NXP Semiconductors
UM10858
PN7462 family HW user manual
UM10858
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© NXP B.V. 2018. All rights reserved.
User manual
COMPANY PUBLIC
Rev. 1.4 — 14 May 2018
314514
75 of 345
No.
Root cause description
3
Either RF level detector is activated as wakeup source and RF level detector is
not enabled or RF field is already present
4
Host Interface is selected as wakeup source and no PVDD is available
5
PVDD current limiter input has seen a 0
1
6
Negative-edge found on temperature error for temperature sensor 0,
considering temperature sensor 0 is enabled for wakeup
7
Negative-edge found on temperature error for temperature sensor 1,
considering temperature sensor 1 is enabled for wake-up
8
No host interface is selected
9
GPIO interrupt found
10
TVDD voltage has risen above 5 V
11
Card insertion or removal detected
12
Contact unart int_aux pin has given an interrupt
13
Contact deactivation is ongoing.
8.3.3 USB suspend mode
In this mode, only a few parts of USB are still active but not clocked. All clock sources
except LFO are stopped. PN7462 family will go into suspend state if there is no activity
on the USB bus for more than 3 ms.
8.3.3.1 Entering suspend mode
To enter suspend mode, the firmware needs to operate in an infinite while loop of:
1. Programming the suspend bit in the PCR_CTRL_REG
2. Wait for interrupt.
3. If the interrupt is SUSPEND_DEFAULTED then check for the standby prevention
reason (same register used for standby).
4. If any reason found, then cater to the prevention reason.
5. Now go back to step 1
If the interrupt is SUSPEND, then it means P7462 family has entered and come out of
suspend.
