LT1575/LT1577 Ultrafast Transient Response, Low Dropout Regulators Adjustable and Fixed DESCRIPTION FEATURES TM n UltraFast Transient Response Eliminates The LT 1575/LT1577 are single/dual controller ICs that Tantalum and Electrolytic Output Capacitors drive low cost external N-channel MOSFETs as source n FET R Defines Dropout Voltage followers to produce ultrafast transient response, low DS(ON) n 1% Reference/Output Voltage Tolerance Over dropout voltage regulators. Temperature The LT1575/LT1577 achieve unprecedented transient- n Typical Load Regulation: 1mV load performance by eliminating expensive tantalum or n High Side Sense Current Limit bulk electrolytic output capacitors in the most demanding n Multifunction Shutdown Pin with Latchoff modern microprocessor applications. Precision-trimmed U adjustable and fixed output voltage versions accommo- APPLICATIONS date any required microprocessor power supply voltage. n Pentium Processor Supplies Selection of the N-channel MOSFET R allows very DS(ON) TM n PowerPC Supplies low dropout voltages to be achieved. n 5V to 3.XXV or 3.3V to 2.XXV Microprocessor Supplies Unique protection features include a high side current n GTL Termination limit amplifier that activates a fault protection timer n Low Voltage Logic Supplies circuit. A multifunction Shutdown pin provides either LT1575CN8/LT1575CS8 Adjustable current limit time-out with latchoff, overvoltage protec- LT1575CN8-1.5/LT1575CS8-1.5 1.5V Fixed tion, thermal shutdown or a combination of these func- LT1575CN8-2.8/LT1575CS8-2.8 2.8V Fixed tions. The LT1575 is available in 8-pin SO or PDIP and the LT1575CN8-3.3/LT1575CS8-3.3 3.3V Fixed LT1577 is available in 16-pin narrow body SO. LT1575CN8-3.5/LT1575CS8-3.5 3.5V Fixed , LTC and LT are registered trademarks of Linear Technology Corporation. LT1575CN8-5/LT1575CS8-5 5V Fixed UltraFast is a trademark of Linear Technology Corporation. LT1577CS-ADJ/ADJ Adjustable, Adjustable Pentium is a registered trademark of Intel Corporation. PowerPC is a trademark of IBM Corporation. LT1577CS-3.3/ADJ 3.3V Fixed, Adjustable LT1577CS-3.3/2.8 3.3V Fixed, 2.8V Fixed Consult factory for additional output voltage combinations available in the LT1577. TYPICAL APPLICATION Transient Response for 0.2A to 5A Output Load Step Ultrafast Transient Response 5V to 3.3V Low Dropout Regulator (For Schematic Including Current Limit, See Typical Applications) LT1575-3.3 12V 1 8 SHDN IPOS 5V 50mV/DIV 2 7 + *FOR T < 45C: C5 C2 V INEG IN 220F C6 = 24 1F Y5V 1F 3 6 Q1 GND GATE CERAMIC SURFACE IRFZ24 R2 4 5 MOUNT CAPACITORS. OUT COMP 5 V FOR T > 45C: OUT 3.3V C6 = 24 1F X7R 5A 2A/DIV CERAMIC SURFACE R1 MOUNT CAPACITORS. C6* C3 7.5k PLACE C6 IN THE 24F 10pF C4 MICROPROCESSOR 1000pF SOCKET CAVITY GND 1575/77 TA02 100s/DIV 1575/77 TA01 1 U ULT1575/LT1577 ABSOLUTEXAI U RATI GS (Note 1) V , IPOS, INEG ...................................................... 22V Junction Temperature (Note 2)................ 0C to 100C IN SHDN....................................................................... V Storage Temperature Range ................ 65C to 150C IN Operating Ambient Temperature Range ..... 0C to 70C Lead Temperature (Soldering, 10 sec)................. 300C PACKAGE/ORDER I FOR ATIO TOP VIEW TOP VIEW SHDN 1 IPOS 8 SHDN 1 8 IPOS TOP VIEW V 2 7 INEG V INEG IN 2 7 IN GND 3 6 GATE GND 3 6 GATE SHDN1 1 16 IPOS1 FB 4 COMP 5 OUT 4 5 COMP V 2 15 INEG1 IN1 GND1 3 14 GATE1 N8 PACKAGE S8 PACKAGE N8 PACKAGE S8 PACKAGE 8-LEAD PDIP 8-LEAD PLASTIC SO 8-LEAD PDIP 8-LEAD PLASTIC SO FB1 4 13 COMP1 T = 100C, = 100C/ W (N8) T = 100C, = 100C/ W (N8) SHDN2 5 12 IPOS2 JMAX JA JMAX JA T = 100C, = 130C/ W (S8) T = 100C, = 130C/ W (S8) JMAX JA JMAX JA V 6 11 INEG2 IN2 GND2 7 10 GATE2 ORDER PART NUMBER ORDER PART NUMBER FB2 8 9 COMP2 LT1575CN8 LT1575CN8-1.5 LT1575CS8-3.3 S PACKAGE 16-LEAD PLASTIC NARROW SO LT1575CS8 LT1575CS8-1.5 LT1575CN8-3.5 T = 100C, = 100C/ W JMAX JA LT1575CN8-2.8 LT1575CS8-3.5 LT1575CS8-2.8 LT1575CN8-5 LT1575CN8-3.3 LT1575CS8-5 S8 PART MARKING S8 PART MARKING ORDER PART NUMBER 157535 LT1577CS-ADJ/ADJ 1575 157515 157528 15755 157533 TOP VIEW TOP VIEW SHDN1 1 16 IPOS1 SHDN1 1 16 IPOS1 V 2 15 INEG1 V 2 15 INEG1 IN1 IN1 GND1 3 14 GATE1 GND1 3 14 GATE1 OUT-3.3 4 13 COMP1 OUT-3.3 4 13 COMP1 SHDN2 5 12 IPOS2 SHDN2 5 12 IPOS2 V 6 11 INEG2 V 6 11 INEG2 IN2 IN2 GND2 7 10 10 GATE2 GND2 7 GATE2 FB 8 9 9 COMP2 OUT-2.8 8 COMP2 S PACKAGE S PACKAGE 16-LEAD PLASTIC NARROW SO 16-LEAD PLASTIC NARROW SO T = 100C, = 100C/ W T = 100C, = 100C/ W JMAX JA JMAX JA ORDER PART NUMBER ORDER PART NUMBER LT1577CS-3.3/ADJ LT1577CS-3.3/2.8 Consult factory for Industrial and Military grade parts. 2 U WU U W W W