AK7712A-VT Datasheet, PDF (77/87 Pages) Asahi Kasei Microsystems – Built-in 20-bit ADC/DAC Sophisticated Audio DSP

ASAHI KASEI
[AK7712A-VT]
„ Reset Control
1) System Reset
During power-up, please reset by setting both PD and RST pin "L" to "H". The reset is cancelled at XTI "↑". Then,
the inside timing becomes to synchronize with LRCK"↑", and the inside LRCK becomes to action since 4LRCK
after, and DSP unit becomes to action.
2) Powerdown-Reset control
The reset is controlled with 2 pins of system reset(RST)and power down(PD). It is also able to control the state of
ADC/DAC by using PDAD/PDDA pins in support.
• The setting of "PD:L, RST:L" makes all the circuit reset and MOS resistance of quartz oscillator OFF. In this
state, by stopping XTI, BCLK and LRCK, power down state is realized(the leak is checked with this state at test).
At "PD:L, RST:L", since MOS resistance of quartz oscillator is also off, output from CLKO and XTO can not be
guaranteed.
"PD:L, RST:L" is used at power on, or at setting to power down state.
• If "PD:H, RST:L" is set, each register of DSP unit is reset(control register is not reset), and PRAM, DRAM and
OFRAM become write enable state. In that case, both of AD unit and DA unit become reset( power down)
state(when PDAD and PDDA are "L").
• The reset( power down) state is cancelled at first "↑" of XTI after setting RST to "H". In that case, DAC output is
done after 2Ts cycles, but ADC takes 516Ts cycles for initialize, then output data becomes "0". (Ts = 1/fs)
By PDAD/PDDA, the control of reset state(power down) for AD/DA unit can be separated to the control of reset
for DSP unit. Usually both of PDAD and PDDA are used with "L". But in the case that DSP is reset and
PRAM,DRAM and OFRAM are rewritten, not to make ADC and DAC power down state, please set PDAD and
PDDA to "H" after power on.
PD
RST
PDAD
PDDA
AD
DA
"L" "H" "H" "H" "H" "H"
"L" "L" "L" "L" "L" "H"
- "L" "L" "H" "H" -
- "L" "H" "L" "H" -
PD Õ Õ RUN RUN RUN
PD Õ RUN Õ RUN RUN
The format is shown in the table .
In the case of writing data to control
register, set PDAD and PDDA to "L".
To make the change of PDAD and
PDDA, set RST to "L".
(-: Don't care, PD: power down, RUN: run state, Õ: can not run)
0180-E-02
- 77 -
1997/12