LTC6652 Precision Low Drift Low Noise Buffered Reference Features n n n n n n n n n n n Description Low Drift: A-Grade 5ppm/°C Max B-Grade 10ppm/°C Max (MSOP8) B-Grade 8ppm/°C Max (LS8) High Accuracy: A Grade ±0.05% Max B-Grade ±0.1% Max Low Noise: 2.1ppmP-P (0.1Hz to 10Hz) 100% Tested at –40°C, 25°C and 125°C Sinks and Sources Current: ±5mA Low Power Shutdown: <2µA Maximum Thermal Hysteresis (LS8): 45ppm (–40°C to 125°C) Long-Term Drift (LS8): 20ppm/√kHr Low Dropout: 300mV Available Output Voltage Options: 1.25V, 2.048V, 2.5V, 3V, 3.3V, 4.096V, 5V 8-Lead MSOP and 5mm × 5mm Surface Mount Hermetic Packages Applications n n n n n n Automotive Control and Monitoring High Temperature Industrial High Resolution Data Acquisition Systems Instrumentation and Process Control Precision Regulators Medical Equipment The LTC®6652 family of precision, low drift, low noise references is fully specified over the temperature range of –40°C to 125°C. High order curvature compensation allows these references to achieve a low drift of less than 5ppm/°C with a predictable temperature characteristic and an output voltage accuracy of ±0.05%. The performance over temperature should appeal to automotive, high performance industrial and other high temperature applications. The LTC6652 voltage references can be powered from supply voltages up to 13.2V. They boast low noise, excellent load regulation, source and sink capability and exceptional line rejection, making them a superior choice for demanding precision applications. A shutdown mode allows power consumption to be reduced when the reference is not needed. The optional output capacitor can be left off when space constraints are critical. The LTC6652 references are offered in an 8-lead MSOP package and an 8-lead LS8 package. The LS8 is a 5mm × 5mm surface mount hermetic package that provides outstanding stability. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical Application Output Voltage Temperature Drift 0.050 2.8V ≤ VIN ≤ 13.2V CIN 0.1µF (OPTIONAL) VIN SHDN VOUT 2.5V LTC6652-2.5 VOUT GND COUT 1µF (OPTIONAL) 6652 TA01a VOUT ACCURACY (%) Basic Connection 0.025 0 –0.025 –0.050 –40 –20 0 20 40 60 80 TEMPERATURE (°C) 100 125 6652 TA01b 6652fe For more information www.linear.com/6652 1 LTC6652 Absolute Maximum Ratings (Note 1) Input Voltage VIN to GND........................................... –0.3V to 13.2V SHDN to GND.............................–0.3V to (VIN + 0.3V) Output Voltage VOUT............................................–0.3V to (VIN + 0.3V) Output Short-Circuit Duration....................... Indefinite Operating Temperature Range................. –40°C to 125°C Storage Temperature Range (Note 2)...... –65°C to 150°C Lead Temperature Range (Soldering, 10 sec) (Note 9)............................................................. 300°C Pin Configuration TOP VIEW GND* TOP VIEW DNC 1 8 GND* VIN 2 7 GND* SHDN 3 6 VOUT GND 4 5 GND* MS8 PACKAGE 8-LEAD PLASTIC MSOP DNC 1 VIN 2 SHDN 3 8 4 7 GND* 6 VOUT 5 GND* GND LS8 PACKAGE 8-PIN LEADLESS CHIP CARRIER (5mm × 5mm) TJMAX = 150°C, θJA = 200°C/W DNC: DO NOT CONNECT *CONNECT THE PINS TO DEVICE GND (PIN 4) TJMAX = 150°C, θJA = 120°C/W DNC: DO NOT CONNECT *CONNECT THE PINS TO DEVICE GND (PIN 4) Order Information LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LTC6652AHMS8-1.25#PBF LTC6652AHMS8-1.25#TRPBF LTCVH 8-Lead Plastic MSOP –40°C to 125°C LTC6652BHMS8-1.25#PBF LTC6652BHMS8-1.25#TRPBF LTCVH 8-Lead Plastic MSOP –40°C to 125°C LTC6652AHMS8-2.048#PBF LTC6652AHMS8-2.048#TRPBF LTCVJ 8-Lead Plastic MSOP –40°C to 125°C LTC6652BHMS8-2.048#PBF LTC6652BHMS8-2.048#TRPBF LTCVJ 8-Lead Plastic MSOP –40°C to 125°C LTC6652AHMS8-2.5#PBF LTC6652AHMS8-2.5#TRPBF