HCS362-I Datasheet, PDF (6/38 Pages) Microchip Technology – KEELOQ Code Hopping Encoder

HCS362
FIGURE 2-2: I/O CIRCUITS
S0, S1, S2
Inputs
ESD
RS
VDD
PFET
S3 Input/
RFEN Output
ESD
RS
RFEN
VDD
PFET
NFET
DATA
DATA I/O
ESD
RDATA
LED output
SHIFT input
ESD
SHIFT
RL
RH
NFET
LEDL
NFET
LEDH
2.1 Architectural Overview
2.1.1 ONBOARD EEPROM
The HCS362 has an onboard non-volatile EEPROM,
which is used to store user programmable data. The
data can be programmed at the time of production and
include the security-related information such as
encoder keys, serial numbers, discrimination and seed
values. All the security related options are read
protected. The HCS362 has built in protection against
counter corruption. Before every EEPROM write, the
internal circuitry also ensures that the high voltage
required to write to the EEPROM is at an acceptable
level.
2.1.2 INTERNAL RC OSCILLATOR
The HCS362 has an onboard RC oscillator that con-
trols all the logic output timing characteristics. The
oscillator frequency varies within ±10% of the nominal
value (once calibrated over a voltage range of 2V –
3.5V or 3.5V – 6.3V). All the timing values specified in
this document are subject to the oscillator variation.
FIGURE 2-3: HCS362 NORMALIZED TE VS.
TEMPERATURE
1.10
1.08
TE
1.06
1.04
1.02 _TE
1.00
Typical
0.98
0.96
0.94
0.92
TE
0.90
-50-40 -30-20-10 0 10 20 30 40 50 6070 80 90
Temperature °C
VDD Legend
= 2.0V
= 3.0V
= 6.0V
Note: Values are for calibrated oscillator
2.1.3 LOW VOLTAGE DETECTOR
A low battery voltage detector onboard the HCS362
can indicate when the operating voltage drops below a
predetermined value. There are eight options available
depending on the VLOW[0..2] configuration options.
The options provided are:
000 - 2.0V
100 - 4.0V
001 - 2.1V
101 - 4.2V
010 - 2.2V
110 - 4.4V
011 - 2.3V
111 - 4.6V
DS40189D-page 6
Preliminary
© 2002 Microchip Technology Inc.