LT1963AEFETRPBF

LT1963A Series 1.5A, Low Noise, Fast Transient Response LDO Regulators FEATURES n n n n n n n n n n n n n n n n DESCRIPTION The LT ®1963A series are low dropout regulators optimized for fast transient response. The devices are capable of supplying 1.5A of output current with a dropout voltage of 340mV. Operating quiescent current is 1mA, dropping to < 1μA in shutdown. Quiescent current is well controlled; it does not rise in dropout as it does with many other regulators. In addition to fast transient response, the LT1963A regulators have very low output noise which makes them ideal for sensitive RF supply applications. Output voltage range is from 1.21V to 20V. The LT1963A regulators are stable with output capacitors as low as 10μF. Internal protection circuitry includes reverse battery protection, current limiting, thermal limiting and reverse current protection. The devices are available in fixed output voltages of 1.5V, 1.8V, 2.5V, 3.3V and as an adjustable device with a 1.21V reference voltage. The LT1963A regulators are available in 5-lead TO-220, DD, 3-lead SOT-223, 8-lead SO and 16-lead TSSOP packages. , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6118263, 6144250. *See Applications Information Section. Optimized for Fast Transient Response Output Current: 1.5A Dropout Voltage: 340mV Low Noise: 40μVRMS (10Hz to 100kHz) 1mA Quiescent Current No Protection Diodes Needed Controlled Quiescent Current in Dropout Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3.3V Adjustable Output from 1.21V to 20V < 1μA Quiescent Current in Shutdown Stable with 10μF Output Capacitor* Stable with Ceramic Capacitors* Reverse Battery Protection No Reverse Current Thermal Limiting 5-Lead TO-220, DD, 3-Lead SOT-223 and 8-Lead SO Packages APPLICATIONS n n 3.3V to 2.5V Logic Power Supplies Post Regulator for Switching Supplies TYPICAL APPLICATION Dropout Voltage 3.3V to 2.5V Regulator DROPOUT VOLTAGE (mV) IN 10μF* OUT 2.5V 1.5A 10μF* 400 350 + VIN > 3V + 300 250 200 150 100 50 0 0 0.2 0.4 0.6 0.8 1.0 1.2 OUTPUT CURRENT (A) 1.4 1.6 1963A TA02 LT1963A-2.5 SHDN SENSE GND 1963A TA01 *TANTALUM, CERAMIC OR ALUMINUM ELECTROLYTIC 1963afd 1 LT1963A Series ABSOLUTE MAXIMUM RATINGS (Note 1) IN Pin Voltage ........................................................ ± 20V OUT Pin Voltage ......................................................±20V Input to Output Differential Voltage (Note 2) ...........±20V SENSE Pin Voltage ............................................... ± 20V ADJ Pin Voltage ...................................................... ±7V SHDN Pin Voltage ................................................. ±20V Output Short-Circuit Duration ........................ Indefinite Operating Junction Temperature Range (Note 3) LT1963AE...........................................– 40°C to 125°C LT1963AI............................................– 40°C to 125°C LT1963AMP .......................................– 55°C to 125°C Storage Temperature Range...................– 65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C PIN CONFIGURATION TOP VIEW GND NC FRONT VIEW 5 4 TAB IS GND 3 2 1 Q PACKAGE 5-LEAD PLASTIC DD SENSE/ADJ* OUT GND IN SHDN TAB IS GND FRONT VIEW 5 4 3 2 1 T PACKAGE 5-LEAD PLASTIC TO-220 SENSE/ ADJ* OUT GND IN SHDN OUT OUT OUT SENSE/ADJ* GND GND 1 2 3 4 5 6 7 8 17 16 GND 15 NC 14 IN 13 IN 12 IN 11 NC 10 SHDN 9 GND *PIN 5 = SENSE FOR LT1963A-1.5/LT1963A-1.8/ LT1963A-2.5/LT1963A-3.3 = ADJ FOR LT1963A TJMAX = 150°C, θJA = 30°C/ W *PIN 5 = SENSE FOR LT1963A-1.5/LT1963A-1.8/ LT1963A-2.5/LT1963A-3.3 = ADJ FOR LT1963A TJMAX = 150°C, θJA = 50°C/ W FE PACKAGE 16-LEAD PLASTIC TSSOP EXPOSED PAD (PIN 17) IS GND. MUST BE SOLDERED TO THE PCB. *PIN 6 = SENSE FOR LT1963A-1.5/LT1963A-1.8/ LT1963A-2.5/LT1963A-3.3 = ADJ FOR LT1963A TJMAX = 150°C, θJA = 38°C/ W FRONT VIEW 3 TAB IS GND 2 1 OUT GND IN OUT 1 SENSE/ADJ* 2 GND 3 NC 4 TOP VIEW 8 7 6 5 IN GND GND SHDN ST PACKAGE 3-LEAD PLASTIC SOT-223 S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 150°C, θJA = 50°C/ W *PIN 2 = SENSE FOR LT1963A-1.5/LT1963A-1.8/ LT1963A-2.5/LT1963A-3.3 = ADJ FOR LT1963A TJMAX = 150°C, θJA = 70°C/ W 1963afd 2 LT1963A Series ORDER INFORMATION LEAD FREE FINISH LT1963AEQ#PBF LT1963AIQ#PBF LT1963AMPQ#PBF LT1963AEQ-1.5#PBF LT1963AEQ-1.8#PBF LT1963AEQ-2.5#PBF LT1963AEQ-3.3#PBF LT1963AET#PBF LT1963AIT#PBF LT1963AET-1.5#PBF LT1963AET-1.8#PBF LT1963AET-2.5#PBF LT1963AET-3.3#PBF LT1963AEFE#PBF LT1963AIFE#PBF LT1963AEFE-1.5#PBF LT1963AEFE-1.8#PBF LT1963AEFE-2.5#PBF LT1963AEFE-3.3#PBF LT1963AEST-1.5#PBF LT1963AEST-1.8#PBF LT1963AEST-2.5#PBF LT1963AEST-3.3#PBF LT1963AES8#PBF LT1963AIS8#PBF LT1963AMPS8#PBF LT1963AES8-1.5#PBF LT1963AES8-1.8#PBF LT1963AES8-2.5#PBF LT1963AES8-3.3#PBF LEAD BASED FINISH LT1963AEQ LT1963AIQ LT1963AMPQ LT1963AEQ-1.5 LT1963AEQ-1.8 LT1963AEQ-2.5 LT1963AEQ-3.3 LT1963AET LT1963AIT TAPE AND REEL LT1963AEQ#TRPBF LT1963AIQ#TRPBF LT1963AMPQ#TRPBF LT1963AEQ-1.5#TRPBF LT1963AEQ-1.8#TRPBF LT1963AEQ-2.5#TRPBF LT1963AEQ-3.3#TRPBF LT1963AET#TRPBF LT1963AIT#TRPBF LT1963AET-1.5#TRPBF LT1963AET-1.8#TRPBF LT1963AET-2.5#TRPBF LT1963AET-3.3#TRPBF LT1963AEFE#TRPBF LT1963AIFE#TRPBF LT1963AEFE-1.5#TRPBF LT1963AEFE-1.8#TRPBF LT1963AEFE-2.5#TRPBF LT1963AEFE-3.3#TRPBF LT1963AEST-1.5#TRPBF LT1963AEST-1.8#TRPBF LT1963AEST-2.5#TRPBF LT1963AEST-3.3#TRPBF LT1963AES8#TRPBF LT1963AIS8#TRPBF LT1963AMPS8#TRPBF LT1963AES8-1.5#TRPBF LT1963AES8-1.8#TRPBF LT1963AES8-2.5#TRPBF LT1963AES8-3.3#TRPBF TAPE AND REEL LT1963AEQ#TR LT1963AIQ#TR LT1963AMPQ#TR LT1963AEQ-1.5#TR LT1963AEQ-1.8#TR LT1963AEQ-2.5#TR LT1963AEQ-3.3#TR LT1963AET#TR LT1963AIT#TR PART MARKING* LT1963AEQ LT1963AIQ LT1963AMPQ LT1963AEQ-1.5 LT1963AEQ-1.8 LT1963AEQ-2.5 LT1963AEQ-3.3 LT1963AET LT1963AIT LT1963AET-1.5 LT1963AET-1.8 LT1963AET-2.5 LT1963AET-3.3 1963AEFE 