U2270B_08 Datasheet, PDF (8/18 Pages) ATMEL Corporation – Read/Write Base Station

Figure 3-7. Equivalent Circuit of Pin HIPASS
R
+
-
LPF
R
V_Ref
R
R
R_i
HIPASS
C_HP
Schmitt
trigger
3.6 Schmitt Trigger
The signal is processed by a Schmitt trigger to suppress possible noise and to make the signal
microcontroller-compatible. The hysteresis level is 100 mV symmetrically to the DC operation
point. The open-collector output is enabled by a low level at OE (pin 3).
Figure 3-8. Equivalent Circuit of Pin OE
7 µA
OE
8 U2270B
4684E–RFID–02/08