1
LT1031/LH0070
1031fb
■
Pin Compatible with LH0070 and AD581*
■
Ultralow Drift—5ppm/°C Max Slope
■
Trimmed Output Voltage
■
Operates in Series or Shunt Mode
■
Output Sinks and Sources in Series Mode
■
Very Low Noise < 1ppm
P-P
0.1Hz to 10Hz
■
> 100dB Ripple Rejection
■
Minimum Input Voltage of 11V
The LT
®
1031 is a precision 10V reference with ultralow
drift and noise, extremely good long term stability, and
almost total immunity to input voltage variations. The
reference output will both source and sink up to 10mA and
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 LT1031 reference is based on a buried Zener diode
structure which eliminates noise and stability problems
associated with surface breakdown devices. Further, a
subsurface Zener exhibits better temperature drift and
time stability than even the best band-gap references.
Unique circuit design makes the LT1031 the first three
terminal IC reference to offer ultralow drift without the
use of high power on-chip heaters. Output voltage is
pretrimmed to 0.05% accuracy.
The LT1031 can be used as a plug-in replacement for
the AD581 and LH0070,* with improved electrical and
thermal performance.
■
A-to-D and D-to-A Converters
■
Precision Regulators
■
Digital Voltmeters
■
lnertial Navigation Systems
■
Precision Scales
■
Portable Reference Standard
Basic Positive and
Negative Connections
Precision 10V Reference
Distribution of Output Accuracy
FEATURES
APPLICATIO S
U
DESCRIPTIO
U
V
OUT
I
LOAD
+ 1.5mA
–V
OUT
–V
IN
V
IN
–V
OUT
V
IN
LT1031 LT1031
IN OUT
R1 = R1
OUT
GND GND
LT1031 • TA01
OUTPUT ACCURACY (%)
–0.10
PERCENT OF UNITS (%)
15
20
25
00.06
LT1031 TA02
10
5
0–0.06 –0.02 0.02
30
35
40
0.10
TA = 25°C
DISTRIBUTION
FROM 5 RUNS
TYPICAL APPLICATIO
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*See LH0070 Electrical Characteristics table and AD581 cross reference guide.
2
LT1031/LH0070
1031fb
Input Voltage ........................................................... 40V
Input-Output Voltage Differential ............................. 35V
Output to Ground Voltage
(Shunt Mode Current Limit)................................. 16V
Trim Pin to Ground Voltage
Positive ................................................. Equal to V
OUT
Negative ............................................................. –20V
Output Short-Circuit Duration
V
IN
= 35V ......................................................... 10 sec
V
IN
≤ 20V ..................................................... Indefinite
Operating Temperature Range
LT1031M .......................................... –55°C to 125°C
LT1031C .................................................. 0°C to 70°C
Lead Temperature (Soldering, 10 sec).................. 300°C
LT1031
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
R
Output Voltage (Note 2) LT1031B 9.995 10.000 10.005 V
LT1031C 9.990 10.000 10.010 V
LT1031D 9.980 10.000 10.020 V
∆V
R
Output Voltage Temperature T
MIN
≤ T
J
≤ T
MAX
∆T Coefficient (Note 3) LT1031B ●3 5 ppm/°C
LT1031C ●6 15 ppm/°C
LT1031D ●10 25 ppm/°C
∆V
R
Line Regulation (Note 4) 11.5V ≤ V
IN
≤ 14.5V 1 4 ppm/V
∆V
IN
●6 ppm/V
4.5V ≤ V
IN
≤ 40V 0.5 2 ppm/V
●4 ppm/V
∆V
R
Load Regulation (Sourcing Current) 0 ≤ I
OUT
≤ 10mA 12 25 ppm/mA
∆I
O
(Note 4) ●40 ppm/mA
∆V
R
Load Regulation (Shunt Mode) 1.7mA ≤ I
SHUNT
≤ 10mA 50 100 ppm/mA
∆I
O
(Notes 4, 5) ●150 ppm/mA
I
Q
Series Mode Supply Current 1.2 1.7 mA
●2.0 mA
I
MIN
Shunt Mode Minimum Current V
IN
is Open 1.1 1.5 mA
Output Short-Circuit Current 11V ≤ V
IN
≤ 35V 30 mA
Minimum Input Voltage (Note 7) l
OUT
≤ 1mA 10.8 11.0 V
e
n
Output Voltage Noise 0.1Hz ≤ f ≤ 10Hz 6 µV
P-P
10Hz ≤ f ≤ 10kHz 11 µV
RMS
∆V
R
Long Term Stability of ∆t = 1000 Hrs 15 ppm
∆Time Output Voltage Non-Cumulative
Temperature Hysteresis of Output ∆T = 50°C 5 ppm
ABSOLUTE AXI U RATI GS
WWWU
(Note 1)
PACKAGE/ORDER I FOR ATIO
UU
W
(LT1031) The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, I
OUT
= 0, Mil or Comm version, unless noted.