1963AIFE 1963AEFE15 1963AEFE18 1963AEFE25 1963AEFE33 963A15 963A18 963A25 963A33 1963A 1963A 963AMP 963A15 963A18 963A25 963A33 PART MARKING* LT1963AEQ LT1963AIQ LT1963AMPQ LT1963AEQ-1.5 LT1963AEQ-1.8 LT1963AEQ-2.5 LT1963AEQ-3.3 LT1963AET LT1963AIT PACKAGE DESCRIPTION 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic TO-220 5-Lead Plastic TO-220 5-Lead Plastic TO-220 5-Lead Plastic TO-220 5-Lead Plastic TO-220 5-Lead Plastic TO-220 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP 3-Lead Plastic SOT-223 3-Lead Plastic SOT-223 3-Lead Plastic SOT-223 3-Lead Plastic SOT-223 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO PACKAGE DESCRIPTION 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic DD-PAK 5-Lead Plastic TO-220 5-Lead Plastic TO-220 TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C –55°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –55°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C –55°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C 1963afd 3 LT1963A Series ORDER INFORMATION LEAD BASED FINISH LT1963AET-1.5 LT1963AET-1.8 LT1963AET-2.5 LT1963AET-3.3 LT1963AEFE LT1963AIFE LT1963AEFE-1.5 LT1963AEFE-1.8 LT1963AEFE-2.5 LT1963AEFE-3.3 LT1963AEST-1.5 LT1963AEST-1.8 LT1963AEST-2.5 LT1963AEST-3.3 LT1963AES8 LT1963AIS8 LT1963AMPS8 LT1963AES8-1.5 LT1963AES8-1.8 LT1963AES8-2.5 LT1963AES8-3.3 TAPE AND REEL LT1963AET-1.5#TR LT1963AET-1.8#TR LT1963AET-2.5#TR LT1963AET-3.3#TR LT1963AEFE#TR LT1963AIFE#TR LT1963AEFE-1.5#TR LT1963AEFE-1.8#TR LT1963AEFE-2.5#TR LT1963AEFE-3.3#TR LT1963AEST-1.5#TR LT1963AEST-1.8#TR LT1963AEST-2.5#TR LT1963AEST-3.3#TR LT1963AES8#TR LT1963AIS8#TR LT1963AMPS8#TR LT1963AES8-1.5#TR LT1963AES8-1.8#TR LT1963AES8-2.5#TR LT1963AES8-3.3#TR PART MARKING* LT1963AET-1.5 LT1963AET-1.8 LT1963AET-2.5 LT1963AET-3.3 1963AEFE 1963AIFE 1963AEFE15 1963AEFE18 1963AEFE25 1963AEFE33 963A15 963A18 963A25 963A33 1963A 1963A 963AMP 963A15 963A18 963A25 963A33 PACKAGE DESCRIPTION 5-Lead Plastic TO-220 5-Lead Plastic TO-220 5-Lead Plastic TO-220 5-Lead Plastic TO-220 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP 16-Lead Plastic TSSOP 3-Lead Plastic SOT-223 3-Lead Plastic SOT-223 3-Lead Plastic SOT-223 3-Lead Plastic SOT-223 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –55°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. 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/ 1963afd 4 LT1963A Series ELECTRICAL CHARACTERISTICS PARAMETER Minimum Input Voltage (Notes 4,12) Regulated Output Voltage (Note 5) CONDITIONS ILOAD = 0.5A ILOAD = 1.5A LT1963A-1.5 LT1963A-1.8 LT1963A-2.5 LT1963A-3.3 ADJ Pin Voltage (Notes 4, 5) Line Regulation LT1963A LT1963A-1.5 LT1963A-1.8 LT1963A-2.5 LT1963A-3.3 LT1963A (Note 4) LT1963A-1.5 LT1963A-1.8 LT1963A-2.5 LT1963A-3.3 LT1963A (Note 4) Dropout Voltage VIN = VOUT(NOMINAL) (Notes 6, 7, 12) ILOAD = 1mA ILOAD = 1mA ILOAD = 100mA ILOAD = 100mA ILOAD = 500mA ILOAD = 500mA ILOAD = 1.5A ILOAD = 1.5A GND Pin Current VIN = VOUT(NOMINAL) + 1V (Notes 6, 8) ILOAD = 0mA ILOAD = 1mA ILOAD = 100mA ILOAD = 500mA ILOAD = 1.5A COUT = 10μF, ILOAD = 1.5A, BW = 10Hz to 100kHz (Notes 4, 9) VOUT = Off to On VOUT = On to Off VSHDN = 0V VSHDN = 20V VIN = 6V, VSHDN = 0V ● ● l The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 3) MIN TYP 1.9 2.1 1.477 1.447 1.773 1.737 2.462 2.412 3.250 3.200 1.192 1.174 1.500 1.500 1.800 1.800 2.500 2.500 3.300 3.300 1.210 1.210 2.0 2.5 3.0 3.5 1.5 2 2 2.5 3 2 0.02 0.10 0.19 0.34 1.0 1.1 3.8 15 80 40 3 0.25 0.90 0.75 0.01 3 0.01 10 2 1 30 1 MAX 2.5 1.523 1.545 1.827 1.854 2.538 2.575 3.350 3.400 1.228 1.246 6 7 10 10 5 9 18 10 20 15 30 20 35 8 15 0.06 0.10 0.17 0.22 0.27 0.35 0.45 0.55 1.5 1.6 5.5 25 120 UNITS V V V V V V V V V V V V mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV V V V V V V V V mA mA mA mA mA μVRMS μA V V μA μA μA VIN = 2.21V, ILOAD = 1mA 2.5V < VIN < 20V, 1mA < ILOAD < 1.5A VIN = 2.3V, ILOAD = 1mA 2.8V < VIN < 20V, 1mA < ILOAD < 1.5A VIN = 3V, ILOAD = 1mA 3.5V < VIN < 20V, 1mA < ILOAD < 1.5A VIN = 3.8V, ILOAD = 1mA 4.3V < VIN < 20V, 1mA < ILOAD < 1.5A VIN = 2.21V, ILOAD = 1mA 2.5V < VIN < 20V, 1mA < ILOAD < 1.5A ΔVIN = 2.21V to 20V, ILOAD = 1mA ΔVIN = 2.3V to 20V, ILOAD = 1mA ΔVIN = 3V to 20V, ILOAD = 1mA ΔVIN = 3.8V to 20V, ILOAD = 1mA ΔVIN = 2.21V to 20V, ILOAD = 1mA VIN = 2.5V, ΔILOAD = 1mA to 1.5A VIN = 2.5V, ΔILOAD = 1mA to 1.5A VIN = 2.8V, ΔILOAD = 1mA to 1.5A VIN = 2.8V, ΔILOAD = 1mA to 1.5A VIN = 3.5V, ΔILOAD = 1mA to 1.5A VIN = 3.5V, ΔILOAD = 1mA to 1.5A VIN = 4.3V, ΔILOAD = 1mA to 1.5A VIN = 4.3V, ΔILOAD = 1mA to 1.5A VIN = 2.5V, ΔILOAD = 1mA to 1.5A VIN = 2.5V, ΔILOAD = 1mA to 1.5A l l l l l l l l l l ● ● ● ● ● ● ● ● ● ● ● ● ● ● Load Regulation Output Voltage Noise ADJ Pin Bias Current Shutdown Threshold SHDN Pin Current (Note 10) Quiescent Current in Shutdown 1963afd 5 LT1963A Series ELECTRICAL CHARACTERISTICS PARAMETER Ripple Rejection Current Limit Input Reverse Leakage Current (Note 13) Reverse Output Current (Note 11) CONDITIONS VIN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 0.75A VIN = 7V, VOUT = 0V VIN = VOUT(NOMINAL) + 1V, ΔVOUT = – 0.1V Q, T, S8 Packages ST Package LT1963A-1.5 LT1963A-1.8 LT1963A-2.5 LT1963A-3.3 LT1963A (Note 4) VIN = –20V, VOUT = 0 VIN = –20V, VOUT = 0 VOUT = 1.5V, VIN < 1.5V VOUT = 1.8V, VIN < 1.8V VOUT = 2.5V, VIN < 2.5V VOUT = 3.3V, VIN < 3.3V VOUT = 1.21V, VIN < 1.21V ● ● ● The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 3) MIN 55 TYP 63 2 1.6 1 2 600 600 600 600 300 1200 1200 1200 1200 600 MAX UNITS dB A A mA mA μA μA μA μA 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: Absolute maximum input to output differential voltage can not be achieved with all combinations of rated IN pin and OUT pin voltages. With the IN pin at 20V, the OUT pin may not be pulled below 0V. The total