Specifications

S1C62N82 TECHNICAL SOFTWARE EPSON II-49
CHAPTER 3: PERIPHERAL CIRCUITS (SVD Circuit and Heavy Load Protection Function)
Heavy load protec-
tion function
There are two ways to operate the heavy load protection
function:
• Operation through the HLMOD register
The heavy load protection function may be operated by
writing "1" on the HLMOD register (address 0FAH, D3, R/
W). Simultaneously, the SVD circuit will turn ON and
supply voltage detection by hardware every 2 Hz (0.5 sec)
will automatically be performed.
Operation through the HLMOD register is useful when
heavy load can be anticipated such as when S1C62N82
drives the piezo buzzer. The operation timing chart is
shown in Figure 3.9.2.
Supply voltage
Criteria voltage
HLMOD register
Heavy load
protection mode
2 Hz clock
SVD circuit
SVDDT
SVDON register
Fig. 3.9.2
Timing chart of supply
voltage detection opera-
tion through the HLMOD
register
• Operation through the SVDON register
The SVD circuit will turn ON by writing "1" on the
SVDON register (address 0FAH, D0, R/W) and supply
voltage detection will be performed. By writing "0" on the
SVDON register, the detection result is stored in the
SVDDT register. If this results in the supply voltage being
lower than the criteria voltage, the heavy load protection
function will operate. In other words, the SVD circuit in
this case serves as a sensor for detecting the operational
state of the heavy load protection function.