1894K-40LF IDT, 1894K-40LF Datasheet - Page 11

• Manufacturer Part Number: 1894K-40LF
• Description: Ethernet ICs 3.3V 10/100 PHY RMII
• Manufacturer: IDT

Specifications of 1894K-40LF

• Rohs: yes
• Part # Aliases: ICS1894K-40LF

Receive Error (RX_ER)
RX_ER is asserted for one or more REFIN periods to
indicate that an error (e.g. a coding error or any error that a
PHY is capable of detecting, and that may otherwise be
undetectable by the MAC sub-layer) was detected
somewhere in the frame presently being transferred from
the PHY. RX_ER transitions synchronously with respect to
REFIN. While CRS_DV is de-asserted, RX_ER has no
effect on the MAC.
Auto-MDI/MDIX Crossover
The ICS1894-40 includes the auto-MDI/MDIX crossover
feature. In a typical CAT 5 Ethernet installation the transmit
twisted pair signal pins of the RJ45 connector are crossed
over in the CAT 5 wiring to the partners receive twisted pair
signal pins and receive twisted pair to the partners transmit
twisted pair. This is usually accomplished in the wiring plant.
Hubs generally wire the RJ45 connector crossed to
accomplish the crossover. Two types of CAT 5 cables
(straight and crossed) are available to achieve the correct
connection. The Auto-MDI/MDIX feature automatically
corrects for miss-wired installations by automatically
swapping transmit and receive signal pairs at the PHY when
no link results. Auto-MDI/MDIX is automatic, but may be
disabled for test purposes by writing MDIO register 19 Bits
9:8 in the MDIO register. The Auto-MDI/MDIX function is
independent of Auto-Negotiation and preceeds
Auto-Negotiation when enabled.
Auto MDI/MDIX Table
Definitions:
straight
cross
IDT® 10BASE-T/100BASE-TX INTEGRATED PHYCEIVER WITH RMII INTERFACE
Default
AMDIX_EN
ICS1894-40
10BASE-T/100BASE-TX INTEGRATED PHYCEIVER WITH RMII INTERFACE
(pin 18)
0
1
1
x
x
transmit = TP_AP & TP_AN
receive = TP_BP & TP_BN
transmit = TP_BP & TP_BN
receive = TP_AP & TP_AN
AMDIX_EN
[Reg 19:9]
0
0
1
1
1
MDI_MODE
[Reg 19:8]
0
1
x
x
0
straight/cross (auto
straight/cross (auto
Configuration
Tx/Rx MDI
straight
straight
select)
select)
cross
AMDIX_EN (Pin 18) AMDIX enable pin with 20 kOhm
pull-up resistor
AMDIX_EN [19:9] MDIO register 19h bit 9
MDI_MODE [19:8] MDIO register 19h bit 8
11
ICS1894-40
PHYCEIVER
REV K 022412