LTZ1000CH

LTZ1000 LINER

Document overview

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Technical content

FEATURES

APPLICATIONS

DESCRIPTION

The L TZ1000 and L TZ1000A are ultra-stable temperature controllable references. They are designed to provide 7V outputs with temperature drifts of 0.05ppm/°C, about 1.2μV P-P of noise and long-term stability of 2μV/√kHr . Included on the chip is a subsurface zener reference, a heater resistor for temperature stabilization, and a tem- perature sensing transistor . External circuitry is used to set operating currents and to temperature stabilize the reference. This allows maximum fl exibility and best long- term stability and noise. The L TZ1000 and L TZ1000A references can provide su- perior 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 L TZ1000A uses a proprietary die attach method to provide signifi cantly higher thermal resistance than the L TZ1000. Low Noise Reference n 1.2μV P-P Noise n 2μV/√kHr Long-Term Stability n Very Low Hysteresis n 0.05ppm/°C Drift n Temperature Stabilized n 400°C/W Thermal Resistance for L TZ1000A Reduces Insulation Requirements n Specifi ed for –55°C to 125°C Temperature Range n Offered in TO-99 package n Voltmeters n Calibrators n Standard Cells n Scales n Low Noise RF Oscillators Long-Term Stability L, L T , L TC and L TM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. L TZ1000 OUTPUT 1N4148 LT®1006 VIN ≥ 10V 30k 3 7 0.02μF120Ω

1000 TA01

(ppm) LONG-TERM STABILITY OF A TYPICAL DEVICE FROM TIME = 0 WITH NO PRECONDITIONING OR AGING

1000 TA01b

ELECTRICAL CHARACTERISTICS

A ≤ 125°C (Note 1) 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. 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 ≤ I Z < 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 μV P-P Heater Resistance IL ≤ 100μA 200 300 420 Ω Heater Breakdown Voltage 35 V T ransistor Q1 Breakdown IC = 10μA, LVCEO 15 20 V T ransistor Q2 Breakdown IC = 10μA, LVCEO 35 50 V Q1, Q2 Current Gain IC = 100μA 80 200 450 Thermal Resistance L TZ1000 Time = 5 Minutes L TZ1000A Time = 5 Minutes 400 °C/W °C/W Long-Term Stability T = 65°C 2 μV√kHr (Note 2) Note 2: All testing is done at 25°C. Pulse testing is used for L TZ1000A to minimize temperature rise during testing. L TZ1000 and L TZ1000A devices are QA tested at –55°C and 125°C. PIN CONFIGURATION BOTTOM VIEW H8 PACKAGE TO-5 METAL CAN TJMAX = 80°C, θJA = 400°C/W ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE L TZ1000ACH#PBF L TZ1000ACH#TRPBF 8-Lead TO-5 Metal Can (.200 Inch PCD) –55°C to 125°C L TZ1000CH#PBF L TZ1000CH#TRPBF 8-Lead TO-5 Metal Can (.200 Inch PCD) –55°C to 125°C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE L TZ1000ACH L TZ1000ACH#TR 8-Lead TO-5 Metal Can (.200 Inch PCD) –55°C to 125°C L TZ1000CH L TZ1000CH#TR 8-Lead TO-5 Metal Can (.200 Inch PCD) –55°C to 125°C Consult L TC Marketing for parts specifi ed with wider operating temperature ranges. For more information on lead free part marking, go to: http://www.linear .com/leadfree/ For more information on tape and reel specifi cations, go to: http://www.linear .com/tapeandreel/

TYPICAL PERFORMANCE CHARACTERISTICS Zener Voltage vs Current Zener Voltage Noise Spectrum Zener Noise Die Temperature Rise vs Heater Power Die Temperature vs Time Die Temperature Rise vs Time 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 T ransistor Collector . Pin 6: Temperature Sensing T ransistor Base. If the base emitter junction is zenered (about 7V) the transistor will suffer permanent beta degradation. Pin 7: Emitter of Sensing and Compensating T ransistors. Pin 8: Collector of Sensing T ransistor . ZENER CURRENT (mA) ZENER VOL TAGE CHANGE (mV) 100 4.0 ZENER ALONE ZENER WITH KELVIN SENSED Q1

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FREQUENCY (Hz) 0.1 200ZENER VOL TAGE NOISE (nV/√Hz) 250 300 350 400 1 10 100 150 100 450 500 ZENER CURRENT = 0.5mA ZENER CURRENT = 4mA

1000 G02

TIME (SECONDS) ZENER VOL TAGE NOISE (2μV/D) 10 20 30 40 50 60 IZ = 4mA IZ = 0.5mA

1000 G03

DIE TEMPERATURE ABOVE AMBIENT (°C) HEATER POWER (W) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 10545 65 85 125 9535 55 75 115 L TZ1000 L TZ1000A

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TIME (SECONDS) DIE TEMPERATURE RISE (°C) 125 100 0.1 10 100 1000 HEATER POWER = 0.1W HEATER POWER = 0.2W HEATER POWER = 0.3W L TZ1000A

1000 G05

TIME (SECONDS) DIE TEMPERATURE RISE (°C) 125 100 0.1 10 100 1000 HEATER POWER = 0.3W HEATER POWER = 0.7W L TZ1000

1000 G06

HEATER POWER = 0.5W

L TZ1000 and L TZ1000A 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 infl uences 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 coef- fi cients, can generate thermocouple effects. Some types of resistors can generate hundreds of microvolts of thermo- couple 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 fi lm resistors, can have low thermocouple voltage. Ordinary breadboarding techniques are not good enough to give stable output voltage with the L TZ1000 family devices. For breadboarding, it is suggested that a small printed circuit board be made up using the reference, the amplifi er and wire wound resistors. Care must be taken to ensure that heater current does not fl ow 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. BLOCK DIAGRAM Q2 Q1 624 7 *SUBSTRATE DEVICES–DO NOT FORWARD BIAS

