LT1083/84/85 Fixed 3A, 5A, 7.5A Low Dropout Positive Fixed Regulators U DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ Three-Terminal 3.3V, 3.6V, 5V and 12V Output Current of 3A, 5A or 7.5A Operates Down to 1V Dropout Guaranteed Dropout Voltage at Multiple Current Levels Line Regulation: 0.015% Load Regulation: 0.1% 100% Thermal Limit Functional Test Adjustable Versions Available U APPLICATIONS ■ ■ ■ ■ High Efficiency Linear Regulators Post Regulators for Switching Supplies Constant Current Regulators Battery Chargers The LT1083 series of positive adjustable regulators are designed to provide 3A, 5A and 7.5A with higher efficiency than currently available devices. All internal circuitry is designed to operate down to 1V input to output differential and the dropout voltage is fully specified as a function of load current. Dropout is guaranteed at a maximum of 1.5V at maximum output current, decreasing at lower load currents. On-chip trimming adjusts the output voltage to 1%. Current limit is also trimmed, minimizing the stress on both the regulator and power source circuitry under overload conditions. The 1083 series devices are pin compatible with older three-terminal regulators. A 10µF output capacitor is required on these new devices; however, this is usually included in most regulator designs. DEVICE OUTPUT CURRENT* LT1083 LT1084 LT1085 7.5 Amps 5.0 Amps 3.0 Amps Unlike PNP regulators, where up to 10% of the output current is wasted as quiescent current, the LT1083 quiescent current flows into the load, increasing efficiency. *For a 1.5A low dropout regulator see the LT1086 data sheet. U TYPICAL APPLICATION 5V, 7.5A Regulator 5V AT 7.5A LT1083-5 + + 10µF *REQUIRED FOR STABILITY 22µF* TANTALUM LT1083/4/5 TA01 INPUT/OUTPUT VOLTAGE DIFFERENTIAL (V) VIN ≥ 6.5V Dropout Voltage vs Output Current 2 1 0 0 IFULL LOAD/2 OUTPUT CURRENT (A) IFULL LOAD 1083/4/5 TA02 1 LT1083/84/85 Fixed U W W W ABSOLUTE MAXIMUM RATINGS Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C Note 1: Although the devices maximum operating voltage is limited, (20V for a 3V, 5V device, and 25V for a 12V device) the devices are guaranteed to withstand transient input voltages up to 30V. For input voltages greater than the maximum operating input voltage some degradation of specifications will occur. For input/output voltage differentials greater than 15V, a minimum external load of 5mA is required to maintain regulation. UU U Power Dissipation............................... Internally Limited Input Voltage (Note 1) ............................................. 30V Operating Input Voltage 3.3V, 3.6V Devices ............................................ 20V 5V Devices ........................................................ 20V 12V Devices ...................................................... 25V Operating Junction Temperature Range “C” Grades Control Section ............................... 0°C to 125°C Power Transistor ............................. 