LT3012HFE-PBF

FEATURES n n n n n n n n n n n n n LT3012 250mA, 4V to 80V Low Dropout Micropower Linear Regulator DESCRIPTION The LT®3012 is a high voltage, micropower low dropout linear regulator. The device is capable of supplying 250mA of output current with a dropout voltage of 400mV. Designed for use in battery-powered or high voltage systems, the low quiescent current (40μA operating and 1μA in shutdown) makes the LT3012 an ideal choice. Quiescent current is also well controlled in dropout. Other features of the LT3012 include the ability to operate with very small output capacitors. The regulator is stable with only 3.3μF on the output while most older devices require between 10μF and 100μF for stability. Small ceramic capacitors can be used without any need for series resistance (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 with an adjustable output with a 1.24V reference voltage. The LT3012 regulator is available in the 16-lead TSSOP and 12 pin low profile (0.75mm) (4mm × 3mm) DFN packages with an exposed pad for enhanced thermal handling capability. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Wide Input Voltage Range: 4V to 80V Low Quiescent Current: 40μA Low Dropout Voltage: 400mV Output Current: 250mA No Protection Diodes Needed Adjustable Output from 1.24V to 60V 1μA Quiescent Current in Shutdown Stable with 3.3μF Output Capacitor Stable with Aluminum, Tantalum or Ceramic Capacitors Reverse-Battery Protection No Reverse Current Flow from Output to Input Thermal Limiting Thermally Enhanced 16-Lead TSSOP and 12-Pin (4mm × 3mm) DFN Packages APPLICATIONS n n n n Low Current High Voltage Regulators Regulator for Battery-Powered Systems Telecom Applications Automotive Applications TYPICAL APPLICATION 5V Supply with Shutdown 400 IN VIN 5.4V TO 80V 1μF OUT LT3012 SHDN GND ADJ 249k 3012 TA01 Dropout Voltage VOUT 5V 250mA 3.3μF 350 DROPOUT VOLTAGE (mV) 300 250 200 150 100 50 0 0 50 100 150 200 OUTPUT CURRENT (mA) 250 3012 TA02 750k VSHDN 2.0V OUTPUT OFF ON 3012fd 1 LT3012 ABSOLUTE MAXIMUM RATINGS (Note 1) IN Pin Voltage .........................................................±80V OUT Pin Voltage ......................................................±60V IN to OUT Differential Voltage .................................±80V ADJ Pin Voltage ........................................................±7V SHDN Pin Input Voltage ..........................................±80V Output Short-Circuit Duration .......................... Indefinite Storage Temperature Range TSSOP Package ................................. –65°C to 150°C DFN Package...................................... –65°C to 125°C Operating Junction Temperature Range (Notes 3, 10, 11) LT3012E ............................................. –40°C to 125°C LT3012HFE......................................... –40°C to 140°C Lead Temperature (FE16 Soldering, 10 sec) ......... 300°C PIN CONFIGURATION TOP VIEW TOP VIEW GND NC OUT OUT ADJ GND NC 1 2 3 4 5 6 13 12 NC 11 IN 10 IN 9 8 7 NC SHDN NC NC OUT OUT ADJ GND NC GND DE PACKAGE 12-LEAD (4mm × 3mm) PLASTIC DFN TJMAX = 125°C, θJA = 40°C/W, θJC = 16°C/W EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB 1 2 3 4 5 6 7 8 17 16 GND 15 NC 14 IN 13 IN 12 NC 11 SHDN 10 NC 9 GND FE PACKAGE 16-LEAD PLASTIC TSSOP TJMAX = 140°C, θJA = 40°C/W, θJC = 16°C/W EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH LT3012EDE#PBF LT3012EFE#PBF LT3012HFE#PBF LEAD BASED FINISH LT3012EDE LT3012EFE LT3012HFE TAPE