Datasheet

Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
August
19, 2015 64
Revision 1.4
Reference Circuits – LED Strap-In Pins
The pull-up, float, and pull-down reference circuits for the LED1/SPEED and LED0/NWAYEN strapping pins are shown in
Figure 23 for 3.3V and 2.5V VDDIO.
Figure 23. Reference Circuits for LED Strapping Pins
For using 1.8V VDDIO, should select parts with low 1.8V operation voltage and forwarding current IF about 2mA LED
indicator. It is ok using internal pull-up or external pull-up resistor for the LED pin pull-up strap function, and use an
external 0.75K to 1K pull-down resistor for the LED pin pull-down strap function.
Note: If
using RJ45 jacks with integrated LEDs and 1.8V VDDIO, a level shifting is required from LED 3.3V to 1.8V. For
example, use a bipolar transistor or a level shift device.