L9663 Datasheet, PDF (25/104 Pages) STMicroelectronics – PSI5 Transceiver IC

L9663
3
Satellite interface
Satellite interface
3.1
Receiver with digital sampling and filtering
This module has the following features:
 The output current signal is mirrored and converted to the digital domain
 Automatic synchronization on entire PSI5 frames
 Fast DAC digital conversion of sensed currents with digital filtering
 Static DC current set point tracking of PSI5 quiescent current.
 Tracking of modulated PSI5 current signal
The quiescent current tracking can be configured to work in two ways (reg. ADVSET1,
ADVSET3, bits FREEZE_DIS): continuous mode tracking or tracking between consecutive
frames till the first edge of a new frame is recognized. In the second case, the quiescent
current is frozen till the end of the frame.
To recognize the PSI5 current signal level the receiver compares the digitally converted and
filtered current with a threshold. This threshold can be fixed or dynamic, depending on the
configuration selected by SPI (reg. ADVSET).
In fixed threshold mode the user must program the right delta current threshold, according
to the application requirements. The threshold is obtained as tracked quiescent current plus
the programmed threshold.
In dynamic threshold mode, the threshold is dynamically adapted considering the PSI5
current input signal.
For detailed explanation on all the possible configurations refer to ADVSET registers
section.
Depending on the selected configuration, the threshold for the sensor signal can be
permanently tracked, separately for each PSI5 interface. The IC is designed to compensate
erratic changes of the quiescent current in the bus according to PSI5 standard
requirements.
The v2.x standard low power mode is not supported with dynamic threshold mode.
Micro cuts up to 10μs do not affect the DC current tracking in a way that more than one
frame will be lost.
The PSI5 Receiver is designed to operate at:
 83.3 Kbps typical (slow mode)
 125 Kbps typical (standard mode)
 189 Kbps typical (fast mode).
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