LT3014

LT3014 20mA, 3V to 80V Low Dropout Micropower Linear Regulator FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Wide Input Voltage Range: 3V to 80V Low Quiescent Current: 7µA Low Dropout Voltage: 350mV Output Current: 20mA LT3014HV Survives 100V Transients (2ms) No Protection Diodes Needed Adjustable Output from 1.22V to 60V 1µA Quiescent Current in Shutdown Stable with 0.47µF Output Capacitor Stable with Aluminum, Tantalum or Ceramic Capacitors Reverse-Battery Protection No Reverse Current Flow from Output Thermal Limiting Available in 5-Lead ThinSOTTM and 8-Lead DFN Packages The LT®3014 is a high voltage, micropower low dropout linear regulator. The device is capable of supplying 20mA of output current with a dropout voltage of 350mV. Designed for use in battery-powered or high voltage systems, the low quiescent current (7µA operating and 1µA in shutdown) makes the LT3014 an ideal choice. Quiescent current is also well controlled in dropout. Other features of the LT3014 include the ability to operate with very small output capacitors. The regulators are stable with only 0.47µF on the output while most older devices require between 10µF and 100µF for stability. Small ceramic capacitors can be used without the necessary addition of ESR as is common with other regulators. Internal protection circuitry includes reverse-battery protection, current limiting, thermal limiting and reverse current protection. The device is available as an adjustable device with a 1.22V reference voltage. The LT3014 regulator is available in the 5-lead ThinSOT and 8-lead DFN packages. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 6118263, 6144250. APPLICATIO S ■ ■ ■ ■ Low Current High Voltage Regulators Regulator for Battery-Powered Systems Telecom Applications Automotive Applications TYPICAL APPLICATIO 400 5V Supply with Shutdown IN VIN 5.4V TO 80V 1µF OUT LT3014 SHDN GND ADJ 1.27M 3014 TA01 350 3.92M VOUT 5V 20mA 0.47µF DROPOUT VOLTAGE (mV) 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14 16 18 20 OUTPUT CURRENT (mA) 3014 TA02 VSHDN OUTPUT 2.0V ON U Dropout Voltage 3014fb U U 1 LT3014 ABSOLUTE AXI U RATI GS (Note 1) Storage Temperature Range ThinSOT Package......................... –65°C to 150°C DFN Package ............................... –65°C to 125°C Operating Junction Temperature Range (Notes 3, 10, 11) ......................... –40°C to 125°C Lead Temperature, SOT-23 (Soldering, 10 sec) ..................................... 300°C IN Pin Voltage, Operating ................................. ±80V Transient (2ms Survival, LT3014HV) .............. +100V OUT Pin Voltage ............................................... ±60V IN to OUT Differential Voltage ........................... ± 80V ADJ Pin Voltage .................................................. ± 7V SHDN Pin Input Voltage ................................... ±80V Output Short-Circuit Duration ..................... Indefinite PACKAGE/ORDER I FOR ATIO TOP VIEW IN 1 GND 2 SHDN 3 5 OUT 4 ADJ S5 PACKAGE 5-LEAD PLASTIC SOT-23 TJMAX = 125°C, θJA = 150°C/ W θJC = 25°C/ W MEASURED AT PIN 2. SEE APPLICATIONS INFORMATION SECTION. ORDER PART NUMBER LT3014ES5 LT3014HVES5 S5 PART MARKING LTBMF LTBRS Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25°C. PARAMETER Minimum Input Voltage ADJ Pin Voltage (Notes 2, 3) Line Regulation Load Regulation CONDITIONS ILOAD = 20mA VIN = 3.3V, ILOAD = 100µA 3.3V < VIN < 80V, 100µA < ILOAD < 20mA ∆VIN = 3.3V to 80V, ILOAD = 100µA (Note 2) VIN = 3.3V, ∆ILOAD = 100µA to 20mA (Note 2) VIN = 3.3V, ∆ILOAD = 100µA