KSZ8851-16MLLU TR Micrel, KSZ8851-16MLLU TR Datasheet - Page 23

• Manufacturer Part Number: KSZ8851-16MLLU TR
• Description: Ethernet ICs Single-Port Ethernet Controller (Automotive Grade)
• Manufacturer: Micrel

Specifications of KSZ8851-16MLLU TR

• Rohs: yes
• Product: Ethernet Controllers
• Package / Case: LQFP-48
• Mounting Style: SMD/SMT

LinkMD
The KSZ8851-16MLL LinkMD
problems such as open circuits, short circuits, and impedance mismatches.
LinkMD
the shape of the reflected signal. Timing the pulse duration gives an indication of the distance to the cabling fault with a
maximum distance of 200m and an accuracy of ±2m. Internal circuitry displays the TDR information in a user-readable
digital format in register P1SCLMD[8:0].
Note: cable diagnostics are only valid for copper connections – fiber-optic operation is not supported.
Access
LinkMD
Usage
LinkMD
P1CR[10] to enable manual control over the pair used to transmit the LinkMD
test enable bit, P1SCLMD [12], is set to ‘1’ to start the test on this pair.
When bit P1SCLMD[12] returns to ‘0’, the test is complete. The test result is returned in bits P1SCLMD[14:13] and the
distance is returned in bits P1SCLMD[8:0]. The cable diagnostic test results are as follows:
00 = Valid test, normal condition
01 = Valid test, open circuit in cable
10 = Valid test, short circuit in cable
11 = Invalid test, LinkMD
If P1SCLMD[14:13]=11, this indicates an invalid test, and occurs when the KSZ8851-16MLL is unable to shut down the
link partner. In this instance, the test is not run, as it is not possible for the KSZ8851-16MLL to determine if the detected
signal is a reflection of the signal generated or a signal from another source.
Cable distance can be approximated by the following formula:
P1SCLMD[8:0] x 0.4m for port 1 cable distance
This constant may be calibrated for different cabling conditions, including cables with a velocity of propagation that varies
significantly from the norm.
Media Access Control (MAC) Operation
The KSZ8851-16MLL strictly abides by IEEE 802.3 standards to maximize compatibility.
Inter Packet Gap (IPG)
If a frame is successfully transmitted, then the minimum 96-bit time for IPG is measured between two consecutive
packets. If the current packet is experiencing collisions, the minimum 96-bit time for IPG is measured from carrier sense
(CRS) to the next transmit packet.
Back-Off Algorithm
The KSZ8851-16MLL implements the IEEE standard 802.3 binary exponential back-off algorithm in half-duplex mode.
After 16 collisions, the packet is dropped.
Late Collision
If a transmit packet experiences collisions after 512 bit times of the transmission, the packet is dropped.
Flow Control
The KSZ8851-16MLL supports standard 802.3x flow control frames on both transmit and receive sides.
On the receive side, if the KSZ8851-16MLL receives a pause control frame, the KSZ8851-16MLL will not transmit the next
normal frame until the timer, specified in the pause control frame, expires. If another pause frame is received before the
current timer expires, the timer will be updated with the new value in the second pause frame. During this period (while it
is flow controlled), only flow control packets from the KSZ8851-16MLL are transmitted.
On the transmit side, the KSZ8851-16MLL has intelligent and efficient ways to determine when to invoke flow control. The
May 2012
Micrel, Inc.
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is initiated by accessing register P1SCLMD, the PHY special control/status & LinkMD
works by sending a pulse of known amplitude and duration down the MDI and MDI-X pairs and then analyzes
can be run at any time by ensuring that Auto-MDIX has been disabled. To disable Auto-MDIX, write a ‘1’ to
Cable Diagnostics
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failed
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uses time domain reflectometry (TDR) to analyze the cabling plant for common cabling
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pulse. The self-clearing cable diagnostic
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register (0xF4).
KSZ8851-16MLL/MLLI
M9999-050112-2.1