LINER LTZ1000_12

LTZ1000/LTZ1000A
Ultra Precision Reference
Features
Description
1.2µVP-P Noise
2µV/√kHr Long-Term Stability
n Very Low Hysteresis
n0.05ppm/°C Drift
n Temperature Stabilized
n400°C/W Thermal Resistance for LTZ1000A Reduces
Insulation Requirements
n Specified for –55°C to 125°C Temperature Range
n Offered in TO-99 package
The LTZ1000 and LTZ1000A are ultra-stable temperature
controllable references. They are designed to provide 7V
outputs with temperature drifts of 0.05ppm/°C, about
1.2µVP-P of noise and long-term stability of 2µV/√kHr.
n
n
Applications
n
n
n
n
n
Included on the chip is a subsurface zener reference, a
heater resistor for temperature stabilization, and a temperature sensing transistor. External circuitry is used to
set operating currents and to temperature stabilize the
reference. This allows maximum flexibility and best longterm stability and noise.
The LTZ1000 and LTZ1000A references can provide superior performance to older devices such as the LM199,
provided that the user implements the heater control and
properly manages the thermal layout. To simplify thermal
insulation, the LTZ1000A uses a proprietary die attach
method to provide significantly higher thermal resistance
than the LTZ1000.
Voltmeters
Calibrators
Standard Cells
Scales
Low Noise RF Oscillators
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Typical Application
Low Noise Reference
LTZ1000
Long-Term Stability
2
VIN ≥ 10V
OUTPUT
30k
+
LT®1006
2
120Ω
–
1N4148
7
6
(ppm)
3
0
4
0.02µF
–2
1000 TA01
0
10
20
30
DAYS
LONG-TERM STABILITY OF A TYPICAL DEVICE FROM TIME = 0
WITH NO PRECONDITIONING OR AGING
1000 TA01b
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LTZ1000/LTZ1000A
Absolute Maximum Ratings
(Note 1)
Pin Configuration
Heater to Substrate....................................................35V
Collector Emitter Breakdown Q1................................15V
Collector Emitter Breakdown Q2................................35V
Emitter Base Reverse Bias...........................................2V
Operating Temperature Range..........–55°C ≤ TA ≤ 125°C
Storage Temperature Range.............–65°C ≤ TA ≤ 150°C
Substrate Forward Bias............................................. 0.1V
BOTTOM VIEW
8
7
1
Q2
6
2
Q1
7V
5
3
4
H8 PACKAGE
TO-5 METAL CAN
TJMAX = 150°C,
LTZ1000CH: θJA = 80°C/W
LTZ1000ACH: θJA = 400°C/W
Order Information
LEAD FREE FINISH
PART MARKING
PACKAGE DESCRIPTION
SPECIFIED TEMPERATURE RANGE
LTZ1000ACH#PBF
LTZ1000ACH
8-Lead TO-5 Metal Can (.200 Inch PCD)
–55°C to 125°C
LTZ1000CH#PBF
LTZ1000CH
8-Lead TO-5 Metal Can (.200 Inch PCD)
–55°C to 125°C
LEAD BASED FINISH
PART MARKING
PACKAGE DESCRIPTION
SPECIFIED TEMPERATURE RANGE
LTZ1000ACH
LTZ1000ACH
8-Lead TO-5 Metal Can (.200 Inch PCD)
–55°C to 125°C
LTZ1000CH
LTZ1000CH
8-Lead TO-5 Metal Can (.200 Inch PCD)
–55°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/
Electrical
Characteristics
(Note
2)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Zener Voltage
lZ = 5mA, (VZ + VBEQ1) IQ1 = 100µA
lZ = 1mA, (VZ + VBEQ1) IQ1 = 100µA
7.0
6.9
7.2
7.15
7.5
7.45
V
V
Zener Change with Current
1mA ≤ IZ < 5mA
80
240
mV
Zener Leakage Current
VZ = 5V
20
200
µA
Zener Noise
lZ = 5mA, 0.1Hz < f < 10Hz
1Q1 = 100µA
1.2
2
Heater Resistance
IL ≤ 100µA
300
420
200
Heater Breakdown Voltage
µVP-P
Ω
35
V
Transistor Q1 Breakdown
IC = 10µA, LVCEO
15
20
V
Transistor Q2 Breakdown
IC = 10µA, LVCEO
35
50
V
Q1, Q2 Current Gain
IC = 100µA
80
200
Thermal Resistance
LTZ1000
LTZ1000A
Long-Term Stability
T = 65°C
Time = 5 Minutes
Time = 5 Minutes
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
80
400
2
450
°C/W
°C/W
µV√kHr
Note 2: All testing is done at 25°C. Pulse testing is used for LTZ1000A to
minimize temperature rise during testing. LTZ1000 and LTZ1000A devices
are QA tested at –55°C and 125°C.
