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| * DATA SHEET LND1117 800mA Low Dropout Voltage Regulator GENERAL DESCRIPTION The LND1117 series of positive adjustable and fixed regulators are designed to provide 800mA with higher efficiency than currently available devices. All internal circuitry is designed to operate down to 700 mV input to output differential and the dropout voltage is fully specified as a function of load current. Dropout voltage of the device is 100mV at light loads and rising to 700mV at maximum output current. A second low current input is required to achieve this dropout. The LND1117 can also be used as a single supply device( 3 pin version). On-chip trimming adjusts the reference voltage to 1%. FEATURES * * * * * * * * Adjustable or Fixed Output Output Current of 800mA Low Dropout 700mV at 800mA output current 0.015% Line Regulation 0.01% Load Regulation 100% Thermal limit Burn-In Fast Transient Response Remote Sense TYPICAL APPLICATION DATA 2.5 V, 800mA Regulator APPLICATIONS * * * High Efficiency Linear Regulators Post Regulators for Switching Supplies Adjustable Power Supply VOUT = VREF (1+R2/R1) +IADJ R2 * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND1117 PACKAGE INFORMATION 3 LEAD TO -220 (Front view) VIN VOUT ADJ/GND 5 LEAD TO -220 (Front View) Vpower Vcontrol OUTPUT ADJ/GND SENSE ABSOLUTE MAXIMUM RATING SYMBOL PD VIN PARAMETER Power Dissipation Input Voltage Vpower Vcontrol Operating Junction Temperature Range Control Section Power Transistor Storage Temperature Lead Temperature (Soldering,10 sec) MAXIMUM Internally Limited 7 13 UNITS W V TJ 0 to 125 0 to 150 -65 to 150 300 C TSTG TLEAD DEVICE SELECTION GUIDE (note 1) DEVICE LND1117 LND1117-1.5 LND1117-2.5 LND1117-2.85 LND1117-3.0 LND1117-3.3 LND1117-3.5 LND1117-5.0 Note 1: Other fixed versions are available Vout=1.5V to 5.0V OUTPUT VOLTAGE Adj. 1.5V 2.5V 2.85V 3.0V 3.3V 3.5V 5.0V * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND1117 ELECTRICAL CHARACTERISTICS Parameter Reference Voltage Device LND1117 LND1117-1.5 Test Conditions Vcontrol=2.75V, Vpower=2V,I load=10mA Vcontrol=2.7V to 12V Vpower=3.3V to 5.5V, Iload=10mA to 800mA Vcontrol=4V, Vpower=2V Vcontrol=3V,Vpower2.3, Iload= 0mA to 800mA Vcontrol=5V, Vpower=3.3V Vcontrol=4V, Vpower 3.3, I load= 0mA to 800mA Vcontrol=5.35V, Vpower=3.35V Vcontrol=4.4V, Vpower3.7, I load= 0mA to 800mA Vcontrol=5.5V, Vpower=3.5V Vcontrol=4.5V, Vpower3.8 I load= 0mA to 800mA Vcontrol=5.8V, Vpower=3.8V Vcontrol=4.8V, Vpower4.1, I load= 0mA to 800mA Vcontrol=6V, Vpower=4V Vcontrol=6.5V, Vpower5.8, I load= 0mA to 800mA Vcontrol=7.5V, Vpower=5.5V Vcontrol=6.5V, Vpower5.8, I load= 0mA to 800mA * Min 1.238 1.230 * 1.485 1.475 2.475 2.460 2.821 2.805 2.970 2.950 3.267 3.247 3.465 3.445 4.950 4.920 Typ 1.250 1.250 1.500 1.500 2.500 2.500 2.850 2.850 3.000 3.000 3.300 3.300 3.500 3.500 5.000 5.000 0.04 0.08 1.7 Max 1.262 Units V 1.270 1.515 1.525 2.525 2.540 2.879 2.895 3.030 3.050 3.333 3.353 3.535 3.555 5.050 5.080 0.20 0.40 5 V LND1117-2.5 * V LND11172.85 LND1117-3.0 Output Voltage LND1117-3.5 * V * V * V LND1117-5.0 * V * * * * V % % mA mA Line Regulation Load Regulation Minimum Load Current(Note 2) Control Pin Current (Note 3) Ground Pin Current Adjust Pin Current Current Limit Ripple Rejection All All LND1117 Iload=10mA(1.5V+Vout)<=Vcontrol <= 12V, 0.8V<=(Vpower-Vout)<=5.5V Vcontrol=Vout+2.5V, Vpower=Vout=0.8V I load =10mA to 800mA Vcontrol=5V,Vpower=3.3V Vadj=0V Vcontrol=Vout+2.5V, Vpower=Vout+0.8V,Iload=10mA to 800mA All LND11171.5/ -2.5/2.85/3.0/-3.3/-3.5/5.0 LND1117 All All * 10 20 Vcontrol=Vout+2.5V,Vpower=Vout +0.8V, Iload=10mA to 800mA * 6 10 mA Vcontrol=2.75V, Vpower==2.05V Iload=10mA (Vin-Vout)=3V Vcontrol= Vpower=Vout +2.5V,Vripple=1Vpp Iload=400mA * * * 800 60 50 1100 75 120 A mA dB * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND1117 Parameter Thermal Regulation Dropout Voltage Control Input (Vcontrol-Vout) Power