KSZ8895MQ_12 MICREL [Micrel Semiconductor], KSZ8895MQ_12 Datasheet - Page 38

• Manufacturer Part Number: KSZ8895MQ_12
• Description: Integrated 5-Port 10/100 Managed Ethernet Switch with MII/RMII interface
• Manufacturer: MICREL [Micrel Semiconductor]

Micrel, Inc.
KSZ8895RQ supports MAC5 RMII interfaces at the switch side:
When the device is strapped to normal mode by pin LED2_2 pull-down, the reference clock comes from SMTXC
which will be used as the device’s clock source. The external 25MHz crystal clock from pins X1/X2 will be ignored.
Note: In normal mode, the 50MHz clock from SMTXC will be used as the clock source for whole device. The PHY5
PMTXC/PMREFCLK pin can not be used as the clock source for whole device. The pin of PMTXC/PMREFCLK can
receive the 50MHz clock from PMRXC when the device is strapped to normal mode and an external 50MHz
reference clock comes in from pin SMTXC. In normal mode, the 50MHz clock on pin SMRXC can be disabled by
register, and the PMRXC 50MHz clock can be used when P5-RMII interface is used.
There is a register 12 bit 6 to monitor the status of the device for the clock mode or normal mode.
When using an external 50MHz clock source as RMII reference clock, the KSZ8895RQ should be set to normal
mode by pulling down its LED2_2 strap-in pin first before power up reset or warm reset. The normal mode of the
KSZ8895RQ device will start to work when it gets the 50MHz reference clock from pin SMTXC/SMREFCLK from an
external 50MHz clock source. For the RMII connection examples, please refer to app note in the design kit.
March 2012
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Supports 10Mbps and 100Mbps data rates.
Uses a single 50MHz clock reference (provided internally or externally): in internal mode, the chip provides a
reference clock from the SMRXC pin to the SMTXC pin and provides the clock to the opposite clock input pin
for RMII interface. In external mode, the chip receives 50MHz reference clock from an external oscillator or
opposite RMII interface.
Provides independent 2-bit wide (bi-bit) transmit and receive data paths.
For the detail of SW5-RMII (Port 5 MAC5 RMII) signals connection see the table below:
The KSZ8895RQ can provide a 50MHz reference clock for both MAC to MAC and MAC to PHY RMII
interfaces when SW5-RMII is used in the clock mode of the device (default with strap pin LED2_2 internal
pull-up for the clock mode).
The KSZ8895RQ can also receive a 50MHz reference clock from an external 50MHz clock source or
opposite RMII to SW5-RMII SMTXC pin when the device is set to normal mode (the strap pin LED2_2 is
pulled down).
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KSZ8895MQ/RQ/FMQ
M9999-032612-1.5