measured voltage from IN to OUT can not exceed ± 20V. Note 3: The LT1963A regulators are tested and specified under pulse load conditions such that TJ ≈ TA. The LT1963AE is 100% tested at TA = 25°C. Performance at –40°C and 125°C is assured by design, characterization and correlation with statistical process controls. The LT1963AI is guaranteed over the full –40°C to 125°C operating junction temperature range. The LT1963AMP is 100% tested and guaranteed over the –55°C to 125°C operating junction temperature range. Note 4: The LT1963A (adjustable version) is tested and specified for these conditions with the ADJ pin connected to the OUT pin. Note 5: 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 6: To satisfy requirements for minimum input voltage, the LT1963A (adjustable version) is tested and specified for these conditions with an external resistor divider (two 4.12k resistors) for an output voltage of 2.4V. The external resistor divider will add a 300μA DC load on the output. Note 7: 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 8: GND pin current is tested with VIN = VOUT(NOMINAL) + 1V and a current source load. The GND pin current will decrease at higher input voltages. Note 9: ADJ pin bias current flows into the ADJ pin. Note 10: SHDN pin current flows into the SHDN pin. Note 11: 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 12: For the LT1963A, LT1963A-1.5 and LT1963A-1.8 dropout voltage will be limited by the minimum input voltage specification under some output voltage/load conditions. Note 13: For the ST package, the input reverse leakage current increases due to the additional reverse leakage current for the SHDN pin, which is tied internally to the IN pin. 1963afd 6 LT1963A Series TYPICAL PERFORMANCE CHARACTERISTICS Typical Dropout Voltage 500 450 400 Guaranteed Dropout Voltage 600 Dropout Voltage 500 450 GUARANTEED DROPOUT VOLTAGE (mV) = TEST POINTS 500 350 300 250 200 150 100 50 0 0 0.2 DROPOUT VOLTAGE (mV) DROPOUT VOLTAGE (mV) TJ ≤ 125°C 400 TJ ≤ 25°C 300 200 100 0 400 350 300 250 200 150 100 50 IL = 100mA IL = 1mA –25 50 25 0 75 TEMPERATURE (°C) 100 125 IL = 0.5A IL = 1.5A TJ = 125°C TJ = 25°C 0.4 0.6 0.8 1.0 1.2 OUTPUT CURRENT (A) 1.4 1.6 0 0.2 0.4 0.6 0.8 1.0 1.2 OUTPUT CURRENT (A) 1.4 1.6 0 –50 1963A G01 1963A G02 1963A G03 Quiescent Current 1.4 1.2 QUIESCENT CURRENT (mA) LT1963A-1.5 Output Voltage 1.54 IL = 1mA 1.84 LT1963A-1.8 Output Voltage IL = 1mA 1.83 OUTPUT VOLTAGE (V) LT1963A-1.5/1.8/-2.5/-3.3 OUTPUT VOLTAGE (V) 1.53 1.52 1.51 1.50 1.49 1.48 1.47 100 125 1.0 0.8 0.6 0.4 0.2 VIN = 6V RL = ∞, IL = 0 VSHDN = VIN 50 25 75 0 TEMPERATURE (°C) LT1963A 1.82 1.81 1.80 1.79 1.78 1.77 0 –50 –25 1.46 –50 –25 0 75 50 25 TEMPERATURE (°C) 100 125 1.76 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) 1963A G40 1963A G05 1963A G04 LT1963A-2.5 Output Voltage 2.58 IL = 1mA 2.56 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) LT1963A-3.3 Output Voltage 3.38 IL = 1mA 3.36 ADJ PIN VOLTAGE (V) LT1963A ADJ Pin Voltage 1.230 IL = 1mA 1.225 1.220 1.215 1.210 1.205 1.200 1.195 2.54 2.52 2.50 2.48 2.46 2.44 2.42 –50 –25 0 25 50 75 100 125 3.34 3.32 3.30 3.28 3.26 3.24 3.22 –50 –25 0 25 50 75 100 125 1.190 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) 1963A G06 TEMPERATURE (°C) 1963A G07 TEMPERATURE (°C) 1963A G08 1963afd 7 LT1963A Series TYPICAL PERFORMANCE CHARACTERISTICS LT1963A-1.5 Quiescent Current 14 TJ = 25°C R =∞ 12 L VSHDN = VIN 10 8 6 4 2 0 0 1 2 3456 7 INPUT VOLTAGE (V) 8 9 14 12 LT1963A-1.8 Quiescent Current TJ = 25°C RL = ∞ VSHDN = VIN 14 12 LT1963A-2.5 Quiescent Current TJ = 25°C RL = ∞ VSHDN = VIN QUIESCENT CURRENT (mA) QUIESCENT CURRENT (mA) QUIESCENT CURRENT (mA) 10 8 6 4 2 0 0 1 2 10 8 6 4 2 0 10 34567 INPUT VOLTAGE (V) 8 9 10 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 1963A G41 1963A G09 1963A G10 LT1963A-3.3 Quiescent Current 14 12 TJ = 25°C RL = ∞ VSHDN = VIN LT1963A Quiescent Current 1.4 1.2 25 LT1963A-1.5 GND Pin Current TJ = 25°C VSHDN = VIN *FOR VOUT = 1.5V QUIESCENT CURRENT (mA) QUIESCENT CURRENT (mA) TJ = 25°C RL = 4.3k VSHDN = VIN GND PIN CURRENT (mA) 20 10 8 6 4 2 0 0 1 2 1.0 0.8 0.6 0.4 0.2 15 RL = 150, IL = 10mA* 10 RL = 5, IL = 300mA* RL = 15, IL = 100mA* 5 34567 INPUT VOLTAGE (V) 8 9 10 0 0 2 4 0 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 1963A G12 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 1963A G11 1963A G42 LT1963A-1.8 GND Pin Current 25 TJ = 25°C VSHDN = VIN 20 *FOR VOUT = 1.8V GND PIN CURRENT (mA) LT1963A-2.5 GND Pin Current 25 25 TJ = 25°C VSHDN = VIN *FOR VOUT = 2.5V GND PIN CURRENT (mA) LT1963A-3.3 GND Pin Current TJ = 25°C VSHDN = VIN *FOR VOUT = 3.3V GND PIN CURRENT (mA) 20 20 15 15 15 RL = 11, IL = 300mA* RL = 8.33, IL = 300mA* 10 RL = 6, IL = 300mA* RL = 18, IL = 100mA* RL = 180, IL = 10mA* 10 RL = 25, IL = 100mA* 10 5 5 5 RL = 33, IL = 100mA* RL = 330, IL = 100mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 1963A G15 0 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 1963A G13 0 0 1 2 RL = 250, IL = 10mA* 34567 INPUT VOLTAGE (V) 8 9 10 1963A G14 0 1963afd 8 LT1963A Series TYPICAL PERFORMANCE CHARACTERISTICS LT1963A GND Pin Current 10 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.21V 100 90 LT1963A-1.5 GND Pin Current 100 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.5V 90 LT1963A-1.8 GND Pin Current TJ = 25°C VSHDN = VIN *FOR VOUT = 1.8V GND PIN CURRENT (mA) GND PIN CURRENT (mA) GND PIN CURRENT (mA) 8 80 70 60 50 40 30 20 80 70 60 50 40 30 20 10 0 6 RL = 4.33, IL = 300mA* RL = 1, IL = 1.5A* RL = 1.5, IL = 1A* RL = 1.2, IL = 1.5A* 4 RL = 12.1, IL = 100mA* 2 RL = 121, IL = 10mA* 0 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 1963A G16 RL = 1.8, IL = 1A* RL = 3, IL = 500mA* 10 0 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 