1
LT1236
Precision Reference
U
A
O
PPLICATITYPICAL
D
U
ESCRIPTIO
The LT
®
1236 is a precision reference that combines ultra-
low 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 characteris-
tics 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 tem-
perature 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.
S
FEATURE
■
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
, LTC and LT are registered trademarks of Linear Technology Corporation.
Typical Distribution of Temperature Drift
Basic Positive and Negative Connections
LT1236
OUT
IN
GND
LT1236-10
OUT
IN
GND
V
OUT
–V
OUT
V
IN
NC
R1 = V
OUT
– (V
–
)
I
LOAD
+ 1.5mA
–15V
(V
–
)
R1
LT1236 TA01
OUTPUT DRIFT (ppm/°C)
–3
0
UNITS (%)
4
8
12
16
24
22
–2 –1 0 1
LT1236 TA02
23
20
18
14
10
6
2
DISTRIBUTION 
OF THREE RUNS
U
S
A
O
PPLICATI
■
A/D and D/A Converters
■
Precision Regulators
■
Precision Scales
■
Inertial Navigation Systems
■
Digital Voltmeters
2
LT1236
1
2
3
4
8
7
6
5
TOP VIEW
NC*
V
IN
NC*
GND
NC*
NC*
V
0UT
TRIM**
S8 PACKAGE
8-LEAD PLASTIC SO
CONNECTED INTERNALLY. 
D0 NOT CONNECT EXTERNAL
CIRCUITRY TO THESE PINS
SEE APPLICATIONS
INFORMATION SECTION
*
**
A
U
G
W
A
W
U
W
ARBSOLUTEXI T
I
S
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 V
OUT
Negative ........................................................... – 20V
Output Short-Circuit Duration
V
IN
= 35V......................................................... 10 sec
V
IN
≤ 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
WU
U
PACKAGE/ORDER I FOR ATIO
Consult factory for Military grade parts.
ELECTRICAL C CHARA TERISTICS
VIN = 10V, IOUT = 0, TA = 25°C, unless otherwise noted.
LT1236-5
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage (Note 1) LT1236A-5 4.9975 5.000 5.0025 V
LT1236B-5/LT1236C-5 4.9950 5.000 5.0050 V
Output Voltage Temperature Coefficient (Note 2) T
MIN
≤ T
J
≤ T
MAX
LT1236A-5 2 5 ppm/°C
LT1236B-5 5 10 ppm/°C
LT1236C-5 10 15 ppm/°C
Line Regulation (Note 3) 7.2V ≤ V
IN
≤ 10V 4 12 ppm/V
●20 ppm/V
10V ≤ V
IN
≤ 40V 2 6 ppm/V
●10 ppm/V
Load Regulation (Sourcing Current) 0 ≤ I
OUT
≤ 10mA 10 20 ppm/mA
(Note 3) ●35 ppm/mA
LT1236AIS8-5
LT1236BIS8-5
LT1236CIS8-5
LT1236AIS8-10
LT1236BIS8-10
LT1236CIS8-10
ORDER PART
NUMBER
S8 PART MARKING
LT1236ACS8-5
LT1236BCS8-5
LT1236CCS8-5
LT1236ACS8-10
LT1236BCS8-10
LT1236CCS8-10
236AC5
236BC5
236CC5
236AC1
236BC1
236CC1
236AI5
236BI5
236CI5
236AI1
236BI1
236CI1
T
JMAX
= 125°C, θ
JA
= 190°C/WT
JMAX
= 125°C, θ
JA
= 130°C/W
ORDER PART
NUMBER
LT1236ACN8-5
LT1236BCN8-5
LT1236CCN8-5
LT1236ACN8-10
LT1236BCN8-10
LT1236CCN8-10
LT1236AIN8-5
LT1236BIN8-5
LT1236CIN8-5
LT1236AIN8-10
LT1236BIN8-10
LT1236CIN8-10
1
2
3
4
8
7
6
5
TOP VIEW
NC*
V
IN
NC*
GND
NC*
NC*
V
0UT
TRIM**
N8 PACKAGE
8-LEAD PDIP
CONNECTED INTERNALLY. 
D0 NOT CONNECT EXTERNAL
CIRCUITRY TO THESE PINS
SEE APPLICATIONS
INFORMATION SECTION
*
**
3
LT1236
ELECTRICAL C CHARA TERISTICS
VIN = 10V, IOUT = 0, TA = 25°C, unless otherwise noted.