LTCQV 8-Lead Plastic MSOP –40°C to 125°C LTC6652BHMS8-2.5#PBF LTC6652BHMS8-2.5#TRPBF LTCQV 8-Lead Plastic MSOP –40°C to 125°C LTC6652AHMS8-3#PBF LTC6652AHMS8-3#TRPBF LTCVK 8-Lead Plastic MSOP –40°C to 125°C LTC6652BHMS8-3#PBF LTC6652BHMS8-3#TRPBF LTCVK 8-Lead Plastic MSOP –40°C to 125°C LTC6652AHMS8-3.3#PBF LTC6652AHMS8-3.3#TRPBF LTCVM 8-Lead Plastic MSOP –40°C to 125°C LTC6652BHMS8-3.3#PBF LTC6652BHMS8-3.3#TRPBF LTCVM 8-Lead Plastic MSOP –40°C to 125°C LTC6652AHMS8-4.096#PBF LTC6652AHMS8-4.096#TRPBF LTCVN 8-Lead Plastic MSOP –40°C to 125°C LTC6652BHMS8-4.096#PBF LTC6652BHMS8-4.096#TRPBF LTCVN 8-Lead Plastic MSOP –40°C to 125°C LTC6652AHMS8-5#PBF LTC6652AHMS8-5#TRPBF LTCVP 8-Lead Plastic MSOP –40°C to 125°C LTC6652BHMS8-5#PBF LTC6652BHMS8-5#TRPBF LTCVP 8-Lead Plastic MSOP –40°C to 125°C 6652fe 2 For more information www.linear.com/6652 LTC6652 order information LEAD FREE FINISH PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LTC6652AHLS8-2.5#PBF † 665225 8-Lead Ceramic LCC 5mm × 5mm –40°C to 125°C LTC6652BHLS8-2.5#PBF † 665225 8-Lead Ceramic LCC 5mm × 5mm –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ † This product is only offered in trays. For more information go to: http://www.linear.com/packaging/ Available Options OUTPUT VOLTAGE INITIAL ACCURACY TEMPERATURE COEFFICIENT PART NUMBER** 1.250 0.05% 0.1% 5ppm/°C 10ppm/°C LTC6652AHMS8-1.25 LTC6652BHMS8-1.25 2.048 0.05% 0.1% 5ppm/°C 10ppm/°C LTC6652AHMS8-2.048 LTC6652BHMS8-2.048 2.500 0.05% 0.1% 0.05% 0.1% 5ppm/°C 10ppm/°C 5ppm/°C 8ppm/°C LTC6652AHMS8-2.5 LTC6652BHMS8-2.5 LTC6652AHLS8-2.5 LTC6652BHLS8-2.5 3.000 0.05% 0.1% 5ppm/°C 10ppm/°C LTC6652AHMS8-3 LTC6652BHMS8-3 3.300 0.05% 0.1% 5ppm/°C 10ppm/°C LTC6652AHMS8-3.3 LTC6652BHMS8-3.3 4.096 0.05% 0.1% 5ppm/°C 10ppm/°C LTC6652AHMS8-4.096 LTC6652BHMS8-4.096 5.000 0.05% 0.1% 5ppm/°C 10ppm/°C LTC6652AHMS8-5 LTC6652BHMS8-5 **See Order Information section for complete part number listing. Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VIN = VOUT + 0.5V, unless otherwise noted. PARAMETER CONDITIONS Output Voltage LTC6652A LTC6652B Output Voltage Temperature Coefficient (Note 3) LTC6652A LTC6652BMS8 LTC6652BLS8 Line Regulation VOUT + 0.5V ≤ VIN ≤ 13.2V, SHDN = VIN Load Regulation (Note 4) MIN TYP –0.05 –0.1 ISOURCE = 5mA, LTC6652-1.25, LTC6652-2.048, LTC6652-2.5, LTC6652-3, LTC6652-3.3, LTC6652-4.096, LTC6652-5 ISINK = 1mA, LTC6652-1.25, LTC6652-2.048 ISINK = 5mA, LTC6652-2.5, LTC6652-3, LTC6652-3.3, LTC6652-4.096, LTC6652-5 l l UNITS 0.05 0.1 % % 2 4 4 5 10 8 ppm/°C ppm/°C ppm/°C 2 50 80 ppm/V ppm/V 20 75 200 ppm/mA ppm/mA 80 250 600 ppm/mA ppm/mA 50 150 450 ppm/mA ppm/mA l l l l MAX 6652fe For more information www.linear.com/6652 3 LTC6652 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VIN = VOUT + 0.5V, unless otherwise noted. PARAMETER CONDITIONS Minimum Operating Voltage (Note 5) ISOURCE = 5mA, VOUT Error ≤ 0.1% LTC6652-1.25, LTC6652-2.048 LTC6652-2.5, LTC6652-3, LTC6652-3.3, LTC6652-4.096, LTC6652-5 MIN l l Output Short-Circuit Current Short VOUT to GND Short VOUT to VIN Shutdown Pin (SHDN) Logic High Input Voltage Logic High Input Current l l Logic Low Input Voltage Logic Low Input Current l l Supply Current TYP MAX V V 2.7 VOUT + 0.3V 16 16 2 mA mA 0.1 1 V µA 0.1 0.8 1 V µA 560 µA µA 2 µA 350 No Load UNITS l 0.1 Shutdown Current SHDN Tied to GND Output Voltage Noise (Note 6) 0.1Hz ≤ f ≤ 10Hz LTC6652-1.25 LTC6652-2.048, LTC6652-2.5, LTC6652-3 LTC6652-3.3 LTC6652-4.096 LTC6652-5 10Hz ≤ f ≤ 1kHz 2.4 2.1 2.2 2.3 2.8 3 ppmP-P ppmP-P ppmP-P ppmP-P ppmP-P ppmRMS Turn-On Time 0.1% Settling, CLOAD = 0 100 µs Long-Term Drift of Output Voltage (Note 7) LTC6652MS8 LTC6652LS8 60 20 ppm/√kHr ppm/√kHr Hysteresis (Note 8) 