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LT1021

Precision Reference

Typical Distribution of Temperature Drift

OUTPUT DRIFT (ppm/°C)

–5

UNITS (%)

– 0

1021 TA01

–3 –1 1 52–4 –2 0 4

DISTRIBUTION

OF THREE RUNS

ITY

Basic Positive and Negative Connections

LT1021

OUT

GND

LT1021

(7 AND 10 ONLY)

OUT

GND

OUT

–V

OUT

R1 =

OUT

– (V

–

)

LOAD

+ 1.5mA

–15V

–

)

1021 TA01

■

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

■

A/D and D/A Converters

■

Precision Regulators

■

Digital Voltmeters

■

Inertial Navigation Systems

■

Precision Scales

■

Portable Reference Standard

, LTC and LT are registered trademarks of Linear Technology Corporation.

ESCRIPTIO

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%.

Summary of content (17 pages)

PAGE 1
LT1021 Precision Reference U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ 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.
PAGE 2
LT1021 W W W AXI U U ABSOLUTE RATI GS (Note 1) 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 ..
PAGE 3
LT1021 ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are TA = 25°C. VIN = 10V, IOUT = 0, unless otherwise noted. PARAMETER CONDITIONS Output Voltage (Note 2) LT1021C-5 LT1021B-5/LT1021D-5 Output Voltage Temperature Coefficient (Note 3) TMIN ≤ TJ ≤ TMAX LT1021B-5 LT1021C-5/LT1021D-5 Line Regulation (Note 4) MIN LT1021-5 TYP MAX 4.9975 4.9500 5.000 5.000 5.0025 5.
PAGE 4
LT1021 ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are TA = 25°C. VIN = 15V, IOUT = 0, unless otherwise noted. PARAMETER CONDITIONS MIN LT1021-10 TYP MAX Output Voltage (Note 2) LT1021C-10 LT1021B-10/LT1021D-10 9.995 9.950 10.00 10.00 10.005 10.050 Output Voltage Temperature Coefficient (Note 3) TMIN ≤ TJ ≤ TMAX LT1021B-10 LT1021C-10/LT1021D-10 2 5 5 20 ppm/°C ppm/°C 1.
PAGE 5
LT1021 U W TYPICAL PERFOR A CE CHARACTERISTICS VIN = 15V COUT = 0 LT1021-7 120 REJECTION (dB) 105 LT1021-7 110 LT1021-10 100 LT1021-5 95 100 LT1021-10 90 LT1021-5 80 70 90 60 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 VIN = 0V TO 12V 6 LT1021-5 VOUT + 2V 0V 9 NC 8 7 1k VOUT OUT IN GND LT1021-7 6 4 2 4 6 8 TIME (µs) 10 12 0 14 2 6 4 TIME (µs) 8 150 LT1021-10 100 LT1021-7 50 LT1021-5 12 Load Regulation LT1021-5 5 LT1021-7 LT1021-10 4 LT1021-5 5.002 5.000 4.
PAGE 6
LT1021 U W TYPICAL PERFOR A CE CHARACTERISTICS Sink Mode* Current Limit LT1021-5 Quiescent Current LT1021-5 60 IOUT = 0 CURRENT INTO OUTPUT (mA) 1.6 INPUT CURRENT (mA) 1.4 1.2 TJ = – 55°C 1.0 TJ = 25°C 0.8 TJ = 125°C 0.6 0.4 Thermal Regulation LT1021-5 VIN = 8V VIN = 25V ∆POWER = 200mW 50 OUTPUT CHANGE (mV) 1.8 40 30 20 LOAD REGULATION 0 – 0.5 THERMAL REGULATION – 1.0 ILOAD = 10mA 10 0.
PAGE 7
LT1021 U W TYPICAL PERFOR A CE CHARACTERISTICS Shunt Mode Current Limit LT1021-7 Shunt Characteristics LT1021-7 60 0.8 TJ = – 55°C TJ = 25°C 0.6 0.4 TJ = 125°C 0.2 0 Thermal Regulation LT1021-7 VIN = 27V ∆POWER = 200mW INPUT PIN OPEN 50 OUTPUT CHANGE (mV) INPUT PIN OPEN 1.0 CURRENT INTO OUTPUT (mA) CURRENT INTO OUTPUT (mA) 1.2 40 30 20 LOAD REGULATION 0 – 0.5 THERMAL REGULATION* –1.0 –1.
PAGE 8
LT1021 U W TYPICAL PERFOR A CE CHARACTERISTICS Shunt Mode Current Limit LT1021-10 Shunt Characteristics LT1021-10 60 INPUT PIN OPEN CURRENT INTO OUTPUT (mA) CURRENT INTO OUTPUT (mA) 1.6 1.4 1.2 TJ = – 55°C 1.0 0.8 TJ = 25°C 0.6 0.4 TJ = 125°C Thermal Regulation LT1021-10 VIN = 30V ∆POWER = 200mW INPUT PIN OPEN 50 OUTPUT CHANGE (mV) 1.8 40 30 20 LOAD REGULATION 0 – 0.5 –1.0 THERMAL REGULATION* –1.5 ILOAD = 10mA 10 0.
PAGE 9
LT1021 U U W U APPLICATIONS INFORMATION 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.
PAGE 10
LT1021 U U W U APPLICATIONS INFORMATION minimized. In the current output circuit, R1 determines output current. It should have a TC commensurate with the LT1021 or track closely with the feedback resistor around the op amp. LT1021-7 IN OUT R2* 14k 1% GND R3 10k R1* 200Ω 1% VOUT 6.
PAGE 11
LT1021 U W U U APPLICATIONS INFORMATION The LT1021 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 between IC package leads (especially kovar lead TO-5) and printed circuit board materials and/or sockets.
PAGE 12
LT1021 U TYPICAL APPLICATIONS Boosted Output Current with No Current Limit Boosted Output Current with Current Limit V + ≥ (VOUT + 1.8V) Ultraprecise Current Source V + ≥ VOUT + 2.8V D1* LED R1 220Ω R1 220Ω LT1021-7 8.2Ω 15V 2N2905 IN 2N2905 IN OUT 17.4k 1% GND TRIM 100Ω IN LT1021 10V AT 100mA + 10V AT 100mA OUT 2µF SOLID TANT GND + 6.98k* 0.
PAGE 13
LT1021 U TYPICAL APPLICATIONS Negative Shunt Reference Driven by Current Source Strain Gauge Conditioner for 350Ω Bridge R1 357Ω 1/2W LT1021-10 15V IN OUT 28mA LT1021-10 GND 28.5mA OUT 5V 350Ω STRAIN GAUGE BRIDGE** GND + 6 3 R2 20k 2 R4 20k † LM301A – 1 100pF –10V (ILOAD ≤ 1mA) R3 2M 2 2.
PAGE 14
LT1021 U TYPICAL APPLICATIONS Ultralinear Platinum Temperature Sensor* LT1021-10 IN OUT R2* 5k 20V GND R10 182k 1% R14 5k R1** 253k R9 100k R11 6.65M 1% R8 10M R15 10k RF** 654k R12 1k R13 24.3k 20V R4 4.75k 1% R3** 5k RS† 100Ω AT 0°C 2 R5 200k 1% LT1001 3 R6 619k 1% R7 392k 1% –15V 7 – + 6 VOUT =100mV/°C – 50°C ≤ T ≤ 150°C 4 –15V † STANDARD INDUSTRIAL 100Ω PLATINUM 4-WIRE SENSOR, ROSEMOUNT 78S OR EQUIVALENT. α = 0.
PAGE 15
LT1021 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. H Package 8-Lead TO-5 Metal Can (0.200 PCD) (LTC DWG # 05-08-1320) 0.335 – 0.370 (8.509 – 9.398) DIA 0.305 – 0.335 (7.747 – 8.509) 0.040 (1.016) MAX 0.050 (1.270) MAX SEATING PLANE 0.165 – 0.185 (4.191 – 4.699) GAUGE PLANE 0.010 – 0.045* (0.254 – 1.143) REFERENCE PLANE 0.500 – 0.750 (12.700 – 19.050) 0.016 – 0.021** (0.406 – 0.533) 0.027 – 0.045 (0.686 – 1.143) 45°TYP PIN 1 0.028 – 0.034 (0.711 – 0.864) 0.
PAGE 16
LT1021 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.189 – 0.197* (4.801 – 5.004) 8 7 6 5 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) 1 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 2 3 4 0.053 – 0.069 (1.346 – 1.752) 0.004 – 0.010 (0.101 – 0.254) 0°– 8° TYP 0.016 – 0.050 0.406 – 1.270 0.014 – 0.019 (0.355 – 0.483) 0.050 (1.
PAGE 17
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