LT1963A Series 1.5A, Low Noise, Fast Transient Response LDO Regulators U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Optimized for Fast Transient Response Output Current: 1.5A Dropout Voltage: 340mV Low Noise: 40mVRMS (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 < 1mA Quiescent Current in Shutdown Stable with 10mF Output Capacitor Stable with Ceramic Capacitors Reverse Battery Protection No Reverse Current Thermal Limiting U APPLICATIO S ■ ■ 3.3V to 2.5V Logic Power Supplies Post Regulator for Switching Supplies 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 < 1mA 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 10mF. Small ceramic capacitors can be used without the necessary addition of ESR as is common with other regulators. Internal protection circuitry includes reverse battery protection, current limiting, thermal limiting and reverse current protection. The 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 and 8-lead SO packages. , LTC and LT are registered trademarks of Linear Technology Corporation. U TYPICAL APPLICATION Dropout Voltage 400 3.3V to 2.5V Regulator + VIN > 3V 10µF* OUT LT1963A-2.5 SHDN + 2.5V 1.5A 10µF* SENSE *TANTALUM, CERAMIC OR ALUMINUM ELECTROLYTIC GND 1963 TA01 DROPOUT VOLTAGE (mV) IN 350 300 250 200 150 100 50 0 0 0.2 0.4 0.6 0.8 1.0 1.2 OUTPUT CURRENT (A) 1.4 1.6 1963 TA02 1963af 1 LT1963A Series W W W AXI U U ABSOLUTE RATI GS (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 – 45∞C to 125∞C Storage Temperature Range ................. – 65∞C to 150∞C Lead Temperature (Soldering, 10 sec).................. 300∞C U U W PACKAGE/ORDER I FOR ATIO FRONT VIEW TAB IS GND 5 SENSE/ADJ* 4 OUT 3 GND 2 IN 1 SHDN Q PACKAGE 5-LEAD PLASTIC DD *PIN 5 = SENSE FOR LT1963A-1.8/LT1963A-2.5/LT1963A-3.3 = ADJ FOR LT1963A ORDER PART NUMBER LT1963AEQ LT1963AEQ-1.5 LT1963AEQ-1.8 LT1963AEQ-2.5 LT1963AEQ-3.3 TJMAX = 150∞C, qJA = 30∞C/ W FRONT VIEW TAB IS GND 5 SENSE/ADJ* 4 OUT 3 GND 2 IN 1 SHDN T PACKAGE 5-LEAD PLASTIC TO-220 *PIN 5 = SENSE FOR LT1963A-1.8/LT1963A-2.5/LT1963A-3.3 = ADJ FOR LT1963A TJMAX = 150∞C, qJA = 50∞C/ W ORDER PART NUMBER FRONT VIEW 3 TAB IS GND 2 1 OUT GND LT1963AEST-1.5 LT1963AEST-1.8 LT1963AEST-2.5 LT1963AEST-3.3 IN ST PACKAGE 3-LEAD PLASTIC SOT-223 TJMAX = 150∞C, qJA = 50∞C/ W ST PART MARKING 963A15 963A18 963A25 963A33 ORDER PART NUMBER LT1963AET LT1963AET-1.5 LT1963AET-1.8 LT1963AET-2.5 LT1963AET-3.3 ORDER PART NUMBER TOP VIEW OUT 1 8 IN SENSE/ADJ* 2 7 GND GND 3 6 GND NC 4 5 SHDN S8 PACKAGE 8-LEAD PLASTIC SO *PIN 2 = SENSE FOR LT1963A-1.8/LT1963A-2.5/LT1963A-3.3 = ADJ FOR LT1963A TJMAX = 150∞C, qJA = 70∞C/ W LT1963AES8 LT1963AES8-1.5 LT1963AES8-1.8 LT1963AES8-2.5 LT1963AES8-3.3 S8 PART MARKING 1963A 963A15 963A18 963A25 963A33 Consult LTC Marketing for parts specified with wider operating temperature ranges. 