ak5385b AKM Semiconductor, Inc., ak5385b Datasheet - Page 18

• Manufacturer Part Number: ak5385b
• Description: 24bit 192khz ?? Adc
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
[AK5385B]
1. Grounding and Power Supply Decoupling
The AK5385B requires careful attention to power supply and grounding arrangements. Alternatively if AVDD and
DVDD are supplied separately, the power up sequence is not critical. AVSS, BVSS and DVSS of the AK5385B must be
connected to analog ground plane. System analog ground and digital ground should be connected together near to
where the supplies are brought onto the printed circuit board. Decoupling capacitors should be as near to the AK5385B as
possible, with the small value ceramic capacitor being the nearest.
2. Voltage Reference Inputs
The reference voltage for A/D converter is supplied from VREFL/R pins at AVSS reference. AVSS pin is connected to
analog ground and an electrolytic capacitor over 10µF parallel with a 0.1µF ceramic capacitor between the VREFL/R pins
and the AVSS pin eliminate the effects of high frequency noise. Especially, a ceramic capacitor should be as near to the
pins as possible. And all digital signals, especially clocks, should be kept away from the VREFL/R pins in order to avoid
unwanted coupling into the AK5385B. No load current may be taken from the VREFL/R pins.
VCOM is a signal ground of this chip. An electrolytic capacitor 0.22µF attached to VCOM pin eliminates the effects of
high frequency noise. No load current may be drawn from the VCOM pin. All signals, especially clocks, should be kept
away from the VCOM pin in order to avoid unwanted coupling into the AK5385B.
3. Analog Inputs
Analog signal is differentially input into the modulator via the LIN+ (RIN+) and the LIN− (RIN−) pins. The input voltage
is the difference between the LIN+ (RIN+) and LIN− (RIN−) pins. The full scale of each pin is nominally ±2.9Vpp(typ).
The AK5385B can accept input voltages from AVSS to AVDD. The ADC output data format is 2’s complement. The
internal HPF removes the DC offset.
The AK5385B samples the analog inputs at 128fs (6.144MHz@fs=48kHz, Normal Speed Mode). The digital filter rejects
noise above the stop band except for multiples of 128fs. The AK5385B includes an anti-aliasing filter (RC filter) to
attenuate a noise around 128fs.
The AK5385B accepts +5V supply voltage. Any voltage which exceeds the upper limit of AVDD+0.3V and lower limit
of AVSS−0.3V and any current beyond 10mA for the analog input pins (LIN+/−, RIN+/−) should be avoided. Excessive
currents to the input pins may damage the device. Hence input pins must be protected from signals at or beyond these
limits. Use caution specially in case of using ±15V in other analog circuits.
MS0406-E-00
2005/08
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