VX6953CB datasheet(25/107 Pages) STMICROELECTRONICS

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8209023 Rev 5

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VX6953CB

Functional description

3.4.3

Internal power-on reset (POR)

The VX6953CB internally performs a power-on reset (POR) when the 1V2 Vcore digital

supply rises through the trigger level, Vtrig_rising. Similarly, if the 1V2 Vcore digital power

supply falls through the trigger level, Vtrig_falling, then the power-on reset will also trigger.

Definitions

Rise threshold voltage (VTRIGR) is the supply voltage level that is recognised by the POR

as voltage “HIGH”. Only after the supply reaches this level does the output of POR change

to high level if it is off, after a specified amount of delay.

Fall threshold voltage (VTRIGF) is the supply voltage level that is recognised by the POR

as voltage “LOW”. Only after the supply reaches this level does the output of POR change

to low (ground) level if it is on.

Burst width (pw). Burst is the negative pulse riding the supply signal. The burst width is

measured as the amount of duration for which the supply signal dropped beyond the

threshold levels.

Delay duration (TPOR) is defined as the time duration for which POR stays off before

repowering. Each reset of POR will impart a specified delay duration before POR repowers.

Figure 9. POR timing

Table 7. POR cell characteristics

Symbol

Constraint

Min

Typ.

Max

Units

VTRIGR

POR rise voltage detection

0.95

VTRIGF

POR fall voltage detection

0.4

Tburst (pw)

Burst filter

µs

Tpor

Delay duration

µs

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