to 20mA ● ● ● ● 2 U U W WW U W TOP VIEW OUT ADJ NC GND 1 2 3 4 9 8 7 6 5 IN NC NC SHDN DD PACKAGE 8-LEAD (3mm × 3mm) PLASTIC DFN EXPOSED PAD IS GND (PIN 9) MUST BE SOLDERED TO PCB TJMAX = 125°C, θJA = 40°C/ W θJC = 10°C/ W MEASURED AT PIN 9. ORDER PART NUMBER LT3014EDD LT3014HVEDD DD PART MARKING LBMG LBRT MIN 1.200 1.180 TYP 3 1.220 1.220 1 13 MAX 3.3 1.240 1.260 10 25 40 UNITS V V V mV mV mV 3014fb LT3014 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25°C. PARAMETER Dropout Voltage VIN = VOUT(NOMINAL) (Notes 4, 5) CONDITIONS ILOAD = 100µA ILOAD = 100µA ILOAD = 1mA ILOAD = 1mA ILOAD = 10mA ILOAD = 10mA ILOAD = 20mA ILOAD = 20mA GND Pin Current VIN = VOUT(NOMINAL) (Notes 4, 6) ILOAD = 0mA ILOAD = 100µA ILOAD = 1mA ILOAD = 10mA ILOAD = 20mA COUT = 0.47µF, ILOAD = 20mA, BW = 10Hz to 100kHz (Note 7) VOUT = Off to On VOUT = On to Off VSHDN = 0V VSHDN = 6V VIN = 6V, VSHDN = 0V VIN = 7V(Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 20mA VIN = 7V, VOUT = 0V VIN = 3.3V, ∆VOUT = – 0.1V (Note 2) VIN = – 80V, VOUT = 0V VOUT = 1.22V, VIN < 1.22V (Note 2) ● ● ● ● ● ● ● ● MIN TYP 120 200 MAX 180 250 270 360 350 450 410 570 20 30 100 450 1000 10 2 4 1 4 UNITS mV mV mV mV mV mV mV mV µA µA µA µA µA µVRMS nA V V µA µA µA dB mA mA ● 300 ● 350 ● ● ● ● ● ● 7 12 40 250 650 115 4 0.25 1.3 1.3 1 0 1 60 25 70 70 Output Voltage Noise ADJ Pin Bias Current Shutdown Threshold SHDN Pin Current (Note 8) Quiescent Current in Shutdown Ripple Rejection Current Limit Input Reverse Leakage Current Reverse Output Current (Note 9) 6 2 4 mA µA Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT3014 is tested and specified for these conditions with the ADJ pin connected to the OUT pin. Note 3: Operating conditions are limited by maximum junction temperature. The regulated output voltage specification will not apply for all possible combinations of input voltage and output current. When operating at maximum input voltage, the output current range must be limited. When operating at maximum output current, the input voltage range must be limited. Note 4: To satisfy requirements for minimum input voltage, the LT3014 is tested and specified for these conditions with an external resistor divider (249k bottom, 392k top) for an output voltage of 3.3V. The external resistor divider adds a 5µA DC load on the output. Note 5: Dropout voltage is the minimum input to output voltage differential needed to maintain regulation at a specified output current. In dropout, the output voltage is equal to (VIN – VDROPOUT). Note 6: GND pin current is tested with VIN = VOUT (nominal) and a current source load. This means the device is tested while operating in its dropout region. This is the worst-case GND pin current. The GND pin current decreases slightly at higher input voltages. Note 7: ADJ pin bias current flows into the ADJ pin. Note 8: SHDN pin current flows out of the SHDN pin. Note 9: Reverse output current is tested with the IN pin grounded and the OUT pin forced to the rated output voltage. This current flows into the OUT pin and out of the GND pin. Note 10: The LT3014E is guaranteed to meet performance specifications from 0°C to 125°C operating junction temperature. Specifications over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. Note 11: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. 