L9965TS datasheet(47/62 Pages) STMICROELECTRONICS

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Symbol

PARAMETER

TEST CONDITIONS

MIN

TYP MAX UNIT

RBNE_PD

BNE weak pulldown resistor to GND

0.4

1.6

MΩ

BNE

RFLT_PD

FLT weak pulldown resistor to GND

0.4

1.6

MΩ

FLT

IWKP

WKP output current

WKP

VWKP_DROP

Voltage drop from

VB to WKP

IWKP = -0.5mA

0.5

WKP

VWKP_DET Threshold to set WKP_STATUS to '1' WKP_SET =1

1.5

WKP

5.10

Configuration lock (UNLOCK_KEY)

To prevent inadvertent modification of Safety Relevant Registers (SRR) and Safety Latent Registers (SLR)

(indicated in the register map) such register map sectors are protected by a lock field.

By default, SRR/SLR registers are locked. To configure the device, the following procedure shall be implemented:

Procedure 3: Configuration Lock/Unlock

1. Write 0x55 in the SPECIAL_REG.SPECIAL_KEY register to enter in partial unlock

2. Write 0x33 in the SPECIAL_REG.SPECIAL_KEY register to confirm the unlock

3. Any configuration register must be written within TCFG_TIMEOUT

a. If the TCFG_TIMEOUT expires, the lock is automatically re-applied

4. Write 0xAA in the SPECIAL_REG.SPECIAL_KEY to re-apply the lock.

Trying to write a protected register (SRR or SLR) without unlocking it before results in command being ignored.

Writing lock protected registers only changes the current configuration loaded in the SPI registers. To save the

configuration and guarantee a correct reload at each powerup, the update has to be pushed into the Non-Volatile

Memory (NVM) as described in Section 5.12.

Note:

For temporary modifications to the IC configuration, which do not need to be pushed in the Non-Volatile Memory

(NVM), it is recommended to disable the Configuration Register Data Integrity Check (CONF_CRC).

Note:

5.10.1

Electrical parameters

Table 48. Configuration lock electrical parameters

Symbol

Parameter

Test condition

Min

Typ

Max

Unit

TCFG_TIMEOUT

Configuration lock timeout

Tested in SCAN

5.11

Software reset (SW_RST)

It is possible to reset the device configuration sending a SW_RST sequence.

Once triggered, the software reset procedure resets all SPI registers to their default values, including the lock

protected ones.

The software reset procedure also acts on SPI registers clear on read flags depending on their diagnosis source:

•

Runtime diagnosis: VB_UV, V3V3_INT_OV, V5V_OV, V5V_UV, V5V_OT, WKP_OT, GND_LOSS,

TRIM_CYC_CRC_FAIL, CONF_CYC_CRC_FAIL, OSC_FAIL, FLT_ERR, WKP_ERR, BNE_ERR,

V5V_OC, TSD). These status bits are cleared by sw reset only if faults are no more detected.

•

One time diagnosis without results retention (analog comparators BIST and oscillator monitor BIST):

POR_SLEEP_ASSERTED, WAKEUP_CYCLIC_END, WAKEUP_CYCLIC_TRX_TIMEOUT,

BIST_ANA_DONE, BIST_ANA_FAIL, BIST_OSC_DONE, BIST_OSC_FAIL. In this case the status bits are

always cleared by sw reset.

•

One time diagnosis with results retention: TRIM_NVM_CRC_FAIL, CONF_NVM_CRC_FAIL,

NVM_VERIFY_ERR. These status bits are cleared by sw reset only if diagnosis ends with no fault

detected.

L9965T/L9965TS

Functional description

DS14987 - Rev 1

page 47/62

L9965TS Datasheet(PDF) 47 Page - STMicroelectronics

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