0°C to 150°C “M” Grades Control Section ........................... –55°C to 150°C Power Transistor ......................... –55°C to 200°C PRECONDITIONING 100% Thermal Limit Functional Test. W U U PACKAGE/ORDER INFORMATION CASE IS OUTPUT VIN ORDER PART NUMBER LT1083CK-5 LT1083CK-12 LT1083MK-5 LT1083MK-12 LT1084CK-5 LT1084CK-12 2 1 GND K PACKAGE 2-LEAD TO-3 METAL CAN LT1084MK-5 LT1084MK-12 LT1085CK-5 LT1085CK-12 LT1085MK-5 LT1085MK-12 TAB IS OUTPUT 3 VIN 2 VOUT 1 GND LT1083CP-5 LT1083CP-12 LT1084CP-5 LT1084CP-12 P PACKAGE 3-LEAD TO-3P PLASTIC θJA = 45°C/W θJA = 35°C/W FRONT VIEW TAB IS OUTPUT ORDER PART NUMBER FRONT VIEW 3 VIN 2 VOUT 1 GND T PACKAGE 3-LEAD PLASTIC TO-220 θJA = 50°C/W LT1084CT-3.3 LT1084CT-5 LT1084CT-12 LT1085CT-3.3 LT1085CT-3.6 LT1085CT-5 LT1085CT-12 FRONT VIEW TAB IS OUTPUT 3 VIN 2 VOUT 1 GND LT1085CM-3.3 LT1085CM-3.6 M PACKAGE 3-LEAD PLASTIC DD θJA = 30°C/W* * WITH PACKAGE SOLDERED TO 0.52IN2 COPPER AREA OVER BACKSIDE GROUND PLANE OR INTERNAL POWER PLANE. θJA CAN VARY FROM 20°C/W TO > 40°C/W DEPENDING ON MOUNTING TECHNIQUE. Consult factory for Industrial grade parts. ELECTRICAL CHARACTERISTICS PARAMETER Output Voltage CONDITIONS LT1084-3.3 LT1085-3.3 LT1085-3.6 2 IOUT = 0mA, TJ = 25°C, VIN = 8V (K Package Only) 0 ≤ IOUT ≤ 5A, 4.8V ≤ VIN ≤ 15V (Note 8) VIN = 5V, IOUT = 0mA, TJ = 25°C (K Package Only) 4.8V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ 3A (Note 8) VIN = 5V, IOUT = 0mA, TJ = 25°C (K Package Only) 5V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ 3A (Note 8) 5V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ 3A, TJ ≥ 0°C (Note 8) ● ● ● MIN 3.270 3.235 3.270 3.235 3.564 3.500 3.528 TYP 3.300 3.300 3.300 3.300 3.600 MAX 3.330 3.365 3.330 3.365 3.636 3.672 3.672 UNITS V V V V V V V LT1083/84/85 Fixed ELECTRICAL CHARACTERISTICS PARAMETER Output Voltage CONDITIONS LT1085-3.6 LT1083/4/5-5 LT1083/4/5-12 Line Regulation LT1084-3.3 5V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ 2.5A (Note 8) VIN = 4.75V, IOUT = 3A, TJ ≥ 0°C VIN = 4.75V, IOUT = 2.5A, TJ ≥ 0°C VIN = 4.75V, IOUT = 1.5A, TJ > 0°C IOUT = 0mA, TJ = 25°C, VIN = 8V (K Package Only) 0 ≤ IOUT ≤ IFULLOAD, 6.5V ≤ VIN ≤ 20V (Notes 3, 5, 6, 8) IOUT = 0mA, TJ = 25°C, VIN = 15V (K Package Only) 0 ≤ IOUT ≤ IFULLOAD, 13.5V ≤ VIN ≤ 25V (Notes 3, 5, 6, 8) IOUT = 0mA, TJ = 25°C, 4.8V ≤ VIN ≤ 15V ● MIN 3.528 3.350 3.450 3.528 4.950 4.900 11.880 11.760 ● LT1085-3.3 4.8V ≤ VIN ≤ 15V, IOUT = 0mA, TJ= 25°C ● LT1085-3.6 4.8V ≤ VIN ≤ 15V, IOUT = 0mA, TJ= 25°C ● LT1083/4/5-5 IOUT = 0mA, TJ = 25°C, 6.5V ≤ VIN ≤ 20V (Notes 1, 2) ● LT1083/4/5-12 IOUT = 0mA, TJ = 25°C, 13.5V ≤ VIN ≤ 25V (Notes 1, 2) ● Load Regulation LT1084-3.3 VIN = 5V, 0 ≤ IOUT ≤ 5A, TJ = 25°C ● LT1085-3.3 VIN = 5V, 0 ≤ IOUT ≤ 3A, TJ = 25°C ● LT1085-3.6 VIN = 5.25V, 0 ≤ IOUT ≤ 3A, TJ = 25°C ● LT1083/4/5-5 VIN = 8V, 0 ≤ IOUT ≤ IFULLLOAD, TJ = 25°C (Notes 1, 2, 3, 5) ● LT1083/4/5-12 Dropout Voltage Current Limit Quiescient Current Thermal Regulation Ripple Rejection VIN = 15V, 0 ≤ IOUT ≤ IFULLLOAD, TJ = 25°C (Notes 1, 2, 3, 5) LT1084/5-3.3 ∆VOUT = 33mV, IOUT = IFULL LOAD (Notes 4, 5) LT1085-3.6 ∆VOUT = 36mV, IOUT = IFULL LOAD (Notes 4, 5) LT1083/4/5-5 ∆VOUT = 50mV, IOUT = IFULL LOAD (Notes 4, 5) LT1083/4/5-12 ∆VOUT = 120mV, IOUT = IFULL LOAD (Notes 4, 5) LT1083-5 VIN = 10V LT1083-12 VIN = 17V LT1084-3.3 VIN = 8V LT1084-5 VIN = 10V LT1084-12 VIN = 17V