LT1763 Series 500mA, Low Noise, LDO Micropower Regulators U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Low Noise: 20µVRMS (10Hz to 100kHz) Output Current: 500mA Low Quiescent Current: 30µA Wide Input Voltage Range: 1.8V to 20V Low Dropout Voltage: 300mV Very Low Shutdown Current: < 1µA No Protection Diodes Needed Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3V, 3.3V, 5V Adjustable Output from 1.22V to 20V Stable with 3.3µF Output Capacitor Stable with Aluminum, Tantalum or Ceramic Capacitors Reverse Battery Protection No Reverse Current Overcurrent and Overtemperature Protected 8-Lead SO Package U APPLICATIO S ■ ■ ■ Cellular Phones Battery-Powered Systems Noise-Sensitive Instrumentation Systems The LT ®1763 series are micropower, low noise, low dropout regulators. The devices are capable of supplying 500mA of output current with a dropout voltage of 300mV. Designed for use in battery-powered systems, the low 30µA quiescent current makes them an ideal choice. Quiescent current is well controlled; it does not rise in dropout as it does with many other regulators. A key feature of the LT1763 regulators is low output noise. With the addition of an external 0.01µF bypass capacitor, output noise drops to 20µVRMS over a 10Hz to 100kHz bandwidth. The LT1763 regulators are stable with output capacitors as low as 3.3µF. Small ceramic capacitors can be used without the series resistance required by other regulators. Internal protection circuitry includes reverse battery protection, current limiting, thermal limiting and reverse current protection. The parts come in fixed output voltages of 1.5V, 1.8V, 2.5V, 3V, 3.3V and 5V, and as an adjustable device with a 1.22V reference voltage. The LT1763 regulators are available in the 8-lead SO package. , LTC and LT are registered trademarks of Linear Technology Corporation. U TYPICAL APPLICATIO Dropout Voltage 400 3.3V Low Noise Regulator VIN 3.7V TO 20V IN 1µF OUT + SENSE LT1763-3.3 SHDN BYP GND 3.3V AT 500mA 20µVRMS NOISE 10µF 0.01µF 1763 TA01 DROPOUT VOLTAGE (mV) 350 300 250 200 150 100 50 0 0 100 300 400 200 OUTPUT CURRENT (mA) 500 1763 TA02 1763fa 1 LT1763 Series U W U W W U W ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) IN Pin Voltage ........................................................ ±20V OUT Pin Voltage .................................................... ±20V Input to Output Differential Voltage ....................... ±20V SENSE Pin Voltage ............................................... ±20V ADJ Pin Voltage ...................................................... ±7V BYP Pin Voltage.................................................... ±0.6V SHDN Pin Voltage ................................................. ±20V Output Short-Circut Duration .......................... Indefinite Operating Junction Temperature Range (Note 2) ............................................ – 40°C to 125°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C TOP VIEW OUT 1 8 IN SENSE/ADJ* 2 7 GND GND 3 6 GND BYP 4 5 SHDN *PIN 2: SENSE FOR LT1763-1.5/ LT1763-1.8/LT1763-2.5/ LT1763-3/LT1763-3.3/LT1763-5 ADJ FOR LT1763 TJMAX = 150°C, θJA = 70°C/ W, θJC = 35°C/ W SEE THE APPLICATIONS INFORMATION SECTION. S8 PACKAGE 8-LEAD PLASTIC SO ORDER PART NUMBER S8 PART MARKING LT1763CS8 LT1763CS8-3 LT1763CS8-1.5 LT1763CS8-3.3 LT1763CS8-1.8 LT1763CS8-5 LT1763CS8-2.5 1763 17633 176315 176333 176318 17635 176325 Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) PARAMETER CONDITIONS Minimum Operating Voltage ILOAD = 500mA (Notes 3, 11) ● Regulated Output Voltage (Note 4) LT1763-1.5 VIN = 2V, ILOAD = 1mA 2.5V < VIN < 20V, 1mA < ILOAD < 500mA ● LT1763-1.8 VIN = 2.3V, ILOAD = 1mA 2.8V < VIN < 20V, 1mA < ILOAD < 500mA LT1763-2.5 VIN = 3V, ILOAD = 1mA 3.5V < VIN < 20V, 1mA < ILOAD < 500mA LT1763-3 MIN TYP MAX UNITS 1.8 2.3 V 1.485 1.462 1.5 1.5 1.515 1.538 V V ● 1.782 1.755 1.8 1.8 1.818 1.845 V V ● 2.475 2.435 2.5 2.5 2.525 2.565 V V ● 2.970 2.925 3 3 3.030 3.075 V V ● 3.267 3.220 3.3 3.3 3.333 3.380 V V VIN = 5.5V, ILOAD = 1mA 6V < VIN < 20V, 1mA < ILOAD < 500mA ● 4.950 4.875 5 5 5.050 5.125 V V VIN = 2V, ILOAD = 1mA 2.22V < VIN < 20V, 1mA < ILOAD < 500mA ● 1.208 1.190 1.22 1.22 1.232 1.250 V V 1 