HT45F43 datasheet(127/152 Pages) HOLTEK

127 / 152 page

Each pin on Port A can be setup using the PAWU register to permit a negative transition on the pin to

wake-up the system. When a Port A pin wake-up occurs, the program will resume execution at the

instruction following the

²HALT² instruction.

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

²HALT² 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.

Low Voltage Detector

- LVD

This 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 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 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.

HT45F23/HT45F43

8-Bit Flash MCU with Op Amps & Comparators

Rev. 1.20

127

September 15, 2011

HT45F43 Datasheet(PDF) 127 Page - Holtek Semiconductor Inc