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LT1236 Precision Reference
FEATURES
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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(R)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
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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
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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 .................................. 0C to 70C LT1236AI, BI, CI ................................ - 40C to 85C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................ 300C 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 = 125C, JA = 130C/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 = 25C, 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
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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 = 125C, JA = 190C/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 = 25C, 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 VP-P VRMS 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 = 25C
3.0 2.2 20 10
VIN = 15V, IOUT = 0, TA= 25C, 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 VP-P VRMS 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 = 25C
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 25C. 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 = 25C, unless otherwise noted.
temperature. Output voltage is always measured at 25C, but the IC is cycled to 50C or 0C 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, 125C 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 (s)
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 (s)
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 (V)
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 TJ = - 55C 1.0 0.8 0.6 0.4 0.2 0 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 40 TJ = 25C TJ = 125C
40 30 20 10 0 0 2 4 6 8 10 12 14 OUTPUT VOLTAGE (V) 16 18
OUTPUT CHANGE (mV)
Load Transient Response, LT1236-5, CLOAD = 0
ISOURCE = 0 ISINK = 0
OUTPUT VOLTAGE NOISE (5V/DIV)
OUTPUT CHANGE (50mV/DIV)
OUTPUT CHANGE (20mV/DIV)
50mV
50mV
ISOURCE = 0.5mA ISOURCE = 2-10mA
ISINK = 0.2mA ISINK = 2-10mA
ISOURCE = 100AP-P 0 1 2
ISINK = 100AP-P 1 2 3 4
340 TIME (s)
UW
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
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 5V (1ppm)
20mV
20mV
ISOURCE = 0.2mA
ISINK = 0.2mA ISINK = 2-10mA
ISOURCE = 2-10mA ISOURCE = 100AP-P 0 5 ISINK = 100AP-P 5 10 15 20
LT1236 G14
10 15 20 0 TIME (s)
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 = 125C TJ = 25C TJ = - 55C
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 (10V/DIV)
10mV ISINK = 0.8mA ISOURCE = 0.2mA
ISINK = 1.0mA ISINK = 2-10mA ISINK = 100AP-P 1 2 3 4
ISOURCE = 2-10mA ISOURCE = 100AP-P 0 1 2
340 TIME (s)
NOTE VERTICAL SCALE CHANGE BETWEEN SOURCING AND SINKING
LT1236 G22
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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 = - 55C TJ = 25C TJ = 125C
-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 10V (1ppm)
ISOURCE = 0.5mA
ISINK = 1.4mA
ISOURCE = 2-10mA ISOURCE = 100AP-P 0 1 2
ISINK = 2-10mA ISINK = 100AP-P 1 2 3 4
340 TIME (s)
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 25C to 65C. Assuming the system calibration is performed at 25C, the temperature span is 40C. 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 12k with a nominal open circuit voltage of 5V. It is designed to be driven from a source impedance of 3k 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 10k 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
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in series with a 20k 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 100k 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 10F 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
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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 220 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 220 2N2905
IN LT1236 OUT GND 10V AT 100mA
+
2F SOLID TANT
LT1236 TA05
Handling Higher Load Currents
15V 30mA
IN LT1236-10 OUT GND
R1* 169 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 40.2 1% 1.2k -15V *TC LESS THAN 200ppm/C **NO ZERO ADJUST REQUIRED WITH LT1007 (V0S 60V) CMOS DAC LTC7543 FB 30pF IOUT
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Boosted Output Current with Current Limit
V+ VOUT + 2.8V D1* LED R1 220 8.2
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
+
2F 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* 5F
1N914
+ C2*
5F
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* 100 FULL-SCALE ADJUST 10V F.S.
-
LT1007C
4.32k 5k V - = -15V* *MUST BE WELL REGULATED dVOUT 15mV = V dV -
+
LT1236 TA14
LT1236 TA11
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LT1236 TYPICAL APPLICATIONS
Strain Gauge Conditioner for 350 Bridge
R1 357 1/2W
28mA LT1236-10 15V IN GND OUT 28.5mA 5V 350 STRAIN GAUGE BRIDGE** R2 20k R4 20k R3 2M
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 1M. 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
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Negative Shunt Reference Driven by Current Source
LT1236-10 OUT GND -10V (ILOAD 1mA) 2.5mA
2
-
+
-
LT1012C 6 VOUT X100
LM334
3 R5 2M
+
27
R6* 2M
-5V 357 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
1F MYLAR
VIN
-
LT1236 VIN
10k 1% 50k ROOM TEMP TRIM
LT1001
VREF
IN GND
OUT R1 36k f = 10Hz R2 36k
+
0.5F MYLAR TOTAL NOISE 2VRMS 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 R10 182k 1% R14 5k IN 20V
R9 100k
R8 10M
R3** 5k RS 100 AT 0C 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 VOUT =100mV/C -50C T 150C
3
4 -15V
R6 619k 1%
STANDARD INDUSTRIAL 100 PLATINUM 4-WIRE SENSOR, ROSEMOUNT 78S OR EQUIVALENT. = 0.00385 TRIM R9 FOR VOUT = 0V AT 0C TRIM R12 FOR VOUT = 10V AT 100C TRIM R14 FOR VOUT = 5V AT 50C USE TRIM SEQUENCE AS SHOWN. TRIMS ARE NONINTERACTIVE SO THAT ONLY ONE TRIM SEQUENCE IS NORMALLY REQUIRED. *FEEDBACK LINEARIZES OUTPUT TO 0.005C FROM - 50C TO 150C 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 x 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
(c) LINEAR TECHNOLOGY CORPORATION 1995

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