3014fb 3 LT3014 TYPICAL PERFOR A CE CHARACTERISTICS Typical Dropout Voltage 500 450 DROPOUT VOLTAGE (mV) DROPOUT VOLTAGE (mV) DROPOUT VOLTAGE (mV) 400 350 300 250 200 150 100 50 0 TJ = 125°C TJ = 25°C 0 2 4 6 8 10 12 14 16 18 20 OUTPUT CURRENT (mA) 3014 G01 Quiescent Current 16 14 QUIESCENT CURRENT (µA) ADJ PIN VOLTAGE (V) 12 10 8 6 4 2 0 – 50 – 25 0 VSHDN = 0V 50 75 25 TEMPERATURE (°C) 100 125 VSHDN = VIN 1.230 1.225 1.220 QUIESCENT CURRENT (µA) VIN = 6V RL = ∞ IL = 0 GND Pin Current 1000 TJ = 25°C 900 *FOR VOUT = 1.22V 800 GND PIN CURRENT (µA) 1000 700 600 500 400 300 200 100 0 0 1 2 RL = 61Ω IL = 20mA* SHDN PIN THRESHOLD (V) GND PIN CURRENT (µA) RL = 122Ω IL = 10mA* RL = 1.22k IL = 1mA* 34567 INPUT VOLTAGE (V) 8 9 10 4 UW 3014 G04 3014 G07 Guaranteed Dropout Voltage 600 500 400 300 200 100 0 0 2 4 6 8 10 12 14 16 18 20 OUTPUT CURRENT (mA) 3014 G02 Dropout Voltage 500 450 = TEST POINTS TJ ≤ 125°C 400 350 300 250 200 150 100 50 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 IL = 1mA IL = 100µA IL = 20mA IL = 10mA TJ ≤ 25°C 3014 G03 ADJ Pin Voltage 1.240 1.235 Quiescent Current 16 TJ = 25°C 14 RL = ∞ VOUT = 1.22V 12 10 8 6 4 2 0 VSHDN = 0V 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 VSHDN = VIN IL = 100µA 1.215 1.210 1.205 1.200 – 50 – 25 0 75 50 25 TEMPERATURE (°C) 100 125 3014 G05 3014 G06 GND Pin Current vs ILOAD VIN = 3.3V 900 TJ = 25°C = 1.22V V 800 OUT 700 600 500 400 300 200 100 0 0 2 4 6 8 10 12 14 16 18 20 OUTPUT CURRENT (mA) 3014 G08 SHDN Pin Threshold 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 3014 G09 3014fb LT3014 TYPICAL PERFOR A CE CHARACTERISTICS SHDN Pin Current 1.2 TJ = 25°C CURRENT FLOWS 1.0 OUT OF SHDN PIN 1.2 1.0 0.8 0.6 0.4 0.2 ADJ PIN BIAS CURRENT (nA) SHDN PIN CURRENT (µA) SHDN PIN CURRENT (µA) 0.8 0.6 0.4 0.2 0 0 0.5 2.5 3 1 1.5 2 SHDN PIN VOLTAGE (V) Current Limit 80 100 90 80 REVERSE OUTPUT CURRENT (µA) VOUT = 0V 70 TJ = 25°C CURRENT LIMIT (mA) CURRENT LIMIT (mA) 60 50 40 30 20 10 0 0 2 4 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 3014 G13 Reverse Output Current 8 REVERSE OUTPUT CURRENT (µA) 7 6 5 4 3 2 1 VIN = 0V VOUT = VADJ = 1.22V RIPPLE REJECTION (dB) 66 64 62 60 58 56 – 50 – 25 0 50 75 25 TEMPERATURE (°C) 100 125 RIPPLE REJECTION (dB) 0 – 50 – 25 0 50 75 25 TEMPERATURE (°C) UW 3.5 4 3014 G10 SHDN Pin Current 1.6 VSHDN = 0V 1.4 CURRENT FLOWS OUT OF SHDN PIN 14 12 10 8 6 4 2 ADJ Pin Bias Current 0 – 50 – 25 0 50 75 25 TEMPERATURE (°C) 100 125 0 – 50 – 25 0 50 75 25 TEMPERATURE (°C) 100 125 3014 G11 3014 G12 Current Limit VIN = 7V VOUT = 0V Reverse Output Current 50 TJ = 25°C 45 VIN = 0V = VADJ V 40 OUT 35 30 25 20 15 10 5 0 CURRENT FLOWS INTO OUTPUT PIN ADJ PIN ESD CLAMP 70 60 50 40 30 20 10 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 0 1 2 345678 OUTPUT VOLTAGE (V) 9 10 3014 G14 3014 G15 Input Ripple Rejection 72 VIN = 7V + 0.5VP-P 70 RIPPLE AT f = 120Hz IL = 20mA 68 80 70 60 50 40 30 20 10 Input Ripple Rejection VIN = 7V + 50mVRMS RIPPLE IL = 20mA COUT = 4.7µF COUT = 0.47µF 100 1k 10k FREQUENCY (Hz) 100k 1M 3014 G18 100 125 0 10 3014 G16 3014 G17 3014fb 5 LT3014 TYPICAL PERFOR A CE CHARACTERISTICS Minimum Input Voltage 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 –50 –25 LOAD REGULATION (mV) ILOAD = 20mA –5 –10 –15 –20 –25 –30 –35 25 75 0 50 TEMPERATURE (°C) 100 125 OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) MINIMUM INPUT VOLTAGE (V) 10Hz to 100kHz Output Noise OUTPUT VOLTAGE DEVIATION (V) VOUT 200µV/DIV LOAD CURRENT (mA) COUT = 0.47µF IL = 20mA VOUT = 1.22V PI FU CTIO S (SOT-23 Package/DD Package) IN (Pin 1/Pin 8): Input. Power is supplied to the device through the IN pin. A bypass capacitor is required on this pin if the device is more than six inches away from the main input filter capacitor. In general, the