L9963T datasheet(14/45 Pages) STMICROELECTRONICS

14 / 45 page

•

When NSLAVE = 1 (Master configuration), this pin acts as digital input for the selection of CPHA (Clock

PHAse). It is latched during Trimming & Config Latch and should be therefore either shorted to GND or to

VDD:

–

CPHA = 0 (shorted to GND) implies that the SDI signal will be sampled upon the first SCK edge after

NCS assertion.

–

CPHA = 1 (shorted to VDD) implies that the SDI signal will be sampled upon the second SCK edge

after NCS assertion.

The internal pull-up is enabled when L9963T is in Trimming & Config Latch and is kept enabled in Normal state

in order to allow a correct driving of the pin by the open-drain output of the MCU. Moreover, in case of pin loss,

the pull-up guarantees a limp home operation where the transmitter is always enabled. To guarantee standby

consumption requirements, the pull-up is disabled while in Stand-by state.

Figure 8. TXEN/CPHA pin structure

3.2.1.7

TXAMP

TXAMP pin can be used to switch between the two possible ISOline TX amplitude configurations:

•

TXAMP = 0 selects low TX amplitude (RDIFF_ISO_OUTL)

•

TXAMP = 1 selects high TX amplitude (RDIFF_ISO_OUTH)

TXAMP sampling depends on the device state and configuration:

Table 10. TXAMP sampling strategy

L9963T

state

L9963T

configuration

TXAMP sampling

Note

Normal

state

Slave (NSLAVE =

The TXAMP pin is latched upon NCS assertion. Therefore, it must

be stable at least TTXAMP_DEGLITCH + TTXAMP_SETUP before NCS

assertion. Moreover, TXAMP must be kept stable TTXAMP_HOLD

after NCS assertion in order to fulfil hold time constraints.

The new amplitude setting is applied to the TX interface after the

SPI frame has been completely transmitted over the isolated SPI

interface. This allows Managing ISOFREQ And TXAMP Pins For

Communicating With L9963.

In case several SPI

frames are being

pushed into the TX

queue, the setting

applied depends

on the last one

latched (no pipelining

supported).

L9963T

Pin configuration

DS13590 - Rev 4

page 14/45

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