KS8721SL-EVAL Micrel Inc, KS8721SL-EVAL Datasheet - Page 30

• Manufacturer Part Number: KS8721SL-EVAL
• Description: BOARD EVAL EXPERIMENT KS8721SL
• Manufacturer: Micrel Inc

Specifications of KS8721SL-EVAL

• Main Purpose: Interface, Ethernet Controller (PHY and MAC)
• Embedded: No
• Utilized Ic / Part: KSZ8721SL
• Primary Attributes: 1 Port, 100BASE-TX/100BASE-FX/10BASE-T
• Secondary Attributes: MII, RMII, Auto MDI, MDIX, >130 Meter Cable Driver, LDO, IEEE802.3u Compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 576-1010

KS8721BL/SL (3.3V Single Power Supply 10/100BaseTX/FX MII Physical Layer Transceiver)
Power Management
100BT FX Mode
The KS8721BL/SL offers the following modes for power management:
100BT FX mode is activated when FXSD/FXEN is higher 0.6V (This pin has a
default pull down). Under this mode, the auto-negotiation and auto-MDIX
features are disabled.
In fiber operation FXSD pin should connect to the SD (signal detect) output
of the fiber module. The internal threshold of FXSD is around ½ Vdd +/-
50mV (1.25V+/-0.05V). Above this level, it is considered Fiber signal
detected, and the operation is summarized in the following table:
To ensure a proper operation, the swing of fiber module SD should cover
the threshold variation. A resistive voltage divider is recommended to adjust
the SD voltage range.
FEF (Far End Fault), repetition of a special pattern, which consists of 84-one
and 1-zero, is generated under “FX mode with no signal detected”. The
purpose of FEF is to notify the sender of a faulty link. When receiving a FEF,
the LINK will go down to indicate a fault, even with fiber signal detected.
The transmitter does not affect by receiving a FEF and still sends out its
normal transmit pattern from MAC. FEF can be disabled by strapping pin27
low, please refer to “Strapping Options” section.
FXSD/FXEN
Less than 0.6V
Less than 1.25V,
but greater than 0.6V
Greater than 1.25
Power Down Mode: This mode can be achieved by writing to
Register 0.11 or pulling pin 30 PD# Low.
Power Saving Mode: writing to register 1fh.10 can disable this
mode. The KS8721BL/SL will then turn off everything except for
the Energy Detect and PLL circuits when the cable is not installed.
In other words, the KS8721BL/SL will shutdown most of the
internal circuits to save power if there is no link. Power Saving
mode will be in his most effective state when Auto-Negotiation
Mode is enable.
- 30 -
Condition
100TX mode
FX mode
No signal detected
FEF generated
FX mode
Signal detected
KS8721BL/SL Preliminary Rev 0.90
Aug, 2003