output impedance of a battery rises with frequency, so it is advisable to include a bypass capacitor in battery-powered circuits. A bypass capacitor in the range of 0.1µF to 10µF is sufficient. The LT3014 is designed to withstand reverse voltages on the IN pin with respect to ground and the OUT pin. In the case of a reversed input, which can happen if a battery is plugged in backwards, the LT3014 will act as if there is a diode in series with its input. There will be no reverse current flow into the LT3014 and no reverse voltage will 6 UW 3014 G19 Load Regulation 0 ∆IL = 100µA TO 20mA VOUT = 1.22V 10 Output Noise Spectral Density COUT = 0.47µF IL = 20mA VOUT = 1.22V 1 0.1 –40 – 50 – 25 0 25 50 75 100 125 0.01 10 100 1k 10k FREQUENCY (Hz) 100k 3014 G21 TEMPERATURE (°C) 3014 G20 Transient Response 0.04 0.02 0 –0.02 –0.04 VIN = 7V VOUT = 5V CIN = COUT = 0.47µF CERAMIC ∆ILOAD = 1mA TO 5mA 6 4 2 0 0 200 600 400 TIME (µs) 800 1000 3014 G23 1ms/DIV 3014 G22 U U U appear at the load. The device will protect both itself and the load. GND (Pin 2/Pins 4, 9): Ground. SHDN (Pin 3/Pin 5): Shutdown. The SHDN pin is used to put the LT3014 into a low power shutdown state. The output will be off when the SHDN pin is pulled low. The SHDN pin can be driven either by 5V logic or opencollector logic with a pull-up resistor. The pull-up resistor is only required to supply the pull-up current of the opencollector gate, normally several microamperes. If unused, the SHDN pin must be tied to IN or to a logic high. 3014fb LT3014 PI FU CTIO S ADJ (Pin 4/Pin 2): Adjust. This is the input to the error amplifier. This pin is internally clamped to ±7V. It has a bias current of 4nA which flows into the pin (see curve of ADJ Pin Bias Current vs Temperature in the Typical Performance Characteristics). The ADJ pin voltage is 1.22V referenced to ground, and the output voltage range is 1.22V to 60V. APPLICATIO S I FOR ATIO The LT3014 is a 20mA high voltage low dropout regulator with micropower quiescent current and shutdown. The device is capable of supplying 20mA at a dropout voltage of 350mV. The low operating quiescent current (7µA) drops to 1µA in shutdown. In addition to the low quiescent current, the LT3014 incorporates several protection features which make it ideal for use in battery-powered systems. The device is protected against both reverse input and reverse output voltages. In battery backup applications where the output can be held up by a backup battery when the input is pulled to ground, the LT3014 acts like it has a diode in series with its output and prevents reverse current flow. Adjustable Operation The LT3014 has an output voltage range of 1.22V to 60V. The output voltage is set by the ratio of two external resistors as shown in Figure 2. The device servos the output to maintain the voltage at the adjust pin at 1.22V referenced to ground. The current in R1 is then equal to 1.22V/R1 and the current in R2 is the current in R1 plus the ADJ pin bias current. The ADJ pin bias current, 4nA at 25°C, flows through R2 into the ADJ pin. The output voltage can be calculated using the formula in Figure 1. The value of R1 should be less than 1.62M to minimize errors in the output voltage caused by the ADJ pin bias current. Note that in shutdown the output is turned off and the divider current will be zero. The device is tested and specified with the ADJ pin tied to the OUT pin and a 5µA DC load (unless otherwise specified) for an output voltage of 1.22V. Specifications for output voltages greater U W UU U U U (SOT-23 