Analog Devices 1B22 Datasheet

Programmable, Isolated

a

FEATURES
Internal Isolated Loop Supply Drives 1000 ⍀ Load
Pin Programmable Inputs: 0 V to +5 V or 0 V to +10 V
Pin Programmable Outputs: 4 to 20 mA or 0 to 20 mA
High CMV Isolation: 1500 V RMS
Normal-Mode Output Protection: 240 V RMS
High Accuracy

Low Offset Tempco: ⴞ300 nA/ⴗC
Low Gain Tempco: ⴞ50 ppm/ⴗC
Low Nonlinearity: ⴞ0.02%

High CMR: 90 dB min
Small Package: 1.0" ⴛ 2.10" ⴛ 0.35"
Meets IEEE STD 472: CMV Transient Protection (SWC)

APPLICATIONS
Multichannel Process Control
D/A Converter—Current Loop Interface
Analog Transmitters and Controllers
Remote Data Acquisition Systems

GENERAL DESCRIPTION

The 1B22 is an isolated voltage-to-current converter that
incorporates transformer isolation to achieve high performance
and automated surface mount manufacturing for low cost
and increased reliability. Designed for industrial applications,
it is especially suited for harsh environments with extremely
high common-mode interference. With programmable inputs
and outputs, the 1B22 provides an unbeatable combination of
versatility and performance in a compact plastic package.

Functionally, the V/I converter consists of four basic sections:
input conditioning, modulator/demodulator, isolated loop
supply and current source (Figure 1). The 1B22 is pin program­mable for 0 V to +5 V or 0 V to +10 V inputs and 0 to 20 mA
or 4 to 20 mA outputs using an internal resistor network. It can
also be set by an external resistor to accept 0 V to +1 V to 0 V
to +10 V inputs. Transformer coupling provides 1500 V rms
galvanic isolation between the inputs and the current loop.
Nonlinearity is an excellent ±0.05% max.

Loop power is generated internally through a dc/dc converter
and is also isolated from the input side (1500 V rms). Loop
compliance voltage is dependent on the voltage supplied to the
1B22, and with V
load.

The 1B22 is fully specified over –25°C to +85°C and operates
over the industrial (–40°C to +85°C) temperature range.

= 28 V, it is sufficient to drive a 1000 Ω

LOOP

Voltage-to-Current Converter

1B22

FUNCTIONAL BLOCK DIAGRAM

IN1

IN2

4mA

OFFSET

S. NODE

SYNC

+15V

–15V

A. COM

RESISTOR
NETWORK

REF

OSCILLATOR

V

P. COM

SIGNAL

ISOLATION

POWER

ISOLATION

LOOP

DESIGN FEATURES AND USER BENEFITS

Isolated Loop Power: Internal loop supply completely

isolates the loop from the input terminals (1500 V rms) and
provides the capability to drive 0 Ω to 1000 Ω loads. This elimi­nates the need for an external dc/dc converter.

Ease of Use: The 1B22 offers complete isolated voltage-to­current conversion with minimum external parts required to get
a conditioned current signal. No external buffers or drivers are
required.

High CMV Isolation: The 1B22 features high input to output
galvanic isolation to eliminate ground loops and offer protection
against damage from transients and fault voltages. The isolation
barrier will withstand continuous CMV of 1500 V rms and meets
the IEEE Standard for Common-Mode Voltage Transient Pro­tection (STD 472-SWC).

Small Size: The 1B22 package size (1.0" × 2.1" DIP) makes it
an excellent choice in multichannel systems for maximum chan­nel density. The 0.35" height also facilitates applications with
limited board clearance.

1B22

DEMODULATORMODULATOR

RECTIFIER/

LOOP SUPPLY

PROT

OUT
HI

OUT
LO

REV. B

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Fax: [phone] © Analog Devices, Inc., 2000

1B22–SPECIFICATIONS

(typical @ +25ⴗC and VS = ⴞ15 V, V

= +24 V, unless otherwise noted)

LOOP

Model 1B22AN

INPUT SPECIFICATIONS

Factory Calibrated, User Selectable 0 V to +5 V, 0 V to +10 V
Input Impedance

0 V to +10 V Input Range 50 kΩ
0 V to +5 V Input Range 25 kΩ

OUTPUT SPECIFICATIONS

Current Output Range, User Selectable 4 to 20 mA, 0 to 20 mA
Load Compliance Range, V

Load Compliance Range, V

= +15 V 8 V min

LOOP

= +28 V 20 V min

LOOP

Maximum Output Current @ Input Overload 30 mA
Output Noise, 100 Hz Bandwidth 300 nA p-p

NONLINEARITY (% of Span) ± 0.02% (± 0.05% max)

ISOLATION

CMV, Input to Output Continuous 1500 V rms max
CMR, @ 60 Hz 90 dB min
Normal-Mode Output Protection 240 V rms Continuous
CMV Transient Protection IEEE-STD 472 (SWC)

ACCURACY

Warm-Up Time to Rated Performance 5 min
Total Output Error @ +25°C

Offset (V
Span (V

= 0 V) ± 60 µA

IN

= +10 V) ± 0.7% Full Scale

IN

vs. Temperature (–25°C to +85°C)

Offset ± 300 nA/°C
Span ± 50 ppm/°C

DYNAMIC RESPONSE

Settling Time to 0.1% of FS for 10 V Step 9 ms
Small Signal Bandwidth 400 Hz

POWER SUPPLY

Bipolar Input Supplies

Operating Voltage ± 15 V ± 5%
Quiescent Current ± 7.5 mA
Power Supply Rejection ± 0.01%/V

Loop Supply

Operating Voltage +14 V to +30 V
Operating Current, at Full-Scale Output 25 mA
Loop Supply Rejection ± 0.005%/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, Noncondensing 0 to 95% @ 60°C

CASE SIZE 1.0" × 2.1" × 0.35"

Specifications subject to change without notice.

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

AC1225 MATING SOCKET

PIN DESIGNATIONS

Pin Function

11 OUT HI

16 IN2
17 IN1
18 S. NODE
19 4 mA OFFSET
20 +15 V
21 ANA COM
22 –15 V
23 SYNC
24 V

LOOP

25 POWER COM
38 OUT LO

–2–

REV. B