VNF9D5F datasheet(6/106 Pages) STMICROELECTRONICS

6 / 106 page

2.2

State diagrams and operating modes

The device and the channel state diagrams are reported in Figure 3 and Figure 4 respectively; whilst the Table 2

shows the description of the operating modes.

Figure 3. Device state diagram

(1) SPI communication only if VDD is present.

Start

Sleep mode

from V

and V

– Outputs: inactive

– SPI: inactive

– Registers: cleared

– Diagnostics: not available

– V

REG

< V

POR

– Low supply current

Pre-standby mode

– Outputs: inactive

– SPI: active

– Registers: read/writeable

– Diagnostics: SPI possible

– Timer 100 μs running

– I²t countersdecreasing

Normal mode

– Outputs: according to SPI

– SPI: active (1)

– Registers: read/writeable

ADC conversion possible

– Diagnostics: SPI and

– Regular toggling of WDTB

necessary within timeout

period tWDTB

Standby mode

– Outputs: inactive

– SPI: inactive

– Registers: frozen

– Diagnostics: not available

from V

and V

– Low supply current

Fail-safe mode

– Outputs: according to DIx,

DIOTPx, OTP_MCUext

– Registers: read/write possible,

cleared if entered after SW reset

– SPI: active (1)

ADC conversion possible only

– Diagnostics: available through SPI (1),

in asynchronous mode

otherwise 0

– Reset bit = 1 if SW reset or POR,

SPI sequences:

1. UNLOCK* = 1 AND EN = 1

2. EN* = 0 AND GOSTBY* = 1

within tWDTB

WDTB toggling

VREG < VREG_POR_L

STDBY_NOT high OR

(CSN low AND V

DD_TH

VREG > VREG_POR_H

(CSN low AND VDD > VDD_TH)]

[STDBY_NOT = 1 OR

STDBY_NOT low AND

(CSN high OR V

DD_TH

) AND

Timer 100 μs elapsed

all I²t counters = 0 AND

System startup,

VCC present

(CSN low AND V

DD_TH

)

STDBY_NOT high OR

(CSN high OR V

DD_TH

)

STDBY_NOT low AND

for at least 14 ms

SW reset OR EN* = 0 OR

tWDTB timeout

SPI sequences:

1. UNLOCK* = 1

2. EN* = 1 AND GOSTBY* = 0

VREG < VREG_POR_L

AND V

REG

> V

REG_POR_H

As showed in the above figure, the device features five different operating modes:

•

Standby mode

•

Fail-safe mode

•

Pre-standby mode

•

Normal mode

•

Sleep mode

The entering/leaving conditions as well as the operating modes characteristics are described in the Table 2.

VNF9D5F

Functional description

DS13946 - Rev 6

page 6/106

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