80 75 45 45 25 10 ppm ppm ppm ppm ppm ppm l ∆T = –40°C to 125°C, LTC6652MS8 ∆T = –40°C to 85°C, LTC6652MS8 ∆T = 0°C to 70°C, LTC6652MS8 ∆T = –40°C to 125°C, LTC6652LS8 ∆T = –40°C to 85°C, LTC6652LS8 ∆T = 0°C to 70°C, LTC6652LS8 Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: If the parts are stored outside of the specified temperature range, the output may shift due to hysteresis. Note 3: Temperature coefficient is measured by dividing the maximum change in output voltage by the specified temperature range. Note 4: 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 5: Excludes load regulation errors. Note 6: Peak-to-peak noise is measured with a 3-pole highpass at 0.1Hz and 4-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 seconds. RMS noise is measured on a spectrum analyzer in a shielded environment where the intrinsic noise of the instrument is removed to determine the actual noise of the device. Note 7: 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 8: 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 the hot or cold temperature limit before successive measurements. Hysteresis is roughly proportional to the square of the temperature change. For instruments that are stored at well controlled temperatures (within 20 or 30 degrees of operational temperature) it’s usually not a dominant error source. Typical hysteresis is the worst-case of 25°C to cold to 25°C or 25°C to hot to 25°C, preconditioned by one thermal cycle. Note 9: The stated temperature is typical for soldering of the leads during manual rework. For detailed IR reflow recommendations, refer to the Applications section. 6652fe 4 For more information www.linear.com/6652 LTC6652 Typical Performance Characteristics Characteristic curves are similar for most LTC6652s. Curves from the LTC6652-1.25, LTC6652-2.5 and the LTC6652-5 represent the extremes and typical of the voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 1.25V Output Voltage Temperature Drift 1.2510 1.25V Line Regulation 1.25V Load Regulation (Sourcing) 1.2506 3 TYPICAL PARTS 0 1.2500 1.2495 125°C 1.2502 1.2500 25°C 1.2498 –40°C 1.2496 1.2490 –80 80 40 0 TEMPERATURE (°C) –40 1.2494 160 120 OUTPUT VOLTAGE CHANGE (ppm) 1.2505 OUTPUT VOLTAGE (V) REFERENCE VOLTAGE (V) 1.2504 0 2 8 6 10 4 INPUT VOLTAGE (V) 12 25°C –100 125°C –150 –200 –250 14 10 1 OUTPUT CURRENT (mA) 0.1 6652 G18 6652 G17 6652 G19 1.25V Low Frequency 0.1Hz to 10Hz Transient Noise 1.25V Load Regulation (Sinking) 1.25V Output Voltage Noise Spectrum 400 400 350 125°C 250 200 25°C 150 100 NOISE VOLTAGE (nV/√Hz) 300 OUTPUT NOISE (1µV/DIV) OUTPUT VOLTAGE CHANGE (ppm) –40°C –50 –40°C 300 200 100 50 0 0.1 1 OUTPUT CURRENT (mA) 10 0 0.01 TIME (1 SECOND/DIV) 6652 G20 0.1 1 FREQUENCY (kHz) 10 6652 G22 6652 G21 1.25 Sinking Current Without Output Capacitor 1.25V Stability with Output Capacitance 1.25 Sinking Current with Output Capacitor 10µF IOUT 0mA VOUT 500mV/DIV 1mA 1µF 0mA OUTPUT CAPACITOR IOUT 1mA VOUT 500mV/DIV COUT = 0µF 500µs/DIV 6652 G23 COUT = 1µF 500µs/DIV 6652 G24 0.1µF 10nF REGION OF MARGINAL STABILITY 1nF 100pF NO CAP –5 –1 0 LOAD CURRENT (mA) 5 6652 G16 6652fe For more information www.linear.com/6652 5 LTC6652 Typical Performance Characteristics Characteristic curves are similar for most LTC6652s. Curves from the LTC6652-1.25, LTC6652-2.5 and the LTC6652-5 represent the extremes and typical of the voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 2.5V Output Voltage Temperature Drift 2.5V Load Regulation (Sourcing) 0 2.5010 3 TYPICAL PARTS OUTPUT VOLTAGE CHANGE (ppm) –20 2.5005 2.5005 OUTPUT VOLTAGE (V) REFERENCE VOLTAGE (V) 2.5010 2.5V Line Regulation 2.5000 2.4995 2.4990 2.5000 125°C 25°C 2.4995 –40°C 2.4990 2.4985 2.4985 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 2.4980 0 2 8 6 10 4 INPUT VOLTAGE (V) 12 6652 G01 125°C 25°C –40°C 6652 G03 0.9 800 0.8 700 600 500 125°C 25°C 400 300 –40°C 0 0.7 0.6 0.5 125°C 0.4 0.3 0.2 100 10 25°C 0.1 0 2 10 1 OUTPUT CURRENT (mA) 0.1 2.5V Shutdown Current vs Input Voltage 8 6 4 10 INPUT VOLTAGE (V) 12 0 14 –40°C 0 2 8 6 4 10 INPUT VOLTAGE (V) 6652 G05 6652 G04 2.5V Minimum VIN-VOUT Differential (Sourcing) 12 14 6652 G06 2.5V Minimum VOUT-VIN Differential (Sinking) 10 OUTPUT CURRENT (mA) 10 OUTPUT CURRENT (mA) –180 1.0 200 1 0.1 –160 SUPPLY CURRENT (µA) 400 1 OUTPUT CURRENT (mA) –140 900 SUPPLY CURRENT (µA) OUTPUT VOLTAGE CHANGE (ppm) 500 0.1 –120 1000 600 0 125°C –100 2.5V Supply Current vs Input Voltage 700 100 25°C –80 6652 G02 2.5V Load Regulation (Sinking) 200 –60 –200 14 –40°C –40 25°C 1 25°C 125°C, –40°C 125°C 0.01 0.001 0.01 0.1 1 0.1 0.001 INPUT-OUTPUT VOLTAGE (V) 6652 G09 –40°C 0.01 0.1 OUTPUT-INPUT VOLTAGE (V) 1 6652 G10 6652fe 6 For more information www.linear.com/6652 LTC6652 Typical Performance Characteristics Characteristic curves are similar for most LTC6652s. Curves from the LTC6652-1.25, LTC6652-2.5 and the LTC6652-5 represent the extremes and typical of the voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 2.5V Low Frequency 0.1Hz to 10Hz Transient Noise 2.5V Output Voltage Noise Spectrum 600 NOISE VOLTAGE (nV/√Hz) OUTPUT NOISE (1µV/DIV) 500 400 300 200 100 0 0.01 TIME (1 SECOND/DIV) 0.1 1 FREQUENCY (kHz) 6652 G12 6652 G11 Stability with Output Capacitance (LTC6652-2.5, LTC6652-3, LTC6652-3.3, LTC6652-4.096, LTC6652-5) Typical VOUT Distribution for LTC6652-2.5 180 10µF 1004 UNITS 160 1µF LTC6652A LIMITS OUTPUT CAPACITOR NUMBER OF UNITS 140 120 80 60 40 0.1µF 10nF REGION OF MARGINAL STABILITY 1nF 100pF 20 0 2.4985 10 2.5005 2.4995 OUTPUT VOLTAGE (V) 2.5015 NO CAP 6652 G15 –5 0 LOAD CURRENT (mA) 5 6652 G14 6652fe For more information www.linear.com/6652 7 LTC6652 Typical Performance Characteristics Characteristic curves are similar for most LTC6652s. Curves from the LTC6652-1.25, LTC6652-2.5 and the LTC6652-5 represent the extremes and typical of the voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 5V Output Voltage Temperature Drift 5.002 3 TYPICAL PARTS 5.000 4.998 800 5.001 SUPPLY CURRENT (µA) 5.003 1000 900 OUTPUT VOLTAGE (V) REFERENCE VOLTAGE (V) 5.005 5V Supply Current vs Input Voltage 5V Line Regulation 25°C 5.000 125°C 4.999 700 600 500 125°C 400 25°C 300 –40°C 200 –40°C 100 4.995 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 4.998 0 8 6 10 4 INPUT VOLTAGE (V) 2 5V Shutdown Current vs Input Voltage 0 0 2 8 6 4 10 INPUT VOLTAGE (V) 14 12 6652 G27 5V Minimum VIN to VOUT Differential (Sourcing) 5V Low Frequency 0.1Hz to 10Hz Transient Noise 10 1.0 0.9 0.7 0.6 0.5 0.4 0.3 –40°C 0.2 OUTPUT NOISE (5µV/DIV) OUTPUT CURRENT (mA) 125°C 0.8 SUPPLY CURRENT (µA) 14 6652 G26 6652 G25 1 25°C 0.1 –40°C 0.1 0 12 125°C 25°C 0 2 8 6 4 10 INPUT VOLTAGE (V) 12 14 0.01 0.001 0.01 0.1 1 TIME (1 SECOND/DIV) INPUT-OUTPUT VOLTAGE (V) 6652 G30 6652 G29 6652 G31 5V Start-Up Response Without Output Capacitor 5V Output Voltage Noise Spectrum 5V Start-Up Response with Output Capacitor NOISE VOLTAGE (nV/√Hz) 1000 800 VIN 2V/DIV VIN 2V/DIV VOUT 2V/DIV VOUT 2V/DIV 600 400 200 COUT = 0µF 0 0.01 0.1 1 FREQUENCY (kHz) 100µs/DIV 6652 G33 COUT = 1µF 100µs/DIV 6652 G34 10 6652 G32 6652fe 8 For more information www.linear.com/6652 LTC6652 Typical Performance Characteristics Characteristic curves are similar for most LTC6652s. Curves from the LTC6652-1.25, LTC6652-2.5 and the LTC6652-5 represent the extremes and typical of the voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. Power