AND REEL LT3012EDE#TRPBF LT3012EFE#TRPBF LT3012HFE#TRPBF TAPE AND REEL LT3012EDE#TR LT3012EFE#TR LT3012HFE#TR PART MARKING 3012 3012EFE 3012HFE PART MARKING 3012 3012EFE 3012HFE PACKAGE DESCRIPTION 12-Lead (4mm × 3mm) Plastic DFN 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP PACKAGE DESCRIPTION 12-Lead (4mm × 3mm) Plastic DFN 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C –40°C to 140°C TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C –40°C to 140°C Consult LTC Marketing for parts specified with wider operating temperature ranges. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 3012fd 2 LT3012 ELECTRICAL CHARACTERISTICS PARAMETER Minimum Input Voltage ADJ Pin Voltage (Notes 2, 3) Line Regulation Load Regulation (Note 2) Dropout Voltage VIN = VOUT(NOMINAL) (Notes 4, 5) CONDITIONS ILOAD = 250mA VIN = 4V, ILOAD = 1mA 4.75V < VIN < 80V, 1mA < ILOAD < 250mA ΔVIN = 4V to 80V, ILOAD = 1mA (Note 2) VIN = 4.75V, ΔILOAD = 1mA to 250mA VIN = 4.75V, ΔILOAD = 1mA to 250mA ILOAD = 10mA ILOAD = 10mA ILOAD = 50mA ILOAD = 50mA ILOAD = 250mA ILOAD = 250mA GND Pin Current VIN = 4.75V (Notes 4, 6) Output Voltage Noise ADJ Pin Bias Current Shutdown Threshold SHDN Pin Current (Note 8) Quiescent Current in Shutdown Ripple Rejection Current Limit Reverse Output Current (Note 9) ILOAD = 0mA ILOAD = 100mA ILOAD = 250mA COUT = 10μF ILOAD = 250mA, 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 = 250mA VIN = 7V, VOUT = 0V VIN = 4.75V, ΔVOUT = –0.1V (Note 2) VOUT = 1.24V, VIN < 1.24V (Note 2) l l l l l l l l l l l l (LT3012E) The l denotes the specifications which apply over the –40°C to 125°C operating temperature range, otherwise specifications are at TJ = 25°C. MIN 1.225 1.2 TYP 4 1.24 1.24 0.1 7 160 250 400 40 3 10 100 30 0.3 1.3 0.8 0.3 0.1 1 65 250 12 25 75 400 100 2 2 1 5 MAX 4.75 1.255 1.28 5 12 25 230 300 340 420 490 620 100 18 UNITS V V V mV mV mV mV mV mV mV mV mV μA mA mA μVRMS nA V V μA μA μA dB mA mA μA ELECTRICAL CHARACTERISTICS PARAMETER Minimum Input Voltage ADJ Pin Voltage (Notes 2, 3) Line Regulation Load Regulation (Note 2) Dropout Voltage VIN = VOUT(NOMINAL) (Notes 4, 5) CONDITIONS ILOAD = 200mA (LT3012H) The l denotes the specifications which apply over the –40°C to 140°C operating temperature range, otherwise specifications are at TJ = 25°C. MIN l l l l l l l l l TYP 4 1.24 1.24 0.1 6 160 250 360 40 3 7 MAX 4.75 1.255 1.28 5 12 30 230 320 340 450 490 630 110 18 UNITS V V V mV mV mV mV mV mV mV mV mV μA mA mA 3012fd VIN = 4V, ILOAD = 1mA 4.75V < VIN < 80V, 1mA < ILOAD < 200mA ΔVIN = 4V to 80V, ILOAD = 1mA (Note 2) VIN = 4.75V, ΔILOAD = 1mA to 200mA VIN = 4.75V, ΔILOAD = 1mA to 200mA ILOAD = 10mA ILOAD = 10mA ILOAD = 50mA ILOAD = 50mA ILOAD = 200mA ILOAD = 200mA 1.225 1.2 GND Pin Current VIN = 4.75V (Notes 4, 6) ILOAD = 0mA ILOAD = 100mA ILOAD = 200mA 3 LT3012 ELECTRICAL CHARACTERISTICS PARAMETER Output Voltage Noise ADJ Pin Bias Current Shutdown Threshold SHDN Pin Current (Note 8) Quiescent Current in Shutdown Ripple Rejection Current Limit Reverse Output Current (Note 9) CONDITIONS COUT = 10μF, ILOAD = 200mA, 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 = 200mA VIN = 7V, VOUT = 0V VIN = 4.75V, ΔVOUT = – 0.1V (Note 2) VOUT = 1.24V, VIN < 1.24V (Note 2) l l l (LT3012H) The l denotes the specifications which apply over the –40°C to 140°C operating temperature range, otherwise specifications are at TJ = 25°C. MIN TYP 100 30 0.3 1.3 0.8 0.3 0.1 1 65 200 12 25 75 400 100 2 2 