1963af 2 LT1963A Series ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25∞C. (Note 2) PARAMETER CONDITIONS Minimum Input Voltage (Notes 4,12) ILOAD = 0.5A ILOAD = 1.5A Regulated Output Voltage (Note 5) LT1963A-1.5 LT1963A-1.8 LT1963A-2.5 LT1963A-3.3 MIN ● V V 1.523 1.545 V V VIN = 2.3V, ILOAD = 1mA 2.8V < VIN < 20V, 1mA < ILOAD < 1.5A ● 1.773 1.737 1.800 1.800 1.827 1.854 V V VIN = 3V, ILOAD = 1mA 3.5V < VIN < 20V, 1mA < ILOAD < 1.5A ● 2.462 2.412 2.500 2.500 2.538 2.575 V V VIN = 3.8V, ILOAD = 1mA 4.3V < VIN < 20V, 1mA < ILOAD < 1.5A ● 3.250 3.200 3.300 3.300 3.350 3.400 V V VIN = 2.21V, ILOAD = 1mA 2.5V < VIN < 20V, 1mA < ILOAD < 1.5A ● 1.192 1.174 1.210 1.210 1.228 1.246 V V 2.0 2.5 3.0 3.5 1.5 6 7 10 10 5 mV mV mV mV mV 2 9 18 mV mV 2 10 20 mV mV 2.5 15 30 mV mV 3 20 35 mV mV 2 8 15 mV mV 0.02 0.06 0.10 V V 0.10 0.17 0.22 V V 0.19 0.27 0.35 V V 0.34 0.45 0.55 V V 1.0 1.1 3.8 15 80 1.5 1.6 5.5 25 120 mA mA mA mA mA DVIN = 2.21V to 20V, ILOAD = 1mA DVIN = 2.3V to 20V, ILOAD = 1mA DVIN = 3V to 20V, ILOAD = 1mA DVIN = 3.8V to 20V, ILOAD = 1mA DVIN = 2.21V to 20V, ILOAD = 1mA ● ● ● ● ● Load Regulation LT1963A-1.5 VIN = 2.5V, DILOAD = 1mA to 1.5A VIN = 2.5V, DILOAD = 1mA to 1.5A ● VIN = 2.8V, DILOAD = 1mA to 1.5A VIN = 2.8V, DILOAD = 1mA to 1.5A ● VIN = 3.5V, DILOAD = 1mA to 1.5A VIN = 3.5V, DILOAD = 1mA to 1.5A ● VIN = 4.3V, DILOAD = 1mA to 1.5A VIN = 4.3V, DILOAD = 1mA to 1.5A ● LT1963A (Note 4) VIN = 2.5V, DILOAD = 1mA to 1.5A VIN = 2.5V, DILOAD = 1mA to 1.5A ● 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 ● ● ● ● ● Output Voltage Noise COUT = 10mF, ILOAD = 1.5A, BW = 10Hz to 100kHz ADJ Pin Bias Current (Notes 4, 9) Shutdown Threshold VOUT = Off to On VOUT = On to Off SHDN Pin Current (Note 10) 2.5 1.500 1.500 LT1963A-1.5 LT1963A-1.8 LT1963A-2.5 LT1963A-3.3 LT1963A (Note 4) Dropout Voltage VIN = VOUT(NOMINAL) (Notes 6, 7, 12) 1.9 2.1 1.477 1.447 Line Regulation LT1963A-3.3 UNITS ● LT1963A LT1963A-2.5 MAX VIN = 2.21V, ILOAD = 1mA 2.5V < VIN < 20V, 1mA < ILOAD < 1.5A ADJ Pin Voltage (Notes 4, 5) LT1963A-1.8 TYP ● ● 0.25 VSHDN = 0V VSHDN = 20V Quiescent Current in Shutdown VIN = 6V, VSHDN = 0V Ripple Rejection VIN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 0.75A Current Limit VIN = 7V, VOUT = 0V VIN = VOUT(NOMINAL) + 1V, DVOUT = – 0.1V mVRMS 40 55 ● 1.6 3 10 mA 0.90 0.75 2 V V 0.01 3 1 30 mA mA 0.01 1 mA 63 dB 2 A A 1963af 3 LT1963A Series ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25∞C. (Note 2) PARAMETER CONDITIONS MIN Input Reverse Leakage Current (Note 13) Q, T, S8 Packages VIN = – 20V, VOUT = 0V ST Package VIN = – 20V, VOUT = 0V Reverse Output Current (Note 11) LT1963A-1.5 LT1963A-1.8 LT1963A-2.5 LT1963A-3.3 LT1963A (Note 4) TYP ● ● 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 Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. 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 ª TA. The LT1963A 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. 