ICS1893CF Data Sheet Rev. J - Release
Chapter 4 Operating Modes Overview
4.1.2 Specific Reset Operations
This section discusses the following specific ways that the ICS1893CF can be reset:
• Hardware reset (using the RESETn pin)
• Power-on reset (applying power to the ICS1893CF)
• Software reset (using Control Register bit 0.15)
Note: At the completion of a reset (either hardware, power-on, or software), the ICS1893CF sets all
registers to their default values.
4.1.2.1 Hardware Reset
Entering Hardware Reset
Holding the active-low RESETn pin low for a minimum of five REF_IN clock cycles initiates a hardware
reset (that is, the ICS1893CF enters the reset state). During reset, the ICS1893CF executes the steps
listed in Section 4.1.1.1, “Entering Reset”.
Exiting Hardware Reset
After the signal on the RESETn pin transitions from a low to a high state, the ICS1893CF completes in 640
ns (that is, in 16 REF_IN clocks) steps 1 through 5, listed in Section 4.1.1.2, “Exiting Reset”. After the first
five steps are completed, the Serial Management Port is ready for normal operations, but this action does
not signify the end of the reset cycle. The reset cycle completes when the transmit clock (TXCLK) and
receive clock (RXCLK) are available, which is typically 53 ms after the RESETn pin goes high. [For details
on this transition, see Section 9.5.16, “Reset: Hardware Reset and Power-Down”.]
Note:
1. The MAC Interface is not available for use until the TXCLK and RXCLK are valid.
2. The Control Register bit 0.15 does not represent the status of a hardware reset. It is a self-clearing bit
that is used to initiate a software reset.
4.1.2.2 Power-On Reset
Entering Power-On Reset
When power is applied to the ICS1893CF, it waits until the potential between VDD and VSS achieves a
minimum voltage before entering reset and executing the steps listed in Section 4.1.1.1, “Entering Reset”.
After entering reset from a power-on condition, the ICS1893CF remains in reset for approximately 20 µs.
(For details on this transition, see Section 9.5.15, “Reset: Power-On Reset”.)
Exiting Power-On Reset
The ICS1893CF automatically exits reset and performs the same steps as for a hardware reset. (See
Section 4.1.1.2, “Exiting Reset”.)
Note: The only difference between a hardware reset and a power-on reset is that during a power-on
reset, the ICS1893CF isolates its RESETn input pin. All other functionality is the same. As with a
hardware reset, Control Register bit 0.15 does not represent the status of a power-on reset.
ICS1893CF, Rev. J, 08/11/09
August, 2009
Copyright © 2009, Integrated Device Technology, Inc.
All rights reserved.
11
IDT [ INTEGRATED DEVICE TECHNOLOGY ]
