Analog Devices 1B51BN, 1B51AN Datasheet

Isolated mV/Thermocouple

a

FEATURES
Functionally Complete Precision Conditioner
High Accuracy

Low Input Offset Tempco: 60.1 mV/8C
Low Nonlinearity: 60.025%

High CMR: 160 dB (60 Hz, G = 1000 V/V)
High CMV Isolation: 1500 V rms Continuous
240 V rms Input Protection
Small Package: 1.0" 3 2.1" 3 0.35" DIP
Isolated Power
Low-Pass Filter (f
Pin Compatible with 1B41 Isolated RTD Conditioner

APPLICATIONS
Multichannel Thermocouple Temperature
Measurement
Low Level Data Acquisition Systems
Industrial Measurement & Control Systems

GENERAL DESCRIPTION

The 1B51 is a precision, mV/thermocouple signal conditioner
that incorporates a circuit design utilizing transformer based iso­lation and automated surface mount manufacturing technology.
It provides an unbeatable combination of versatility and perfor­mance in a compact plastic package. Designed for measurement
and control applications, it is specially suited for harsh environ­ments with extremely high common-mode interference. Unlike
costlier solutions that require separate dc/dc converters, each
1B51 generates its own input side power, providing true, low
cost channel-to-channel isolation.

Functionally, the signal conditioner consists of three basic sec­tions: chopper stabilized amplifier, isolation and output filter.
The chopper amplifier features a highly stable offset tempco of
±0.1 µV/°C and resistor programmable gains from 2 to 1000.
Wide range zero suppression can be implemented at this stage.

The isolation section has complete input to output galvanic iso­lation of 1500 V rms continuous using transformer coupling
techniques. Isolated power of 2 mA at ±6.2 V is provided for
ancillary circuits such as zero suppression and open-input detec­tion. Filtering at 3 Hz is implemented by a passive antialiasing
filter at the front end and a two-pole active filter at the output.

= 3 Hz)

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Signal Conditioner

1B51

FUNCTIONAL BLOCK DIAGRAM

Overall NMR is 60 dB and CMR is 160 dB min @ 60 Hz,
G = 1000.

The 1B51 is specified over –25°C to +85°C and operates over
the industrial (–40°C to +85°C) temperature range.

DESIGN FEATURES AND USER BENEFITS

High Noise Rejection: The combination of a chopper stabi-

lized front end with a low-pass filter provides high system accu­racy in harsh industrial environments as well as excellent
rejection of 50 Hz/60 Hz noise.

Input Protection: The input is internally protected against
continuous application of 240 V rms.

Low Cost: The 1B51 offers a very low cost per channel for
high performance, isolated, low level signal conditioners.

Wide Range Zero Suppression: This input referred function
is a convenient way to null large input offsets.

Low-Pass Filter: The three pole active filter (f
reduces 60 Hz noise and aliasing errors.

Small Size: The 1B51 package size (1.0" × 2.1" × 0.35") and
functional completeness make it an excellent choice in systems
with limited board space and clearance.

= 3 Hz)

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REV. A

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reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] Fax: [phone]

1B51–SPECIFICA TIONS

Model 1B51AN 1B51BN

GAIN

Gain Equation
Gain Error 1% max *

Gain Temperature Coefficient
Gain Nonlinearity ± 0.035% (± 0.05% max) ± 0.025% (±0.04% max)

OFFSET VOLTAGES

Input Offset Voltage

Initial, @ +25°C (Adjustable to Zero) 25 µV (100 µV max) *
vs. Temperature ±0.1 µV/°C (±0.5 µV/°C max) *
vs. Time, Noncumulative ±1 µV/month max *

Output Offset Voltage

Initial –50 mV –25 mV
vs. Temperature –175 µV/°C –50 µV/°C

INPUT OFFSET CURRENT

Initial 0.6 nA (2.5 nA max) *

vs. Temperature ±2.5 pA/°C (12.5 pA/°C max) *

INPUT BIAS CURRENT

Initial @ +25°C 10 nA *

vs. Temperature 10 pA/°C*

INPUT IMPEDANCE

Power On 50 MΩ *
Power Off 40 kΩ min *

INPUT VOLTAGE RANGE

Linear Differential Input ±10 mV to ± 5 V *
Max CMV, Input to Output

AC, 60 Hz, Continuous 1500 V rms *

Continuous, DC ±2000 V *
CMR @ 6 0 Hz, 1 kΩ Source Imbalance, G = 1000 160 dB min *
NMR @ 60 Hz 60 dB min *
Transient Protection IEEE-STD 472 (SWC) *

INPUT NOISE

Voltage, 0.1 Hz to 10 Hz, 1 kΩ Source Imbalance 1 µV p-p *

RATED OUTPUT

Voltage, 2 kΩ Load, min ±10 V *
Current ±5 mA *
Output Noise, DC to 100 kHz 1 mV p-p *
Impedance, DC 0.1 Ω *

FREQUENCY RESPONSE

Bandwidth, –3 dB dc to 3 Hz *

ISOLATED POWER

Voltage, No Load ±6.2 V ±5% *
Current 2 mA *
Regulation, No Load to Full Load 7.5% *
Ripple 250 mV p-p *

POWER SUPPLY

Voltage, Rated Performance ±15 V dc *
Voltage, Operating ± 13.5 V to ±18 V *
Current, Quiescent +12 mA @ +15 V, –4 mA @ –15 V *
PSRR 0.1%/V *

ENVIRONMENTAL

Temperature Range

Rated Performance –25° C to +85°C*

Operating –40°C to +85°C*

Storage –40°C to +85°C*
Relative Humidity 0 to 95%, @ +60°C*

CASE SIZE 1.00" × 2.10" × 0.35" *

NOTES

•Specifications same as 1B51AN.

1

See graph in text.

Specifications subject to change without notice.

1

(typical at +258C and VS = 615 V unless otherwise noted)

R





G = 1+

50 ppm/°C*

(25.4 × 53.3 × 8.9) mm

FB




× 2



R

G



*

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

PIN DESIGNATIONS

Pin Designation

11HI
12 PROT HI
14 ICOM
15LO

16 +15 V
17 –15 V
22 V

O

23 GND
34 –V
35 +V

ISO

ISO

37 GAIN
38 FB

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