HT48R0AA-1
Low Voltage Reset - LVR
The relationship between VDD and VLVR is shown below.
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~VLVR, such as when changing a battery, the LVR
will automatically reset the device internally.
V
D
D
V
O P R
5
.
5
V
5
.
5
V
V
L
V
R
The LVR includes the following specifications:
3
.
0
V
·
The low voltage (0.9V~VLVR) has to remain in its origi-
nal state for longer than 1ms. If the low voltage state
does not exceed 1ms, the LVR will ignore it and will
not perform a reset function.
2
.
2
V
0
.
9
V
·
The LVR uses an ²OR² function with the external RES
signal to perform a chip reset.
Note:
V
OPR is the voltage range for proper chip opera-
tion at 4MHz system clock.
V
D
D
5
.
5
V
L
V
R
D
e
t
e
c
t
V
o
l
t
a
g
e
V
L
V
R
0
.
9
0
V
V
R
e
s
e
t
S
i
g
n
a
l
R
e
s
e
t
N
o
r
m
a
l
O
p
e
r
a
t
i
o
n
R
e
s
e
t
*
1
*
2
Low Voltage Reset
Note: *1: To make sure that the system oscillator has stabilized, the SST provides an extra delay of 1024 system
clock pulses before starting the normal operation.
*2: Since low voltage state has to be maintained its original state for longer than 1ms, therefore after 1ms delay,
the device enters the reset mode.
Configuration Options
The following table shows all kinds of configuration options in the microcontroller. All of the configuration options must
be defined to ensure proper system functioning.
Items
Configuration Options
WDT clock source: WDT oscillator or fSYS/4
1
2
3
4
5
6
7
8
WDT function: enable or disable
CLRWDT instructions: 1 or 2 instructions
PA bit wake-up enable or disable
PA, PB, PC, PD pull-high enable or disable (By port)
BZ/BZ enable or disable
LVR enable or disable
System oscillator: RC or crystal
Rev. 1.10
17
July 27, 2007
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