ELECTRICAL CHARACTERISTICS
ORDER PART NUMBER
LH0070-0H
LH0070-1H
LH0070-2H
BOTTOM VIEW
INPUT
1
2
3
OUTPUT
GROUND
H PACKAGE
3-LEAD TO-39 METAL CAN
TJMAX = 150°C, θJA = 150°C/W, θJC = 45°C/W (LH0070)
TJMAX = 150°C, θJA = 150°C/W, θJC = 45°C/W (LT1031M)
TJMAX = 85°C, θJA = 150°C/W, θJC = 45°C/W (LT1031C)
LT1031BMH
LT1031DMH
LT1031BCH
LT1031CCH
LT1031DCH
3
LT1031/LH0070
1031fb
(LH0070) The ● denotes the specifications which apply over the full
operating temperature range. VIN = 15V, RL = 10kΩ, –55°C ≤ TA ≤ 125°C, unless noted.
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Output voltage is measured immediately after turn-on. Changes
due to chip warm-up are typically less than 0.005%.
Note 3: Temperature coefficient is measured by dividing the change in
output voltage over the temperature range by the change in temperature.
Separate tests are done for hot and cold: T
MIN
to 25°C and 25°C to T
MAX
.
Incremental slope is also measured at 25
°
C. For LT1031BMH, the
5ppm/°C drift specification is for –25°C to 85°C. Drift over the full –55°C
to 125°C range is guaranteed to 7ppm/°C.
Note 4: Line and load regulation are measured on a pulse basis. Output
changes due to die temperature change must be taken into account
separately. Package thermal resistance is 150°C/W.
Note 5: 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 6: Temperature drift is guaranteed from –25°C to 85°C on LH0070.
Note 7: See curve for guaranteed minimum V
IN
versus I
OUT
.
Note 8: Guaranteed by design.
LH0070
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
R
Output Voltage T
A
= 25°C 10.000 V
∆V
R
Output Accuracy T
A
= 25°C
– 0, –1 ± 0.03 ± 0.1 %
– 2 ± 0.02 ± 0.05 %
∆V
R
Output Accuracy T
A
= –55°C, 125°C
– 0, –1 ●0.3 %
– 2 0.2 %
∆V
R
Output Voltage Change Note 6
∆T with Temperature
– 0 ●± 0.2 %
– 1 ●± 0.02 ± 0.1 %
– 2 ●± 0.01 ± 0.04 %
∆V
R
Line Regulation 13V ≤ V
IN
≤ 33V, T
A
= 25°C
∆V
IN
– 0, –1 0.006 0.1 %
– 2 0.006 0.03 %
Input Voltage Range ●11.4 40 V
∆V
R
Load Regulation 0mA ≤ l
OUT
≤ 5mA ●0.01 0.03 %
∆I
O
I
Q
Quiescent Current 13V ≤ V
IN
≤ 33V ●1.2 5 mA
∆l
Q
Change in Quiescent Current ∆V
IN
= 20V from 13V TO 33V ●0.1 1.5 mA
∆V
IN
e
n
Output Noise Voltage 6 µV
P-P
Ripple Rejection f = 120Hz ●0.001 %/V
P-P
r
O
Output Resistance ●0.2 0.6 Ω
∆V
Z
Long Term Stability T
A
= 25°C (Note 8)
∆Time – 0, –1 ± 0.2 %/Yr
– 2 ± 0.05 %/Yr
4
LT1031/LH0070
1031fb
TYPICAL PERFOR A CE CHARACTERISTICS
UW
The following cross reference guide may be used to select
LT1031 grades which meet or exceed output voltage,
temperature drift, load and line regulation, and output
current specifications of the AD581 reference. Parameters
such as noise, hysteresis, and long term stability will be
significantly better for all LT1031 grades compared to the
AD581.
