User`s guide

A-4 Appendix A
Pinout & External Circuit Differences
The FTT-10A transceiver has a number of built-in functions resulting in fewer pins and simpler external
circuitry than the FTT-10 transceiver. Simplification of external circuitry has been qualified with a layout
optimized for the FTT-10A transceiver as documented in chapter 2 of this user's guide. For information on
existing PC board designs, see the following section.
FTT-10A Pin FTT-10 Pin Changes in Pin Function in the FTT-10A Transceiver
1 VCC 1 VCC None
2 NET_B 5 NET_B None
3 NET_A 6 NET_A None
4 RxD 7 RxD None
5 TXD 8 TXD/
CLKSEL1
The clock select function is multiplexed with the TXD pin in the
FTT-10 transceiver and the CLKSEL1 pin been eliminated due to
automatic input clock detection. The TXD pin remains without the
CLKSEL1 function. To prevent a possible, brief transient on the
network when the Neuron Chip goes through its reset process,
the 47kohm CLKSEL1 resistor R1 as defined in the LONWORKS
FTT-10 Free Topology Transceiver User's Guide figure 2.1 must
be removed.
6 CLK 10 CLK None
7 T1 11 T1 None
8 GND 12 GND None
9 T2 13 T2 None
No pin 9 RESET The FTT-10A transceiver has built-in reset function and therefore
has no reset pin. This eliminates the need for pulse-stretching
LVI and RC circuitry required by the FTT-10 transceiver. An LVI,
if used, should be selected based on Neuron Chip and application
electronics requirements.
No pin 3 CLKSEL0 The FTT-10A transceiver automatically detects the frequency of
the incoming clock and configures itself accordingly. The FTT-
10A transceiver has no CLKSEL0 pin.
No pin 4 TXEN The FTT-10A transceiver uses activity on TXD to determine when
to enable transmission, and accordingly has no TXEN pin.
Applications that require a transmit indicator LED can continue to
use a buffered CP2 signal.
No pin 2 RX_ACTIVE The FTT-10A transceiver uses activity on TXD to determine when
to enable transmission in a repeater configuration, and
accordingly has no RX_ACTIVE pin. Applications that require a
received indication LED can use a buffered RXD signal.