HCS320 Datasheet, PDF (21/32 Pages) Microchip Technology – KEELOQ Code Hopping Encoder

HCS320
FIGURE 8-2:
POWER-UP AND TRANSMIT TIMING
Button Press
Detect
TBP
TTD
Multiple Code Word Transmission
TDB
PWM
Output
Code
Word
1
Code
Word
2
TTO
Code
Word
3
Code
Word
4
Code
Word
n
Button
Input
Sn
FIGURE 8-3:
POWER-UP AND TRANSMIT TIMING REQUIREMENTS
VDD = +3.5 to13.0V
Commercial (C): Tamb = 0°C to +70°C
Industrial (I): Tamb = -40°C to +85°C
Parameter
Symbol
Min
Max
Unit
Remarks
Time to second button press
TBP
10 + Code 27 + Code
ms
Word Time Word Time
(Note 1)
Transmit delay from button detect
TTD
10
27
ms
Debounce delay
TDB
6
15
ms
Auto-shutoff time-out period
TTO
22
77
s
(Note 2)
Note 1: TBP is the time in which a second button can be pressed without completion of the first code word and the
intention was to press the combination of buttons.
2: The Auto-shutoff time-out period is not tested.
FIGURE 8-4:
CODE WORD FORMAT
TE TE TE
LOGIC ‘0’
LOGIC ‘1’
Bit Period
TBP
50% Duty Cycle
Preamble
TP
Header
TH
Encrypted Portion
of Transmission
THOP
Fixed Portion of
Transmission
TFIX
Guard
Time
TG
© 2001 Microchip Technology Inc.
DS41097C-page 21