LT1236-5

LT1236 Precision Reference FEATURES s s s s s s s s s s DESCRIPTIO Ultra-Low Drift: 5ppm/°C Max Trimmed to High Accuracy: 0.05% Max Industrial Temperature Range SO Package Operates in Series or Shunt Mode Pin Compatible with AD586, AD587 Output Sinks and Sources in Series Mode Very Low Noise < 1ppm P-P (0.1Hz to 10Hz) 100% Noise Tested > 100dB Ripple Rejection Minimum Input/Output Differential of 1V The LT®1236 is a precision reference that combines ultralow drift and noise with excellent long-term stability and high output accuracy. The reference output will both source and sink up to 10mA and is almost totally immune to input voltage variations. Two voltages are available: 5V and 10V. The 10V version can be used as a shunt regulator (two-terminal zener) with the same precision characteristics as the three-terminal connection. Special care has been taken to minimize thermal regulation effects and temperature induced hysteresis. The LT1236 combines both superior accuracy and temperature coefficient specifications without the use of high power, on-chip heaters. The LT1236 references are based on a buried zener diode structure which eliminates noise and stability problems with surface breakdown devices. Further, a subsurface zener exhibits better temperature drift and time stability than even the best band-gap references. , LTC and LT are registered trademarks of Linear Technology Corporation. APPLICATI s s s s s S A/D and D/A Converters Precision Regulators Precision Scales Inertial Navigation Systems Digital Voltmeters TYPICAL APPLICATI Basic Positive and Negative Connections Typical Distribution of Temperature Drift DISTRIBUTION 22 OF THREE RUNS 20 18 16 UNITS (%) 24 LT1236 VIN IN GND OUT VOUT NC LT1236-10 IN GND –VOUT V – (V – ) R1 = OUT ILOAD + 1.5mA R1 –15V (V – ) LT1236 TA01 OUT 14 12 10 8 6 4 2 0 –3 –2 –1 0 1 OUTPUT DRIFT (ppm/°C) 2 3 U LT1236 TA02 UO UO 1 LT1236 ABSOLUTE AXI U RATI GS Output Short-Circuit Duration VIN = 35V ......................................................... 10 sec VIN ≤ 20V ................................................... Indefinite Operating Temperature Range LT1236AC, BC, CC .................................. 0°C to 70°C LT1236AI, BI, CI ................................ – 40°C to 85°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................ 300°C Input Voltage .......................................................... 40V Input/Output Voltage Differential ............................ 35V Output-to-Ground Voltage (Shunt Mode Current Limit) LT1236-5 ............................................................. 10V LT1236-10 ........................................................... 16V Trim Pin-to-Ground Voltage Positive................................................ Equal to VOUT Negative ........................................................... – 20V PACKAGE/ORDER I FOR ATIO ORDER PART NUMBER TOP VIEW NC* 1 VIN 2 NC* 3 GND 4 N8 PACKAGE 8-LEAD PDIP *CONNECTED INTERNALLY. D0 NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS **SEE APPLICATIONS INFORMATION SECTION 8 7 6 5 NC* NC* V0UT TRIM** TJMAX = 125°C, θJA = 130°C/W LT1236ACN8-5 LT1236BCN8-5 LT1236CCN8-5 LT1236ACN8-10 LT1236BCN8-10 LT1236CCN8-10 LT1236AIN8-5 LT1236BIN8-5 LT1236CIN8-5 LT1236AIN8-10 LT1236BIN8-10 LT1236CIN8-10 Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS PARAMETER Output Voltage (Note 1) Output Voltage Temperature Coefficient (Note 2) CONDITIONS VIN = 10V, IOUT = 0, TA = 25°C, unless otherwise noted. MIN 4.9975 4.9950 LT1236-5 TYP 5.000 5.000 2 5 10 4 q LT1236A-5 LT1236B-5/LT1236C-5 TMIN ≤ TJ ≤ TMAX LT1236A-5 LT1236B-5 LT1236C-5 7.2V ≤ VIN ≤ 10V 10V ≤ VIN ≤ 40V q Line Regulation (Note 3) Load Regulation (Sourcing Current) (Note 3) 0 ≤ IOUT ≤ 10mA q 2 U U W WW U W ORDER PART NUMBER TOP VIEW NC* 1 VIN 2 NC* 3 GND 4 8 7 6 5 NC* NC* V0UT TRIM** S8 PACKAGE 8-LEAD PLASTIC SO *CONNECTED INTERNALLY. D0 NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS **SEE APPLICATIONS INFORMATION SECTION LT1236ACS8-5 LT1236BCS8-5 LT1236CCS8-5 LT1236ACS8-10 LT1236BCS8-10 LT1236CCS8-10 LT1236AIS8-5 LT1236BIS8-5 LT1236CIS8-5 LT1236AIS8-10 LT1236BIS8-10 LT1236CIS8-10 S8 PART MARKING 236AC5 236BC5 236CC5 236AC1 236BC1 236CC1 236AI5 236BI5 236CI5 236AI1 236BI1 236CI1 TJMAX = 125°C, θJA = 190°C/W MAX 5.0025 5.0050 5 10 15 12 20 6 10 20 35 UNITS V V ppm/°C ppm/°C ppm/°C ppm/V ppm/V ppm/V ppm/V ppm/mA ppm/mA 2 10 LT1236 ELECTRICAL CHARACTERISTICS PARAMETER Load Regulation (Sinking Current) (Note 3) Supply Current CONDITIONS VIN = 10V, IOUT = 0, TA = 25°C, unless otherwise noted. MIN q LT1236-5 TYP 60 0.8 MAX 100 150 1.2 1.5 3.5 UNITS ppm/mA ppm/mA mA mA µVP-P µVRMS ppm ppm 0 ≤ IOUT ≤ 10mA q Output Voltage Noise (Note 5) Long-Term Stability of Output Voltage (Note 6) Temperature Hysteresis of Output (Note 7) 0.1Hz ≤ f ≤ 10Hz 10Hz ≤ f ≤ 1kHz ∆t = 1000Hrs Non-Cumulative ∆T = ±25°C 3.0 2.2 20 10 VIN = 15V, IOUT = 0, TA= 25°C, unless otherwise noted. PARAMETER Output Voltage (Note 1) Output Voltage Temperature Coefficient (Note 2) CONDITIONS LT1236A-10 LT1236B-10/LT1236C-10 TMIN ≤ TJ ≤ TMAX LT1236A-10 LT1236B-10 LT1236C-10 11.5V ≤ VIN ≤ 14.5V q MIN 9.995 9.990 LT1236-10 TYP 10.000 10.000 2 5 10 1.0 0.5 MAX 10.005 10.010 5 10 15 4 6 2 4 25 40 100 150 1.7 2.0 1.5 1.7 6 UNITS V V ppm/°C ppm/°C ppm/°C ppm/V ppm/V ppm/V ppm/V ppm/mA ppm/mA ppm/mA ppm/mA mA mA mA mA µVP-P µVRMS ppm ppm Line Regulation (Note 3) 14.5V ≤ VIN ≤ 40V q Load Regulation (Sourcing Current) (Note 3) Load Regulation (Shunt Mode) (Notes 3, 4) Series Mode Supply Current 0 ≤ IOUT ≤ 10mA q 12 50 q 1.7mA ≤ ISHUNT ≤ 10mA 1.2 q Shunt Mode Minimum Current Output Voltage Noise (Note 5) Long-Term Stablility of Output Voltage (Note 6) Temperature Hysteresis of Output (Note 7) VIN is Open q 1.1 6.0 3.5 30 5 0.1Hz ≤ f ≤ 10Hz 10Hz ≤ f ≤ 1kHz ∆t = 1000Hrs Non-Cumulative ∆T = ±25°C The q denotes specifications which apply over the