1 5 MAX UNITS μVRMS nA V V μA μA μA dB mA 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 LT3012 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 LT3012 is tested and specified for these conditions with an external resistor divider (249k bottom, 649k top) for an output voltage of 4.5V. The external resistor divider will add 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 will be equal to (VIN – VDROPOUT). Note 6: GND pin current is tested with VIN = 4.75V and a current source load. This means the device is tested while operating close to its dropout region. This is the worst-case GND pin current. The GND pin current will decrease 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 the GND pin. Note 10: The LT3012E 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. The LT3012H is tested to the LT3012H Electrical Characteristics table at 140°C operating junction temperature. High junction temperatures degrade operating lifetimes. Operating lifetime is derated at junction temperatures greater than 125°C. Note 11: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C (LT3012E) or 140°C (LT3012H) when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. 3012fd 4 LT3012 TYPICAL PERFORMANCE CHARACTERISTICS Typical Dropout Voltage 600 GUARANTEED DROPOUT VOLTAGE (mV) 500 DROPOUT VOLTAGE (mV) 400 300 200 100 0 TJ = 25°C TJ = 125°C 600 500 DROPOUT VOLTAGE (mV) 400 300 200 100 0 0 50 100 150 200 OUTPUT CURRENT (mA) 250 3012 G01 Guaranteed Dropout Voltage = TEST POINTS 600 TJ ≤ 125°C 500 400 300 200 100 Dropout Voltage IL = 250mA IL = 100mA TJ ≤ 25°C IL = 50mA IL = 10mA IL = 1mA 0 50 150 100 200 OUTPUT CURRENT (mA) 250 3012 G02 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G03 Quiescent Current 100 VIN = 6V 90 RL = ∞ I =0 80 L 70 60 50 40 30 20 10 0 –50 –25 0 VSHDN = GND 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G04 ADJ Pin Voltage 1.260 1.255 ADJ PIN VOLTAGE (V) 1.250 1.245 1.240 1.235 1.230 1.225 1.220 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G05 Quiescent Current 80 70 QUIESCENT CURRENT (μA) 60 50 40 30 20 10 VSHDN = GND 0 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 VSHDN = VIN TJ = 25°C RL = ∞ VOUT = 1.24V IL = 1mA QUIESCENT CURRENT (μA) VSHDN = VIN 3012 G06 Quiescent Current 250 TJ = 25°C 225 RL = ∞ VOUT = 1.24V 200 GND PIN CURRENT (mA) 175 150 125 100 75 50 25 0 0 10 20 30 40 50 60 INPUT VOLTAGE (V) 70 80 0 VSHDN = GND VSHDN = VIN 1.2 1.0 0.8 0.6 0.4 0.2 GND Pin Current TJ = 25°C *FOR VOUT = 1.24V GND PIN CURRENT (mA) RL = 49.6Ω IL = 25mA* RL = 124Ω IL = 10mA* 10 9 8 7 6 5 4 3 2 1 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 0 GND Pin Current TJ = 25°C, *FOR VOUT = 1.24V QUIESCENT CURRENT(μA) RL = 4.96Ω IL = 250mA* RL = 12.4Ω IL = 100mA* RL = 1.24k IL = 1mA* RL = 24.8Ω, IL = 50mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 3012 G07 3012 G08 3012 G09 3012fd 5 LT3012 TYPICAL PERFORMANCE CHARACTERISTICS GND Pin Current vs ILOAD 10 VIN = 4.75V 9 TJ = 25°C = 1.24V V 8 OUT 7 6 5 4 3 2 1 0 0 50 100 150 200 LOAD CURRENT (mA) 250 3012 G10 SHDN Pin Threshold 2.0 1.8 SHDN PIN THRESHOLD (V) SHDN PIN CURRENT (μA) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 –50 –25 0 0 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G11 SHDN Pin Current 0.6 TJ = 25°C CURRENT FLOWS 0.5 OUT OF SHDN PIN GND PIN CURRENT (mA) OFF-TO-ON 0.4 0.3 0.2 0.1 ON-TO-OFF 0 0.5 1.0 2.0 1.5 2.5 SHDN PIN VOLTAGE (V) 3.0 3012 G12 SHDN Pin Current 0.6 VIN = 6V VSHDN = 0V 