LT1762EMS8

LT1762 Series 150mA, Low Noise, LDO Micropower Regulators U Dropout Voltage 400 350 20 40 60 80 100 120 140 160 OUTPUT CURRENT (mA) 1762 TA02 FEATURES s s s s s s s s s s s DESCRIPTIO s s s s Low Noise: 20µVRMS (10Hz to 100kHz) Low Quiescent Current: 25µA Wide Input Voltage Range: 1.8V to 20V Output Current: 150mA Very Low Shutdown Current: < 1µA Low Dropout Voltage: 300mV No Protection Diodes Needed Fixed Output Voltages: 2.5V, 3V, 3.3V, 5V Adjustable Output from 1.22V to 20V Stable with 2.2µF Output Capacitor Stable with Aluminum, Tantalum or Ceramic Capacitors Reverse Battery Protection No Reverse Current Overcurrent and Overtemperature Protected 8-Lead MSOP Package APPLICATIO S s s s s Cellular Phones Battery-Powered Systems Frequency Synthesizers Noise-Sensitive Instrumentation Systems The LT ®1762 series are micropower, low noise, low dropout regulators. The devices are capable of supplying 150mA of output current with a dropout voltage of 300mV. Designed for use in battery-powered systems, the low 25µA 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 LT1762 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 LT1762 regulators are stable with output capacitors as low as 2.2µF. 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 2.5V, 3V, 3.3V and 5V, and as an adjustable device with a 1.22V reference voltage. The LT1762 regulators are available in the 8-lead MSOP package. , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATION 3.3V Low Noise Regulator DROPOUT VOLTAGE (mV) 300 250 200 150 100 50 0 0 VIN 3.7V TO 20V IN 1µF OUT SENSE LT1762-3.3 0.01µF SHDN BYP GND U U + 3.3V AT 150mA 20µVRMS NOISE 10µF 1762 TA01 1 LT1762 Series ABSOLUTE MAXIMUM RATINGS (Note 1) PACKAGE/ORDER INFORMATION TOP VIEW OUT SENSE/ADJ* BYP GND 1 2 3 4 8 7 6 5 IN NC NC SHDN 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 ORDER PART NUMBER LT1762EMS8 LT1762EMS8-2.5 LT1762EMS8-3 LT1762EMS8-3.3 LT1762EMS8-5 MS8 PART MARKING LTHF LTHG LTHH LTHJ LTHK MS8 PACKAGE 8-LEAD PLASTIC MSOP *PIN 2: SENSE FOR LT1762-2.5/ LT1762-3/LT1762-3.3/LT1762-5 ADJ FOR LT1762 TJMAX = 150°C, θJA = 125°C/ W SEE THE APPLICATIONS INFORMATION SECTION. Consult factory for Industrial and Military grade parts. The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) PARAMETER Minimum Operating Voltage Regulated Output Voltage (Note 4) CONDITIONS ILOAD = 150mA LT1762-2.5 VIN = 3V, ILOAD = 1mA 3.5V < VIN < 20V, 1mA < ILOAD < 150mA LT1762-3 VIN = 3.5V, ILOAD = 1mA 4V < VIN < 20V, 1mA < ILOAD < 150mA q q q q q q q q q q q q ELECTRICAL CHARACTERISTICS MIN 2.475 2.435 2.970 2.925 3.267 3.220 4.950 4.875 1.208 1.190 TYP 1.8 2.5 2.5 3 3 3.3 3.3 5 5 1.22 1.22 1 1 1 1 1 4 4 MAX 2.3 2.525 2.565 3.030 3.075 3.333 3.380 5.050 5.125 1.232 1.250 5 5 5 5 5 12 25 15 30 17 33 25 50 6 12 UNITS 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 LT1762-3.3 VIN = 3.8V, ILOAD = 1mA 4.3V < VIN < 20V, 1mA < ILOAD < 150mA LT1762-5 ADJ Pin Voltage (Notes 3, 4) Line Regulation LT1762 VIN = 5.5V, ILOAD = 1mA 6V < VIN < 20V, 1mA < ILOAD < 150mA VIN = 2V, ILOAD = 1mA 2.3V < VIN < 20V, 1mA < ILOAD < 150mA ∆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 VIN = 3.5V, ∆ILOAD = 1mA to 150mA VIN = 3.5V, ∆ILOAD = 1mA to 150mA VIN = 4V, ∆ILOAD = 1mA to 150mA VIN = 4V, ∆ILOAD = 1mA to 150mA VIN = 4.3V, ∆ILOAD = 1mA to 150mA VIN = 4.3V, ∆ILOAD = 1mA to 150mA VIN = 6V, ∆ILOAD = 1mA to 150mA VIN = 6V, ∆ILOAD = 1mA to 150mA VIN = 2.3V, ∆ILOAD = 1mA to 150mA VIN = 2.3V, ∆ILOAD = 1mA to 150mA LT1762-2.5 LT1762-3 LT1762-3.3 LT1762-5 LT1762 (Note 3) LT1762-2.5 LT1762-3 LT1762-3.3 LT1762-5 LT1762 (Note 3) Load Regulation q 5 q 9 q 1 q 2 U W U U WW W LT1762 Series The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) PARAMETER Dropout Voltage VIN = VOUT(NOMINAL) (Notes 5, 6) CONDITIONS ILOAD = 1mA ILOAD = 1mA ILOAD = 10mA ILOAD = 10mA ILOAD = 50mA ILOAD = 50mA ILOAD = 150mA ILOAD = 150mA GND Pin Current VIN = VOUT(NOMINAL) (Notes 5, 7) ILOAD = 0mA ILOAD = 1mA ILOAD = 10mA ILOAD = 50mA ILOAD = 150mA COUT = 10µF, CBYP = 0.01µF, ILOAD = 150mA, BW = 10Hz to 100kHz (Notes 3, 8) VOUT = Off to On VOUT = On to Off VSHDN = 0V VSHDN = 20V VIN = 6V, VSHDN = 0V VIN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 150mA VIN = 7V, VOUT = 0V VIN = VOUT(NOMINAL) + 1V, ∆VOUT = – 0.1V VIN = – 20V, VOUT = 0V LT1762-2.5 LT1762-3 LT1762-3.3 LT1762-5 LT1762 (Note 3) 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 q q q q q ELECTRICAL CHARACTERISTICS MIN TYP 0.09 0.15 MAX 0.15 0.19 0.21 0.25 0.27 0.31 0.33 0.40 65 120 500 1.8 7 100 2 UNITS V V V V V V V V µA µA µA mA mA µVRMS nA V V µA µA q 0.21 q 0.27 q q q q q q 25 70 350 1.3 4 20 30 0.25 0.8 0.65 0.1 1 0.1 50 65 300 160 Output Voltage Noise ADJ Pin Bias Current Shutdown Threshold SHDN Pin Current (Note 9) Quiescent Current in Shutdown Ripple Rejection Current Limit Input Reverse Leakage Current Reverse Output Current (Note 10) 1 µA dB mA mA 1 10 10 10 10 5 20 20 20 20 10 mA µA µA µA µA µA Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1762 regulators are tested and specified under pulse load conditions such that TJ ≈ TA. The LT1762 is 100% tested at 25°C. Performance at – 40°C and 125°C is assured by design, characterization and correlation with statistical process controls. Note 3: The LT1762 (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 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 LT1762 (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. 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) 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. 3 LT1762 Series TYPICAL PERFORMANCE CHARACTERISTICS Typical Dropout Voltage 500 450 DROPOUT VOLTAGE (mV) DROPOUT VOLTAGE (mV) DROPOUT VOLTAGE (mV) 400 350 300 250 200 150 100 50 0 0 20 40 60 80 100 120 140 160 LOAD CURRENT (mA) 1762 G01 TJ = 125°C TJ = 25°C Quiescent Current 40 35 QUIESCENT CURRENT (µA) VIN = 6V RL = ∞, IL = 0 (LT1762-2.5/-3/-3.3/-5) RL = 250k, IL = 5µA (LT1762) OUTPUT VOLTAGE (V) 25 20 15 10 5 0 –50 –25 0 25 50 75 100 125 VSHDN = VIN 2.51 2.50 2.49 2.48 2.47 2.46 –50 –25 0 25 50 75 100 125 OUTPUT VOLTAGE (V) 30 TEMPERATURE (°C) 1762 G04 LT1762-3.3 Output Voltage 3.360 IL = 1mA 3.345 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 3.315 3.300 3.285 3.270 3.255 3.240 –50 –25 0 25 50 75 100 125 5.025 5.000 4.975 4.950 4.925 4.900 –50 –25 0 25 50 75 100 125 ADJ PIN VOLTAGE (V) 3.330 TEMPERATURE (°C) 1762 G07 4 UW Guaranteed Dropout Voltage 500 450 400 350 300 250 200 150 100 50 0 0 20 40 60 80 100 120 140 160 LOAD CURRENT (mA) 1762 G02 Dropout Voltage 500 450 = TEST POINTS TJ ≤ 125°C 400 350 300 250 200 150 100 50 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 IL = 1mA IL = 50mA IL = 10mA IL = 150mA TJ ≤ 25°C 1762 G03 LT1762-2.5 Output Voltage 2.54 IL = 1mA 2.53 2.52 3.045 3.030 3.015 3.000 2.985 2.970 2.955 3.060 LT1762-3 Output Voltage IL = 1mA 2.940 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) 1762 G05 TEMPERATURE (°C) 1762 G06 LT1762-5 Output Voltage 5.100 IL = 1mA 5.075 5.050 1.235 1.230 1.225 1.220 1.215 1.210 1.205 1.240 LT1762 ADJ Pin Voltage IL = 1mA 1.200 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) 1762 G08 TEMPERATURE (°C) 1762 G09 LT1762 Series TYPICAL PERFORMANCE CHARACTERISTICS LT1762-2.5 Quiescent Current 400 350 TJ = 25°C RL = ∞ QUIESCENT CURRENT (µA) QUIESCENT CURRENT (µA) 300 250 200 150 100 50 0 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 VSHDN = VIN VSHDN = 0V QUIESCENT CURRENT (µA) LT1762-5 Quiescent Current 400 350 TJ = 25°C RL = ∞ QUIESCENT CURRENT (µA) 30 25 20 15 10 5 QUIESCENT CURRENT (µA) 250 200 150 VSHDN = VIN 100 50 0 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 VSHDN = 0V GND PIN CURRENT (µA) 300 LT1762-3 GND Pin Current 800 700 TJ = 25°C VIN = VSHDN *FOR VOUT = 3V 800 700 GND PIN CURRENT (µA) GND PIN CURRENT (µA) GND PIN CURRENT (µA) 600 500 400 300 200 100 0 0 1 RL = 120Ω IL = 25mA* RL = 300Ω IL = 10mA* RL = 3k IL = 1mA* 2 34567 INPUT VOLTAGE (V) 8 9 10 UW 1762 G10 1762 G13 1762 G16 LT1762-3 Quiescent Current 400 350 300 250 200 150 100 50 0 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 VSHDN = VIN VSHDN = 0V TJ = 25°C RL = ∞ 400 350 300 250 200 150 100 50 0 LT1762-3.3 Quiescent Current TJ = 25°C RL = ∞ VSHDN = VIN 0 1 2 VSHDN = 0V 34567 INPUT VOLTAGE (V) 8 9 10 1762 G11 1762 G12 LT1762 Quiescent Current 800 VSHDN = VIN LT1762-2.5 GND Pin Current 700 600 500 400 300 200 100 RL = 2.5k IL = 1mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 RL = 100Ω IL = 25mA* RL = 250Ω IL = 10mA* TJ = 25°C VIN = VSHDN *FOR VOUT = 2.5V TJ = 25°C RL = 250k VSHDN = 0V 0 0 2 4 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 1762 G14 0 1762 G15 LT1762-3.3 GND Pin Current TJ = 25°C VIN = VSHDN *FOR VOUT = 3.3V LT1762-5 GND Pin Current 800 700 600 500 400 300 200 100 8 9 10 600 500 400 300 200 100 0 0 1 2 RL = 132Ω IL = 25mA* RL = 200Ω IL = 25mA* TJ = 25°C VIN = VSHDN *FOR VOUT = 5V RL = 500Ω IL = 10mA* RL = 330Ω IL = 10mA* RL = 3.3k IL = 1mA* 34567 INPUT VOLTAGE (V) RL = 5k IL = 1mA* 0 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 1762 G17 1762 G18 5 LT1762 Series TYPICAL PERFORMANCE CHARACTERISTICS LT1762 GND Pin Current 800 700 TJ = 25°C VIN = VSHDN *FOR VOUT = 1.22V GND PIN CURRENT (mA) GND PIN CURRENT (µA) 600 500 400 300 200 100 0 0 1 RL = 48.8Ω IL = 25mA* RL = 122Ω IL = 10mA* GND PIN CURRENT (mA) RL = 1.22k IL = 1mA* 2 34567 INPUT VOLTAGE (V) 8 9 10 LT1762-3.3 GND Pin Current 5.0 4.5 GND PIN CURRENT (mA) GND PIN CURRENT (mA) GND PIN CURRENT (mA) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 1 2 RL = 33Ω IL = 100mA* RL = 66Ω IL = 50mA* RL = 22Ω IL = 150mA* TJ = 25°C VIN = VSHDN *FOR VOUT = 3.3V 34567 INPUT VOLTAGE (V) GND Pin Current vs ILOAD 5.0 4.5 GND PIN CURRENT (mA) VIN = VOUT(NOMINAL) + 1V SHDN PIN THRESHOLD (V) SHDN PIN THRESHOLD (V) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 20 40 60 80 100 120 140 160 OUTPUT CURRENT (mA) 1762 G25 6 UW 1762 G19 LT1762-2.5 GND Pin Current 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 RL = 25Ω IL = 100mA* RL = 50Ω IL = 50mA* RL = 16.7Ω IL = 150mA* TJ = 25°C VIN = VSHDN *FOR VOUT = 2.5V 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 LT1762-3 GND Pin Current TJ = 25°C VIN = VSHDN *FOR VOUT = 3V RL = 20Ω IL = 150mA* RL = 30Ω IL = 100mA* RL = 60Ω IL = 50mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 1762 G20 1762 G21 LT1762-5 GND Pin Current 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 8 9 10 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 RL = 50Ω IL = 100mA* RL = 100Ω IL = 50mA* TJ = 25°C VIN = VSHDN *FOR VOUT = 5V RL = 33.3Ω IL = 150mA* 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 LT1762 GND Pin Current TJ = 25°C VIN = VSHDN *FOR VOUT = 1.22V RL = 8.07Ω IL = 150mA* RL = 12.2Ω IL = 100mA* RL = 24.4Ω IL = 50mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 1762 G22 1762 G23 1762 G24 SHDN Pin Threshold (On-to-Off) 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 –50 –25 50 0 75 25 TEMPERATURE (°C) 100 125 IL = 1mA 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 SHDN Pin Threshold (Off-to-On) IL = 150mA IL = 1mA 0 –50 –25 50 0 75 25 TEMPERATURE (°C) 100 125 1762 G26 1762 G27 LT1762 Series TYPICAL PERFORMANCE CHARACTERISTICS SHDN Pin Input Current 1.4 SHDN PIN INPUT CURRENT (mA) SHDN PIN INPUT CURRENT (µA) 1.6 VSHDN = 20V 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 –50 –25 0 25 50 75 100 125 1.2 1.0 0.8 0.6 0.4 0.2 0 ADJ PIN BIAS CURRENT (nA) 0 1 2 345678 SHDN PIN VOLTAGE (V) Current Limit 500 450 SHORT-CIRCUIT CURRENT (mA) VOUT = 0V SHORT-CIRCUIT CURRENT (mA) 400 350 300 250 200 150 100 50 0 0 1 4 3 2 5 INPUT VOLTAGE (V) 6 7 1762 G31 400 350 300 250 200 150 100 50 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 REVERSE OUTPUT CURRENT (µA) Reverse Output Current 30 REVERSE OUTPUT CURRENT (µA) 25 20 15 RIPPLE REJECTION (dB) RIPPLE REJECTION (dB) VIN = 0V VOUT = 1.22V (LT1762) VOUT = 2.5V (LT1762-2.5) VOUT = 3V (LT1762-3) VOUT = 3.3V (LT1762-3.3) VOUT = 5V (LT1762-5) LT1762-2.5/-3/-3.3/-5 10 LT1762 5 0 –50 –25 50 25 0 75 TEMPERATURE (°C) UW 9 1762 G28 SHDN Pin Input Current 140 120 100 80 60 40 20 ADJ Pin Bias Current 10 0 –50 –25 TEMPERATURE (°C) 1762 G29 50 25 0 75 TEMPERATURE (°C) 100 125 1762 G30 Current Limit 500 450 VIN = 7V VOUT = 0V 100 90 80 70 60 50 40 30 20 10 0 Reverse Output Current TJ = 25°C, VIN = 0V CURRENT FLOWS INTO OUTPUT PIN VOUT = VSENSE (LT1762-2.5/-3/-3.3/-5) VOUT = VADJ (LT1762) LT1762-2.5 LT1762-3 LT1762 LT1762-3.3 LT1762-5 0 1 2 345678 OUTPUT VOLTAGE (V) 9 10 1762 G32 1762 G33 Input Ripple Rejection 80 70 60 50 40 30 20 10 0 10 IL = 150mA VIN = VOUT(NOMINAL) + 1V + 50mVRMS RIPPLE CBYP = 0 100 COUT = 2.2µF COUT = 10µF 80 70 60 50 40 30 20 10 0 1k 10k FREQUENCY (Hz) 100k 1M 1762 G35 Input Ripple Rejection CBYP = 0.01µF CBYP = 1000pF CBYP = 100pF IL = 150mA VIN = VOUT(NOMINAL) + 1V + 50mVRMS RIPPLE COUT = 10µF 10 100 1k 10k FREQUENCY (Hz) 100k 1M 1762 G36 100 125 1762 G34 7 LT1762 Series TYPICAL PERFORMANCE CHARACTERISTICS Ripple Rejection 68 66 MINIMUM INPUT VOLTAGE (V) RIPPLE REJECTION (dB) 64 62 60 58 56 54 VIN = VOUT (NOMINAL) + 1V + 0.5VP-P RIPPLE AT f = 120Hz IL = 150mA 0 25 50 75 100 125 TEMPERATURE (°C) 1762 G37 LOAD REGULATION (mV) 52 –50 –25 Output Noise Spectral Density CBYP = 0 OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) 10 COUT = 10µF IL = 150mA LT1762-5 LT1762-3.3 1 LT1762-2.5 LT1762 0.1 LT1762-3 0.01 10 100 RMS Output Noise vs Bypass Capacitor 160 140 LT1762-5 COUT = 10µF IL = 150mA f = 10Hz TO 100kHz LT1762-3.3 100 80 60 40 LT1762-2.5 20 0 10 100 CBYP (pF) 1762 G42 OUTPUT NOISE (µVRMS) OUTPUT NOISE (µVRMS) 120 LT1762-3 LT1762 8 UW LT1762 Minimum Input Voltage 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 IL = 1mA VOUT = 1.22V 0 5 Load Regulation LT1762 LT1762-3 IL = 150mA –5 –10 –15 –20 VIN = VOUT(NOMINAL) + 1V ∆IL = 1mA TO 150mA 0 25 50 LT1762-2.5 LT1762-3.3 LT1762-5 –25 –50 –25 75 100 125 TEMPERATURE (°C) 1762 G38 1762 G39 Output Noise Spectral Density 10 COUT = 10µF IL = 150mA LT1762-5 1 CBYP = 100pF LT1762 CBYP = 1000pF 0.1 CBYP = 0.01µF 1k 10k FREQUENCY (Hz) 100k 1762 G40 0.01 10 100 1k 10k FREQUENCY (Hz) 100k 1762 G41 RMS Output Noise vs Load Current (10Hz to 100kHz) 160 140 120 100 80 60 40 20 1000 10000 0 0.01 0.1 LT1762-5 LT1762 10 100 1 LOAD CURRENT (mA) 1000 1762 G43 COUT = 10µF CBYP = 0 CBYP = 0.01µF LT1762-5 LT1762 LT1762 Series TYPICAL PERFORMANCE CHARACTERISTICS LT1762-5 10Hz to 100kHz Output Noise CBYP = 0 LT1762-5 10Hz to 100kHz Output Noise CBYP = 100pF VOUT 100µV/DIV COUT = 10µF IL = 150mA LT1762-5 10Hz to 100kHz Output Noise CBYP = 1000pF VOUT 100µV/DIV COUT = 10µF IL = 150mA LT1762-5 Transient Response CBYP = 0 0.3 OUTPUT VOLTAGE DEVIATION (V) OUTPUT VOLTAGE DEVIATION (V) 0.2 0.1 0 –0.1 –0.2 –0.3 LOAD CURRENT (mA) LOAD CURRENT (mA) 150 100 50 0 0 400 800 1200 TIME (µs) 1600 2000 1762 G48 UW 1ms/DIV 1ms/DIV VOUT 100µV/DIV 1762 G44 COUT = 10µF IL = 150mA 1ms/DIV 1762 G45 LT1762-5 10Hz to 100kHz Output Noise CBYP = 0.01µF VOUT 100µV/DIV 1762 G46 COUT = 10µF IL = 150mA 1ms/DIV 1762 G47 LT1762-5 Transient Response CBYP = 0.01µF VIN = 6V CIN = 10µF COUT = 10µF 0.04 0.02 0 –0.02 –0.04 VIN = 6V CIN = 10µF COUT = 10µF 150 100 50 0 0 40 80 120 TIME (µs) 160 200 1762 G49 9 LT1762 Series PIN FUNCTIONS OUT (Pin 1): Output. The output supplies power to the load. A minimum output capacitor of 2.2µF 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 LT1762 (LT1762-2.5/LT1762-3/LT1762-3.3/ LT1762-5), 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). 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 LT1762, this is the input to the error amplifier. This pin is internally clamped to ± 7V. It has a bias current of 30nA which flows into the pin (see curve of ADJ Pin Bias Current vs Temperature in the Typical Performance Characteristics). The ADJ pin voltage is 1.22V referenced to ground and the output voltage range is 1.22V to 20V. BYP (Pins 3): Bypass. The BYP pin is used to bypass the reference of the LT1762 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 (Pin 4): Ground. SHDN (Pin5): Shutdown. The SHDN pin is used to put the LT1762 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 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 LT1762 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. RP 10 U U U 8 IN LT1762 OUT 1 + VIN 5 SHDN SENSE GND 4 2 + LOAD RP 1762 F01 Figure 1. Kelvin Sense Connection LT1762 Series APPLICATIONS INFORMATION The LT1762 series are 150mA low dropout regulators with micropower quiescent current and shutdown. The devices are capable of supplying 150mA 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 (25µA) drops to less than 1µA in shutdown. In addition to the low quiescent current, the LT1762 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 LT1762-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 LT1762 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 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. 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 150mA is –1mV typical at VOUT = 1.22V. At VOUT = 12V, load regulation is: (12V/1.22V)(–1mV) = – 9.8mV Bypass Capacitance and Low Noise Performance The LT1762 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 150mA 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 stay within 1% for a 10mA to 150mA load step (see LT1762-5 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. IN VIN OUT VOUT + LT1762 ADJ GND R1 1762 F02 R2  R2 VOUT = 1.22V  1 +  + (IADJ )(R2)  R1 VADJ = 1.22V IADJ = 30nA AT 25°C OUTPUT RANGE = 1.22V TO 20V Figure 2. Adjustable Operation U W U U 11 LT1762 Series APPLICATIONS INFORMATION Output Capacitance and Transient Response The LT1762 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 2.2µF with an ESR of 3Ω or less is recommended to prevent oscillations. The LT1762-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 LT1762-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, 3.3µF of output capacitor is recommended. With a 330pF bypass capacitor or larger, a 4.7µF output capacitor is recommended. The shaded region of Figure 3 defines the range over which the LT1762 regulators are stable. The minimum ESR needed is defined by the amount of bypass capacitance used, while the maximum ESR is 3Ω. 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 20 0 CHANGE IN VALUE (%) 4.0 3.5 3.0 STABLE REGION 2.5 ESR (Ω) 2.0 1.5 1.0 0.5 0 1 3 2 4 5 6 7 8 9 10 OUTPUT CAPACITANCE (µF) 1762 F03 CHANGE IN VALUE (%) CBYP = 0 CBYP = 100pF CBYP = 330pF CBYP ≥ 3300pF Figure 3. Stability –80 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF 50 25 75 0 TEMPERATURE (°C) 100 125 –100 –50 –25 12 U W U U BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF X5R –20 –40 –60 Y5V –80 –100 0 2 4 8 6 10 12 DC BIAS VOLTAGE (V) 14 16 1762 F04 Figure 4. Ceramic Capacitor DC Bias Characteristics 40 20 0 –20 –40 –60 Y5V X5R 1762 F05 Figure 5. Ceramic Capacitor Temperature Characteristics LT1762 Series APPLICATIONS INFORMATION 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. 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. The GND pin current can be found by examining the GND Pin Current curves in the Typical Performance Characteristics. Power dissipation will be equal to the sum of the two components listed above. The LT1762 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 100ms/DIV 1762 F05 LT1762-5 COUT = 10µF CBYP = 0.01µf ILOAD = 100mA VOUT 500µV/DIV Figure 6. Noise Resulting from Tapping on a Ceramic Capacitor Thermal Considerations 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: 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). U W U U THERMAL RESISTANCE BOARD AREA 2500mm 2500mm 2 2 TOPSIDE* 2500mm 1000mm 2 2 BACKSIDE 2500mm 2500mm 2 2 (JUNCTION-TO-AMBIENT) 110°C/W 115°C/W 120°C/W 130°C/W 140°C/W 225mm2 100mm 50mm 2 2 2500mm2 2500mm 2500mm 2 2 2500mm2 2500mm 2500mm 2 2 *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 50mA and a maximum ambient temperature of 50°C, what will the maximum junction temperature be? The power dissipated by the device will be equal to: IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)) 13 LT1762 Series APPLICATIONS INFORMATION where, IOUT(MAX) = 150mA VIN(MAX) = 6V IGND at (IOUT = 150mA, VIN = 6V) = 5mA So, P = 150mA(6V – 3.3V) + 5mA(6V) = 0.44W The thermal resistance will be in the range of 110°C/W to 140°C/W depending on the copper area. So the junction temperature rise above ambient will be approximately equal to: 0.44W(125°C/W) = 55°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 + 55°C = 105°C Protection Features The LT1762 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 LT1762-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. 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. 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. 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. When the IN pin of the LT1762-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. 14 U W U U LT1762 Series APPLICATIONS INFORMATION 100 REVERSE OUTPUT CURRENT (µA) 90 80 70 60 50 40 30 20 10 0 0 TJ = 25°C VIN = 0V CURRENT FLOWS INTO OUTPUT PIN VOUT = VSENSE (LT1762-2.5/LT1762-3 LT1762-3.3/LT1762-5) VOUT = VADJ (LT1762) LT1762-3 1 Figure 7. Reverse Output Current PACKAGE DESCRIPTION MS8 Package 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) 0.007 (0.18) 0.021 ± 0.006 (0.53 ± 0.015) * DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE 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. U U W U U LT1762 LT1762-2.5 LT1762-5 LT1762-3.3 2 345678 OUTPUT VOLTAGE (V) 9 10 1762 F07 0.118 ± 0.004* (3.00 ± 0.102) 8 76 5 0.193 ± 0.006 (4.90 ± 0.15) 0.118 ± 0.004** (3.00 ± 0.102) 1 0.040 ± 0.006 (1.02 ± 0.15) 0° – 6° TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) BSC 23 4 0.034 ± 0.004 (0.86 ± 0.102) 0.006 ± 0.004 (0.15 ± 0.102) MSOP (MS8) 1098 15 LT1762 Series TYPICAL APPLICATION Paralleling of Regulators for Higher Output Current R1 0.1Ω + VIN > 3.7V SHDN RELATED PARTS PART NUMBER LT1120 LT1121 LT1129 LT1175 LT1521 LT1529 LT1611 LT1613 LTC1627 LT1761 Series LT1763 Series DESCRIPTION 125mA Low Dropout Regulator with 20µA IQ 150mA Micropower Low Dropout Regulator 700mA Micropower Low Dropout Regulator 500mA Negative Low Dropout Micropower Regulator 300mA Low Dropout Micropower Regulator with Shutdown 3A Low Dropout Regulator with 50µA IQ Inverting 1.4MHz Switching Regulator 1.4MHz Single-Cell Micropower DC/DC Converter High Efficiency Synchronous Step-Down Switching Regulator 100mA, Low Noise, Low Dropout Micropower Regulators in SOT-23 500mA, Low Noise, LDO Micropower Regulators COMMENTS Includes 2.5V Reference and Comparator 30µA IQ, SOT-223 Package 50µA Quiescent Current 45µA IQ, 0.26V Dropout Voltage, SOT-223 Package 15µA IQ, Reverse Battery Protection 500mV Dropout Voltage 5V to – 5V at 150mA, Low Output Noise, SOT-23 Package SOT-23 Package, Internally Compensated Burst ModeTM Operation, Monolithic, 100% Duty Cycle 20µA Quiescent Current, 20µVRMS Noise 30µA Quiescent Current, 20µVRMS Noise Burst Mode is a trademark of Linear Technology Corporation. 16 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com U IN C1 10µF OUT FB LT1762-3.3 C4 0.01µF + 3.3V 300mA C2 10µF SHDN BYP GND R2 0.1Ω IN LT1762 BYP SHDN ADJ GND OUT C5 0.01µF R6 2k R7 1.21k R3 2.2k R4 2.2k 3 + – 8 1 R5 10k 1/2 LT1490 2 4 1762 TA03 C3 0.01µF 1762fs sn1762 LT/TP 0899 4K • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 1999