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 MAX 600 600 600 600 300 UNITS 1 2 mA mA 1200 1200 1200 1200 600 mA mA mA mA mA external resistor divider (two 4.12k resistors) for an output voltage of 2.4V. The external resistor divider will add a 300mA 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. U W TYPICAL PERFOR A CE CHARACTERISTICS Typical Dropout Voltage Guaranteed Dropout Voltage GUARANTEED DROPOUT VOLTAGE (mV) 600 450 DROPOUT VOLTAGE (mV) 400 350 TJ = 125°C 300 250 TJ = 25°C 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 1963 • G01 Dropout Voltage 500 TEST POINTS 450 500 TJ ≤ 125°C DROPOUT VOLTAGE (mV) 500 400 TJ ≤ 25°C 300 200 400 350 300 IL = 1.5A 250 IL = 0.5A 200 150 IL = 100mA 100 100 50 0 0 0.2 0.4 0.6 0.8 1.0 1.2 OUTPUT CURRENT (A) 1.4 1.6 1963 • G02 0 –50 IL = 1mA –25 50 25 0 75 TEMPERATURE (°C) 100 125 1963 G03 1963af 4 LT1963A Series U W TYPICAL PERFOR A CE CHARACTERISTICS LT1963A-1.8 Output Voltage LT1963A-1.5 Output Voltage 1.84 1.54 1.2 1.53 1.83 1.52 1.82 1.0 0.8 LT1963A 0.6 0.4 VIN = 6V RL = ∞, IL = 0 VSHDN = VIN 0.2 0 – 50 – 25 50 25 75 0 TEMPERATURE (°C) 100 IL = 1mA IL = 1mA OUTPUT VOLTAGE (V) LT1963A-1.5/1.8/-2.5/-3.3 OUTPUT VOLTAGE (V) 1.51 1.50 1.49 1.77 0 50 75 25 TEMPERATURE (°C) 100 1.76 –50 –25 125 LT1963A-2.5 Output Voltage IL = 1mA 2.54 3.34 1.220 2.42 –50 –25 0 25 50 75 100 125 ADJ PIN VOLTAGE (V) 1.225 OUTPUT VOLTAGE (V) 3.36 2.44 3.32 3.30 3.28 1.195 3.22 –50 –25 0 25 50 75 100 125 QUIESCENT CURRENT (mA) 8 6 4 2 8 9 10 1963 G41 50 75 125 100 1963 G08 LT1963A-2.5 Quiescent Current 14 TJ = 25°C RL = ∞ VSHDN = VIN TJ = 25°C RL = ∞ VSHDN = VIN 12 10 8 6 4 10 8 6 4 2 2 0 25 TEMPERATURE (°C) LT1963A-1.8 Quiescent Current 12 7 3 4 5 6 INPUT VOLTAGE (V) 0 1963 G07 14 10 2 1.190 –50 –25 TEMPERATURE (°C) TJ = 25°C RL = ∞ VSHDN = VIN 1 1.205 3.24 LT1963A-1.5 Quiescent Current 0 1.210 1.200 1963 G06 12 1.215 3.26 TEMPERATURE (°C) 14 125 100 LT1963A ADJ Pin Voltage IL = 1mA IL = 1mA 2.46 75 1.230 2.56 2.48 50 1963 G05 LT1963A-3.3 Output Voltage 2.50 25 TEMPERATURE (°C) 3.38 2.52 0 1963 G40 2.58 OUTPUT VOLTAGE (V) 1.79 1.47 1963 G04 QUIESCENT CURRENT (mA) 1.80 1.78 1.46 – 50 – 25 125 1.81 1.48 QUIESCENT CURRENT (mA) QUIESCENT CURRENT (mA) Quiescent Current 1.4 0 0 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1963 G09 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1963 G10 1963af 5 LT1963A Series U W TYPICAL PERFOR A CE CHARACTERISTICS 10 8 6 4 12 20 10 8 6 4 0 0 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 0 10 2 4 15 RL = 150, IL = 10mA* 10 RL = 5, IL = 300mA* 5 RL = 15, IL = 100mA* LT1963A-1.8 GND Pin Current 5 15 10 RL = 25, IL = 100mA* RL = 180, IL = 10mA* 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 0 9 10 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 LT1963A GND Pin Current 100 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.21V RL = 4.33, IL = 300mA* 6 4 RL = 12.1, IL = 100mA* 2 80 0 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1963 G16 RL = 330, IL = 100mA* 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 60 RL = 1, IL = 1.5A* 50 RL = 1.5, IL = 1A* 40 30 RL = 3, IL = 500mA* 100 80 70 50 40 30 8 RL = 1.8, IL = 1A* 20 0 3 4 5 6 7 INPUT VOLTAGE (V) RL = 1.2, IL = 1.5A* 60 10 2 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.8V 90 0 1 10 1963 G15 10 0 9 LT1963A-1.8 GND Pin Current 70 20 RL = 121, IL = 10mA* RL = 33, IL = 100mA* 0 10 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.5V 90 GND PIN CURRENT (mA) 8 9 