Ripple Rejection Minimum Input VoltageRipple Rejection
INPUT VOLTAGE (V)
0
85
REJECTION (dB)
90
95
100
105
10 20 30 40
LT1031 • TPC01
110
115
51525 35
f = 150Hz
OUTPUT CURRENT (mA)
0
INPUT VOLTAGE (V)
11.6
11.4
11.2
11.0
10.8
10.6
10.4
10.2
10.0
16
LT1031 • TPC03
4 8 12 20142 6 10 18
GUARANTEED
CURVE-ALL
TEMPS
T
J
= 25°C
T
J
= 125°C
T
J
= –55°C
LT1031 • TPC02
FREQUENCY (Hz)
10
90
REJECTION (dB)
110
130
100 1k 10k
70
80
100
120
60
50
V
IN
= 15V
C
OUT
= 0
Start-Up (Series Mode) Start-Up (Shunt Mode) Output Voltage Noise Spectrum
TIME (µs)
3
OUTPUT VOLTAGE (V)
4
6
7
8
13
10
268
LT1031 • TPC04
5
11
12
9
04 10 12 14
V
IN
= 0 TO 12V
LT1031 • TPC06
FREQUENCY (Hz)
10
200
NOISE VOLTAGE (nV/√Hz)
300
400
100 1k 10k
100
150
250
350
50
0
CROSS REFERENCE
U
TIME (µs)
OUTPUT VOLTAGE (V)
9
10
11
48
8
7
02 61012
6
5
LT1031 • TPC05
NC
0V
–12V
GND
IN
V
OUT
OUT
1k
CROSS REFERENCE GUIDE/LT1031 TO AD581
AD581J order LT1031DCH
AD581K order LT1031CCH
AD581L order LT1031BCH
A0581S order LT1031DMH
A0581U order LT1031BMH
5
LT1031/LH0070
1031fb
Output Voltage Noise Load Regulation
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Output Voltage Temperature
LT1031 • TPC07
BANDWIDTH (Hz)
10
8
RMS NOISE (µV)
12
16
100 1k 10k
4
6
10
14
2
0
COUT = 0
FILTER = 1 POLE
fLOW = 0.1Hz
SOURCING
OUTPUT CURRENT (mA)
SINKING
–10
OUTPUT CHANGE (mV)
1
3
2
0
–2
–4
5
4
6
–1
–3
–5 –6–8 –2–4 24 8
010
LT1031 • TPC08
V
IN
= 12V
TEMPERATURE (˚C)
–50
OUTPUT VOLTAGE (V)
10.002
10.004
10.006
25 75
10.000
9.998
–25 0 50 100 125
9.996
9.994
LT1031 • TPC09
Input Supply Current Shunt Mode Current LimitShunt Characteristics
INPUT VOLTAGE (V)
05
INPUT CURRENT (mA)
1.0
1.2
1.4
35 40
0.8
0.6
0.2
0
10 15 20 25 30
0.4
1.8
1.6
LT1031 • TPC10
I
OUT
= 0
T
J
= 125°C
T
J
= –55°C
T
J
= 25°C
OUTPUT TO GROUND VOLTAGE (V)
0
0
CURRENT INTO OUTPUT (mA)
0.2
0.6
0.8
1.0
8
1.8
0.4
42 6 10 12
1.2
1.4
1.6
LT1031 • TPC11
INPUT PIN OPEN
TJ = 125°C
TJ = –55°C
TJ = 25°C
OUTPUT VOLTAGE (V)
0
0
CURRENT INTO OUTPUT (mA)
10
30
40
50
4810 18
20
26 12 14 16
60
LT1031 • TPC12
INPUT PIN IS OPEN
Thermal Regulation
Load Transient Response
CLOAD = 0
Load Transient Response
CLOAD = 1000pF
TIME (µs)
OUTPUT VOLTAGE CHANGE
4
20 64 02 6
88
LT1031 • TPC15
NOTE VERTICAL SCALE CHANGE
BETWEEN SOURCING AND SINKING
I
SINK
= 2 TO 10mA
I
SOURCE
= 0
I
SINK
= 1.4mA
I
SINK
= 1.2mA
∆I
SOURCE
= 100µAp-p
I
SOURCE
= 0.5mA
I
SOURCE
= 2 TO 10mA
∆I
SINK
= 100µAp-p
5mV
20mV
I
SINK
= 0.8mA
TIME (ms)
*INDEPENDENT OF TEMPERATURE COEFFICIENT
OUTPUT CHANGE (mV)
–1.0
0
140
20–20 60 100
040 80 120
–1.5
–0.5
LT1031 • TPC13
I
LOAD
= 10mA
V
IN
= 30V
∆POWER = 200mW
LOAD