LT1085-3.3/3.6 VIN = 8V LT1085-5 VIN = 10V LT1085-12 VIN = 17V LT1084-3.3 VIN = 18V LT1085-3.3 VIN = 18V LT1085-3.6 VIN = 18V LT1083/4/5-5 VIN ≤ 20V LT1083/4/5-12 VIN ≤ 25V LT1083-5/12 TA = 25°C, 30ms pulse LT1084-3.3/5/12 LT1085-3.3/3.6/5/12 f = 120Hz, COUT = 25µF Tantalum, IOUT = IFULLLOAD LT1084-3.3 f = 120Hz, COUT = 25µF Tantalum, IOUT = 5A, VIN = 6.3V ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 8.0 8.0 5.5 5.5 5.5 3.2 3.2 3.2 ● 60 TYP MAX 3.672 3.672 3.672 3.672 5.050 5.100 12.120 12.240 6 6 6 6 6 6 10 10 25 25 15 20 15 20 15 20 20 35 36 72 1.5 1.5 1.5 1.5 5.000 5.000 12.000 12.000 0.5 1.0 0.5 1.0 0.5 1.0 0.5 1.0 1.0 2.0 3 7 3 7 3 7 5 10 12 24 1.3 1.3 1.3 1.3 9.5 9.5 6.5 6.5 6.5 4.0 4.0 4.0 5.0 10.0 5.0 10.0 5.0 10.0 5.0 10.0 5.0 10.0 0.002 0.010 0.003 0.015 0.004 0.020 72 UNITS V V V V V V V V mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV V V V V A A A A A A A A mA mA mA mA mA %/W %/W %/W dB 3 LT1083/84/85 Fixed ELECTRICAL CHARACTERISTICS PARAMETER Ripple Rejection CONDITIONS LT1085-3.3 LT1085-3.6 LT1083/4/5-5 LT1083/4/5-12 Temperature Stability Long Term Stability RMS Output Noise (% of VOUT) Thermal Resistance Junctrion-to-Case ● ● ● ● ● f = 120Hz, COUT = 25µF Tantalum, VIN = 6.3V, IOUT = 3A f = 120Hz, COUT = 25µF Tantalum, VIN = 6.6V, IOUT = 3A VIN = 8V (Note 5) VIN = 15V (Note 5) MIN 60 60 60 54 TA = 125°C, 1000 Hrs. TA = 25°C, 10Hz = ≤ f ≤ 10kHz Control Circuitry/Power Transistor (See Applications Information) LT1083 K Package P Package LT1084 K Package P Package T Package LT1085 K Package T Package DD Package The ● denotes the specifications which apply over the full operating temperature range. Note 1: See thermal regulation specifications for changes in output voltage due to heating effects. Load and line regulation are measured at a constant junction temperature by low duty cycle pulse testing. Note 2: Line and load regulation are guaranteed up to the maximum power dissipation (60W for the LT1083, 45W for the LT1084 (K, P), 30W for the LT1084 (T) and 30W for the LT1085). Power dissipation is determined by the input/output differential and the output current. Guaranteed maximum power dissipation will not be available over the full input/output range. Note 3: IFULL LOAD is defined in the current limit curves. The IFULLLOAD curve is defined as the minimum value of current limit as a function of TYP 72 72 68 60 0.5 0.03 MAX UNITS dB dB dB dB % % 1.0 0.003 % 0.6/1.6 0.5/1.6 0.75/2.3 0.65/2.3 0.65/2.7 0.9/3.0 0.7/3.0 0.7/3.0 °C/W °C/W °C/W °C/W °C/W °C/W °C/W °C/W input to output voltage. Note that the 60W power dissipation for the LT1083 (45W for the LT1084 (K, P), 30W for the LT1084 (T), 30W for the LT1085) is only achievable over a limited range of input to output voltage. Note 4: Dropout voltage is specified over the full output current range of the device. Test points and limits are shown on the Dropout Voltage curve. Note 5: For LT1083 IFULL LOAD is 5A for – 55°C ≤ TJ ≤ – 40°C and 7.5A for TJ ≥ – 40°C. Note 6: 1.7V ≤ (VIN – VOUT) ≤ 25V for LT1084 at – 55°C ≤ TJ ≤ – 40°C. Note 7: Dropout voltage 1.7V maximum for LT1084 at – 55 ≤ TJ ≤ – 40°C. Note 8: Full load current is not available at