HT46R64 Holtek Semiconductor Inc., HT46R64 Datasheet - Page 27

• Manufacturer Part Number: HT46R64
• Description: Ht46r64/ht46c64 -- A/d With Lcd Type 8-bit Mcu
• Manufacturer: Holtek Semiconductor Inc.

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 RTCC.3 to
enable/disable (1/0) the LVD circuit and read the LVD detector status (0/1) from RTCC.5; otherwise, the LVD function is
disabled.
The RTCC 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. 1.80
Bit No.
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.
0~2
6~7
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 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.
RT0~RT2 8 to 1 multiplexer control inputs to select the real clock prescaler output
the device enters the reset mode.
QOSC
LVDC
LVDO
Label
LVD enable/disable (1/0)
32768Hz OSC quick start-up oscillating
0/1: quickly/slowly start
LVD detection output (1/0)
1: low voltage detected, read only
Unused bit, read as 0
LVR
) has to remain in their
RTCC (09H) Register
Low Voltage Reset
27
The relationship between V
Note: V
Function
operation at 4MHz system clock.
OPR
is the voltage range for proper chip
HT46R64/HT46C64
DD
and V
LVR
February 14, 2006
is shown below.