Input (Vpower-Vout) Device LND1117 Test Conditions TA = 25C,30ms pulse Vpower=Vout+0.8V, Iload=10mA Vpower=Vout+0.8V, Iload=800mA Vcontrol= Vout+2.5V, Iload=800mA Min Typ 0.003 1.00 1.15 0.55 Max Units %/W All All * * 1.15 1.30 0.70 V V The *denotes the specifications which apply over the full temperature range. Note 1: Unless otherwise specified Vout=Vsense. For LND1117(adj) Vadj=OV Note 2: For the adjustable device the minimum load current is the minimum current required to maintain regulation. Normally the current in the resistor divider used to set the output voltage is selected to meet the minimum load current requirement. Note3: The control pin current is the drive current required for the output transistor. The current will track output current with a ratio of about 1:100. Note4: The dropout voltage for the LND1117 is caused by either minimum control voltage or minimum power voltage. The specifications represent the minimum input/output voltage required to maintain 1% regulation. PIN FUNCTIONS (5-LEAD) Sense (Pin 1): This pin is the positive side of the reference voltage. With this pin it is possible to Kelvin sense the output voltage at the load. Adjust (Pin 2): This pin is the negative side of the reference voltage. Adding a small bypass capacitor from the Adjust pin to ground improves the transient response. For fixed voltage devices the Adjust pin is also brought out to allow the user to add a bypass capacitor. GND (Pin 2): For fixed voltage devices this is the bottom of the resistor divider that sets the output voltage. Vpower (Pin 5): This pin is the collector of the power transistor. The output load current is supplied through this pin. The voltage at this pin must be 0.7V greater than the output voltage for the device to regulate. Vcontrol (pin 4): This pin is the supply pin for the control circuitry. The current flow into this pin will be about 1% of the output current. The voltage at this pin must be 1.3V greater than the output voltage for the device to regulate. Output (Pin 3): This is the power output of the device. BLOCK DIAGRAM * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND1117 APPLICATION INFORMATION The LND1117 is designed to make use of multiple power supplies, to reduce the dropout voltage. One of the advantages of the two supply approach is maximizing the efficiency. The second supply is at least 1V greater than output voltage and is providing the power for the NPN output transistor. This allows the NPN output transistor to be driven into saturation. For the control voltage the current requirement is small and equal to about 1% of the output current. This drive current becomes part of the output current. The maximum voltage on the control pin is 12V. The maximum voltage at the Power Pin is 7V. By trying the control and power inputs together the LND1117 can also be operated as a single supply device. In single supply operation the dropout will be determined by the minimum control voltage. Both the fixed and adjustable versions have remote sense pins, permitting very accurate regulation of output voltage. As a result, over an output current range of 100mA to 800mA, the typical load regulation is less than1mV. For the fixed voltages the adjust pin is brought out allowing the user to improve transient response by bypassing the internal resistor divider. Optimum transient response is provided using a capacitor in the range of 0.1F to Dimensions, Inc. 445 the Adjust pin. In Linear 1F for bypassing addition to the enhancements mentioned, the reference accuracy has been improved a factor or two with a guaranteed initial tolerance of 1% at 25C and 1.6% accuracy over the full temperature and load current range. Typical applications for the LND1117 include 3.3V to 2.5V conversion with a 5V control supply, 5V to 4.2V conversion with a 12V control supply. The device is fully protected against overcurrent and overtemperature conditions. Grounding