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TCA9617A

SCPS244 – JUNE 2013

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B-side Pedestal

Figure 5 depicts the pedestal on the B side of the device. At point 1 in Figure 5 the slave device is driving the B-

side low. As the slave releases and the B-side rises, it will only be allowed to rise to 0.5 V until the A-side rises

Due to nature of the B-side pedestal and the static offset voltage, there will be a slight overshoot (point 2) as the

behavior provided the system is designed with RCs greater than 20 ns. Note that care should be taken to limit

the pull-up strength when devices with rise time accelerators are present on the B side. Excessive overshoot on

the B-side pedestal may cause devices with rise time accelerators to trip prematurely if the accelerator

Figure 5. B-side Pedestal

B-side Inverted Pedestal

To decrease the propagation delay of the TCA9617A, an inverted pedestal (Figure 6) is used on the B side of the

V for a short period (point 1) and then the B-side will rise to the static offset voltage of 0.5 V (point 2). This

design allows the B-side to drive to logic low much faster than simply driving to the static offset as driving to the

static offset voltage requires that the fall time be slowed to prevent ringing.

Figure 6. B-side Inverted Pedestal

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