March 2006 Rev 1 1/4
L9638D
Errata Sheet
Potential RxD lock-up upon LIN wake-up
during sleep mode transition
1 Silicon identification
This document refers only to L9638D device.
2 Reference specification
Limitations in this document are with reference to the L9638D datasheet rev 4 (October 2004).
3 Silicon limitations
3.1 Potential RxD lock-up upon LIN walk-up during sleep mode
transition
A lock-up of the RxD signal path can potentially happen, when a falling edge on the LIN bus
occurs during the transition from NORMAL to SLEEP mode.
The transition from NORMAL to SLEEP mode is initiated by the application with a falling
edge on EN. With this event an internal timer is started to qualify a valid low level on EN.
At the end of this filter period (tGTS, typically 40µs) the sleep mode is entered and the INH
output signal is switching to low level.
This transition to SLEEP mode however does not occur when a walk-up event is detected
before the timer expired (tGTS).
The lock-up condition may occur: IF a falling edge on the LIN bus occurs WITHIN the
critical window before INH goes low. The maximum duration of the critical window is
1µs. To exit the lock-up state the power supply of the device must be switched off.
The timing of the lock-up condition is shown in the diagram below.
Figure 1. Timing of the lock-up condition
The critical window starts 1µs before INH
goes down (signaling that L9638D is in
SLEEP mode).
A falling edge on the LIN bus during this
window may lock-up the RxD signal in a tri-
state mode.
EN
LIN
tGTS = 40..100µs
LIN
INH
INH
Critical Window = 1µs
EN
LIN
tGTS = 40..100µs
LIN
INH
INH
Critical Window = 1µs
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Workaround L9638D - Errata Sheet
2/4
4 Workaround
ST recommends to do not use the SLEEP mode of the L9638D if a falling edge on the LIN
can occur during the transition from NORMAL to SLEEP.
A falling edge may be caused either by a frame, a wake-up signal or a perturbation on the
LIN bus.
Revision history L9638D - Errata Sheet
3/4
5 Revision history
Table 1. Document revision history
Date Revision Changes
21-Mar-2006 1Initial release.
L9638D - Errata Sheet
4/4
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