AK2308LV_05 Datasheet, PDF (19/31 Pages) Asahi Kasei Microsystems – SPEECH CODEC for Digital Key telephone

ASAHI KASEI
[AK2308LV]
4. Power on Reset
Power on Reset
AK2308LV automatically generates the internal reset pulse wh ich resets all the circuit that is necessary to start the
initialization after the power on reset. The CPU registers are set to the default value.
After the internal reset pulse is generated, CODEC starts the initialization procedure by being fed FS signa l, and it takes
150ms(typ.), 330ms(max) to complete the initialization after the detection of power on.
Power up slope to enable the Power-on Reset
When the power-up slope is no longer than 50ms(=5tau:tau is time constant), Power On Reset works normally.
When the slope is longer than 50ms, Power On Reset may not be activated and no internal registers are initialized. In
this case all registers must be written through CPU interface.
NOTE) For the stable operation after power up, we recommend to write all register value through CPU interface in any
case after the power up.
Recommended start up procedure
The following start up procedure is recommended when AK2308LV is going to power up.
Power up
Wait 200ms
*In case of VDD rising time
=50ms(=5tau)
- FS=”L”
- BCLK=”L”
During this stage, FS and BCLK must be tied to
“L” not to receive or transmit the data from/to the
external devices.
Write data to the internal
register through serial I/F
- Write data to the internal register
before CODEC starts working.
Supply FS and BCLK
Wait 250ms (min:130ms)
CODEC starts working
- CODEC Initialization starts.
- CODEC Initialization complete.
MS0227-E-01
19
2005/12