SAF1760BE/V1,557 NXP Semiconductors, SAF1760BE/V1,557 Datasheet - Page 98

• Manufacturer Part Number: SAF1760BE/V1,557
• Manufacturer: NXP Semiconductors

Specifications of SAF1760BE/V1,557

• Lead Free Status / Rohs Status: Compliant

NXP Semiconductors
17. Appendix
SAF1760_1
Product data sheet
17.1.3.1 Software retry mechanism
17.1.1 Problem description
17.1.2 Implication
17.1.3 Workaround
17.1 Errata added on 2009-04-23
For further information on temperature profiles, refer to Application Note AN10365
“Surface mount reflow soldering description” .
When the SAF1760 is programmed to perform infinite retries on Not Acknowledged
(NAK) IN tokens, the SAF1760 does not generate the retry IN tokens on its own.
According to the SAF1760 data sheet, if register RL is programmed as zero, NakCnt is
ignored. This means that irrespective of the value of NakCnt, the SAF1760 must retry
indefinitely because there is no NakCnt to limit the number of retries for a NAK IN token.
The SAF1760 hardware, however, does not retry the NAK IN token.
After an IN token is seen on the USB bus and is NAK-ed by the downstream device, the
SAF1760 will not perform any automatic retry. Instead an interrupt will be generated in the
ATL_IRQ bit of the HcInterrupt register (310h), and the software must refresh the IN token
Proprietary Transfer Descriptor (PTD) for the retry to occur on the USB bus. This causes
the software to constantly service this retry, unless the application instructs it to stop
retrying.
Set program register RL = 1111b and NakCnt = 1111b. In this case, interrupt will be
generated when NakCnt reaches zero and the software has to reload the transfer
descriptor.
Fig 23. Temperature profiles for large and small components
temperature
MSL: Moisture Sensitivity Level
Rev. 01 — 9 November 2009
= minimum soldering temperature
maximum peak temperature
minimum peak temperature
= MSL limit, damage level
Embedded Hi-Speed USB host controller
temperature
peak
SAF1760
© NXP B.V. 2009. All rights reserved.
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