RL = 3.6, IL = 500mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 1963A G43 1963A G17 LT1963A-2.5 GND Pin Current 100 90 TJ = 25°C VSHDN = VIN *FOR VOUT = 2.5V RL = 1.67, IL = 1.5A* 100 90 LT1963A-3.3 GND Pin Current TJ = 25°C VSHDN = VIN *FOR VOUT = 3.3V LT1963A GND Pin Current 100 90 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.21V GND PIN CURRENT (mA) GND PIN CURRENT (mA) 70 60 50 40 30 20 10 0 0 1 2 70 60 50 40 30 20 GND PIN CURRENT (mA) 80 80 80 70 60 50 40 30 20 RL = 2.2, IL = 1.5A* RL = 0.81, IL = 1.5A* RL = 2.5, IL = 1A* RL = 3.3, IL = 1A* RL = 1.21, IL = 1A* RL = 2.42, IL = 500mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 RL = 5, IL = 500mA* 34567 INPUT VOLTAGE (V) 8 9 10 10 0 0 1 2 RL = 6.6, IL = 500mA* 34567 INPUT VOLTAGE (V) 8 9 10 10 0 1963A G18 1963A G19 1963A G20 GND Pin Current vs ILOAD 100 90 SHDN Pin Threshold (On-to-Off) 1.0 0.9 IL = 1mA 1.0 0.9 SHDN Pin Threshold (Off-to-On) IL = 1.5A VIN = VOUT (NOMINAL) +1V SHDN PIN THRESHOLD (V) 70 60 50 40 30 20 10 0 0 0.2 0.4 0.6 0.8 1.0 1.2 OUTPUT CURRENT (A) 1.4 1.6 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 SHDN PIN THRESHOLD (V) GND PIN CURRENT (mA) 80 0.8 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 IL = 1mA 1963A G21 1963A G22 1963A G23 1963afd 9 LT1963A Series TYPICAL PERFORMANCE CHARACTERISTICS SHDN Pin Input Current 5.0 4.5 7 SHDN PIN INPUT CURRENT (μA) SHDN Pin Input Current VSHDN = 20V ADJ PIN BIAS CURRENT (μA) ADJ Pin Bias Current 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 SHDN PIN INPUT CURRENT (μA) 6 5 4 3 2 1 0 –50 –25 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 2 4 6 8 10 12 14 16 18 20 SHDN PIN VOLTAGE (V) 1963A G24 50 25 75 0 TEMPERATURE (°C) 100 125 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 1963A G25 1963A G26 Current Limit 3.0 2.5 Current Limit 4.0 VIN = 7V 3.5 VOUT = 0V CURRENT LIMIT (A) 2.0 TJ = 125°C 1.5 1.0 0.5 ΔVOUT = 100mV 0 0 2 TJ = –50°C CURRENT LIMIT (A) TJ = 25°C 3.0 2.5 2.0 1.5 1.0 0.5 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 4 6 8 10 12 14 16 18 20 INPUT/OUTPUT DIFFERENTIAL (V) 1963A G27 1963A G28 Reverse Output Current 5.0 REVERSE OUTPUT CURRENT (mA) Reverse Output Current 1.0 VIN = 0V 0.9 VOUT = 1.21V (LT1963A) V = 1.5V (LT1963A-1.5) 0.8 VOUT = 1.8V (LT1963A-1.8) OUT 0.7 VOUT = 2.5V (LT1963A-2.5) VOUT = 3.3V (LT1963A-3.3) 0.6 LT1963A-1.8/-2.5/-3.3 0.5 0.4 0.3 0.2 0.1 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 LT1963A LT1963A-1.8 LT1963A-1.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 LT1963A LT1963A-3.3 T = 25°C J VIN = 0V LT1963A-2.5 CURRENT FLOWS INTO OUTPUT PIN VOUT = VADJ (LT1963A) VOUT = VFB (LT1963A-1.5/1.8/-2.5/-3.3) 1 2 345678 OUTPUT VOLTAGE (V) 9 10 1963A G29 REVERSE OUTPUT CURRENT (mA) 4.5 1963A G30 1963afd 10 LT1963A Series TYPICAL PERFORMANCE CHARACTERISTICS Ripple Rejection 80 70 76 74 RIPPLE REJECTION (dB) Ripple Rejection 3.0 2.5 2.0 1.5 1.0 0.5 LT1963A Minimum Input Voltage MINIMUM INPUT VOLTAGE (V) RIPPLE REJECTION (dB) 60 50 40 30 20 COUT = 100μF TANTALUM +10 × 1μF CERAMIC COUT = 10μF TANTALUM IL = 1.5A 72 70 68 66 64 IL = 0.75A VIN = VOUT(NOMINAL) +1V + 0.5VP-P RIPPLE AT f = 120Hz 62 50 100 25 75 –50 –25 0 TEMPERATURE (°C) IL = 500mA IL = 100mA 10 IL = 0.75A VIN = VOUT(NOMINAL) +1V + 50mVRMS RIPPLE 0 100 100k 10 1k 10k 1M FREQUENCY (Hz) 1963A G31 125 0 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 1963A G32 1963A G33 Load Regulation OUTPUT NOISE SPECTRAL DENSITY (μV/√Hz) 10 5 LOAD REGULATION (mV) Output Noise Spectral Density 1.0 COUT = 10μF IL =1.5A LT1963A-1.5 LT1963A LT1963A-1.8 0 –5 –10 –15 LT1963A-3.3 0.1 LT1963A-2.5 LT1963A-2.5 LT1963A-3.3 VIN = VOUT(NOMINAL) +1V (LT1963A-1.8/-2.5/-3.3) VIN = 2.7V (LT1963A/LT1963A-1.5) ΔIL = 1mA TO 1.5A 50 25 75 0 TEMPERATURE (°C) 100 125 LT1963A-1.8 LT1963A-1.5 0.01 10 100 LT1963A –20 –50 –25 1k 10k FREQUENCY (Hz) 100k 1963A G35 1963A G34 RMS Output Noise vs Load Current (10Hz to 100kHz) 50 LT1963A-3.3 10Hz to 100kHz Output Noise OUTPUT NOISE VOLTAGE (μVRMS) 45 40 35 30 25 20 15 10 5 COUT = 10μF LT1963A-3.3 LT1963A-2.5 LT1963A-1.8 LT1963A-1.5 LT1963A VOUT 100μV/DIV 0 0.0001 0.001 0.01 0.1 LOAD CURRENT (A) 1 10 1963A G36 COUT = 10μF ILOAD = 1.5A 1ms/DIV 1963A G37 1963afd 11 LT1963A Series TYPICAL PERFORMANCE CHARACTERISTICS LT1963A-3.3 Transient Response 200 OUTPUT VOLTAGE DEVIATION (mV) OUTPUT VOLTAGE DEVIATION (mV) LT1963A-3.3 Transient Response 150 100 50 0 –50 VIN = 4.3V 150 CIN = 3.3μF TANTALUM COUT = 10μF TANTALUM 100 50 0 –50 –100 –150 –100 LOAD CURRENT (A) LOAD CURRENT (A) 0.6 0.4 0.2 0 0 2 4 6 8 10 12 14 16 18 20 TIME (μs) 1963A G38 1.5 1.0 0.5 0 0 VIN = 4.3V CIN = 33μF TANTALUM COUT = 100μF TANTALUM +10 × 1μF CERAMIC 50 100 150 200 250 300 350 400 450 500 TIME (μs) 1963A G39 1963afd 12 LT1963A Series PIN FUNCTIONS OUT: Output. The output supplies power to the load. A minimum output capacitor of 10μF 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. SENSE: Sense. For fixed voltage versions of the LT1963A (LT1963A-1.5/LT1963A-1.8/LT1963A-2.5/LT1963A-3.3), the SENSE pin is the input to the error amplifier. Optimum regulation will be obtained at the point where the SENSE pin is connected to the OUT pin of the regulator. In critical applications, small voltage drops are caused by the resistance (RP) of PC traces between the regulator and the load. These may be eliminated by connecting the SENSE pin to the output at the load as shown in Figure 1 (Kelvin Sense Connection). Note that the voltage drop across the external PC traces will add to the dropout voltage of the regulator. The SENSE pin bias current is 600μA at the nominal rated output voltage. The SENSE pin can be pulled below ground (as in a dual supply system where the regulator load is returned to a negative supply) and still allow