0.5 CURRENT FLOWS OUT OF SHDN PIN 0.4 0.3 0.2 0.1 0 –50 –25 120 100 ADJ Pin Bias Current 1000 900 ADJ PIN BIAS CURRENT (nA) 800 CURRENT LIMIT (mA) 700 600 500 400 300 200 100 Current Limit VOUT = 0V SHDN PIN CURRENT (μA) 80 60 40 20 0 –50 –25 TJ = 25°C TJ = 125°C 0 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G13 0 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G14 0 0 10 20 30 40 50 60 INPUT VOLTAGE (V) 70 80 3012 G15 Current Limit 700 REVERSE OUTPUT CURRENT (μA) 600 CURRENT LIMIT (mA) 500 400 300 200 100 VIN = 7V VOUT = 0V 0 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G16 Reverse Output Current 200 REVERSE OUTPUT CURRENT (μA) TJ = 25°C 180 VIN = 0V VOUT = VADJ 160 140 120 100 CURRENT FLOWS 80 INTO OUTPUT PIN 60 40 20 0 0 1 2 345678 OUTPUT VOLTAGE (V) 9 10 ADJ PIN CLAMP (SEE APPLICATIONS INFORMATION) 120 100 80 60 40 20 Reverse Output Current VIN = 0V VOUT = VADJ = 1.24V 0 –50 –25 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G18 3012 G17 3012fd 6 LT3012 TYPICAL PERFORMANCE CHARACTERISTICS Input Ripple Rejection 92 88 RIPPLE REJECTION (dB) RIPPLE REJECTION (dB) 84 80 76 72 68 64 60 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G19 Input Ripple Rejection 100 90 80 70 60 50 40 30 20 10 0 10 100 1k 10k FREQUENCY (Hz) 100k 1M 3012 G20 Minimum Input Voltage 5.0 4.5 MINIMUM INPUT VOLTAGE (V) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G21 VIN = 4.75V + 50mVRMS RIPPLE ILOAD = 250mA ILOAD = 250mA COUT = 10μF VIN = 4.75V + 0.5VP-P RIPPLE AT f = 120Hz IL = 250mA VOUT = 1.24V COUT = 3.3μF Load Regulation OUTPUT NOISE SPECTRAL DENSITY (μV/√Hz) 0 –2 LOAD REGULATION (mV) –4 –6 –8 –10 –12 –14 –16 –18 –20 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 3012 G22 Output Noise Spectral Density 10 COUT = 3.3μF ILOAD = 250mA ΔIL = 1mA TO 250mA 1 0.1 0.01 10 100 1k 10k FREQUENCY (Hz) 100k 3012 G23 10Hz to 100kHz Output Noise 0.15 OUTPUT VOLTAGE DEVIATION (V) 0.10 0.05 0 –0.05 –0.10 –0.15 300 200 100 0 Transient Response VOUT 100μV/DIV COUT = 10μF IL = 250mA VOUT = 1.24V 1ms/DIV 3012 G24 LOAD CURRENT (mA) VIN = 6V VOUT = 5V CIN = 3.3μF CERAMIC COUT = 3.3μF CERAMIC ΔILOAD = 100mA TO 200mA 0 100 300 200 TIME (μs) 400 500 3012 G25 3012fd 7 LT3012 PIN FUNCTIONS (DFN Package/TSSOP Package) NC (Pins 1, 6, 7, 9, 12)/(Pins 2, 7, 10, 12, 15): No Connect. These pins have no internal connection; connecting NC pins to a copper area for heat dissipation provides a small improvement in thermal performance. OUT (Pins 2, 3)/(Pins 3, 4): Output.The output supplies power to the load. A minimum output capacitor of 3.3μF 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. ADJ (Pin 4)/(Pin 5): Adjust. This is the input to the error amplifier. This pin is internally clamped to ±7V. It has a bias current of 30nA which flows into the pin (see curve of ADJ Pin Bias Current vs Temperature in the Typical Performance Characteristics). The ADJ pin voltage is 1.24V referenced to ground, and the output voltage range is 1.24V to 60V. GND (Pins 5, 13)/(Pins 1, 6, 8, 9, 16, 17): Ground. The exposed backside of the package is an electrical connection for GND. As such, to ensure optimum device operation and thermal performance, the exposed pad must be connected directly to pin 5/pin 6 on the PC board. SHDN (Pin 8)/(Pin 11): Shutdown. The SHDN pin is used to put the LT3012 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 open-collector logic with a pull-up resistor. The pull-up resistor is only required to