Package/DD Package) OUT (Pin 5/Pin 1): Output. The output supplies power to the load. A minimum output capacitor of 0.47µF is required to prevent oscillations. Larger output capacitors will be required for applications with large transient loads to limit peak voltage transients. See the Applications Information section for more information on output capacitance and reverse output characteristics. than 1.22V will be proportional to the ratio of the desired output voltage to 1.22V (VOUT/1.22V). For example, load regulation for an output current change of 1mA to 20mA is –13mV typical at VOUT = 1.22V. At VOUT = 12V, load regulation is: (12V/1.22V) • (–13mV) = –128mV IN VIN OUT LT3014 ADJ GND R1 R2 + VOUT VOUT = 1.22V • 1 + R2 + (IADJ)(R2) R1 VADJ = 1.22V IADJ = 4nA AT 25°C OUTPUT RANGE = 1.22V TO 60V () 3014 F01 Figure 1. Adjustable Operation Output Capacitance and Transient Response The LT3014 is designed to be stable with a wide range of output capacitors. The ESR of the output capacitor affects stability, most notably with small capacitors. A minimum output capacitor of 0.47µF with an ESR of 3Ω or less is recommended to prevent oscillations. The LT3014 is a micropower device and output transient response will be a function of output capacitance. Larger values of output capacitance decrease the peak deviations and provide improved transient response for larger load current changes. Bypass capacitors, used to decouple individual components powered by the LT3014, will increase the effective output capacitor value. 3014fb 7 LT3014 APPLICATIO S I FOR ATIO Extra consideration must be given to the use of ceramic capacitors. Ceramic capacitors are manufactured with a variety of dielectrics, each with different behavior across temperature and applied voltage. The most common dielectrics used are Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high capacitances in a small package, but exhibit strong voltage and temperature coefficients as shown in Figures 2 and 3. When used with a 5V regulator, a 10µF Y5V capacitor can exhibit an effective value as low as 1µF to 2µF over the operating temperature range. The X5R and X7R dielectrics result in more stable characteristics and are more suitable for use as the output capacitor. The X7R type has better stability across temperature, while the X5R is less expensive and is available in higher values. Voltage and temperature coefficients are not the only sources of problems. Some ceramic capacitors have a piezoelectric response. A piezoelectric device generates voltage across its terminals due to mechanical stress, 20 0 CHANGE IN VALUE (%) BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF CHANGE IN VALUE (%) X5R –20 –40 –60 Y5V –80 –100 0 2 4 8 6 10 12 DC BIAS VOLTAGE (V) 14 16 3014 F02 Figure 2. Ceramic Capacitor DC Bias Characteristics 8 U similar to the way a piezoelectric accelerometer or microphone works. For a ceramic capacitor the stress can be induced by vibrations in the system or thermal transients. Thermal Considerations The power handling capability of the device will be limited by the maximum rated junction temperature (125°C). The power dissipated by the device will be made up of two components: 1. Output current multiplied by the input/output voltage differential: IOUT • (VIN – VOUT) and, 2. GND pin current multiplied by the input voltage: IGND • VIN. The GND pin current can be found by examining the GND Pin Current curves in the Typical Performance Characteristics. Power dissipation will be equal to the sum of the two components listed above. 