HT68F04 Holtek Semiconductor, HT68F04 Datasheet - Page 122

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

LVD Operation
The Low Voltage Detector function operates by compar-
ing the power supply voltage, V
voltage level stored in the LVDC register. This has a
range of between 2.0V and 4.4V. When the power sup-
ply voltage, V
the LVDO bit will be set high indicating a low power sup-
ply voltage condition. The Low Voltage Detector func-
tion is supplied by a reference voltage which will be
automatically enabled. When the device is powered
down the low voltage detector will remain active if the
LVDEN bit is high. After enabling the Low Voltage De-
tector, a time delay t
cuitry to stabilise before reading the LVDO bit. Note also
that as the V
the voltage nears that of V
LVDO transitions.
Rev. 1.00
DD
DD
voltage may rise and fall rather slowly, at
, falls below this pre-determined value,
LVD Operation
LVDS
should be allowed for the cir-
LVD
, there may be multiple bit
DD
, with a pre-specified
122
HT66F03/HT66F04/HT68F03/HT68F04
The Low Voltage Detector also has its own interrupt
which is contained within one of the Multi-function inter-
rupts, providing an alternative means of low voltage de-
tection, in addition to polling the LVDO bit. The interrupt
will only be generated after a delay of t
bit has been set high by a low voltage condition. When
the device is powered down the Low Voltage Detector
will remain active if the LVDEN bit is high. In this case,
the LVF interrupt request flag will be set, causing an in-
terrupt to be generated if V
voltage. This will cause the device to wake-up from the
SLEEP or IDLE Mode, however if the Low Voltage De-
tector wake up function is not required then the LVF flag
should be first set high before the device enters the
SLEEP or IDLE Mode.
DD
falls below the preset LVD
LVD
after the LVDO
April 16, 2010
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