VNF1248F datasheet(51/79 Pages) STMICROELECTRONICS

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12.13

Control registers

Table 49. CR#1: control register 1 (read/write); address 01h

Bit

Default

Name

Description

AUTO_ON_DIS

Control bit to disable external FET automatic turn-on in case of bypass switch

saturation fault; in this case the DIAG pin will be driven low.

Specific for customer application test mode (‘Hot plug-in’).

Access to this field is allowed after the UNLOCK bit set to 1.

22:21

Unused

LOCKED_MODE_EN

Control bit needed to:

- Enable locked state entry in case of HWLO = 1 or EN = 0 events occurrence in

unlocked state

- Enable/Disable write access to control register fields in the locked state

CCM_CTRL_OFF

Trigger to stop CCM burst mode in unlocked/locked state

CCM_CTRL_ON

Trigger bit to start CCM burst mode in unlocked/locked state

NVM_DEF_CFG_UPLOAD

Trigger bit to upload NVM default configuration into correspondent RAM

configuration register fields (RAM overwrite)

NVM_DEF_CFG_EN

Control bit to allow reading/writing of correspondent NVM bit (through NVM

access procedure) for NVM default configuration enabling in fail-safe/locked

states

NVM bit = 1: fail-safe/locked parameters setting depending on values stored into

the NVM

NVM bit = 0: fail-safe/locked parameters setting depending on values stored into

RAM registers

Access to this bit is allowed after UNLOCK bit set to 1

15:14

0x0

FS_MODE

Fail-safe state behavior configuration (see Section 6.4: Fail-safe state)

Access to this field is allowed after the UNLOCK bit set to 1

DIN_CTRL_OPT

Unlocked state DIN control behavior configuration (see Section 6.2: Unlocked

state)

Access to this bit is allowed after UNLOCK bit set to 1

DIN_CTRL_EN

Unlocked state DIN control enable

Access to this bit is allowed after UNLOCK bit set to 1

GOSTBY

GOSTBY can be set to 1 only if UNLOCK = 1; in other words, trying to set this

bit to 1 when UNLOCK = 0 will have no effects and it maintains its previous

value.

GOSTBY can be reset to 0 also when UNLOCK = 0.

To set standby mode it is necessary to send two consecutive SPI frames, as

follows:

1st SPI write operation to set UNLOCK bit to 1

2nd SPI write operation to set GOSTBY bit to 1 and EN bit to 0

EN can be set to 1 only if UNLOCK = 1; in other words, trying to set this bit to 1

when UNLOCK = 0 will have no effects and it maintains its previous value.

EN can be reset to 0 also when UNLOCK = 0.

To set the EN bit and move the device from fail-safe/locked to unlocked state, it

is necessary to send two consecutive SPI frames as follows:

1st SPI write operation to set UNLOCK bit to 1

2nd SPI write operation to set GOSTBY bit to 0 and EN bit to 1

S_T_START

When it is set to 1, starts selected-test.

VNF1248F

SPI functional description

DS14109 - Rev 7

page 51/79

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