LTBKJ

LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 100mA, Low Voltage, Very Low Dropout Linear Regulator FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO VIN Range: 0.9V to 10V Minimum Input Voltage: 0.9V Dropout Voltage: 150mV Typical Output Current: 100mA Adjustable Output (VREF = VOUT(MIN) = 200mV) Fixed Output Voltages: 1.2V, 1.5V, 1.8V Stable with Low ESR, Ceramic Output Capacitors (2.2µF Minimum) 0.2% Load Regulation from 0mA to 100mA Quiescent Current: 120µA (Typ) 3µA Typical Quiescent Current in Shutdown Current Limit Protection Reverse-Battery Protection No Reverse Current Thermal Limiting with Hysteresis 8-Lead DFN (3mm × 3mm) and MSOP Packages The LT®3020 is a very low dropout voltage (VLDOTM) linear regulator that operates from input supplies down to 0.9V. This device supplies 100mA of output current with a typical dropout voltage of 150mV. The LT3020 is ideal for low input voltage to low output voltage applications, providing comparable electrical efficiency to that of a switching regulator. The LT3020 regulator optimizes stability and transient response with low ESR, ceramic output capacitors as small as 2.2µF. Other LT3020 features include 0% line regulation and 0.2% typical load regulation. In shutdown, quiescent current typically drops to 3µA. Internal protection circuitry includes reverse-battery protection, current limiting, thermal limiting with hysteresis, and reverse-current protection. The LT3020 is available as an adjustable output device with an output range down to the 200mV reference. Three fixed output voltages, 1.2V, 1.5V and 1.8V, are also available. The LT3020 regulator is available in the low profile (0.75mm) 8-lead (3mm × 3mm) DFN package with exposed pad and the 8-lead MSOP package. , LTC and LT are registered trademarks of Linear Technology Corporation. VLDO is a trademark of Linear Technology Corporation. APPLICATIO S ■ ■ ■ ■ ■ Low Current Regulators Battery-Powered Systems Cellular Phones Pagers Wireless Modems TYPICAL APPLICATIO VIN 1.8V 2.2µF IN OUT LT3020-1.5 SHDN GND Minimum Input Voltage 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 IL = 100mA 1.8V to 1.5V, 100mA VLDO Regulator VOUT 1.5V 100mA MINIMUM INPUT VOLTAGE (V) 2.2µF 3020 TA01 U 3020 TA02 U U sn3020 3020fas 1 LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 ABSOLUTE AXI U RATI GS IN Pin Voltage ........................................................ ± 10V OUT Pin Voltage .................................................... ± 10V Input-to-Output Differential Voltage ....................... ± 10V ADJ Pin Voltage .................................................... ± 10V SHDN Pin Voltage ................................................. ± 10V Output Short-Circut Duration .......................... Indefinite PACKAGE/ORDER I FOR ATIO TOP VIEW OUT 1 OUT 2 ADJ 3 GND 4 9 8 7 6 5 IN IN NC SHDN ORDER PART NUMBER LT3020EDD OUT 1 OUT 2 OUT 3 GND 4 DD PART MARKING DD PACKAGE 8-LEAD (3mm × 3mm) PLASTIC DFN LAEX TJMAX = 125°C, θJA = 35°C/ W*, θJC = 3°C/ W EXPOSED PAD IS GND (PIN 9) CONNECT TO PIN 4 *SEE THE APPLICATIONS INFORMATION SECTION ORDER PART NUMBER TOP VIEW OUT OUT ADJ GND 1 2 3 4 8 7 6 5 IN IN NC SHDN LT3020EMS8 MS8 PACKAGE 8-LEAD PLASTIC MSOP MS8 PART MARKING LTAGL TJMAX = 150°C, θJA = 125°C/ W, θJC = 40°C/ W SEE THE APPLICATIONS INFORMATION SECTION Consult factory for parts specified with wider operating temperature ranges. 2 U U W WW U W (Note 1) Operating Junction Temperature Range (Notes 2, 3) .......................................... – 40°C to 125°C Storage Temperature Range DD .................................................... – 65°C to 125°C MS8 .................................................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C TOP VIEW 8 9 7 6 5 IN IN NC SHDN ORDER PART NUMBER LT3020EDD-1.2 LT3020EDD-1.5 LT3020EDD-1.8 DD8 PART MARKING LBKC LBKD LBKF ORDER PART NUMBER DD PACKAGE 8-LEAD (3mm × 3mm) PLASTIC DFN TJMAX = 125°C, θJA = 35°C/ W*, θJC = 3°C/ W EXPOSED PAD IS GND (PIN 9) CONNECT TO PIN 4 *SEE THE APPLICATIONS INFORMATION SECTION TOP VIEW OUT OUT OUT GND 1 2 3 4 8 7 6 5 IN IN NC SHDN LT3020EMS8-1.2 LT3020EMS8-1.5 LT3020EMS8-1.8 MS8 PART MARKING LTBKG LTBKH LTBKJ MS8 PACKAGE 8-LEAD PLASTIC MSOP TJMAX = 150°C, θJA = 125°C/ W, θJC = 40°C/ W SEE THE APPLICATIONS INFORMATION SECTION sn3020 3020fas LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TJ = 25°C. PARAMETER CONDITIONS MIN TYP 0.9 0.9 ● ● ● ● ● ● ● ● ● ● ● ● ● MAX 1.05 1.10 204 206 1.224 1.236 1.530 1.545 1.836 1.854 1.75 10.5 13 15.8 1 1 6 6 7.5 7.5 9 9 115 180 180 285 250 UNITS V V mV mV V V V V V V mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV µA µA µA mA µVRMS nA V V µA µA µA dB dB dB dB Minimum Input Voltage (Note 14) ILOAD = 100mA, TJ > 0°C ILOAD = 100mA, TJ < 0°C ADJ Pin Voltage (Notes 4, 5) Regulated Output Voltage (Note 4) VIN = 1.5V, ILOAD = 1mA 1.15V < VIN < 10V, 1mA < ILOAD < 100mA LT3020-1.2 LT3020-1.5 LT3020-1.8 Line Regulation (Note 6) VIN = 1.5V, ILOAD = 1mA 1.5V < VIN < 10V, 1mA < ILOAD < 100mA VIN = 1.8V, ILOAD = 1mA 1.8V < VIN < 10V, 1mA < ILOAD < 100mA VIN = 2.1V, ILOAD = 1mA 2.1V < VIN < 10V, 1mA < ILOAD < 100mA 196 193 1.176 1.157 1.470 1.447 1.764 1.737 –1.75 –10.5 –13 –15.8 –1 –2 –6 –12 –7.5 –15 –9 –18 200 200 1.200 1.200 1.500 1.500 1.800 1.800 0 0 0 0 0.4 1 1.5 2 85 150 ∆VIN = 1.15V to 10V, ILOAD = 1mA LT3020-1.2 ∆VIN = 1.5V to 10V, ILOAD = 1mA LT3020-1.5 ∆VIN = 1.8V to 10V, ILOAD = 1mA LT3020-1.8 ∆VIN = 2.1V to 10V, ILOAD = 1mA VIN = 1.15V, ∆ILOAD = 1mA to 100mA VIN = 1.15V, ∆ILOAD = 1mA to 100mA LT3020-1.2 LT3020-1.5 LT3020-1.8 VIN = 1.5V, ∆ILOAD = 1mA to 100mA VIN = 1.5V, ∆ILOAD = 1mA to 100mA VIN = 1.8V, ∆ILOAD = 1mA to 100mA VIN = 1.8V, ∆ILOAD = 1mA to 100mA VIN = 2.1V, ∆ILOAD = 1mA to 100mA VIN = 2.1V, ∆ILOAD = 1mA to 100mA Load Regulation (Note 6) Dropout Voltage (Notes 7, 12) ILOAD = 10mA ILOAD = 10mA ILOAD = 100mA ILOAD = 100mA ● ● GND Pin Current VIN = VOUT(NOMINAL) (Notes 8, 12) Output Voltage Noise ADJ Pin Bias Current Shutdown Threshold SHDN Pin Current (Note 10) Quiescent Current in Shutdown Ripple Rejection (Note 6) ILOAD = 0mA ILOAD = 1mA ILOAD = 10mA ILOAD = 100mA COUT = 2.2µF, ILOAD = 100mA, BW = 10Hz to 100kHz, VOUT = 1.2V VADJ = 0.2V, RIPPLE = 1.2V (Notes 6, 9) VOUT = Off to On VOUT = On to Off VSHDN = 0V, VIN = 10V VSHDN = 10V, VIN = 10V VIN = 6V, VSHDN = 0V VIN – VOUT = 1V, VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 100mA LT3020-1.2 VIN – VOUT = 1V, VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 100mA LT3020-1.5 VIN – VOUT = 1V, VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 100mA LT3020-1.8 VIN – VOUT = 1V, VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 100mA ● 120 570 920 2.25 245 20 3.5 50 0.9 ±0.3 9.5 9 ● ● ● ● 0.25 0.61 0.61 3 3 64 60 58 56 sn3020 3020fas 3 LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TJ = 25°C. PARAMETER Current Limit (Note 12) Input Reverse Leakage Current Reverse Output Current (Notes 11, 13) CONDITIONS VIN = 10V, VOUT = 0V VIN = VOUT(NOMINAL) + 0.5V, ∆VOUT = – 5% VIN = – 10V, VOUT = 0V VOUT = 1.2V, VIN = 0V LT3020-1.2 VOUT = 1.2V, VIN = 0V LT3020-1.5 VOUT = 1.5V, VIN = 0V LT3020-1.8 VOUT = 1.8V, VIN = 0V MIN ● 110 TYP 360 310 1 3 10 10 10 MAX UNITS mA mA µA µA µA µA µA 10 5 15 15 15 Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT3020 regulators are tested and specified under pulse load conditions such that TJ ≈ TA. The LT3020 is 100% production 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: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. Note 4: Maximum junction temperature limits operating conditions. The regulated output voltage specification does not apply for all possible combinations of input voltage and output current. Limit the output current range if operating at maximum input voltage. Limit the input voltage range if operating at maximum output current. Note 5: Typically the LT3020 supplies 100mA output current with a 1V input supply. The guaranteed minimum input voltage for 100mA output current is 1.10V. Note 6: The LT3020 is tested and specified for these conditions with an external resistor divider (20k and 30.1k) setting VOUT to 0.5V. The external resistor divider adds 10µA of output load current. The line regulation and load regulation specifications refer to the change in the 0.2V reference voltage, not the 0.5V output voltage. Specifications for fixed output voltage devices are referred to the output voltage. 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 equals: (VIN – VDROPOUT). Note 8: GND pin current is tested with VIN = VOUT(NOMINAL) and a current source load. The device is tested while operating in its dropout region. This condition forces the worst-case GND pin current. GND pin current decreases at higher input voltages. Note 9: Adjust pin bias current flows out of the ADJ pin. Note 10: Shutdown pin current flows into the SHDN pin. Note 11: Reverse output current is tested with IN grounded and OUT forced to the rated output voltage. This current flows into the OUT pin and out of the GND pin. For fixed voltage devices this includes the current in the output resistor divider. Note 12: The LT3020 is tested and specified for these conditions with an external resistor divider (20k and 100k) setting VOUT to 1.2V. The external resistor divider adds 10µA of load current. Note 13: Reverse current is higher for the case of (rated_output) < VOUT < VIN, because the no-load recovery circuitry is active in this region and is trying to restore the output voltage to its nominal value. Note 14: Minimum input voltage is the minimum voltage required by the control circuit to regulate the output voltage and supply the full 100mA rated current. This specification is tested at VOUT = 0.5V. At higher output voltages the minimum input voltage required for regulation will be equal to the regulated output voltage VOUT plus the dropout voltage. TYPICAL PERFOR A CE CHARACTERISTICS Typical Dropout Voltage 250 225 DROPOUT VOLTAGE (mV) DROPOUT VOLTAGE (mV) 200 175 150 125 100 75 50 25 0 0 10 20 30 40 50 60 70 80 90 100 OUTPUT CURRENT (mA) 3020 G01 175 150 125 100 75 50 25 0 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 IL = 1mA IL = 10mA IL = 50mA QUIESCENT CURRENT (µA) TJ = 125°C TJ = 25°C 4 UW Dropout Voltage 250 225 200 VOUT = 1.2V IL = 100mA 250 Quiescent Current VIN = 6V 225 VOUT = 1.2V IL = 0 200 175 150 125 100 75 50 25 0 –50 –25 VSHDN = 0V 0 25 50 75 TEMPERATURE (°C) 100 125 VSHDN = VIN 3020 G02 3020 G03 sn3020 3020fas LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 TYPICAL PERFOR A CE CHARACTERISTICS ADJ Pin Voltage 206 204 ADJ PIN VOLTAGE (mV) IL = 1mA OUTPUT VOLTAGE (V) 202 200 198 196 194 –50 1.810 1.800 1.790 1.780 1.770 –50 –25 OUTPUT VOLTAGE (V) –25 0 25 50 75 TEMPERATURE (°C) Output Voltage 1.230 1.220 IL = 1mA 1000 QUIESCENT CURRENT (µA) GND PIN CURRENT (µA) OUTPUT VOLTAGE (V) 1.210 1.200 1.190 1.180 1.170 –50 –25 50 25 75 0 TEMPERATURE (°C) Quiescent Current 1000 900 QUIESCENT CURRENT (µA) VOUT = 1.8V (LT 3020-1.8) IL = 0 TJ = 25°C GND PIN CURRENT (µA) 700 600 500 400 300 200 100 0 0 1 2 VSHDN = VIN VSHDN = 0V 34567 INPUT VOLTAGE (V) 8 9 10 1750 1500 1250 1000 750 500 250 0 0 1 2 QUIESCENT CURRENT (µA) 800 UW 100 3020 G04 Output Voltage 1.830 1.820 IL = 1mA 1.530 1.520 1.510 1.500 1.490 1.480 Output Voltage IL = 1mA 125 50 25 75 0 TEMPERATURE (°C) 100 125 1.470 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 3020 G22 3020 G23 Quiescent Current VOUT = 1.2V 900 IL = 0 TJ = 25°C 800 700 600 500 400 300 200 100 100 125 0 0 1 2 VSHDN = VIN VSHDN = 0V 34567 INPUT VOLTAGE (V) 8 9 10 2500 2250 2000 1750 1500 1250 1000 750 500 250 0 GND Pin Current VOUT = 1.2V TJ = 25°C RL = 12Ω IL = 100mA RL = 24Ω IL = 50mA RL = 120Ω IL = 10mA RL = 1.2k, IL = 1mA 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 3020 G24 3020 G05 3020 G06 GND Pin Current 2500 2250 2000 RL = 18Ω IL = 100mA VOUT = 1.8V (LT 3020-1.8) TJ = 25°C 1000 900 800 700 600 500 400 300 200 100 Quiescent Current VOUT = 1.5V (LT 3020-1.5) IL = 0 TJ = 25°C RL = 36Ω IL = 50mA RL = 180Ω IL = 10mA RL = 1.8k IL = 1mA VSHDN = VIN VSHDN = 0V 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 34567 INPUT VOLTAGE (V) 8 9 10 0 3020 G25 3020 G26 3020 G27 sn3020 3020fas 5 LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 TYPICAL PERFOR A CE CHARACTERISTICS GND Pin Current 2500 2250 2000 VOUT = 1.5V (LT 3020-1.5) TJ = 25°C 1750 1500 1250 1000 750 500 250 0 0 1 GND PIN CURRENT (µA) RL = 15Ω IL = 100mA RL = 30Ω IL = 50mA RL = 150Ω IL = 10mA RL = 1.5k IL = 1mA 1400 1200 1000 800 600 400 200 SHDN PIN THRESHOLD (V) GND PIN CURRENT (µA) 2 34567 INPUT VOLTAGE (V) SHDN Pin Input Current 5.0 4.5 SHDN PIN INPUT CURRENT (µA) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 1 2 345678 SHDN PIN VOLTAGE (V) 9 10 SHDN PIN INPUT CURRENT (µA) TJ = 25°C 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 ADJ PIN BIAS CURRENT (nA) Current Limit 500 450 400 CURRENT LIMIT (mA) VOUT = 0V REVERSE OUTPUT CURRENT (µA) RIPPLE REJECTION (dB) VIN = 10V VIN = 1.7V 350 300 250 200 150 100 50 0 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 6 UW 8 9 GND Pin Current vs ILOAD 2000 VIN = 1.7V 1800 VOUT = 1.2V TJ = 25°C 1600 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 10 20 30 40 50 60 70 80 90 100 OUTPUT CURRENT (mA) 3020 G07 SHDN Pin Threshold IL = 1mA 10 0 0 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 3020 G28 3020 G08 SHDN Pin Input Current (µA) 5.0 4.5 4.0 20 VSHDN = 10V 25 ADJ Pin Bias Current 15 10 5 0 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 3020 G09 3020 G10 3020 G11 Reverse Output Current 500 VIN = 0V 450 VOUT = 1.2V 400 350 300 250 200 150 100 50 0 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 Input Ripple Rejection 70 60 50 40 30 20 10 VIN = 1.5V + 50mVRMS RIPPLE VOUT = 0.5V COUT = 2.2µF I = 100mA 0L 10 1k 10k 1M 100 100k FREQUENCY (Hz) 3020 G14 COUT = 10µF 3020 G12 3020 G13 sn3020 3020fas LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 TYPICAL PERFOR A CE CHARACTERISTICS Input Ripple Rejection 100 90 80 RIPPLE REJECTION (dB) 70 60 50 40 30 20 VIN = 1.5V + 0.5VP-P RIPPLE AT f = 120Hz 10 VOUT = 0.5V IL = 100mA 0 0 25 50 75 100 125 –50 –25 TEMPERATURE (°C) 3020 G15 MINIMUM INPUT VOLTAGE (V) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 LOAD REGULATION (mV) Output Noise Spectral Density OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) 10 VOUT = 1.2V IL = 100mA COUT = 2.2µF 300 250 OUTPUT CURRENT SINK (mA) 1 OUTPUT NOISE (µVRMS) 0.1 0.01 10 100 1k 10k FREQUENCY (Hz) UW 100k Minimum Input Voltage 1.1 1.0 0.9 IL = 100mA 1.0 0.8 0.6 0.4 0.2 0 –0.2 Load Regulation ∆IL = 1mA to 100mA –0.4 V = 1.15V IN –0.6 VOUT = 0.5V *LOAD REGULATION NUMBER REFERS –0.8 TO CHANGE IN THE 200mV REFERENCE VOLTAGE –1.0 0 25 50 75 100 –50 –25 TEMPERATURE (°C) 125 3020 G16 3020 G17 Transient Response VOUT 50mV/DIV IOUT 100mA/DIV 50µs/DIV IOUT = 10mA TO 100mA VOUT = 1.5V 3020 G21 RMS Output Noise vs Load Current (10Hz to 100kHz) VOUT = 1.2V COUT = 2.2µF 18 16 14 12 10 8 6 4 2 No-Load Recovery Threshold 200 150 100 50 0 0.01 1M 3020 G18 0.1 1 10 LOAD CURRENT (mA) 100 3020 G19 0 0 5 10 15 OUTPUT OVERSHOOT (%) 20 3020 G20 sn3020 3020fas 7 LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 PI FU CTIO S OUT (Pins 1, 2): These pins supply power to the load. Use a minimum output capacitor of 2.2µF to prevent oscillations. Applications with large load transients require larger output capacitors to limit peak voltage transients. See the Applications Information section for more information on output capacitance and reverse output characteristics. OUT (Pin 3, Fixed Voltage Device Only): This pin is the sense point for the internal resistor divider. It should be tied directly to the other OUT pins (1, 2) for best results. ADJ (Pin 3, Adjustable Device Only): This pin is the inverting terminal to the error amplifier. Its typical input bias current of 20nA flows out of the pin (see curve of ADJ Pin Bias Current vs Temperature in the Typical Performance Characteristics). The ADJ pin reference voltage is 200mV (referred to GND). GND (Pin 4): Ground. SHDN (Pin 5): The SHDN pin puts the LT3020 into a low power state. Pulling the SHDN pin low turns the output off. Drive the SHDN pin with either logic or an open collector/ drain device with a pull-up resistor. The pull-up resistor supplies the pull-up current to the open collector/drain logic, normally several microamperes, and the SHDN pin current, typically 2.3µA. If unused, connect the SHDN pin to VIN. The LT3020 does not function if the SHDN pin is not connected. IN (Pins 7, 8): These pins supply power to the device. The LT3020 requires a bypass capacitor at IN if it is more than six inches away from the main input filter capacitor. The output impedance of a battery rises with frequency, so include a bypass capacitor in battery-powered circuits. A bypass capacitor in the range of 2.2µF to 10µF suffices. The LT3020 withstands reverse voltages on the IN pin with respect to ground and the OUT pin. In the case of a reversed input, which occurs if a battery is plugged in backwards, the LT3020 acts as if a diode is in series with its input. No reverse current flows into the LT3020 and no reverse voltage appears at the load. The device protects itself and the load. GND (Pin 9, DD8 Package Only): Ground. Solder Pin 9 (the exposed pad) to the PCB. Connect directly to Pin 4 for best performance. BLOCK DIAGRA SHDN (5) SHUTDOWN 200mV BIAS CURRENT AND REFERENCE GENERATOR 212mV – NO-LOAD RECOVERY Q2 R2 25k NOTE: FOR LT3020 ADJUST PIN 3 IS CONNECTED TO THE ADJUST PIN, R1 AND R2 ARE EXTERNAL. FOR LT3020-1.X PIN 3 IS CONNECTED TO THE OUTPUT SENSE PIN, R1 AND R2 ARE INTERNAL. 8 + – W U U U IN (7, 8) THERMAL SHUTDOWN R3 D1 Q3 CURRENT GAIN Q1 ERROR AMP D2 OUT (1, 2) OUT SENSE (3) + ADJ (3) FIXED VOUT 1.2V 1.5V 1.8V R1 R1 R2 GND (4,9) 3020 BD 20k 100k 20k 130k 20k 160k sn3020 3020fas LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 APPLICATIO S I FOR ATIO The LT3020 is a very low dropout linear regulator capable of 1V input supply operation. Devices supply 100mA of output current and dropout voltage is typically 150mV. Quiescent current is typically 120µA and drops to 3µA in shutdown. The LT3020 incorporates several protection features, making it ideal for use in battery-powered systems. The device protects itself against reverse-input and reverse-output voltages. In battery backup applications where the output is held up by a backup battery when the input is pulled to ground, the LT3020 acts as if a diode is in series with its output which prevents reverse current flow. 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 10V without affecting startup or normal operation. Adjustable Operation The LT3020’s output voltage range is 0.2V to 9.5V. Figure 1 shows that the output voltage is set by the ratio of two external resistors. The device regulates the output to maintain the ADJ pin voltage at 200mV referenced to ground. The current in R1 equals 200mV/R1 and the current in R2 is the current in R1 minus the ADJ pin bias current. The ADJ pin bias current of 20nA flows out of the pin. Use the formula in Figure 1 to calculate output voltage. An R1 value of 20k sets the resistor divider current to 10µA. Note that in shutdown the output is turned off and the divider current is zero. Curves of ADJ Pin Voltage vs Temperature and ADJ Pin Bias Current vs Temperature appear in the Typical Performance Characteristics section. IN VIN OUT R2 LT3020-ADJ SHDN GND ADJ + VOUT R1 3020 F01 VOUT = 200mV 1 + R2 – IADJ (R2) R1 VADJ = 200mV IADJ = 20nA AT 25°C OUTPUT RANGE = 0.2V TO 9.5V () Figure 1. Adjustable Operation Specifications for output voltages greater than 200mV are proportional to the ratio of desired output voltage to 200mV; (VOUT/200mV). For example, load regulation for an output current change of 1mA to 100mA is typically U 0.4mV at VADJ = 200mV. At VOUT = 1.5V, load regulation is: (1.5V/200mV) • (0.4mV) = 3mV Output Capacitance and Transient Response The LT3020’s design is stable with a wide range of output capacitors, but is optimized for low ESR ceramic capacitors. The output capacitor’s ESR affects stability, most notably with small value capacitors. Use a minimum output capacitor of 2.2µF with an ESR of 0.3Ω or less to prevent oscillations. The LT3020 is a low voltage device, and output load transient response is a function of output capacitance. Larger values of output capacitance decrease the peak deviations and provide improved transient response for larger load current changes. For output capacitor values greater than 20µF a small feedforward capacitor with a value of 300pF across the upper divider resistor (R2 in Figure 1) is required. Give extra consideration to the use of ceramic capacitors. Manufacturers make ceramic capacitors with a variety of dielectrics, each with a different behavior across temperature and applied voltage. The most common dielectrics are Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics provide high C-V products in a small package at low cost, but exhibit strong voltage and temperature coefficients. The X5R and X7R dielectrics yield highly stable characterisitics and are more suitable for use as the output capacitor at fractionally increased cost. The X5R and X7R dielectrics both exhibit excellent voltage coefficient characteristics. The X7R type works over a larger temperature range and exhibits better temperature stability whereas X5R is less expensive and is available in higher values. Figures 2 and 3 show voltage coefficient and temperature coefficient comparisons between Y5V and X5R material. 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. A ceramic capacitor produced Figure 4’s trace in response to light tapping from a pencil. Similar vibration induced behavior can masquerade as increased output voltage noise. sn3020 3020fas W UU 9 LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 APPLICATIO S I FOR ATIO 20 0 CHANGE IN VALUE (%) 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 3020 F02 Figure 2. Ceramic Capacitor DC Bias Characteristics 40 20 CHANGE IN VALUE (%) 0 –20 –40 –60 –80 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF 50 25 75 0 TEMPERATURE (°C) Y5V X5R –100 –50 –25 100 125 3020 F03 Figure 3. Ceramic Capacitor Temperature Characteristics No-Load/Light-Load Recovery A possible transient load step that occurs is where the output current changes from its maximum level to zero current or a very small load current. The output voltage responds by overshooting until the regulator lowers the amount of current it delivers to the new level. The regulator loop response time and the amount of output capacitance control the amount of overshoot. Once the regulator has decreased its output current, the current provided by the resistor divider (which sets VOUT) is the only current remaining to discharge the output capacitor from the level to which it overshot. The amount of time it takes for the output voltage to recover easily extends to milliseconds with microamperes of divider current and a few microfarads of output capacitance. To eliminate this problem, the LT3020 incorporates a no-load or light-load recovery circuit. This circuit is a 10 U 1mV/DIV VOUT = 1.3V COUT = 10µF ILOAD = 0 1ms/DIV 3020 F04 W UU Figure 4. Noise Resulting from Tapping on a Ceramic Capacitor voltage-controlled current sink that significantly improves the light load transient response time by discharging the output capacitor quickly and then turning off. The current sink turns on when the output voltage exceeds 6% of the nominal output voltage. The current sink level is then proportional to the overdrive above the threshold up to a maximum of approximately 15mA. Consult the curve in the Typical Performance Characteristics for the No-Load Recovery Threshold. If external circuitry forces the output above the no load recovery circuit’s threshold, the current sink turns on in an attempt to restore the output voltage to nominal. The current sink remains on until the external circuitry releases the output. However, if the external circuitry pulls the output voltage above the input voltage, or the input falls below the output, the LT3020 turns the current sink off and shuts down the bias current/reference generator circuitry. Thermal Considerations The LT3020’s power handling capability is limited by its maximum rated junction temperature of 125°C. The power dissipated by the device is comprised of two components: 1. Output current multiplied by the input-to-output voltage differential: (IOUT)(VIN – VOUT) and 2. GND pin current multiplied by the input voltage: (IGND)(VIN). GND pin current is found by examining the GND pin current curves in the Typical Performance Characteristics. Power dissipation is equal to the sum of the two components listed above. sn3020 3020fas LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 APPLICATIO S I FOR ATIO The LT3020 regulator has internal thermal limiting (with hysteresis) designed to protect the device during overload conditions. For normal continuous conditions, do not exceed the maximum junction temperature rating of 125°C. Carefully consider all sources of thermal resistance from junction to ambient including other heat sources mounted in proximity to the LT3020. The underside of the LT3020 DD package has exposed metal (4mm2) from the lead frame to where the die is attached. This allows heat to directly transfer from the die junction to the printed circuit board metal to control maximum operating junction temperature. The dual-in-line pin arrangement allows metal to extend beyond the ends of the package on the topside (component side) of a PCB. Connect this metal to GND on the PCB. The multiple IN and OUT pins of the LT3020 also assist in spreading heat to the PCB. The LT3020 MS8 package has pin 4 fused with the lead frame. This also allows heat to transfer from the die to the printed circuit board metal, therefore reducing the thermal resistance. Copper board stiffeners and plated throughholes 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 for two different packages. Measurements were taken in still air on 3/32" FR-4 board with one ounce copper. Table 1. Measured Thermal Resistance for DD Package COPPER AREA TOPSIDE* BACKSIDE 2500mm2 900mm2 225mm 50mm 2 BOARD AREA 2500mm2 2500mm2 2500mm2 2500mm2 2500mm 2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 35°C/W 40°C/W 55°C/W 60°C/W 70°C/W 2500mm2 2500mm2 2500mm 2500mm 2 100mm2 2 2500mm2 2 Table 2. Measured Thermal Resistance for MS8 Package COPPER AREA TOPSIDE* BACKSIDE 2500mm2 1000mm 225mm 2 2 BOARD AREA 2500mm2 2500mm2 2500mm 2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 110°C/W 115°C/W 120°C/W 130°C/W 140°C/W 2500mm2 2500mm 2500mm 2 2 100mm2 50mm2 2500mm2 2500mm2 2500mm2 2500mm2 *Device is mounted on topside. U Calculating Junction Temperature Example: Given an output voltage of 1.8V, an input voltage range of 2.25V to 2.75V, an output current range of 1mA to 100mA, and a maximum ambient temperature of 70°C, what will the maximum junction temperature be for an application using the DD package? The power dissipated by the device is equal to: IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)) where IOUT(MAX) = 100mA VIN(MAX) = 2.75V IGND at (IOUT = 100mA, VIN = 2.75V) = 3mA so P = 100mA(2.75V – 1.8V) + 3mA(2.75V) = 0.103W The thermal resistance is in the range of 35°C/W to 70°C/W depending on the copper area. So the junction temperature rise above ambient is approximately equal to: 0.103W(52.5°C/W) = 5.4°C The maximum junction temperature equals the maximum junction temperature rise above ambient plus the maximum ambient temperature or: TJMAX = 70°C + 5.4°C = 75.4°C Protection Features The LT3020 incorporates several protection features that make it 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 device also protects against reverseinput voltages, reverse-output voltages and reverse output-to-input voltages. Current limit protection and thermal overload protection protect the device against current overload conditions at the output of the device. For normal operation, do not exceed a junction temperature of 125°C. The IN pins of the device withstand reverse voltages of 10V. The LT3020 limits current flow to less than 1µA and no negative voltage appears at OUT. The device protects both itself and the load against batteries that are plugged in backwards. sn3020 3020fas W UU 11 LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 APPLICATIO S I FOR ATIO The LT3020 incurs no damage if OUT is pulled below ground. If IN is left open circuit or grounded, OUT can be pulled below ground by 10V. No current flows from the pass transistor connected to OUT. However, current flows in (but is limited by) the resistor divider that sets the output voltage. Current flows from the bottom resistor in the divider and from the ADJ pin’s internal clamp through the top resistor in the divider to the external circuitry pulling OUT below ground. If IN is powered by a voltage source, OUT sources current equal to its current limit capability and the LT3020 protects itself by thermal limiting. In this case, grounding SHDN turns off the LT3020 and stops OUT from sourcing current. The LT3020 incurs no damage if the ADJ pin is pulled above or below ground by 10V. If IN is left open circuit or grounded and ADJ is pulled above ground, ADJ acts like a 25k resistor in series with a 1V clamp (one Schottky diode in series with one diode). ADJ acts like a 25k resistor in series with a Schottky diode if pulled below ground. If IN is powered by a voltage source and ADJ is pulled below its reference voltage, the LT3020 attempts to source its current limit capability at OUT. The output voltage increases to VIN – VDROPOUT with VDROPOUT set by whatever load current the LT3020 supports. This condition can potentially damage external circuitry powered by the LT3020 if the output voltage increases to an unregulated high voltage. If IN is powered by a voltage source and ADJ is pulled above its reference voltage, two situations can occur. If ADJ is pulled slightly above its reference voltage, the LT3020 turns off the pass transistor, no output current is sourced and the output voltage decreases to either the voltage at ADJ or less. If ADJ is pulled above its no load recovery threshold, the no load recovery circuitry turns on and attempts to sink current. OUT is actively pulled low and the output voltage clamps at a Schottky diode above ground. Please note that the behavior described above applies to the LT3020 only. If a resistor divider is connected under the same conditions, there will be additional V/R current. 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 12 U circuit. In the case where the input is grounded, there is less than 1µA of reverse output current. If the LT3020 IN pin is forced below the OUT pin or the OUT pin is pulled above the IN pin, input current drops to less than 10µA typically. This occurs if the LT3020 input is connected to a discharged (low voltage) battery and either a backup battery or a second regulator circuit holds up the output. The state of the SHDN pin has no effect on the reverse output current if OUT is pulled above IN. Input Capacitance and Stability The LT3020 is designed to be stable with a minimum capacitance of 2.2µF placed at the IN pin. Ceramic capacitors with very low ESR may be used. However, in cases where a long wire is used to connect a power supply to the input of the LT3020 (and also from the ground of the LT3020 back to the power supply ground), use of low value input capacitors combined with an output load current of 20mA or greater may result in an unstable application. This is due to the inductance of the wire forming an LC tank circuit with the input capacitor and not a result of the LT3020 being unstable. The self-inductance, or isolated inductance, of a wire is directly proportional to its length. However, the diameter of a wire does not have a major influence on its selfinductance. For example, the self inductance of a 2-AWG isolated wire with a diameter of 0.26 in. is about half the inductance of a 30-AWG wire with a diameter of 0.01 in. One foot of 30-AWG wire has 465nH of self inductance. The overall self-inductance of a wire can be reduced in two ways. One is to divide the current flowing towards the LT3020 between two parallel conductors. In this case, the farther the wires are placed apart from each other, the more inductance will be reduced, up to a 50% reduction when placed a few inches apart. Splitting the wires basically connects two equal inductors in parallel. However, when placed in close proximity from each other, mutual inductance is added to the overall self inductance of the wires. The most effective way to reduce overall inductance is to place the forward and return-current conductors (the wire for the input and the wire for ground) in very close proximity. Two 30-AWG wires separated by 0.02 in. reduce the overall self-inductance to about one-fifth of a single isolated wire. sn3020 3020fas W UU LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 APPLICATIO S I FOR ATIO If the LT3020 is powered by a battery mounted in close proximity on the same circuit board, a 2.2µF input capacitor is sufficient for stability. However, if the LT3020 is powered by a distant supply, use a larger value input capacitor following the guideline of roughly 1µF (in addition to the 2.2µF minimum) per 8 inches of wire length. As power supply output impedance may vary, the minimum input capacitance needed to stabilize the application may U also vary. Extra capacitance may also be placed directly on the output of the power supply; however, this will require an order of magnitude more capacitance as opposed to placing extra capacitance in close proximity to the LT3020. Furthermore, series resistance may be placed between the supply and the input of the LT3020 to stabilize the application; as little as 0.1Ω to 0.5Ω will suffice. sn3020 3020fas W UU 13 LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 PACKAGE DESCRIPTIO 0.675 ± 0.05 3.5 ± 0.05 1.65 ± 0.05 2.15 ± 0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ± 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS PIN 1 TOP MARK (NOTE 6) 14 U DD Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) R = 0.115 TYP 5 0.38 ± 0.10 8 3.00 ± 0.10 (4 SIDES) 1.65 ± 0.10 (2 SIDES) (DD8) DFN 1203 0.200 REF 0.75 ± 0.05 4 0.25 ± 0.05 2.38 ± 0.10 (2 SIDES) 1 0.50 BSC 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON TOP AND BOTTOM OF PACKAGE sn3020 3020fas LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 PACKAGE DESCRIPTIO 0.889 ± 0.127 (.035 ± .005) 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 0.42 ± 0.038 (.0165 ± .0015) TYP 0.65 (.0256) BSC DETAIL “A” RECOMMENDED SOLDER PAD LAYOUT 0.18 (.007) SEATING PLANE NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 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 MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 8 7 65 0.52 (.0205) REF 0.254 (.010) DETAIL “A” 0° – 6° TYP 4.90 ± 0.152 (.193 ± .006) 3.00 ± 0.102 (.118 ± .004) (NOTE 4) GAUGE PLANE 1 0.53 ± 0.152 (.021 ± .006) 1.10 (.043) MAX 23 4 0.86 (.034) REF 0.22 – 0.38 (.009 – .015) TYP 0.65 (.0256) BSC 0.127 ± 0.076 (.005 ± .003) MSOP (MS8) 0204 sn3020 3020fas 15 LT3020/LT3020-1.2/ LT3020-1.5/LT3020-1.8 RELATED PARTS PART NUMBER LT1121/LT1121HV LT1129 LT1761 DESCRIPTION 150mA, Micropower LDOs 700mA, Micropower LDO 100mA, Low Noise Micropower LDO COMMENTS VIN: 4.2V to 30V/36V, VOUT(MIN) = 3.75V, VDO = 0.42V, IQ = 30µA, ISD = 16µA, Reverse-Battery Protection, SOT-223, S8, Z Packages VIN: 4.2V to 30V, VOUT(MIN) = 3.75V, VDO = 0.4V, IQ = 50µA, ISD = 16µA, DD, SOT-223, S8, TO220-5, TSSOP20 Packages VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.3V, IQ = 20µA, ISD < 1µA, Low Noise: < 20µVRMS, Stable with 1µF Ceramic Capacitor, ThinSOT Package VIN: 1.8V to 20V, VOUT(MIN) = 1.22V, VDO = 0.3V, IQ = 25µA, ISD < 1µA, Low Noise: