Using the AT89RFD-08 Board
AT89RFD-08 Hardware User Guide
2-27
4382E–MP3–05/06
Example with Fc=100 Hz, PA Gain = +5 dB => Cin = 27 nF
For low frequency noise rejection, internal mechanism is a full differential mode, and
decoupling with common mode (capacitor CBP).
14. What are the PA impedance in power-off?
n Between PAINP and HPN (or LPHN): 165 K ohms.
n Between PAINN and HPP (or LPHN): 165 K ohms.
n Between HPP and HPN: 10 K ohms.
n Between HPP and LPHN: 10 K ohms.
15. What will be the AT8xC51SND2C power supply during USB mass storage
mode?
The AT8xC51SND2C power supply (VDD, UVDD, PVDD) shall be > 3 V to comply USB
specification (output level voltage on D+/D-).
If USB certification is not required, it is possible to have 2.8V for VDD, UVDD, PVDD,
but the D+ pull-up (controlled by PNP transistor) shall be connected to a voltage > 3V.
Note:
Refer to USB chapter 7 http://www.usb.org/developers/docs
8 46.5
K
5 60
K
2
72 K
-1 87
K
-4
100.5 K
-7
114 K
-10
126 K
-13
135 K
-16
142.5 K
-19
148.5 K
-22
153 K
PA Gain (dB)
PA Zin (ohm)