Freescale Semiconductor MCF51QE128RM LVD and LVW Trip Point Typical Values1, Lvwf Lvdv Lvwv Lvwie

Models: MCF51QE128RM

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Chapter 5 Resets, Interrupts, and General System Control

7

6

5

4

3

2

1

0

R

W

POR:

LVR:

Any other reset:

LVWF

0

LVDV

LVWV

LVWIE

0

0

0

 

 

 

 

 

 

LVWACK

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

01

0

0

0

0

0

0

0

01

0

U

U

0

0

0

0

01

0

U

U

0

0

0

0

1LVWF is set when VSupply transitions below the trip point or after reset and VSupply is already below VLVW.

Figure 5-9. System Power Management Status and Control 3 Register (SPMSC3)

 

 

Table 5-10. SPMSC3 Register Field Descriptions

 

 

 

Field

 

Description

 

 

7

Low-Voltage Warning Flag. The LVWF bit indicates the low voltage warning status.

LVWF

0

Low voltage warning not present.

 

1

Low voltage warning is present or was present.

 

 

6

Low-Voltage Warning Acknowledge. Writing a 1 to LVWACK clears LVWF if a low voltage warning is not present.

LVWACK

 

 

 

 

5

Low-Voltage Detect Voltage Select. The LVDV bit selects the LVD trip point voltage (VLVD).

LVDV

0

Low trip point selected (VLVD = VLVDL).

 

1

High trip point selected (VLVD = VLVDH).

4

Low-Voltage Warning Voltage Select. The LVWV bit selects the LVW trip point voltage (VLVW).

LVWV

0

Low trip point selected (VLVW = VLVWL).

 

1

High trip point selected (VLVW = VLVWH).

3

Low-Voltage Warning Interrupt Enable. This bit enables hardware interrupt requests for LVWF.

LVWIE

0

Hardware interrupt disabled (use polling).

 

1

Request a hardware interrupt when LVWF is set.

 

 

2–0

Reserved, should be cleared.

 

 

 

Table 5-11. LVD and LVW Trip Point Typical Values1

LVDV:LVWV

LVW Trip Point

LVD Trip Point

 

 

 

00

VLVWL = 2.15

VLVDL = 1.86

 

 

 

01

VLVWL = 2.48

 

 

 

 

10

VLVWL = 2.15

VLVDL = 2.15

Not Recommended

 

 

 

 

 

11

VLVWL = 2.48

 

 

 

 

1See the MCF51QE128 Data Sheet for minimum and maximum values.

MCF51QE128 MCU Series Reference Manual, Rev. 3

106

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Freescale Semiconductor MCF51QE128RM manual LVD and LVW Trip Point Typical Values1, Lvwf Lvdv Lvwv Lvwie, Lvdvlvwv