Analog Devices 1B22 Datasheet

a		Programmable, Isolated
		Voltage-to-Current Converter
		1B22

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: 300 nA/ C Low Gain Tempco: 50 ppm/ C Low Nonlinearity: 0.02%

High CMR: 90 dB min

Small Package: 1.0" 2.10" 0.35"

Meets IEEE STD 472: CMV Transient Protection (SWC)

FUNCTIONAL BLOCK DIAGRAM

IN1					1B22	OUT
IN2		REF
	RESISTOR		SIGNAL			HI
4mA	NETWORK		ISOLATION
OFFSET						OUT
S. NODE
		MODULATOR		DEMODULATOR		LO
						PROT
SYNC			POWER
			ISOLATION
+15V					RECTIFIER/
–15V		OSCILLATOR
					LOOP SUPPLY
A. COM

P. COM VLOOP

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

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

REV. B

Information furnished by Analog Devices is believed to be accurate and 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.

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-to- current 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.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: [phone]	World Wide Web Site: http://www.analog.com
Fax: [phone]	© Analog Devices, Inc., 2000

1B22–SPECIFICATIONS (typical @ +25 C and VS = 15 V, VLOOP = +24 V, unless otherwise noted)

Model	1B22AN
INPUT SPECIFICATIONS
Factory Calibrated, User Selectable	0 V to +5 V, 0 V to +10 V
Input Impedance	50 kΩ
0 V to +10 V Input Range
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, VLOOP = +15 V	8 V min
VLOOP = +28 V	20 V min
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	±60 µA
Offset (VIN = 0 V)
Span (VIN = +10 V)	±0.7% Full Scale
vs. Temperature (–25°C to +85°C)	±300 nA/°C
Offset
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	±15 V ± 5%
Operating Voltage
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	–25°C to +85°C
Rated Performance
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

1

OUT HI

16IN2

17IN1

18S. NODE

194 mA OFFSET

20+15 V

21ANA COM

22–15 V

23SYNC

24VLOOP

25POWER COM

38

OUT LO

–2–

REV. B