L9963E datasheet(59/184 Pages) STMICROELECTRONICS

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GPIO measurement formula

VGPIO=BINARY_CODE*VGPIO_ABS_RES, ifratio_abs_x_sel=0

VGPIO

VTREF=BINARY_CODE*VGPIO_RATIO_RES, if ratio_abs_x_sel=1

(6)

ADCs integrity is checked by Cell open with ADC_CROSS_CHECK = 1 and Voltage ADC BIST.

To cover latent failures, MCU can check if the divider is working properly by toggling the ratio_abs_x_sel bit:

MCU performs a GPIO conversion with ratio_abs_x_sel = 0 (absolute measurement)

MCU manually evaluates the quantity GPIOx_MEAS / VTREF_MEAS

MCU switches to ratio_abs_x_sel = 1 (ratiometric measurement)

MCU reads the ratiometric quantity in the GPIOx_MEAS registers and verifies that it matches the one

evaluated at point 2.

Note:

When toggling ratio_abs_x_sel bit, OT/UT and fast charge OT thresholds are not automatically updated, since

they are supposed to be written by the MCU. Hence, unwanted failures might be flagged. For this reason, it is

recommended to perform the divider integrity check at system startup.

4.9.2

GPIO1-9: standard digital I/O

The GPIO can be used in a standard digital input (Schmitt trigger) or digital Output buffer configuration,

depending on the configuration defined by dedicated register.

4.9.3

GPIO8-9: SPI commands

When the L9963E is connected to the micro (bottom device of the chain, SPIEN pin connected to the 5 V LDO

of the microcontroller), these two of the GPIO pins are used as SPI digital pins (the other 2 pins needed for SPI

communication are ISOLP/M pins):

•

ISOLM:CS (chip select) INPUT

•

ISOLP: SDI (serial data in) INPUT

•

GPIO8: SCLK (serial clock) INPUT

•

GPIO9: SDO (serial data out) BUFFERED OUTPUT

4.9.4

GPIO7: wake up feature

To enable GPIO7 as wakeup source, it must be configured as digital input (GPIO7_CONFIG = 10) and the

GPIO7_WUP_EN bit must be set to ‘1’:

•

Driving GPIO7 high for longer than TGPIO7_WAKEUP moves L9963E from a low power state to normal

mode.

•

A high logic value on GPIO7 pin keeps the device awake, also in case a GO2SLP command is received or

communication timeout expires.

•

In order to move the device to a low power state, the GPIO7 must be driven low and either a GO2SLP

command must be issued or the communication timeout has to expire.

4.9.5

GPIO1-2: FAULT feature

The fault information is transmitted in the chain by optocouplers connected to GPIO pins. The L9963E senses

the FAULT signal incoming from an upper device on GPIO1_FAULTH pin: external components must guarantee

that the voltage on the FAULTH pin lays inside the operating range. The L9963E transmits the fault signal to the

bottom of the chain through GPIO2_FAULTL pin that drives the optocoupler. External components must limit the

current coming out from GPIO2 pin when a logic ‘1’ is passed.

The FAULTL pin of the device at the bottom of the stack can be directly connected to the MCU digital input to

connect a fault interrupt.

For further information about FAULT line, refer to Section 4.3 FAULT line.

Refer to Section 6.7 FAULT line circuit for the application circuit.

L9963E

General purpose I/O: GPIOs

DS13636 - Rev 12

page 59/184

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