AMIS-52150 Datasheet, PDF (13/21 Pages) AMI SEMICONDUCTOR – Low-Power Transceiver with Clock and Data Recovery

AMIS−52150
Quick Start
There are two oscillators in the AMIS−52150, a low
power 10 kHz RC oscillator and a crystal oscillator,
respectively.
The RC oscillator is used to keep the AMIS−52150
running in the ultra-low power mode. This oscillator is used
to generate the clock signals for the Sniff Mode timers as
well as the wake-up timers. Figure 10 shows a block
diagram of the clocks in the AMIS−52150. The crystal
oscillator provides the reference frequency which is used to
generate the RF frequencies for transmission and receiving
of data. It is also the reference for all the timing functions in
the AMIS−52150. The RC oscillator is in turn used to
produce a “kicker” signal when the Quick Start function of
the crystal oscillator is needed.
Figure 10. Internal Clocks
A “kicker” circuit stimulates the crystal oscillator circuit
with oscillations close to the final frequency. This
significantly reduces the time it takes for the oscillator to
reach and lock to the final frequency. The Quick Start
function is necessary for operation in Sniff Mode. Table 20
lists the Quick Start control registers.
Table 20. QUICK START CONTROL REGISTERS
Register (HEX)
Name
Bits
States
0x03
Kick Trim
All
0x0e
Kick Config1
4
0
1
Kick Config2
5
0
1
Comments
Trim the Internal RC OSC to Form a Kick-start to the XTAL Oscillator
Common Mode Clamp Disabled (Startup)
Common Mode Clamp Enabled (Normal)
Normal Operation
Continuous Kick On
Data Detection
The RSSI circuit creates an analog voltage waveform
(18 mV/dB) that follows the signal strength of the RF signal.
The data slice circuit then samples that waveform to create
the digitized data. The slice circuit in the AMIS−52150 can
be programmed to operate in one of three modes; DAC
mode, Average mode or Peak mode. The DAC mode
compares a fixed slice threshold value to the level in the slice
output. The digital data state is determined by the level of the
slice output being above or below that fixed threshold.
Figure 11 shows a typical waveform for the DAC mode,
while Table 21 shows the control registers for the auto slice
modes.
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