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LTZ1000/LTZ1000A
Typical Performance Characteristics
Zener Voltage Noise Spectrum
90
450
80
ZENER ALONE
70
60
50
40
30
20
ZENER WITH KELVIN
SENSED Q1
10
0
0
IZ = 4mA
400
350
300
250
ZENER CURRENT = 0.5mA
200
150
100
ZENER CURRENT = 4mA
50
0
0.1
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
ZENER CURRENT (mA)
Zener Noise
1
10
FREQUENCY (Hz)
1000 G01
ZENER VOLTAGE NOISE (2µV/D)
500
ZENER VOLTAGE NOISE (nV/√Hz)
ZENER VOLTAGE CHANGE (mV)
Zener Voltage vs Current
100
IZ = 0.5mA
100
0
20
30
40
TIME (SECONDS)
10
1000 G02
Die Temperature Rise
vs Heater Power
125
60
1000 G03
Die Temperature vs Time
0.8
50
Die Temperature Rise vs Time
125
LTZ1000A
LTZ1000
0.6
0.5
LTZ1000
0.4
0.3
0.2
LTZ1000A
100
HEATER POWER = 0.3W
75
HEATER POWER = 0.2W
50
25
HEATER POWER = 0.1W
0.1
0
DIE TEMPERATURE RISE (°C)
DIE TEMPERATURE RISE (°C)
HEATER POWER (W)
0.7
100
75
50
HEATER POWER = 0.7W
HEATER POWER = 0.5W
25
HEATER POWER = 0.3W
25 35 45 55 65 75 85 95 105 115 125
DIE TEMPERATURE ABOVE AMBIENT (°C)
0
0.1
1
10
100
TIME (SECONDS)
1000 G04
1000
0
0.1
1
10
100
TIME (SECONDS)
1000 G05
1000
1000 G06
Pin Functions
Pin 1: Heater Positive. Must have a higher positive value
than Pin 2 and Pin 4.
Pin 2: Heater Negative. Must have a higher positive value
than Pin 4. Must have equal or lower potential than Pin 1.
Pin 3: Zener Positive. Must have a higher positive value
than Pin 4.
Pin 4: Substrate and Zener Negative. Must have a higher
positive value than Pin 7. If Q1 is zenered (about 7V) a
permanent degradation in beta will result.
Pin 5: Temperature Compensating Transistor Collector.
Pin 6: Temperature Sensing Transistor Base. If the base
emitter junction is zenered (about 7V) the transistor will
suffer permanent beta degradation.
Pin 7: Emitter of Sensing and Compensating Transistors.
Pin 8: Collector of Sensing Transistor.
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LTZ1000/LTZ1000A
Block Diagram
1
8
3
5
*
*
Q2
Q1
*
2
6
*SUBSTRATE DEVICES–DO NOT FORWARD BIAS
4
7
1000 TA07
Applications Information
LTZ1000 and LTZ1000A are capable of providing ultimate
voltage reference performance. Temperature drifts of better
than 0.03ppm/°C and long-term stability on the order of
1µV per month can be achieved. Noise of about 0.15ppm
can also be obtained. This performance is at the expense
of circuit complexity, since external influences can easily
cause output voltage shifts of more than 1ppm.
Thermocouple effects are one of the worst problems and
can give apparent drifts of many ppm/°C as well as cause
low frequency noise. The kovar input leads of the TO-5
package form thermocouples when connected to copper
PC boards. These thermocouples generate outputs of
35µV/°C. It is mandatory to keep the zener and transistor
leads at the same temperature, otherwise 1ppm to 5ppm
shifts in the output voltage can easily be expected from
these thermocouples.
Air currents blowing across the leads can also cause small
temperature variations, especially since the package is
heated. This will look like 1ppm to 5ppm of low frequency
noise occurring over a several minute period. For best
results, the device should be located in an enclosed area
and well shielded from air currents.