specified temperature range. Note 1: Output voltage is measured immediately after turn-on. Changes due to chip warm-up are typically less than 0.005%. Note 2: Temperature coefficient is measured by dividing the change in output voltage over the temperature range by the change in temperature. Incremental slope is also measured at 25°C. Note 3: Line and load regulation are measured on a pulse basis. Output changes due to die temperature change must be taken into account separately. Note 4: Shunt mode regulation is measured with the input open. With the input connected, shunt mode current can be reduced to 0mA. Load regulation will remain the same. Note 5: RMS noise is measured with a 2-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. Correction factors are used to convert from average to RMS, and 0.88 is used to correct for the non-ideal bandbass of the filters. Peak-to-peak noise is measured with a single highpass filter at 0.1Hz and a 2-pole lowpass filter at 10Hz. The unit is enclosed in a still-air environment to eliminate thermocouple effects on the leads. Test time is 10 seconds. Note 6: 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. Significant improvement in long-term drift can be 3 LT1236 ELECTRICAL CHARACTERISTICS VIN = 15V, IOUT = 0, TA = 25°C, unless otherwise noted. temperature. Output voltage is always measured at 25°C, but the IC is cycled to 50°C or 0°C before successive measurements. Hysteresis is roughly proportional to the square of temperature change. Hysteresis is not normally a problem for operational temperature excursions, but can be significant in critical narrow temperature range applications where the instrument might be stored at high or low temperatures. realized by preconditioning the IC with a 100-200 hour, 125°C burn in. Long term stability will also be affected by differential stresses between the IC and the board material created during board assembly. Temperature cycling and baking of completed boards is often used to reduce these stresses in critical applications. Note 7: Hysteresis in output voltage is created by package stress that differs depending on whether the IC was previously at a higher or lower TYPICAL PERFOR A CE CHARACTERISTICS Ripple Rejection 115 f = 150Hz 110 REJECTION (dB) REJECTION (dB) INPUT/OUTPUT VOLTAGE (V) 105 100 LT1236-10 LT1236-5 95 90 85 0 5 10 15 20 25 30 INPUT VOLTAGE (V) Start-Up (Series Mode) 13 12 11 VIN = 0V TO 12V NOISE VOLTAGE (nV/√Hz) OUTPUT VOLTAGE (V) 10 9 8 7 6 5 4 3 0 2 4 OUTPUT VOLTAGE (V) LT1236-10 LT1236-5 6 8 TIME (µs) 10 4 UW 35 LT1236 G01 Ripple Rejection 130 120 110 100 90 80 70 60 50 40 10 100 1k FREQUENCY (Hz) 10k LT1236 G02 Minimum Input/Output Differential, LT1236-10 1.6 1.4 TJ = 125 °C TJ = – 55 °C TJ = 25 °C VIN = 15V COUT = 0 LT1236-10 1.2 1.0 0.8 0.6 0.4 0.2 0 0 LT1236-5 2 4 6 8 10 12 14 16 18 20 OUTPUT CURRENT (mA) LT1236 G03 Start-Up (Shunt Mode), LT1236-10 11 LT1236-10 10 9 VOUT + 2V 1k VOUT OUT IN GND