LC786821E Datasheet, PDF (16/35 Pages) ON Semiconductor – Compressed Audio Signal Processor IC

LC786821E
Power-ON/Reset Control
- Notes on Power-On
(1) Regarding Reset Pin
To stabilize the operation condition of the internal FlashROM, RESB pin must need to be “L”.
If RESB pin is “H” at the Power-On, operation condition of the Flash memory becomes unstable and the operation
of this LSI becomes unstable. In this case, Reset by RESET pin control does not return to the normal state, RESB
pin must be “L” at the Power-On.
(2) Regarding Volume Out
Volume output becomes unknown state when Power-On, external circuit must care by muting/etc. from external
circuit.
- Power-On/Power-Down/Reset Timing
3.3V Power supply
VDD1
vBOT
0V
tPWD
3.3V Power supply
VDD1
RESB Pin
tRESW1
At the Power-On
tRESW2
Normal Operation
(Clock oscillation stable)
Parameter
Symbol
Min
Typ
Power-On rise time
tPWD
10
Power-Down fall time
vBOT
0
Reset period (at Power-On)
tRESW1
20
Reset period (When normal
operation) (*1)
tRESW2
1
*1: Reset period at normal operation is the period that clock is stablely oscillating.
Need to care about clock stable time when making clock OFF by commands.
Max
0.2
Unit
ms
V
ms
ms
- Regarding RESB pin control and internal Flash memory
As stated above, reset of the operation state of the flash memory in this LSI cannot be controlled by only RESB pin,
and needs Poer-On-Reset. Therefore, when flash memory goes to runaway state during the power is on, Power-On-
Reset must be done. In this case, users must power off the LSI and execute the Power-On-Reset.
On the other hand, reset control by RESB pin is effective to the circuit other than the flash memory. By making
RESB pin to “L” for the time period stated above with the stable clock, the circuit except flash memory is initialized.
Also, by this operation, flash memory becomes stand-by state and states of the memory cells are kept.
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