®
Low Voltage Reset
-
LVR
The microcontroller contains a low voltage reset circuit in order to monitor the supply voltage of the
device. If the supply voltage of the device drops to within a range of 0.9V~V
LVR
such as might occur
when changing the battery, the LVR will automatically reset the device internally. The LVR includes
the following specifications: For a valid LVR signal, a low voltage, i.e. a voltage in the range be-
tween 0.9V~V
LVR
must exist for greater than 1ms. If the low voltage state does not exceed 1ms,
the LVR will ignore it and will not perform a reset function.
®
Watchdog Time-out Reset during Normal Operation
The Watchdog Time-out Reset during normal operation is the same as RES reset except that the
Watchdog Time-out flag TO will be set to 1.
®
Watchdog Time-out Reset during HALT
The Watchdog Time-out Reset during HALT is a little different from other kinds of reset. Most of the
conditions remain unchanged except that the Program Counter and the Stack Pointer will be
cleared to 0 and the TO flag will be set to 1. Refer to the A.C. Characteristics for t
SST
details.
The different types of resets described affect the reset flags in different ways. These flags known
as PDF and TO are located in the status register and are controlled by various microcontroller op-
erations such as the HALT function or Watchdog Timer. The reset flags are shown in the table:
TO
RESET Conditions
0
0
RES reset during power on
u
u
RES or LVR reset during normal operation
1
u
WDT time-out reset during normal operation
1
1
WDT time-out reset during HALT
²
u
²
stands for unchanged
Chapter 1 Hardware Structure
67
T im e r + 2
T im e r + 3
E x t e r n a l E v e n t
I n c r e m e n t
T im e r C o u n t e r
T im e r + 1
Low Voltage Reset Timing Chart
W D T T i m e - o u t
S S T T i m e - o u t
t
S S T
WDT Time-out Reset during HALT Timing Chart
W D T T i m e - o u t
S S T T i m e - o u t
I n t e r n a l R e s e t
t
R S T D
WDT Time-out Reset during Normal Operation Timing Chart
Содержание HT46R22
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Страница 10: ...P a r t I Microcontroller Profile Part I Microcontroller Profile 1...
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Страница 152: ...A p p e n d i x B Package Information Appendix B Package Information 143 B...
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