1 1 1 1 1 1 5 5 5 5 5 5 5 mV mV mV mV mV mV mV 3 8 15 mV mV 4 9 18 mV mV 5 12 25 mV mV VIN = 3.5V, ILOAD = 1mA 4V < VIN < 20V, 1mA < ILOAD < 500mA LT1763-3.3 VIN = 3.8V, ILOAD = 1mA 4.3V < VIN < 20V, 1mA < ILOAD < 500mA LT1763-5 ADJ Pin Voltage (Notes 3, 4) LT1763 Line Regulation LT1763-1.5 LT1763-1.8 LT1763-2.5 LT1763-3 LT1763-3.3 LT1763-5 LT1763 (Note 3) ∆VIN = 2V to 20V, ILOAD = 1mA ∆VIN = 2.3V to 20V, ILOAD = 1mA ∆VIN = 3V to 20V, ILOAD = 1mA ∆VIN = 3.5V to 20V, ILOAD = 1mA ∆VIN = 3.8V to 20V, ILOAD = 1mA ∆VIN = 5.5V to 20V, ILOAD = 1mA ∆VIN = 2V to 20V, ILOAD = 1mA ● ● ● ● ● ● ● Load Regulation LT1763-1.5 VIN = 2.5V, ∆ILOAD = 1mA to 500mA VIN = 2.5V, ∆ILOAD = 1mA to 500mA ● VIN = 2.8V, ∆ILOAD = 1mA to 500mA VIN = 2.8V, ∆ILOAD = 1mA to 500mA ● VIN = 3.5V, ∆ILOAD = 1mA to 500mA VIN = 3.5V, ∆ILOAD = 1mA to 500mA ● LT1763-1.8 LT1763-2.5 1763fa 2 LT1763 Series ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) PARAMETER CONDITIONS Load Regulation LT1763-3 LT1763-3.3 LT1763-5 LT1763 (Note 3) MIN VIN = 4V, ∆ILOAD = 1mA to 500mA VIN = 4V, ∆ILOAD = 1mA to 500mA ● VIN = 4.3V, ∆ILOAD = 1mA to 500mA VIN = 4.3V, ∆ILOAD = 1mA to 500mA ● VIN = 6V, ∆ILOAD = 1mA to 500mA VIN = 6V, ∆ILOAD = 1mA to 500mA ● VIN = 2.3V, ∆ILOAD = 1mA to 500mA VIN = 2.3V, ∆ILOAD = 1mA to 500mA ● Dropout Voltage VIN = VOUT(NOMINAL) ILOAD = 10mA ILOAD = 10mA ● (Notes 5, 6, 11) ILOAD = 50mA ILOAD = 50mA ● ILOAD = 100mA ILOAD = 100mA ● ILOAD = 500mA ILOAD = 500mA ● GND Pin Current VIN = VOUT(NOMINAL) (Notes 5, 7) ILOAD = 0mA ILOAD = 1mA ILOAD = 50mA ILOAD = 100mA ILOAD = 250mA ILOAD = 500mA ● ● ● ● ● ● Output Voltage Noise COUT = 10µF, CBYP = 0.01µF, ILOAD = 500mA, BW = 10Hz to 100kHz ADJ Pin Bias Current (Notes 3, 8) Shutdown Threshold VOUT = Off to On VOUT = On to Off SHDN Pin Current (Note 9) TYP MAX 7 15 30 mV mV 7 17 33 mV mV 12 25 50 mV mV 2 6 12 mV mV 0.13 0.19 0.25 V V 0.17 0.22 0.32 V V 0.20 0.24 0.34 V V 0.30 0.35 0.45 V V 30 65 1.1 2 5 11 75 120 1.6 3 8 16 µA µA mA mA mA mA µVRMS 20 ● ● 0.25 VSHDN = 0V VSHDN = 20V 30 100 nA 0.8 0.65 2 V V µA µA 0.1 1 Quiescent Current in Shutdown VIN = 6V, VSHDN = 0V Ripple Rejection VIN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 500mA 0.1 Current Limit VIN = 7V, VOUT = 0V VIN = VOUT(NOMINAL) + 1V, ∆VOUT = – 0.1V ● Input Reverse Leakage Current VIN = – 20V, VOUT = 0V ● Reverse Output Current (Note 10) LT1763-1.5 LT1763-1.8 LT1763-2.5 LT1763-3 LT1763-3.3 LT1763-5 LT1763 (Note 3) VOUT = 1.5V, VIN < 1.5V VOUT = 1.8V, VIN < 1.8V VOUT = 2.5V, VIN < 2.5V VOUT = 3V, VIN < 3V VOUT = 3.3V, VIN < 3.3V VOUT = 5V, VIN < 5V VOUT = 1.22V, VIN < 1.22V Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1763 regulators are tested and specified under pulse load conditions such that TJ ≈ TA. The LT1763 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 3: The LT1763 (adjustable version) is tested and specified for these conditions with the ADJ pin connected to the OUT pin. Note 4: Operating conditions are limited by maximum junction temperature. The regulated output voltage specification will not apply for 50 UNITS 1 µA 65 dB 700 mA mA 520 10 10 10 10 10 10 5 1 mA 20 20 20 20 20 20 10 µA µA µA µA µA µA µA 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 5: To satisfy requirements for minimum input voltage, the LT1763 (adjustable version) is tested and specified for these conditions with an external resistor divider (two 250k resistors) for an output voltage of 2.44V. The external resistor divider will add a 5µA DC load on the output. 1763fa 3 LT1763 Series ELECTRICAL CHARACTERISTICS Note 6: 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 7: GND pin current is tested with VIN = VOUT(NOMINAL) or VIN = 2.3V (whichever is greater) and a current source load. This means the device is tested while operating in its dropout region. This is the worst-case GND pin current. The GND pin current will decrease slightly at higher input voltages. Note 8: ADJ pin bias current flows into the ADJ pin. Note 9: SHDN pin current flows into the SHDN pin. Note 10: 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 11: For the LT1763, LT1763-1.5 and LT1763-1.8 dropout voltage will be limited by the minimum input voltage specification