the device to start and operate. ADJ: Adjust. For the adjustable LT1963A, this is the input to the error amplifier. This pin is internally clamped to ± 7V. It has a bias current of 3μA which flows into the pin. The ADJ pin voltage is 1.21V referenced to ground and the output voltage range is 1.21V to 20V. SHDN: Shutdown. The SHDN pin is used to put the LT1963A regulators 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 required to supply the pull-up current of the open-collector gate, normally several microamperes, and the SHDN pin current, typically 3μA. If unused, the SHDN pin must be connected to VIN. The device will be in the low power shutdown state if the SHDN pin is not connected. IN: 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 LT1963A regulators are designed to withstand reverse voltages on the IN pin with respect to ground and the OUT pin. In the case of a reverse input, which can happen if a battery is plugged in backwards, the device will act as if there is a diode in series with its input. There will be no reverse current flow into the regulator and no reverse voltage will appear at the load. The device will protect both itself and the load. IN OUT LT1963A RP + VIN SHDN SENSE GND RP + LOAD 1963A F01 Figure 1. Kelvin Sense Connection 1963afd 13 LT1963A Series APPLICATIONS INFORMATION The LT1963A series are 1.5A low dropout regulators optimized for fast transient response. The devices are capable of supplying 1.5A at a dropout voltage of 350mV. The low operating quiescent current (1mA) drops to less than 1μA in shutdown. In addition to the low quiescent current, the LT1963A regulators incorporate several protection features which make them ideal for use in battery-powered systems. The devices are 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 LT1963A-X acts like it has a diode in series with its output and prevents reverse current flow. Additionally, in dual supply applications where the regulator load is returned to a negative supply, the output can be pulled below ground by as much as 20V and still allow the device to start and operate. Adjustable Operation The adjustable version of the LT1963A has an output voltage range of 1.21V to 20V. 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 ADJ pin at 1.21V referenced to ground. The current in R1 is then equal to 1.21V/R1 and the current in R2 is the current in R1 plus the ADJ pin bias current. The ADJ pin bias current, 3μA at 25°C, flows through R2 into the ADJ pin. The output voltage can be calculated using the formula in Figure 2. The value of R1 should be less than 4.17k 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 adjustable device is tested and specified with the ADJ pin tied to the OUT pin for an output voltage of 1.21V. Specifications for output voltages greater than 1.21V will be proportional to the ratio of the desired output voltage to 1.21V: VOUT/1.21V. For example, load regulation for an output current change of 1mA to 1.5A is – 3mV typical at VOUT = 1.21V. At VOUT = 5V, load regulation is: (5V/1.21V)(–3mV) = –12.4mV Output Capacitors and Stability The LT1963A regulator is a feedback circuit. Like any feedback circuit, frequency compensation is needed to IN VIN OUT LT1963A ADJ GND R1 R2 VOUT + VOUT = 1.21V 1+ VADJ = 1.21V IADJ = 3μA AT 25°C OUTPUT RANGE = 1.21V TO 20V R2 + (IADJ ) (R2) R1 1963A F02 Figure 2. Adjustable Operation make it stable. For the LT1963A, the frequency compensation is both internal and external—the output capacitor. The size of the output capacitor, the type of the output capacitor, and the ESR of the particular output capacitor all affect the stability. In addition to stability, the output capacitor also affects the high frequency transient response. The regulator loop has a finite band width. For high frequency transient loads, recovery from a transient is a combination of the output capacitor and the bandwidth of the regulator. The LT1963A was designed to be easy to use and accept a wide variety of output capacitors. However, the frequency compensation is affected by the output capacitor and optimum frequency stability may require some ESR, especially with ceramic capacitors. For ease of use, low ESR polytantalum capacitors (POSCAP) are a good choice for both the transient response and stability of the regulator. These capacitors have intrinsic ESR that improves the stability. Ceramic capacitors have extremely low ESR, and while they are a good choice in many cases, placing a small series resistance element will sometimes achieve optimum stability and minimize ringing. In all cases, a minimum of 10μF is required while the maximum ESR allowable is 3Ω. The place where ESR is most helpful with ceramics is low output voltage. At low output voltages, below 2.5V, some ESR helps the stability when ceramic output capacitors are used. Also, some ESR allows a smaller capacitor value to be used. When small signal ringing occurs with ceramics due to insufficient ESR, adding ESR or increasing the capacitor value improves the stability and reduces the ringing. Table 1 gives some recommended values of ESR to minimize ringing caused by fast, hard current transitions. 