Supply Rejection Ratio vs Frequency 100 –30 COUT = 1µF –40 –50 –60 COUT = 10µF –70 –80 VTH(UP) 2.0 10 VTRIP (V) –20 2.5 COUT = 0µF COUT = 0µF OUTPUT IMPEDANCE (Ω) POWER SUPPLY REJECTION RATIO (dB) 0 –10 SHDN Input Voltage Thresholds vs VIN Output Impedance vs Frequency COUT = 1µF COUT = 10µF 1 1.5 VTH(DN) 1.0 0.5 –90 –100 0.01 0.1 1 10 FREQUENCY (kHz) 100 1000 0.1 0.01 0.1 1 10 FREQUENCY (kHz) 100 0 2 6 8 VIN (V) 6652 G08 6652 G07 4 10 12 14 6652 G13 Pin Functions DNC (Pin 1): Do Not Connect. GND (Pin 4): Device Ground. VIN (Pin 2): Power Supply. The minimum supply input is VOUT + 300mV or 2.7V; whichever is higher. The maximum supply is 13.2V. Bypassing VIN with a 0.1µF capacitor to GND will improve PSRR. VOUT (Pin 6): Output Voltage. An output capacitor is not required. For some applications, a capacitor between 0.1µF to 10µF can be beneficial. See the graphs in the Typical Performance Characteristics section for further details. SHDN (Pin 3): Shutdown Input. This active low input powers down the device to <2µA. For normal operation tie this pin to VIN. GND (Pins 5,7,8): Internal Function. Ground these pins. 6652fe For more information www.linear.com/6652 9 LTC6652 Block Diagram 2 3 VIN + SHDN VOUT BANDGAP 6 – 4 GND 6652 BD Applications Information Bypass and Load Capacitors The LTC6652 voltage references do not require an input capacitor, but a 0.1µF capacitor located close to the part improves power supply rejection. The LTC6652 voltage references are stable with or without a capacitive load. For applications where an output capacitor is beneficial, a value of 0.1µF to 10µF is recommended depending on load conditions. The Typical Performance Characteristics section includes a plot illustrating a region of marginal stability. Either no or low value capacitors for any load current are acceptable. For loads that sink current or light loads that source current, a 0.1µF to 10µF capacitor has stable operation. For heavier loads that source current a 0.5µF to 10µF capacitor range is recommended. VIN 3V CIN 0.1µF 2, 3 LTC6652-2.5 4, 5, 7, 8 The transient response for a 0.5V step on VIN with and without an output capacitor is shown in Figures 2 and 3, respectively. The LTC6652 references with an output of 2.5V and above are guaranteed to source and sink 5mA. The 1.25V and 2.048V versions are guaranteed to source 5mA and sink 1mA. The test circuit for transient load step response is shown in Figure 1. Figures 4 and 5 show a 5mA source and sink load step response without a load capacitor, respectively. Start-Up The start-up characteristic of the LTC6652 is shown in Figures 8 and 9. Note that the turn-on time is affected by the value of the output capacitor. 6 100Ω COUT 1µF VGEN 0.5V 6652 F01 Figure 1. Transient Load Test Circuit 6652fe 10 For more information www.linear.com/6652 LTC6652 Applications Information VIN 3.5V IOUT 3V VOUT 500mV/DIV 5mA 0mA VOUT 200mV/DIV COUT = 0µF 500µs/DIV COUT = 0µF 6652 F02 Figure 2. Transient Response Without Output Capacitor VIN 250µs/DIV 6652 F05 Figure 5. LTC6652-2.5 Sinking Current Without Output Capacitor 0mA IOUT –5mA 3.5V 3V VOUT 500mV/DIV VOUT 200mV/DIV COUT = 1µF 500µs/DIV 6652 F03 COUT = 1µF 6652 F06 Figure 6. LTC6652-2.5 Sourcing Current with Output Capacitor Figure 3. Transient Response with 1µF Output Capacitor 0mA IOUT –5mA 250µs/DIV IOUT 5mA 0mA VOUT 50mV/DIV VOUT 200mV/DIV COUT = 0µF 250µs/DIV Figure 4. LTC6652-2.5 Sourcing Current Without Output Capacitor 6652 F04 COUT = 1µF 250µs/DIV 6652 F07 Figure 7. LTC6652-2.5 Sinking Current with Output Capacitor 6652fe For more information www.linear.com/6652 11 LTC6652 Applications Information 2.8V ≤ VIN ≤ 13.2V VIN 2V/DIV C1 1µF R1 20k VIN