em78f644nso28s ELAN Microelectronics Corp, em78f644nso28s Datasheet - Page 159

• Manufacturer Part Number: em78f644nso28s
• Description: Flash Series 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

Product Specification (V1.0) 05.05.2010
(This specification is subject to change without further notice)
Internal Reset
Figure 6-26 LVD Waveform Characteristics Showing Detection Point in an External Voltage Condition
LVDXIF
Vdd
Figure 6-26 below shows the LVD module detection point in an external voltage
condition.
When Vdd drops but above V
When Vdd drops below V
When Vdd drops below V
When Vdd drops below V
register status and halts its operation, but oscillation remains active.
LVDIF is also set to “1” and the next instruction will branch to interrupt vector. The
LVD interrupt flag is cleared to “0” by software.
The internal LVD module uses the internal circuit to match low voltage
During the Sleep mode, the LVD module continues to operate. If the
When system resets, the LVD flag is cleared.
detection. When the LVDEN is set to enable the LVD module, the
current consumption will increase about 10uA.
device voltage drops slowly and crosses the detection point, the LVDIF
bit will be set and the device will not wake-up from Sleep mode. Until
the other wake-up sources wake-up EM78F648/548N, the LVD
interrupt flag setting will remain at priority status.
Vdd < Vreset not longer than 80us,system keep on going
<50,40,30 us
LVD
RESET
RESET
, LVDIF is set to “1”. If the global ENI is enabled,
LVD
EM78F648/644/642/641/548/544/542/541N
at less than 80us, the system will keep all the
at more than 80us, system RESET will occur.
, LVDIF is kept at “0”.
NOTE
LVDXIF clear by software
>50,40,30 us
8-Bit Microcontroller
System occur reset
18ms
V
V
RESET
LVD
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