Dual Input Ultra Low Dropout Voltage Regulator (ULDO) NIKO-SEM L1581 Series TO-252 GENERAL DESCRIPTION FEATURES The L1581 is a positive and very low dropout voltage regulator with 5A output current capability. When supplying 2.5V or 2.8V on Motherboards or VGA Card where both 5V and 3.3V supplies are available, the superior dropout characteristics of the L1581 result in reduced heat dissipation compared to regular LDOs, thus allowing heat sink reduction. The adjustable version requires only two external resistors to set the output. The L1581 features a low dropout of less than 600mV and offers fast transient response, remote sense, internal limiting, thermal shutdown and safe operating area protection of the output device. The L1581 is a five terminal adjustable voltage regulator available in the popular 5 pin TO-252 packages. z Low dropout voltage 600mV at rated load current z Remote sense operation z Fast transient response z 0.5% voltage reference initial accuracy z Standard 5 terminal, Low cost TO-252 packages APPLICATIONS z 3.3V to 2.8V or 2.5V for Motherboards or VGA Card z Spilt plane microprocessor supplies z Post regulator for switching supplies TYPICAL APPLICATION Adjustable Output Parts(2) L1581X 4 OUT CTR'L ADJ Vctrl Vin SENSE 3 Vout 1 2 Vin 5 Vref R1 C1 C2 330uF 10uF Iadj C4 330uF C3 0.033uF R2 Vo = Vref (1+R2/R1) + Iadj x R2 1 OCT-11-Y02 Dual Input Ultra Low Dropout Voltage Regulator (ULDO) NIKO-SEM L1581 Series TO-252 Fixed Output Parts L1581X-2.5 4 C1 C2 330uF 10uF OUT ADJ Vctrl Vin CTR'L SENSE 3 2.5V Vout 1 C4 2 Vin 5 330uF L1581X-3.3 Vctrl 4 C1 C2 330uF 10uF Vin OUT CTR'L ADJ 5 2 Vin SENSE 3 3.3V Vout 1 C4 330uF NOTES : (1) If the same voltage is input to both INPUT and CONTROL, then the dropout voltage will become 1.3V maximum. (2) A small (~0.033uF) capacitor can be used to bypass the ADJUST pin to improve transient response, if needed. (3) Capacitor values are for reference only. Good quality, low ESR tantalum or aluminum electrolytic capacitors should be used. Increasing the value of the output capacitor will improve the overall transient response. 2 OCT-11-Y02 Dual Input Ultra Low Dropout Voltage Regulator (ULDO) NIKO-SEM L1581 Series TO-252 ABSOLUTE MAXIMUM RATINGS z Input Supply Voltage, VIN Control Input Voltage, VCTRL 7V 13.2V Internally Limited z Power Dissipation, PD z Thermal Resistance Junction to Case, θJC z Thermal Resistance Junction to Ambient, θJA z Operating Junction Temperature Range, TJ z Storage Temperature Range, TSTG z Lead Temperature, TLEAD (Soldering, 10 Seconds) 3 °C/W 0 to 125 °C -40 to 150 °C 260 °C 60 °C/W ELECTRICAL CHARACTERISTICS (Unless otherwise specified, Vout = Vsns , Vadj = 0V , Cctl = Cin= Cout =10 uF,TJ = 25 °C) Parameter Reference Voltage(1) (Adj. Voltage Versions) Dropout Voltage(1) (2) Minimum VIN Output Voltage(1) (Fixed Voltage Versions) Line Regulation(1) Load Regulation Symbol Test Conditions Typical VCTRL=4.5V, VIN=2.05V, IOUT=10mA VREF VCTRL = 4.5V, 10mA < IOUT < 5A, VIN = 2.05V VI - VO VCTRL = 4.75V, IOUT = 5A VOUT VCTRL = 5V, VIN = VOUT ＋ 0.8V, IOUT=10mA VCTRL = 5V, 10mA < IOUT < 5A, VIN = VOUT ＋ 0.8V REG(LINE) VCTRL = 4.5V to 12V, VIN = (VOUT＋ 0.8V) to 5.5V, IOUT = 10mA REG(LOAD) VCTRL = 4.5V, VIN = (VOUT＋0.8V) , IOUT = 10mA ~ 5A Thermal Regulation(6) REG(Thermal) Limits 1.237V~1.263V 1.25V 0.54V 1.231V~1.269V 0.62V (Max) ± 1% VOUT ± 1.5% 1.0mV 3.0mV 1.0mV 5.0mV 0.002 0.02% / W %/W Minimum Load (4) Current IO VCTRL = 5V, VIN = VOUT＋0.8V 5mA 10mA Adjust Pin Current IADJ 50µA 120µA Control Pin Current(3) ICTRL VCTRL = 4.5V, VIN = VOUT＋0.8V, IOUT = 10mA VCTRL = 4.5V, VIN = VOUT＋0.8V, IOUT = 5A VCTRL = 4.5V, VIN = VOUT＋0.8V ΔVOUT = 100mV 33mA 120mA Current Limit ICL 3 5.1A (Min) OCT-11-Y02 NIKO-SEM Dual Input Ultra Low Dropout Voltage Regulator (ULDO) Ripple Rejection Ratio(5) RA VCTRL = VIN = 5V, IOUT = 5A L1581 Series TO-252 80dB 60dB (Min) NOTE : (1) (2) (3) (4) (5) Low duty cycle pulse testing with Kelvin connections required. Minimum input to output voltage differential required to maintain 1% regulation. Current used to drive the output section. Required to maintain regulation. Resistor divider R1, R2 is usually utilized for minimum load current. VRIPPLE = 1VPK-PK, 120Hz. (6) 30ms. DEVICE SELECTION GUIDE Device L1581D Package TO-252 Marking L1581D L1581D-2.5 L1581D-3.3 TO-252 TO-252 L1581D-2.5 L1581D-3.3 PIN CONFIGURATIONS 1 2 3 4 5 Pin # Function 1 Sense 2 Adjust 3 Output 4 Control 5 Input Note: TAB is Output Pin 4 OCT-11-Y02 NIKO-SEM Dual Input Ultra Low Dropout Voltage Regulator (ULDO) L1581 Series TO-252 PIN FUNCTIONS NO FUNCTION 1 Sense 2 Adjust 3 Output 4 Control 5 Input DESCRIPTION This pin is the positive side of the reference voltage for the device. With this pin it is possible to Kelvin sense the output voltage at the load. This pin is the negative side of the reference voltage for the device. Transient response can be improved by adding a small bypass capacitor from the adjust pin to ground. This is the power output of the device, and is electrically connected to the TAB. This pin is the supply pin for the control circuitry for the device. The current flow into this pin will be approximately 1% of the output. For the device to regulate, the voltage at this pin must be between 1.0V and 1.3V greater than the output voltage (see dropout specifications). This is the collector input to the power device of the L1581. The output load current is supplied through this pin. For the device to regulate, the voltage on this pin must be between 0.1V and 0.7V greater than the output, depending upon load current (see dropout specifications). 5 OCT-11-Y02 NIKO-SEM Dual Input Ultra Low Dropout Voltage Regulator (ULDO) L1581 Series TO-252 TO-252 (DPAK) MECHANICAL DATA Dimension mm Min. A Typ. Max. Dimension 9.7 mm Min. Typ. Max. H 0.89 2.03 B 2.19 2.38 I 6.35 6.73 C 0.46 0.58 J 5.21 5.46 D 0.89 1.27 K E 0.46 0.53 L 0.64 0.89 F 0.00 0.13 M G 3.04 5.33 N 1 2 3 4 5 1.27BSC 6 OCT-11-Y02