LT1963A-1.5 GND Pin Current 10 10 RL = 11, IL = 300mA* 10 1963 G14 1963 G13 9 15 5 RL = 250, IL = 10mA* 0 0 1 8 TJ = 25°C VSHDN = VIN *FOR VOUT = 3.3V 20 RL = 8.33, IL = 300mA* 5 RL = 18, IL = 100mA* 0 3 4 5 6 7 INPUT VOLTAGE (V) LT1963A-3.3 GND Pin Current GND PIN CURRENT (mA) GND PIN CURRENT (mA) RL = 6, IL = 300mA* 2 25 TJ = 25°C VSHDN = VIN *FOR VOUT = 2.5V 20 15 1 1963 G42 LT1963A-2.5 GND Pin Current 25 TJ = 25°C VSHDN = VIN 20 *FOR VOUT = 1.8V 0 1963 G12 25 10 0 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 1963 G11 GND PIN CURRENT (mA) TJ = 25°C VSHDN = VIN *FOR VOUT = 1.5V 2 2 GND PIN CURRENT (mA) 25 TJ = 25°C RL = 4.3k VSHDN = VIN GND PIN CURRENT (mA) QUIESCENT CURRENT (mA) 12 14 GND PIN CURRENT (mA) TJ = 25°C RL = ∞ VSHDN = VIN QUIESCENT CURRENT (mA) 14 LT1963A-1.5 GND Pin Current LT1963A Quiescent Current LT1963A-3.3 Quiescent Current 9 10 1963 G43 RL = 3.6, IL = 500mA* 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1963 G17 1963af 6 LT1963A Series U W TYPICAL PERFOR A CE CHARACTERISTICS LT1963A-2.5 GND Pin Current 70 RL = 1.67, IL = 1.5A* 60 50 40 RL = 2.5, IL = 1A* 30 TJ = 25°C VSHDN = VIN *FOR VOUT = 3.3V 90 GND PIN CURRENT (mA) GND PIN CURRENT (mA) 80 80 70 RL = 2.2, IL = 1.5A* 60 50 40 RL = 3.3, IL = 1A* 30 RL = 5, IL = 500mA* 10 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 1 2 3 4 5 6 7 INPUT VOLTAGE (V) GND Pin Current vs ILOAD 0.9 80 SHDN PIN THRESHOLD (V) GND PIN CURRENT (mA) 8 9 70 60 50 40 30 20 10 1.4 1.6 0.9 0.7 0.6 0.5 0.4 0.3 0.2 –25 50 25 0 75 TEMPERATURE (°C) 100 1.0 0 2 4 0.7 0.6 6 8 10 12 14 16 18 20 SHDN PIN VOLTAGE (V) 1963 G24 IL = 1mA 0.5 0.4 0.3 0.2 –25 50 25 0 75 TEMPERATURE (°C) 125 1963 G23 5.0 VSHDN = 20V 4.5 6 5 4 3 2 1 0 –50 –25 100 ADJ Pin Bias Current 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.5 0 10 IL = 1.5A 0 –50 125 ADJ PIN BIAS CURRENT (µA) SHDN PIN INPUT CURRENT (µA) 4.5 1.5 9 0.8 SHDN Pin Input Current 2.0 8 0.1 7 2.5 3 4 5 6 7 INPUT VOLTAGE (V) SHDN Pin Threshold (Off-to-On) 0.8 SHDN Pin Input Current 3.0 2 1963 G22 5.0 3.5 1 1963 G20 IL = 1mA 1963 G21 4.0 RL = 2.42, IL = 500mA* 1.0 0 –50 0 0.4 0.6 0.8 1.0 1.2 OUTPUT CURRENT (A) RL = 1.21, IL = 1A* 0 0.1 0.2 30 10 SHDN PIN THRESHOLD (V) VIN = VOUT (NOMINAL) +1V 0 40 SHDN Pin Threshold (On-to-Off) 1.0 90 RL = 0.81, IL = 1.5A* 50 1963 G19 1963 G18 100 60 0 0 10 70 10 RL = 6.6, IL = 500mA* 0 0 80 20 10 0 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.21V 90 20 20 SHDN PIN INPUT CURRENT (µA) 100 GND PIN CURRENT (mA) TJ = 25°C VSHDN = VIN *FOR VOUT = 2.5V 90 LT1963A GND Pin Current LT1963A-3.3 GND Pin Current 100 100 50 25 75 0 TEMPERATURE (°C) 100 125 1963 G25 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 1963 G26 1963af 7 LT1963A Series U W TYPICAL PERFOR A CE CHARACTERISTICS Current Limit Current Limit 4.0 3.0 VIN = 7V 3.5 VOUT = 0V 3.0 TJ = 25°C 2.0 CURRENT LIMIT (A) CURRENT LIMIT (A) 2.5 TJ = – 50°C TJ = 125°C 1.5 1.0 2.5 2.0 1.5 1.0 0.5 0.5 ∆VOUT = 100mV 0 0 2 0 –50 6 8 10 12 14 16 18 20 4 INPUT/OUTPUT DIFFERENTIAL (V) 50 25 0 75 TEMPERATURE (°C) –25 100 1963 G27 1963 G28 Reverse Output