Frequently asked questions

• What is the receiver watchdog timer?
• How are the pins configured for Intel and Motorola bus interfaces in the SC28L91 and SC28L92 parts?
• How do you allow high input voltages while operating at 3.3V?
• How long does it take for the oscillator to start up after taking it out of low-power mode?
• When does the transmitter need to be enabled/disabled in the transmitter RTS control mode?

Q	What is the receiver watchdog timer?
A	When enabled, the watchdog timer generates a receiver interrupt if the receiver FIFO has not been accessed within 64 bit times of the receiver 1X clock.

Q	How are the pins configured for Intel and Motorola bus interfaces in the SC28L91 and SC28L92 parts?
A	The four pins are configured as follows: Intel Motorola I/M Input (high/open) I/M Input (low) WRN Input R/WN Input RDN Input DACKN Output IP6 Input IACKN Input

Q	How do you allow high input voltages while operating at 3.3V?
A	The following external parts can be used: NXP PicoGate logic buffers/drivers A resistor with a clamp diode A line driver such as an RS-232 driver/receiver

Q	How long does it take for the oscillator to start up after taking it out of low-power mode?
A	It takes between 5ms and 6ms. 6ms is a good wait time.

Q	When does the transmitter need to be enabled/disabled in the transmitter RTS control mode?
A	In simplex communication, it becomes necessary for a transceiver device to change its direction of communication from transmitting to receiving. This is similar to the function of the push-to-talk switch on a handheld radio.

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