LT1021
Precision Reference
FEATURES
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DESCRIPTIO
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Pin Compatible with Most Bandgap Reference
Applications, Including Ref 01, Ref 02, LM368,
MC1400 and MC1404 with Greatly Improved
Stability, Noise and Drift
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/Output Differential of 1V
100% Noise Tested
The LT
®
1021 is a precision 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. Three
voltages are available: 5V, 7V and 10V. The 7V and 10V
units can be used as shunt regulators (two-terminal zeners)
with the same precision characteristics as the three-
terminal connection. Special care has been taken to mini-
mize thermal regulation effects and temperature
induced hysteresis.
The LT1021 references are based on a buried zener diode
structure that 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 bandgap references.
Unique circuit design makes the LT1021 the first IC
reference to offer ultralow drift without the use of high
power on-chip heaters.
The LT1021-7 uses no resistive divider to set output
voltage, and therefore exhibits the best long term stability
and temperature hysteresis. The LT1021-5 and LT1021-
10 are intended for systems requiring a precise 5V or 10V
reference with an initial tolerance as low as
±0.05%.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATI
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A/D and D/A Converters
Precision Regulators
Digital Voltmeters
Inertial Navigation Systems
Precision Scales
Portable Reference Standard
TYPICAL APPLICATI
Typical Distribution of Temperature Drift
Basic Positive and Negative Connections
LT1021
V
IN
IN
GND
OUT
V
OUT
NC
LT1021
(7 AND 10 ONLY)
OUT
GND
–V
OUT
R1 =
V
OUT
I
LOAD
+ 1.5mA
– (V
–
)
R1
–15V
(V
–
)
UNITS (%)
IN
24
21
18
15
12
9
6
3
1021 TA01
–0
– 5 – 4 – 3 – 2 –1 0 1 2 3
OUTPUT DRIFT (ppm/°C)
4
5
U
DISTRIBUTION
OF THREE RUNS
1021 TA01
UO
UO
1
LT1021
ABSOLUTE
AXI U
RATI GS
Input Voltage .......................................................... 40V
Input/Output Voltage Differential ............................ 35V
Output-to-Ground Voltage (Shunt Mode Current Limit)
LT1021-5 ............................................................. 10V
LT1021-7 ............................................................. 10V
LT1021-10 ........................................................... 16V
Trim Pin-to-Ground Voltage
Positive ............................................... Equal to V
OUT
Negative ........................................................... – 20V
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
LT1021BCH-5
LT1021BMH-5
LT1021CCH-5
LT1021CMH-5
LT1021DCH-5
LT1021DMH-5
LT1021BCH-7
LT1021BMH-7
LT1021DCH-7
LT1021DMH-7
LT1021BCH-10
LT1021BMH-10
LT1021CCH-10
LT1021CMH-10
LT1021DCH-10
LT1021DMH-10
TOP VIEW
NC*
8
NC* 1
V
IN
2
NC* 3
7 NC*
6
V
OUT
5 TRIM**
4
GND
H PACKAGE
8-LEAD TO-5 METAL CAN
*CONNECTED INTERNALLY.
D0 NOT CONNECT EXTERNAL
CIRCUITRY TO THESE PINS
**NO TRIM PIN ON LT1021-7.
DO NOT CONNECT EXTERNAL
CIRCUITRY TO PIN 5 ON LT1021-7
T
JMAX
= 150°C,
θ
JA
= 150°C/W,θ
JC
= 45°C/W
2
U
U
W
W W
U
W
(Note 1)
Output Short-Circuit Duration
V
IN
= 35V ......................................................... 10 sec
V
IN
≤
20V ................................................... Indefinite
Operating Temperature Range
Commercial ............................................ 0°C to 70°C
Industrial ........................................... – 40°C to 85°C
Military ............................................ – 55°C to 125°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................ 300°C
ORDER PART
NUMBER
LT1021BCN8-5
LT1021CCN8-5
LT1021CIN8-5
LT1021DCN8-5
LT1021DIN8-5
LT1021DCS8-5
LT1021BCN8-7
LT1021DCN8-7
LT1021DCS8-7
LT1021BCN8-10
LT1021CCN8-10
LT1021CIN8-10
LT1021DCN8-10
LT1021DCS8-10
LT1021DIN8-10
TOP VIEW
DNC* 1
V
IN
2
DNC* 3
GND 4
N8 PACKAGE
8-LEAD PDIP
8
7
6
5
DNC*
DNC*
V
0UT
TRIM**
S8 PACKAGE
8-LEAD PLASTIC SO
*CONNECTED INTERNALLY.
