stled325 STMicroelectronics, stled325 Datasheet - Page 17

• Manufacturer Part Number: stled325
• Description: I?c Interfaced, Advanced Led Controller/driver With Keyscan, Standby Power Management And Real Time Clock Rtc
• Manufacturer: STMicroelectronics

STLED325
3.10.2
Entering standby mode
The STLED325 controls the power to the main board using the STBY pin. During normal
operation, the STBY pin is a low level which externally controls a Power MOS switch to
enable power to the main board. The STLED325 asserts the STBY pin to a high when any
one of the following conditions occur:
Figure 6.
– Processor fails to respond by enabling the READY pin within 10s upon first power-up
– Guard timer counts down to 0s
– Processor makes the READY pin to low (can happen in various conditions such as
– Guard timer can be kept on during normal condition when READY is high (depending
– In this condition, the guard timer can be disabled or enabled. If the guard timer is
– It is advisable not to enable the guard timer during normal operation.
(cold boot up)
user presses STBY key on front panel, STBY key on remote control, etc).
on the user).
enabled, the timer needs to be cleared before the programmed count of the timer is
reached. If the programmed count is reached, the STBY will be asserted.
Power down condition (normal behavior)
2a) Power-down condition (normal behavior )
2b) Power-down condition (abnormal behavior of processor )
READY
MUTE
STBY
READY
Guard timer is not required here
MUTE
STBY
In this case the READY remains high and as long as
READY is high, the MUTE is low and STBY is low.
Doc ID 17576 Rev 1
2 us
READY continues to remain high
Functional description
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