Current Reverse Output Current 1.0 4.5 REVERSE OUTPUT CURRENT (mA) REVERSE OUTPUT CURRENT (mA) 5.0 LT1963A-1.8 4.0 LT1963A-1.5 3.5 3.0 LT1963A 2.5 2.0 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) 1.5 1.0 0.5 0 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE (V) 9 VIN = 0V 0.9 VOUT = 1.21V (LT1963A) = 1.5V (LT1963A-1.5) V 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 LT1963A 0.3 0.2 0.1 0 –50 10 50 25 0 75 TEMPERATURE (°C) –25 Ripple Rejection 70 74 50 40 20 COUT = 100µF TANTALUM +10 1µF CERAMIC COUT = 10µF TANTALUM 10 IL = 0.75A VIN = VOUT(NOMINAL) +1V + 50mVRMS RIPPLE 0 10 1k 10k 1M 100 100k FREQUENCY (Hz) 1963 G31 125 LT1963A Minimum Input Voltage 3.0 MINIMUM INPUT VOLTAGE (V) 76 RIPPLE REJECTION (dB) RIPPLE REJECTION (dB) Ripple Rejection 80 60 100 1963 G30 1963 G29 30 125 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) 125 1963 G32 2.5 IL = 1.5A IL = 500mA 2.0 1.5 IL = 100mA 1.0 0.5 0 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 1963 G33 1963af 8 LT1963A Series U W TYPICAL PERFOR A CE CHARACTERISTICS Load Regulation Output Noise Spectral Density LOAD REGULATION (mV) 5 OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) 10 LT1963A-1.5 0 LT1963A LT1963A-1.8 –5 LT1963A-2.5 LT1963A-3.3 –10 VIN = VOUT(NOMINAL) +1V (LT1963A-1.8/-2.5/-3.3) VIN = 2.7V (LT1963A/LT1963A-1.5) ∆IL = 1mA TO 1.5A –15 – 20 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 1.0 COUT = 10µF IL =1.5A LT1963A-2.5 LT1963A-3.3 0.1 LT1963A-1.8 LT1963A-1.5 0.01 10 100 1k 10k FREQUENCY (Hz) RMS Output Noise vs Load Current (10Hz to 100kHz) OUTPUT NOISE VOLTAGE (µVRMS) 100k 1963 G35 1963 G34 50 LT1963A LT1963A-3.3 10Hz to 100kHz Output Noise COUT = 10µF 45 40 LT1963A-3.3 35 LT1963A-2.5 30 25 VOUT 100µV/DIV LT1963A-1.8 20 LT1963A-1.5 15 LT1963A 10 5 0 0.0001 0.001 0.01 0.1 LOAD CURRENT (A) 10 1 COUT = 10µF ILOAD = 1.5A 1963 G37 1ms/DIV 1063 G36 LT1963A-3.3 Transient Response LT1963A-3.3 Transient Response 150 VIN = 4.3V 150 CIN = 3.3µF TANTALUM COUT = 10µF TANTALUM 100 OUTPUT VOLTAGE DEVIATION (mV) OUTPUT VOLTAGE DEVIATION (mV) 200 50 0 –50 100 50 0 –50 –100 0.6 1.5 LOAD CURRENT (A) –150 LOAD CURRENT (A) –100 0.4 0.2 0 0 2 4 6 8 10 12 14 16 18 20 TIME (µs) 1963 G38 VIN = 4.3V CIN = 33µF TANTALUM COUT = 100µF TANTALUM +10 1µF CERAMIC 1.0 0.5 0 0 50 100 150 200 250 300 350 400 450 500 TIME (µs) 1963 G39 1963af 9 LT1963A Series U U U PI FU CTIO S OUT: Output. The output supplies power to the load. A minimum output capacitor of 10mF 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 600mA 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 3mA 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 opencollector logic with a pull-up resistor. The pull-up resistor is required to supply the pull-up current of the opencollector gate, normally several microamperes, and the SHDN pin current, typically 3mA. 