1963afd 14 LT1963A Series APPLICATIONS INFORMATION Table 1. Capacitor Minimum ESR VOUT 1.2V 1.5V 1.8V 2.5V 3.3V ≥5V 10μF 20mΩ 20mΩ 15mΩ 5mΩ 0mΩ 0mΩ 22μF 15mΩ 15mΩ 10mΩ 5mΩ 0mΩ 0mΩ 47μF 10mΩ 10mΩ 10mΩ 5mΩ 0mΩ 0mΩ 100μF 5mΩ 5mΩ 5mΩ 5mΩ 5mΩ 0mΩ POSCAP capacitors are used. The output voltage is at the worst case value of 1.2V. Trace A, is with a 10μF ceramic output capacitor and shows significant ringing with a peak amplitude of 25mV. For Trace B, a 22μF/45mΩ POSCAP is added in parallel with the 10μF ceramic. The output is well damped and settles to within 10mV in less than 20μs. For Trace C, a 100μF/35mΩ POSCAP is connected in parallel with the 10μF ceramic capacitor. In this case the peak output deviation is less than 20mV and the output settles in about 10μs. For improved transient response the value of the bulk capacitor (tantalum or aluminum electrolytic) should be greater than twice the value of the ceramic capacitor. Tantalum and Polytantalum Capacitors There is a variety of tantalum capacitor types available, with a wide range of ESR specifications. Older types have ESR specifications in the hundreds of mΩ to several Ohms. Some newer types of polytantalum with multi-electrodes have maximum ESR specifications as low as 5mΩ. In general the lower the ESR specification, the larger the size and the higher the price. Polytantalum capacitors have better surge capability than older types and generally lower ESR. Some types such as the Sanyo TPE and TPB series have ESR specifications in the 20mΩ to 50mΩ range, which provide near optimum transient response. Aluminum Electrolytic Capacitors Aluminum electrolytic capacitors can also be used with the LT1963A. These capacitors can also be used in conjunction with ceramic capacitors. These tend to be the cheapest and lowest performance type of capacitors. Care must be used in selecting these capacitors as some types can have ESR which can easily exceed the 3Ω maximum value. Ceramic Capacitors Extra consideration must be given to the use of ceramic capacitors. Ceramic capacitors are manufactured with a variety of dielectrics, each with different behavior over temperature and applied voltage. The most common dielectrics used are Z5U, Y5V, X5R and X7R. The Z5U and 1963afd Figures 3 through 8 show the effect of ESR on the transient response of the regulator. These scope photos show the transient response for the LT1963A at three different output voltages with various capacitors and various values of ESR. The output load conditions are the same for all traces. In all cases there is a DC load of 500mA. The load steps up to 1A at the first transition and steps back to 500mA at the second transition. At the worst case point of 1.2VOUT with 10μF COUT (Figure 3), a minimum amount of ESR is required. While 20mΩ is enough to eliminate most of the ringing, a value closer to 50mΩ provides a more optimum response. At 2.5V output with 10μF COUT (Figure 4) the output rings at the transitions with 0Ω ESR but still settles to within 10mV in 20μs after the 0.5A load step. Once again a small value of ESR will provide a more optimum response. At 5VOUT with 10μF COUT (Figure 5) the response is well damped with 0Ω ESR. With a COUT of 100μF at 0Ω ESR and an output of 1.2V (Figure 6), the output rings although the amplitude is only 20mVp-p. With COUT of 100μF it takes only 5mΩ to 20mΩ of ESR to provide good damping at 1.2V output. Performance at 2.5V and 5V output with 100μF COUT shows similar characteristics to the 10μF case (see Figures 7-8). At 2.5VOUT 5mΩ to 20mΩ can improve transient response. At 5VOUT the response is well damped with 0Ω ESR. Capacitor types with inherently higher ESR can be combined with 0mΩ ESR ceramic capacitors to achieve both good high frequency bypassing and fast settling time. Figure 9 illustrates the improvement in transient response that can be seen when a parallel combination of ceramic and 15 LT1963A Series APPLICATIONS INFORMATION 0 20 RESR (mΩ) 50mV/DIV VOUT = 1.2V IOUT = 500mA WITH 500mA PULSE COUT = 10μF RESR (mΩ) 0 5 50mV/DIV VOUT = 1.2V IOUT = 500mA WITH 500mA PULSE COUT = 100μF 50 10 100 20 20μs/DIV 1963A F03 1963A F06 50μs/DIV Figure 3 Figure 6 0 20 RESR (mΩ) 50mV/DIV VOUT = 2.5V IOUT = 500mA WITH 500mA PULSE COUT = 10μF RESR (mΩ) 0 5 50mV/DIV VOUT = 2.5V IOUT = 500mA WITH 500mA PULSE COUT = 100μF 50 10 100 20 20μs/DIV 1963A F04 50μs/DIV 1963A F07 Figure 4 Figure 7 0 20 50mV/DIV RESR (mΩ) VOUT = 5V IOUT = 500mA WITH 500mA PULSE COUT = 10μF RESR (mΩ) 0 5 50mV/DIV VOUT = 5V IOUT = 500mA WITH 500mA PULSE COUT = 100μF 50 10 100 20 20μs/DIV 1963A F05 1963A F08 50μs/DIV Figure 5 A Figure 8 B 50mV/DIV RESR (mΩ) VOUT = 1.2V IOUT = 500mA WITH 500mA PULSE COUT = A = 10μF CERAMIC B = 10μF CERAMIC II 22μF/45mΩ POLY C = 10μF CERAMIC II 100μF/35mΩ POLY C 50μs/DIV 1963A F09 Figure 9 1963afd 16 LT1963A Series APPLICATIONS INFORMATION Y5V dielectrics are good for providing high capacitances in a small package, but exhibit strong voltage and temperature coefficients as shown in Figures 10 and 11. 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, 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. Table 2. PC Trace Resistors 10mΩ 0.5oz CU 1.0oz CU 2.0oz CU Width Length Width Length Width Length 0.011" (0.28mm) 0.102" (2.6mm) 0.006" (0.15mm) 0.110" (2.8mm) 0.006" (0.15mm) 0.224" (5.7mm) 20mΩ 0.011" (0.28mm) 0.204" (5.2mm) 0.006" (0.15mm) 0.220" (5.6mm) 0.006" (0.15mm) 0.450" (11.4mm) 30mΩ 0.011" (0.28mm) 0.307" (7.8mm) 0.006" (0.15mm) 0.330" (8.4mm) 0.006" (0.15mm) 0.670" (17mm) “FREE” Resistance with PC Traces The resistance values shown in Table 2 can easily be made using a small section of PC trace in series with the output capacitor. The wide range of non-critical ESR makes it easy to use PC trace. The trace width should be sized to handle the RMS ripple current associated with the load. The output capacitor only sources or sinks current for a few microseconds during fast output current transitions. There is no DC current in the output capacitor. Worst case ripple current will occur if the output load is a high frequency (>100kHz) square wave with a high peak value and fast edges (< 1μs). Measured RMS value for this case is 0.5 times the peak-to-peak current change. Slower edges or lower frequency will significantly reduce the RMS ripple current in the capacitor. 