D0 NOT CONNECT EXTERNAL
CIRCUITRY TO THESE PINS
**NO TRIM PIN ON LT1021-7.
DO NOT CONNECT EXTERNAL
CIRCUITRY TO PIN 5 ON LT1021-7
T
JMAX
= 130°C,
θ
JA
= 130°C/W (N)
T
JMAX
= 130°C,
θ
JA
= 150°C/W (S)
S8 PART MARKING
2105
2107
2110
LT1021
The
q
denotes specifications that apply over the full operating temperature
range, otherwise specifications are T
A
= 25°C. V
IN
= 10V, I
OUT
= 0, unless otherwise noted.
PARAMETER
Output Voltage (Note 2)
Output Voltage Temperature Coefficient (Note 3)
CONDITIONS
LT1021C-5
LT1021B-5/LT1021D-5
T
MIN
≤
T
J
≤
T
MAX
LT1021B-5
LT1021C-5/LT1021D-5
7.2V
≤
V
IN
≤
10V
q
q
q
ELECTRICAL CHARACTERISTICS
MIN
4.9975
4.9500
LT1021-5
TYP
5.000
5.000
2
3
4
2
MAX
5.0025
5.0500
5
20
12
20
6
10
20
35
100
150
1.2
1.5
3.5
UNITS
V
V
ppm/°C
ppm/°C
ppm/V
ppm/V
ppm/V
ppm/V
ppm/mA
ppm/mA
ppm/mA
ppm/mA
mA
mA
µV
P-P
µV
RMS
ppm
ppm
Line Regulation (Note 4)
10V
≤
V
IN
≤
40V
q
Load Regulation (Sourcing Current)
Load Regulation (Sinking Current)
Supply Current
0
≤
I
OUT
≤
10mA
(Note 4)
0
≤
I
OUT
≤
10mA
(Note 4)
10
q
60
q
0.8
q
Output Voltage Noise (Note 6)
Long Term Stability of Output Voltage (Note 7)
Temperature Hysteresis of Output
0.1Hz
≤
f
≤
10Hz
10Hz
≤
f
≤
1kHz
∆t
= 1000Hrs Noncumulative
∆T
=
±25°C
3.0
2.2
15
10
The
q
denotes specifications that apply over the full operating temperature range, otherwise specifications are T
A
= 25°C.
V
IN
= 12V, I
OUT
= 0, unless otherwise noted.
PARAMETER
Output Voltage (Note 2)
Output Voltage Temperature Coefficient (Note 3)
T
MIN
≤
T
J
≤
T
MAX
LT1021B-7
LT1021D-7
8.5V
≤
V
IN
≤
12V
q
q
q
CONDITIONS
MIN
6.95
LT1021-7
TYP
7.00
2
3
1.0
2.0
0.5
1.0
12
MAX
7.05
5
20
4
8
2
4
25
40
100
150
1.2
1.5
1.0
1.2
4.0
UNITS
V
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 4)
12V
≤
V
IN
≤
40V
q
Load Regulation (Sourcing Current)
Load Regulation (Shunt Mode)
Supply Current (Series Mode)
0
≤
I
OUT
≤
10mA
(Note 4)
1.2mA
≤
I
SHUNT
≤
10mA
(Notes 4, 5)
q
50
q
0.75
q
Minimum Current (Shunt Mode)
Output Voltage Noise (Note 6)
Long Term Stability of Output Voltage (Note 7)
Temperature Hysteresis of Output
V
IN
is Open
q
0.7
4.0
2.5
7
3
0.1Hz
≤
f
≤
10Hz
10Hz
≤
f
≤
1kHz
∆t
= 1000Hrs Noncumulative
∆T
=
±25°C
3
LT1021
The
q
denotes specifications that apply over the full operating temperature
range, otherwise specifications are T
A
= 25°C. V
IN
= 15V, I
OUT
= 0, unless otherwise noted.
PARAMETER
Output Voltage (Note 2)
Output Voltage Temperature Coefficient (Note 3)
CONDITIONS
LT1021C-10
LT1021B-10/LT1021D-10
T
MIN
≤
T
J
≤
T
MAX
LT1021B-10
LT1021C-10/LT1021D-10
11.5V
≤
V
IN
≤
14.5V
q
q
q
ELECTRICAL CHARACTERISTICS
MIN
9.995
9.950
LT1021-10
TYP
10.00
10.00
2
5
1.0
0.5
MAX
10.005
10.050
5
20
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/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 4)
14.5V
≤
V
IN
≤
40V
q
Load Regulation (Sourcing Current)
Load Regulation (Shunt Mode)
Supply Current (Series Mode)
0
≤
I
OUT
≤
10mA
(Note 4)
1.7mA
≤
I
SHUNT
≤
10mA
(Notes 4, 5)
12
q
50
q
1.2
q
Minimum Current (Shunt Mode)
Output Voltage Noise (Note 6)
Long Term Stability of Output Voltage (Note 7)
Temperature Hysteresis of Output
V
IN
is Open
q
1.1
6.0
3.5
15
5
0.1Hz
≤
f
≤
10Hz
10Hz
≤
f
≤
1kHz
∆t
= 1000Hrs Noncumulative
∆T
=
±25°C
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.
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 for TO-5 (H), 130°C/W
for N and 150°C/W for the SO-8.
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:
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 correct for the non-ideal bandpass 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 7:
Consult factory for units with long term stability data.
4
LT1021
TYPICAL PERFOR A CE CHARACTERISTICS
Ripple Rejection
115
110
REJECTION (dB)
f = 150Hz
LT1021-7
120
LT1021-10
REJECTION (dB)
110
100
LT1021-7
INPUT/OUTPUT VOLTAGE (V)
105
100
LT1021-5
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
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
10
9
8
7
6
5
4
3
0
2
4
LT1021-10
V
OUT
+ 2V
1k
V
OUT
OUT
IN
GND
NOISE VOLTAGE (nV/√Hz)
LT1021-7
LT1021-5
6
8
TIME (µs)
10
Output Voltage Noise
16
14
12
RMS NOISE (µV)
C
OUT
= 0
FILTER = 1 POLE
f
LOW
= 0.1Hz
OUTPUT VOLTAGE (V)
OUTPUT CHANGE (mV)
10
8
LT1021-7
6
4
LT1021-5
2
0
10
100
1k
BANDWIDTH (Hz)
10k
LT1021 G07
LT1021-10
U W
35
40
LT1021 G01
Ripple Rejection
130
1.6
Minimum Input/Output Differential
LT1021-7, LT1021-10
T
J
= 125
°C
T
J
= –55
°C
T
J
= 25
°C
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
V
IN
= 15V
C
OUT
= 0
LT1021-10
90
LT1021-5
80
70
60
50
10
100
1k
FREQUENCY (Hz)
10k
LT1021 G02
0
2
4
6 8 10 12 14 16 18 20
OUTPUT CURRENT (mA)
1021 G03
Start-Up (Shunt Mode)
LT1021-7, LT1021-10
11
LT1021-10
10
9
8
7
6
5
12
14
0V
NC
Output Voltage Noise Spectrum
400
350
300
250
200
150
100
50
0
LT1021-10
LT1021-7
LT1021-5
LT1021-7
0
2
6
4
TIME (µs)
8
10
12
10
100
1k
FREQUENCY (Hz)
10k
LT1021 G06
LT1021 G04
LT1021 G05
Output Voltage Temperature Drift
LT1021-5
5.006
5.004
5.002
5.000
4.998
4.996
4.994
– 50 –25
Load Regulation LT1021-5
5
4
3
2
1
0
–1
–2
–3
–4
V
IN
= 8V
50
25
0
75
TEMPERATURE (°C)
100
125
–5
–10 – 8 – 6 – 4 – 2
SOURCING
0
2
4 6 8
SINKING
10
LT1021 G08
OUTPUT CURRENT (mA)
LT1021 G09
5
