HT68F14 HOLTEK [Holtek Semiconductor Inc], HT68F14 Datasheet - Page 119

• Manufacturer Part Number: HT68F14
• Description: Enhanced I/O Flash Type MCU
• Manufacturer: HOLTEK [Holtek Semiconductor Inc]

Low Voltage Detector - LVD
Rev. 1.10
Name
R/W
POR
Bit 7~6
Bit 5
Bit
Bit 3
Bit 2~0
LVD Register
Bit
LVDC Register
If the system is woken up by an interrupt, then two possible situations may occur. The first is where the
related interrupt is disabled or the interrupt is enabled but the stack is full, in which case the program
will resume execution at the instruction following the HALT instruction. In this situation, the interrupt
which woke-up the device will not be immediately serviced, but will rather be serviced later when the
related interrupt is finally enabled or when a stack level becomes free. The other situation is where the
related interrupt is enabled and the stack is not full, in which case the regular interrupt response takes
place. If an interrupt request flag is set high before entering the SLEEP or IDLE Mode, the wake-up
function of the related interrupt will be disabled.
Each device has a Low Voltage Detector function, also known as LVD. This enabled the device to
monitor the power supply voltage, V
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.
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 condition will be determined. A low voltage condition is indicated when the LVDO bit is set. If
the LVDO bit is low, this indicates that the V
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.
unimplemented, read as 0
LVDO: LVD Output Flag
LVDEN: low voltage detector control
unimplemented, read as 0
VLVD2 ~ VLVD0: select LVD voltage
7
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
6
LVDO
R
5
0
DD
LVDEN
, and provide a warning signal should it fall below a certain
R/W
119
4
0
Enhanced I/O Flash Type MCU
DD
HT68F13/HT68F14/HT68F15
voltage is above the preset low voltage value. The
3
VLVD2
R/W
2
0
VLVD1
R/W
1
0
February 9, 2011
VLVD0
R/W
0
0