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 1mF to 10mF 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 + VIN SHDN RP + SENSE LOAD GND RP 1963 F01 Figure 1. Kelvin Sense Connection 1963af 10 LT1963A Series U W U U APPLICATIO S I FOR ATIO 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 1mA in shutdown. In addition to the low quiescent current, the LT1963A regulators incorporate several protection features which make them ideal for use in batterypowered 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, 3mA 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 Capacitance and Transient Response The LT1963A regulators are 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 10mF with an ESR of 3W or less is recommended to prevent oscillations. Larger values of output capacitance can decrease the peak deviations and provide improved transient response for larger load current changes. Bypass capacitors, used to decouple individual components powered by the LT1963A, 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 over temperature and applied voltage. The most common dielectrics used are Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high capacitances in a small package, but exhibit strong voltage and temperature coefficients as shown in Figures 3 and 4. When used with a 5V regulator, a 10mF Y5V capacitor can exhibit 20 OUT VIN LT1963A VOUT R2 + ADJ GND R1 1963 F02 Ê R2ˆ VOUT = 1.21V Á 1 + ˜ + (IADJ )(R2) Ë R1¯ VADJ = 1.21V IADJ = 3mA AT 25∞C OUTPUT RANGE = 1.21V TO 20V Figure 2. Adjustable Operation CHANGE IN VALUE (%) IN BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF 0 X5R –20 –40 –60 Y5V –80 –100 0 2 4 8 6 10 12 DC BIAS VOLTAGE (V) 14 16 1963 F03 Figure 3. Ceramic Capacitor DC Bias Characteristics 1963af 11 LT1963A Series U W U U APPLICATIO S I FOR ATIO 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. 40 CHANGE IN VALUE (%) 20 X5R 0 –20 –40 Y5V –60 –80 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF –100 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 1963 F04 Figure 4. Ceramic Capacitor Temperature Characteristics an effective value as low as 1mF to 2mF 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. 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 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 short-circuit 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 14mVRMS for the LT1963A increasing to 38mVRMS for the LT1963A-3.3. Higher values of output voltage noise may be measured when care is not exercised with regards 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 1963af 12 LT1963A Series U W U U APPLICATIO S I FOR ATIO 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. 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 1. Q Package, 5-Lead DD COPPER AREA TOPSIDE* BACKSIDE BOARD AREA THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 2500mm2 2500mm2 2500mm2 23∞C/W 1000mm2 2500mm2 2500mm2 25∞C/W 2 2 33∞C/W 125mm 2 2500mm 2500mm *Device is mounted on topside Table 2. SO-8 Package, 8-Lead SO COPPER AREA TOPSIDE* BACKSIDE BOARD AREA THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 2500mm2 2500mm2 2500mm2 55∞C/W 1000mm2 2500mm2 2500mm2 55∞C/W 2 2 2500mm 63∞C/W 2500mm2 69∞C/W 225mm 2 100mm2 2500mm 2500mm2 Table 3. SOT-223 Package, 3-Lead SOT-223 COPPER AREA TOPSIDE* BACKSIDE BOARD AREA THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 2500mm2 2500mm2 2500mm2 42∞C/W 2 2 2 42∞C/W 2500mm 2 2500mm 50∞C/W 2500mm2 2500mm2 56∞C/W 2 2 49∞C/W 2 52∞C/W 1000mm 225mm 2 100mm2 2 1000mm 2 1000mm 2500mm 2 1000mm 0mm 2 2500mm 1000mm 1000mm *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? 