HCS473-I/SL Microchip Technology, HCS473-I/SL Datasheet - Page 10

• Manufacturer Part Number: HCS473-I/SL
• Description: IC KEELOQ 3AXIS TRANSCODR 14SOIC
• Manufacturer: Microchip Technology
• Series: KEELOQ®r
• Type: Code Hopping Encoder and Transponderr

Specifications of HCS473-I/SL

• Applications: Access Control Systems
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

HCS473
2.3.3
The transponder interface on the HCS473 consists of
the following:
• The internal transponder circuitry has separate
• LF input amplifier and envelope detector to detect
• Three sensitive transponder inputs with over-volt-
• Incoming LF energy rectification and regulation on
• 10V zener input protection from excessive
• LCCOM pin used to bias the transponder reso-
• LF antenna clamping transistors for inductive
• Damping transistors to increase LF communica-
The LCCOM pin functions to bias the LCX, LCY, and
LCZ AGC amplifier inputs. The amplifier gain control
sets the optimum level of amplification in respect to the
incoming signal strength. The signal then passes
through an envelope detector before interpretation in
the logic circuit.
A block diagram of the transponder circuit is shown in
Figure 2-8.
DS40035C-page 8
power supply (V
tions.
- The V
- The V
and shape the incoming low frequency excitation
signal.
age protection (LCX, LCY, LCZ).
the LCX input to supplement the supply voltage in
low-battery transponder instances.
antenna voltage resulting when proximate to very
strong magnetic fields.
nant circuits for best sensitivity.
responses back to the transponder reader. The
antenna ends are shorted together, ‘clamped’,
dissipating the oscillatory energy. The reader
detects this as a momentary load on its excitation
antenna.
tion reliability when using high Q-factor LC anten-
nae.
der circuitry and also outputs a regulated volt-
age if the LCX antenna input is receiving a
strong signal; transponder is placed in a
strong LF field.
to the transponder circuitry and must be con-
nected to the V
DDT
SST
TRANSPONDER INTERFACE
pin supplies the ground reference
pin supplies power to the transpon-
DDT
SS
) and ground (V
pin.
SST
) connec-
Preliminary
FIGURE 2-8:
2.3.4
The HCS473 has an on-board non-volatile EEPROM
which is used to store:
• configuration options
• 64 bits of user memory
• synchronization counter.
All options are programmable during production, but
many of the security related options are programmable
only during production and are further read protected.
The user area allows storage of general purpose infor-
mation and is accessible only through the transponder
communication path.
During every EEPROM write, the device ensures that
the internal programming voltage is at an acceptable
level prior to performing the EEPROM write.
- encryption keys
- serial number
- vehicle ID’s
- baud rates
- ... see Section 3.1.4 and Section 3.2.1
LCX
LCY
LCZ
LCCOM
INTERNAL EEPROM
Rectifier/
Regulator
HCS473 TRANSPONDER
CIRCUIT
 2002 Microchip Technology Inc.
Noise
Filter
V
Damp/Clamp
CCT
Signal In
Control