AK5572 Datasheet, PDF (64/68 Pages) Asahi Kasei Microsystems – 2-Channel Differential 32-bit ADC

[AK5572]
1. Grounding and Power Supply Decoupling
The AK5572 requires careful attention to power supply and grounding arrangements. Normally AVDD
and TVDD are supplied from analog supply of the system. The power-up sequence between AVDD1 and
TVDD are not critical when AVDD and TVDD are supplied separately. DVSS and AVSS must be
connected to the same analog ground plane. System analog ground and digital ground should be
wired separately and connected together as close as possible to where the supplies are brought onto the
printed circuit board. Decoupling capacitors for high frequency should be placed as near as possible to
the supply pin.
2. Reference Voltage
The differential voltage between the VREFH1 pin and the VREFL1 pin is the common voltage of A/D
conversion. The VREFL1 pins are normally connected to AVSS. In order to remove a high frequency
noise, connect a 20 Ω resistor between the VREFH1 pins and analog 5 V supply, and connect a 0.1 μF
ceramic capacitor in parallel with an 100 μF electrolytic capacitor between the VREFH1 pin and the
VREFL1 pin. Especially the ceramic capacitor should be connected as close as possible to the pin. All
digital signals, especially clocks, should be kept away from the VREFH1 and VREFL1 pins in order to
avoid unwanted noise coupling into the AK5572.
3. Analog Inputs
The Analog input signal is differentially supplied into the modulator via the AINn+ and the AINn- pins (n=
1-2). The input voltage is the difference between the ALINn+ and ALINn- pins (n= 1-2). The full scale
signal on each pin is nominally ±2.8 V (typ). A voltage from AVSS to AVDD can be input to the AK5572.
The output code format is two’s complement. The internal HPF removes DC offset (including DC offset
by the ADC itself).
The AK5572 requires a +5 V analog supply voltage. Any voltage which exceeds the upper limit of
AVDD+0.3 V and lower limit of AVSS0.3 V and any current beyond 10 mA for the analog input pins
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 especially when using ±15 V for other
analog circuits in the system.
015016766-E-00
- 64 -
2015/12