LT1587-1.5 Fixed 1.5V, 3A Low Dropout Fast Response + GTL Regulator FEATURES DESCRIPTION n Fast Transient Response The LT 1587-1.5 is a low dropout 3-terminal regulator n Guaranteed Dropout Voltage at Multiple Currents with a fixed 1.5V output voltage and 3A output current n Load Regulation: 0.05% Typ capability. The design is optimized for low voltage applica- n Trimmed Current Limit tions where transient response and minimum input voltage n On-Chip Thermal Limiting are critical. Similar to the LT1085, it has lower dropout and faster transient response. These improvements make it U ideal for low voltage microprocessor applications, espe- APPLICATIONS cially as the regulator in an Intel Pentium Pro processor n + Intel Pentium Pro Processor GTL Supply + GTL supply. n Low Voltage Logic Supplies Current limit is trimmed to ensure specified output current n Battery-Powered Circuitry and controlled short-circuit current. On-chip thermal lim- iting provides protection against any combination of over- load that creates excessive junction temperatures. The LT1587-1.5 is available in both the through-hole and surface mount versions of the industry standard 3-pin TO-220 power package. , LTC and LT are registered trademarks of Linear Technology Corporation. Pentium is a registered trademark of Intel Corporation TYPICAL APPLICATION + Intel Pentium Pro Processor GTL Supply V = 1.5V V = 1.5V TT TT LT1587-1.5 LT1587-1.5 3A 3A 3.3V 3.3V V V V V IN OUT OUT IN C4 TO R6 R1 R5 R7 R8 R3 GND GND C6 100 75 100 100 100 75 1F C10 TO C12 V V + C7 REF REF C1 C2, C3 C8, C9 1F 100F + + 100F 100F 100F C13 C14 10V 10V R2 R4 10V 10V 0.1F 0.1F AVX TPS 150 150 AVX TPS AVX TPS AVX TPS RX RX TX Q1 TX Q2 RX RX NOTE: LTC RECOMMENDS SEPARATE V GENERATORS AT EACH BUS END TT TX Q3 Q4 TX TO ENSURE CURRENT SHARING BETWEEN THE REGULATORS AND TO MINIMIZE V DISTRIBUTION DROPS TT LT1587 TA01 142 TOTAL SIGNAL LINES 1 + U ULT1587-1.5 ABSOLUTE MAXIMUM RATINGS Storage Temperature Range ................. 65C to 150C V ............................................................................. 7V IN Lead Temperature (Soldering, 10 sec).................. 300C Operating Junction Temperature Range Control Section.................................... 0C to 125C PRECONDITIONI G Power Transistor ................................. 0C to 150 C 100% Thermal Limit Functional Test PACKAGE/ORDER INFORMATION FRONT VIEW FRONT VIEW ORDER PART ORDER PART NUMBER NUMBER 3 V 3 V IN IN 2 V 2 V OUT OUT LT1587CM-1.5 LT1587CT-1.5 1 GND 1 GND T PACKAGE M PACKAGE 3-LEAD PLASTIC TO-220 3-LEAD PLASTIC DD = 30C/W* = 50C/W JA JA * With package soldered to 0.5 square inch copper area over backside Consult factory for Industrial and Military grade parts. ground plane or internal power plane. can vary from 20C/W to JA >40C/W with other mounting techniques. ELECTRICAL CHARACTERISTICS PARAMETER CONDITIONS MIN TYP MAX UNITS Output Voltage V = 5V, T = 25C, I = 0mA 1.485 ( 1%) 1.5 1.515 (+1%) V IN J OUT 3V V 7V, 0mA I 3A l 1.470 ( 2%) 1.5 1.530 (+2%) V IN OUT Line Regulation (Notes 1, 2) 3V V 7V, I = 0mA 0.005 0.2 % IN OUT Load Regulation V = 5V, T = 25C, 0mA I I 0.05 0.3 % IN J OUT FULL LOAD (Notes 1, 2, 3) l 0.05 0.5 % Dropout Voltage V = 1%, I = 3A l 1.150 1.300 V OUT OUT Current Limit (Note 3) (V V ) = 5.5V l 3.100 3.750 A IN OUT Quiescent Current V = 5V l 713 mA IN Ripple Rejection f = 120Hz, C = 25F Tant., V = 4.5V, I = 3A l 60 72 dB OUT IN OUT Thermal Regulation T = 25C, 30ms pulse 0.004 0.02 %/W A Temperature Stability l 0.5 % Long-Term Stability T = 125C, 1000 Hrs. 0.03 1.0 % A RMS Output Noise T = 25C, 10Hz f 10kHz 0.003 % A (% of V ) OUT Thermal Resistance T Package: Control Circuitry/Power Transistor 0.7/3.0 C/W Junction to Case M Package: Control Circuitry/Power Transistor 0.7/3.0 C/W The l denotes specifications which apply over the specified operating dissipation is determined by input/output differential and the output temperature range. current. Guaranteed maximum output power will not be available over the full input/output voltage range. Note 1: See thermal regulation specifications for changes in output voltage due to heating effects. Load and line regulation are measured at a constant Note 3: I is defined as the maximum value of output load current FULL LOAD junction temperature by low duty cycle pulse testing. as a function of input-to-output voltage. I is equal to 3A. The FULL LOAD LT1587-1.5 has constant current limit with changes in input-to-output Note 2: Line and load regulation are guaranteed up to the maximum voltage. power dissipation (17W for the LT1587-1.5 in T package). Power 2 U W U U U U U WWW