40 20 0 X5R –20 –40 –60 –80 Y5V BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF –100 50 25 75 –50 –25 0 TEMPERATURE (°C) 100 125 3014 F03 W UU Figure 3. Ceramic Capacitor Temperature Characteristics 3014fb LT3014 APPLICATIO S I FOR ATIO The LT3014 regulator has internal thermal limiting designed to protect the device during overload conditions. For continuous normal conditions the maximum junction temperature rating of 125°C must not be exceeded. It is important to give careful consideration to all sources of thermal resistance from junction to ambient. Additional heat sources mounted nearby must also be considered. For surface mount devices, heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper traces. Copper board stiffeners and plated through-holes can also be used to spread the heat generated by power devices. The following table lists thermal resistance for several different board sizes and copper areas. All measurements were taken in still air on 3/32" FR-4 board with one ounce copper. Table 1. SOT-23 Measured Thermal Resistance COPPER AREA TOPSIDE 2500 sq mm 1000 sq mm 225 sq mm 100 sq mm 50 sq mm BACKSIDE 2500 sq mm 2500 sq mm 2500 sq mm 2500 sq mm 2500 sq mm BOARD AREA 2500 sq mm 2500 sq mm 2500 sq mm 2500 sq mm 2500 sq mm THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 125°C/W 125°C/W 130°C/W 135°C/W 150°C/W Table 2. DFN Measured Thermal Resistance COPPER AREA TOPSIDE 2500 sq mm 1000 sq mm 225 sq mm 100 sq mm BACKSIDE 2500 sq mm 2500 sq mm 2500 sq mm 2500 sq mm BOARD AREA 2500 sq mm 2500 sq mm 2500 sq mm 2500 sq mm THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 40°C/W 45°C/W 50°C/W 62°C/W For the DFN package, the thermal resistance junction-tocase (θJC), measured at the exposed pad on the back of the die, is 16°C/W. U Continuous operation at large input/output voltage differentials and maximum load current is not practical due to thermal limitations. Transient operation at high input/ output differentials is possible. The approximate thermal time constant for a 2500sq mm 3/32" FR-4 board with maximum topside and backside area for one ounce copper is 3 seconds. This time constant will increase as more thermal mass is added (i.e. vias, larger board, and other components). For an application with transient high power peaks, average power dissipation can be used for junction temperature calculations as long as the pulse period is significantly less than the thermal time constant of the device and board. Calculating Junction Temperature Example 1: Given an output voltage of 5V, an input voltage range of 24V to 30V, an output current range of 0mA to 20mA, and a maximum ambient temperature of 50°C, what will the maximum junction temperature be? The power dissipated by the device will be equal to: IOUT(MAX) • (VIN(MAX) – VOUT) + (IGND • VIN(MAX)) where: IOUT(MAX) = 20mA VIN(MAX) = 30V IGND at (IOUT = 20mA, VIN = 30V) = 0.55mA So: P = 20mA • (30V – 5V) + (0.55mA • 30V) = 0.52W The thermal resistance for the DFN package will be in the range of 40°C/W to 62°C/W depending on the copper area. So the junction temperature rise above ambient will be approximately equal to: 0.52W • 50°C/W = 26°C 3014fb W UU 9 LT3014 APPLICATIO S I FOR ATIO The maximum junction temperature will then be equal to the maximum junction temperature rise above ambient plus the maximum ambient temperature or: TJMAX = 50°C + 26°C = 76°C Example 2: Given an output voltage of 5V, an input voltage of 48V that rises to 72V for 5ms(max) out of every 100ms, and a 5mA load that steps to 20mA for 