LT1581/LT1581-2.5 10A, Very Low Dropout Regulators FEATURES DESCRIPTION n Low Dropout, 430mV at 10A Output Current The LT 1581 is a 10A low dropout regulator designed to n Fast Transient Response power the new generation of microprocessors. The drop- n Remote Sense out voltage of this device is 100mV at light loads rising to n 1mV Load Regulation just 430mV at 10A. To achieve this dropout a second low n Fixed 2.5V Output and Adjustable Output current input voltage 1V greater than the output voltage is n No Supply Sequencing Problems in required. The device can also be used as a single supply Dual Supply Mode device where dropout is comparable to an LT1584. Several other new features have been added to the LT1581. U A remote SENSE pin is brought out. This feature virtually APPLICATIONS eliminates output voltage variations due to load changes. n Microprocessor Supplies Typical load regulation for a load current step of 100mA to n Post Regulators for Switching Supplies 10A, measured at the SENSE pin, is less than 1mV. n High Current Regulators n The LT1581 has fast transient response, equal to the 5V to 3.XXV for Pentium Processors Operating LT1584. On fixed voltage devices, the ADJUST pin is at 90MHz to 166MHz and Beyond n brought out. A small capacitor on the ADJUST pin further 3.3V to 2.9V for Portable Pentium Processor TM n improves transient response. PowerPC Series Power Supplies This device is ideal for generating processor supplies of 2V to 3V on motherboards where both 5V and 3.3V supplies are available. , LTC and LT are registered trademarks of Linear Technology Corporation. Pentium is a registered trademark of Intel Corporation. PowerPC is a trademark of IBM Corporation. TYPICAL APPLICATION Dropout Voltage Minimum Power Voltage 2.5V Microprocessor Supply 0.8 INDICATES GUARANTEED TEST POINTS 2.5V/10A 0.7 3.3V POWER OUTPUT 10A + + 100F TANT 0.6 330F AVX TPS OS-CON 7 0.5 DATA SHEET LIMIT LT1581-2.5 0.4 5V CONTROL SENSE 0.2A 0.3 + GND ADJ T = 125C J 10F T = 25C J TANT 0.2 0.1F 1581 TA01 0.1 0 0 3 7 10 1 2 4 568 9 OUTPUT CURRENT (A) 1581 G03 1 MINIMUM POWER VOLTAGE (V) (V V ) (V) POWER OUT U ULT1581/LT1581-2.5 ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) V Input Voltage ................................................ 6V POWER ORDER PART FRONT VIEW V Input Voltage ........................................... 13V CONTROL NUMBER 7 NC Operating Junction Temperature Range 6 V CONTROL 5 V POWER Control Section...................................... 0C to 125C 4 OUTPUT LT1581CT7 3 SENSE Power Transistor ................................... 0C to 150C 2 NC/GND* LT1581CT7-2.5 ADJUST 1 Storage Temperature ............................ 65C to 150C TAB IS T7 PACKAGE Lead Temperature (Soldering, 10 sec).................. 300C OUTPUT 7-LEAD PLASTIC TO-220 = 50C/ W JA *PIN2 = NC FOR LT1581CT7, GND FOR LT1581CT7-2.5 PRECONDITIONING Consult factory for Industrial and Military grade parts. 100% Thermal Limit Functional Test ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. (Note 2) A PARAMETER CONDITIONS MIN TYP MAX UNITS Output Voltage: LT1581-2.5 V = 5V, V = 3.3V, I = 0mA 2.485 2.500 2.515 V CONTROL POWER LOAD V = 4V to 12V, V = 3V to 5.5V, I = 0mA to 4A l 2.475 2.500 2.525 V CONTROL POWER LOAD V = 4V to 12V, V = 3.3V to 5.5V, I = 0mA to 10A l 2.475 2.500 2.525 V CONTROL POWER LOAD Reference Voltage: LT1581 V = 2.75V, V = 2V, I = 10mA 1.243 1.250 1.257 V CONTROL POWER LOAD (V = 0V) V = 2.7V to 12V, V = 1.75V to 5.5V, I = 0mA to 4A l 1.237 1.250 1.263 V ADJ CONTROL POWER LOAD V = 2.7V to 12V, V = 2.05V to 5.5V, I = 0mA to 10A l 1.237 1.250 1.263 V CONTROL POWER LOAD Line Regulation: LT1581-2.5 V = 3.65V to 12V, V = 3V to 5.5V, I = 10mA l 13 mV CONTROL POWER LOAD LT1581 V = 2.5V to 12V, V = 1.75V to 5.5V, I = 10mA l 13 mV CONTROL POWER LOAD Load Regulation: LT1581-2.5 V = 5V, V = 3.3V, I = 0mA to 10A l 110 mV CONTROL POWER LOAD LT1581 (V = 0V) V = 2.75V, V = 2.1V, I = 10mA to 10A l 15 mV ADJ CONTROL POWER LOAD Minimum Load Current: LT1581 V = 5V, V = 3.3V, V = 0V (Note 4) l 310 mA CONTROL POWER ADJ Control Pin Current: LT1581-2.5 V = 5V, V = 3.3V, I = 100mA l 510 mA CONTROL POWER LOAD (Note 5) V = 5V, V = 3.3V, I = 4A l 20 50 mA CONTROL POWER LOAD V = 5V, V = 3.3V, I = 7A l 40 100 mA CONTROL POWER LOAD V = 5V, V = 3.3V, I = 10A l 70 170 mA CONTROL POWER LOAD Control Pin Current: LT1581 V = 2.75V, V = 2.05V, I = 100mA l 510 mA CONTROL POWER LOAD = 2.75V, V = 2.05V, I = 4A l 20 50 mA (Note 5) V CONTROL POWER LOAD V = 2.75V, V = 2.05V, I = 7A l 40 100 mA CONTROL POWER LOAD V = 2.75V, V = 2.05V, I = 10A l 70 170 mA CONTROL POWER LOAD Ground Pin Current: LT1581-2.5 V = 5V, V = 3.3V, I = 0mA l 610 mA CONTROL POWER LOAD Adjust Pin Current: LT1581 (V = 0V) V = 2.75V, V = 2.05V, I = 10mA l 60 120 A ADJ CONTROL POWER LOAD Current Limit: LT1581-2.5 V = 5V, V = 3.3V, V = 100mV l 10.1 11 A CONTROL POWER OUT LT1581 (V = 0V) V = 2.75V, V = 2.05V, V = 100mV l 10.1 11 A ADJ CONTROL POWER OUT Ripple Rejection: LT1581-2.5 V = V = 5V Avg, V = 1V , f = 120Hz, 55 80 dB CONTROL POWER RIPPLE P-P RIPPLE I = 4A, T = 25C OUT J LT1581 V = V = 3.75V Avg, V = 1V , f = 120Hz, 60 80 dB CONTROL POWER RIPPLE P-P RIPPLE V = 0V, I = 4A, T = 25C ADJ OUT J Thermal Regulation 30ms Pulse 0.004 0.020 %/W Thermal Resistance, Junction-to-Case Control Circuitry/Power Transistor 0.65/2.50 C/W 2 U U U U W U W U WW