all input-output voltages. See Notes 2,3,5. U W TYPICAL PERFORMANCE CHARACTERISTICS LT1083 Short-Circuit Current INDICATES GUARANTEED TEST POINT TJ = 150°C TJ = 25°C TJ = –55°C 0 1 2 3 4 5 6 7 8 OUTPUT CURRENT (A) 9 10 LT1083/4/5 FIXED G01 4 OUTPUT VOLTAGE DEVIATION (%) 0°C ≤ TJ ≤ 125°C 0 0.10 ∆I = 7.5A –40°C ≤ TJ ≤ 150°C 1 LT1083 Load Regulation 12 SHORT-CIRCUIT CURRENT (A) MINIMUM INPUT/OUTPUT DIFFERENTIAL (V) LT1083 Dropout Voltage 2 25°C 10 150°C 8 6 –55°C 4 IFULL LOAD GUARANTEED 2 0 0 20 30 15 25 5 10 INPUT/OUTPUT DIFFERENTIAL (V) 35 LT1083/4/5 FIXED G02 0.05 0 –0.05 –0.10 –0.15 –0.20 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) LT1083/4/5 FIXED G03 LT1083/84/85 Fixed U W TYPICAL PERFORMANCE CHARACTERISTICS LT1084 Short Circuit Current 2 INDICATES GUARANTEED TEST POINT ∆I = 5A 1 TJ = –55°C TJ = 25°C 8 7 150°C 25°C 6 5 4 –55°C 3 2 IFULL LOAD GUARANTEED 1 1 3 4 2 OUTPUT CURRENT (A) 0 6 5 20 15 10 25 30 5 INPUT/OUTPUT DIFFERENTIAL (V) 0.05 0 –0.05 –0.10 –0.15 –0.20 –50 –25 0 0 35 LT1085 Dropout Voltage LT1085 Load Regulation 6 0.10 INDICATES GUARANTEED TEST POINT –55°C ≤ TJ ≤ 150°C TJ = –55°C TJ = 25°C TJ = 150°C 5 25°C 4 150°C 3 –55°C 2 IFULL LOAD GUARANTEED 1 0 0 0 4 20 30 15 25 5 10 INPUT/OUTPUT DIFFERENTIAL (V) VRIPPLE ≤ 0.5VP-P 60 (VIN – VOUT) ≥ 3V –0.10 –0.15 –0.20 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) LT1083/4/5 FIXED G09 Temperature Stability 2.0 100 90 80 (VIN – VOUT) ≥ VDROPOUT 40 30 20 IOUT = IFULL LOAD fR = 120Hz VRIPPLE ≤ 3VP-P 70 fR = 20kHz VRIPPLE ≤ 0.5VP-P 60 50 40 30 20 10 0 10 –0.05 LT1083/4/5-5 Ripple Rejection vs Current RIPPLE REJECTION (dB) VRIPPLE ≤ 3VP-P 70 0 LT1083/4/5 FIXED G08 LT1083/4/5-5 Ripple Rejection 80 35 0.05 OUTPUT VOLTAGE CHANGE (%) 2 3 1 OUTPUT CURRENT (A) LT1083/4/5 FIXED G07 50 OUTPUT VOLTAGE DEVIATION (%) SHORT-CIRCUIT CURRENT (A) ∆I = 3A 0°C ≤ TJ ≤ 125°C 0 25 50 75 100 125 150 TEMPERATURE (°C) LT1083/4/5 FIXED G06 LT1085 Short-Circuit Current 2 1 0 LT1083/4/5 FIXED G05 LT1083/4/5 FIXEDG04 MINIMUM INPUT/OUTPUT DIFFERENTIAL (V) OUTPUT VOLTAGE DEVIATION (%) 0°C ≤ TJ ≤ 125°C TJ = 150°C 0.10 9 –55°C ≤ TJ ≤ 150°C 0 RIPPLE REJECTION (dB) LT1084 Load Regulation 10 SHORT-CIRCUIT CURRENT (A) MINIMUN INPUT/OUTPUT DIFFERENTIAL (V) LT1084 Dropout Voltage 1.0 0 –1.0 10 100 1k 10k FREQUENCY (Hz) 100k 1083/4/5 FIXED G10 0 0 0.8 0.2 0.6 0.4 OUTPUT CURRENT (0 TO IFULL LOAD) 1.0 1083/4/5 FIXED G11 –2.0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) LT1183/4/5 FIXED G12 5 LT1083/84/85 Fixed U W TYPICAL PERFORMANCE CHARACTERISTICS LT1083/4/5-12 Ripple Rejection vs Current LT1083/4/5-12 Ripple Rejection 80 VRIPPLE ≤ 3VP-P VRIPPLE ≤ 0.5VP-P 70 LT1083 Maximum Power Dissipation* 100 100 90 90 80 (VIN – VOUT) ≥ 3V 50 40 30 (VIN – VOUT) ≥ VDROPOUT 20 IOUT = IFULL LOAD 10 0 10 100 1k 10k FREQUENCY (Hz) 100k fR = 120Hz VRIPPLE ≤ 3VP-P 70 70 POWER (W) 60 RIPPLE REJECTION (dB) RIPPLE REJECTION (dB) 80 60 fR = 20kHz VRIPPLE ≤ 0.5VP-P 50 40 50 40 30 30 20 20 10 10 0 0 0 0.8 0.2 0.6 0.4 OUTPUT CURRENT (0 TO IFULL LOAD) 1083/4/5 FIXED G13 1.0 1083/4/5 FIXED G14 LT1083MK 60 LT1083CP LT1083CK 50 60 70 80 90 100 110 120 130 140 150 CASE TEMPERATURE (°C) * AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE LT1083/4/5 FIXED G15 LT1085 Maximum Power Dissipation* LT1084 Maximum Power Dissipation* 60 50 50 40 LT1084MK 30 LT1084CT LT1084CP 20 10 POWER (W) POWER (W) 40 30 LT1085MK 20 LT1085CT 10 LT1084CK LT1085CK 0 0 6 50 60 70 80 90 100 110 120 130 140 150 CASE TEMPERATURE (°C) * AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE 50 60 70 80 90 100 110 120 130 140 150 CASE TEMPERATURE (°C) * AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE LT1083/4/5 FIXED G16 LT1083/4/5 FIXED G17 LT1083/84/85 Fixed W BLOCK DIAGRAM VIN + – THERMAL LIMIT GND LT1083/4/5 BD U W U U APPLICATIONS INFORMATION The LT1083 family of three-terminal regulators are easy to use and have all the protection features that are expected in high performance voltage regulators. They are short circuit protected, have safe area protection as well as thermal shutdown to turn off the regulator should the temperature exceed about 165°C. These regulators offer lower dropout voltage and more precise reference tolerance. Further, the reference stability with temperature is improved over older types of regulators. The only circuit difference between using the LT1083 family and older regulators is that they require an output capacitor for stability. Stability The circuit design used in the LT1083 family requires the use of an output capacitor as part of the device frequency compensation. For all operating conditions, the addition of 150µF aluminum electrolytic or a 22µF solid tantalum on the output will ensure stability. Normally capacitors much smaller than this can be used with the LT1083. Many different types of capacitors with widely varying charac- teristics are available. These capacitors differ in capacitor tolerance (sometimes ranging up to ±100%), equivalent series resistance, and capacitance temperature coefficient. The 150µF or 22µF values given will ensure stability. Normally, capacitor values on the order of 100µF are used in the output of many regulators to ensure good transient response with heavy load current changes. Output capacitance can be increased without limit and larger values of output capacitance further improve stability and transient response of the LT1083 regulators. Another possible stability problem that can occur in monolithic IC regulators is current limit oscillations. These can occur because in current limit the safe area protection exhibits a negative impedance. The safe area protection decreases the current limit as the input-to-output voltage increases.That is the equivalent of having a negitive resistance since increasing voltage causes current to decrease. Negitive resistance during current limit is not unique to the LT1083 series and has been present on all power IC regulators. The value of negative resistance is a function of how fast the current limit is folded back as input-to- 7 LT1083/84/85 Fixed U W U U APPLICATIONS INFORMATION output voltage increases. This negative resistance can react with capacitors or inductors on the input to cause oscillations during current limiting. Depending on the value of series resistance, the overall circuitry may end up unstable. Since this