50ms out of every 250ms, what is the junction temperature rise above ambient? Using a 500ms period (well under the time constant of the board), power dissipation is as follows: P1(48V in, 5mA load) = 5mA • (48V – 5V) + (100µA • 48V) = 0.22W P2(48V in, 20mA load) = 20mA • (48V – 5V) + (0.55mA • 48V) = 0.89W P3(72V in, 5mA load) = 5mA • (72V – 5V) + (100µA • 72V) = 0.34W P4(72V in, 20mA load) = 20mA • (72V – 5V) + (0.55mA • 72V) = 1.38W Operation at the different power levels is as follows: 76% operation at P1, 19% for P2, 4% for P3, and 1% for P4. PEFF = 76%(0.22W) + 19%(0.89W) + 4%(0.34W) + 1%(1.38W) = 0.36W With a thermal resistance in the range of 40°C/W to 62°C/W, this translates to a junction temperature rise above ambient of 20°C. 10 U Protection Features The LT3014 incorporates several protection features which make it ideal for use in battery-powered circuits. In addition to the normal protection features associated with monolithic regulators, such as current limiting and thermal limiting, the device is protected against reverse-input voltages, and reverse voltages from output to input. Current limit protection and thermal overload protection are intended to protect the device against current overload conditions at the output of the device. For normal operation, the junction temperature should not exceed 125°C. The input of the device will withstand reverse voltages of 80V. Current flow into the device will be limited to less than 6mA (typically less than 100µA) and no negative voltage will appear at the output. The device will protect both itself and the load. This provides protection against batteries which can be plugged in backward. The ADJ pin can be pulled above or below ground by as much as 7V without damaging the device. If the input is left open circuit or grounded, the ADJ pin will act like an open circuit when pulled below ground, and like a large resistor (typically 100k) in series with a diode when pulled above ground. If the input is powered by a voltage source, pulling the ADJ pin below the reference voltage will cause the device to current limit. This will cause the output to go to an unregulated high voltage. Pulling the ADJ pin above the reference voltage will turn off all output current. 3014fb W UU LT3014 APPLICATIO S I FOR ATIO In situations where the ADJ pin is connected to a resistor divider that would pull the ADJ pin above its 7V clamp voltage if the output is pulled high, the ADJ pin input current must be limited to less than 5mA. For example, a resistor divider is used to provide a regulated 1.5V output from the 1.22V reference when the output is forced to 60V. The top resistor of the resistor divider must be chosen to limit the current into the ADJ pin to less than 5mA when the ADJ pin is at 7V. The 53V difference between the OUT and ADJ pins divided by the 5mA maximum current into the ADJ pin yields a minimum top resistor value of 10.6k. In circuits where a backup battery is required, several different input/output conditions can occur. The output voltage may be held up while the input is either pulled to ground, pulled to some intermediate voltage, or is left 50 TJ = 25°C 45 VIN = 0V = VADJ V 40 OUT 35 30 25 20 15 10 5 0 0 1 2 CURRENT FLOWS INTO OUTPUT PIN REVERSE OUTPUT CURRENT (µA) Figure 4. Reverse Output Current U open circuit. Current flow back into the output will follow the curve shown in Figure 4. The rise in reverse output current above 7V occurs from the breakdown of the 7V clamp on the ADJ pin. With a resistor divider on the regulator output, this