Datasheet
KSZ8081MNX/RNB
DS00002202C-page 56 2016-2018 Microchip Technology Inc.
7.11 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 7-13 for 3.3V and 2.5V VDDIO.
FIGURE 7-13: 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 2 mA LED
indicator. It is okay to use internal pull-up or external pull-up resistor for the LED pin pull-up strap function, and use an
external 0.75
k to 1 k 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.
LED PIN
220Ω
4.7kΩ
PULL_UP
KSZ8081MNX/RXB
VDDIO = 3.3V, 2.5V
LED PIN
220Ω
FLOAT
KSZ8081MNX/RXB
VDDIO = 3.3V, 2.5V
LED PIN
220Ω
PULL-DOWN
KSZ8081MNX/RXB
VDDIO = 3.3V, 2.5V
1kΩ