AK5730 Datasheet, PDF (30/50 Pages) Asahi Kasei Microsystems – 4-Channel Differential Audio ADC for Line & Mic Inputs

[AK5730]
(C) Booster Input mode (LIN*1-0 bits = “10”)
The booster inputs are directly driven by a standard automotive power amp, either by a class AB, a class SB (I) or even by
a class D amplifier. The connection is made in a fully balanced manner. In case of using a class SB (I) amplifier, the input
voltage may contain common mode signal inside the audio bandwidth due to switching from bridge to single ended mode
and vice versa. Booster inputs may share a Quad-ADC with any other input type (line, phone and microphone).
Parameter
Input voltage typ.
Input voltage max.
Specification
Remarks
10.0V RMS
@ battery voltage <14.4V
11.7V RMS
@ battery voltage =16.5V
Table 13 Specification (Booster Input mode)
Power Amp
VBAT
AMP
R1
R3
R2
Mic
Bias,
CP
IN*P
IN*N
Figure 29. Booster Input mode (IN*P/N pins)
Diagnostic functions are performed by the external amplifier. A simple check can be made, whether the input is connected
or not. Input is connected to amp output: VDC+ = VDC- = VBAT / 2. Refer to Note 14 and Figure 30 about Fault
Conditions. The “Input open State ((R2+R3)/(R1+R2+R3) * Vbias) and (R2/(R1+R2+R3) * Vbias)” are detected based
on SAR threshold B and C (THB12-01 bits, THC12-01 bits). The threshold B and C are 12bit straight binary codes, which
the full scale is 11V (Typ.).
Fault Conditions
Conditions
Positive input open
(R2+R3)/(R1+R2+R3) * Vbias –Vth ≤ VDC+ ≤ (R2+R3)/(R1+R2+R3) * Vbias +Vth
Negative input open
R2/(R1+R2+R3) * Vbias – Vth ≤ VDC- ≤ R2/(R1+R2+R3) * Vbias + Vth
Note. Positive/Negative input open conditions are statuses when there is no input signal and DC voltage is not supplied by
the input signal.
Table 14 Fault Conditions (Booster Input mode)
Power Amp
Vbias
VBAT
AMP
R1
R3
R2
Mic
Bias,
CP
INM*P
INM*N
Figure 30. Booster Input Mode (INM*P/N pins)
Rev 0.8
- 30 -
2013/06