Cmsemicon CMS32L051 - Chapter 23 Voltage Detection Circuit; 23.1 Function of voltage detection circuit

V1.2.2
CMS32L051 User Manual |Chapter 23 Voltage Detection Circuit
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Chapter 23 Voltage Detection Circuit
23.1 Function of voltage detection circuit
The voltage detection circuit sets the operating mode and sense voltage (V
LVDH
, V
LVDL
, V
LVD
) via option
bytes (000C1H). Voltage Detection (LVD) circuitry has the following functions.
 voltage (V
DD
) with the sense voltage (V
LVDH
, V
LVDL
, V
LVD
). to generate an internal
reset or internal interrupt signal.
 (V
LVDH
, V
LVDL
) can select 12 detection levels via option bytes
(refer to Chapter 26 option bytes).


reset before the supply voltage reaches the operating voltage range shown in the AC characteristics of the data
sheet; When the supply voltage drops, it must be reset through deep sleep mode transfer, voltage detection
circuitry, or external reset before the supply voltage drops below the operating voltage range. The operating
voltage range depends on the setting of the user option bytes (000C2H/010C2H).
(a) Interrupt & reset mode (LVIMDS1, LVIMDS0=1, 0 for option bytes)
Select 2 sense voltages (V
LVDH
, V
LVDL
) and high voltage sense levels (V
LVDH
) via option byte 000C1H) is
used to release reset or interrupt, and low voltage sense level (V
LVDL
) is used to generate a reset.
(b) Reset mode (LVIMDS1, LVIMDS0=1, 1 for option bytes).
Use option byte 000C1H to select 1 sense voltage (V
LVD
) to generate or dereset.
(c) Interrupt mode (LVIMDS1, LVIMDS0=0, 1 for option bytes).
Use option byte 000C1H to select one sense voltage (V
LVD
) to generate an interrupt or to release reset. In
each mode, the following interrupt signals and internal reset signals are generated.
Interrupt & reset mode
(LVIMDS1, LVIMDS0=1, 0)
Reset mode
(LVIMDS1, LVIMDS0=1, 1)
Interrupt mode
(LVIMDS1, LVIMDS0=0, 1)
When the operating voltage drops,
when detectedVDD＜

internal reset is released;
After a reset occurs, the internal reset
state of the LVD is continued
VLVDH, an interrupt request signal is
generated; When detected
When detectedVDD＜VLVD, an
internal reset is generated.

detected
When VDD＜VLVDL, an internal reset
is generated;

of the LVD is released.

internal reset is released.
After the internal reset of the LVD is
released, if detected
VDD＜
Generates an interrupt request signal
(INTLVI).
When the voltage detection circuit is running, it is possible to confirm whether the supply voltage is
greater than or equal to the sense voltage or less than the sense voltage by reading the voltage
detection flag (LVIF: bit0 of the voltage detection register (LVIM)).
If a reset occurs, bit0 (LVIRF) of the reset control flag register (RESF) is set to 1. For more
information on RESF registers, refer to Chapter 21 Reset Functions.