is a system problem, it is not necessarily easy to solve; however it does not cause any problems with the IC regulator and can usually be ignored. voltage is rising, the input-to-output voltage differential remains small allowing the regulator to supply large output currents. With high input voltage a problem can occur wherein removal of an output short will not allow the output voltage to recover. Older regulators such as the 7800 series, also exhibited this phenomenon so it is not unique to the LT1083. Protection Diodes The problem occurs with a heavy output load when the input voltage is high and the output voltage is low, such as immediately after a removal of a short. The load line for such a load may intersect the output current curve at two points. If this happens there are two stable output operating points for the regulator. With this double intersection the power supply may need to be cycled down to zero and brought up again to make the output recover. In normal operation the LT1083 family does not need any protection diodes, The internal diode between the input and the output pins of the LT1083 family can handle microsecond surge currents of 50A to 100A. Even with large output capacitances it is very difficult to get those values of surge current in normal operation. Only with high value output capacitors, such as 1000µF to 5000µF and with the input pin instantaneously shorted to ground, can damage occur. A crowbar circuit at the input of the LT1083 can generate those kinds of currents and a diode from output-to-input is then recommended. Normal power supply cycling or even plugging and unplugging in the system will not generate currents large enough to do any damage. D1 1N4002 (OPTIONAL) Ripple Rejection In applications that require improved ripple rejection the LT1083 series adjustable regulators should be used. With LT1083 series adjustable regulators the addition of a bypass capacitor from the adjust pin to ground will reduce output ripple by the ratio of VOUT/1.25V. See LT1083 series adjustable regulator data sheet. Load Regulation VIN IN LT1083 ADJ VOUT OUT + COUT 150µF LT1083/4/5 AI01 Overload Recovery Like any of the IC power regulators, the LT1083 has safe area protection. The safe area protection decreases the current limit as input-to-output voltage increases and keeps the power transistor inside a safe operating region for all values of input-to-output voltage. The LT1083 protection is designed to provide some output current at all values of input-to-output voltage up to the device breakdown. When power is first turned on, as the input voltage rises, the output follows the input, allowing the regulator to start up into very heavy loads. During the start-up, as the input 8 Because the LT1083 is a three-terminal device, it is not possible to provide true remote load sensing. Load regulation will not be limited by the resistance of the wire connecting the regulator to the load. The data sheet specification for the load regulation is measured at the bottom of the package. Negative side sensing is a true Kelvin connection, with the ground pin of the device returned to the negative side of the