HCS365 Datasheet, PDF (6/34 Pages) Microchip Technology – KEELOQ Code Hopping Encoder

HCS365
The HCS365 has an onboard nonvolatile EEPROM.
This EEPROM is used to store user programmable
data and the synchronization counter. The data is pro-
grammed at the time of production and includes the
security related information such as encoder keys,
serial numbers, discrimination values, and seed val-
ues. All the security related options are read protected.
The initial counter value is also programmed at the time
of production. From then on the device maintains the
counter itself. The HCS365 has built in redundancy for
protection and can recover from counter corruption.
The counter will not increment if the previous write was
corrupted by low voltage RESET or power failure dur-
ing TPLL. Instead, the counter will revert back to the
previous count and the HCS370 will attempt to correct
the bad bits. This will continue on every button press
until the voltage increases and the counter is success-
fully corrected.
FIGURE 2-1: TYPICAL CIRCUITS
VDD
B0
S0
VDD
B1
S1
LED
B2
S2
DATA
RFEN
VSS
RF PLL
DATA IN
ENABLE
Three buttons remote with PLL control
VDD
B4 B3 B2 B1 B0
S0
VDD
S1
LED
S2
DATA
S3
VSS
Tx out
Five buttons remote control (Note)
VDD
B1 B0
Tx2
Tx1
S0
S1
S2
SHIFT
VDD
LED
DATA
VSS
Tx out
Note:
DUAL Transmitter remote control
Up to 15 functions can be implemented by
pressing more than one button simulta-
neously or by using a suitable diode array.
DS41109D-page 6
Preliminary
© 2002 Microchip Technology Inc.