Certainly, any temperature gradient externally generated,
say from a power supply, should not appear across the
critical circuitry. The leads to the transistor and zener
should be connected to equal size PC traces to equalize
the heat loss and maintain them at similar temperatures.
The bottom portion of the PC board should be shielded
against air currents as well.
Resistors, as well as having resistance temperature coefficients, can generate thermocouple effects. Some types of
resistors can generate hundreds of microvolts of thermocouple voltage. These thermocouple effects in the resistor
can also interfere with the output voltage. Wire wound
resistors usually have the lowest thermocouple voltage,
while tin oxide type resistors have very high thermocouple
voltage. Film resistors, especially Vishay precision film
resistors, can have low thermocouple voltage.
Ordinary breadboarding techniques are not good enough
to give stable output voltage with the LTZ1000 family
devices. For breadboarding, it is suggested that a small
printed circuit board be made up using the reference, the
amplifier and wire wound resistors. Care must be taken to
ensure that heater current does not flow through the same
ground lead as the negative side of the reference (emitter
of Q1). Current changes in the heater could add to, or
subtract from, the reference voltage causing errors with
temperature. Single point grounding using low resistance
wiring is suggested.
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LTZ1000/LTZ1000A
APPLICATIONS INFORMATION
is because normal operating power dissipation in the
LTZ1000A causes a temperature rise of about 10°C. Of
course both types of devices should be insulated from
ambient. Several minutes of warm-up is usual.
Setting Control Temperature
The emitter-base voltage of the control transistor sets the
stabilization temperature for the LTZ1000. With the values
given in the applications, temperature is normally 60°C.
This provides 15°C of margin above a maximum ambient
of 45°C, for example. Production variations in emitter-base
voltage will typically cause about ±10°C variation. Since
the emitter-base voltage changes about 2mV/°C and is
very predictable, other temperatures are easily set.
For applications not requiring the extreme precision or
the low noise of the LTZ1000, Linear Technology makes a
broad line of voltage references. Devices like the LT1021
can provide drifts as low as 2ppm/°C and devices such as
the LM399A can provide drifts of 1ppm/°C. Only applications requiring the very low noise or low drift with time of
the LTZ1000 should use this device. See Application Notes
AN-82 and AN-86 for further information. Consult the Linear
Technology Applications department for additional help.
Because higher temperatures accelerate aging and decrease
long-term stability, the lowest temperature consistent with
the operating environment should be used. The LTZ1000A
should be set about 10°C higher than the LTZ1000. This
Typical Applications
Negative Voltage Reference
ZENER + SENSE
V+ 15V
GND
0.1µF
1
2N3904
1k
7
+
5
–
6
LT1013
R4
13k
8
R3
70k
5
3
10k
4
1M
7
2
1N4148
R2
70k
0.1µF
400k*
2
3
R5
1k
R1
120
8
–
LT1013
+
4
1
1N4148
0.022µF
ZENER – FORCE
ZENER – SENSE
*PROVIDES TEMPERATURE COMPENSATION, DELETE FOR LTZ1000A
APPROXIMATE CHANGE IN REFERENCE VOLTAGE FOR A 100ppm CHANGE IN RESISTOR VALUES:
R1
R2
R3
R4/R5 RATIO
100ppm = ∆R(Ω)
0.012Ω
7Ω
7Ω
∆R = 0.01%
V– ≥ 10V
∆VZ
1ppm
0.3ppm
0.2ppm
1ppm
BOTH A1 AND A2 CONTRIBUTE LESS THAN 2µV OF OUTPUT DRIFT OVER A 50°C RANGE
1000 TA02
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LTZ1000/LTZ1000A
typical APPLICATIONS
Averaging Reference Voltage for Lower Noise and Better Stability
Improving Supply Rejection
VIN 15V
0.01%
VIN
15V
1.6k
1.6k
30Ω*
30Ω*
1.5k
VOUT1
SUPPLY REJECTION
AT VOUT1 = 20mV/V
VOUT2
SUPPLY REJECTION AT
VOUT2 = 3mV/V
50Ω
150Ω
OUTPUT
IC
150Ω
1000 TA04
150Ω
1000 TA03
*R = kT
q IC
Adjusting Temperature Coefficient in Unstabilized Applications
15V
1 MIN
VOUT+
R1
200Ω*
70k
3
3
5
2
4
1N4148
+
LT1006
–
7
120Ω
ON
*
OFF
1
1 MIN
6
HEATER
4
2
0.022µF
1N4148
* PULSE HEATER ON AND OFF TO HEAT AND COOL THE REFERENCE. ADJUST
R1 FOR MINIMUM VOLTAGE CHANGE THROUGH A TEMPERATURE CYCLE.
