Appendix 2 - 6

The designer can connect the UT63M14x to the data bus via a

short-stub (direct-coupling) connection or a long-stub

(transformer-coupling) connection. Use a short-stub connection

when the distance from the isolation transformer to the data bus

does not exceed a one-foot maximum. Use a long-stub

connection when the distance from the isolation transformer

exceeds the one-foot maximum and is less than twenty feet.

Figure 5 shows various examples of bus coupling

configurations. The UT63M14x series transceivers are designed

to function with MIL-STD-1553A and 1553B compatible

transformers.

Note:

1. The 24-lead flatpack internally connects TXOUT to RXIN and TXOUT to

RXIN for each channel.

RECOMMENDED THERMAL PROTECTION

All packages should mount to or contact a heat removal rail

located in the printed circuit board. To insure proper heat

transfer between the package and the heat removal rail, use a

thermally-conductive material between the package and the heat

removal rail. Use a material such as Mereco XLN-589 or

equivalent to insure heat transfer between the package and heat

removal rail.

Figure 8. Transceiver Test Circuit MIL-STD-1553B

Figure 5. Bus Coupling Configuration

55 OHMS

55 OHMS

20 FT MAX

1:1.4

Note:

+5V DC OPERATION

1:1.79

1:2.5

SHORT-STUB

DIRECT COUPLING

1 FT. MAX.

LONG-STUB

TRANSFORMER COUPLING

TXOUT

RXIN

RXIN

TXOUT