HCS362-I Datasheet, PDF (7/38 Pages) Microchip Technology – KEELOQ Code Hopping Encoder

FIGURE 2-4: HCS362 VLOW DETECTOR
(TYPICAL)
2.7
2.5
2.3
2.1
1.9
1.7
1.5
-40 -25 -10 5
20 35 50 65 80
Temperature (°C)
VDD Legend
x = 000
s = 001
v = 010
" = 011
FIGURE 2-5: HCS362 VLOW DETECTOR
(TYPICAL)
5.5
5.3
5.1
4.9
4.7
4.5
4.3
4.1
3.9
3.7
3.5
-40 -25 -10 5 20 35 50 65 80
Temperature (°C)
VDD Legend
x = 000
s = 001
v = 010
" = 011
The output of the low voltage detector is transmitted in
each code word, so the decoder can give an indication
to the user that the transmitter battery is low. Operation
of the LED changes as well to further indicate that the
battery is low and needs replacing.
HCS362
2.2 Dual Encoder Operation
The HCS362 contains two crypt keys (possibly derived
from two different Manufacturer’s Codes), but only one
Serial Number, one set of Discrimination bits, one 16-
bit Synchronization Counter and a single 60-bit Seed
value. For this reason the HCS362 can be used as an
encoder in multiple (two) applications as far as they
share the same configuration: transmission format,
baud rate, header and guard settings. The SHIFT input
pin (multiplexed with the LED output) is used to select
between the two crypt keys.
A logic 1 on the SHIFT input pin selects the first crypt
key.
A logic 0 on the SHIFT input pin will select the second
crypt key.
© 2002 Microchip Technology Inc.
Preliminary
DS40189D-page 7