LTC6652-2.5 SHDN TO µC VOUT 1V/DIV COUT = 0µF 100µs/DIV VOUT VOUT GND 2N7002 6652 F10 C2 1µF Figure 10. Open-Drain Shutdown Circuit 6652 F08 Figure 8. Start-Up Response without Output Capacitor SHDN 1V/DIV VIN 2V/DIV VOUT 1V/DIV VOUT 1V/DIV ILOAD = 5mA COUT = 1µF 100µs/DIV 6652 F09 1ms/DIV 6652 F11 Figure 11. Shutdown Response with 5mA Load Figure 9. Start-Up Response with 1µF Output Capacitor In Figure 8, ripple momentarily appears just after the leading edge of powering on. This brief one time event is caused by calibration circuitry during initialization. When an output capacitor is used, the ripple is virtually undetectable as shown in Figure 9. Shutdown Mode Shutdown mode is enabled by tying SHDN low which places the part in a low power state (i.e., <2µA). In shutdown mode, the output pin takes the value 20k • (rated output voltage). For example, an LTC6652-2.5 will have an output impedance of 20k • 2.5 = 50kΩ. For normal operation, SHDN should be greater than or equal to 2.0V. For use with a microcontroller, use a pull-up resistor to VIN and an open-drain output driver as shown in Figure 10. The LTC6652’s response into and out of shutdown mode is shown in Figure 11. The trip thresholds on SHDN have some dependence on the voltage applied to VIN as shown in the Typical Performance Characteristics section. Be careful to avoid leaving SHDN at a voltage between the thresholds as this will likely cause an increase in supply current due to shoot-through current. 6652fe 12 For more information www.linear.com/6652 LTC6652 Applications Information 80 80 40 40 LTC6652-2.5 LS8 PACKAGE 4 TYPICAL PARTS 60 TA = 30°C ppm ppm LTC6652-2.5 MS8 PACKAGE 3 TYPICAL PARTS 60 TA = 35°C 20 20 0 0 –20 –20 –40 0 300 900 600 HOURS 1200 –40 1500 6652 F12a Figure 12a. MS8 Long-Term Drift 35 9 8 30 600 400 HOURS 800 1000 6652 F12b 25°C TO 125°C TO 25°C 25°C TO –40°C TO 25°C 7 25 NUMBER OF UNITS NUMBER OF UNITS 200 Figure 12b. LS8 Long-Term Drift 25°C TO 125°C TO 25°C 25°C TO –40°C TO 25°C 20 15 10 6 5 4 3 2 5 0 –250 0 1 50 –150 –50 DISTRIBUTION (ppm) 0 –110 –80 –50 –20 0 20 50 DISTRIBUTION (ppm) 150 80 110 6652 F13b 6652 F13a Figure 13a. MS8 Hysteresis Plot –40°C to 125°C Figure 13b. LS8 Hysteresis Plot –40°C to 125°C Long-Term Drift Hysteresis Long-term drift cannot be extrapolated from accelerated high temperature testing. This erroneous technique gives drift numbers that are wildly optimistic. The only way long-term drift can be determined is to measure it over the time interval of interest. The LTC6652 long-term drift data was collected on more than 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 = 35°C, their outputs were scanned regularly and measured with an 8.5 digit DVM. Long-term drift is shown below in Figure 12. The hysteresis data shown in Figure 13 represents the worst-case data collected on parts from –40°C to 125°C. The output is capable of dissipating relatively high power, i.e., for the LTC6652-2.5, PD = 10.7V • 5.5mA = 58.85mW. The thermal resistance of the MS8 package is 200°C/W and this dissipation causes a 11.8°C internal rise. This could increase the junction temperature above 125°C and may cause the output to shift due to thermal hysteresis. 