ksz8021rnli Micrel Semiconductor, ksz8021rnli Datasheet - Page 23

• Manufacturer Part Number: ksz8021rnli
• Description: 10base-t/100base-tx Phy With Rmii Support
• Manufacturer: Micrel Semiconductor

Micrel, Inc.
Slow Oscillator Mode
Slow Oscillator Mode is used to disconnect the input reference crystal/clock on XI (pin 8) and select the on-chip slow
oscillator when the KSZ8021/31RNL device is not in use after power-up. It is enabled by writing a one to register 11h, bit
[5].
Slow Oscillator Mode works in conjunction with Power Down Mode to put the KSZ8021/31RNL device in the lowest power
state with all internal functions disabled, except for the MII management interface. To properly exit this mode and return to
normal PHY operation, use the following programming sequence:
Reference Circuit for Power and Ground Connections
The KSZ8021/31RNL is a single 3.3V supply device with a built-in regulator to supply the 1.2V core. The power and
ground connections are shown in Figure 7 and Table 6 for 3.3V VDDIO.
August 2010
1. Disable Slow Oscillator Mode by writing a zero to register 11h, bit [5].
2. Disable Power Down Mode by writing a zero to register 0h, bit [11].
3. Initiate software reset by writing a one to register 0h, bit [15].
Power Pin
VDD_1.2
VDDA_3.3
VDDIO
Figure 7. KSZ8021/31RNL Power and Ground Connections
Pin Number
Table 6. KSZ8021/31RNL Power Pin Description
14
1
2
Description
Decouple with 2.2uF and 0.1uF capacitors-to-ground.
Connect to board’s 3.3V supply through ferrite bead.
Decouple with 22uF and 0.1uF capacitors-to-ground.
Connect to board’s 3.3V supply for 3.3V VDDIO.
Decouple with 22uF and 0.1uF capacitors-to-ground.
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KSZ8021RNL / KSZ8031RNL
M9999-082710-1.0