and Output Sensing The LND1117 allows true Kelvin sensing for both the high and low side of the load. As a result the voltage regulation at the load can be easily optimized. Voltage drops due to parasitic resistance between the regulator and the load can be placed inside the regulation loop. The advantages of remote sensing are illustrated in figures 1 through 3. Figure 1 shows the device connected as a conventional 3 terminal regulator with the sense lead connected directly to the output of the device. RP is the parasitic resistanceof the connections between the device and the load.Trace A of figure 3, illiustrates the effect of RP. Figure 2, shows the device connected to take advantage of the remote sense feature. The sense pin and the top of the resistor divider are connected to the top of the load: the bottom of the load. The effect on output regulation can be seen in trace B of figure 3. It is important to note that the voltage drops due to Rp are not eliminated, they will add to the dropout voltage of the regulator regardless. The LND1117 can control the voltage at the load as long as the input-output voltage is greater than the total of the dropout voltage of the device plus the voltage drop across RP. Stability The circuit design used in the LND1117 series requires the use of an output capacitor as part of the device frequency compensation. The addition of 150F aluminum electrolytic or a 22F solid tantalum on the output will ensure stability for all operating conditions. * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND1117 Figure 1 Conventional Load Sensing 5.0V CONTROL 3.3V POWER SENSE Rp 3.3V Figure 2. Remote Load Sensing 5.0V CONTROL POWER SENSE Rp LND1117 OUTPUT ADJ LND1117 OUTPUT ADJ R1 R2 Rp LOAD R2 R1 LOAD Rp ( Vout Figure 1 Vout Figure 2 Iout ) (Rp) A B Iout Time Figure 3. Remote sensing improves Load Regulation * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND1117 Output Voltage The LND1117(adjustable version) develops a 1.25V reference voltage between the sense pin and the adjust pin ( figure 4). Placing a resistor between these two terminals causes a constant current to flow though 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, typically 50A and it adds to the current from R1. For best regulation the top of the resistor divider should be connected directly to the Sense pin. Figure 4. Setting Output Voltage Protection Diodes In normal operation LND1117 family does not need any protection diodes between the adjustment pin and the output and from the output to the input to prevent die overstress. 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. The adjust pin can be driver on a transient basis 7V with respect to the output without any device degradation. A protection diode between the Output pin and V power pin is not usually needed. Microsecond surge currents of pin is not usually needed. Microsecond surge currents of 50A to 100A can be handled by the internal diode between the output pin and Vpower pin of the device. In normal operations it is difficult to get those values of surge currents even with high value output capacitors, such as 1000F to 5000F and the Vpower pin is instantaneously shorted to ground, damage can occur. A diode from output to input is recommended(Figure 5) VOUT = VREF (1+R2/R1) +IADJ R2 Thermal Considerations The LND1117 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 junctionto-case, case-to-heat sink interface and heat sink resistance itself. Junction temperature of the Power section can run up to 150C. Figure 5. Optional Clamp Diodes Protect against Input Crowbar Circuits If LND1117 is connected as a single supply device with the control and power input pins shorted together the internal diode between the output and the power input pin will protect the control input pin. * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * |
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