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Setup and Operation
9
SLAU659B–February 2017–Revised March 2018
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PGA460-Q1 Ultrasonic Signal Conditioner EVM With Transducer User's
Guide
2.3.1 Transformer Driven
The transformer-driven configuration uses a center-tap transformer to boost the DC VPWR voltage to a
high-voltage sinusoidal driving signal at the secondary. The transformer installed on the daughtercard is a
fixed-type EPCOS B78416A2232A003. The transformer driven configuration is typically reserved for
closed-top transducers, which require higher driving voltages than open-top transducers. For this reason,
the closed-top 58.5-kHz muRata MA58MF14-7N is paired with the transformer.
To use the temperate or time decouple features, desolder the R40 resistor, which shorts the coupling
capacitor to GND by default.
To use separate transmitter and receiver sense elements, desolder the R36 resistor, which shorts the
return path of the transmitting net to the INP path of the PGA460-Q1. Install the receiver sense transducer
element to J14.
WARNING
The typical use case of the PGA460-Q1 EVM is intended to limit
and drive the transducer below 50 VRMS. The transformer may
generate a driving voltage of 50 VRMS or more at the transducer if
any of the following conditions or
modifications are applied:
• The supplied transformer is replaced with a high voltage transformer with an
increased turns ratio.
• The center-tap of the transformer is supplied with a voltage beyond typical
or recommended conditions.
• The PGA460-Q1 device is not current limited in software.
Use appropriate high voltage safety measures if operating the EVM
beyond 50 VRMS at the transducer.
2.3.2 Direct (Bridge) Driven
The direct driven configuration uses either a half-bridge or full-bridge to generate an alternating square
wave to drive the transducer. By default, the half-bridge driver configuration is enabled to allow the use of
single transducer for transmit and receive. The PGA460-Q1 cannot drive a single transducer in the full-
bridge configuration without the support of additional circuitry. Refer to the Application Note PGA460 Full-
Bridge Driver Solutions for Ultrasonic Transducers (SLAA780) for details on a full-bridge solutions. Given
that low-side drivers are integrated into the PGA460-Q1, an external 2-channel p-channel MOSFET
(FDC6506P) is required. In half-bridge configuration, only one channel is used.
The peak-to-peak drive voltage is referenced to VPWR and GND in half-bridge, and VPWR to –VPWR in
full-bridge. Because of the lower voltage generated at the transducer, the open-top 40-kHz muRata
MA40H1S-R is paired with the direct driver.
To enable the full-bridge driver for a bi-static transducer pair:
Step 1. Desolder the R35 resistor, which typically shorts the minus terminal of the transducer to
ground.
Step 2. Solder a 0-Ωshort at R34, which shorts the minus terminal of the transducer to the OUTB
driver.
Step 3. Solder a 1-kΩ0603 resistor at R30, which creates an OUTA based pulldown for the gate of
the second channel of the p-channel MOSFET.
Step 4. Desolder the R32 resistor, which typically shorts the plus terminal of the transmitting
transducer to the INP return path.
Step 5. Install the receiver sense transducer element to J11.
The decoupling feature is not available on the direct driven circuit of the daughtercard.