LT1236-10
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage (Note 1) LT1236A-10 9.995 10.000 10.005 V
LT1236B-10/LT1236C-10 9.990 10.000 10.010 V
Output Voltage Temperature Coefficient (Note 2) T
MIN
≤ T
J
≤ T
MAX
LT1236A-10 2 5 ppm/°C
LT1236B-10 5 10 ppm/°C
LT1236C-10 10 15 ppm/°C
Line Regulation (Note 3) 11.5V ≤ V
IN
≤ 14.5V 1.0 4 ppm/V
●6 ppm/V
14.5V ≤ V
IN
≤ 40V 0.5 2 ppm/V
●4 ppm/V
Load Regulation (Sourcing Current) 0 ≤ I
OUT
≤ 10mA 12 25 ppm/mA
(Note 3) ●40 ppm/mA
Load Regulation (Shunt Mode) 1.7mA ≤ I
SHUNT
≤ 10mA 50 100 ppm/mA
(Notes 3, 4) ●150 ppm/mA
Series Mode Supply Current 1.2 1.7 mA
●2.0 mA
Shunt Mode Minimum Current V
IN
is Open 1.1 1.5 mA
●1.7 mA
Output Voltage Noise (Note 5) 0.1Hz ≤ f ≤ 10Hz 6.0 µV
P-P
10Hz ≤ f ≤ 1kHz 3.5 6 µV
RMS
Long-Term Stablility of Output Voltage (Note 6) ∆t = 1000Hrs Non-Cumulative 30 ppm
Temperature Hysteresis of Output (Note 7) ∆T = ±25°C 5 ppm
VIN = 15V, IOUT = 0, TA= 25°C, unless otherwise noted.
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
The ● 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.
LT1236-5
PARAMETER CONDITIONS MIN TYP MAX UNITS
Load Regulation (Sinking Current) 0 ≤ I
OUT
≤ 10mA 60 100 ppm/mA
(Note 3) ●150 ppm/mA
Supply Current 0.8 1.2 mA
●1.5 mA
Output Voltage Noise 0.1Hz ≤ f ≤ 10Hz 3.0 µV
P-P
(Note 5) 10Hz ≤ f ≤ 1kHz 2.2 3.5 µV
RMS
Long-Term Stability of Output Voltage (Note 6) ∆t = 1000Hrs Non-Cumulative 20 ppm
Temperature Hysteresis of Output (Note 7) ∆T = ±25°C 10 ppm
4
LT1236
ELECTRICAL C CHARA TERISTICS
VIN = 15V, IOUT = 0, TA = 25°C, unless otherwise noted.
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
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.
CCHARA TERISTICS
UW
AT
Y
P
I
CALPER
F
O
RC
E
Ripple Rejection
INPUT VOLTAGE (V)
0
85
REJECTION (dB)
90
95
100
105
10 20 30 40
LT1236 G01
110
115
51525 35
f = 150Hz
LT1236-5
LT1236-10
FREQUENCY (Hz)
10
90
REJECTION (dB)
110
130
120
100
80
60
100 1k 10k
LT1236 G02
70
50
VIN = 15V
COUT = 0
LT1236-5
LT1236-10
Ripple Rejection Minimum Input/Output
Differential, LT1236-10
OUTPUT CURRENT (mA)
0
INPUT/OUTPUT VOLTAGE (V)
1.2
1.6
16
LT1236 G03
0.8
0.4
04812 20
1.0
1.4
0.6
0.2
14
2610 18
T
J
= 125 °C
T
J
= –55 °C
T
J
= 25 °C
Start-Up (Series Mode)
TIME (µs)
3
OUTPUT VOLTAGE (V)
4
6
7
8
13
10
268
LT1236 G04
5
11
12
9
04 10 12 14
LT1236-10
LT1236-5
V
IN
= 0V TO 12V
Start-Up (Shunt Mode), LT1236-10 Output Voltage Noise Spectrum
FREQUENCY (Hz)
100
NOISE VOLTAGE (nV/√Hz)
200
250
350
400
10 1k 1M
LT1236 G06
0100
300
150
50
LT1236-10
LT1236-5
TIME (µs)
OUTPUT VOLTAGE (V)
9
10
11
48
LT1236 G05
8
7
02 61012
6
5
LT1236-10
IN
GND
OUT
NC
1k V
OUT
0V
V
OUT
+ 2V
5
LT1236
CCHARA TERISTICS
UW
