Renesas RL78 Series User Manual page 737

RL78/G1D
22.1 Functions of Voltage Detector
The operation mode and detection voltages (V
(000C1H).
The voltage detector (LVD) has the following functions.
● The LVD circuit compares the supply voltage (V
internal reset or internal interrupt signal.
● The detection level for the power supply detection voltage (V
byte as one of 12 levels (For details, see CHAPTER 25 OPTION BYTE).
● Operable in STOP mode.
● After power is supplied, the reset state must be retained until the operating voltage becomes in the range defined in
30.6 AC Characteristics. This is done by utilizing the voltage detection circuit or controlling the externally input
reset signal. After the power supply is turned off, this LSI should be placed in the STOP mode, or placed in the reset
state by utilizing the voltage detection circuit or controlling the externally input reset signal before the voltage falls
below the operating range. The range of operating voltage varies with the setting of the user option byte (000C2H or
010C2H).
(a) Interrupt & reset mode (option byte LVIMDS1, LVIMDS0 = 1, 0)
The two detection voltages (V
(V ) is used for releasing resets and generating interrupts. The low-voltage detection level (V
LVDH
generating resets.
(b) Reset mode (option byte LVIMDS1, LVIMDS0 = 1, 1)
The detection voltage (V
(c) Interrupt mode (option byte LVIMDS1, LVIMDS0 = 0, 1)
The detection voltage (V
The reset and internal interrupt signals are generated in each mode as follows.
Interrupt & reset mode
(LVIMDS1, LVIMDS0 = 1, 0)
Generates an interrupt request signal by
detecting V < V when the operating
DD LVDH
voltage falls, and an internal reset by
detecting V < V .
DD LVDL
Releases an internal reset by detecting
V ≥ V .
DD LVDH
While the voltage detector is operating, whether the supply voltage is more than or less than the detection level can be
checked by reading the voltage detection flag (LVIF: bit 0 of the voltage detection register (LVIM)).
Bit 0 (LVIRF) of the reset control flag register (RESF) is set to 1 if reset occurs. For details of the RESF register, see
CHAPTER 20 RESET FUNCTION.
R01UH0515EJ0120 Rev.1.20
Dec 16, 2016
CHAPTER 22 VOLTAGE DETECTOR
, V
LVDH LVDL
) with the detection voltage (V
DD
, V ) are selected by the option byte 000C1H. The high-voltage detection level
LVDH LVDL
) selected by the option byte 000C1H is used for generating/releasing resets.
LVD
) selected by the option byte 000C1H is used for releasing resets/generating interrupts.
LVD
Reset mode
(LVIMDS1, LVIMDS0 = 1, 1)
Releases an internal reset by detecting
V ≥ V .
DD LVD
Generates an internal reset signal by
detecting V < V
DD LVD
CHAPTER 22 VOLTAGE DETECTOR
, V ) for the voltage detector is set by using the option byte
LVD
, V , V
LVDH LVDL LVD
Retains the state of an internal reset by
the LVD immediately after a reset until
V ≥ V
DD
reset by detecting V
.
Generates an interrupt request signal
(INTLVI) by detecting V
V
LVD
released.
, V , V ), and generates an
LVDH LVDL LVD
) can be selected by using the option
LVDL
Interrupt mode
(LVIMDS1, LVIMDS0 = 0, 1)
. Releases the LVD internal
LVD
≥ V .
DD LVD
< V or V
DD LVD
after the LVD internal reset is
) is used for
≥
DD
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