6652fe For more information www.linear.com/6652 13 LTC6652 Applications Information PC Board Layout The mechanical stress of soldering a surface mount voltage reference to a PC board can cause the output voltage to shift and temperature coefficient to change. These two changes are not correlated. For example, the voltage may shift, but the temperature coefficient may not. To reduce the effects of stress-related shifts, mount the reference near the short edge of the PC board or in a corner. In addition, slots can be cut into the board on two sides of the device. The capacitors should be mounted close to the package. The GND and VOUT traces should be as short as possible to minimize I • R drops. Excessive trace resistance directly impacts load regulation. IR Reflow Shift The different expansion and contraction rates of the materials that make up the lead-free LTC6652 package cause the output voltage to shift after undergoing IR reflow. Lead-free reflow profiles reach over 250°C, considerably more than their leaded counterparts. The lead-free IR reflow profile used to experimentally measure output voltage shift in the LTC6652-2.5 is shown in Figure 14. Similar results can be 300 380s TP = 260°C TL = 217°C TS(MAX) = 200°C 225 TS = 190°C RAMP DOWN tL 130s RAMP TO 150°C 75 40s 120s 0 0 2 4 6 MINUTES 8 Power Dissipation Power dissipation in the LTC6652 is dependent on VIN, load current, and package. The LTC6652 package has a thermal resistance, or θJA, of 200°C/W. A curve that illustrates allowed power dissipation vs temperature for this package is shown in Figure 16. The power dissipation of the LTC6652-2.5V as a function of input voltage is shown in Figure 17. The top curve shows power dissipation with a 5mA load and the bottom curve shows power dissipation with no load. When operated within its specified limits of VIN = 13.2V and sourcing 5mA, the LTC6652-2.5 consumes just under 60mW at room temperature. At 125°C the quiescent cur rent will be slightly higher and the power consumption increases to just over 60mW. The power-derating curve in Figure 16 shows the LTC6652-2.5 can safely dissipate 125mW at 125°C about half the maximum power con sumption of the package. Humidity Sensitivity tP 30s T = 150°C 150 expected using a convection reflow oven. In our experiment, the serialized parts were run through the reflow process twice. The results indicate that the standard deviation of the output voltage increases with a slight positive mean shift of 0.003% as shown in Figure 15. While there can be up to 0.016% of output voltage shift, the overall drift of the LTC6652 after IR reflow does not vary significantly. 10 6652 F14 Plastic mould compounds absorb water. With changes in relative humidity, plastic packaging materials change the amount of pressure they apply to the die inside, which can cause slight changes in the output of a voltage reference, usually on the order of 100ppm. The LS8 package is hermetic, so it is not affected by humidity, and is therefore more stable in environments where humidity may be a concern. Figure 14. Lead-Free Reflow Profile 6652fe 14 For more information www.linear.com/6652 LTC6652 Applications Information 10 7 NUMBER OF UNITS NUMBER OF UNITS 8 6 4 2 0 1X 3X 6 5 4 3 2 1 0 0.06 –0.1 –0.06 –0.02 0 0.02 0.1 OUTPUT VOLTAGE SHIFT DUE TO IR REFLOW (%) 0.002 0.010 0.018 –0.014 –0.006 OUTPUT VOLTAGE SHIFT DUE TO IR REFLOW (%) 6652 F15b 6652 F15a Figure 15b. LS8 Output Voltage Shift Due to IR Reflow 0.7 0.06 0.6 0.05 0.5 TA = 25°C 0.04 POWER (W) DISSIPATION (W) Figure 15a. MS8 Output Voltage Shift Due to IR Reflow 0.4 0.3 5mA LOAD 0.03 0.02 0.2 0.1 0.01 0 0 0 20 40 60 80 100 TEMPERATURE (°C) 120 140 6652 F16 Figure 16. Maximum Recommended Dissipation for LTC6652 NO LOAD 2 4 6 8 VIN (V) 10 12 14 6652 F17 Figure 17. Typical Power Dissipation of the LTC6652 6652fe For more information www.linear.com/6652 15 LTC6652 Typical Applications Extended Supply Range Reference Extended Supply Range Reference 4V TO 30V R1 330k R1 VIN BZX84C18 LTC6652-2.5 VOUT SHDN C1 0.1µF 6V TO 160V R2 4.7k ON SEMI MMBT5551 VOUT VIN GND C2 OPTIONAL 6652 TA02 GND 6652 TA03 VCC ≥ 1.75V V+ ≥ (VOUT + 1.8V) C1 1µF 2, 3 R1 220Ω VIN LTC6652-2.5 