7B40

Rev. 0 | Page 2 of 8

GENERAL DESCRIPTION

The 7B40 is a single-channel signal conditioning module that

interfaces, amplifies and filters unipolar and bipolar millivolt

and voltage inputs and provides a protected precision output of

either +1 V to +5 V or 0 V to +10 V. Model 7B40 features a

nonlinearity of +0.02% maximum and an accuracy of +0.1%

maximum (+0.01% typical). 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 110 dB @50/60 Hz and a normal mode

rejection (NMR) of 100 dB @50/60 Hz are provided. Rated to

operate with a nominal +24 VDC supply, Model 7B40 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.

The floating differential input of Model 7B40 is fully protected

up to 240 V rms line voltage. A one-pole 10 KHz filter

preconditions the input signal prior to amplification by a low

drift input amplifier. 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 output section contains a four-pole low

pass filter (-3 dB @ 10KHz), a buffer amplifier and a power

oscillator. The four-pole output filter and subsequent buffer

ensures that a low noise, low impedance (<1Ω) signal is

available at the output to drive loads of 2 kΩ minimum.

Figure 2