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ARCNET 5 Port HUB Controller
Datasheet
Revision 1.1 (07-24-07) Page 20 SMSC TMC2005-JT
DATASHEET
PORT GROUP
The five ports can be divided into three groups (group A: two ports, group B: two ports, extension port: one port) and
each group can select TX/RX polar, noise cut mode, and big jitter mode respectively. Select pins for each group are
as follows:
FUNCTION GROUP A GROUP B EXTENSION
RECEIVE RXINA0, 1 RXINB0, 1 EXTRX
TRANSMIT TXENA0, 1 TXENB0, 1 EXTTX
RX POLARITY SA SB SE
TX POLARITY LA LB LE
TX CONTROL MA MB ME
NOISE CUT nMBA nMBB nMBE
BIG JITTER nBJA nBJB nBJE
EXTENSION nEXTOD
Various Setup
Example For Operation Mode Setup To Each Port
SA, SB, SE LA, LB, LE MA, MB, ME RX POLAR TX POLAR TRANSCEIVER
1 0 1 Active Low Active Low HYC2485S/HYC2488S
0 1 0 Active High Active High Optical Transceiver
0 0 1 Active High Active Low HYC9088/HYC9068
1 1 1 Active Low Active High RS485 Transceiver
Note for Unused port
Unused ports can be left open because RX port (RX input), RX polar (S input), TX polar (L input), TX control (M input)
pins have internal pull-up resistors. Because of internal pull-up resistors, select pins for noise cut (nMB input), big
jitter (nBJ input) can be left open when used for setting “OFF”.
Example for Power-On Reset Circuit
FIGURE 9 - POWER-ON RESET