7B22

The 7B22 is a unity gain single-channel signal conditioning output module that interfaces and filters a +10 V input signal and provides an isolated precision output of +10 V. The output voltage appears at the 7B Series backplane screw terminal block. Model 7B22 features a nonlinearity of +0.02% maximum and an accuracy of +0.1% maximum (+0.01% typical). Providing 1500 V rms of galvanic transformer based isolation, output-to-input and power, the 7B22 offers a common mode rejection (CMR) of 100 dB @ 50/60 Hz to preserve the integrity of low level signals in noisy environments. The 7B22 is mix-and-match and hot-
swappable with other 7B Series modules, so it can be inserted or removed from any socket in the same backplane without disturbing system power. Model 7B22 is rated to operate with a nominal +24 VDC supply.

The input and floating isolated voltage output of Model 7B22 are protected up to +35 VDC. The input signal from the user's system is buffered and then used to modulate the amplitude of a square wave carrier. The modulated signal is transmitted across the signal transformer and demodulated to retrieve the original input voltage signal. This voltage is then filtered by a two-pole low pass 400 Hz filter. The nominal +24 VDC module supply voltage powers the input side of the 7B22. The oscillator on the input side provides the square wave carrier signal used by the modulator and also drives the power transformer. The signal at the secondary of the transformer is used in the demodulator and is also converted to a DC voltage that powers the circuit on the module's output. The two-pole output filter and subsequent buffer ensures that a low noise, low impedance (<1Ω) signal is available at the isolated output to drive loads down to 5 kΩ.