HT45F43 datasheet(128/152 Pages) HOLTEK

128 / 152 page

LVDC Register

Bit

76543210

Name

¾¾

LVDO

LVDEN

VLVD2

VLVD1

VLVD0

R/W

¾¾

R/W

POR

¾¾

000

Bit 7~6

unimplemented, read as

²0²

Bit 5

LVDO: LVD Output Flag

0: No Low Voltage Detect

1: Low Voltage Detect

Bit

LVDEN: Low Voltage Detector Control

0: Disable

1: Enable

Bit 3

unimplemented, read as

²0²

Bit 2~0

VLVD2 ~ VLVD0: Select LVD Voltage

000: 2.0V

001: 2.2V

010: 2.4V

011: 2.7V

100: 3.0V

101: 3.3V

110: 3.6V

111: 4.4V

LVD Operation

The Low Voltage Detector function operates by comparing the power supply voltage, VDD, with a

pre-specified voltage level stored in the LVDC register. This has a range of between 2.0V and 4.4V.

When the power supply voltage, VDD, falls below this pre-determined value, the LVDO bit will be set

high indicating a low power supply voltage condition. The Low Voltage Detector function is supplied

by a reference voltage which will be automatically enabled. When the device is powered down the low

voltage detector will remain active if the LVDEN bit is high. After enabling the Low Voltage Detector,

a time delay tLVDS should be allowed for the circuitry to stabilise before reading the LVDO bit. Note also

that as the VDD voltage may rise and fall rather slowly, at the voltage nears that of VLVD, there may be

multiple bit LVDO transitions.

The Low Voltage Detector also has its own interrupt which is contained within one of the

Multi-function interrupts, providing an alternative means of low voltage detection, in addition to

polling the LVDO bit. The interrupt will only be generated after a delay of tLVD after the LVDO bit has

been set high by a low voltage condition. When the device is powered down the Low Voltage Detector

will remain active if the LVDEN bit is high. In this case, the LVDF interrupt request flag will be set,

causing an interrupt to be generated if VDD falls below the preset LVD voltage. This will cause the

device to wake-up from the SLEEP or IDLE Mode, however if the Low Voltage Detector wake up

function is not required then the LVDF flag should be first set high before the device enters the SLEEP

or IDLE Mode.

Rev. 1.20

128

September 15, 2011

HT45F23/HT45F43

8-Bit Flash MCU with Op Amps & Comparators

V D D

V L V D

L V D E N

L V D O

t L V D S

LVD Operation

HT45F43 Datasheet(PDF) 128 Page - Holtek Semiconductor Inc

HT45F43 Datasheet(HTML) 128 Page - Holtek Semiconductor Inc

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