Output Voltage Noise Spectrum 400 350 300 250 200 150 100 50 0 LT1236-10 LT1236-5 8 7 6 5 0V NC 12 14 0 2 6 4 TIME (µs) 8 10 12 10 1k 100 FREQUENCY (Hz) 1M LT1236 G06 LT1236 G04 LT1236 G05 LT1236 TYPICAL PERFOR A CE CHARACTERISTICS Output Voltage Noise 16 14 12 COUT = 0 FILTER = 1 POLE fLOW = 0.1Hz OUTPUT VOLTAGE (V) 5.005 OUTPUT CHANGE (mV) RMS NOISE (µV) 10 8 6 4 2 LT1236-5 0 10 100 1k BANDWIDTH (Hz) 10k LT1236 G07 LT1236-10 Quiescent Current, LT1236-5 1.8 1.6 1.4 CURRENT INTO OUTPUT (mA) IOUT = 0 INPUT CURRENT (mA) 1.2 1.0 0.8 0.6 0.4 0.2 0 0 5 10 TJ = – 55°C TJ = 25°C TJ = 125°C 40 30 20 10 0 OUTPUT CHANGE (mV) 15 20 25 30 INPUT VOLTAGE (V) Load Transient Response, LT1236-5, CLOAD = 0 ISOURCE = 0 ISINK = 0 OUTPUT VOLTAGE NOISE (5µV/DIV) OUTPUT CHANGE (50mV/DIV) OUTPUT CHANGE (20mV/DIV) 50mV 50mV ISOURCE = 0.5mA ISOURCE = 2-10mA ISINK = 0.2mA ISINK = 2-10mA ∆ISOURCE = 100µAP-P 0 1 2 ∆ISINK = 100µAP-P 1 2 3 4 340 TIME (µs) UW 35 40 LT1236 G10 Output Voltage Temperature Drift LT1236-5 5 4 5.004 Load Regulation LT1236-5 VIN = 8V 3 2 1 0 –1 –2 –3 –4 5.003 5.002 5.001 5.000 –40 –20 40 20 0 60 TEMPERATURE (°C) 80 100 –5 –10 – 8 – 6 – 4 – 2 SOURCING 0 2 468 SINKING 10 LT1236 G08 OUTPUT CURRENT (mA) LT1236 G09 Sink Mode* Current Limit, LT1236-5 60 50 0 – 0.5 – 1.0 Thermal Regulation, LT1236-5 VIN = 25V ∆POWER = 200mW LOAD REGULATION THERMAL REGULATION* VIN = 8V ILOAD = 10mA 0 2 4 6 8 10 12 14 OUTPUT VOLTAGE (V) 16 18 0 20 40 60 80 TIME (ms) 100 120 140 *NOTE THAT AN INPUT VOLTAGE IS REQUIRED FOR 5V UNITS. LT1236 G11 *INDEPENDENT OF TEMPERATURE COEFFICIENT LT1236 G12 Load Transient Response, LT1236-5, CLOAD = 1000pF ISOURCE = 0 ISINK = 0 Output Noise 0.1Hz to 10Hz, LT1236-5 FILTERING = 1 ZERO AT 0.1Hz 2 POLES AT 10Hz 5µV (1ppm) 20mV 20mV ISOURCE = 0.2mA ISINK = 0.2mA ISINK = 2-10mA ISOURCE = 2-10mA ∆ISOURCE = 100µAP-P 0 5 ∆ISINK = 100µAP-P 5 10 15 20 LT1236 G14 10 15 20 0 TIME (µs) 0 1 4 3 2 TIME (MINUTES) 5 6 LT1236 G13 LT1236 G15 5 LT1236 TYPICAL PERFOR A CE CHARACTERISTICS Output Voltage Temperature Drift, LT1236-10 10.0020 10.0015 5 4 3 OUTPUT CHANGE (mV) OUTPUT VOLTAGE (V) 2 1 0 –1 –2 –3 INPUT CURRENT (mA) 10.0010 10.0005 10.0000 9.9995 9.9990 9.9985 9.9980 –40 –20 0 20 60 40 TEMPERATURE (˚C) 80 100 Shunt Characteristics, LT1236-10 1.8 1.6 CURRENT INTO OUTPUT (mA) CURRENT INTO OUTPUT (mA) INPUT PIN OPEN 1.2 1.0 0.8 0.6 0.4 0.2 0 0 2 4 6 10 8 OUTPUT TO GROUND VOLTAGE (V) 12 TJ = 25°C TJ = 125°C TJ = – 55°C 40 30 20 10 0 0 2 4 6 8 10 12 14 OUTPUT VOLTAGE (V) 16 18 OUTPUT CHANGE (mV) 1.4 Load Transient Response, LT1236-10, CLOAD = 0 ISINK = 0.6mA ISOURCE = 0 OUTPUT VOLTAGE CHANGE OUTPUT VOLTAGE CHANGE ISOURCE = 0 50mV 20mV 5mV ISINK = 1.2mA OUTPUT VOLTAGE NOISE (10µV/DIV) 10mV ISINK = 0.8mA ISOURCE = 0.2mA ISINK = 1.0mA ISINK = 2-10mA ∆ISINK = 100µAP-P 1 2 3 4 ISOURCE = 2-10mA ∆ISOURCE = 100µAP-P 0 1 2 340 TIME (µs) NOTE VERTICAL SCALE CHANGE BETWEEN SOURCING AND SINKING LT1236 G22 6 UW LT1236 G19 Load Regulation, LT1236-10 VIN = 12V Input Supply Current, LT1236-10 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 IOUT = 0 TJ = – 55°C TJ = 25°C TJ = 125°C –4 –5 –10 – 8 – 6 – 4 – 2 SOURCING 0 2 468 SINKING 10 0 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 40 LT1236 G16 OUTPUT CURRENT (mA) LT1236 G17 LT1236 G18 Shunt Mode Current Limit, LT1236-10 60 50 0 – 0.5 –1.0 –1.5 Thermal Regulation, LT1236-10 VIN = 30V ∆POWER = 200mW LOAD REGULATION INPUT PIN OPEN THERMAL REGULATION* ILOAD = 10mA 0 20 40 60 80 TIME (ms) 100 120 140 LT1236 G20 *INDEPENDENT OF TEMPERATURE COEFFICIENT LT1236 G21 Load Transient Response, LT1236-10, CLOAD = 1000pF ISINK = 0.8mA Output Noise 0.1Hz to 10Hz, LT1236-10 FILTERING = 1 ZERO AT 0.1Hz 2 POLES AT 10Hz 10µV (1ppm) ISOURCE = 0.5mA ISINK = 1.4mA ISOURCE = 2-10mA ∆ISOURCE = 100µAP-P 0 1 2 ISINK = 2-10mA ∆ISINK = 100µAP-P 1 2 3 4 340 TIME (µs) 0 1 4 3 2 TIME (MINUTES) 5 6 NOTE VERTICAL SCALE CHANGE BETWEEN SOURCING AND SINKING LT1236 G23 LT1236 G24 LT1236 APPLICATIONS INFORMATION Effect of Reference Drift on System Accuracy A large portion of the temperature drift error budget in many systems is the system reference voltage. This graph indicates the maximum temperature coefficient allowable if the reference is to contribute no more than 0.5LSB error to the overall system performance. The example shown is a 12-bit system designed to operate over a temperature range from 25°C to 65°C. Assuming the system calibration is performed at 25°C, the temperature span is 40°C. It can be seen from the graph that the temperature coefficient of the reference must be no worse than 3ppm/°C if it is to contribute less than 0.5LBS error. For this reason, the LT1236 family has been optimized for low drift. Maximum Allowable Reference Drift MAXIMUM TEMPERATURE COEFFICIENT FOR 0.5LSB ERROR (ppm/°C) 100 8-BIT 10-BIT 10 12-BIT 14-BIT 1.0 10 20 30 40 50 60 70 80 90 100 TEMPERATURE SPAN (°C) LT1236 AI01 Trimming Output Voltage The LT1236-10 has a trim pin for adjusting output voltage. The impedance of the trim pin is about 12kΩ with a nominal open circuit voltage of 5V. It is designed to be driven from a source impedance of 3kΩ or less to minimize changes in the LT1236 TC with output trimming. Attenuation between the trim pin and the output is 70:1. This allows ± 70mV trim range when the trim pin is tied to the wiper of a potentiometer connected between the output and ground. A 10kΩ potentiometer is recommended, preferably a 20 turn cermet type with stable characteristics over time and temperature. The LT1236-10 “A” version is pre-trimmed to ± 5mV and therefore can utilize a restricted trim range. A 75k resistor U W U U in series with a 20kΩ potentiometer will give ± 10mV trim range. Effect on the output TC will be only 1ppm/°C for the ± 5mV trim needed to set the “A” device to 10.000V. LT1236-5 The LT1236-5 does have an output voltage trim pin, but the TC of the nominal 4V open circuit voltage