supply the pull-up current of the open-collector gate, normally several microamperes. If unused, the SHDN pin must be tied to a logic high or to VIN. IN (Pins 10, 11)/(Pins 13,14): 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 1μF to 10μF is sufficient. The LT3012 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 LT3012 will act as if there is a diode in series with its input. There will be no reverse current flow into the LT3012 and no reverse voltage will appear at the load. The device will protect both itself and the load. APPLICATIONS INFORMATION The LT3012 is a 250mA high voltage low dropout regulator with micropower quiescent current and shutdown. The device is capable of supplying 250mA at a dropout voltage of 400mV. The low operating quiescent current (40μA) drops to 1μA in shutdown. In addition to the low quiescent current, the LT3012 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 LT3012 acts like it has a diode in series with its output and prevents reverse current flow. Adjustable Operation The LT3012 has an output voltage range of 1.24V to 60V. The output voltage is set by the ratio of two external resistors as shown in Figure 1. The device servos the output to maintain the voltage at the adjust pin at 1.24V referenced to ground. The current in R1 is then equal to 1.24V/R1 and the current in R2 is the current in R1 plus the ADJ pin bias current. The ADJ pin bias current, 30nA 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 250k 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. 3012fd 8 LT3012 APPLICATIONS INFORMATION IN VIN OUT LT3012 ADJ GND R1 3012 F01 R2 + VOUT improved transient response for larger load current changes. Bypass capacitors, used to decouple individual components powered by the LT3012, will increase the effective output capacitor value. 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 specified with EIA temperature characteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high capacitances in a small package, but they tend to have strong voltage and temperature coefficients as shown in Figures 2 and 3. When used with a 5V regulator, a 16V 10μF Y5V capacitor can exhibit an effective value as low as 1μF to 2μF for the DC bias voltage applied and 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. Care still must be exercised when using X5R and X7R capacitors; the X5R and X7R codes only specify operating temperature range and maximum capacitance change over temperature. Capacitance change due to DC bias with X5R and X7R capacitors is better than Y5V and Z5U capacitors, but can still be significant enough to drop capacitor values below appropriate levels. Capacitor DC bias characteristics tend to improve as component case size increases, but expected capacitance at operating voltage should be verified. 40 20 CHANGE IN VALUE (%) 0 X5R –20 –40 –60 –80 Y5V VOUT = 1.24V 1 + R2 + (IADJ)(R2) R1 VADJ = 1.24V IADJ = 30nA AT 25°C OUTPUT RANGE = 1.24V TO 60V Figure 1. Adjustable Operation The adjustable 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 1.24V. Specifications for output voltages greater than 1.24V will be proportional to the ratio of the desired output voltage to 1.24V; (VOUT /1.24V). For example, load regulation for an output current change of 1mA to 250mA is –7mV typical at VOUT = 1.24V. At VOUT = 12V, load regulation is: (12V/1.24V) • (–7mV) = –68mV Output Capacitance and Transient Response The LT3012 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 