REGULATION
THERMAL*
REGULATION
TIME (µs)
OUTPUT VOLTAGE CHANGE
7
10–2 32 56 8
49
LT1031 • TPC14
NOTE VERTICAL SCALE CHANGE
BETWEEN SOURCING AND SINKING
I
SINK
= 2 TO 10mA
I
SOURCE
= 0
I
SINK
= 1.0mA
I
SINK
= 0.8mA
∆I
SOURCE
= 100µAp-p
I
SOURCE
= 0.2mA
I
SOURCE
= 2 TO 10mA
I
SINK
= 0.6mA
∆I
SINK
= 100µAp-p
10mV
50mV
6
LT1031/LH0070
1031fb
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Output Noise 0.1Hz to 10Hz
TIME (MINUTES)
035
12 46
OUTPUT VOLTAGE NOISE (10µV/DIV)
LT1031 • TPC16
10µV (1ppm)
FILTERING = 1 ZERO AT 0.1Hz
2 POLES AT 10Hz
APPLICATIO S I FOR ATIO
WUUU
Trimming Output Voltage
The LT1031 output can be trimmed by driving the ground
pin. The suggested method is shown in the illustration
below. A 5Ω resistor is inserted in series with the ground
pin. The top of the resistor is supplied current from a trim
potentiometer. This technique requires fairly high trim
current of up to 1.5mA from the LT1031 or 3.5mA from the
–15V supply; however it is necessary to maintain low drift
in the reference. Ground pin current changes in the LT1031,
with temperature, could be as high as 4µA/°C.
This,
coupled with the 5Ω external resistor, creates up
to 2ppm/°C drift in the reference (5Ω • 4µA/°C = 20µV/°C
= 2ppm/°C). If induced drift higher than this can be
tolerated, all resistor values in the trim circuit can be raised
proportionately to reduce current drain.
Output Voltage Trimming
LT1031 • TA04
–15V
*CAN BE INCREASED TO 5.6k FOR
LT1031B AND LH0070-2
**INCREASE TO 10Ω FOR LT1031D
R3
50k
R2*
4.3k
R1**
5Ω
VIN VOUT
LT1031
GND
IN OUT
Effect of Reference Drift on System Accuracy
A large portion of the temperature drift error budget in
many systems is the system reference voltage. The graph
below indicates the maximum temperature coefficient
allowable if the reference is to contribute no more than
1/2LSB 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. The graph shows that the
temperature coefficient of the reference must be no worse
than 3ppm/°C if it is to contribute less than 1/2LSB error.
For this reason, the LT1031 has been optimized for low
drift.
Maximum Allowable Reference Drift
TEMPERATURE SPAN (°C)
10
MAXIMUM TEMPERATURE COEFFICIENT FOR
1/2LSB ERROR (ppm/°C)
30
100
1.0
10
20 100
90
807060
50
40
LT1031 • TA03
14-BIT
12-BIT
10-BIT
8-BIT
7
LT1031/LH0070
1031fb
APPLICATIO S I FOR ATIO
WUUU
Standard Series Mode
LT1031 • TA05
INPUT
LOAD
+
KEEP THIS LINE RESISTANCE LOW
GROUND
RETURN
LT1031
GND
IN OUT
Capacitive Loading and Transient Response
The LT1031 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 worst-case at light load currents.