AT
Y
P
I
CALPER
F
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RC
E
Output Noise 0.1Hz to 10Hz,
LT1236-5
TIME (MINUTES)
0
35
LT1236 G15
12 46
OUTPUT VOLTAGE NOISE (5µV/DIV)
5µV (1ppm)
FILTERING = 1 ZERO AT 0.1Hz
2 POLES AT 10Hz
Output Voltage Noise
BANDWIDTH (Hz)
10
8
RMS NOISE (µV)
12
16
14
10
6
2
100 1k 10k
LT1236 G07
4
0
C
OUT
= 0
FILTER = 1 POLE
f
LOW
= 0.1Hz
LT1236-10
LT1236-5
Output Voltage Temperature Drift
LT1236-5
OUTPUT CURRENT (mA)
–10
OUTPUT CHANGE (mV)
1
3
5
4
2
0
–2
–4
6
LT1236 G09
–1
–3
–5 –6–8 –4 0 4 8
–2 210
V
IN
= 8V
SOURCING SINKING
Load Regulation LT1236-5
Quiescent Current, LT1236-5
INPUT VOLTAGE (V)
0
0
INPUT CURRENT (mA)
0.2
0.6
0.8
1.0
3530
1.8
LT1236 G10
0.4
5 10152025 40
1.2
1.4
1.6
T
J
= – 55°C
T
J
= 25°C
T
J
= 125°C
I
OUT
= 0
Thermal Regulation, LT1236-5
TIME (ms)
OUTPUT CHANGE (mV)
–1.0
– 0.5
140
LT1236 G12
20 60 100
0
040 80 120
LOAD
REGULATION
THERMAL 
REGULATION*
I
LOAD
= 10mA
*INDEPENDENT OF TEMPERATURE COEFFICIENT
V
IN
= 25V
∆POWER = 200mW
Sink Mode* Current Limit,
LT1236-5
OUTPUT VOLTAGE (V)
0
0
CURRENT INTO OUTPUT (mA)
10
30
40
50
4810 18
LT1236 G11
20
26 12 14 16
60 V
IN
= 8V
*NOTE THAT AN INPUT VOLTAGE IS REQUIRED 
FOR 5V UNITS.
Load Transient Response,
LT1236-5, CLOAD = 0
TIME (µs)
OUTPUT CHANGE (50mV/DIV)
2
LT1236 G13
102413
304
I
SOURCE
= 2-10mA
I
SOURCE
= 0.5mA
I
SINK
= 0
I
SINK
= 0.2mA
I
SINK
= 2-10mA
50mV 50mV
∆I
SINK
= 100µA
P-P
∆I
SOURCE
= 100µA
P-P
I
SOURCE
= 0
Load Transient Response,
LT1236-5, CLOAD = 1000pF
TIME (µs)
OUTPUT CHANGE (20mV/DIV)
10
LT1236 G14
501020515
15 020
I
SOURCE
= 2-10mA
I
SOURCE
= 0.2mA
I
SINK
= 0
I
SINK
= 0.2mA
I
SINK
= 2-10mA
20mV 20mV
∆I
SINK
= 100µA
P-P
∆I
SOURCE
= 100µA
P-P
I
SOURCE
= 0
TEMPERATURE (°C)
–40
5.000
OUTPUT VOLTAGE (V)
5.002
5.005
040 60
LT1236 G08
5.001
5.004
5.003
–20 20 80 100
6
LT1236
CCHARA TERISTICS
UW
AT
Y
P
I
CALPER
F
O
RC
E
Load Transient Response,
LT1236-10, CLOAD = 0 Load Transient Response,
LT1236-10, CLOAD = 1000pF Output Noise 0.1Hz to 10Hz,
LT1236-10
TIME (µs)
OUTPUT VOLTAGE CHANGE
2
LT1236 G22
102413
304
I
SOURCE
= 2-10mA
I
SOURCE
= 0.2mA
I
SINK
= 0.6mA
I
SINK
= 0.8mA
I
SINK
= 1.0mA
I
SINK
= 2-10mA
10mV
50mV
∆I
SINK
= 100µA
P-P
∆I
SOURCE
= 100µA
P-P
I
SOURCE
= 0
NOTE VERTICAL SCALE CHANGE
BETWEEN SOURCING AND SINKING
TIME (µs)
OUTPUT VOLTAGE CHANGE
2
LT1236 G23
102413
304
I
SOURCE
= 2-10mA
I
SOURCE
= 0.5mA
I
SINK
= 0.8mA
I
SINK
= 1.2mA
I
SINK
= 1.4mA
I
SINK
= 2-10mA
5mV
20mV
∆I
SINK
= 100µA
P-P
∆I
SOURCE
= 100µA
P-P
I
SOURCE
= 0
NOTE VERTICAL SCALE CHANGE
BETWEEN SOURCING AND SINKING
TIME (MINUTES)
0
35
LT1236 G24
12 46
OUTPUT VOLTAGE NOISE (10µV/DIV)
10µV (1ppm)
FILTERING = 1 ZERO AT 0.1Hz
2 POLES AT 10Hz