20 0 CHANGE IN VALUE (%) BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10μF CHANGE IN VALUE (%) 40 20 0 –20 –40 –60 –80 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10μF 50 25 75 0 TEMPERATURE (°C) 100 125 Y5V X5R X5R –20 –40 –60 Y5V –80 –100 0 2 4 8 6 10 12 DC BIAS VOLTAGE (V) 14 16 –100 –50 –25 1963A F10 1963A F11 Figure 10. Ceramic Capacitor DC Bias Characteristics Figure 11. Ceramic Capacitor Temperature Characteristics 1963afd 17 LT1963A Series APPLICATIONS INFORMATION This resistor should be made using one of the inner layers of the PC board which are well defined. The resistivity is determined primarily by the sheet resistance of the copper laminate with no additional plating steps. Table 2 gives some sizes for 0.75A RMS current for various copper thicknesses. More detailed information regarding resistors made from PC traces can be found in Application Note 69, Appendix A. Overload Recovery Like many IC power regulators, the LT1963A-X has safe operating 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 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 voltage is rising, the input-to-output voltage differential is small, allowing the regulator to supply large output currents. With a high input voltage, a problem can occur wherein removal of an output short will not allow the output voltage to recover. Other regulators, such as the LT1085, also exhibit this phenomenon, so it is not unique to the LT1963A-X. The problem occurs with a heavy output load when the input voltage is high and the output voltage is low. Common situations are immediately after the removal of a shortcircuit or when the shutdown pin is pulled high after the input voltage has already been turned on. 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 input power supply may need to be cycled down to zero and brought up again to make the output recover. Output Voltage Noise The LT1963A regulators have been designed to provide low output voltage noise over the 10Hz to 100kHz bandwidth while operating at full load. Output voltage noise is typically 40nV/√Hz over this frequency bandwidth for the LT1963A (adjustable version). For higher output voltages (generated by using a resistor divider), the output voltage noise will be gained up accordingly. This results in RMS noise over the 10Hz to 100kHz bandwidth of 14μVRMS for the LT1963A increasing to 38μVRMS for the LT1963A-3.3. Higher values of output voltage noise may be measured when care is not exercised with regard to circuit layout and testing. Crosstalk from nearby traces can induce unwanted noise onto the output of the LT1963A-X. Power supply ripple rejection must also be considered; the LT1963A regulators do not have unlimited power supply rejection and will pass a small portion of the input noise through to the output. Thermal Considerations The power handling capability of the device is limited by the maximum rated junction temperature (125°C). The power dissipated by the device is 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 using 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 LT1963A series regulators have 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. 1963afd 18 LT1963A Series APPLICATIONS INFORMATION The following tables list thermal resistance for several different board sizes and copper areas. All measurements were taken in still air on 1/16" FR-4 board with one ounce copper. Table 3. Q Package, 5-Lead DD COPPER AREA TOPSIDE* BACKSIDE 2500mm2 1000mm2 125mm2 2500mm2 2500mm2 2500mm2 BOARD AREA 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 23°C/W 25°C/W 33°C/W The power dissipated by the device will be equal to: IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)) where, IOUT(MAX) = 500mA VIN(MAX) = 6V IGND at (IOUT = 500mA, VIN = 6V) = 10mA So, P = 500mA(6V – 3.3V) + 10mA(6V) = 1.41W Using a DD package, the thermal resistance will be in the range of 23°C/W to 33°C/W depending on the copper area. So the junction temperature rise above ambient will be approximately equal to: 1.41W(28°C/W) = 39.5°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 + 39.5°C = 89.5°C Protection Features *Device is mounted on topside Table 4. S0-8 Package, 8-Lead SO COPPER AREA TOPSIDE* BACKSIDE 2500mm2 1000mm2 225mm2 125mm2 2500mm2 2500mm2 2500mm2 2500mm2 BOARD AREA 2500mm2 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 55°C/W 55°C/W 63°C/W 69°C/W *Device is mounted on topside Table 5. SOT-223 Package, 3-Lead SOT-223 COPPER AREA TOPSIDE* BACKSIDE 2500mm2 1000mm2 225mm2 100mm2 1000mm2 1000mm2 2500mm2 2500mm2 2500mm2 2500mm2 1000mm2 0mm2 BOARD AREA 2500mm2 2500mm2 2500mm2 2500mm2 1000mm2 1000mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 42°C/W 42°C/W 50°C/W 56°C/W 49°C/W 52°C/W The LT1963A regulators incorporate several protection features which make them 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 devices are protected against reverse input voltages, reverse output 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 20V. Current flow into the device will be limited to less than 1mA (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 that can be plugged in backward. *Device is mounted on topside T Package, 5-Lead TO-220 Thermal Resistance (Junction-to-Case) = 4°C/W Calculating Junction Temperature Example: Given an output voltage of 3.3V, an input voltage range of 4V to 6V, an output current range of 0mA to 500mA and a maximum ambient temperature of 50°C, what will the maximum junction temperature be? 1963afd 19 LT1963A Series APPLICATIONS INFORMATION The output of the LT1963A can be pulled below ground without damaging the device. If the input is left open circuit or grounded, the output can be pulled below ground by 20V. For fixed voltage versions, the output will act like a large resistor, typically 5k or higher, limiting current flow to typically less than 600μA. For adjustable versions, the output will act like an open circuit; no current will flow out of the pin. If the input is powered by a voltage source, the output will source the short-circuit current of the device and will protect itself by thermal limiting. In this case, grounding the SHDN pin will turn off the device and stop the output from sourcing the short-circuit current. The ADJ pin of the adjustable 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 5k) in series with a diode when pulled above ground. 