MCP2030-I/ST Microchip Technology, MCP2030-I/ST Datasheet - Page 39

• Manufacturer Part Number: MCP2030-I/ST
• Description: IC KEYLESS ENTRY AFE 14TSSOP
• Manufacturer: Microchip Technology

Specifications of MCP2030-I/ST

• Rf Type: ISM
• Frequency: 125kHz
• Features: 10kbps
• Package / Case: 14-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

TABLE 5-2:
5.17
Each channel can be individually enabled or disabled
by programming bits in Configuration Register 0<3:1>
(Register 5-1).
The purpose of having an option to disable a particular
channel is to minimize current draw by powering down
as much circuitry as possible, if the channel is not
needed for operation. The exact circuits disabled when
an input is disabled are amplifiers, detector, full-wave
rectifier, data slicer, and modulation FET. However, the
RF input limiter remains active to protect the silicon
from excessive antenna input voltages.
5.18
The circuit automatically amplifies input signal voltage
levels to an acceptable level for the data slicer. Fast
attack and slow release by nature, the AGC tracks the
carrier signal level and not the modulated data bits.
The AGC inherently tracks the strongest of the three
antenna input signals. The AGC requires an AGC
initialization time (T
The AGC will attempt to regulate a channel’s peak
signal voltage into the data slicer to a desired regulated
AGC voltage – reducing the input path’s gain as the
signal level attempts to increase above regulated AGC
voltage, and allowing full amplification on signal levels
below the regulated AGC voltage.
The AGC has two modes of operation:
1.
2.
Also, the AGC is frozen when the input signal envelope
is low. The AGC tracks only high envelope levels.
© 2005 Microchip Technology Inc.
(Config. Register 5)
During the AGC initialization time (T
AGC time constant is fast, allowing a reasonably
short acquisition time of the continuous input
signal.
After T
constant for data slicing.
AGCSIG<7>
Input Channels (Enable/Disable)
AGC Amplifier
0
1
AGC
, the AGC switches to a slower time
INPUT SENSITIVITY VS. MODULATED SIGNAL STRENGTH SETTING (AGCSIG <7>)
AGC
).
Option Disabled – Detect any input signal level (demodulated data and
carrier clock).
Option Enabled – No output until AGC Status = 1 (i.e., V
(demodulated data and carrier clock).
• Provides the best signal to noise ratio.
AGC
), the
Description
5.19
The AGC preserve feature is used to preserve the AGC
value during the AGC initialization time (T
apply the value to the data slicing circuit for the follow-
ing data streams instead of using a new tracking value.
This feature is useful to demodulate the input signal
correctly when the input has random amplitude varia-
tions at a given time period. This feature is enabled
when the device receives an AGC Preserve On com-
mand and disabled if it receives an AGC Preserve Off
command. Once the AGC Preserve On command is
received, the device acquires a new AGC value during
each AGC initialization time and preserves the value
until a Soft Reset or an AGC Preserve Off command is
issued. Therefore, it does not need to issue another
AGC Preserve On command. An AGC Preserve Off
command is needed to disable the AGC preserve
feature (see Section 5.31.2.5 “AGC Preserve On
Command” and Section 5.31.2.6 “AGC Preserve Off
Command” for AGC Preserve commands).
AGC Preserve
PEAK
20 mV
MCP2030
PP
)
DS21981A-page 39
Sensitivity
3.0 mV
(Typical)
20 mV
Input
AGC
PP
PP
) and