LAN8810I-AKZE Datasheet, PDF (89/100 Pages) Microchip Technology – GMII 10/100/1000 Ethernet Transceiver with HP Auto-MDIX Support

5.5.3
GMII 10/100/1000 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Power-On Reset Timing
Figure 5.3 illustrates the nRESET, configuration strap/pin, and CONFIG[3:0] timing requirements in
relation to power-on. A hardware reset (nRESET assertion) is required following power-up. For proper
operation, nRESET must be asserted for no less than t_rstia. The nRESET pin can be asserted at any
time, but must not be deasserted before t_purstd after all external power supplies have reached
operational levels. In order for valid configuration strap values to be read at power-up, the t_css and t_csh
timing constraints must be followed. In order for CONFIG[3:0] values to be read at power-up, the t_cs
and t_ch timing constraints must be followed. Refer to Section 3.6.1, "Hardware Reset (nRESET)," on
page 27 for additional information.
All External
Vopp
Power Supplies
nRESET
t_purstv
Configuration
Straps
Configuration Strap
Pins Output Drive
CONFIG[3:0]
t_purstd
t_rstia
t_css
t_csh
t_otaa
t_odad
t_cs
t_ch
Figure 5.3 Power-On Reset Timing
Table 5.12 Power-On Reset Timing Values
SYMBOL
DESCRIPTION
MIN
t_purstd
t_purstv
t_rstia
t_css
t_csh
t_otaa
t_odad
t_cs
t_ch
External power supplies at operational level to nRESET
25
deassertion
External power supplies at operational level to nRESET
0
valid
nRESET input assertion time
100
Configuration strap pins setup to nRESET deassertion 200
Configuration strap pins hold after nRESET deassertion 10
Output tri-state after nRESET assertion
Output drive after deassertion
40
CONFIG[3:0] setup to nRESET deassertion
0
CONFIG[3:0] hold after nRESET deassertion
1
TYP
MAX UNITS
mS
nS
μS
nS
nS
50
nS
800
nS
nS
uS
Note: Device configuration straps are latched as a result of nRESET assertion. Refer to Section
3.8.1.1, "Configuration Straps," on page 29 details. Configuration straps must only be pulled
high or low and must not be driven as inputs.
Note: nRESET deassertion must be monotonic.
SMSC LAN8810/LAN8810i
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DATASHEET
Revision 1.0 (02-06-13)