HCS473T-I/SN Microchip Technology, HCS473T-I/SN Datasheet - Page 18

• Manufacturer Part Number: HCS473T-I/SN
• Description: IC KEELOQ 3AXIS TRANSCODER 8SOIC
• Manufacturer: Microchip Technology
• Series: KEELOQ®r
• Type: Code Hopping Encoder and Transponderr

Specifications of HCS473T-I/SN

• Applications: Access Control Systems
• Mounting Type: Surface Mount
• Package / Case: *
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification

HCS473
FIGURE 3-6:
3.1.4.9
SDBT selects which switch input(s) activate a seed
transmission. Seed transmissions are disabled by
clearing all 4 bits. If a button combination is pressed
that matches the 4-bit SDBT value, a seed code word
is transmitted as configured by the SDTM, SDLM and
SDMD options (see following sections).
The binary bit order is S3-S2-S1-S0. For example, if
you want the combination of S2 and S0 to activate a
seed transmission, use SDBT=0101
SDBT options:
• Seed is transmitted when SDBT flags match the
• SDBT = 0000
3.1.4.10
The time before seed option selects the delay from
device activation until the seed code words are trans-
mitted. If the delay is not zero, the HCS473 transmits
hopping code words until the selected time, then trans-
mits seed code words.
As code words are always completed, the seed code
word begins the first code word after the specified time.
SDTM options:
• 0s - seed code words begin immediately
• 0.8s
• 1.6s
• 3.2s
DS40035C-page 16
button input flags
Note:
ASK:
FSK:
Configuring S3/RFEN as RFEN (see
Section 3.1.4.8) prevents the use of S3 to
trigger a seed transmission.
SEED Button Code (SDBT)
Time Before Seed (SDTM)
S3/RFEN
S3/RFEN
SWITCH
2
DATA
DATA
disables seed capability.
ENCODER OPERATION: RF ENABLE/ASK/FSK OPTIONS
T
PU
2.
T
PLL
Code Word
Code Word
Preliminary
Code Word
Code Word
3.1.4.11
The limited seed option may be used to disable seed
transmission capability after a configurable number of
transmitter activations; limiting a transmitter’s ability to
be learned into a receiver. Specifically, seed transmis-
sions are disabled when the synchronization counter’s
LSB increments from 7Fh to 80h.
SDLM options:
• unlimited seed capability
• limited seed capability - counter value dependent
3.1.4.12
The Seed mode option selects between User and Pro-
duction seed modes. Production mode functions as a
special time before seed case (SDTM).
With Production mode enabled, a seed button code
activation triggers MTX hopping code words followed
by MTX seed code words. Production mode functional-
ity is disabled when the synchronization counter’s LSB
increments from 7Fh to 80h.
SDMD options:
• User
• Production
3.1.4.13
The timing of code word data modulated on the DATA
pin is referred to in multiples of a basic Timing Element
RFT
sent through a RF transmitter to the decoder or tran-
sponder reader.
RFT
(RFBSL) configuration option. RF
ject to the oscillator variation over temperature and
voltage.
RFBSL options:
• 100 µs RFT
• 200 µs RFT
• 400 µs RFT
• 800 µs RFT
E
E
. ‘RF’ T
may be selected using the RF Baud Rate Select
Code Word
Code Word
E
SEED Mode (SDMD)
RF Baud Rate Select (RFBSL)
E
E
E
E
because the DATA pin output is typically
Limited Seed (SDLM)
Code Word
Code Word
 2002 Microchip Technology Inc.
TE
accuracy is sub-