Output Voltage Temperature
Drift, LT1236-10
OUTPUT CURRENT (mA)
–10
OUTPUT CHANGE (mV)
1
3
5
4
2
0
–2
–4
6
LT1236 G17
–1
–3
–5 –6–8 –4 0 4 8
–2 210
V
IN
= 12V
SOURCING SINKING
Load Regulation, LT1236-10 Input Supply Current, LT1236-10
INPUT VOLTAGE (V)
0
0
INPUT CURRENT (mA)
0.2
0.6
0.8
1.0
3530
1.8
LT1236 G18
0.4
5 10152025 40
1.2
1.4
1.6 T
J
= – 55°C
T
J
= 25°C
T
J
= 125°C
I
OUT
= 0
Shunt Mode Current Limit,
LT1236-10
OUTPUT VOLTAGE (V)
0
0
CURRENT INTO OUTPUT (mA)
10
30
40
50
4810 18
LT1236 G20
20
26 12 14 16
60 INPUT PIN OPEN
Shunt Characteristics, LT1236-10
OUTPUT TO GROUND VOLTAGE (V)
0
0
CURRENT INTO OUTPUT (mA)
0.2
0.6
0.8
1.0
8
1.8
LT1236 G19
0.4
42 6 10 12
1.2
1.4
1.6
T
J
= – 55°C
T
J
= 25°C
INPUT PIN OPEN
T
J
= 125°C
Thermal Regulation, LT1236-10
TIME (ms)
OUTPUT CHANGE (mV)
–1.0
–0.5
0
140
LT1236 G21
–1.5
20 60 100
040 80 120
LOAD
REGULATION
THERMAL 
REGULATION*
I
LOAD
= 10mA
*INDEPENDENT OF TEMPERATURE COEFFICIENT
V
IN
= 30V
∆POWER = 200mW
TEMPERATURE (˚C)
–40
OUTPUT VOLTAGE (V)
10.0010
10.0015
10.0020
40
LT1236 G16
10.0005
10.0000
080–20 6020 100
9.9995
9.9990
9.9985
9.9980
7
LT1236
APPLICATIONS INFORMATION
WUU U
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 calibra-
tion is performed at 25°C, the temperature span is 40°C.
It can be seen from the graph that the temperature coeffi-
cient 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
TEMPERATURE SPAN (°C)
10
MAXIMUM TEMPERATURE COEFFICIENT FOR 
0.5LSB ERROR (ppm/°C)
30
100
LT1236 AI01
1.0
10
20 100
90
807060
50
40
8-BIT
10-BIT
12-BIT
14-BIT
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 mini-
mize 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 recom-
mended, 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
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
OUT
IN
GND TRIM
R1
27k R2
50k
1N4148
V
OUT
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 I
LOAD
= 0 on LT1236-5 and I
LOAD
=
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 applica-
tions, a 10µF solid tantalum capacitor with several ohms
in series provides optimum output bypass.
8
LT1236
APPLICATIONS INFORMATION
WUU U
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 be-
tween 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
Series Mode with Boost Transistor
LT1236
OUT
GND
IN
LOAD
R1
220Ω
2N3906
R2*
INPUT
GROUND
RETURN
*OPTIONAL—REDUCES CURRENT IN OUTPUT SENSE 
LEAD: R2 = 2.4k (LT1236-5), 5.6k (LT1236-10)
LT1236 AI04
temperature gradients in the package leads. Variations in
thermal resistance, caused by uneven air flow, create
differential lead temperatures, thereby causing thermo-
electric voltage noise at the output of the reference.
