hcs362 Microchip Technology Inc., hcs362 Datasheet - Page 14

• Manufacturer Part Number: hcs362
• Description: Keeloq Code Hopping Encoder
• Manufacturer: Microchip Technology Inc.

HCS362
3.4
The S3/RFEN pin of the HCS362 can be configured to
function as an RF Enable output signal. This is selected
by the RF Enable Output (RFEN) configuration option.
When enabled, this pin will be driven HIGH before data
is transmitted through the DATA pin.
The RF Enable and DATA output are synchronized so
to interface with RF PLL circuits operating in ASK
mode. Figure 3-10 shows the startup sequence. The
RFEN signal will go LOW at the end of the last code
word, including the Guard time.
When the RF Enable output is selected, the S3 pin can
still be used as a button input. The debouncing logic will
be affected though, considerably reducing the respon-
siveness of the button input.
FIGURE 3-10: PLL INTERFACE
DS40189D-page 14
RF Enable and PLL Interface
S[3210]
RFEN
DATA
T
RFON
Button Press
T
TD
1st CODE WORD
Preliminary
Note:
2nd CODE WORD
When the RF Enable output feature is used
and a four (or more) buttons input configu-
ration is required, the use of a scheme sim-
ilar
recommended.
Button Release
to
Figure 2-1
Guard Time
2002 Microchip Technology Inc.
T
G
(scheme
C)
is