Rev. 1.10
178
October 23, 2020
Rev. 1.10
179
October 23, 2020
BC66F5652
2.4GHz RF Transceiver A/D Flash MCU
BC66F5652
2.4GHz RF Transceiver A/D Flash MCU
Low Voltage Detector – LVD
The device has a Low Voltage Detector function, also known as LVD. This enables the device to
monitor the power supply voltage, V
DD
, 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 six 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
DD
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.
• LVDC Register
Bit
7
6
5
4
3
2
1
0
Name
—
—
LVDO
LVDEN
—
VLVD2
VLVD1
VLVD0
R/W
—
—
R
R/W
—
R/W
R/W
R/W
POR
—
—
0
0
—
0
0
0
Bit 7~6
U
nimplemented, read as “0”
Bit 5
LVDO
: LVD output flag
0: No Low Voltage detected
1: Low Voltage detected
Bit 4
LVDEN
: Low Voltage Detector Enable control
0: Disable
1: Enable
Bit 3
unimplemented, read as “0”
Bit 2~0
VLVD2~VLVD0
: LVD Voltage selection
000: Reserved
001: 2.0V
010: 2.4V
011: 2.7V
100: 3.0V
101: 3.3V
110: 3.6V
111: Reserved
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 has a range of between 2.0V and 3.6V.
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. 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.