LAN9220_12 Datasheet, PDF (47/151 Pages) SMSC Corporation – 16-bit Non-PCI Small Form Factor 10/100 Ethernet Controller with Variable Voltage I/O & HP Auto-MDIX Support

16-bit Non-PCI Small Form Factor 10/100 Ethernet Controller with Variable Voltage I/O & HP Auto-MDIX Support
Datasheet
3.10.3.2
Energy Detect Power-Down
This power-down mode is activated by setting the Phy register bit 17.13 to 1. Please refer to Section
5.5.8, "Mode Control/Status," on page 122 for additional information on this register. In this mode when
no energy is present on the line, the PHY is powered down, with the exception of the management
interface, the SQUELCH circuit and the ENERGYON logic. The ENERGYON logic is used to detect
the presence of valid energy from 100Base-TX, 10Base-T, or Auto-negotiation signals
In this mode, when the ENERGYON signal is low, the PHY is powered-down, and nothing is
transmitted. When energy is received - link pulses or packets - the ENERGYON signal goes high, and
the PHY powers-up. It automatically resets itself into the state it had prior to power-down, and asserts
the INT7.1 bit of the register defined in Section 5.5.11, "Interrupt Source Flag," on page 125. If the
ENERGYON interrupt is enabled, this event will cause an interrupt to the host. The first and possibly
the second packet to activate ENERGYON may be lost. When 17.13 is low, energy detect power-down
is disabled.
3.11 Detailed Reset Description
The LAN9220 has four reset sources:
„ Hardware Reset Input Pin (nRESET)
„ Soft Reset (SRST)
„ PHY Soft Reset via PMT_CTRL bit 10 (PHY_RST)
„ PHY Soft Reset via PHY Basic Control Register (PHY REG 0.15)
Table 3.11 shows the effect of the various reset sources on the LAN9220's circuitry.
Note:
For proper operation, the LAN9220 must be reset on power-up via the hardware reset input
(nRESET) or soft reset (SRST). To accomplish this, nRESET should be asserted for the
minimum period of 30ms at power-up. Alternatively, a soft reset may be performed following
power-up by setting the SRST bit of the HW_CFG register once the READY bit in the
PMT_CTRL register has been set. Refer to Section 3.11.1, "Hardware Reset Input (nRESET)"
and Section 3.11.3, "Soft Reset (SRST)" for additional information.
Table 3.11 Reset Sources and Affected Circuitry
RESET
SOURCE
HBI
NASR
Note REGISTERS
PLL 3.13 Note 3.13 MIL
nRESET X
X
X
X
SRST
X
X
PHY_RST
PHY REG 0.15
MAC
PHY
Note 3.11
EEPROM MAC
ADDR.
RELOAD
Note 3.12
X
X
X
X
X
X
X
CONFIG.
STRAPS
LATCHED
X
Note 3.11 After any PHY reset, the application must wait until the “Link Status” bit in the PHY’s “Basic
Status Register” (PHY Reg. 1.2) is set before attempting to transmit or receive data.
Note 3.12
After a power-up, nRESET or SRST, the LAN9220 will automatically check for the
presence of an external EEPROM. After any of these resets the application must verify
that the EPC Busy Bit (E2P_CMD, bit 31) is cleared before attempting to access the
EEPROM, or change the function of the GPO/GPIO signals, or before modifying the
ADDRH or ADDRL registers in the MAC.
Note 3.13 HBI - “Host Bus Interface”, NASR - Not affected by software reset.
SMSC LAN9220
47
DATASHEET
Revision 2.9 (03-01-12)