3.3μF with an ESR of 3Ω or less is recommended to prevent oscillations. The LT3012 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 20 0 CHANGE IN VALUE (%) X5R –20 –40 –60 Y5V –80 –100 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10μF 0 2 4 8 6 10 12 DC BIAS VOLTAGE (V) 14 16 3012 F02 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10μF –100 50 25 75 –50 –25 0 TEMPERATURE (°C) 100 125 3012 F03 Figure 2. Ceramic Capacitor DC Bias Characteristics Figure 3. Ceramic Capacitor Temperature Characteristics 3012fd 9 LT3012 APPLICATIONS INFORMATION 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, 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. Current Limit and Safe Operating Area Protection Like many IC power regulators, the LT3012 has safe operating area protection. The safe operating area protection decreases the current limit as the input voltage increases and keeps the power transistor in a safe operating region. The protection is designed to provide some output current at all values of input voltage up to the device breakdown (see curve of Current Limit vs Input Voltage in the Typical Performance Characteristics). The LT3012 is limited for operating conditions by maximum junction temperature. While 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. Device specifications will not apply for all possible combinations of input voltage and output current. Operating the LT3012 beyond the maximum junction temperature rating may impair the life of the device. Thermal Considerations The power handling capability of the device will be limited by the maximum rated junction temperature of (125°C for LT3012E, or 140°C for LT3012HFE). 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. The LT3012 has internal thermal limiting designed to protect the device during overload conditions. For continuous normal conditions the maximum junction temperature rating of 125°C (E-Grade) or 140°C (H-Grade)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 tables list 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. DFN Measured Thermal Resistance COPPER AREA TOPSIDE 2500 sq mm 1000 sq mm 225 sq mm 100 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 Table 2. TSSOP Measured Thermal Resistance COPPER AREA TOPSIDE 2500 sq mm 1000 sq mm 225 sq mm 100 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 The thermal resistance junction-to-case (θJC), measured at the exposed pad on the back of the die, is 16°C/W. 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). 3012fd 10 LT3012 APPLICATIONS INFORMATION 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 50mA, 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) = 50mA VIN(MAX) = 30V IGND at (IOUT = 50mA, VIN = 30V) = 1mA So: P = 50mA • (30V – 5V) + (1mA • 30V) = 1.28W The thermal resistance 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: 1.31W • 50°C/W = 65.5°C 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 + 65.5°C = 115.5°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 50mA 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) + (200μA • 48V) = 0.23W P2(48V in, 50mA load) = 50mA • (48V – 5V) + (1mA • 48V) = 2.20W 3012fd P3(72V in, 5mA load) = 5mA • (72V – 5V) + (200μA • 72V) = 0.35W P4(72V in, 50mA load) = 50mA • (72V – 5V) + (1mA • 72V) = 3.42W 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%(0.23W) + 19%(2.20W) + 4%(0.35W) + 1%(3.42W) = 0.64W 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 