HT46RU67 Holtek Semiconductor Inc., HT46RU67 Datasheet - Page 34

• Manufacturer Part Number: HT46RU67
• Description: Ht46ru67/ht46cu67 -- A/d Type 8-bit Mcu With Lcd
• 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 this microcontroller. These
two functions can be enabled/disabled by options. Once the LVD option is enabled, the user can use the RTCC.3 bit 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.
Note:
The LVR has the same effect or function with the exter-
nal RES signal which performs a chip reset. During
HALT state, both LVR and LVD are disabled.
The LVR state requires the following specifications:
Note:
Rev. 1.00
The low voltage (0.9V~V
more than 1ms, otherwise, the circuits remain in their
original state. 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 a chip reset.
Bit No.
0~2
6, 7
3
4
5
controlled by LVR ROM code option. The relationship between LVR and LVD options and LVDC are as shown.
*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,
* Once the LVD function is enabled the reference generator should be enabled; otherwise the reference generator is
clock pulses before entering the normal operation.
the device enters the reset mode.
RT0~RT2
LVDC*
QOSC
LVDO
Label
LVR
) has to be maintained for
8 to 1 multiplexer control inputs to select the real clock prescaler output
LVD enable/disable (1/0)
32768Hz OSC quick start-up oscillating
0/1: quick/slow start
LVD detection output (1/0)
1: low voltage detected, read only
Unused bit, read as 0
RTCC (09H) Register
Low Voltage Reset
34
The relationship between V
Note: V
operation at 4MHz system clock.
OPR
Function
is the voltage range for proper chip
HT46RU67/HT46CU67
DD
and V
LVR
February 27, 2008
is shown below.