load. Thermal Considerations The LT1083 series of regulators have internal power and thermal limiting circuitry designed to protect the device under overload conditions. For continuous normal load conditions however, maximum junction temperature ratings must not be exceeded. It is important to give careful consideration to all sources of thermal resistance from junction to ambient. This includes junction-to-case, caseto-heat sink interface, and heat sink resistance itself. New LT1083/84/85 Fixed U U W U APPLICATIONS INFORMATION thermal resistance specifications have been developed to more accurately reflect device temperature and ensure safe operating temperatures. The data section for these new regulators provides a separate thermal resistance and maximum junction temperature for both the Control Section and the Power Section. Previous regulators, with a single junction-to-case thermal resistance specification, used an average of the two values provided here and therefore could allow excessive junction temperatures under certain conditions of ambient temperature and heat sink resistance. To avoid this possibility, calculations should be made for both sections to ensure that both thermal limits are met. For example, using a LT1083-5CK (TO-3, Commercial) and assuming: VIN(max continuous) = 9V, VOUT = 5V, IOUT = 6A, TA = 75°C θHEAT SINK = 1°C/W, θCASE-TO-HEAT SINK = 0.2°C/W for K package with thermal compound. Power dissipation under these conditions is equal to: PD = (VIN – VOUT) (IOUT) = 24W Junction temperature will be equal to: TJ = TA + PD (θHEAT SINK + θCASE-TO-HEAT SINK + θJC) For the Control Section: TJ = 75°C + 24W (1°C/W + 0.2°C/W + 0.6°C/W) = 118°C 118°C < 125°C = TJMAX (Control Section Commercial Range) For the Power Transistor: TJ = 75°C + 24W (1°C/W + 0.2°C/W + 1.6°C/W) = 142°C 142°C < 150°C = TJMAX (Power Transistor Commercial Range) In both cases the junction temperature is below the maximum rating for the respective sections, ensuring reliable operation. Junction-to-case thermal resistance is specified from the IC junction to the bottom of the case directly below the die. This is the lowest resistance path for heat flow. Proper mounting is required to ensure the best possible thermal flow from this area of the package to the heat sink. Thermal compound at the case-to-heat sink interface is strongly recommended. If the case of the device must be electronically isolated, a thermally conductive spacer can be used as long as its added contribution to thermal resistance is considered. Note that the case of all devices in this series is electronically connected to the ouput. U TYPICAL APPLICATIONS High Efficiency Regulator 1mH 28V INPUT IN + 470Ω MR1122 1N914 28V 1k OUTPUT GND 10,000µF 10k LT1083-5 OUT 1M 4N28 10k + LT1011 10k – 28V 1N914 LT1083/4/5 TA03 9 LT1083/84/85 Fixed U TYPICAL APPLICATIONS Paralleling Regulators VIN IN 2 FEET #18 WIRE* LT1083-5 OUT GND VOUT = 5V IOUT = 0A TO 15A 0.015Ω IN LT1083-5 OUT *THE #18 WIRE ACTS AS BALLAST RESISTANCE INSURING CURRENT SHARING BETWEEN BOTH DEVICES GND LT1083/4/5 TA04 7.5A Regulator T1 TRIAD F-269U L 1MH C30B IN 20Ω 3 110VAC 20Ω T2 1 4 + C1 1N4003 12V 0A TO 7.5A LT1083-12 OUT + GND 100µF 50,000µF LT1004-1.2 2 C30B 1N914 1N4003 1N4003 1µF 16k* 560Ω 16k* 15V 82k 15k 8 2 –15V + 7 LT1011 10k 1N4148 3 11k* 200k 4 – 0.1µF 1 NC 100pF 15V 8 –15V 4 7 * 1% FILM RESISTOR L-DALE TO-5 TYPE T2-STANCOR 11Z-2003 2N3904 – 3 + 2 1 8 LT1011 10k 6 REGULATOR WITH SCR PREREGULATOR TO LOWER POWER DISSIPATION. ABOUT 1.7V DIFFERENTIAL IS MAINTAINED ACROSS THE LT1083 INDEPENDENT OF LOAD CURRENT. 