LT1573 Low Dropout PNP Regulator Driver FEATURES DESCRIPTIO Low Cost Solution for High Current, Low Dropout The LT 1573 is a regulator driver IC designed to provide Regulators a low cost solution for applications requiring high current, Fast Transient Response Needs Much Less low dropout and fast transient response. When combined Bulk Capacitance with an external PNP power transistor, this device pro- Latching Overload Protection Minimizes vides load current up to 5A with dropout voltages as low Heat Sink Size as 0.35V. The LT1573 circuitry is designed for extremely Precision Output Voltage (1%) fast transient response. This greatly reduces bulk storage Single Supply Operation: V = 2.8V to 10V capacitance when the regulator is used in applications IN Small Surface Mount Package with fast, high current load transients. Capable of Very Low Dropout Voltage (<0.2V) To keep cost and complexity low, the LT1573 uses a new Fixed or Adjustable Outputs time-delayed latching overcurrent protection technique Shutdown that requires no external current sense resistor. Base drive U is limited for instantaneous protection, and a time-delayed APPLICATIO S latch protects the regulator from continuous short circuits. 3.3V to 2.5V Regulators Microprocessor Power Sources The LT1573 is available as an adjustable regulator with an Post Regulator for Switching Supplies output range of 1.27V to 6.8V and with fixed output High Efficiency Linear Regulators voltages of 2.5V, 2.8V and 3.3V. Output accuracy is better Ultralow Dropout Regulators than 1% to meet the critical regulation requirement of fast Low Voltage Linear Regulators microprocessors. A special 8-pin, fused-lead surface mount package is used to minimize regulator footprint and pro- , LTC and LT are registered trademarks of Linear Technology Corporation. vide adequate heat sinking. TYPICAL APPLICATIO C C R 100pF C Transient Response for 1k 0.2A to 5A Output Load Step FB COMP LATCH V OUT LT1573 + C SHDN V TIME IN R D R B 50mV/DIV 24 Q 50 OUT GND DRIVE MOTOROLA D45H11 V V IN OUT 3.3V 5V R1 C OUT1 1.6k C + + C IN OUT2 1F 2.5A/DIV 100F 220F LOAD CER TANT TANT R2 24 1k 10s/DIV 1573 F01a GND V = 1.265V (1 + R1/R2) OUT 1573 F01 FOR T < 45C, C = 24 1F Y5V CERAMIC SURFACE MOUNT CAPACITORS. OUT1 FOR T > 45C, C = 24 1F X7R CERAMIC SURFACE MOUNT CAPACITORS. OUT1 PLACE C IN THE MICROPROCESSOR SOCKET CAVITY OUT1 Figure 1. 3.3V, 5A Microprocessor Supply sn1573 1573fas 1 U ULT1573 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) Input Pin Voltage (V to GND) ............................... 10V ORDER PART IN NUMBER Drive Pin Voltage (V to GND).......................... 10V DRIVE TOP VIEW Output Pin Voltage (V to GND) .......................... 10V OUT LT1573CS8 FB 1 8 COMP Shutdown Pin Voltage (V to GND) .................. 10V SHDN LT1573CS8-2.5 LATCH 2 7 V OUT Operating Junction Temperature Range LT1573CS8-2.8 SHDN 3 6 V IN LT1573C ............................................... 0C to 125C LT1573CS8-3.3 GND DRIVE 4 5 LT1573I ............................................ 40C to 125C LT1573IS8 Storage Temperature Range ................ 65C to 150C S8 PACKAGE 8-LEAD PLASTIC SO S8 PART MARKING Lead Temperature (Soldering, 10 sec.)................ 300C T = 125C, = 85C/ W JMAX JA 157333 1573 157325 1573I 157328 Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS The denotes specifications that apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 5V, V = 3V, unless otherwise noted. A IN DRIVE PARAMETER CONDITIONS MIN TYP MAX UNITS DC Characteristics LT1573 Reference Voltage (Adjustable)(Note 2) I = 20mA, T = 25C 1.252 1.265 1.278 V DRIVE J 5mA < I < 250mA, 3V < V < 7V, 1.225 1.265 1.305 V DRIVE IN 1.5V < V < 7V DRIVE LT1573-3.3 Output Voltage (Note 2) I = 20mA. T = 25C 3.267 3.3 3.333 V DRIVE J 5mA < I < 250mA, 3.5V < V < 7V, 3.234 3.3 3.366 V DRIVE IN 1.5V < V < 7V DRIVE LT1573-2.8 Output Voltage (Note 2) I = 20mA, T = 25C 2.772 2.8 2.828 V DRIVE J 5mA < I < 250mA, 3V < V < 7V, 2.744 2.8 2.856 V DRIVE IN 1.5V < V < 7V DRIVE LT1573-2.5 Output Voltage (Note 2) I = 20mA, T = 25C 2.475 2.5 2.525 V DRIVE J 5mA < I < 250mA, 3V < V < 7V, 2.450 2.5 2.550 V DRIVE IN 1.5V < V < 7V DRIVE Line Regulation LT1573 (V)I = 20mA, 3V < V < 7V 0.17 2 mV FB DRIVE IN LT1573-3.3 (V)I = 20mA, 3.5V < V < 7V 0.34 5 mV OUT DRIVE IN LT1573-2.8 (V)I = 20mA, 3V < V < 7V 0.34 4 mV OUT DRIVE IN LT1573-2.5 (V)I = 20mA, 3V < V < 7V 0.25 4 mV OUT DRIVE IN Load Regulation LT1573 (V ) I = 20mA to 250mA 730 mV FB DRIVE LT1573-3.3 (V ) I = 20mA to 250mA 18 40 mV OUT DRIVE LT1573-2.8 (V ) I = 20mA to 250mA 15 34 mV OUT DRIVE LT1573-2.5 (V ) I = 20mA to 250mA 13 30 mV OUT DRIVE FB Pin Bias Current (Adjustable Only) V = 1.265V 0.8 5 A FB DRIVE Pin Current V = 1.35V, V = 7V 2mA FB DRIVE V = 1.15V, V = 1.5V 250 440 mA FB DRIVE DRIVE Pin Saturation Voltage I = 20mA, V = 1.15V 0.12 0.3 V DRIVE FB I = 250mA, V = 1.15V 0.73 1.4 V DRIVE FB SHDN Pin Threshold Voltage 1.0 1.33 1.6 V SHDN Pin Current V = 5V 200 A SHDN sn1573 1573fas 2 U WWW