LT1236
Precision Reference
FEATURES
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s
s
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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 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.
, 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
V
IN
IN
GND
OUT
V
OUT
NC
LT1236-10
IN
GND
–V
OUT
V
– (V
–
)
R1 =
OUT
I
LOAD
+ 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
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
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
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
TOP VIEW
NC* 1
V
IN
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*
V
0UT
TRIM**
T
JMAX
= 125°C,
θ
JA
= 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
V
IN
= 10V, I
OUT
= 0, T
A
= 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
T
MIN
≤
T
J
≤
T
MAX
LT1236A-5
LT1236B-5
LT1236C-5
7.2V
≤
V
IN
≤
10V
10V
≤
V
IN
≤
40V
q
Line Regulation (Note 3)
Load Regulation (Sourcing Current)
(Note 3)
0
≤
I
OUT
≤
10mA
q
2
U
U
W
W W
U
W
ORDER PART
NUMBER
TOP VIEW
NC* 1
V
IN
2
NC* 3
GND 4
8
7
6
5
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
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
T
JMAX
= 125°C,
θ
JA
= 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
V
IN
= 10V, I
OUT
= 0, T
A
= 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
µV
P-P
µV
RMS
ppm
ppm
0
≤
I
OUT
≤
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
V
IN
= 15V, I
OUT
= 0, T
A
= 25°C, unless otherwise noted.
PARAMETER
Output Voltage (Note 1)
Output Voltage Temperature Coefficient (Note 2)
CONDITIONS
LT1236A-10
LT1236B-10/LT1236C-10
T
MIN
≤
T
J
≤
T
MAX
LT1236A-10
LT1236B-10
LT1236C-10
11.5V
≤
V
IN
≤
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
µV
P-P
µV
RMS
ppm
ppm
Line Regulation (Note 3)
14.5V
≤
V
IN
≤
40V
q
Load Regulation (Sourcing Current)
(Note 3)
Load Regulation (Shunt Mode)
(Notes 3, 4)
Series Mode Supply Current
0
≤
I
OUT
≤
10mA
q
12
50
q
1.7mA
≤
I
SHUNT
≤
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)
V
IN
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
V
IN
= 15V, I
OUT
= 0, T
A
= 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
V
IN
= 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
U W
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
T
J
= 125
°C
T
J
= –55
°C
T
J
= 25
°C
V
IN
= 15V
C
OUT
= 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
V
OUT
+ 2V
1k
V
OUT
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
C
OUT
= 0
FILTER = 1 POLE
f
LOW
= 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)
I
OUT
= 0
INPUT CURRENT (mA)
1.2
T
J
= – 55°C
1.0
0.8
0.6
0.4
0.2
0
0
5
10
15 20 25 30
INPUT VOLTAGE (V)
35
40
T
J
= 25°C
T
J
= 125°C
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, C
LOAD
= 0
I
SOURCE
= 0
I
SINK
= 0
OUTPUT VOLTAGE NOISE (5µV/DIV)
OUTPUT CHANGE (50mV/DIV)
OUTPUT CHANGE (20mV/DIV)
50mV
50mV
I
SOURCE
= 0.5mA
I
SOURCE
= 2-10mA
I
SINK
= 0.2mA
I
SINK
= 2-10mA
∆I
SOURCE
= 100µA
P-P
0
1
2
∆I
SINK
= 100µA
P-P
1
2
3
4
3 4 0
TIME (µs)
U W
LT1236 G10
Output Voltage Temperature Drift
LT1236-5
5
4
5.004
Load Regulation LT1236-5
V
IN
= 8V
3
2
1
0
–1
–2
–3
–4
5.003
5.002
5.001
5.000
–40 –20
40
20
60
0
TEMPERATURE (°C)
80
100
–5
–10 – 8 – 6 – 4 – 2
SOURCING
0
2
4 6 8
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
V
IN
= 25V
∆POWER
= 200mW
LOAD
REGULATION
THERMAL
REGULATION*
V
IN
= 8V
I
LOAD
= 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, C
LOAD
= 1000pF
I
SOURCE
= 0
I
SINK
= 0
Output Noise 0.1Hz to 10Hz,
LT1236-5
FILTERING = 1 ZERO AT 0.1Hz
2 POLES AT 10Hz
5µV (1ppm)
20mV
20mV
I
SOURCE
= 0.2mA
I
SINK
= 0.2mA
I
SINK
= 2-10mA
I
SOURCE
= 2-10mA
∆I
SOURCE
= 100µA
P-P
0
5
∆I
SINK
= 100µA
P-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
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