3 LM301A 1 15k + 7 – 2 4 –15V 15V 11k* 15V 1µF LT1083/4/5 TA05 10 LT1083/84/85 Fixed U TYPICAL APPLICATIONS Adjusting Output Voltage VIN > 12V Regulator with Reference LT1085-5 VIN > 11.5V 5V to 10V + + 100µF 10µF 10V LT1085-5 + + 100µF 10µF 5VOUT + 10µF* LT1029 1k LT1083/4/5 TA06 LT1083/4/5 TA07 *OPTIONAL IMPROVES RIPPLE REJECTION Low Dropout Negative Supply IN VIN LT1084-12 OUT GND + + 100µF 10,000µF VOUT = –12V FLOATING INPUT LT1083/4/5 TA08 Battery Backed Up Regulated Supply VIN 5.2V LINE 5.0V BATTERY LT1084-5 + 10µF 50Ω SELECT FOR CHARGE RATE LT1084-5 6.5V + 10µF + 100µF LT1083/4/5 TA09 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. 11 LT1083/84/85 Fixed U PACKAGE DESCRIPTION Dimension in inches (millimeters) unless otherwise noted. M Package 3-Lead Plastic DD 0.401 ± 0.015 (10.185 ± 0.381) 0.060 (1.524) T Package 3-Lead Plastic TO-220 0.079 – 0.135 (2.007 – 3.429) 0.175 ± 0.008 (4.445 ± 0.203) ( +0.305 8.407 –0.508 +0.008 0.004 –0.004 +0.203 0.102 –0.102 0.059 (1.499) TYP ) ( ( +0.305 3.632 –0.508 0.100 ± 0.010 (2.5402 ± 0.254) 0.050 ± 0.008 (1.270 ± 0.203) ) 0.022 ± 0.005 (0.559 ± 0.127) 0.169 – 0.185 (4.293 – 4.699) 0.035 – 0.055 (0.889 – 1.397) 0.235 – 0.270 (5.969 – 6.858) ) 0.105 ± 0.008 (2.667 ± 0.203) +0.012 0.143 –0.020 0.139 – 0.153 (3.531 – 3.886) DIA 0.050 ± 0.008 (1.270 ± 0.203) 15° TYP +0.012 0.331 –0.020 0.380 – 0.420 (9.652 – 10.668) 0.560 – 0.650 (14.224 – 16.510) 1.005 – 1.080 (25.527 – 27.432) 0.050 ± 0.012 (1.270 ± 0.305) 0.150 3.810 MIN DD3 0693 0.015 – 0.025 (0.381 – 0.635) 0.027 – 0.037 (0.686 – 0.940) 0.050 (1.270) TYP 0.090 – 0.110 (2.286 – 2.794) 0.079 – 0.115 (2.007 – 2.921) T3 0693 K Package 2-Lead TO-3 Metal Can P Package 3-Lead TO-3P Plastic 0.187 – 0.207 (4.75 – 5.26) 0.620 – 0.64O (15.75 – 16.26) 0.760 – 0.775 (19.30 – 19.69) 0.320 – 0.350 (8.13 – 8.89) MOUNTING HOLE 18° – 22° 0.115 – 0.145 (2.92 – 3.68) DIA 0.060 – 0.135 (1.524 – 3.429) 0.170 – 0.2OO (4.32 – 5.08) 0.830 – 0.870 (21.08 – 22.10) 0.420 – 0.480 (10.67 – 12.19) EJECTOR PIN MARKS 0.105 – 0.125 (2.67 – 3.18) DIA 0.580 – 0.6OO (14.73 – 15.24) 0.038 – 0.043 (0.965 – 1.09) 1.177 – 1.197 (29.90 – 30.40) 3° – 7° 0.067 – 0.077 (1.70 – 1.96) 0.210 – 0.220 (5.33 – 5.59) 0.780 – 0.800 0.170 (19.81 – 20.32) (4.32) MAX 0.152 – 0.161 (3.86 – 4.09) DIA 0.167 – 0.177 (4.24 – 4.49) R TYP 0.425 – 0.435 (10.80 – 11.05) 0.655 – 0.675 (16.64 – 17.15) 0.042 – 0.052 (1.07 – 1.32) 0.495 – 0.525 (12.57 – 13.34) 0.215 (5.46) BSC Linear Technology Corporation 0.087 – 0.102 (2.21 – 2.59) 0.020 – 0.040 (0.51 – 1.02) K2 0592 0.074 – 0.084 (1.88 – 2.13) 12 0.060 – 0.080 (1.52 – 2.03) 0.113 – 0.123 (2.87 – 3.12) P3 0892 LT/GP 06/94 5K REV B • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977 © LINEAR TECHNOLOGY CORPORATION 1994