Intel® 500 Series Chipset Family On-Package PCH Datasheet Volume 1

Datasheet

ID 631119
Date 13/07/2021 00:00:00
Public Content
Document Table of Contents

External CL_RST# Pin Driven/Open-drained Mode Support

The WLAN has transitioned to 1.8 V for external CL_​RST# pin, while PCH Controller Link I/O buffer still drives 3.3 V on this pin. This creates voltage incompatibility issue. In order to support either 1.8 V or 3.3 V on the device CL_​RST# pin, the PCH operates/controls the CL_​RST# pin as dual modes, which is determined by a Soft-strap bit:

  1. Driven Mode: To drive “1” on this pin, Controller Link turn-on the output enable and output as 1 to drive 3.3 V on this pin. This mode can only be enabled with older version of WLAN which is 3.3 V tolerant.
  2. Open-drain Mode: To drive “1”, Controller Link turn-off the output-enable, and external (required) pull-up will pull the pin up to 1.8 V, which is compatible with WLAN voltage requirement.