L1581 ETC | Alldatasheet
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Dual Input Ultra Low Dropout Voltage Regulator (ULDO) L1581 Series TO-252 OCT-11-Y02 NIKO-SEM GENERAL DESCRIPTION The L1581 is a positive and very low dropout voltage regulat or 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 char acteristics 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 protec tion of the output device. The L1581 is a five terminal adjustable voltage regulator available in the popular 5 pin TO-252 packages.
FEATURES
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) Vin 0.033uF Vout Iadj Vo = Vref (1+R2/R1) + Iadj x R2 330uF L1581X OUTVin CTR'L ADJSENSE 10uF 330uF Vctrl Vref
Dual Input Ultra Low Dropout Voltage Regulator (ULDO) L1581 Series TO-252 OCT-11-Y02 NIKO-SEM Fixed Output Parts 330uF Vctrl L1581X-2.5 OUTVin CTR'L ADJSENSE 2.5V Vout 330uF 10uF Vin 330uF Vctrl L1581X-3.3 OUTVin CTR'L ADJSENSE 10uF 330uF Vin 3.3V Vout NOTES : (1) If the same voltage is input to both INPUT and CO NTROL, 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.
Dual Input Ultra Low Dropout Voltage Regulator (ULDO) L1581 Series TO-252 OCT-11-Y02 NIKO-SEM ABSOLUTE MAXIMUM RATINGS z Input Supply Voltage, VIN Control Input Voltage, VCTRL 13.2V z Operating Junction Temperature Range, T J 0 to 125 °C z Power Dissipation, PD Internally Limited z Storage Temperature Range, T STG -40 to 150 °C z Thermal Resistance Junction to Case, θJC 3 °C/W z Lead Temperature, TLEAD (Soldering, 10 Seconds) 260 °C z Thermal Resistance Junction to Ambient, θJA 60 °C/W ELECTRICAL CHARACTERISTICS (Unless otherwise specified, Vout = Vsns , Vadj = 0V , Cctl = Cin= Cout =10 uF,TJ = 25 °C) Parameter Symbol Test Conditions Typical Limits VCTRL=4.5V, VIN=2.05V, IOUT=10mA 1.237V~1.263V Reference Voltage(1) (Adj. Voltage Versions) VREF VCTRL = 4.5V, 10mA < IOUT < 5A, VIN = 2.05V 1.25V 1.231V~1.269V Dropout Voltage(1) (2) Minimum VIN VI - VO VCTRL = 4.75V, IOUT = 5A 0.54V 0.62V (Max) VCTRL = 5V, VIN = VOUT ＋ 0.8V, IOUT=10mA ± 1% Output Voltage(1) (Fixed Voltage Versions) V OUT VCTRL = 5V, 10mA < IOUT < 5A, VIN = VOUT ＋ 0.8V VOUT ± 1.5% Line Regulation(1) REG(LINE) VCTRL = 4.5V to 12V, VIN = (VOUT＋ 0.8V) to 5.5V, IOUT = 10mA 1.0mV 3.0mV Load Regulation REG (LOAD) VCTRL = 4.5V, VIN = (VOUT＋0.8V) , IOUT = 10mA ~ 5A 1.0mV 5.0mV Thermal Regulation(6) REG(Thermal) 0.002 % / W 0.02% / W Minimum Load Current(4) IO VCTRL = 5V, VIN = VOUT＋0.8V 5mA 10mA Adjust Pin Current I ADJ VCTRL = 4.5V, VIN = VOUT＋0.8V, IOUT = 10mA 50µA 120 µA Control Pin Current(3) ICTRL VCTRL = 4.5V, VIN = VOUT＋0.8V, IOUT = 5A 33mA 120mA Current Limit I CL VCTRL = 4.5V, VIN = VOUT＋0.8V ΔVOUT = 100mV 5.1A (Min)
Dual Input Ultra Low Dropout Voltage Regulator (ULDO) L1581 Series TO-252 OCT-11-Y02 NIKO-SEM Ripple Rejection Ratio(5) RA VCTRL = VIN = 5V, IOUT = 5A 80dB 60dB (Min) NOTE : (1) Low duty cycle pulse testing with Kelvin connections required. (2) Minimum input to output voltage differential required to maintain 1% regulation. (3) Current used to drive the output section. (4) Required to maintain regulation. Resistor divider R1, R2 is usually utilized for minimum load current. (5) V RIPPLE = 1VPK-PK, 120Hz. (6) 30ms. DEVICE SELECTION GUIDE Device L1581D L1581D-2.5 L1581D-3.3 Package TO-252 TO-252 TO-252 Marking L1581D L1581D-2.5 L1581D-3.3 PIN CONFIGURATIONS 21 543 Pin # Function
1 Sense
2 Adjust
3 Output
4 Control
5 Input
Note: TAB is Output Pin
Dual Input Ultra Low Dropout Voltage Regulator (ULDO) L1581 Series TO-252 OCT-11-Y02 NIKO-SEM PIN FUNCTIONS NO FUNCTION DESCRIPTION 1 Sense 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. Adjust 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.
3 Output 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).
Dual Input Ultra Low Dropout Voltage Regulator (ULDO) L1581 Series TO-252 OCT-11-Y02 NIKO-SEM TO-252 (DPAK) MECHANICAL DATA mm mm A 9.7 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 1.27BSC G 3.04 5.33 N