under some output voltage/load conditions. See the curve of Minimum Input Voltage in the Typical Performance Characteristics. U W TYPICAL PERFORMANCE CHARACTERISTICS Typical Dropout Voltage TJ = 125°C 350 300 250 TJ = 25°C 200 150 100 50 0 = TEST POINTS 450 450 400 400 DROPOUT VOLTAGE (mV) GUARANTEED DROPOUT VOLTAGE (mV) 450 DROPOUT VOLTAGE (mV) 500 500 400 TJ ≤ 125°C 350 300 TJ ≤ 25°C 250 200 150 150 0 –50 –25 50 100 150 200 250 300 350 400 450 500 OUTPUT CURRENT (mA) OUTPUT VOLTAGE (V) 40 15 125 IL = 1mA 1.521 1.83 1.514 1.82 OUTPUT VOLTAGE (V) 45 100 1.84 IL = 1mA 20 50 25 0 75 TEMPERATURE (°C) LT1763-1.8 Output Voltage 1.528 50 25 IL = 50mA 1763 G03 LT1763-1.5 Output Voltage VSHDN = VIN IL = 1mA IL = 10mA 1763 G02 Quiescent Current QUIESCENT CURRENT (µA) 200 50 0 IL = 100mA 250 50 50 100 150 200 250 300 350 400 450 500 OUTPUT CURRENT (mA) IL = 500mA IL = 250mA 300 100 1763 G01 30 350 100 0 0 35 Dropout Voltage Guaranteed Dropout Voltage 500 1.507 1.500 1.493 1.486 1.81 1.80 1.79 1.78 10 VIN = 6V 5 RL = ∞, IL = 0 (LT1763-1.5/-1.8/-2.5/-3/-3.3/-5) RL = 250k, IL = 5µA (LT1763) 0 0 25 50 75 100 125 –50 –25 TEMPERATURE (°C) 1.77 1.479 1.472 –50 –25 0 25 50 75 100 125 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) 1763 G04 1.76 –50 –25 1763 G50 1763 G51 1763fa 4 LT1763 Series U W TYPICAL PERFORMANCE CHARACTERISTICS LT1763-2.5 Output Voltage 3.060 2.54 3.360 IL = 1mA IL = 1mA IL = 1mA 3.045 3.345 2.52 3.030 3.330 2.51 2.50 2.49 2.48 OUTPUT VOLTAGE (V) 2.53 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) LT1763-3.3 Output Voltage LT1763-3 Output Voltage 3.015 3.000 2.985 2.970 2.955 2.47 2.46 –50 –25 0 25 50 75 125 100 2.940 –50 –25 0 25 50 75 125 100 3.285 3.270 3.240 –50 –25 5.050 1.230 5.025 5.000 4.975 4.950 1.220 1.215 1.210 1.205 4.900 –50 –25 1.200 –50 –25 125 0 25 50 75 100 125 150 125 100 75 VSHDN = VIN VSHDN = VIN VSHDN = 0V 1 2 9 10 1763 G53 8 9 10 250 175 150 125 100 75 50 VSHDN = VIN 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 200 175 150 125 100 75 50 VSHDN = VIN 25 VSHDN = 0V 0 TJ = 25°C RL = ∞ 225 200 0 8 3 4 5 6 7 INPUT VOLTAGE (V) 1763 G52 TJ = 25°C RL = ∞ 25 VSHDN = 0V 3 4 5 6 7 INPUT VOLTAGE (V) 50 0 QUIESCENT CURRENT (µA) QUIESCENT CURRENT (µA) 175 2 75 LT1763-3 Quiescent Current 225 200 1 100 0 250 TJ = 25°C RL = ∞ 0 125 LT1763-2.5 Quiescent Current 250 0 150 1763 G09 LT1763-1.8 Quiescent Current 25 175 TEMPERATURE (°C) 1763 G08 50 200 25 TEMPERATURE (°C) 225 TJ = 25°C RL = ∞ 225 1.225 4.925 100 125 100 250 IL = 1mA QUIESCENT CURRENT (µA) 1.235 ADJ PIN VOLTAGE (V) 5.075 75 75 LT1763-1.5 Quiescent Current 1.240 IL = 1mA 50 50 1763 G07 LT1763 ADJ Pin Voltage 5.100 25 25 TEMPERATURE (°C) 1763 G06 LT1763-5 Output Voltage 0 0 TEMPERATURE (°C) 1763 G05 OUTPUT VOLTAGE (V) 3.300 3.255 TEMPERATURE (°C) QUIESCENT CURRENT (µA) 3.315 VSHDN = 0V 0 9 10 1763 G10 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1763 G11 1763fa 5 LT1763 Series U W TYPICAL PERFORMANCE CHARACTERISTICS LT1763-3.3 Quiescent Current 250 40 250 TJ = 25°C RL = ∞ 225 175 150 125 100 75 175 150 125 100 75 50 VSHDN = VIN 25 0 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 VSHDN = VIN 25 VSHDN = 0V 9 10 1 0 2 3 4 5 6 7 INPUT VOLTAGE (V) 1763 G12 RL = 1.5k IL = 1mA* 0 1 2 8 9 1000 RL = 36Ω IL = 50mA* 800 TJ = 25°C VIN = VSHDN *FOR VOUT = 1.8V 600 RL = 180Ω IL = 10mA* 400 0 10 RL = 1.8k IL = 1mA* 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 200 RL = 3k IL = 1mA* 0 1 2 200 RL = 2.5k IL = 1mA* 3 4 5 6 7 INPUT VOLTAGE (V) 9 10 1763 G16 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 LT1763-5 GND Pin Current 1000 RL = 66Ω IL = 50mA* 800 TJ = 25°C VIN = VSHDN *FOR VOUT = 3.3V 600 400 RL = 330Ω IL = 10mA* 200 RL = 3.3k IL = 1mA* 0 8 0 1763 G15 GND PIN CURRENT (µA) GND PIN CURRENT (µA) GND PIN CURRENT (µA) RL = 300Ω IL = 10mA* RL = 250Ω IL = 10mA* 1200 1000 TJ = 25°C VIN = VSHDN *FOR VOUT = 3V 400 400 10 1200 800 0 9 TJ = 25°C VIN = VSHDN *FOR VOUT = 2.5V 600 LT1763-3.3 GND Pin Current 1200 600 800 0 0 RL = 50Ω IL = 50mA* 1763 G55 LT1763-3 GND Pin Current RL = 60Ω IL = 50mA* 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) LT1763-2.5 GND Pin Current 1763 G54 1000 4 1200 200 3 4 5 6 7 INPUT VOLTAGE (V) 