Standard Series Mode
LT1236
OUT
IN
GND
KEEP THIS LINE RESISTANCE LOW
LOAD
+
INPUT
GROUND
RETURN
LT1236 AI03
TYPICAL APPLICATIONS
U
LT1236 TA10
LT1236A-10
OUT
IN
GND TRIM
R2
50k
10.000V
R1
75k
TRIM RANGE ≈ ±10mV
V
IN
Negative Series Reference
LT1236-10
OUT
IN
GND
LT1236 TA04
D1
15V
R1
4.7k
–10V AT
50mA
R2
4.7k
–15V
15V
Q1
2N2905
Restricted Trim Range for Improved
Resolution, 10V, “A” Version Only
LT1236 TA03
LT1236-10
OUT
IN
GND TRIM
V
IN
V
OUT
R1*
10k
CAN BE RAISED TO 20k FOR LESS
CRITICAL APPLICATIONS
*
LT1236-10 Full Trim Range (±0.7%)
9
LT1236
TYPICAL APPLICATIONS
U
Boosted Output Current
with No Current Limit
LT1236
OUT
V
+
≥ (V
OUT
+ 1.8V)
GND
IN
LT1236 TA05
+
2N2905
10V AT
100mA
2µF
SOLID
TANT
R1
220Ω
Boosted Output Current
with Current Limit
LT1236
OUT
GND
IN
LT1236 TA06
+
2N2905
10V AT
100mA
2µF
SOLID
TANT
D1*
LED
V+ ≥ VOUT + 2.8V
8.2Ω
R1
220Ω
GLOWS IN CURRENT LIMIT,
DO NOT OMIT
*
LT1236 TA17
LT1236-10
GND
+10V15V V
OUT
V
IN
LT1236-10
GND
–10V
–15V
V
OUT
V
IN
COM
I
LOAD
R1 –15V R1
=–10V
I
LOAD
+ 1.5mA
±10V Output Reference
LT1236-10
OUT
GND
IN
LT1236 TA07
R
L
30mA
15V
R1*
169Ω
V
OUT
10V
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
*
Operating 5V Reference from 5V Supply
Handling Higher Load Currents
LT1236-5
OUT
IN
GND
LT1236 TA15
++
1N914
1N914
≈8.5V
C2*
5µF
C1*
5µF
5V
REFERENCE
5V LOGIC
SUPPLY
CMOS LOGIC GATE**
f
IN
≥ 2kHz*
FOR HIGHER FREQUENCIES C1 AND C2 MAY BE DECREASED
PARALLEL GATES FOR HIGHER REFERENCE CURRENT LOADING
*
**
LT1236-10
TRIM
GND
OUT
LT1236 TA14
–
+
1.2k
R2
40.2Ω
1%
R1
4.99k
1%
REF
CMOS
DAC
LTC7543
I
OUT
FB
30pF
LT1007C
R4*
100Ω
FULL-SCALE
ADJUST
R3
4.02K
1%
10V
F.S.
–15V
TC LESS THAN 200ppm/°C
NO ZERO ADJUST REQUIRED
WITH LT1007 (V
0S
≤ 60µV)
*
**
CMOS DAC with Low Drift Full-Scale Trimming**
Trimming 10V Units to 10.24V
LT1236-10
OUT
IN
TRIM GND
4.32k
V
OUT
= 10.24V
V
IN
5k
V
–
= –15V*
*MUST BE WELL REGULATED
dV
OUT
dV
–
=15mV
V
LT1236 TA11
10
LT1236
TYPICAL APPLICATIONS
U
LT1236-10
OUT
IN
GND
LT1236 TA16
15V
8.87k
1%
1.24k
1%
10k
1%
D1
1N457
50k 
TC TRIM*
10k
1%
D2
1N457
50k
200k
1%
50k
ROOM TEMP
TRIM 10.36k
1%
8.45k
1mA
TRIMS 1mA REFERENCE CURRENT 
TC BY ±40ppm/°C. THIS TRIM 
SCHEME HAS VERY LITTLE EFFECT ON ROOM
TEMPERATURE CURRENT TO MINIMIZE ITERATIVE
TRIMMING
*DAC
Precision DAC Reference with System TC Trim 2-Pole Lowpass Filtered Reference
Strain Gauge Conditioner for 350Ω Bridge
LT1236-10
OUT
IN
GND
LT1236 TA08
–
+
–
+
LM301A
†
100pF 8
1
6 6
3
2
–5V
357Ω
1/2W
–15V
R5
2M
R6*
2M
LT1012C
2
3
R4
20k
R2
20k
5V
R3
2M
V
OUT
X100
350Ω STRAIN
GAUGE BRIDGE**
28mA
28.5mA
R1
357Ω
1/2W
15V
THIS RESISTOR PROVIDES POSITIVE FEEDBACK TO 
THE BRIDGE TO ELIMINATE LOADING EFFECT OF 
THE AMPLIFIER. EFFECTIVE Z
IN
OF AMPLIFIER 
STAGE IS ≥ 1MΩ. IF R2 TO 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 DIFFERENTIAL CONNECTION OF LT1012C
**
†
Negative Shunt Reference Driven
by Current Source
LT1236
OUT
IN
GND
LT1236 TA12
–
+
R1
36k
1µF
MYLAR
0.5µF
MYLAR
R2
36k
LT1001
V
IN
V
IN
V
REF
–V
REF
f = 10Hz TOTAL NOISE 
≤2µV
RMS
1Hz ≤ f ≤ 10kHz
11
LT1236
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.
