Datasheet

SLDU010
TI CONFIDENTIAL – NDA Restrictions
Page 17 of 50
Figure 12. OWI Activation Circuit
4.4 OWI Transceiver – VOUT1
Once the OWI transceiver in the PGA400-Q1 has been activated either by the OWI activation
pulse, or by a direct SPI write the TI-GER needs to communicate with the PGA400-Q1 with the
proper OWI signals. A simple circuit is used to convert the two-signal TI-GER USART (TX/RX)
into the single wire OWI signal. The circuit operates in a way that the receiver is always listening
even while transmitting so there is always a loop-back feature that the GUI uses to ensure the
correct information was transmitted out of the TI-GER. When a read is requested from the
PGA400-Q1, the VOUT1 signal drives the OWI signal and the TI-GER receives it. There are no
issues of possible bus contention and the OWI transceiver circuit ensures that only the RX line is
affected by the data transmitted out of the PGA400-Q1. The OWI transceiver circuit is shown
below.