L9969T datasheet(14/70 Pages) STMICROELECTRONICS

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Figure 7. VDD Monitoring and dependencies

VDD_max

VDD_THH

VDD

VDD_THL

VDD_POR

NABE

Outputs on

off

high

low

tPOR

tFIL_ON

tFIL_OFF

power on reset

switched OFF

2.6.2.2

VDD undervoltage

If the voltage between pins VDD and GNDABE is below the lower VDD-monitoring threshold (VDD_THL), the output

stages are switched off after a filtering time (tFIL_OFF) and an active low signal is generated at the bi-directional

pin NABE. After a transition from an undervoltage to a regular voltage between pins VDD and GNDABE, the signal

at pin NABE is (automatically) set high again once the filtering time (tFIL_ON) has expired. Writing new information

to configuration registers is possible.

If VDD falls below the power-on-reset supply voltage (VDD_RES) all stages are switched off and NABE is switched

active low. When VDD is rising above the power-on-reset supply voltage threshold (VDD_POR), the ASIC will

remain in POR until a time tPOR is run out, then all registers will be reset to their respective default state (all

registers cleared to default).

2.6.2.3

VDD overvoltage

If the voltage between pins VDD and GNDABE is above the upper VDD- monitoring threshold (VDD_THH), all output

stages are switched off after a filtering time (tFIL_OFF) and an active low signal is generated at the bi-directional

pin NABE.

After a transition from an overvoltage to a regular voltage between pins VDD and GNDABE, the behavior of the

NABE level and the output stages depend on the configuration of the bit CONFIG0 of STATCON_REG:

•

1: NABE is latched and the outputs remain off. A return to normal operation is only possible with power-on

reset or by changing the bit STATCON_REG.CONFIG0 via SPI → 0.

•

0: NABE is inactive after VDD returned to its regular operating voltage and the filtering time has expired.

The power stages are enabled again automatically. Writing new information to configure registers is

possible.

L9969x

Electrical specifications

DS14029 - Rev 6

page 14/70

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