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AK5355 Datasheet, PDF (9/14 Pages) Asahi Kasei Microsystems – LOW POWER 16BIT ADC | |||
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ASAHI KASEI
[AK5355]
 Digital High Pass Filter
The AK5355 has a Digital High Pass Filter (HPF) to cancel DC-offset in both the ADC and input gain amplifier. The
cut-off frequency of the HPF is 3.4Hz at fs=44.1kHz. This cut-off frequency scales with the sampling frequency (fs).
 Input Gain Amplifier
The AK5355 includes an input gain amplifier. The gain can be changed to 0dB or +15dB by using the SEL pin. Input
impedance is 40k⦠typically.
 Power down
SEL pin
Gain
L
0dB
H
+15dB
Table 2. Input Gain Amplifier
The AK5355 is placed in the power-down mode by bringing PDN âLâ. The digital filter is also reset at the same time. This
reset should always be done after power-up. An analog initialization cycle starts after exiting the power-down mode. The
output data SDTO becomes available after 4128 cycles of LRCK clock. During initialization, the ADC digital data outputs
of both channels are forced to a 2âs complement â0â. The ADC outputs settle to the data corresponding to the input signals
at the end of initialization (Settling time equals the group delay time approximately).
PDN
Internal
State
A/D In
(Analog)
A/D Out
(Digital)
Clock In
MCLK,LRCK,BCLK
4128/fs(93.6ms@fs=44.1kHz)
Normal Operation
GD (1)
Power-down
Idle Noise
(2)
â0âdata
(3)
Initialize
Normal Operation
GD
â0âdata
Idle Noise
Notes:
(1) Digital output corresponding to the analog input is delayed by the Group Delay amount (GD).
(2) A/D output is â0â data in the power-down state.
(3) When the external clocks (MCLK, BCLK and LRCK) are stopped, the AK5355 should be placed in the power-
down state.
 System Reset
Figure 6. Power-down/up sequence example
The AK5355 should be reset once by bringing PDN âLâ upon power-up. The AK5355 is powered up and the internal
timing starts clocking by LRCK âââ after exiting reset and power down state by MCLK. The AK5355 is in the power-down
mode until MCLK and LRCK are input.
MS0113-E-00
-9-
2001/08
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