MCP2030 Microchip Technology Inc., MCP2030 Datasheet - Page 36

• Manufacturer Part Number: MCP2030
• Description: Three-channel Analog Front-end Device
• Manufacturer: Microchip Technology Inc.

MCP2030
5.15
Configurable Output Enable Filter
The purpose of this filter is to enable the LFDATA out-
put and wake the external microcontroller only after
receiving a specific sequence of pulses on the LC input
pins. Therefore, it prevents waking up the external
microcontroller due to noise or unwanted input signals.
The circuit compares the timing of the demodulated
header waveform with a pre-defined value, and
enables the demodulated LFDATA output when a
match occurs.
The output enable filter consists of a high (T
) and
OEH
low duration (T
) of a pulse immediately after the
OEL
AGC settling gap time. The selection of high and low
times further implies a max period time. The output
enable high and low times are determined by SPI
programming. Figure 5-3 and Figure 5-4 show the
output enable filter waveforms.
There should be no missing cycles during T
.
OEH
Missing cycles may result in failing the output enable
condition.
Start bit
Required Output Enable Sequence
Data Packet
T
STAB
(T
+ T
)
AGC
PAGC
Demodulator
T
GAP
Output
t
T
t
T
OEH
OEL
Device Wake-up
AGC
and AGC Stabilization
Gap Pulse
LFDATA output is enabled
t
T
OET
on this rising edge
FIGURE 5-3:
Output Enable Filter Timing.
© 2005 Microchip Technology Inc.
DS21981A-page 36