HT46R71D Holtek Semiconductor, HT46R71D Datasheet - Page 25

• Manufacturer Part Number: HT46R71D
• Description: A/D with LCD Type 8-Bit MCU
• Manufacturer: Holtek Semiconductor

Low Voltage Reset/Detector Functions
There is a low voltage detector (LVD) and a low voltage reset circuit (LVR) implemented in the microcontroller. These
two functions can be enabled/disabled by options. Once the LVD options is enabled, the user can use the MODE.3 to
enable/disable (1/0) the LVD circuit and read the LVD detector status (0/1) from MODE.5; otherwise, the LVD function is
disabled.
The MODE register definitions are listed below.
The LVR has the same effect or function with the exter-
nal RES signal which performs chip reset. During HALT
state, LVR is disabled both LVR and LVD are disabled.
The microcontroller provides low voltage reset circuit in
order to monitor the supply voltage of the device. If the
supply voltage of the device is within the range
0.9V~V
tomatically reset the device internally.
The LVR includes the following specifications:
Note:
Rev. 1.00
The low voltage (0.9V~V
original state to exceed 1ms. If the low voltage state
does not exceed 1ms, the LVR will ignore it and do not
perform a reset function.
The LVR uses the OR function with the external RES
signal to perform chip reset.
Bit No.
0~1
6~7
2
3
4
5
LVR
*1: To make sure that the system oscillator has stabilized, the SST provides an extra delay of 1024 system
*2: Since a low voltage state has to be maintained in its original state for over 1ms, therefore after 1ms delay,
, such as changing a battery, the LVR will au-
clock pulses before entering the normal operation.
the device enters the reset mode.
LVDO
Label
LVDC
IRCC
Unused bit, read as 0
In HALT mode, IRC clock enable or disable selection bit.
0: IRC clock enable and Int.RCOSC on. 1: IRC clock disabled.
LVD enable/disable (1/0)
Unused bit, read as 0
LVD detection output (1/0)
1: low voltage detected, read only. 0: low voltage not detected.
Unused bit, read as 0
LVR
) has to remain in their
MODE (09H) Register
Low Voltage Reset
25
The relationship between V
Note: V
Function
operation at 4MHz system clock.
OPR
is the voltage range for proper chip
DD
and V
LVR
HT46R71D
January 9, 2006
is shown below.