=35°C/W 0.5" square
JA=35°C/W 0.5" square
ELECTRICAL SPECIFICATIONS
Unless otherwise specified, these specifications apply over, Cin=1µF, Cout =10µF, Tj=0 125°C. Typical values refer Tj=25°C. =Vsense. PARAMETER Reference Voltage Vref TEST CONDITION Vctrl=2.75V, Vin=2V, Io=10mA 1.243 Tj=25, Vadj=0V Vctrl=2.7to12V, Vin=2.05V 5.5V, 1.237 Io=10mA 7.5A, Vadj=0V Vctrl=2.5Vto7V, Vin=1.75Vto5.5V Io=10mA Vadj=0V Vctrl=2.75V, Vin=2.1V, Io=10mA 7.5A, Vadj=0V Vadj=0V conditions below. Vin=2.05V, Io=1.5A Vin=2.05V, Io=3A Vin=2.05V, Io=5A Vin=2.05V, Io=7.5A Vadj=0V conditions below. Vctrl=2.75V, Io=1.5A Vctrl=2.75V, Io=3A Vctrl=2.75V, Io=5A Vctrl=2.75V, Io=7.5A Vctrl=2.75V, Vin=2.05V, dVo=100mV Vadj=0V Vctrl=5V, Vin=3.3V, Vadj=0V 30mS Pulse Vctrl=5V, Vin=5V, Io=3A,Vadj=0V Tj=25, Vripple=1Vpp 120Hz 1.250 1.250 1.257 1.263 UNITS
Line Regulation Load Regulation (note Dropout Voltage (note ctrl Vout
0.95 1.00 1.05 1.15 0.100 0.200 0.330 0.500 0.01
1.30 0.130 0.260 0.430 0.650
Dropout Voltage (note Vout
Current Limit Minimum Load Current (note Thermal Regulation Ripple Rejection
0.02
2-80
Rev. 11/29/99
IRU1175
ELECTRICAL SPECIFICATIONS
PARAMETER
Control Current
TEST CONDITION
Vadj=0V below conditions. Vctrl=2.75V, Vin=2.05V, Io=1.5A Vctrl=2.75V, Vin=2.05V, Io=3A Vctrl=2.75V, Vin=2.05V, Io=5A Vctrl=2.75V, Vin=2.05V, Io=7.5A
UNITS
Adjust Current
Iadj
Vctrl=2.75V, Vin=2.05V, Vadj=0V
Note duty cycle pulse testing with Kelvin connections required order maintain accurate data. Note Dropout voltage defined minimum differential 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.
DESCRIPTIONS
SYMBOL DESCRIPTION Vsense This positive side reference which allows remote load sensing achieve excellent load regulation. resistor divider from this Vout ground sets output voltage. output regulator. minimum 10µF capacitor must connected from this ground insure stability. This supply internal control circuitry well base drive pass transistor. This must always higher than Vout order device regulate. (see specifications) input regulator. Typically large storage capacitor connected from this ground insure that input voltage does below minimum drop voltage during load transient response. This must always higher than Vout order device regulate. (see specifications)
Vout
Vctrl
Rev. 11/29/99
2-81
IRU1175
BLOCK DIAGRAM
Vout
Vctrl
1504
Vsense
1.25V CURRENT LIMIT
THERMAL SHUTDOWN
1175blk1-1.0
Figure Simplified block diagram IRU1175
APPLICATION INFORMATION
Introduction IRU1175 adjustable regulator five-terminal device designed specificaly provide extremely dropout voltages comparable type without disadvantage extra power dissipation base current associated with regulators.This done bringinging control regulator that provides base current power connecting voltage that grater than voltage present pin.This flexibility makes IRU1175 ideal applications where dual inputs available such computer motherboard with style power supply that provides 3.3V board. such application graphic chipsets that require anywhere from 2.4V 2.7V supply such Intel I740 chipset. IRU1175 easily programmed with addition external resistors voltages within range 1.25 Another major requirement these graphic chips need switch load current from zero several amps tens nanoseconds processor pins, which translates approximately 500nS current step regulator. addition, output voltage tolerances also extremely tight they include transient response part specification.
IRU1175 specifically designed meet fast current transient needs well providing accurate initial voltage, reducing overall system cost with need fewer number output capacitors. Another feature device true remote sensing capability which allows accurate voltage setting load rather than device. Output Voltage Setting IRU1175 programmed voltages range 1.25V 5.5V with addition external resistors according following formula: VOUT VREF IADJ Where: =125 Wehre VREF=1.25V Typically IADJ=50µA Typically shown Figure
Vout
Vout
IRU1175 Vctrl
Vctrl Vsense Vref
IAdj 50uA
1175app2-1.0
Figure Typical application IRU1175 programming output voltage
2-82
Rev. 11/29/99
IRU1175
IRU1175 keeps constant 1.25V between Vsense Vadj pin. placing resistor across these pins connecting Vsense Vout together, constant current flows through adding Iadj current into resistor producing voltage equal (1.25/R1)*R2 *R2. This voltage then added 1.25V output voltage. This summarized above equation. Since minimum load current requirement IRU1175 10mA, typically selected resistor that automatically satisfies this condition. Notice that since Iadj typically range 50µA only adds small error output voltage should considered when very precise output voltage setting required. Load Regulation Since IRU1175 separate pins output sense sense), ideal providing true remote sensing output voltage load. This means that voltage drops parasitic resistance such traces between regulator load compensated using remote sensing. Figure shows typical application IRU1175 with remote sensing.
Vout
most applications minimum 100µF aluminum electrolytic capacitor such Sanyo, MVGX series, Panasonic series well Nichicon series insures both stability good transient response. Thermal Design IRU1175 incorporates internal thermal shutdown that protects device when junction temperature exceeds allowable maximum junction temperature. Although this device operate with junction temperatures range 150°C, recommended that selected heat sink chosen such that during maximum continuos load operation junction temperature kept below this number. example below shows steps selecting proper surface mount package. Assuming, following conditions: Vout =2.7V Vin=3.3V Vctrl=5V Iout Calculate maximum power dissipation using following equation: Pd=Iout in-V (Iout /60)*(V ctrl Vout Pd=2*(3.3-2.7) (2/60)*(5-2.7)=1.28
IRU1175 Vctrl
Vctrl Vsense
Using table below select proper package amount copper board needed. TO-263 TO-263 TO-263 TO-263 SO-8 Copper 1.4"X1.4" 1.0"X1.0" 0.7"X0.7" Size 1.0"X1.0" JA(°C/W) Area (Ta=25°C) 4.4W 3.7W 3.1W 2.4W 2.0W (Ta=45°C) 3.6W 3.0W 2.6W 2.0W 1.63W
1175app3-1.0
Figure Schematic showing connection best load regulation Stability IRU1175 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. IRU1175 takes advantage this phenomena making overall regulator loop stable.
Note: Above table based maximum junction temperature 135°C. shown above table, packages will job. cost applications SO-8 package recommended.
Rev. 11/29/99
2-83
IRU1175
Notes
2-84
Rev. 11/29/99

7.5A ULTRA DROPOUT POSITIVE ADJUSTABLE REGULATOR 0.5V Dropout 7.5

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