at pin 5 is about –1.7mV/°C. For the voltage trimming not to affect reference output TC, the external trim voltage must track the voltage on the trim pin. Input impedance of the trim pin is about 100kΩ and attenuation to the output is 13:1. The technique shown below is suggested for trimming the output of the LT1236-5 while maintaining minimum shift in output temperature coefficient. The R1/R2 ratio is chosen to minimize interaction of trimming and TC shifts, so the exact values shown should be used. LT1236-5 IN GND OUT TRIM R1 27k R2 50k 1N4148 VOUT LT1236 AI02 Capacitive Loading and Transient Response The LT1236 is stable with all capacitive loads, but for optimum settling with load transients, output capacitance should be under 1000pF. The output stage of the reference is class AB with a fairly low idling current. This makes transient response worse-case at light load currents. Because of internal current drain on the output, actual worst-case occurs at ILOAD = 0 on LT1236-5 and ILOAD = 1.4mA (sinking) on LT1236-10. Significantly better load transient response is obtained by moving slightly away from these points. See Load Transient Response curves for details. In general, best transient response is obtained when the output is sourcing current. In critical applications, a 10µF solid tantalum capacitor with several ohms in series provides optimum output bypass. 7 LT1236 APPLICATIONS INFORMATION Kelvin Connections Although the LT1236 does not have true force/sense capability at its outputs, significant improvements in ground loop and line loss problems can be achieved with proper hook-up. In series mode operation, the ground pin of the LT1236 carries only ≈ 1mA and can be used as a sense line, greatly reducing ground loop and loss problems on the low side of the reference. The high side supplies load current so line resistance must be kept low. Twelve feet of #22 gauge hook-up wire or 1 foot of 0.025 inch printed circuit trace will create 2mV loss at 10mA output current. This is equivalent to 1LSB in a 10V, 12-bit system. The following circuits show proper hook-up to minimize errors due to ground loops and line losses. Losses in the output lead can be greatly reduced by adding a PNP boost transistor if load currents are 5mA or higher. R2 can be added to further reduce current in the output sense lead. Effects of Air Movement on Low Frequency Noise The LT1236 has very low noise because of the buried zener used in its design. In the 0.1Hz to 10Hz band, peak-to-peak noise is about 0.5ppm of the DC output. To achieve this low noise, however, care must be taken to shield the reference from ambient air turbulence. Air movement can create noise because of thermoelectric differences between IC package leads and printed circuit board materials and/or sockets. Power dissipation in the reference, even though it rarely exceeds 20mW, is enough to cause small IN LT1236 OUT GND R2* LOAD TYPICAL APPLICATIONS