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AR# 64099

Zynq-7000 AP SoC, Where I can find the ScanDisk eMMC pull-up recommendation?

Description

Where I can find the ScanDisk eMMC (SKU SDIN7DP2-4G) pull-up recommendation?

Solution

The SKU SDIN7DP2-4G is an eMMC 4.51, so you will need to refer to the JEDEC spec JESD84-B451 for all information not described in the Scandisk's user manual.
 
This public document can be downloaded free-of-charge upon registration at the following link: www.jedec.org/standards-documents/results/jesd84-b451
 

The Data-0 has no internal pull-ups into the device.

Data 1-7 have internal pull-ups, which are disconnected after power-up for the active lines, when a specific transfer mode is selected.

In the case of 4-bit mode, only the active signals are disconnected from the internal pull-up.

As Data0 is the only data-line at start-up which is active, it has no pull-up.

It will remain active during any transfer mode selected.


This information can be checked in the JEDEC spec, Chapter 5.3, Device Overview.
 
As the Data-pins are bidirectional and basically have open-drain buffers, external pull-ups are required on DAT 0-7 regardless of whether they have internal pull-ups or not.

This is required so that the bus is not left floating during non-active phases.
 
The guidelines for the external pull-up are still in the JEDEC spec (Paragraph 10.3.4, Bus signal line load).
AR# 64099
Date Created 03/30/2015
Last Updated 04/17/2015
Status Active
Type General Article
Devices
  • Zynq-7000