2N2905 SHDN LTC6652-2.5 VOUT 500Ω VEE ≤ –3V C2 OPTIONAL Boosted Output Current Negative Rail Circuit 4, 5, 7, 8 VOUT LTC6652-2.5 VOUT BZX84C18 C1 0.1µF C1 0.1µF 6 SHDN VOUT –2.5V 1µF VOUT C2 1µF GND 6652 TA04 6652 TA06 6652fe 16 For more information www.linear.com/6652 LTC6652 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660 Rev F) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.889 ± 0.127 (.035 ± .005) 5.23 (.206) MIN 0.254 (.010) 7 6 5 0.52 (.0205) REF 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0° – 6° TYP GAUGE PLANE 3.20 – 3.45 (.126 – .136) 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 0.42 ± 0.038 (.0165 ± .0015) TYP 8 0.65 (.0256) BSC RECOMMENDED SOLDER PAD LAYOUT 1 1.10 (.043) MAX 2 3 4 0.86 (.034) REF 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 0.22 – 0.38 (.009 – .015) TYP 0.65 (.0256) BSC 0.1016 ± 0.0508 (.004 ± .002) MSOP (MS8) 0307 REV F 6652fe For more information www.linear.com/6652 17 LTC6652 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. LS8Package Package LS8 8-Leadless 8-Pin LeadlessChip ChipCarrier Carrier(5mm (5mm× ×5mm) 5mm) (ReferenceLTC LTCDWG DWG##05-08-1852 05-08-1852 Rev Ø) (Reference 8 2.50 ±0.15 PACKAGE OUTLINE 7 1 6 2 2.54 ±0.15 5 3 1.50 ±0.15 4 0.70 ±0.05 5.00 SQ ±0.15 5.80 SQ ±0.15 APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 5.00 SQ ±0.15 1.45 ±0.10 0.95 ±0.10 4.20 SQ ±0.10 8 1 PIN 1 TOP MARK (SEE NOTE 5) R0.20 REF 8 2.00 REF 7 2 6 3 5 1 7 4.20 ±0.10 R0.20 REF 6 2 2.54 ±0.15 5 3 1.00 TYP 4 LS8 0609 REV Ø 4 0.70 TYP NOTE: 1. ALL DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS PACKAGE DO NOT INCLUDE PLATING BURRS PLATING BURRS, IF PRESENT, SHALL NOT EXCEED 0.30mm ON ANY SIDE 4. PLATING—ELECTO NICKEL MIN 1.25UM, ELECTRO GOLD MIN 0.30UM 5. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 0.10 TYP 0.64 TYP 6652fe 18 For more information www.linear.com/6652 LTC6652 Revision History (Revision history begins at Rev C) REV DATE DESCRIPTION C 11/09 Change to Typical Performance Characteristics. PAGE NUMBER D 8/12 Change to Typical Application. Addition of 5mm × 5mm Hermetic LS8 Package. Update to Electrical Characteristics to Include LS8 Package. Addition of Long Term Drift, Hysteresis, IR Drift Plots for LS8 Package. E 1/13 6 14 1, 2, 3, 12, 18 4 13, 15 Addition of Humidity Sensitivity Information. 14 Correction to pin labeling of LS8 Package 2 6652fe 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 representaForofmore information www.linear.com/6652 tion that the interconnection its circuits as described herein will not infringe on existing patent rights. 19 LTC6652 Typical Application Improved Reference Supply Rejection in a Data Converter Application LTC1657 DATA VCC 16 D/A GND VDAC REF VIN R1 50k VOUT LTC6652 REF SHDN C1 0.1µF C2 10µF GND COUT 1µF V1 V2 V3 V4 LTC1605 A/D 16 DOUT GND 6652 TA05 Related Parts PART NUMBER DESCRIPTION COMMENTS LT1460 Micropower Series References 0.075% Max, 10ppm/°C Max, 20mA Output Current LT1461 Micropower Series Low Dropout 0.04% Max, 3ppm/°C Max, 50mA Output Current LT1790 Micropower Precision Series References 0.05% Max, 10ppm/°C Max, 60µA Supply, SOT23 Package LT6650 Micropower Reference with Buffer Amplifier 0.5% Max, 5.6µA Supply, SOT23 Package LT6660 Tiny Micropower Series Reference 0.2% Max, 20ppm/°C Max, 20mA Output Current, 2mm × 2mm DFN LT6654 Precision Wide Supply High Output Drive Low Noise Reference 0.05% Max, 10ppm/°C Max, 10mA Output Current, 1.6ppmP-P Noise in SOT23 and LS8 Packages 6652fe 20 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/6652 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/6652 LT 0113 REV E • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2007