SPX1583

SPX1583 1.5A Ultra Low Dropout Voltage Regulator Fast Response, Adjustable & Fixed FEATURES • Low Dropout Voltage 500mV at 1.5A Full Load Current • Adjustable Output Down to 1.2V from ATX Power Supply • Fixed Output Voltages of 3.3V, 2.8V, 2.5V, and 1.5V • Extremely Tight Voltage and Line Regulation • Standard 5-Terminal Low Cost TO-220 & TO-263 APPLICATIONS • 3.3V to 2.8V ATX Power Supplies • 3.3V to 2.9V for Portable PENTIUM Processor • 5V to 3.5V VRE Supply • High Efficiency “Green” Computer Systems PRODUCT DESCRIPTION The SPX1583 is a 1.5A Low Dropout Regulator with extremely low dropout voltage. The adjustable version requires only two external resistors to set the output voltage. The fixed version has a preset output of 3.3V, 2.8V or 2.5V and does not require any external resistors. The SPX1583 features a low dropout of less than 400mV(typ.) and offers fast transient response. This device is suitable for Pentium applications requiring 2.8V or 2.5V from 3.3V ATX power supplies, where a low current input voltage 1V greater than the output voltage is needed. With an external sense pin the load regulation is less than 1mV. This device is an excellent choice for the use in powering low voltage microprocessors that require a lower dropout, fast transient response to regulate from 3.3V and 5V supplies. The SPX1583 is also an excellent choice as a post regulator for switching supplies applications. The SPX1583 offers full protection against over-current faults, reversed input polarity, over temperature operation and positive and negative transient voltage. The SPX1583 is offered in a 5 pin TO-220 and TO-263 compatible with industry standard 5-terminal regulators. For 7A, 5A and 3A ultra low dropout versions refer to SPX1580, SPX1581 and SPX1582 data sheets respectively. PIN CONNECTIONS TO-263-5 (T) TO-220-5 (U) SPX1583 12345 1. 2. 3. 4. 5. SENSE ADJ or FIXED VOUT VCTRL VIN SPX1583 1 2 3 45 1. SENSE 2. ADJ or FIXED 3. VOUT 4. VCTRL 5. VIN Top View Front View Date: 5/14/04 SPX1583 ABSOLUTE MAXIMUM RATINGS Power Dissipation.................................................... Internally Limited Lead Temp (soldering, 10 seconds)........................................... 300°C Storage Temperature Range ...................................... -65ºC to +150ºC Operating Junction Temperature Range SPX1583 Control Section .............................................0ºC to +125ºC SPX1583 Power Transistor ...........................................0ºC to +150ºC Input Supply Voltage ..........................................................6V VCTRL Input Voltage ..........................................................13V ELECTRICAL CHARACTERISTICS at VS =14V, TA=25°C, Io=10mA, C2=100µF, unless otherwise specified. (Note 1) (Boldface applies over full temperature range). Parameters 2.5V Version Conditions Min SPX1583 Typ 2.500 Units Max 2.550 2.600 2.856 2.912 3.366 3.432 1.263 V Output Voltage 2.8V Version VCTRL=6.0V to 12V, VIN=3.0V to 5.0V, IO=10mA IO=10mA to 1.5A VCTRL=6.3V to 12V, VIN=3.3V to 12V, IO=10mA IO=10mA to 1.5A VCTRL=6.3V to 12V, VIN=3.3V to 12V, IO=10mA IO=10mA to 1.5A VCTRL=2.75V, VIN=2.00V, IO=10mA VCTRL=2.7V to 12V, VIN=2.05V to 5.5V, IO=10mA to 1.5A VCTRL=2.5V to 12V, VIN=1.75V to 5.5V, IO=10mA VADJ=0V VCTRL=2.75V, VIN=2.1V, IO=10mA to 1.5A,VADJ=0V VADJ=0V VIN=2.05V, IO=1A VADJ=0V VIN=2.75V, IO=1.5A VCTRL=2.75V, VIN=2.05V,dVO=100mV,VADJ=0V VCTRL=5V, VIN=3.3V,VADJ=0V 2.450 2.400 2.744 2.688 3.234 3.168 1.237 Output Voltage 3.3V Version 2.800 V Output Voltage All Voltage Options 3.300 V Reference Voltage Line Regulation Load Regulation (Note1) Dropout Voltage Minimum VCTRL (Note2) (VCTRL – VOUT) Dropout Voltage Minimum VIN(Note2) (VIN - VOUT) Current Limit Minimum Load Current Thermal Regulation Ripple Rejection Control Pin Current Adjustable Pin Current Thermal Resistance 1.250 V 1.0 1.0 1.00 3.0 5.0 1.15 mV mV V 0.40 0.50 V 1.6 5 0.002 60 80 60 50 120 90 3 50 3 60 10 0.02 A mA %W dB 30ms Pulse VCTRL=3.75V VIN=3.75V, IO=2.1.5A,VADJ=0V TJ=25, VRIPPLE=1Vpp at 120Hz VADJ=0V VCTRL =2.75V, VIN=2.05V, IO=1.5A VCTRL=2.75V, VIN=2.05V,VADJ=0V IO=10mA TO-220-5 Junction to Case (θJC) Junction to Ambient (θJA) TO-263-5 Junction to Case (θJC) Junction to Ambient (θJA) mA µA °C/W °C/W °C/W °C/W The Bold specifications applying to the over full operating temperature range. Note 1: Low duty cycle pulse testing with Kelvin connections is required to order to maintain accurate data. Note 2: Dropout voltage is defined as the minimum differential between VIN and VOUT or VCTRL and VOUT required to maintain regulation at VOUT 99% Nominal VOUT. Note 3: VREF is measured across Adjust pin to Sense pin. Date: 5/14/04 SPX1583 PIN DESCRIPTION 1. 2. 3. 4. 5. Sense = Allows Kelvin sense of VOUT at the load. (Positive side of the reference voltage of the device). ADJ = Negative side of the reference voltage for the device. Adding a small bypass capacitor from the ADJ pin to ground will improve the transient response. VOUT = Power output of the device. VCTRL = Supply pin for the control circuitry of the device. The current flow into this pin will be about 1% of the output current. VCTRL must be between 1.0V and 1.3V greater than the output voltage for the device to regulate. VIN = Output load current is supplied through this pin. VIN must be between 0.1V and 0.8V greater than the output voltage for the device to regulate. BLOCK DIAGRAM (4) VCTRL S.O.A VIN (5) CURRENT LIMIT AMPLIFIER LIMIT SENSE VOUT (3) THERMAL OVERLOAD SENSE (1) VOLTAGE REGULATION AMPLIFIER VREF ADJ (2) APPLICATIONS NOTES The SPX1583 is designed as a high performance and low cost solution for application requiring a lower dropout than traditional NPN regulators. The SPX1583 uses a separate input voltage VCTRL (VCTRL ≥ VOUT+ 1.3V) to minimize the dropout voltage. This allows the 2.5V power for the load to come from a 3.3V system supply. As added benefit this will reduce the heat dissipation, and lower heatsink and cooling fan cost. A typical application would use 5V for Vin and 3.3V for VCTRL from a motherboard power supply to provide a nominal 2.5V output. Using the sense pin allows to Kelvin measure the output, reducing resistive-associated errors. The SPX1583 can power the 2.5V core voltage for microprocessors such as Pentium, P55C, AMD5k86 and K6 and the IBM PowerPC 603EV and 604EV processors. 1.25V reference voltage is being developed between the SENSE pin and the ADJ pin of the SPX1583. Adding two external resistors (see fig 1.) will allow setting the output voltage from 1.25V to 6V. R1 is chosen so that this current is specified minimum load current of 10mA. R2 is given by the formula: VOUT = VREF (1+ R2/R1) + IADJ (R2). The current flowing from the ADJ pin is typically 50µA. This ADJ pin contributes to the final VOUT but is usually neglected. Connecting the sense pin to the top of the resistor divider will improve load regulation. Lowering Noise Using the SENSE pin to Kelvin the load will increase accuracy of the output voltage during load regulation. For the fixed voltage devices, adding a capacitor at the GND pin will improve transient response. This capacitor is chosen in the range of 1µF to 0.1µF and will depend on the amount of output capacitance in the system. *The reduction of heat dissipation is a result of the increase of the regulator efficiency (efficiency = VOUT / VIN). Adjustable Regulator Design Date: 5/14/04 SPX1583 TYPICAL APPLICATION Fig. 1 Adjustable Regulator 3.3V VIN 5V VCTRL C1 330uF VIN VOUT SPX1583 VCTRL ADJ C2 10uF 2.5V VOUT SENSE R1 124 Ω C4 2 X 330uF C3 .033uF R2 124 Ω (1) V CTRL needed when VIN < 5V. (2) V OUT = V REF (1 + R2/ R1) + I ADJ R2. (3) V REF is measured across adjust to sense. Fig.2 Typical Fixed Regulator 3.3V VIN C1 5V VCTRL 330uF VIN VOUT SPX1583 2.5V VOUT VCTRL GND C2 10uF SENSE C4 2 X 330uF (1) VCTRL is needed when VIN