THE –2mV/°C TEMPCO OF THE VBE CANCELS THE +2mV/°C TEMPCO OF THE ZENER.
1000 TA05
7V Positive Reference Circuit
ZENER + SENSE
V+ 15V
1k
2N3904
7
+
5
–
6
A1
LT1013
R4
13k
10k
R3 3
70k
R2
70k
8
5
3
2
+
A2
LT1013
–
1N4148
8
1
4
7
4
1M
0.1µF
1
ZENER – SENSE
400k*
0.1µF
R5
1k
R1
120Ω
1N4148
2
0.002µF
GROUND
ZENER – FORCE
HEATER RETURN
(TIED TO GROUND)
*PROVIDES TC COMPENSATION, DELETE FOR LTZ1000A
APPROXIMATE CHANGE IN REFERENCE VOLTAGE FOR A 100ppm (0.01%) CHANGE IN RESISTOR VALUES:
R1
R2
R3
R4/R5 RATIO
∆R(Ω)
0.012Ω
7Ω
7Ω
∆R = 0.01%
∆VZ
1ppm
0.3ppm
0.2ppm
1ppm
BOTH A1 AND A2 CONTRIBUTE LESS THAN 2µV OF OUTPUT DRIFT OVER A 50°C RANGE
1000 TA06
1000afd
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LTZ1000/LTZ1000A
Revision History
(Revision history begins at Rev D)
REV
DATE
DESCRIPTION
D
4/12
Corrected thermal information on H8 package drawing
PAGE NUMBER
2
Corrected Order Information table
2
Updated Block Diagram to show substrate diode
4
Added 1N4148 label to diode in application circuit
5
Added LTC6655 to Related Parts table
8
1000afd
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.
7
LTZ1000/LTZ1000A
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
H Package
8-Lead TO-5 Metal Can (.200 Inch PCD)
(Reference LTC DWG # 05-08-1320)
.040
(1.016)
MAX
.335 – .370
(8.509 – 9.398)
DIA
.305 – .335
(7.747 – 8.509)
.050
(1.270)
MAX
SEATING
PLANE
.165 – .185
(4.191 – 4.699)
GAUGE
PLANE
.010 – .045*
(0.254 – 1.143)
REFERENCE
PLANE
.500 – .750
(12.700 – 19.050)
.016 – .021**
(0.406 – 0.533)
.027 – .045
(0.686 – 1.143)
45°
.028 – .034
(0.711 – 0.864)
PIN 1
.200
(5.080)
TYP
.110 – .160
(2.794 – 4.064)
INSULATING
STANDOFF
*LEAD DIAMETER IS UNCONTROLLED BETWEEN THE REFERENCE PLANE
AND THE SEATING PLANE
.016 – .024
**FOR SOLDER DIP LEAD FINISH, LEAD DIAMETER IS
(0.406 – 0.610) H8(TO-5) 0.200 PCD 0204
Related Parts
PART NUMBER
DESCRIPTION
COMMENTS
LM399
7V Precision Shunt Reference
0.2% Accuracy, 0.5ppm/°C Drift, 20µVRMS Noise
LT1021
5V, 7V and 10V Precision Reference
Available in T0-5, –55°C to 125°C, Series or Shunt Operation
LT1236
5V and 10V Low Drift Precision Reference
0.05% Accuracy, 5ppm/°C Drift, Series or Shunt Operation
LT1389
1.25V, 2.5V, 4V and 5V Nanopower Shunt Reference
800nA, 0.05% Accuracy, 10ppm/°C Drift
LT1634
1.25V and 2.5V Micropower Shunt Reference
0.05%, 10ppm/°C, 10µA Current
LTC6655
Precision Low Noise Reference Family
2ppm/°C, Maximum Drift, 650nVP-P Noise (0.1Hz to 10Hz)
1000afd
8
Linear Technology Corporation
LT 0412 REV D • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
 LINEAR TECHNOLOGY CORPORATION 1987