TYPICAL APPLICATIONS
U
Ultra-Linear Platinum Temperature Sensor*
EQUIVALE T SCHE ATIC
U W
D1
D2
D3 R1
R2
GND
LT1236 ES
Q1
Q2
D4
6.3V
OUTPUT
–+
A1
INPUT
Q3
LT1236-10
OUT IN
GND
LT1236 TA09
–
+
R
S
†
100Ω AT
0°C
R4
4.75k
1%
R5
200k
1%
R6
619k
1%
7
4
6
2
3LT1001
–15V
20V R13
24.3k
R12
1k
R15
10k
R14
5k
R
f
**
654k
R11
6.65M
1%
R10
182k
1%
R2*
5k
R1**
253k
R3**
5k
R9
100k
R8
10M
–15V
V
OUT
=100mV/°C
–50°C ≤ T ≤ 150°C
R7
392k
1%
20V
STANDARD INDUSTRIAL 100Ω PLATINUM 4-WIRE SENSOR,
ROSEMOUNT 78S OR EQUIVALENT. α = 0.00385
TRIM R9 FOR V
OUT
= 0V AT 0°C
TRIM R12 FOR V
OUT
= 10V AT 100°C
TRIM R14 FOR V
OUT
= 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
WIREWOUND RESISTORS WITH LOW TC
†
*
**
12
LT1236
LINEAR TECHNOLOGY CO RPORATION 1995
LT/GP 0695 10K • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900
●
FAX
: (408) 434-0507
●
TELEX
: 499-3977
PACKAGE DESCRIPTION
U
Dimensions in inches (millimeters) unless otherwise noted.
N8 Package
8-Lead Plastic DIP
N8 0395
0.045 ± 0.015
(1.143 ± 0.381)
0.100 ± 0.010
(2.540 ± 0.254)
0.065
(1.651)
TYP
0.045 – 0.065
(1.143 – 1.651)
0.130 ± 0.005
(3.302 ± 0.127)
0.015
(0.380)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
0.125
(3.175)
MIN
0.009 – 0.015
(0.229 – 0.381)
0.300 – 0.325
(7.620 – 8.255)
0.325 +0.025
–0.015
+0.635
–0.381
8.255
()
12 34
8765
0.255 ± 0.015*
(6.477 ± 0.381)
0.400*
(10.160)
MAX
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm).
S8 Package
8-Lead Plastic SOIC
SO8 0294
0.016 – 0.050
0.406 – 1.270
0.010 – 0.020
(0.254 – 0.508)× 45°
0°– 8° TYP
0.008 – 0.010
(0.203 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
0.014 – 0.019
(0.355 – 0.483)
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
1234
0.150 – 0.157*
(3.810 – 3.988)
8765
0.189 – 0.197*
(4.801 – 5.004)
0.228 – 0.244
(5.791 – 6.197)
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm).
PART NUMBER DESCRIPTION COMMENTS
LT1019 Precision Bandgap Reference 0.05%, 5ppm/°C
LT1027 Precision 5V Reference 0.02%, 2ppm/°C
RELATED PARTS