26°C to 38°C. High Temperature Operation Care must be taken when designing LT3012 applications to operate at high ambient temperatures. The LT3012 works at elevated temperatures but erratic operation can occur due to unforeseen variations in external components. Some tantalum capacitors are available for high temperature operation, but ESR is often several ohms; capacitor ESR above 3Ω is unsuitable for use with the LT3012. Ceramic capacitor manufacturers (Murata, AVX, TDK, and Vishay Vitramon at this writing) now offer ceramic capacitors that are rated to 150°C using an X8R dielectric. Device instability will occur if output capacitor value and ESR are outside design limits at elevated temperature and operating DC voltage bias (see information on capacitor characteristics under Output Capacitance and Transient Response). Check each passive component for absolute value and voltage ratings over the operating temperature range. Leakages in capacitors or from solder flux left after insuficient board cleaning adversely affects low quiescent current operation. The output voltage resistor divider should use a maximum bottom resistor value of 124k to compensate for high temperature leakage, setting divider current to 10μA. Consider junction temperature increase due to power dissipation in both the junction and nearby components to ensure maximum specifications are not violated for the device or external components. 11 LT3012 APPLICATIONS INFORMATION Protection Features The LT3012 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. Like many IC power regulators, the LT3012 has safe operating area protection. The safe area protection decreases the current limit as input voltage increases and keeps the power transistor inside a safe operating region for all values of input voltage. The protection is designed to provide some output current at all values of input voltage up to the device breakdown. The SOA protection circuitry for the LT3012 uses a current generated when the input voltage exceeds 25V to decrease current limit. This current shows up as additional quiescent current for input voltages above 25V. This increase in quiescent current occurs both in normal operation and in shutdown (see curve of Quiescent Current in the Typical Performance Characteristics). 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 (LT3012E) or 140°C (LT3012HFE). The input of the device will withstand reverse voltages of 80V. 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 of the device 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 a unregulated high voltage. Pulling the ADJ pin above the reference voltage will turn off all output current. 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 1.24V 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 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. 200 REVERSE OUTPUT CURRENT (μA) TJ = 25°C 180 VIN = 0V VOUT = VADJ 160 140 120 100 CURRENT FLOWS 80 INTO OUTPUT PIN 60 40 20 0 0 1 2 345678 OUTPUT VOLTAGE (V) 9 10 ADJ PIN CLAMP (SEE ABOVE) 3012 F04 Figure 4. Reverse Output Current When the IN pin of the LT3012 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 LT3012 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. 