Restricted Trim Range for Improved Resolution, 10V, “A” Version Only LT1236-10 Full Trim Range (±0.7%) Negative Series Reference 15V LT1236-10 LT1236A-10 VIN IN GND OUT TRIM R1 75k 10.000V VIN R2 50k TRIM RANGE ≈ ±10mV LT1236 TA10 *CAN BE RAISED TO 20k FOR LESS CRITICAL APPLICATIONS 8 U W U U U temperature gradients in the package leads. Variations in thermal resistance, caused by uneven air flow, create differential lead temperatures, thereby causing thermoelectric voltage noise at the output of the reference. Standard Series Mode LT1236 INPUT IN GND OUT KEEP THIS LINE RESISTANCE LOW + LOAD GROUND RETURN LT1236 AI03 Series Mode with Boost Transistor INPUT R1 220Ω 2N3906 GROUND RETURN *OPTIONAL—REDUCES CURRENT IN OUTPUT SENSE LEAD: R2 = 2.4k (LT1236-5), 5.6k (LT1236-10) LT1236 AI04 IN GND OUT TRIM VOUT R1 4.7k D1 15V LT1236-10 IN OUT GND R1* 10k R2 4.7k –15V LT1236 TA03 Q1 2N2905 –10V AT 50mA LT1236 TA04 LT1236 TYPICAL APPLICATIONS Boosted Output Current with No Current Limit V + ≥ (VOUT + 1.8V) R1 220Ω 2N2905 IN LT1236 OUT GND 10V AT 100mA + 2µF SOLID TANT LT1236 TA05 Handling Higher Load Currents 15V 30mA IN LT1236-10 OUT GND R1* 169Ω VOUT 10V RL TYPICAL LOAD CURRENT = 30mA *SELECT R1 TO DELIVER TYPICAL LOAD CURRENT. LT1236 WILL THEN SOURCE OR SINK AS NECESSARY TO MAINTAIN PROPER OUTPUT. DO NOT REMOVE LOAD AS OUTPUT WILL BE DRIVEN UNREGULATED HIGH. LINE REGULATION IS DEGRADED IN THIS APPLICATION LT1236 TA07 CMOS DAC with Low Drift Full-Scale Trimming** LT1236-10 OUT LT1236-10 TRIM GND R1 4.99k 1% REF R2 40.2Ω 1% 1.2k –15V *TC LESS THAN 200ppm/°C **NO ZERO ADJUST REQUIRED WITH LT1007 (V0S ≤ 60µV) CMOS DAC LTC7543 FB 30pF IOUT U Boosted Output Current with Current Limit V+ ≥ VOUT + 2.8V D1* LED R1 220Ω 8.2Ω ±10V Output Reference LT1236-10 15V VIN GND COM VOUT +10V 2N2905 IN LT1236 OUT GND 10V AT 100mA LT1236-10 V IN GND –10V VOUT + 2µF SOLID TANT *GLOWS IN CURRENT LIMIT, DO NOT OMIT LT1236 TA06 –15V –10V R1 = ILOAD + 1.5mA R1 ILOAD –15V LT1236 TA17 Operating 5V Reference from 5V Supply 5V LOGIC SUPPLY 1N914 CMOS LOGIC GATE** fIN ≥ 2kHz* LT1236-5 ≈ 8.5V + C1* 5µF 1N914 + C2* 5µF IN GND OUT 5V REFERENCE *FOR HIGHER FREQUENCIES C1 AND C2 MAY BE DECREASED **PARALLEL GATES FOR HIGHER REFERENCE CURRENT LOADING LT1236 TA15 Trimming 10V Units to 10.24V R3 4.02K 1% VIN IN TRIM OUT GND VOUT = 10.24V R4* 100Ω FULL-SCALE ADJUST 10V F.S. – LT1007C 4.32k 5k V – = –15V* *MUST BE WELL REGULATED dVOUT 15mV = V dV – + LT1236 TA14 LT1236 TA11 9 LT1236 TYPICAL APPLICATIONS Strain Gauge Conditioner for 350Ω Bridge R1 357Ω 1/2W 28mA LT1236-10 15V IN GND OUT 28.5mA 5V 350Ω STRAIN GAUGE BRIDGE** R2 20k R4 20k 3 6 1 LM301A† 2 100pF 8 *THIS RESISTOR PROVIDES POSITIVE FEEDBACK TO THE BRIDGE TO ELIMINATE LOADING EFFECT OF THE AMPLIFIER. EFFECTIVE ZIN OF AMPLIFIER STAGE IS ≥ 1MΩ. IF R2 TO R5 ARE CHANGED, SET R6 = R3 Precision DAC Reference with System TC Trim LT1236-10 15V IN GND OUT 8.87k 1% D1 1N457 1.24k 1% 50k TC TRIM* 10k 1% *TRIMS 