Because of internal current drain on the output, actual
worst-case occurs at I
LOAD
= 1.4mA (sinking).
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.
Kelvin Connections
Although the LT1031 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
LT1031 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 LT1031 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 (especially kovar lead TO-5) and
printed circuit board materials and/or sockets. Power
dissipation in the reference, even though it rarely exceeds
20mW, is enough to cause small temperature gradients in
the package leads. Variations in thermal resistance, caused
by uneven airflow, create differential lead temperatures,
thereby causing thermoelectric voltage noise at the output
of the reference. The XY plotter trace shown on the
following page dramatically illustrates this effect. The first
half of the plot was done with the LT1031 shielded from
ambient air with a small foam cup. The cup was then
removed for the second half of the trace. Ambient in both
cases was a lab environment with no excessive air turbu-
lence from air conditioners, opening/closing doors, etc.
Removing the foam cup increases the output noise by
almost an order of magnitude in the 0.01Hz to 1Hz band!
The kovar leads of the TO-5 (H) package are the primary
culprit. Alloy 42 and copper lead frames used on dual-in-
line packages are not nearly as sensitive to thermally
generated noise because they are intrinsically matched.
Series Mode with Boost Transistor
LT1031
GND
OUT
IN
2N3906
INPUT
LOAD
*OPTIONAL—REDUCES CURRENT IN OUTPUT SENSE LEAD
GROUND
RETURN
R1
220Ω
R2*
5.6k
LT1031 • TA06
8
LT1031/LH0070
1031fb
APPLICATIO S I FOR ATIO
WUUU
Noise Induced by Air Turbulence
(TO-5 Package)
TIME (MINUTES)
20µV
0610
LT1031 • TA07
24 812
OUTPUT VOLTAGE NOISE (20µV/DIV)
FOAM CUP REMOVED
(TO-5 PACKAGE)
f = 0.01Hz to 10Hz
There is nothing magical about foam cups—any
enclosure which blocks air flow from the reference will do.
Smaller enclosures are better since they do not allow the
build-up of internally generated air movement. Naturally,
heat generating components external to the reference
itself should not be included inside the enclosure.
Boosted Output Current with No Current LimitNegative Series Reference
R1
4.7k
R2
4.7k
D1
15V
Q1
2N2905
–10V
AT 50mA
LT1031 • AC01
–15V
15V
LT1031
GND
IN OUT
Boosted Output Current with Current Limit
LT1031
GND
OUT
IN
LT1031 • AC04
15V 30mA
TYPICAL LOAD
CURRENT = 30mA
*SELECT R1 TO DELIVER TYPICAL LOAD CURRENT
LT1031 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
R1*
169Ω
VOUT = 10V
RL
Handling Higher Load Currents
LT1031
GND
OUT
IN
2N2905
V+ ≥ 11.8V
R1
220Ω
10V
AT 100mA
2µF
SOLID
TANT
LT1031 • AC02
+
APPLICATIO CIRCUITS
U
LT1031
GND
OUT
IN
2N2905
*GLOWS IN CURRENT LIMIT
DO NOT OMIT
8.2Ω
R1
220Ω
D1*
LED
V
+
≥ 12.8V
10V
AT 100mA
2µF
SOLID
TANT
LT1031 • AC03
+
9
LT1031/LH0070
1031fb
Strain Gauge Conditioner
for 350Ω Bridge
Ultralinear Platinum Temperature Sensor*
APPLICATIO CIRCUITS
U
–
+
LT1031
GND
OUT IN 20V
20V
–15V
–15V
2
3
7
4
6VOUT = 100mV/°C
–50°C ≤ T ≤ 150°C
R2*
5k
R14
5k
R12
1k
R15
10k
R13
24.3k
R10
182k
1% R11
6.65M
1%
R5
200k
1%
R6
619k
1%
R4
4.75k
1%
R7
392k
1%
RS
†
100Ω
AT 0°C
R1**
253k
R8
10M
R9
100k
R3**
5k
Rf**
654k
STANDARD INDUSTRIAL 100Ω PLATINUM 4-WIRE SENSOR, ROSEMOUNT 78S,
OR EQUIVALENT. α = 0.00385
TRIM R9 FOR VOUT = 0 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 NON-INTERACTIVE SO THAT ONLY ONE
TRIM SEQUENCE IS NORMALLY REQUIRED.