3012fd 12 LT3012 TYPICAL APPLICATIONS 5V Buck Converter with Low Current Keep Alive Backup D2 D1N914 6 VIN 5.5V* TO 60V 4 C3 4.7μF 100V CERAMIC BOOST 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 L1† 15μH D1 10MQ060N VOUT 5V 1A/250mA + C1 100μF 10V SOLID TANTALUM 1, 8, 9, 16 11 14 OPERATING CURRENT LOW HIGH 11 IN LT3012 SHDN GND 1 OUT ADJ 3 5 750k * 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 3012 TA03 249k Buck Converter Efficiency vs Load Current 100 VOUT = 5V L = 68μH VIN = 10V 90 EFFICIENCY (%) VIN = 42V 80 70 60 50 0 0.25 0.75 1.00 0.50 LOAD CURRENT (A) 1.25 3012 TA04 3012fd 13 LT3012 TYPICAL APPLICATIONS LT3012 Automotive Application VIN 12V (LATER 42V) + 1μF IN NO PROTECTION DIODE NEEDED! LT3012 SHDN GND OUT 750k ADJ 249k 3.3μF LOAD: CLOCK, SECURITY SYSTEM ETC OFF ON LT3012 Telecom Application VIN 48V (72V TRANSIENT) 1μF IN LT3012 SHDN GND OUT 750k NO PROTECTION DIODE NEEDED! 249k 3012 TA05 + 3.3μF LOAD: SYSTEM MONITOR ETC ADJ – BACKUP BATTERY OFF ON Constant Brightness for Indicator LED over Wide Input Voltage Range RETURN 1μF OFF ON IN OUT LT3012 SHDN GND –48V ILED = 1.24V/RSET –48V CAN VARY FROM –4V TO –80V ADJ RSET 3012 TA06 3.3μF 3012fd 14 LT3012 PACKAGE DESCRIPTION DE Package 12-Lead Plastic DFN (4mm × 3mm) (Reference LTC DWG # 05-08-1695) 4.00 ± 0.10 (2 SIDES) 0.70 ± 0.05 3.30 ± 0.05 1.70 ± 0.05 PIN 1 TOP MARK PACKAGE (NOTE 6) OUTLINE 0.200 REF R = 0.05 TYP 3.00 ± 0.10 (2 SIDES) 3.30 ± 0.10 1.70 ± 0.10 PIN 1 NOTCH R = 0.20 OR 0.35 × 45° CHAMFER (UE12/DE12) DFN 0806 REV D 7 R = 0.115 TYP 0.40 ± 0.10 12 3.60 ± 0.05 2.20 ± 0.05 0.25 ± 0.05 2.50 REF 0.75 ± 0.05 6 0.25 ± 0.05 2.50 REF 1 0.50 BSC 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING PROPOSED TO BE A VARIATION OF VERSION (WGED) IN JEDEC PACKAGE OUTLINE M0-229 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 THE TOP AND BOTTOM OF PACKAGE FE Package 16-Lead Plastic TSSOP (4.4mm) (Reference LTC DWG # 05-08-1663) Exposed Pad Variation BB 3.58 (.141) 4.90 – 5.10* (.193 – .201) 3.58 (.141) 16 1514 13 12 1110 9 6.60 ± 0.10 4.50 ± 0.10 SEE NOTE 4 2.94 (.116) 0.45 ± 0.05 1.05 ± 0.10 0.65 BSC 2.94 6.40 (.116) (.252) BSC RECOMMENDED SOLDER PAD LAYOUT 12345678 1.10 (.0433) MAX 0° – 8° 4.30 – 4.50* (.169 – .177) 0.25 REF 0.09 – 0.20 (.0035 – .0079) 0.50 – 0.75 (.020 – .030) 0.65 (.0256) BSC NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) 3. DRAWING NOT TO SCALE 0.195 – 0.30 (.0077 – .0118) TYP 0.05 – 0.15 (.002 – .006) FE16 (BB) TSSOP 0204 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE 3012fd 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 LT3012 RELATED PARTS PART NUMBER LT1020 LT1120/LT1120A DESCRIPTION COMMENTS 125mA, Micropower Regulator and Comparator VIN: 4.5V to 36V, VOUT(MIN) = 2.5V, VDO = 0.4V, IQ = 40μA, ISD = 40μA, Comparator and Reference, Class B Outputs, S16, PDIP14 Packages 125mA, Micropower Regulator and Comparator VIN: 4.5V to 36V, VOUT(MIN) = 2.5V, VDO = 0.4V, IQ = 40μA, ISD = 10μA, Comparator and Reference, Logic Shutdown, Ref Sources and Sinks 2/4mA, S8, N8 Packages 150mA, Micropower, LDO 700mA, Micropower, LDO 60V, 440mA (IOUT), 100kHz, High Efficiency Step-Down DC/DC Converter 100mA, Low Noise Micropower, LDO 150mA, Low Noise Micropower, LDO 500mA, Low Noise Micropower, LDO 3A, Low Noise, Fast Transient Response, LDO VIN: 4.2V to 30/36V, VOUT(MIN) = 3.75V, VDO = 0.42V, IQ = 30μA, ISD = 16μA, Reverse Battery Protection, SOT-223, S8, Z Packages VIN: 4.2V to 30V, VOUT(MIN) = 3.75V, VDO = 0.4V, IQ = 50μA, ISD = 16μA, DD, S0T-223, S8,TO220-5, TSSOP20 Packages VIN: 7.4V to 60V, VOUT(MIN) = 1.24V, IQ = 3.2mA, ISD = 2.5μA, S8 Package VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.3V, IQ = 20μA, ISD =