2 1763 G14 GND PIN CURRENT (µA) RL = 150Ω IL = 10mA* 200 0 TJ = 25°C VIN = VSHDN *FOR VOUT = 1.5V VSHDN = 0V 0 1000 GND PIN CURRENT (µA) GND PIN CURRENT (µA) 1000 400 10 10 1200 600 15 LT1763-1.8 GND Pin Current 1200 800 20 1763 G13 LT1763-1.5 GND Pin Current RL = 30Ω IL = 50mA* 25 0 9 8 VSHDN = VIN 30 5 VSHDN = 0V 0 TJ = 25°C RL = 250k 35 200 QUIESCENT CURRENT (µA) 200 50 TJ = 25°C RL = ∞ QUIESCENT CURRENT (µA) 225 QUIESCENT CURRENT (µA) LT1763 Quiescent Current LT1763-5 Quiescent Current 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) RL = 100Ω IL = 50mA* 800 TJ = 25°C VIN = VSHDN *FOR VOUT = 5V 600 RL = 500Ω IL = 10mA* 400 RL = 5k IL = 1mA* 200 8 9 10 1763 G17 0 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1763 G18 1763fa 6 LT1763 Series U W TYPICAL PERFORMANCE CHARACTERISTICS LT1763 GND Pin Current 12 10 RL = 24.4Ω IL = 50mA* GND PIN CURRENT (mA) 800 TJ = 25°C VIN = VSHDN *FOR VOUT = 1.22V 600 RL = 122Ω IL = 10mA* 400 RL = 1.22k IL = 1mA* 200 0 1 2 8 RL = 5Ω IL = 300mA* 6 4 RL = 15Ω IL = 100mA* 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 0 10 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 GND PIN CURRENT (mA) GND PIN CURRENT (mA) RL = 25Ω IL = 100mA* 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 RL = 10Ω IL = 300mA* 4 RL = 30Ω IL = 100mA* 2 10 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 RL = 10Ω IL = 500mA* 4 RL = 50Ω IL = 100mA* 2 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 1763 G23 RL = 11Ω IL = 300mA* RL = 33Ω IL = 100mA* 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1763 G22 GND Pin Current vs ILOAD VIN = VOUT(NOMINAL) + 1V 10 RL = 2.44Ω IL = 500mA* 8 RL = 4.07Ω IL = 300mA* 6 4 0 10 4 0 10 TJ = 25°C VIN = VSHDN *FOR VOUT = 1.22V RL = 12.2Ω IL = 100mA* 2 10 9 12 10 GND PIN CURRENT (mA) GND PIN CURRENT (mA) 9 6 2 12 RL = 16.7Ω IL = 300mA* 8 RL = 6.6Ω IL = 500mA* 1763 G21 12 6 3 4 5 6 7 INPUT VOLTAGE (V) TJ = 25°C VIN = VSHDN *FOR VOUT = 3.3V 8 LT1763 GND Pin Current 8 2 10 RL = 6Ω IL = 500mA* 6 LT1763-5 GND Pin Current 10 1 12 1763 G20 TJ = 25°C VIN = VSHDN *FOR VOUT = 5V 0 1763 G57 TJ = 25°C VIN = VSHDN *FOR VOUT = 3V 8 0 0 RL = 18Ω IL = 100mA* LT1763-3.3 GND Pin Current 10 RL = 8.33Ω IL = 300mA* 2 0 0 10 GND PIN CURRENT (mA) TJ = 25°C VIN = VSHDN *FOR VOUT = 2.5V 4 0 9 12 12 6 4 LT1763-3 GND Pin Current RL = 5Ω IL = 500mA* RL = 6Ω IL = 300mA* 6 1763 G56 LT1763-2.5 GND Pin Current 8 RL = 3.6Ω IL = 500mA* 8 2 1763 G19 10 TJ = 25°C VIN = VSHDN *FOR VOUT = 1.8V 10 RL = 3Ω IL = 500mA* GND PIN CURRENT (mA) GND PIN CURRENT (µA) 1000 12 TJ = 25°C VIN = VSHDN *FOR VOUT = 1.5V GND PIN CURRENT (mA) 1200 0 LT1763-1.8 GND Pin Current LT1763-1.5 GND Pin Current 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 8 6 4 2 10 1763 G24 0 0 50 100 150 200 250 300 350 400 450 500 OUTPUT CURRENT (mA) 1763 G25 1763fa 7 LT1763 Series U W TYPICAL PERFORMANCE CHARACTERISTICS SHDN Pin Threshold (On-to-Off) SHDN Pin Threshold (Off-to-On) 1.0 IL = 1mA 1.4 0.8 0.7 0.6 0.5 0.4 0.3 0.2 SHDN PIN INPUT CURRENT (µA) 0.9 SHDN PIN THRESHOLD (V) SHDN PIN THRESHOLD (V) 0.9 SHDN Pin Input Current 1.0 0.8 IL = 500mA 0.7 0.6 0.5 IL = 1mA 0.4 0.3 0.2 0.1 0.1 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 50 25 0 75 TEMPERATURE (°C) 100 0.8 0.6 0.4 100 80 60 40 100 0.5 0.4 0.3 0 125 Reverse Output Current 0.6 0.4 0.2 TJ = 25°C, VIN = 0V CURRENT FLOWS INTO OUTPUT PIN VOUT = VADJ (LT1763) 90 80 70 LT1763-1.5 50 LT1763-2.5 LT1763-3 40 LT1763-3.3 30 20 LT1763-5 1763 G32 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE (V) 9 VIN = 0V, VOUT = 1.22V (LT1763) 18 VOUT = 1.5V (LT1763-1.5) = 1.8V (LT1763-1.8) V 16 VOUT = 2.5V (LT1763-2.5) OUT 14 VOUT = 3V (LT1763-3) VOUT = 3.3V (LT1763-3.3) 12 VOUT = 5V (LT1763-5) 10 8 6 4 LT1763-1.5/-1.8/ -2.5/-3/-3.3/-5 LT1763 2 0 125 7 6 Reverse Output Current LT1763 LT1763-1.8 60 10 100 4 3 2 5 INPUT VOLTAGE (V) 20 REVERSE OUTPUT CURRENT (µA) 0.8 1 1763 G31 100 REVERSE OUTPUT CURRENT (µA) CURRENT LIMIT (A) 0.6 1763 G30 Current Limit 50 25 0 75 TEMPERATURE (°C) 0.7 0 50 25 0 75 TEMPERATURE (°C) 1763 G29 1.0 VOUT = 0V 0.1 TEMPERATURE (°C) 1.2 10 0.2 0 –50 –25 125 VIN = 7 VOUT = 0V 9 0.8 100 20 0.2 75 3 4 5 6 7 8 SHDN PIN VOLTAGE (V) Current Limit CURRENT