1000 TA07

Negative Voltage Reference L T1013 1N4148 ZENER – FORCE ZENER – SENSE ZENER + SENSE 0.022μF 0.1μF 0.1μF V– ≥ 10V 400k* R4/R5 RATIO 100ppm = $R(Ω) 0.012Ω $R = 0.01% Z 1ppm 0.3ppm 0.2ppm 1ppm *PROVIDE TEMPERATURE COMPENSATION, DELETE FOR L TZ1000A BOTH A1 AND A2 CONTRIBUTE LESS THAN 2μV OF OUTPUT DRIFT OVER A 50°C RANGE APPROXIMATE CHANGE IN REFERENCE VOL TAGE FOR A 100ppm CHANGE IN RESISTOR VALUES: 2N3904 10k V + 15V GND L T1013 8 5 70k 13k 70k 120

1000 TA02

Setting Control Temperature The emitter-base voltage of the control transistor sets the stabilization temperature for the L TZ1000. 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. Because higher temperatures accelerate aging and decrease long-term stability, the lowest temperature consistent with the operating environment should be used. The L TZ1000A should be set about 10°C higher than the L TZ1000. This is because normal operating power dissipation in the L TZ1000A 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. For applications not requiring the extreme precision or the low noise of the L TZ1000, Linear Technology makes a broad line of voltage references. Devices like the L T1021 can provide drifts as low as 2ppm/°C and devices such as the LM399A can provide drifts of 1ppm/°C. Only applica- tions requiring the very low noise or low drift with time of the L TZ1000 should use this device. See Application Notes AN-82 and AN-86 for further information. Consult the Linear Technology Applications department for ad- ditional help. APPLICATIONS INFORMATION

Adjusting Temperature Coeffi cient in Unstabilized Applications TYPICAL APPLICATIONS 120Ω L T1006 70k 15V 1N4148 VOUT+ 0.022μF 200Ω* HEATER 1N4148

1 MIN

• PULSE HEATER ON AND OFF TO HEAT AND COOL THE REFERENCE. ADJUST R1 FOR MINIMUM VOL TAGE CHANGE THROUGH A TEMPERATURE CYCLE. THE –2mV/°C TEMPCO OF THE V BE CANCELS THE +2mV/°C TEMPCO OF THE ZENER.

1000 TA05

Averaging Reference Voltage for Lower Noise and Better Stability Improving Supply Rejection 1.6k VIN 15V 0.01% OUTPUT 1.6k 30Ω* 30Ω* 150Ω 150Ω *R = kT q IC

1000 TA03

1.5k 150Ω SUPPL Y REJECTION AT VOUT2 = 3mV/V SUPPL Y REJECTION AT VOUT1 = 20mV/V VOUT2 VOUT1 50Ω

1000 TA04

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 representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. 7V Positive Reference Circuit 2N3904 1N4148 1N4148 L T1013 L T1013 0.1μF 0.002μF 0.1μF 400k* 10k 13k 120Ω 70k 70k ZENER – SENSE ZENER + SENSE GROUND ZENER – FORCE HEATER RETURN (TIED TO GROUND) V+ 15V *PROVIDES TC COMPENSATION, DELETE FOR L TZ1000A APPROXIMATE CHANGE IN REFERENCE VOL TAGE FOR A 100ppm (0.01%) CHANGE IN RESISTOR VALUES: R4/R5 RATIO $R(Ω) 0.012Ω $R = 0.01% Z 1ppm 0.3ppm 0.2ppm 1ppm BOTH A1 AND A2 CONTRIBUTE LESS THAN 2μV OF OUTPUT DRIFT OVER A 50°C RANGE

1000 TA06

Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 1987 LT 1207 REV C • PRINTED IN USA RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LM399 7V Precision Shunt Reference 0.2% Accuracy, 0.5ppm/°C Drift, 20μV RMS Noise L T1021 5V , 7V and 10V Precision Reference Available in T0-5, –55°C to 125°C, Series or Shunt Operation L T1236 5V and 10V Low Drift Precision Reference 0.05% Accuracy, 5ppm/°C Drift, Series or Shunt Operation L T1389 1.25V , 2.5V , 4V and 5V Nanopower Shunt Reference 800nA, 0.05% Accuracy, 10ppm/°C Drift L T1634 1.25V and 2.5V Micropower Shunt Reference 0.05%, 10ppm/°C, 10μA Current PACKAGE DESCRIPTION H Package 8-Lead TO-5 Metal Can (.200 Inch PCD) (Reference LTC DWG # 05-08-1320) .050 (1.270) MAX .016 – .021** (0.406 – 0.533) .010 – .045* (0.254 – 1.143) SEATING PLANE .040 (1.016) MAX .165 – .185 (4.191 – 4.699) GAUGE PLANE REFERENCE PLANE .500 – .750 (12.700 – 19.050) .305 – .335 (7.747 – 8.509) .335 – .370 (8.509 – 9.398) DIA .200 (5.080) TYP .027 – .045 (0.686 – 1.143) .028 – .034 (0.711 – 0.864) .110 – .160 (2.794 – 4.064) INSULATING STANDOFF 45° H8(TO-5) 0.200 PCD 0204 LEAD DIAMETER IS UNCONTROLLED BETWEEN THE REFERENCE PLANE AND THE SEATING PLANE FOR SOLDER DIP LEAD FINISH, LEAD DIAMETER IS .016 – .024 (0.406 – 0.610) PIN 1