Rev. 1.00
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Rev. 1.00
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HT66FM5440
Brushless DC Motor A/D Flash MCU
HT66FM5440
Brushless DC Motor A/D Flash MCU
Bit 3
VBGEN
: Bandgap Voltage Output Enable control
0: Disable
1: Enable
Note that the Bandgap circuit is enabled when the LVD or LVR function is enabled or
when the VBGEN bit is set to 1.
Bit 2~0
VLVD2~VLVD0
: LVD Voltage selection
000: 4.0V
001: 4.0V
010: 4.0V
011: 4.0V
100: 4.0V
101: 4.0V
110: 4.0V
111: 4.0V
LVD Operation
The Low Voltage Detector function operates by comparing the power supply voltage, V
DD
, with
a pre-specified voltage level stored in the LVDC register. This pre-sepcified voltage level has a
fixed value of 4.0V. When the power supply voltage, V
DD
, 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 t
LVDS
should be allowed for the circuitry
to stabilise before reading the LVDO bit. Note also that as the V
DD
voltage may rise and fall rather
slowly, at the voltage nears that of V
LVD
, there may be multiple bit LVDO transitions.
V
DD
LVDEN
LVDO
V
LVD
t
LVDS
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 t
LVD
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 V
DD
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.