HT68F03 datasheet(121/139 Pages) HOLTEK

121 / 139 page

HT66F03/HT66F04/HT68F03/HT68F04

Rev. 1.00

121

April 16, 2010

Low Voltage Detector

- LVD

Each device has a Low Voltage Detector function, also

known as LVD. This enabled the device to monitor the

power supply voltage, VDD, and provide a warning signal

should it fall below a certain level. This function may be

especially useful in battery applications where the sup-

ply voltage will gradually reduce as the battery ages, as

it allows an early warning battery low signal to be gener-

ated. The Low Voltage Detector also has the capability

of generating an interrupt signal.

LVD Register

The Low Voltage Detector function is controlled using a

single register with the name LVDC. Three bits in this

fixed voltages below which a low voltage condition will

be detemined. A low voltage condition is indicated when

the LVDO bit is set. If the LVDO bit is low, this indicates

that the VDD voltage is above the preset low voltage

value. The LVDEN bit is used to control the overall

on/off function of the low voltage detector. Setting the bit

high will enable the low voltage detector. Clearing the bit

to zero will switch off the internal low voltage detector

circuits. As the low voltage detector will consume a cer-

tain amount of power, it may be desirable to switch off

the circuit when not in use, an important consideration in

power sensitive battery powered applications.

· 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

HT68F03 Datasheet(PDF) 121 Page - Holtek Semiconductor Inc

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