mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 404

• Manufacturer Part Number: mcf51jf128
• Description: Mcf51jf128 Reference Manual
• Manufacturer: Freescale Semiconductor, Inc

Low-Voltage Detect (LVD) System
18.3.1 LVD Reset Operation
By setting the LVDRE bit, the LVD generates a reset upon detection of a low voltage
condition. The low voltage detection threshold is determined by the LVDV bits. After an
LVD reset occurs, the LVD system holds the MCU in reset until the supply voltage rises
above this threshold. The LVD bit in the SRS register is set following an LVD or power-
on reset.
18.3.2 LVD Interrupt Operation
By configuring the LVD circuit for interrupt operation (LVDIE set and LVDRE clear),
LVDSC1[LVDF] is set and an LVD interrupt request occurs upon detection of a low
voltage condition. The LVDF bit is cleared by writing one to the LVDSC1[LVDACK]
bit.
18.3.3 Low-Voltage Warning (LVW) Interrupt Operation
The LVD system contains a low voltage warning flag (LVWF) 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 the LVDSC2[LVWIE] bit. If enabled, an LVW interrupt
request occurs when the LVWF is set. LVWF is cleared by writing one to the
LVDSC2[LVWACK] bit.
The LVDSC2[LVWV] bits select one of four trip voltages:
404
• Highest (V
• Two mid-levels (V
• Lowest (V
(VLVW). The LVWF bit is cleared by writing one to the LVWACK bit, but only if
the internal supply has returned above the trip point; otherwise, the LVWF bit
remains set.
LVW1
LVW4
)
)
LVW3
MCF51JF128 Reference Manual, Rev. 2, 03/2011
and V
LVW2
Preliminary
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Freescale Semiconductor, Inc.