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5A Low-Voltage Low-Dropout Regulator
LM39500/39501/39502
TO263-3L / TO220-3L
(39500-x.x Fixed only)
FEATURES
*5.0A minimum guaranteed output current *400mV typical dropout voltage Ideal for 3.0V to 2.5V conversion Ideal for 2.5V to 1.8V or 1.5V conversion *1% initial accuracy
1. In 2. Gnd 3. Out
*Low ground current
*Current limiting and thermal shutdown
TO263-5L / TL220-5L
(39501-x.x & 39502 only)
*Reversed-battery protection
*Reversed-leakage protection *Fast transient response *TTL/CMOS compatible enable pin-LM39501 only *Error flag output - LM39501 only *Ceramic capacitor stable(See application information) *Adjustable version - LM39502 only
1. 2. 3. 4. 5.
En In Gnd Out Flg or Adj
APPLICATIONS
*Low-voltage Digatal Ics *LDO linear regulator for PC add-in cards *High-efficiency linear power supplies *Multimedia and PC processor supplies *SMPS post regulator *Low-voltage microcontrollers *Strong ARMTM processor supply
PIN DESCRIPTION CMOS-compatible control input. Enable (Input) IN GND OUT FLG ADJ Logic high = enable, logic Logic low or open = Shutdown Supply (Input): +16V maximum supply Ground pin and TAB are internally connected. Regulator Output Flag (Output): Open-collector error flag output. Adjustment Input: Feedback input.
ORDERING INFORMATION
Device LM39500R- X.X LM39500T-X.X LM39501R-X.X LM39501T-X.X LM39502R-Adj LM39502T-Adj Marking LM39500-X.X LM39500-X.X LM39501-X.X LM39501-X.X LM39502-Adj LM39502-Adj Package TO-263 TO-220 TO-263 TO-220 TO-263 TO-220
DESCRIPTION
The LM39500, LM39501 and LM39502 is a 5A low-dropout linear voltage regulator that provides a low-voltage, high-current output with a minimum of external components. Utilizing Super * X.X = Fixed Vout = 1.5V, 1.8V, 2.5V, 3.3V, 5.0V beta PNP pass element, The LM39500 offers extremely low dropout (typically 400mV at 5A) and low ground current (typically 70mA at 5A). The LM39500/1/2 is ideal for PC Add-In cards that need to convert from standard 5V or 3.3V, down to new, lower core voltages. A guaranteed maximum dropout voltage of 500mV over all operating conditions allows the LM39500/1/2 to provide 2.5V from a supply as low as 3V. The LM39500 also has fast transient response, for heavy switching applications. The device requires only 47F of output capacitance to maintain stability and achieve fast transient responseThe LM39500/1/2 is fully protected with overcurrent limiting,thermal shutdown, reversed-battery and reversed-lead in-sertion protection. The LM39501 offers a TTL-logic-compat-ible enable pin and an error flag that indicates undervoltage and overcurrent conditions. The LM39500/1/2 comes in the TO-220 and TO-263 packages and is an ideal upgrade to older,NPN-based linear voltage regulators. The LM39502 is adjustable version.
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5A Low-Voltage Low-Dropout Regulator
LM39500/39501/39502
Typical Application Circuit
LM39500
LM39501
LM39502
Absolute Maximum Ratings (Note 1) Supply Voltage (VIN) : -20V to +20V Enable Voltage (VEN) : +20V Storage Temperature (TS) : -65C to +150C Lead Temperature (soldering, 5 sec) : 260C ESD, Note 3 Operating Ratings (Note 2) Supply Voltage (VIN) : +2.25V to +16V Enable Voltage (VEN) : +16V Maximum Power Dissipation (PD(max)) Note 4 Junction Temperature (TJ) : -40C to +125C Package Thermal Resistance TO-263(JC) : 2C/W TO-220(JC) : 2C/W
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5A Low-Voltage Low-Dropout Regulator
Block Diagram
LM39500/39501/39502
LM39500 Fixed (1.5V,1.8V,2.5V,3.3V,5.0V)
LM39501 Fixed with Flag and Enable
LM39502 Adjustable
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5A Low-Voltage Low-Dropout Regulator
LM39500/39501/39502
Note Note Note Note Note Note Note Note Note
1. Exceeding the absolute maximum ratings may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. 4. PD(max) = (TJ(max) - TA) JA, where JA depends upon the printed circuit layout. See "Applications Information." 5.Vout temperature coefficient is VOUT(worst case) (TJ(max) - TJ(min)) where TJ(max) is +125 and TJ(min) is 0 6. VDO = VIN - VOUT when VOUT decreases to 98% of its nominal output voltage with V IN = VOUT + 1V. 7. IGND is the quiescent current. IIN = I GND + IOUT. 8. VEN 0.8V, VIN 8V, and VOUT = 0V 9. For a 2.5V device, V IN = 2.250V (device is in dropout).
