• Functional Description
• Input and Output Ranges
• Available Models
• Specifications

The 7B35 is a single-channel signal conditioning current input module that interfaces with two-wire transmitters, providing an isolated protected precision output of either +1 V to +5 V or +2 V to +10 V. Model 7B35 features an isolated 24 V DC loop power supply for driving the transmitter. To accurately measure low level signals in electrically noisy environments, 1500 V rms of galvanic transformer-based isolation with a common mode rejection (CMR) of 105 dB @ 50/60 Hz is provided. Rated to operate with a nominal +24 V DC supply, Model 7B35 is mix-and-match and hot-swappable with other 7B Series input modules, so it can be inserted or removed from any socket in the same backplane without disturbing system power.

Inside the 7B35 Series Module
The two input pins of Model 7B35 are each fully protected up to 120 V rms . The current input signal is converted to a voltage, then filtered by a one-pole 100 Hz filter. Amplitude modulation is used to implement transformer isolation (1500 V rms input-to-output and power). Isolated front-end circuitry power is supplied by a DC/DC converter. The isolated transmitter loop power supply is unregulated and will provide a voltage that is proportional to the voltage used to power the 7B35 module. The isolated voltage provided by the 7B35 is between 13 V DC and 34 V DC for loop currents between 4 mA and 20 mA and supply voltages between 20.4 V DC and 26.4 V DC. The output section contains a two-pole low pass filter (-3 dB @100 Hz), a buffer amplifier and power oscillator. The two-pole output filter and subsequent buffer ensures that a low noise, low impedance (<1 ) signal is available at the output to drive loads down to 2 k.

Figure 1. 7B35 Functional Block diagram

Inputs Two-Wire Transmitter, 4 mA to 20 mA Output Options +1 V to +5 V 0 V to +10 V

Figure 2. 7B35 Input Field Connections

---

7B35 Models Available

Model	Input Range	Output Range
7B35-01-1	+4 mA to +20 mA1	+1 V to +5 V
7B35-01-2	+4 mA to +20 mA1	+2 V to +10 V

¹Isolated 24 V loop power provided by Model 7B35.

7B35 Specifications
(typical @ +23℃ ±5℃ and V_s = +24 V dc)

Description	Model 7B35
Input Range1
Standard Range	4 mA to 20 mA
Custom Ranges	Not Available*
Input Loop Supply Voltage, Isolated	+24 V dc @ ILoop = 20 mA
Output Range (RL > 2 k)	+1 V to +5 V or +2 V to +10 V
Accuracy1
Initial @ +25℃	±0.01% Span (±0.1% Span, maximum)
Nonlinearity2	±0.02% Span, maximum
Input Offset vs. Temperature	N/A3
Span vs. Temperature	±40 ppm/℃
Output Offset vs. Temperature	±0.003% span/℃
Output Noise
5 MHz Bandwidth	60 mV peak
10 Hz to 100 kHz Bandwidth	0.9 mV rms
0.1 Hz to 10 Hz Bandwidth	4 µV peak
Bandwidth, -3 dB	100 Hz
Output Rise Time, 10% to 90% Span	5 ms
Common-Mode Voltage (CMV)
Input-to-Output and Power	1500 V rms continuous
Common Mode Rejection (CMR)
Input-to-Output and Power @ 50/60 Hz	105 dB
Input Protection	120 V rms, continuous ±35 V dc, continuous
Input Transient Protection	ANSI/IEEE C376.90.1-1989 IEEE-STD 472 IEC 255-4, Class II
Output Resistance	< 1
Voltage Output Protection	Continuous Short to Ground
Power Supply
Voltage Range, Operating	+14 V dc to +35 V dc
Current	+25 mA, maximum
Sensitivity	±0.0001%/% of Vs
Mechanical dimensions	1.663" x 2.11" x 0.563" (42.24 mm x 53.6 mm x 14.3 mm)
Weight	60 grams
Environmental
Temperature Range
Operating	-40℃ to +85℃
	-40℃ to +85℃
Relative Humidity, 24 hours	0 to 90% @ +60℃ noncondensing
ESD Sensitivity	IEC 801-2, Level 2
RFI Susceptibility	±0.5% Span error @ 400 MHz, 5 Watt, 3 ft

Warm-up time required to meet specifications is approximately 10 minutes.
* Contact factory for OEM requirements.
¹Includes the combined efStoragefects of repeatability, hysteresis, and nonlinearity.
²Nonlinearity is calculated using best-fit straight line method.
³Input offset term is included in the output offset specification.
Specifications subject to change without notice.