AK7714 Datasheet, PDF (45/48 Pages) Asahi Kasei Microsystems – 20-Bit Audio Codec with DSP and Delay RAM

[ASAHI KASEI]
[AK7714]
The analog source voltage to the AK7714 is +5 V. Voltage of AVDD + 0.3 V or more, voltage of AVSS - 0.3 V or less,
and current of 10 mA or more must not be applied to analog input pins (AINL and AINR). Excessive current will damage
the internal protection circuit and will cause latch-up, thereby damaging the IC. Accordingly, if the surrounding analog
circuit voltage is ±15 V, the analog input pins must be protected from signals with the absolute maximum rating or more.
Fig. 1 Example of input buffer circuit (differential input)
Fig. 2 Example of input buffer circuit (single end input)
An analog signal can be applied to the AK7714 is single end mode. In this case, apply the analog signal (the full scale
is 4.0 Vpp when the internal reference voltage is used) to the AIN-input, and bias to the AIN+input. However, use of a
low saturated operational amplifier is recommended if the operational amplifier is driven by the 5-volt power supply. The
electrolytic capacitor connected to AIN+ is effective for reducing the second harmomics.
(See Fig. 2.)
4) Analog output
Analog output is single-ended, and the output range is 2.95Vpp (typical) with respect to VCOM voltage. The out-of-
band noise (shaping noise) produced by the built-in ∆ ∑ modulator is reduced by the built-in switched capacitor filter
(SCF) and continuous filter (CTF). Therefore, it is not necessary to add an external filter for normal application. The
input code format is given in terms of 2's complements with the positive full-scale output for the 3FFFFH(@ 20 bit) input
code, and the negative full-scale output for the 80000H (@ 20 bit) input code. VCOM voltage is output as an ideal value
for 00000H(@ 20 bit) input code.
5) Connection to digital circuit
To minimize the noise resulting from the digital circuit, connect CMOS logic to the digital output. The applicable logic
family includes the 4000B, 74HC, 74AC, 74ACT and 74HCT series.
M0018-E-00
- 45 -
‘98/07