SLASEC8B February 2017 – January 2019 PGA460-Q1
A center-tap transformer is typically paired with the transducer to convert a DC voltage to a high-sinusoidal AC voltage. The center tap is a contact made to a point halfway along the primary winding of the transformer. The center tap is supplied with the DC voltage that is then multiplied on the secondary side based on the turns ratio of the transformer. Figure 138 shows the typical pinout of a center-tap transformer where pin 2 is the center tap, pins 1 and 3 are connected to OUTB and OUTA, pin 4 is connected to the positive terminal of the transducer, and pin 6 is connected to ground.
Two modes to generate the transducer voltage using the center tap transformer are available. These modes are defined as follows:
The primary coils have the same number of turns. The rate of change of current in the primary coil generates a voltage in the secondary coil of the transformer, which is connected to the transducer. The direction of current in the primary coils generates voltages of opposite polarity in the secondary coils which effectively doubles the peak-to-peak voltage in the secondary coil.
The rate of change of current in the primary coil generates a voltage in the secondary coil of the transformer, which is connected to the transducer. The center tap of the transformer is not required for this mode, and can be left floating. Instead, the reference voltage is connected to an outermost primary-side terminal (pin 3) and either OUTA or OUTB is connected to the other primary-side terminal (pin1).