HT68F04 Holtek Semiconductor, HT68F04 Datasheet - Page 121

• Manufacturer Part Number: HT68F04
• Description: Small Package Enhanced Flash Type 8-Bit MCU
• Manufacturer: Holtek Semiconductor

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, V
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
register, VLVD2~VLVD0, are used to select one of eight
·
Rev. 1.00
LVDC Register
Bit 7~6
Bit 5
Bit
Bit 3
Bit 2~0
Name
R/W
POR
Bit
unimplemented, read as ²0²
LVDO: LVD Output Flag
LVDEN: Low Voltage Detector Control
unimplemented, read as ²0²
VLVD2 ~ VLVD0: Select LVD Voltage
0: No Low Voltage Detect
1: Low Voltage Detect
0: Disable
1: Enable
000: 2.0V
001: 2.2V
010: 2.4V
011: 2.7V
100: 3.0V
101: 3.3V
110: 3.6V
111: 4.4V
¾
¾
¾
7
DD
, and provide a warning signal
¾
¾
¾
6
LVDO
R
5
0
LVDEN
121
HT66F03/HT66F04/HT68F03/HT68F04
R/W
4
0
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 V
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.
¾
¾
¾
3
DD
voltage is above the preset low voltage
VLVD2
R/W
2
0
VLVD1
R/W
1
0
April 16, 2010
www.DataSheet4U.com
VLVD0
R/W
0
0