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Cortina Systems LXT9785 and LXT9785E Advanced 8-Port 10/100 Mbps PHY Transceivers
LXT9785/LXT9785E
Datasheet
249241, Revision 11.0
16 April 2007
7.0 Register Definitions
Table 100
Trim Enable Register (Address 27, Hex 1B)
Bit
Name
Description
Type5
Default
15:13
Reserved
Write as 0, ignore on Read
R
N/A
12
Reserved
Write as 0, ignore on Read.
R/W
0
11:10
Per-Port
Rise Time
Control
00 = 3.3 ns
01 = 3.6 ns
10 = 3.9 ns
11 = 4.2 ns
Note:
Values represent nominal load conditions.
R/W
LSHR1,2
9AMDIX_EN
0 = Disable auto MDI/MDIX
1 = Enable auto MDI/MDIX
R/W
LSHR1,3
8MDIX
0 = MDI, transmit on pair A (TPFIN
n/TPFIPn) and receive on
pair B (TPFON
n/TPFOPn)
1 = MDIX transmit on pair B (TPFON
n/TPFOPn) and receive
on pair A (TPFIN
n/TPFIPn)
Note:
Manual MDI/MDIX selection (This bit is ignored when
Register bit 27.9 = 1).
Note:
BGA15 does not support the MDIX hardware
configuration.
R/W
LSHR1,4
7
Analog
Loopback
0 = Disable analog loopback
1 = Enable analog loopback (twisted-pair transmit outputs are
active)
Note:
In fiber mode, SD for the port must be asserted.
R/W
0
6
Dis_EN
DTE Discovery Process Enable.
0 = Disable DTE discovery process
1 = Enable DTE discovery process
Restart auto-negotiation after writing to this bit to ensure
proper operation.
R/W
0
5
Reserved
Write as 0, ignore on Read.
R/W
0
4
Power_EN
Power Enable (Requires Auto-Negotiation Enable
Register bit 0.12 = 1).
0 = Remote-Power DTE not discovered; process may not be
complete.
1 = Potential Remote-Power DTE discovered; indication to
turn on power over the cable.
R0
1. LSHR = Default value is derived from a single device input pin state or a group of device input pin states as
the pin(s) are latched at startup or hardware reset.
2. Default values for Register bits 27.11:10 are determined by the TxSLEW pins.
3. Default value for Register bit 27.9 is determined by the AMDIX_EN pin.
4. Default value for Register bit 27.8 is determined by the MDIX pin. BGA15 does not support the MDIX
hardware configuration. The BGA15 default = 0.
5. R/W = Read/Write, R = Read Only, LH = Latching High – cleared when read.