current will be reduced depending on the size of the resistor divider. When the IN pin of the LT3014 is forced below the OUT pin or the OUT pin is pulled above the IN pin, input current will typically drop to less than 2µA. This can happen if the input of the LT3014 is connected to a discharged (low voltage) battery and the output is held up by either a backup battery or a second regulator circuit. The state of the SHDN pin will have no effect on the reverse output current when the output is pulled above the input. ADJ PIN ESD CLAMP 345678 OUTPUT VOLTAGE (V) 9 10 3014 F04 W UU 3014fb 11 LT3014 TYPICAL APPLICATIO S 5V Buck Converter with Low Current Keep Alive Backup D2 D1N914 6 VIN 5.5V* TO 60V BOOST 4 C3 4.7µF 100V CERAMIC VIN LT1766 15 14 SHDN SYNC GND BIAS FB VC CC 1nF 10 12 R1 15.4k R2 4.99k SW 2 C2 0.33µF OPERATING CURRENT LOW HIGH EFFICIENCY (%) 12 U L1† 15µH D1 10MQ060N VOUT 5V 1A/20mA + C1 100µF 10V SOLID TANTALUM 1, 8, 9, 16 11 IN LT3014 SHDN GND OUT 3.92M ADJ 1.27M * FOR INPUT VOLTAGES BELOW 7.5V, SOME RESTRICTIONS MAY APPLY † INCREASE L1 TO 30µH FOR LOAD CURRENTS ABOVE 0.6A AND TO 60µH ABOVE 1A 3014 TA03 Buck Converter Efficiency vs Load Current 100 VOUT = 5V L = 68µH VIN = 10V 90 VIN = 42V 80 70 60 50 0 0.25 0.75 1.00 0.50 LOAD CURRENT (A) 1.25 3014 TA04 3014fb LT3014 TYPICAL APPLICATIO S LT3014 Automotive Application IN 1µ F NO PROTECTION DIODE NEEDED! LT3014 SHDN GND OFF ON ADJ R2 OUT R1 1µ F LOAD: CLOCK, SECURITY SYSTEM ETC VIN 12V (LATER 42V) + VIN 48V (72V TRANSIENT) 1µ F OFF ON Constant Brightness for Indicator LED over Wide Input Voltage Range RETURN 1µF OFF ON U LT3014 Telecom Application IN LT3014 SHDN GND OUT R1 NO PROTECTION DIODE NEEDED! R2 1µ F LOAD: SYSTEM MONITOR ETC + – ADJ BACKUP BATTERY 3014 TA05 IN OUT LT3014 1µF RSET 3014 TA06 SHDN GND ADJ –48V ILED = 1.22V/RSET –48V CAN VARY FROM –3.3V TO –80V 3014fb 13 LT3014 PACKAGE DESCRIPTIO 0.62 MAX 0.95 REF 3.85 MAX 2.62 REF RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.20 BSC 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 0.09 – 0.20 (NOTE 3) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. JEDEC PACKAGE REFERENCE IS MO-193 14 U S5 Package 5-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1635) 2.90 BSC (NOTE 4) 1.22 REF 1.4 MIN 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE 0.30 – 0.45 TYP 5 PLCS (NOTE 3) 0.95 BSC 0.80 – 0.90 0.01 – 0.10 1.90 BSC S5 TSOT-23 0302 REV B 3014fb LT3014 PACKAGE DESCRIPTIO U DD Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) 0.675 ± 0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ± 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 5 0.38 ± 0.10 8 3.00 ± 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6) (DD) DFN 1203 3.5 ± 0.05 1.65 ± 0.05 2.15 ± 0.05 (2 SIDES) 1.65 ± 0.10 (2 SIDES) 0.200 REF 0.75 ± 0.05 4 0.25 ± 0.05 2.38 ± 0.10 (2 SIDES) 1 0.50 BSC 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON TOP AND BOTTOM OF PACKAGE 3014fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 15 LT3014 RELATED PARTS PART NUMBER LT1129 LT1175 LT1185 LT1761 LT1762 LT1763 DESCRIPTION 700mA, Micropower, LDO 500mA, Micropower Negative LDO 3A, Negative LDO 100mA, Low Noise Micropower, LDO 150mA, Low Noise Micropower, LDO 500mA, Low Noise Micropower, LDO COMMENTS VIN: 4.2V to 30V, VOUT(MIN) = 3.75V, VDO = 0.4V, IQ = 50µA, ISD = 16µA, DD, SOT-223, S8, TO220, TSSOP-20 Packages VIN: –20V to –4.3V, VOUT(MIN) = – 3.8V, VDO = 0.50V, IQ = 45µA, ISD = 10µA, DD, SOT-223, S8 Packages VIN: –35V to –4.2V, VOUT(MIN) = – 2.40V, VDO = 0.80V, IQ = 2.5mA, ISD