LIMIT (A) ADJ PIN BIAS CURRENT (nA) SHDN PIN INPUT CURRENT (µA) 1.0 2 1.0 0.9 1.2 1 1763 G28 120 0 –50 –25 0.2 0 VSHDN = 20V 1.4 50 0.4 125 140 25 0.6 ADJ Pin Bias Current SHDN Pin Input Current 1.6 0 0.8 1763 G27 1763 G26 0 –50 –25 1.0 0 0 –50 –25 125 1.2 10 1763 G33 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 1763 G34 1763fa 8 LT1763 Series U W TYPICAL PERFORMANCE CHARACTERISTICS Input Ripple Rejection Ripple Rejection 68 70 70 CBYP = 0.01µF 66 60 64 60 COUT = 10µF 50 40 30 IL = 500mA VIN = VOUT(NOMINAL) + 1V + 50mVRMS RIPPLE CBYP = 0 20 10 50 CBYP = 1000pF CBYP = 100pF 40 30 20 IL = 500mA VIN = VOUT(NOMINAL) + 1V + 50mVRMS RIPPLE COUT = 10µF COUT = 4.7µF 10 0 RIPPLE REJECTION (dB) 80 RIPPLE REJECTION (dB) 58 100k 1k 10k FREQUENCY (Hz) 1M 10 100 100k 1k 10k FREQUENCY (Hz) LT1763-2.5 LT1763 LOAD REGULATION (mV) 1.25 1.00 0.75 0.50 LT1763-1.8 –5 LT1763-3 –10 LT1763-3.3 LT1763-5 –15 –20 0.25 VIN = VOUT(NOMINAL) + 1V ∆IL = 1mA TO 500mA VOUT = 1.22V 0 –50 –25 50 25 0 75 TEMPERATURE (°C) LT1763-1.5 0 IL = 500mA IL = 1mA 100 –25 –50 –25 125 0 25 50 75 100 CBYP = 0.01µF OUTPUT NOISE (µVRMS) 0.1 1k 10k FREQUENCY (Hz) LT1763 LT1763-2.5 LT1763-1.5 LT1763-1.8 0.1 COUT = 10µF IL = 500mA 100 100k LT1763-5 120 LT1763-3.3 100 LT1763-3 80 LT1763-2.5 60 40 LT1763 LT1763-1.8 LT1763-1.5 10 100 140 100k COUT = 10µF CBYP = 0 CBYP = 0.01µF 120 LT1763-5 100 80 60 LT1763 40 LT1763-5 20 LT1763 1000 10000 CBYP (pF) 1763 G41 1k 10k FREQUENCY (Hz) RMS Output Noise vs Load Current (10Hz to 100kHz) 0 100 1 160 20 0.01 10 LT1763-3.3 LT1763-5 1763 G40 COUT = 10µF IL = 500mA f = 10Hz TO 100kHz 140 LT1763 125 LT1763-3 0.01 10 125 160 COUT = 10µF IL = 500mA CBYP = 100pF 100 10 RMS Output Noise vs Bypass Capacitor 10 1 75 1763 G39 Output Noise Spectral Density CBYP = 1000pF 50 1763 G37 TEMPERATURE (°C) 1763 G38 LT1763-5 25 Output Noise Spectral Density CBYP = 0 5 2.25 1.75 0 TEMPERATURE (°C) Load Regulation 2.50 1.50 52 –50 –25 1M 1763 G36 LT1763 Minimum Input Voltage 2.00 VIN = VOUT (NOMINAL) + 1V + 0.5VP-P RIPPLE AT f = 120Hz IL = 500mA 56 OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) 100 1763 G35 MINIMUM INPUT VOLTAGE (V) 60 0 10 OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) 62 54 OUTPUT NOISE (µVRMS) RIPPLE REJECTION (dB) Input Ripple Rejection 80 1763 G42 0 0.01 0.1 10 100 1 LOAD CURRENT (mA) 1000 1763 G43 1763fa 9 LT1763 Series U W TYPICAL PERFORMANCE CHARACTERISTICS LT1763-5 10Hz to 100kHz Output Noise CBYP = 0 LT1763-5 10Hz to 100kHz Output Noise CBYP = 100pF LT1763-5 10Hz to 100kHz Output Noise CBYP = 1000pF VOUT 100µV/DIV VOUT 100µV/DIV VOUT 100µV/DIV 1ms/DIV 1ms/DIV 1763 G46 LT1763-5 10Hz to 100kHz Output Noise CBYP = 0.01µF COUT = 10µF IL = 500mA 1763 G47 1763 G45 VIN = 6V CIN = 10µF COUT = 10µF 0.4 0.2 0 –0.2 –0.4 600 400 200 0 0 200 1763 G44 LT1763-5 Transient Response CBYP = 0.01µF 400 600 TIME (µs) 800 VIN = 6V CIN = 10µF COUT = 10µF 0.10 0.05 0 –0.05 –0.10 LOAD CURRENT (mA) 1ms/DIV LOAD CURRENT (mA) OUTPUT VOLTAGE DEVIATION (V) LT1763-5 Transient Response CBYP = 0 VOUT 100µV/DIV COUT = 10µF IL = 500mA 1ms/DIV COUT = 10µF IL = 500mA OUTPUT VOLTAGE DEVIATION (V) COUT = 10µF IL = 500mA 600 400 200 0 1000 0 10 20 30 40 50 60 70 80 90 100 TIME (µs) 1763 G48 1763 G49 U U U PIN FUNCTIONS OUT (Pin 1): Output. The output supplies power to the load. A minimum output capacitor of 3.3µF is required to prevent oscillations. Larger output capacitors will be required for applications with large transient loads to limit peak voltage transients. See the Applications Information section for more information on output capacitance and reverse output characteristics. SENSE (Pin 2): Output Sense. For fixed voltage versions of the LT1763 (LT1763-1.5/LT1763-1.8/LT1763-2.5/ LT1763-3/LT1763-3.3/LT1763-5), 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). 