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 *Device is mounted on topside. 1963af 13 LT1963A Series U W U U APPLICATIO S I FOR ATIO 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 100mA) 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. 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 600mA. 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 5. 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 2mA. 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 REVERSE OUTPUT CURRENT (mA) Protection Features LT1963A VOUT = VADJ 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 3 4 5 6 7 8 OUTPUT VOLTAGE (V) 9 10 1963 F05 Figure 5. Reverse Output Current 1963af 14 LT1963A Series U TYPICAL APPLICATIO S SCR Pre-Regulator Provides Efficiency Over Line Variations L1 500µH L2 LT1963A-3.3 IN OUT 1N4148 10VAC AT 115VIN + SHDN GND 10000µF 1k 90-140 VAC FB 3.3VOUT 1.5A + 22µF 34k* 10VAC AT 115VIN 1N4002 12.1k* +V 2.4k C1A + 1/2 LT1018 750Ω 200k 1N4148 – 0.1µF +V C1B 0.033µF 750Ω +V + 1/2 LT1018 A1 1N4148 – LT1006 – 1N4002 TO ALL “+V” POINTS + 22µF + 1N4002 “SYNC” 10k 10k 10k +V 1µF +V L1 = COILTRONICS CTX500-2-52 L2 = STANCOR P-8559 * = 1% FILM RESISTOR = NTE5437 LT1004 1.2V 1963 TA03 1963af 15 LT1963A Series U PACKAGE DESCRIPTIO Q Package 5-Lead Plastic DD Pak (Reference LTC DWG # 05-08-1461) 0.256 (6.502) 0.060 (1.524) 0.060 (1.524) TYP 0.390 – 0.415 (9.906 – 10.541) 0.165 – 0.180 (4.191 – 4.572) 15° TYP 0.060 (1.524) 0.183 (4.648) 0.059 (1.499) TYP 0.330 – 0.370 (8.382 – 9.398) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK ( +0.008 0.004 –0.004 +0.203 0.102 –0.102 ) 0.095 – 0.115 (2.413 – 2.921) 0.075 (1.905) 0.300 (7.620) 0.045 – 0.055 (1.143 – 1.397) ( +0.012 0.143 –0.020 +0.305 3.632 –0.508 ) 0.067 (1.70) 0.028 – 0.038 BSC (0.711 – 0.965) 0.013 – 0.023 (0.330 – 0.584) 0.050 ± 0.012 (1.270 ± 0.305) Q(DD5) 1098 1963af 16 LT1963A Series U PACKAGE DESCRIPTIO S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) 0.189 – 0.197* (4.801 – 5.004) 8 7 6 5 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) 1 0.010 – 0.020 ¥ 45∞ (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.053 – 0.069 (1.346 – 1.752) 0°– 8° TYP 0.016 – 0.050 (0.406 – 1.270) 0.014 – 0.019 (0.355 – 0.483) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 2 3 4 0.004 – 0.010 (0.101 – 0.254) 0.050 (1.270) BSC SO8 1298 1963af 17 LT1963A Series U PACKAGE DESCRIPTIO ST Package 3-Lead Plastic SOT-223 (Reference LTC DWG # 05-08-1630) 0.248 – 0.264 (6.30 – 6.71) 0.114 – 0.124 (2.90 – 3.15) 0.264 – 0.287 (6.70 – 7.30) 0.130 – 0.146 (3.30 – 3.71) 0.033 – 0.041 (0.84 – 1.04) 0.0905 (2.30) NOM 10° – 16° 0.010 – 0.014 (0.25 – 0.36) 10° MAX 0.071 (1.80) MAX 10° – 16° 0.024 – 0.033 (0.60 – 0.84) 0.181 (4.60) NOM 0.012 (0.31) MIN 0.0008 – 0.0040 (0.0203 – 0.1016) ST3 (SOT-233) 1298 1963af 18 LT1963A Series U PACKAGE DESCRIPTIO T Package 5-Lead Plastic TO-220 (Standard) (Reference LTC DWG # 05-08-1421) 0.390 – 0.415 (9.906 – 10.541) 0.165 – 0.180 (4.191 – 4.572) 0.147 – 0.155 (3.734 – 3.937) DIA 0.045 – 0.055 (1.143 – 1.397) 0.230 – 0.270 (5.842 – 6.858) 0.460 – 0.500 (11.684 – 12.700) 0.570 – 0.620 (14.478 – 15.748) 0.330 – 0.370 (8.382 – 9.398) 0.620 (15.75) TYP 0.700 – 0.728 (17.78 – 18.491) SEATING PLANE 0.152 – 0.202 0.260 – 0.320 (3.861 – 5.131) (6.60 – 8.13) 0.095 – 0.115 (2.413 – 2.921) 0.155 – 0.195* (3.937 – 4.953) 0.013 – 0.023 (0.330 – 0.584) BSC 0.067 (1.70) 0.028 – 0.038 (0.711 – 0.965) 0.135 – 0.165 (3.429 – 4.191) * MEASURED AT THE SEATING PLANE T5 (TO-220) 0399 1963af 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. 19 LT1963A Series U TYPICAL APPLICATIO S Adjustable Current Source R1 0.01Ω R5 0.01Ω VIN > 2.7V C1 10µF + R1 1k LT1004-1.2 R2 80.6k Paralleling of Regulators for Higher Output Current LT1963A-1.8 IN OUT SHDN GND R4 2.2k R6 2.2k + LOAD VIN > 3.7V FB LT1963A-3.3 IN OUT C1 100µF SHDN GND C3 1µF R2 0.01Ω IN 3 NOTE: ADJUST R1 FOR 0A TO 1.5A CONSTANT CURRENT C2 3.3µF – R6 6.65k SHDN 1 1/2 LT1366 LT1963A OUT R7 470Ω 8 + FB R8 100k R3 2k 2 3.3V 3A C2 22µF + SHDN GND FB R7 4.12k 4 1963 TA04 R3 2.2k R4 2.2k R5 1k 3 2 8 + 1/2 LT1366 – 4 1 C3 0.01µF 1963 TA05 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1120 125mA Low Dropout Regulator with 20mA IQ Includes 2.5V Reference and Comparator LT1121 150mA Micropower Low Dropout Regulator 30mA IQ, SOT-223 Package LT1129 700mA Micropower Low Dropout Regulator 50mA Quiescent Current LT1175 500mA Negative Low Dropout Micropower Regulator 45mA IQ, 0.26V Dropout Voltage, SOT-223 Package LT1521 300mA Low Dropout Micropower Regulator with Shutdown 15mA IQ, Reverse Battery Protection LT1529 3A Low Dropout Regulator with 50mA IQ 500mV Dropout Voltage LT1772 Constant Frequency, Current Mode Step-Down DC/DC Controller Up to 94% Efficiency, SOT-23 Package, 100% Duty Cycle LTC1627 High Efficiency Synchronous Step-Down Switching Regulator Burst ModeTM Operation, Monolithic, 100% Duty Cycle LT1761 Series 100mA, Low Noise, Low Dropout Micropower Regulators in SOT-23 20mA Quiescent Current, 20mVRMS Noise, ThinSOTTM Package LT1762 Series 150mA, Low Noise, LDO Micropower Regulators 25mA Quiescent Current, 20mVRMS Noise, MSOP Package LT1763 Series 500mA, Low Noise, LDO Micropower Regulators 30mA Quiescent Current, 20mVRMS Noise, SO-8 Package LT1764A Series 3A, Fast Transient Response Low Dropout Regulator 340mV Dropout Voltage, 40mVRMS Noise LT1962 Series 300mA, Low Noise, LDO Micropower Regulator 30mA Quiescent Current, 20mVRMS Noise, MSOP Package LT1964 200mA, Low Noise, Negative LDO Micropower Regulator 30mA Quiescent Current, 30mVRMS Noise, ThinSOT Package Burst Mode is a registered trademark of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. 1963af 20 Linear Technology Corporation LT/TP 0602 2K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com „ LINEAR TECHNOLOGY CORPORATION 2002