BC68F0031 Datasheet, PDF (118/148 Pages) Holtek Semiconductor Inc – I/O RF Transparent Transmission Flash MCU

BC68F0031
I/O RF Transparent Transmission Flash MCU
LVD Operation
The Low Voltage Detector function operates by comparing the power supply voltage, VDD, with a
pre-specified voltage level stored in the LVDC register. This has a range of between 1.8V and 4.0V.
When the power supply voltage, VDD, falls below this pre-determined value, the LVDO bit will
be set high indicating a low power supply voltage condition. The Low Voltage Detector function
is supplied by a reference voltage which will be automatically enabled. When the device is in
the SLEEP mode, the low voltage detector will be disabled even if the LVDEN bit is high. After
enabling the Low Voltage Detector, a time delay tLVDS should be allowed for the circuitry to stabilise
before reading the LVDO bit. Note also that as the VDD voltage may rise and fall rather slowly, at the
voltage nears that of VLVD, there may be multiple bit LVDO transitions.
VDD
VLVD
LVDEN
LVDO
tLVDS
Note: The tLVR and tLVD de-bounce clock come from LIRC, specified by tLVR and tLVD in the LVD/LVR
Electrical Characteristics.
LVD Operation
The Low Voltage Detector also has its own interrupt which is contained within one of the Multi-
function interrupts, providing an alternative means of low voltage detection, in addition to polling
the LVDO bit. The interrupt will only be generated after a delay of tLVD after the LVDO bit has been
set high by a low voltage condition. In this case, the LVF interrupt request flag will be set, causing
an interrupt to be generated if VDD falls below the preset LVD voltage. This will cause the device
to wake-up from the IDLE Mode, however if the Low Voltage Detector wake up function is not
required then the LVF flag should be first set high before the device enters the IDLE Mode.
Rev. 1.01
118
April 11, 2017