8 IN OUT 1 RP LT1763 + VIN 5 SHDN SENSE GND + 2 LOAD 3 RP 1763 F01 Figure 1. Kelvin Sense Connection 1763fa 10 LT1763 Series U U U PIN FUNCTIONS 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 10µA 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 (Pin 2): Adjust. For the adjustable LT1763, this is the input to the error amplifier. This pin is internally clamped to ±7V. It has a bias current of 30nA which flows into the pin (see curve of ADJ Pin Bias Current vs Temperature in the Typical Performance Characteristics section). The ADJ pin voltage is 1.22V referenced to ground and the output voltage range is 1.22V to 20V. BYP (Pin 4): Bypass. The BYP pin is used to bypass the reference of the LT1763 regulators to achieve low noise performance from the regulator. The BYP pin is clamped internally to ±0.6V (one VBE). A small capacitor from the output to this pin will bypass the reference to lower the output voltage noise. A maximum value of 0.01µF can be used for reducing output voltage noise to a typical 20µVRMS over a 10Hz to 100kHz bandwidth. If not used, this pin must be left unconnected. GND (Pins 3, 6, 7): Ground. SHDN (Pin 5): Shutdown. The SHDN pin is used to put the LT1763 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 1µA. 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 (Pin 8): Input. Power is supplied to the device through the IN pin. A bypass capacitor is required on this pin if the device is more than six inches away from the main input filter capacitor. In general, the output impedance of a battery rises with frequency, so it is advisable to include a bypass capacitor in battery-powered circuits. A bypass capacitor in the range of 1µF to 10µF is sufficient. The LT1763 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. U W U U APPLICATIONS INFORMATION The LT1763 series are 500mA low dropout regulators with micropower quiescent current and shutdown. The devices are capable of supplying 500mA at a dropout voltage of 300mV. Output voltage noise can be lowered to 20µVRMS over a 10Hz to 100kHz bandwidth with the addition of a 0.01µF reference bypass capacitor. Additionally, the reference bypass capacitor will improve transient response of the regulator, lowering the settling time for transient load conditions. The low operating quiescent current (30µA) drops to less than 1µA in shutdown. In addition to the low quiescent current, the LT1763 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 LT1763-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 LT1763 has an output voltage range of 1.22V 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 ADJ pin voltage at 1.22V referenced to ground. The current in R1 is then equal to 1.22V/R1 and the current in R2 is the current in R1 1763fa 11 LT1763 Series U U W U APPLICATIONS INFORMATION OUT IN VIN VOUT + R2 LT1763 ADJ GND R1 R2 VOUT = 1.22V 1 + + (IADJ )(R2) R1 VADJ = 1.22V IADJ = 30nA AT 25°C OUTPUT RANGE = 1.22V TO 20V 1763 F02 Figure 2. Adjustable Operation The adjustable device is tested and specified with the ADJ pin tied to the OUT pin for an output voltage of 1.22V. Specifications for output voltages greater than 1.22V will be proportional to the ratio of the desired output voltage to 1.22V: VOUT/1.22V. For example, load regulation for an output current change of 1mA to 500mA is – 2mV typical at VOUT = 1.22V. At VOUT = 12V, load regulation is: (12V/1.22V)(–2mV) = – 19.6mV Bypass Capacitance and Low Noise Performance The LT1763 regulators may be used with the addition of a bypass capacitor from VOUT to the BYP pin to lower output voltage noise. A good quality low leakage capacitor is recommended. This capacitor will bypass the reference of the regulator, providing a low frequency noise pole. The noise pole provided by this bypass capacitor will lower the output voltage noise to as low as 20µVRMS with the addition of a 0.01µF bypass capacitor. Using a bypass capacitor has the added benefit of improving transient response. With no bypass capacitor and a 10µF output capacitor, a 10mA to 500mA load step will settle to within 1% of its final value in less than 100µs. With the addition of a 0.01µF bypass capacitor, the output will settle to within 1% for a 10mA to 500mA load step in less than 10µs, with total output voltage deviation of less than 2.5% (see LT1763-5 Transient Response in the Typical Performance Characteristics). However, regulator start-up time is inversely proportional to the size of the bypass capacitor, slowing to 15ms with a 0.01µF bypass capacitor and 10µF output capacitor. Output Capacitance and Transient