Lvd Reset Operation; Lvd Interrupt Operation; Low-Voltage Warning (Lvw) Interrupt Operation - NXP Semiconductors freescale KV4 Series Reference Manual

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Low-voltage detect (LVD) system

when the supply voltage falls below the selected trip point (VLVD).

LVDSC1[LVDF] is cleared by writing 1 to LVDSC1[LVDACK], but only if the

internal supply has returned above the trip point; otherwise, LVDSC1[LVDF]

remains set.

• The Low Voltage Warning Flag (LVWF) in the Low Voltage Status and Control 2

is set when the supply voltage falls below the selected monitor trip point (VLVW).

LVDSC2[LVWF] is cleared by writing one to LVDSC2[LVWACK], but only if the

internal supply has returned above the trip point; otherwise, LVDSC2[LVWF]

remains set.

18.3.1 LVD reset operation

By setting LVDSC1[LVDRE], the LVD generates a reset upon detection of a low-voltage

condition. The low-voltage detection threshold is determined by LVDSC1[LVDV]. After

an LVD reset occurs, the LVD system holds the MCU in reset until the supply voltage

rises above this threshold. The LVD field in the SRS register of the RCM module

(RCM_SRS[LVD]) is set following an LVD or power-on reset.

By configuring the LVD circuit for interrupt operation (LVDSC1[LVDIE] set and

LVDSC1[LVDRE] clear), LVDSC1[LVDF] is set and an LVD interrupt request occurs

upon detection of a low voltage condition. LVDSC1[LVDF] is cleared by writing 1 to

LVDSC1[LVDACK].

The LVD system contains a Low-Voltage Warning Flag (LVWF) in the Low Voltage

Detect Status and Control 2 Register to indicate that the supply voltage is approaching,

but is above, the LVD voltage. The LVW also has an interrupt, which is enabled by

setting LVDSC2[LVWIE]. If enabled, an LVW interrupt request occurs when

LVDSC2[LVWF] is set. LVDSC2[LVWF] is cleared by writing 1 to

LVDSC2[LVWACK].

LVDSC2[LVWV] selects one of the four trip voltages:

• Highest: V

KV4x Reference Manual, Rev. 2, 02/2015

Freescale Semiconductor, Inc.