FEEDBACK LINEARIZES OUTPUT TO ±0.005°C FROM – 50°C TO 150°C
WIREWOUND RESISTORS WITH LOW TC
†
*
**
LT1031 • AC06
LT1001
–
+
R2
20k
R4
20k
R1
357Ω
1/2W
357Ω
1/2W
R6
2MΩ*
R3
2MΩ
R5
2M
350Ω STRAIN
GUAGE BRIDGE**
LT1031 • AC05
5V
–5V
100pF
VOUT • 100
66
8
1
3
3
2
2
28mA
28.5mA
15V
–15V
LT1031
LT1012CLM301A
†
GND
IN OUT
–
+
THIS RESISTOR PROVIDES POSITIVE FEEDBACK TO THE BRIDGE TO ELIMINATE
LOADING EFFECT OF THE AMPLIFIER. EFFECTIVE ZIN OF AMPLIFIER STAGE IS
≥ 1MΩ. IF R2–R5 ARE CHANGED, SET R6 = R3
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 DIFERENTIAL
CONNECTION OF LT1012C
*
**
†
10
LT1031/LH0070
1031fb
APPLICATIO CIRCUITS
U
Negative Shunt Reference Driven
by Current Source
LT1031 • AC08
LM334
2.5mA
27Ω
–10V (I
LOAD
≤ 1mA)
–11V TO –40V
LT1031
OUT
GND
2-Pole Lowpass Filtered Reference
–
+
LT1031 • AC07
R1
36k
R2
36k
MYLAR
1µF
f = 10Hz
V
IN
V
IN
+V
REF
–V
REF
0.5µF
MYLAR
TOTAL NOISE
≤ 2µV
RMS
1Hz ≤ f ≤ 10kHz
LT1031 LT1001
GND
IN OUT
11
LT1031/LH0070
1031fb
D4
6.3V
INPUT
OUTPUT
D1
D2
D3
Q1
Q2
GND
Q3
R2
R1
LT1031 • ES01
–+
A1
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 represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
EQUIVALENT SCHEMATIC
UW
APPLICATIO CIRCUITS
U
Precision DAC Reference with System TC Trim
LT1031 • AC09
1.24k
1%
200k
1%
8.87k
1%
10k
1%
10.36k
1%
10k
1%
15V
D1
IN457
D2
IN457
50k
TC TRIM*
DAC
*TRIMS 1mA REFERENCE CURRENT
TC BY ±40ppm/°C. THIS TRIM
SCHEME HAS VERY LITTLE EFFECT ON ROOM
TEMPERATURE CURRENT TO MINIMIZE ITERATIVE
TRIMMING.
LT1031
GND
IN OUT
50k
1mA 8.45k
50k
ROOM TEMP
TRIM
12
LT1031/LH0070
1031fb
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
LT 1105 REV B • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 2005
U
PACKAGE DESCRIPTIO
H Package
3-Lead TO-39 Metal Can
(Reference LTC DWG # 05-08-1330)
.016 – .019**
(0.406 – 0.483)
DIA
.050
(1.270)
MAX .165 – .185
(4.191 – 4.699)
.500
(12.700)
MIN
.305 – .335
(7.747 – 8.509)
.350 – .370
(8.890 – 9.398)
.200
(5.080)
TYP
45°
H3(TO-39) 0801
.100
(2.540)
.100
(2.540)
.029 – .045
(0.737 – 1.143)
.028 – .034
(0.711 – 0.864)
REFERENCE
PLANE *
LEAD DIAMETER IS UNCONTROLLED BETWEEN THE REFERENCE PLANE
AND .050" BELOW THE REFERENCE PLANE
FOR SOLDER DIP LEAD FINISH, LEAD DIAMETER IS .016 – .024
(0.406 – 0.610)
*
**
PIN 1