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 1.21V reference when the output is forced to 20V. 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 13V difference between OUT and ADJ pins divided by the 5mA maximum current into the ADJ pin yields a minimum top resistor value of 2.6k. 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 12. When the IN pin of the LT1963A 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 device 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. 5.0 LT1963A VOUT = VADJ REVERSE OUTPUT CURRENT (mA) 4.5 4.0 LT1963A-1.5 VOUT = VFB 3.5 LT1963A-1.8 3.0 VOUT = VFB 2.5 LT1963A-2.5 VOUT = VFB 2.0 1.5 1.0 0.5 0 0 1 2 LT1963A-3.3 VOUT = VFB TJ = 25°C VIN = 0V CURRENT FLOWS INTO OUTPUT PIN 9 10 345678 OUTPUT VOLTAGE (V) 1963A F12 Figure 12. Reverse Output Current 1963afd 20 LT1963A Series TYPICAL APPLICATIONS SCR Pre-Regulator Provides Efficiency Over Line Variations L1 500μH L2 10VAC AT 115VIN 90-140 VAC 10VAC AT 115VIN 1N4148 1k 34k* LT1963A-3.3 IN OUT + 10000μF SHDN GND FB + 3.3VOUT 1.5A 22μF 1N4002 “SYNC” 1N4002 TO ALL “+V” POINTS + 22μF 1N4002 +V 2.4k 12.1k* + 750Ω C1A 1/2 LT1018 1N4148 200k – +V C1B 0.033μF 750Ω 0.1μF +V 1N4148 LT1006 10k 1μF +V L1 = COILTRONICS CTX500-2-52 L2 = STANCOR P-8559 * = 1% FILM RESISTOR = NTE5437 – + 10k 10k +V LT1004 1.2V 1963A TA03 1/2 LT1018 – + A1 1963afd 21 LT1963A Series TYPICAL APPLICATIONS Paralleling of Regulators for Higher Output Current R1 0.01Ω + VIN > 3.7V LT1963A-3.3 IN OUT C1 100μF + SHDN GND FB 3.3V 3A C2 22μF R2 0.01Ω IN SHDN LT1963A OUT R6 6.65k SHDN GND FB R7 4.12k R3 2.2k R4 2.2k 3 R5 1k + – 8 1/2 LT1366 4 1 C3 0.01μF 1963A TA05 2 1963afd 22 LT1963A Series PACKAGE DESCRIPTION Q Package 5-Lead Plastic DD Pak (Reference LTC DWG # 05-08-1461) .256 (6.502) .060 (1.524) .060 (1.524) TYP .390 – .415 (9.906 – 10.541) 15° TYP .165 – .180 (4.191 – 4.572) .045 – .055 (1.143 – 1.397) .060 (1.524) .183 (4.648) .330 – .370 (8.382 – 9.398) .059 (1.499) TYP ( +.008 .004 –.004 +0.203 0.102 –0.102 ) .075 (1.905) .300 (7.620) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK +.012 .143 –.020 +0.305 3.632 –0.508 .067 (1.702) .028 – .038 BSC (0.711 – 0.965) TYP .013 – .023 (0.330 – 0.584) .095 – .115 (2.413 – 2.921) .050 ± .012 (1.270 ± 0.305) Q(DD5) 0502 ( ) .420 .080 .420 .276 .350 .205 .565 .325 .565 .320 .090 .067 .042 .067 .090 .042 RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS IN INCH/(MILLIMETER) 2. DRAWING NOT TO SCALE RECOMMENDED SOLDER PAD LAYOUT FOR THICKER SOLDER PASTE APPLICATIONS 1963afd 23 LT1963A Series PACKAGE DESCRIPTION S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .045 ±.005 .050 BSC 8 .189 – .197 (4.801 – 5.004) NOTE 3 7 6 5 .245 MIN .160 ±.005 .228 – .244 (5.791 – 6.197) .150 – .157 (3.810 – 3.988) NOTE 3 .030 ±.005 TYP RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) 0°– 8° TYP 1 2 3 4 .053 – .069 (1.346 – 1.752) .004 – .010 (0.101 – 0.254) .016 – .050 (0.406 – 1.270) NOTE: 1. DIMENSIONS IN INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) .014 – .019 (0.355 – 0.483) TYP .050 (1.270) BSC SO8 0303 1963afd 24 LT1963A Series PACKAGE DESCRIPTION ST Package 3-Lead Plastic SOT-223 (Reference LTC DWG # 05-08-1630) .248 – .264 (6.30 – 6.71) .114 – .124 (2.90 – 3.15) .059 MAX .129 MAX .264 – .287 (6.70 – 7.30) .130 – .146 (3.30 – 3.71) .248 BSC .039 MAX .059 MAX .090 BSC .181 MAX .0905 (2.30) BSC .071 (1.80) MAX .033 – .041 (0.84 – 1.04) RECOMMENDED SOLDER PAD LAYOUT 10° – 16° 10° MAX .010 – .014 (0.25 – 0.36) 10° – 16° .024 – .033 (0.60 – 0.84) .181 (4.60) BSC .012 (0.31) MIN .0008 – .0040 (0.0203 – 0.1016) ST3 (SOT-233) 0502 1963afd 25 LT1963A Series PACKAGE DESCRIPTION T Package 5-Lead Plastic TO-220 (Standard) (Reference LTC DWG # 05-08-1421) .390 – .415 (9.906 – 10.541) .147 – .155 (3.734 – 3.937) DIA .230 – .270 (5.842 – 6.858) .165 – .180 (4.191 – 4.572) .045 – .055 (1.143 – 1.397) .460 – .500 (11.684 – 12.700) .570 – .620 (14.478 – 15.748) .330 – .370 (8.382 – 9.398) .700 – .728 (17.78 – 18.491) .620 (15.75) TYP SEATING PLANE .152 – .202 .260 – .320 (3.861 – 5.131) (6.60 – 8.13) .095 – .115 (2.413 – 2.921) .155 – .195* (3.937 – 4.953) .013 – .023 (0.330 – 0.584) BSC .067 (1.70) .028 – .038 (0.711 – 0.965) .135 – .165 (3.429 – 4.191) * MEASURED AT THE SEATING PLANE T5 (TO-220) 0801 1963afd 26 LT1963A Series PACKAGE DESCRIPTION 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 1963afd 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. 27 LT1963A Series TYPICAL APPLICATION Adjustable Current Source R5 0.01Ω LT1963A-1.8 IN OUT SHDN GND FB LOAD VIN > 2.7V + C1 10μF R1 1k LT1004-1.2 R2 80.6k R4 2.2k R6 2.2k C3 1μF R8 100k R3 2k 2 + 1/2 LT1366 8 1 4 R7 470Ω 3 NOTE: ADJUST R1 FOR 0A TO 1.5A CONSTANT CURRENT C2 3.3μF – 1963A TA04 RELATED PARTS PART NUMBER LT1175 LT1185 LT1761 LT1762 LT1763 LT1764/ LT1764A LTC1844 LT1962 LT1964 LT1965 LT3020 LT3023 LT3024 LT3080/ LT3080-1 DESCRIPTION 500mA, Micropower, Negative LDO 3A, Negative LDO 100mA, Low Noise Micropower, LDO 150mA, Low Noise Micropower, LDO 500mA, Low Noise Micropower, LDO COMMENTS VIN: –20V to –4.3V, VOUT(MIN) = –3.8V, VDO = 0.50V, IQ = 45μA, ISD 10μA, DD, SOT-223, PDIP8 Packages VIN: –35V to –4.2V, VOUT(MIN) = –2.40V, VDO = 0.80V, IQ = 2.5mA, ISD