MC145436
DTMF decoder (Motorola)
DV goes high when a tone is detected on IN (-32..-2dB).
XEN is oscillator enable (pull high, and connect a Xtal // 1M resistor to
X1 and X2).  If XEN is low, ATB can be used to connect multiple chips
together.  GT determines the guard time, 0=short 1=long.

      +----------+
   D1 |1  +--+ 14| D2
   D0 |2       13| D3
   OE |3       12| DV
  VCC |4  MC14 11| ATB
   GT |5  5436 10| X1
  XEN |6        9| X2
   IN |7        8| GND
      +----------+

[This information is part of the GIICM]