Response The LT1763 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 3.3µF with an ESR of 3Ω or less is recommended to prevent oscillations. The LT1763-X is a micropower device and output transient response will be a function of output capacitance. Larger values of output capacitance decrease the peak deviations and provide improved transient response for larger load current changes. Bypass capacitors, used to decouple individual components powered by the LT1763-X, will increase the effective output capacitor value. With larger capacitors used to bypass the reference (for low noise operation), larger values of output capacitors are needed. For 100pF of bypass capacitance, 4.7µF of output capacitor is recommended. With a 1000pF bypass capacitor or larger, a 6.8µF output capacitor is recommended. The shaded region of Figure 3 defines the range over which the LT1763 regulators are stable. The minimum ESR needed is defined by the amount of bypass capacitance used, while the maximum ESR is 3Ω. 4.0 3.5 3.0 STABLE REGION 2.5 ESR (Ω) plus the ADJ pin bias current. The ADJ pin bias current, 30nA at 25°C, flows through R2 into the ADJ pin. The output voltage can be calculated using the formula in Figure 2. The value of R1 should be no greater than 250k to minimize errors in the output voltage caused by the ADJ pin bias current. Note that in shutdown the output is turned off and the divider current will be zero. Curves of ADJ Pin Voltage vs Temperature and ADJ Pin Bias Current vs Temperature appear in the Typical Performance Characteristics section. 2.0 CBYP = 0 CBYP = 100pF 1.5 CBYP = 330pF CBYP ≥ 1000pF 1.0 0.5 0 1 3 2 4 5 6 7 8 9 10 OUTPUT CAPACITANCE (µF) 1763 F03 Figure 3. Stability 1763fa 12 LT1763 Series U U W U APPLICATIONS INFORMATION 20 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF 0 CHANGE IN VALUE (%) X5R –20 –40 –60 Y5V –80 –100 0 2 4 14 8 6 10 12 DC BIAS VOLTAGE (V) 16 1763 F04 Figure 4. Ceramic Capacitor DC Bias Characteristics Extra consideration must be given to the use of ceramic capacitors. Ceramic capacitors are manufactured with a variety of dielectrics, each with different behavior across temperature and applied voltage. The most common dielectrics used are Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high capacitances in a small package, but exhibit strong voltage and temperature coefficients as shown in Figures 4 and 5. 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. 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 1763 F05 Figure 5. Ceramic Capacitor Temperature Characteristics 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. The resulting voltages produced can cause appreciable amounts of noise, especially when a ceramic capacitor is used for noise bypassing. A ceramic capacitor produced Figure 6’s trace in response to light tapping from a pencil. Similar vibration induced behavior can masquerade as increased output voltage noise. Thermal Considerations LT1763-5 COUT = 10µF CBYP = 0.01µf ILOAD = 100mA The power handling capability of the device will be limited by the maximum rated junction temperature (125°C). The power dissipated by the device will be made up of two components: VOUT 500µV/DIV 1. Output current multiplied by the input/output voltage differential: (IOUT)(VIN – VOUT), and 100ms/DIV 1763 F06 Figure 6. Noise Resulting from Tapping on a Ceramic Capacitor 2. GND pin current multiplied by the input voltage: (IGND)(VIN). The GND pin current can be found by examining the GND Pin Current curves in the Typical Performance Characteristics. Power dissipation will be equal to the sum of the two components listed above. 1763fa 13 LT1763 Series U U W U APPLICATIONS INFORMATION The LT1763 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 table lists thermal resistance for several different board sizes and copper areas. All measurements were taken in still air on 3/32" FR-4 board with one ounce copper. Table 1. Measured Thermal Resistance COPPER AREA THERMAL RESISTANCE TOPSIDE* BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT) 2500mm2 2500mm2 2500mm2 60°C/W 1000mm2 2500mm2 2500mm2 60°C/W 2 2 68°C/W 2 74°C/W 2 86°C/W 2 225mm 2 100mm 50mm 2 2500mm 2 2500mm 2 2500mm 2500mm 2500mm 2500mm *Device is mounted on topside. 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 250mA 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) = 250mA VIN(MAX) = 6V IGND at (IOUT = 250mA, VIN = 6V) = 5mA So, P = 250mA(6V – 3.3V) + 5mA(6V) = 0.71W The thermal resistance will be in the range of 60°C/W to 86°C/W depending on the copper area. So the junction temperature rise above ambient will be approximately equal to: 0.71W(75°C/W) = 53.3°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 + 53.3°C = 103.3°C Protection Features The LT1763 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 which can be plugged in backward. The output of the LT1763-X 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 500kΩ or higher, limiting current flow to less than 100µA. 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. 1763fa 14 LT1763 Series U U W U APPLICATIONS INFORMATION 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 100k) in series with a diode when pulled above ground. When the IN pin of the LT1763-X 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. In situations where the ADJ pin is connected to a resistor divider that would pull the ADJ pin above its 7V clamp voltage if the output is pulled high, the ADJ pin input current must be limited to less than 5mA. For example, a resistor divider is used to provide a regulated 1.5V output from the 1.22V reference when the output is forced to 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 output and ADJ pin divided by the 5mA maximum current into the ADJ pin yields a minimum top resistor value of 2.6k. REVERSE OUTPUT CURRENT (µA) 100 TJ = 25°C 90 VIN = 0V CURRENT FLOWS 80 INTO OUTPUT PIN 70 VOUT = VADJ (LT1763) LT1763 60 LT1763-1.8 50 LT1763-2.5 LT1763-3 40 30 20 LT1763-5 10 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 7. LT1763-1.5 LT1763-3.3 0 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE (V) 9 10 1763 F07 Figure 7. Reverse Output Current U TYPICAL APPLICATION S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 .245 MIN .160 ±.005 .030 ±.005 TYP 7 6 5 .053 – .069 (1.346 – 1.752) .150 – .157 (3.810 – 3.988) NOTE 3 .228 – .244 (5.791 – 6.197) 1 2 3 4 RECOMMENDED SOLDER PAD LAYOUT 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) .004 – .010 (0.101 – 0.254) .050 (1.270) BSC .014 – .019 (0.355 – 0.483) TYP .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) 0°– 8° TYP .016 – .050 (0.406 – 1.270) SO8 0303 1763fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 15 LT1763 Series U TYPICAL APPLICATION Paralleling of Regulators for Higher Output Current R1 0.1Ω IN + C1 10µF VIN > 3.8V OUT SENSE LT1763-3.3 + C4 0.01µF SHDN BYP GND 3.3V 1A C2 10µF R2 0.1Ω IN OUT C5 0.01µF LT1763 SHDN R3 2.2k SHDN GND R4 2.2k 3 + BYP ADJ R7 1.21k 8 1/2 LT1490 2 – 4 R6 2k R5 10k 1 C3 0.01µF 1763 TA03 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1120 125mA Low Dropout Regulator with 20µA IQ Includes 2.5V Reference and Comparator LT1121 150mA Micropower Low Dropout Regulator 30µA IQ, SOT-223 Package LT1129 700mA Micropower Low Dropout Regulator 50µA Quiescent Current LT1175 500mA Negative Low Dropout Micropower Regulator 45µA IQ, 0.26V Dropout Voltage, SOT-223 Package LT1521 300mA Low Dropout Micropower Regulator with Shutdown 15µA IQ, Reverse Battery Protection LT1529 3A Low Dropout Regulator with 50µA IQ 500mV Dropout Voltage LT1613 1.4MHz Single-Cell Micropower DC/DC Converter SOT-23 Package, Internally Compensated LT1761 Series 100mA, Low Noise, Low Dropout Micropower Regulators in SOT-23 20µA Quiescent Current, 20µVRMS Noise, ThinSOT LT1762 Series 150mA, Low Noise, LDO Micropower Regulators 25µA Quiescent Current, 20µVRMS Noise, MS8 LT1764A 3A, Fast Transient Response Low Dropout Regulator 340mV Dropout Voltage, DD, TO220 LT1962 300mA, Fast Transient Response Low Dropout Regulator 270mV Dropout Voltage, 20µVRML, MS8 LT1963A 1.5A, Fast Transient Response Low Dropout Regulator 340mV Dropout Voltage, 40µVRML, DD, TO220, S8, SOT-223 LT3010 50mA, 80V Low Noise, LDO Micropower Regulator 300mV Dropout Voltage, MS8E 1763fa 16 Linear Technology Corporation LT/TP 1003 1K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 1999