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5A Low-Voltage Low-Dropout Regulator
Application Information
LM39500/39501/39502
The LM39500/1 is a high-performance low-dropout voltage regulator suitable for moderate to high-current voltage regu-lator applications. Its 400mV dropout voltage at full load makes it especially valuable in battery-powered systems and as a high-efficiency noise filter in post-regulator applications. Unlike older NPN-pass transistor designs, where the mini-mum dropout voltage is limited by the base-to-emitter voltage drop and collector-toemitter saturation voltage, dropout per-formance of the PNP output of these devices is limited only by the low V CE saturation voltage.A trade-off for the low dropout voltage is a varying base drive requirement. The LM39500/1/2 regulator is fully protected from damage due to fault conditions. Current limiting is provided. This limiting is linear output current during overload conditions is constant. Thermal shutdown disables the device when the die temperature exceeds the maximum safe operating tem-perature. Transient protection allows device (and load) sur-vival even when the input voltage spikes above and below nominal. The output structure of these regulators allows voltages in excess of the desired output voltage to be applied without reverse current flow. Thermal Design Linear regulators are simple to use. The most complicated design parameters to consider are thermal characteristics.Thermal design requires four application-specific param-eters: *Maximum ambient temperature (TA) *Output Current (IOUT) *Output Voltage (VOUT) *Input Voltage (VIN) *Ground Current (IGND ) Calculate the power dissipation of the regulator from these numbers and the device parameters from this datasheet,where the ground current is taken from the data sheet. PD = (VIN - VOUT) IOUT + VIN*IGND The heat sink thermal resistance is determined by: SA=(TJMAX-TA)/PD -(JC+CS) where TJ (max) 125 and CS is between 0 and 2/W. The heat sink may be significantly reduced in applications where the minimum input voltage is known and is large compared with the dropout voltage. Use a series input resistor to drop excessive voltage and distribute the heat between this resistor and the regulator. The low dropout properties of Taejin regulators allow signifi-cant reductions in regulator power dissipation and the asso-ciated heat sink without compromising performance. When this technique is employed, a capacitor of at least 1.0F is needed directly between the input and regulator ground.Refer to Application Note 9 for further details and examples on thermal design and heat sink specification. Output Capacitor The LM39500/1/2 requires an output capacitor to maintain stability and improve transient response. Proper capacitor selection is important to ensure proper operation. The LM39500/1/2 output capacitor selection is dependent upon the ESR (equivalent series resistance) of the output capacitor to maintain stability. When the output capacitor is 47F or greater, the output capacitor should have less than 1 of ESR. This will improve transient response as well as promote stability. Ultralow ESR capacitors, such as ceramic chip capacitors may promote instability. These very low ESR levels may cause an oscillation and/or underdamped tran-sient response. A low-ESR solid tantalum capacitor works extremely well and provides good transient response and stability over temperature. Aluminum electrolytics can also be used, as long as the ESR of the capacitor is < 1.The value of the output capacitor can be increased without limit. Higher capacitance values help to improve transient response and ripple rejection and reduce output noise. Input Capacitor An input capacitor of 1uF or greater is recommended when the device is more than 4 inches away from the bulk ac supply capacitance, or when the supply is a battery. Small, surface-mount, ceramic chip capacitors can be used for the bypass-ing. Larger values will help to improve ripple rejection by bypassing the input to the regulator, further improving the integrity of the output voltage.Transient Response and 3.3V.
Fig 1. Capacitor Requirements
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5A Low-Voltage Low-Dropout Regulator
LM39500/39501/39502
Minimum Load Current The LM39500/1/2 regulator is specified between finite loads. If the output current is too small, leakage currents dominate and the output voltage rises. A 10mA minimum load current is necessary for proper regulation. Transient Response and 3.3V to 2.5V Conversion The LM39500/1/2 has excellent transient response to varia-tions in input voltage and load current. The device has been designed to respond quickly to load current variations and input voltage variations. Large output capacitors are not required to obtain this performance. A standard 47F output capacitor, preferably tantalum, is all that is required. Larger values help to improve performance even further. By virtue of its low-dropout voltage, this device does not saturate into dropout as readily as similar NPN-based designs. When converting from 3.3V to 2.5V, the NPN-based regulators are already operating in dropout, with typical dropout requirements of 1.2V or greater. To convert down to 2.5V without operating in dropout, NPN-based regulators require an input voltage of 3.7V at the very least. The LM39500/1/2 regulator will provide excellent performance with an input as low as 3.0V. This gives the PNP-based regulators a distinct advantage over older, NPN-based linear regulators does not have the headroom to dothis conversion.
Error Flag The LM39501 version features an error flag circuit which monitors the output voltage and signals an error condition when the voltage drops 5% below the nominal output voltage. The error flag is an open-collector output that can sink 10mA during a fault condition. Low output voltage can be caused by a number of problems, including an overcurrent fault (device in current limit) or low input voltage. The flag is inoperative during overtemperature shutdown. Enable Input The LM39501 version features an enable input for on/off control of the device. Its shutdown state draws "zero" current (only microamperes of leakage). The enable input is TTL/ CMOS compatible for simple logic interface, but can be connected to up to 20V. Adjustable Regulator Design The LM39502 allows programming the output voltage any-where between 1.25V and the 16V maximum operating rating of the family. Two resistors are used. Resistors can be quite large, up to 1M, because of the very high input impedance and low bias current of the sense comparator: The resistor values are calculated by : R1=R2(Vout/1.250-
1)
Where VO is the desired output voltage. Figure 1 shows component definition. Applications with widely varying load lh i d h ii ld i df i ( bl )
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