LND1085

• DATA SHEET LND1086/85 1.5 A / 3 A Low Dropout Voltage Regulators GENERAL DESCRIPTION The LND1086/LND1085 Series 1.5/3.0A fixed and adjustable voltage regulators are monolithic integrated circuits designed to power the new generation of microprocessors for use in applications requiring a well regulated positive output voltage with low input-output differential voltage requirements and output voltage 3.3, 2.9V or 2.5V. Outstanding features include full power usage up to 1.5/3.0A of load current, internal current limiting and thermal shutdown. Other fixed versions are also available Vout=2.0V to 4.0V. Please consult Linear Dimensions for more information. FEATURES • • • • • • Fixed Output Voltage 3.3, 2.9V, 2.5V Low Dropout Performance, 1V at Full load Line Regulation Typically 0.015% Load Regulation Typically 0.1% Fast Transient Response TO-220 Packages DEVICE SELECTION GUIDE Device LND1086 LND1085 VOut(V) 3.3, 2.9, 2.5 3.3, 2.9,2.5 IOut(A) 1.5 3.0 APPLICATIONS • • • • • • FIXEDVOLTAGE REGULATOR Microprocessor Supplies Post Regulators for Switching Supplies High Current Regulators 5V to 3.XXV for Pentium Processors 3.3V to 2.5V for Portable Pentium Processor Power PC Series Power Supplies • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com • LND1085/86 PACKAGE INFORMATION T Package TO–220 Plastic Front View K PackageTO-3 Metal Can Bottom View P Package TO–3P Plastic Front View ABSOLUTE MAXIMUM RATING SYMBOL VIN Po θJC θJA TJ TSTG TLEAD PARAMETER Input Voltage Power Dissipation Thermal resistance Junction to Case Thermal Resistance Junction to Ambient Operating Junction Temperature Range Control Section Power Transistor Storage Temperature Lead Temperature(soldering,10 sec) MAXIMUM 6 Internally Limited 3 50 0 to 125 0 to 150 -65 to 150 260 UNITS V W ºC/W ºC BLOCK DIAGRAM • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com • LND1085/86 ELECTRICAL CHARACTERISTICS (VIN =4.75 V to 5.25 V; Io =10mA to 3.0A(LND1085) ; Io = 10mA to 1.5 A(LND1086), Unless otherwise specified) Test Conditions Parameter Output Voltage LND1086-3.3/LND1085-3.3 Symbol Vin Vo Vo LND1086-2.9/LND1085-2.9 Vo LND1086-2.5/LND1085-2.5 Line Regulation(1) Load regulation(1) REG(Line) REG(Load) 5V 10mA 5V 10mA 5V 5V Io 10mA 10mA Tj(3) 25 °C Over temp. 25 °C Over temp. 25 °C Over temp. 25 °C Over temp. 25 °C Over temp 25 °C Over temp. Min 3.267 3.234 2.871 2.842 2.475 2.450 0.015 0.035 0.1 0.2 1.0 1.1 Current surge Limit LND1085 LND1086 Quiescent current Temperature Coefficient Temperature Stability RMS Output Noise(2) Ripple Rejection ratio LND1085 LND1086 IS 4.5 2.5 10 0.005 0.5 0.003 60 72 0.3 0.4 V 1.3 A Typ 3.3 2.9 Max 3.333 3.366 2.929 2.958 2.525 2.550 0.2 V Test Limits Units 2.5 % Dropout Voltage ∆Vout=2% VD IQ TC TS VN RA 5V 5V 0.5A 25°C 5V 3.0A 1.5A Over temp. 16 mA %/ °C % %Vo dB (1) Low duty cycle pulse testing (2) Bandwidth of 10 Hz to 10kHz (3) Over temp.= over specified operating junction temperature range. • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com • LND1085/86 APPLICATIONS INFORMATION The LND1086 family of three-terminal adjustable regulators is easy to use and has all the protection features that are expected in high performance voltage regulators. Stability The circuit design used in the LND1086 series requires the use of an output capacitor as part of the device frequency compensation. The addition of 150 µF aluminum electrolytic or a 22 µF solid tantalum on the output will ensure stability for all operating conditions. Output Voltage The LND1086 develops a 1.25V reference voltage between the Output pin and the Adjust pin (Figure 1). Placing a resistor between these two terminals causes a constant current to flow through R1 and down though R2 to set the output voltage. In general R1 is chosen so that this current is the specified minimum load current of 10mA. The current out of the Adjust pin is small as compared to the current from R1 and can be ignored. For fixed voltage devices R1 and R2 are included in the device. Figure 1. Output Voltage Figure 2. Protection Diodes Microsecond surge currents of 10A to 20A can be handled by the internal diode between the Output pin and the Input pin of the device. In normal operations it is difficult to get those values of surge currents even with the use of large output capacitance. Only with high value output capacitors, such as 1000 to 5000µF and with the Input pin instantaneously shorted to ground, can damage occur. A diode from output to input is recommended (Figure 2). Protection Diodes In normal operation LND1086 family does not need any protection diodes between the adjustment pin and the output and from the output to the input to prevent die overstresses. Internal resistors are limiting the internal current paths on the ADJ pin. Therefore even with bypass capacitors on the adjust pin no protection diode is needed to ensure device safety under short-circuit conditions Thermal Considerations The LND1086 series have internal power and thermal-limiting circuitry designed to protect the device under overload conditions. However, maximum junction temperature ratings should not be exceeded under continuous normal load conditions. Careful consideration must be given to all sources of thermal resistance from junction to ambient, including junction-to-case, case to-heat sink interface and heat sink resistance itself. • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com • LND1085/86 TYPICAL APPLICATIONS Improving ripple rejection 1.2V to 15v adjustable regulator 5V regulator with shutdown Automatic light control • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •