LT1460S3 (SOT-23) Family of Micropower Series References in SOT-23 U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO 3-Lead SOT-23 Package Low Drift: 20ppm/°C Max High Accuracy: 0.2% Max Low Supply Current 20mA Output Current Guaranteed No Output Capacitor Required Reverse-Battery Protection Low PC Board Solder Stress: 0.02% Typ Voltage Options: 2.5V, 3V, 3.3V, 5V and 10V The LT1460 is Also Available in SO-8, 8-Lead MSOP, 8-Lead PDIP and TO-92 Packages. Operating Temperature Range: – 40°C to 85°C U APPLICATIO S ■ ■ ■ ■ Handheld Instruments Precision Regulators A/D and D/A Converters Power Supplies Hard Disk Drives , LTC and LT are registered trademarks of Linear Technology Corporation. U ■ The LT ®1460S3 is a family of SOT-23 micropower series references that combine high accuracy and low drift with low power dissipation and small package size. These series references use curvature compensation to obtain low temperature coefficient, and laser trimmed precision thin-film resistors to achieve high output accuracy. Furthermore, output shift due to PC board soldering stress has been dramatically reduced. These references will supply up to 20mA, making them ideal for precision regulator applications, yet they are almost totally immune to input voltage variations. These series references provide supply current and power dissipation advantages over shunt references that must idle the entire load current to operate. Additionally, the LT1460S3 does not require an output compensation capacitor. This feature is important in applications where PC board space is a premium or fast settling is demanded. Reversebattery protection keeps these references from conducting reverse current. TYPICAL APPLICATIO Typical Distribution of SOT-23 LT1460HC VOUT After IR Reflow Solder 32 Basic Connection 28 LT1460HC LIMITS LT1460S3 VOUT + 0.9V ≤ VIN ≤ 20V IN C1 0.1µF OUT VOUT GND 1460S3 TA01 DISTRIBUTION (%) 24 20 16 12 8 4 0 – 0.3 – 0.2 – 0.1 0.1 0.2 0 OUTPUT VOLTAGE ERROR (%) 0.3 1460S3 TA02 1 LT1460S3 (SOT-23) W W U W ABSOLUTE MAXIMUM RATINGS (Note 1) Input Voltage ........................................................... 30V Reverse Voltage .................................................... – 15V Output Short-Circuit Duration, TA = 25°C .............. 5 sec Specified Temperature Range ..................... 0°C to 70°C Operating Temperature Range (Note 2) ............................................. – 40°C to 85°C Storage Temperature Range (Note 3) ... – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C U W U PACKAGE/ORDER INFORMATION TOP VIEW IN 1 3 GND OUT 2 S3 PACKAGE 3-LEAD PLASTIC SOT-23 TJMAX = 125°C, θJA = 325°C/ W ORDER PART NUMBER S3 PART MARKING LT1460HCS3-2.5 LT1460JCS3-2.5 LT1460KCS3-2.5 LT1460HCS3-3 LT1460JCS3-3 LT1460KCS3-3 LT1460HCS3-3.3 LT1460JCS3-3.3 LT1460KCS3-3.3 LT1460HCS3-5 LT1460JCS3-5 LT1460KCS3-5 LT1460HCS3-10 LT1460JCS3-10 LT1460KCS3-10 LTAC LTAD LTAE LTAN LTAP LTAQ LTAR LTAS LTAT LTAK LTAL LTAM LTAU LTAV LTAW Consult factory for Industrial and Military grade parts. U AVAILABLE OPTIO S OUTPUT VOLTAGE (V) 2.5 2.5 2.5 3 3 3 3.3 3.3 3.3 5 5 5 10 10 10 2 SPECIFIED TEMPERATURE RANGE 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C 0°C to 70°C ACCURACY (%) 0.2 0.4 0.5 0.2 0.4 0.5 0.2 0.4 0.5 0.2 0.4 0.5 0.2 0.4 0.5 TEMPERATURE COEFFICIENT (ppm/°C) 20 20 50 20 20 50 20 20 50 20 20 50 20 20 50 PART ORDER NUMBER LT1460HCS3-2.5 LT1460JCS3-2.5 LT1460KCS3-2.5 LT1460HCS3-3 LT1460JCS3-3 LT1460KCS3-3 LT1460HCS3-3.3 LT1460JCS3-3.3 LT1460KCS3-3.3 LT1460HCS3-5 LT1460JCS3-5 LT1460KCS3-5 LT1460HCS3-10 LT1460JCS3-10 LT1460KCS3-10 LT1460S3 (SOT-23) ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full specified temperature range, otherwise specifications are at TA = 25°C. VIN = VOUT + 2.5V, IOUT = 0 unless otherwise specified. PARAMETER CONDITIONS MIN Output Voltage Tolerance (Note 4) LT1460HCS3 MAX UNITS – 0.2 0.2 % LT1460JCS3 – 0.4 0.4 % LT1460KCS3 – 0.5 0.5 % 10 10 25 20 20 50 ppm/°C ppm/°C ppm/°C 150 800 1000 ppm/V ppm/V 50 100 130 ppm/V ppm/V 1000 3000 4000 ppm/mA ppm/mA 50 200 300 ppm/mA ppm/mA 20 70 100 ppm/mA ppm/mA 2.5 10 ppm/mW ● 0.9 V ● 1.3 1.4 V V Output Voltage Temperature Coefficient (Note 5) LT1460HCS3 LT1460JCS3 LT1460KCS3 Line Regulation VOUT + 0.9V ≤ VIN ≤ VOUT + 2.5V ● ● ● TYP ● VOUT + 2.5V ≤ VIN ≤ 20V ● Load Regulation Sourcing (Note 6) IOUT = 100µA ● IOUT = 10mA ● IOUT = 20mA ● Thermal Regulation (Note 7) Dropout Voltage (Note 8) ∆P = 200mW VIN – VOUT, ∆VOUT ≤ 0.2%, IOUT = 0 VIN – VOUT, ∆VOUT ≤ 0.2%, IOUT = 10mA Output Current Short VOUT to GND Reverse Leakage VIN = – 15V Output Voltage Noise (Note 9) 0.1Hz ≤ f ≤ 10Hz 10Hz ≤ f ≤ 1kHz 40 ● Long-Term Stability of Output Voltage (Note 10) Hysteresis (Note 11) ∆T = 0°C to 70°C ∆T = –40°C to 85°C Supply Current LT1460S3-2.5 ● ● 0.5 ppm (P-P) ppm (RMS) 100 ppm/√kHr 50 250 ppm ppm 115 145 175 µA µA 145 180 220 µA µA 145 180 220 µA µA 160 200 240 µA µA 215 270 350 µA µA ● LT1460S3-3.3 ● LT1460S3-5 ● LT1460S3-10 ● Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1460S3 is guaranteed functional over the operating temperature range of – 40°C to 85°C. Note 3: If the parts are stored outside of the specified temperature range, the output may shift due to hysteresis. µA 4 4 ● LT1460S3-3 mA 10 Note 4: ESD (Electrostatic Discharge) sensitive devices. Extensive use of ESD protection devices are used internal to the LT1460S3, however, high electrostatic discharge can damage or degrade the device. Use proper ESD handling precautions. Note 5: Temperature coefficient is measured by dividing the change in output voltage by the specified temperature range. Incremental slope is also measured at 25°C. 3 LT1460S3 (SOT-23) ELECTRICAL CHARACTERISTICS Note 6: Load regulation is measured on a pulse basis from no load to the specified load current. Output changes due to die temperature change must be taken into account separately. Note 7: Thermal regulation is caused by die temperature gradients created by load current or input voltage changes. This effect must be added to normal line or load regulation. This parameter is not 100% tested. Note 8: Excludes load regulation errors. Note 9: Peak-to-peak noise is measured with a single pole highpass filter at 0.1Hz and 2-pole lowpass filter at 10Hz. The unit is enclosed in a still-air environment to eliminate thermocouple effects on the leads. The test time is 10 sec. RMS noise is measured with a single pole highpass filter at 10Hz and a 2-pole lowpass filter at 1kHz. The resulting output is full wave rectified and then integrated for a fixed period, making the final reading an average as opposed to RMS. A correction factor of 1.1 is used to convert from average to RMS and a second correction of 0.88 is used to correct for the nonideal bandpass of the filters. Note 10: Long-term stability typically has a logarithmic characteristic and therefore, changes after 1000 hours tend to be much smaller than before that time. Total drift in the second thousand hours is normally less than one third that of the first thousand hours with a continuing trend toward reduced drift with time. Long-term stability will also be affected by differential stresses between the IC and the board material created during board assembly. Note 11: Hysteresis in output voltage is created by package stress that differs depending on whether the IC was previously at a higher or lower temperature. Output voltage is always measured at 25°C, but the IC is cycled to 70°C or 0°C before successive measurements. Hysteresis is roughly proportional to the square of the temperature change. Hysteresis is not normally a problem for operational temperature excursions where the instrument might be stored at high or low temperature. See Applications Information. U W TYPICAL PERFORMANCE CHARACTERISTICS Characteristic curves are similar for most LT1460S3s. Curves from the LT1460S3-2.5 and the LT1460-10 represent the extremes of the voltage options. Characteristic curves for other output voltages fall between these curves, and can be estimated based on their voltage output. 2.5V Minimum Input-Output Voltage Differential 2.5V Load Regulation, Sourcing 25°C – 55°C 1 0.1 0 0.5 1.0 1.5 2.0 INPUT-OUTPUT VOLTAGE (V) 2.5 1460S3 G01 – 0.5 OUTPUT VOLTAGE CHANGE (mV) 125°C 10 4 2.5V Load Regulation, Sinking 120 0 OUTPUT VOLTAGE CHANGE (mV) OUTPUT CURRENT (mA) 100 – 1.0 – 55°C – 1.5 – 2.0 25°C – 2.5 125°C – 3.0 – 3.5 – 4.0 0.1 100 80 60 25°C 125°C – 55°C 40 20 0 1 10 OUTPUT CURRENT (mA) 100 1460s3 G02 0 1 2 3 4 OUTPUT CURRENT (mA) 5 1460S3 G03 LT1460S3 (SOT-23) U W TYPICAL PERFORMANCE CHARACTERISTICS Characteristic curves are similar for most LT1460S3s. Curves from the LT1460S3-2.5 and the LT1460-10 represent the extremes of the voltage options. Characteristic curves for other output voltages fall between these curves, and can be estimated based on their voltage output. 2.5V Output Voltage Temperature Drift 250 THREE TYPICAL PARTS 2.502 2.501 2.500 2.499 2.501 25°C 200 SUPPLY CURRENT (µA) OUTPUT VOLTAGE (V) 2.5V Line Regulation 2.502 25°C 125°C – 55°C 150 100 2.500 – 55°C 2.499 2.498 125°C 2.497 2.496 50 2.498 2.495 2.497 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 0 125 2.494 5 0 10 15 2 4 1460S3 G06 2.5V Output Impedance vs Frequency 80 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 1460S3 G05 2.5V Power Supply Rejection Ratio vs Frequency 2.5V Transient Response 1000 CL = 0µF OUTPUT IMPEDANCE (Ω) 60 50 40 30 20 20 LOAD CURRENT (mA) 70 CL = 0.1µF 100 10 CL = 1µF 10 1 0.1 1 200µs/DIV 10 1460S3 G09 CLOAD = 0µF 10 100 FREQUENCY (kHz) 1000 0.1 0.01 0.1 1 10 FREQUENCY (kHz) 100 1460S3 G07 1000 1460S3 G08 2.5V Output Voltage Noise Spectrum 2.5V Output Noise 0.1Hz to 10Hz 1000 OUTPUT NOISE (20µV/DIV) 1 NOISE VOLTAGE (nV/√Hz) 0 0.1 0 20 INPUT VOLTAGE (V) 1460S3 G04 POWER SUPPLY REJECTION RATIO (dB) OUTPUT VOLTAGE (V) 2.503 2.5V Supply Current vs Input Voltage 100 10 100 1k 10k FREQUENCY (Hz) 100k TIME (2 SEC/DIV) 1460-2.5 G10 1460S3 G11 5 LT1460S3 (SOT-23) U W TYPICAL PERFORMANCE CHARACTERISTICS Characteristic curves are similar for most LT1460S3s. Curves from the LT1460S3-2.5 and the LT1460-10 represent the extremes of the voltage options. Characteristic curves for other output voltages fall between these curves, and can be estimated based on their voltage output. 10V Minimum Input-Output Voltage Differential 10V Load Regulation, Sourcing 100 10V Load Regulation, Sinking 35 250 125°C 25°C – 55°C 1 25 20 15 10 5 – 55°C 0 –5 0 0.5 1.0 1.5 2.0 INPUT-OUTPUT VOLTAGE (V) 125°C –10 0.1 0.1 2.5 10V Output Voltage Temperature Drift 10.004 25°C 100 –55°C 50 0 100 1 0 3 4 2 OUTPUT CURRENT (mA) 10V Line Regulation 10.010 350 THREE TYPICAL PARTS 300 SUPPLY CURRENT (µA) 10.000 9.998 9.996 9.994 9.992 9.990 9.988 9.986 5 1460S3 G14 10V Supply Current vs Input Voltage 10.002 OUTPUT VOLTAGE (V) 125°C 150 1460S3 G13 1460S3 G12 10.006 200 25°C 1 10 OUTPUT CURRENT (mA) 10.005 25°C 250 125°C – 55°C 200 150 100 OUTPUT VOLTAGE (V) 10 OUTPUT VOLTAGE CHANGE (mV) OUTPUT VOLTAGE CHANGE (mV) OUTPUT CURRENT (mA) 30 25°C 10.000 – 55°C 9.995 125°C 9.990 9.985 50 9.984 9.982 – 50 – 25 50 25 0 75 TEMPERATURE (°C) 9.980 0 125 100 0 2 4 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) 1460S3 G15 20 10V Transient Response 20 OUTPUT IMPEDANCE (Ω) 70 60 50 40 30 20 LOAD CURRENT (mA) CL = 0µF 80 100 CL = 0.1µF 10 CL = 1µF 10 1 0.1 1 200µs/DIV 10 CLOAD = 0µF 1 10 100 FREQUENCY (kHz) 1000 1460S3 G18 6 18 1000 90 0 0.1 14 12 16 10 INPUT VOLTAGE (V) 1560S3 G17 10V Output Impedance vs Frequency 100 8 1460S3 G16 10V Power Supply Rejection Ratio vs Frequency POWER SUPPLY REJECTION RATIO (dB) 6 0.1 0.01 0.1 1 10 FREQUENCY (kHz) 100 1000 1460S3 G19 1460S3 G20 LT1460S3 (SOT-23) U W TYPICAL PERFORMANCE CHARACTERISTICS Characteristic curves are similar for most LT1460S3s. Curves from the LT1460S3-2.5 and the LT1460-10 represent the extremes of the voltage options. Characteristic curves for other output voltages fall between these curves, and can be estimated based on their voltage output. 10V Output Voltage Noise Spectrum 10V Output Noise 0.1Hz to 10Hz OUTPUT NOISE (20µV/DIV) NOISE VOLTAGE (µV/√Hz) 10 1 0.1 0.01 0.1 1 10 FREQUENCY (kHz) 100 TIME (2 SEC/DIV) 1460S3 G10 1460S3 G22 U W U U APPLICATIONS INFORMATION Longer Battery Life Series references have a large advantage over older shunt style references. Shunt references require a resistor from the power supply to operate. This resistor must be chosen to supply the maximum current that can ever be demanded by the circuit being regulated. When the circuit being controlled is not operating at this maximum current, the shunt reference must always sink this current, resulting in high dissipation and short battery life. The LT1460S3 series references do not require a current setting resistor and can operate with any supply voltage from VOUT + 0.9V to 20V. When the circuitry being regulated does not demand current, the LT1460S3s reduce their dissipation and battery life is extended. If the references are not delivering load current, they dissipate only several mW, yet the same connection can deliver 20mA of load current when demanded. Capacitive Loads The LT1460S3 family of references are designed to be stable with a large range of capacitive loads. With no capacitive load, these references are ideal for fast settling or applications where PC board space is a premium. The test circuit shown in Figure 1 is used to measure the response time and stability of various load currents and load capacitors. This circuit is set for the 2.5V option. For other voltage options, the input voltage must be scaled up and the output voltage generator offset voltage must be adjusted. The 1V step from 2.5V to 1.5V produces a current step of 10mA or 1mA for RL = 100Ω or RL = 1k. Figure 2 shows the response of the reference to these 1mA and 10mA load steps with no load capacitance, and Figure 3 shows a 1mA and 10mA load step with a 0.1µF output capacitor. Figure 4 shows the response to a 1mA load step with CL = 1µF and 4.7µF. VIN = 2.5V CIN 0.1µF LT1460S3-2.5 RL VOUT VGEN CL 2.5V 1.5V 1460S3 F01 Figure 1. Response Time Test Circuit 7 LT1460S3 (SOT-23) U W U U APPLICATIONS INFORMATION 2.5V VGEN 1.5V VOUT 1mA VOUT 10mA Table 1 gives the maximum output capacitance for various load currents and output voltages to avoid instability. Load capacitors with low ESR (effective series resistance) cause more ringing than capacitors with higher ESR such as polarized aluminum or tantalum capacitors. Table 1. Maximum Output Capacitance 1µs/DIV IOUT = 1mA IOUT = 10mA IOUT = 20mA 2.5V >10µF >10µF 2µF 0.68µF 3V >10µF >10µF 2µF 0.68µF 3.3V >10µF >10µF 1µF 0.68µF 5V >10µF >10µF 1µF 0.68µF 10V >10µF 1µF 0.15µF 0.1µF 1460S3 F02 Figure 2. CL = 0µF VGEN 2.5V 1.5V VOUT 1mA VOUT 10mA 100µs/DIV VOLTAGE OPTION IOUT = 100µA 1460S3-5 F03 Figure 3. CL = 0.1µF VGEN Long-Term Drift Long-term drift cannot be extrapolated from accelerated high temperature testing. This erroneous technique gives drift numbers that are widely optimistic. The only way long-term drift can be determined is to measure it over the time interval of interest. The LT1460S3 long-term drift data was taken on over 100 parts that were soldered into PC boards similar to a “real world” application. The boards were then placed into a constant temperature oven with TA = 30°C, their outputs were scanned regularly and measured with an 8.5 digit DVM. Figure 5 shows typical long-term drift of the LT1460S3s. 2.5V 1.5V 150 VOUT 1µF 100 VOUT 4.7µF ppm 50 100µs/DIV Figure 4. IOUT = 1mA 1460S3 F04 0 – 50 –100 –150 0 100 200 300 400 500 600 700 800 900 1000 HOURS 1460S3 F05 Figure 5. Typical Long-Term Drift 8 LT1460S3 (SOT-23) U W U U APPLICATIONS INFORMATION Hysteresis Hysteresis data shown in Figure 5 and Figure 6 represents the worst-case data taken on parts from 0°C to 70°C and from – 40°C to 85°C. The output is capable of dissipating relatively high power, i.e., for the LT1460S3-2.5, PD = 17.5V • 20mA = 350mW. The thermal resistance of the SOT-23 package is 325°C/W and this dissipation causes a 114°C internal rise producing a junction temperature of TJ = 25°C + 114°C = 139°C. This elevated temperature will cause the output to shift due to thermal hysteresis. For highest performance in precision applications, do not let the LT1460S3’s junction temperature exceed 85°C. 18 16 WORST-CASE HYSTERESIS ON 40 UNITS NUMBER OF UNITS 14 Fast Turn-On It is recommended to add a 0.1µF or larger bypass capacitor to the input pin of the LT1460S3s. Although this can help stability with large load currents, another reason is for proper start-up. The LT1460S3 can start in 10µs, but it is important to limit the dv/dt of the input. Under light load conditions and with a very fast input, internal nodes overslew and this requires finite recovery time. Figure 8 shows the result of no bypass capacitance on the input and no output load on the LT1460S3-5. In this case the supply dv/dt is 7.5V in 30ns which causes internal overslew, and the output does not bias to 5V until 40µs after turn-on. Although 40µs is a typical turn-on time, it can be much longer. Figure 9 shows the effect of a 0.1µF bypass capacitor which limits the input dv/dt to approximately 7.5V in 20µs. The part always starts quickly. 12 10 70°C TO 25°C 0°C TO 25°C 8 6 7.5V VIN 4 0V 2 0 –240 –200 –160 –120 – 80 –40 0 40 HYSTERESIS (ppm) 80 120 160 200 240 VOUT 1460S3 F06 0V Figure 6. 0°C to 70°C Hysteresis 20µs/DIV 9 8 1460S3 F08 Figure 8. CIN = 0µF WORST-CASE HYSTERESIS ON 34 UNITS NUMBER OF UNITS 7 85°C TO 25°C –40°C TO 25°C 6 5 7.5V VIN 4 0V 3 2 1 VOUT 0 –600 –500 –400 –300 –200 –100 0 100 200 300 400 500 600 HYSTERESIS (ppm) 1460S3 F07 Figure 7. – 40°C to 85°C Hysteresis 20µs/DIV 1460S3 F08 Figure 9. CIN = 0.1µF 9 LT1460S3 (SOT-23) U W U U APPLICATIONS INFORMATION Output Accuracy Like all references, either series or shunt, the error budget of the LT1460S3s is made up of primarily three components: initial accuracy, temperature coefficient and load regulation. Line regulation is neglected because it typically contributes only 150ppm/V. The LT1460S3s typically shift 0.02% when soldered into a PCB, so this is also neglected. The output errors are calculated as follows for a 100µA load and 0°C to 70°C temperature range: LT1460HCS3 Initial Accuracy = 0.2% For IOUT = 100µA ∆VOUT = (4000ppm/mA)(0.1mA) = 0.04% For Temperature 0°C to 70°C the maximum ∆T = 70°C ∆VOUT = (20ppm/°C)(70°C) = 0.14% 10 Total worst-case output error is: 0.2% + 0.04% + 0.14% = 0.380% Table 2 gives the worst-case accuracy for LT1460HCS3, LT1460JCS3 and LT1460KCS3 from 0°C to 70°C, and shows that if the LT1460HCS3 is used as a reference instead of a regulator, it is capable of 8 bits of absolute accuracy over temperature without a system calibration. Table 2. Worst-Case Output Accuracy over Temperature IOUT LT1460HCS3 LT1460JCS3 LT1460KCS3 0µA 0.340% 0.540% 0.850% 100µA 0.380% 0.580% 0.890% 10mA 0.640% 0.840% 1.15% 20mA 0.540% 0.740% 1.05% LT1460S3 (SOT-23) U PACKAGE DESCRIPTION Dimensions in millimeters (inches) unless otherwise noted. S3 Package 3-Lead Plastic SOT-23 (LTC DWG # 05-08-1631) 2.80 – 3.04 (0.110 – 0.120) 0.95 0.037 BSC 1.92 0.075 BSC 0.45 – 0.60 (0.017 – 0.024) 2.10 – 2.64 (0.083 – 0.104) 1.20 – 1.40 (0.047 – 0.060) REF 0.55 (0.022) 0.09 – 0.18 (0.004 – 0.007) 0.013 – 0.10 (0.0005 – 0.004) 0.89 – 1.12 (0.035 – 0.044) 0.37 – 0.51 (0.015 – 0.020) SOT-23 0599 NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DIMENSIONS ARE INCLUSIVE OF PLATING 3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 4. MOLD FLASH SHALL NOT EXCEED 0.254mm 5. JEDEC REFERENCE IS TO-236 VARIATION AB 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. 11 LT1460S3 (SOT-23) U TYPICAL APPLICATIONS Handling Higher Load Currents V+ 40mA + 47µF IN R1* LT1460S3 10mA VOUT OUT GND RL TYPICAL LOAD CURRENT = 50mA *SELECT R1 TO DELIVER 80% OF TYPICAL LOAD CURRENT. LT1460 WILL THEN SOURCE AS NECESSARY TO MAINTAIN PROPER OUTPUT. DO NOT REMOVE LOAD AS OUTPUT WILL BE DRIVEN UNREGULATED HIGH. LINE REGULATION IS DEGRADED IN THIS APPLICATION Boosted Output Current with No Current Limit V + ≥ (VOUT + 1.8V) V + – VOUT 40mA 1460S3 TA05 Boosted Output Current with Current Limit V+ ≥ VOUT + 2.8V + R1 220Ω R1 = D1* LED 47µF + R1 220Ω 47µF 8.2Ω 2N2905 2N2905 IN IN LT1460S3 VOUT 100mA OUT GND + LT1460S3 OUT 2µF SOLID TANT 1460S3 TA03 GND + VOUT 100mA 2µF SOLID TANT * GLOWS IN CURRENT LIMIT, DO NOT OMIT 1460S3 TA04 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1019 Precision Bandgap Reference 0.05% Max, 5ppm/°C Max LT1027 Precision 5V Reference 0.02%, 2ppm/°C Max LT1236 Precision Low Noise Reference 0.05% Max, 5ppm/°C Max, SO Package LT1461 Micropower Precision Low Dropout 0.04% Max, 3ppm/°C Max, 50mA Output Current LT1634 Micropower Precision Shunt Reference 1.25V, 2.5V Output 0.05%, 25ppm/°C Max LTC1798 Micropower Low Dropout Reference, Fixed or Adjustable 0.15% Max, 40ppm/°C, 6.5µA Max Supply Current 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417● (408) 432-1900 FAX: (408) 434-0507● TELEX: 499-3977 ● www.linear-tech.com 1460s3f LT/TP 0999 4K • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1997