L9963E datasheet(15/184 Pages) STMICROELECTRONICS

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During Sleep state, the current consumption is significantly reduced to ISLEEP current value: only the

Communication wake up sources monitoring, low-speed oscillator for cyclic wake up timer, and the corresponding

reference and power supply are activated.

Different events can cause a wake up, depending on the configuration decided by the microcontroller:

•

ISO COMM/SPI SIGNAL: this wake-up during a regular SLEEP mode state moves the L9963E FSM to Init

or Normal State. A proper signal will be detected as pre-wake up (simple edge readout), and later it must be

followed by a wake-up signal that will be decoded by the L9963E which, in the meanwhile, has entered in a

higher consumption mode (regulators turned ON, isolated RX/TX enabled). Any protocol frame recognized

as electrically consistent will wake up the device. However, the command will not be interpreted and thus no

execution takes place;

•

INTERNAL COUNTER: it is possible that the microcontroller defines an automatic wake up of L9963E

(when put in SLEEP mode) every TCYCLE_SLEEP, in order to perform the diagnostics in the CYCLIC

WAKEUP state;

•

GPIO SIGNAL: in case GPIO7 is configured as wake up source (GPIO7_WUP_EN = 1), a high logic level

on it will wake up L9963E;

•

FAULT: in case a fault is detected in an upper L9963E, a proper signal is communicated through the FAULT

line. The receiver connected to GPIO1/FAULTH pin will detect the event and the device will be forced to

evolve into the normal state, in order to transmit the fault downward.

The wake-up event coming from external wake up sources is verified by the Stby logic (pattern confirmation step)

before waking up the main logic (the main logic is kept under reset and its clock is gated off until the Sleep state is

left).

The wakeup sequence lasts TWAKEUP.

4.1.1.2

Operations in Sleep state

Only the Stand-by logic is working in Sleep state.

Table 7. Operations in Sleep state

Operation

Timing mode

Functions involved

Wake up Management

Always ON

Timers, Pin Input Buffer and ISO lines receiver ON. External sources activity

detection, receivers and input buffers powered

Awakening Pattern Detection

Once

Comparison logic

4.1.2

Init state

In Init state, after having been woken up, the device waits for the uP to send the Address assignment command.

Refer to Section 4.1.2.2 Addressing procedure.

If the address command is received before the Init timer expires (t_SHUT), the device address is stored into a

stand-by logic register (chip_ID) and the device goes to Normal state.

The chip_ID field is then locked and no longer editable. Two actions can correctly re-initialize the device

(including the chip_ID):

•

Hard reset: (POR_STBY)

•

Soft reset: it is recommended to set SW_RST and GO2SLP in the same frame

–

Note that Soft reset will leave communication timeout (CommTimeout) unmodified

–

Note that Soft reset will also clear the chip_ID

–

If only SW_RST is sent, the device will wait for CommTimeout and then move to Sleep state

If the Init timer (t_SHUT) expires before the command is received, the device goes back to Sleep state.

All references are powered, interfaces are ready data transmission. The commands sent by the micro-controller

can be read from both ISO lines and SPI pins. However, while in Init state, only the chip_ID, isotx_en_h and

iso_freq_sel fields are writable. It is not possible to write/read other registers.

Any failure is masked until the device receives an address.

L9963E

Device functional state

DS13636 - Rev 12

page 15/184

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