HT45F65 Datasheet, PDF (203/231 Pages) Holtek Semiconductor Inc – Glucose Meter 8-Bit Flash MCU

HT45F65/HT45F66/HT45F67
Glucose Meter 8-Bit Flash MCU
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 supply voltage will
gradually reduce as the battery ages, as it allows an early warning battery low signal to be generated.
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 fixed voltages below which a
low voltage conditionwill be determined. A low voltage condition is indicatedwhen 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 certain 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
7
Name
—
R/W
—
POR
—
6
5
4
3
2
1
0
—
LVDO LVDEN
—
VLVD2 VLVD1 VLVD0
—
R
R/W
—
R/W
R/W
R/W
—
0
0
—
0
0
0
Bit 7~6
Bit 5
Bit 4
Bit 3
Bit 2~0
Unimplemented, read as "0"
LVDO: LVD Output Flag
0: No Low Voltage Detect
1: Low Voltage Detect
LVDEN: Low Voltage Detector Control
0: Disable
1: Enable
Unimplemented, read as "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: 4.0V
Rev. 1.60
203
November 24, 2015