1mA REFERENCE CURRENT TC BY ±40ppm/°C. THIS TRIM SCHEME HAS VERY LITTLE EFFECT ON ROOM TEMPERATURE CURRENT TO MINIMIZE ITERATIVE TRIMMING 10 U Negative Shunt Reference Driven by Current Source LT1236-10 OUT GND R3 2M –10V (ILOAD ≤ 1mA) 2.5mA 2 – + – LT1012C 6 VOUT X100 LM334 3 R5 2M + 27Ω R6* 2M –5V 357Ω 1/2W –15V **BRIDGE IS ULTRA-LINEAR WHEN ALL LEGS ARE ACTIVE, TWO IN COMPRESSION AND TWO IN TENSION, OR WHEN ONE SIDE IS ACTIVE WITH ONE COMPRESSED AND ONE TENSIONED LEG † OFFSET AND DRIFT OF LM301A ARE VIRTUALLY ELIMINATED BY DIFFERENTIAL CONNECTION OF LT1012C LT1236 TA08 –11V TO – 40V LT1236 TA13 2-Pole Lowpass Filtered Reference 1µF MYLAR VIN – LT1236 VIN 10k 1% 50k ROOM TEMP TRIM LT1001 VREF IN GND OUT R1 36k f = 10Hz R2 36k + 0.5µF MYLAR TOTAL NOISE ≤ 2µVRMS 1Hz ≤ f ≤ 10kHz 10.36k 1% D2 1N457 50k 200k 1% 1mA 8.45k –VREF LT1236 TA12 DAC LT1236 TA16 LT1236 TYPICAL APPLICATIONS Ultra-Linear Platinum Temperature Sensor* LT1236-10 OUT GND R2* 5k R1** 253k R11 6.65M 1% R15 10k R12 1k R13 24.3k 6 VOUT =100mV/°C –50°C ≤ T ≤ 150°C R10 182k 1% R14 5k IN 20V R9 100k R8 10M R3** 5k RS† 100Ω AT 0°C R7 392k 1% –15V EQUIVALE T SCHE ATIC INPUT Q3 D1 D2 OUTPUT D3 Q1 R1 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 Rf** 654k 20V R4 4.75k 1% R5 200k 1% 2 – + 7 LT1001 3 4 –15V R6 619k 1% STANDARD INDUSTRIAL 100Ω PLATINUM 4-WIRE SENSOR, ROSEMOUNT 78S OR EQUIVALENT. α = 0.00385 TRIM R9 FOR VOUT = 0V AT 0°C TRIM R12 FOR VOUT = 10V AT 100°C TRIM R14 FOR VOUT = 5V AT 50°C USE TRIM SEQUENCE AS SHOWN. TRIMS ARE NONINTERACTIVE SO THAT ONLY ONE TRIM SEQUENCE IS NORMALLY REQUIRED. *FEEDBACK LINEARIZES OUTPUT TO ± 0.005°C FROM – 50°C TO 150°C LT1236 TA09 **WIREWOUND RESISTORS WITH LOW TC † W U – A1 D4 6.3V + R2 Q2 GND LT1236 ES 11 LT1236 PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. N8 Package 8-Lead Plastic DIP 0.400* (10.160) MAX 8 7 6 5 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) 0.065 (1.651) TYP 0.125 (3.175) MIN 0.018 ± 0.003 (0.457 ± 0.076) 0.015 (0.380) MIN ( +0.025 0.325 –0.015 +0.635 8.255 –0.381 ) 0.045 ± 0.015 (1.143 ± 0.381) 0.100 ± 0.010 (2.540 ± 0.254) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm). 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0°– 8° TYP 0.053 – 0.069 (1.346 – 1.752) 0.016 – 0.050 0.406 – 1.270 *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm). 1 2 3 4 SO8 0294 RELATED PARTS PART NUMBER LT1019 LT1027 DESCRIPTION Precision Bandgap Reference Precision 5V Reference COMMENTS 0.05%, 5ppm/°C 0.02%, 2ppm/°C 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977 U 0.045 – 0.065 (1.143 – 1.651) 0.130 ± 0.005 (3.302 ± 0.127) 0.255 ± 0.015* (6.477 ± 0.381) 1 2 3 4 N8 0395 S8 Package 8-Lead Plastic SOIC 0.189 – 0.197* (4.801 – 5.004) 0.004 – 0.010 (0.101 – 0.254) 8 7 6 5 0.014 – 0.019 (0.355 – 0.483) 0.050 (1.270) BSC 0.228 – 0.244 (5.791 – 6.197) 0.150 – 0.157* (3.810 – 3.988) LT/GP 0695 10K • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 1995