KSZ8862-16_10 MICREL [Micrel Semiconductor], KSZ8862-16_10 Datasheet - Page 25

• Manufacturer Part Number: KSZ8862-16_10
• Description: 2-Port Ethernet Switch with Non-PCI Interface and Fiber Support
• Manufacturer: MICREL [Micrel Semiconductor]

Forced mode and auto-negotiation disabled mode settings for 10BASE-FL fiber use the same registers (P1MBCR,
P1CR4). These registers are summarized in the Register Map section.
10BASE-T Transmit
The 10BASE-T driver (port 2 only) is incorporated with the 100BASE-TX driver to allow for transmission using the same
magnetic. They are internally wave-shaped and pre-emphasized into outputs with typically 2.3V amplitude. The harmonic
contents are at least 27dB below the fundamental frequency when driven by an all-ones Manchester-encoded signal.
10BASE-T Receive
On the receive side (port 2 only), input buffers and level detecting squelch circuits are employed. A differential input
receiver circuit and a phase-locked loop (PLL) perform the decoding function. The Manchester-encoded data stream is
separated into clock signal and NRZ data. A squelch circuit rejects signals with levels less than 400mV or with short pulse
widths to prevent noise at the RXP-or-RXM input from falsely triggering the decoder. When the input exceeds the squelch
limit, the PLL locks onto the incoming signal and the KSZ8862M decodes a data frame. The receiver clock is maintained
active during idle periods in between data reception.
LED Driver
The device provides a current mode fiber LED driver (port 1 only). The edge-enhanced current mode does not require any
output wave shaping. The drive current of the LED driver can be programmed through ATCR0 [7:6] register in Bank 44.
Post Amplifier
The chip also includes a post amplifier (port 1 only). The post amplifier is intended for interfacing the output of the pre-
amplifier of the PIN diode module. The minimum sensitivity of the amplifier is 2.5 mV (rms) for 10Base-FL receive on pin
RXM1 or 16mV (rms) for 100Base-SX receive on pin RXM1.
Power Management
The KSZ8862M features per port power-down mode. To save power, the user can power-down the port that is not in use
by setting bit 11 in either P1CR4 or P1MBCR register for port 1 and setting bit 11 in either P2CR4 or P2MBCR register for
port 2. To bring the port back up, reset bit 11 in these registers.
In addition, there is a full switch power-down mode. This mode shuts the entire switch down, when the PWRDN (pin 36) is
pulled down to low.
MDI/MDI-X Auto Crossover
To eliminate the need for crossover cables between similar devices, the KSZ8862M supports HP-Auto MDI/MDI-X and
IEEE 802.3u standard MDI/MDI-X auto crossover on port 2. HP-Auto MDI/MDI-X is the default.
The auto-sense function detects remote transmit and receive pairs and correctly assigns the transmit and receive pairs for
the KSZ8862M device. This feature is extremely useful when end users are unaware of cable types in addition to saving
on an additional uplink configuration connection. The auto-crossover feature can be disabled through the port control
registers.
The IEEE 802.3u standard MDI and MDI-X definitions are:
Micrel, Inc.
August 2010
MDI
RJ45 Pins
1
2
3
6
Table 1. MDI/MDI-X Pin Definitions
Signals
TD+
TD-
RD+
RD-
MDI-X
RJ45 Pins
1
2
3
6
25
Signals
RD+
RD-
TD+
TD-
KSZ8862-16/32MQL
M9999-081310-3.1