L9963T datasheet(9/45 Pages) STMICROELECTRONICS

9 / 45 page

Functional description

In the following paragraphs, the functionalities of the device are listed and described in detail.

3.1

Internal oscillators

L9963T features two internal oscillators for both main and stand-by functionalities.

Table 8. Device oscillators

Symbol

PARAMETER

MIN

TYP

MAX

UNIT

fMAIN_OSC

Internal MAIN Oscillator frequency

MHz

fSTBY_OSC

Internal STBY Oscillator frequency

kHz

3.2

Pin configuration

All device pins are hereby described.

3.2.1

Digital I/Os

In the following paragraph, the functionality of the Digital I/Os is explained.

BNE/CPOL, TXEN/CHPA are used as standard digital input (Schmitt trigger) or digital output (Output buffer)

configuration, depending on the configuration defined by digital NSLAVE pin.

DIS is used as standard digital input (Schmitt trigger) or digital output (Open Drain) configuration, depending on

the state the device is in. When it’s in STAND-BY state and a wake up comes from ISO line the DIS pin is driven

low by L9963T.

NSLAVE, ISOFREQ, TXAMP are used as standard digital input (Schmitt trigger) for the configuration of device.

3.2.1.1

SPI pin

SDO, SCK, SDI, NCS pins implement the SPI peripheral, whose configuration depends on the NSLAVE value

latched at first power up:

•

SDI is always configured as digital input. It is internally pulled down with RIN_PD in order to generate a 0x0

frame in case of pin loss (purpose is to lead to CRC violation in safety applications). Its buffer is enabled

only in Normal state.

•

SDO is always configured as digital output. Its buffer is enabled only if NCS is asserted. An external pull

up/pull down resistor defines the inactive level of the line.

•

SCK, NCS can be either configured as digital input (NSLAVE = 0, SPI Slave) or as digital output (NSLAVE =

1, SPI Master):

–

SCK pin is internally pulled down with RIN_PD in order to stabilize clock signal to logic ‘0’ in case of pin

loss.

–

NCS pin is internally pulled up with RIN_PU in order to disable SPI peripheral in case of pin loss.

–

When SCK and NCS are configured as digital input (NSLAVE = 0), the output buffers are permanently

disabled after Trimming & Config Latch is left.

–

When SCK and NCS are configured as digital output (NSLAVE = 1), the NCS inactive level is high, and

it is actively forced by the output buffer while no SPI communication is ongoing. The SCK inactive level

depends on the CPOL value latched in Trimming & Config Latch state, and it is actively forced by the

output buffer while no SPI communication is ongoing.

The selective enable/disable of the buffers helps reducing the power consumption of the device when SPI works

at high frequencies.

L9963T

Functional description

DS13590 - Rev 4

page 9/45

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