upd78f0148m1gka1-9eu Renesas Electronics Corporation., upd78f0148m1gka1-9eu Datasheet - Page 659

• Manufacturer Part Number: upd78f0148m1gka1-9eu
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

Power-on-
clear circuit
(POC)
Low-voltage
detector
(LVI)
Regulator
µ
PD78F0148
Function
Power-on-
clear circuit
functions
Cautions for
power-on-
clear circuit
LVIM: Low-
voltage
detection
register
LVIS: Low-
voltage
detection level
selection
register
When used as
reset
When used as
interrupt
Cautions for
low-voltage
detector
IMS: Internal
memory size
switching
register
IXS: Internal
expansion
RAM size
switching
register
Details of
Function
−
−
If an internal reset signal is generated in the POC circuit, the reset control flag
register (RESF) is cleared to 00H.
In a system where the supply voltage (V
vicinity of the POC detection voltage (V
and released from the reset status. In this case, the time from release of reset to
the start of the operation of the microcontroller can be arbitrarily set by taking the
following action.
To stop LVI, follow either of the procedures below.
• When using 8-bit memory manipulation instruction: Write 00H to LVIM.
• When using 1-bit memory manipulation instruction: Clear LVION to 0 first and
Be sure to clear bits 3 to 7 to 0.
<1> must always be executed. When LVIMK = 0, an interrupt may occur
immediately after the processing in <5>.
If “POC used” is selected by a mask option, procedures <3> and <4> are not
required.
If supply voltage (V
internal reset signal is not generated.
If “POC used” is selected by a mask option, procedures <3> and <4> are not
required.
In a system where the supply voltage (V
vicinity of the LVI detection voltage (V
how the low-voltage detector is used.
(1) When used as reset
The system may be repeatedly reset and released from the reset status.
In this case, the time from release of reset to the start of the operation of the
microcontroller can be arbitrarily set by taking action (a) below.
(2) When used as interrupt
Interrupt requests may be frequently generated. Take action (b) below.
Directly connect the REGC pin of standard products and (A) grade products to V
when the regulator is not used.
The regulator cannot be used with (A1) and (A2) grade products. Be sure to
connect the REGC pin of these products directly to V
There are differences in noise immunity and noise radiation between the flash
memory and mask ROM versions. When pre-producing an application set with
the flash memory version and then mass-producing it with the mask ROM version,
be sure to conduct sufficient evaluations for the commercial samples (not
engineering samples) of the mask ROM versions.
The initial value of IMS is CFH. Be sure to set the value of the relevant mask
ROM version at initialization.
When using a mask ROM version, be sure to set the value indicated in Table 28-2
to IMS.
The initial value of IXS is 0CH. Be sure to set the value of the relevant mask
ROM version at initialization.
When using a mask ROM version, be sure to set the value indicated in Table 28-3
to IXS.
APPENDIX D LIST OF CAUTIONS
User’s Manual U15947EJ3V1UD
DD
) > detection voltage (V
Cautions
LVI
POC
), the operation is as follows depending on
DD
DD
) fluctuates for a certain period in the
) fluctuates for a certain period in the
), the system may be repeatedly reset
LVI
) when LVIMD is set to 1, an
DD
then clear LVIE to 0.
.
DD
p. 467
p. 469
p. 473
p. 474
p. 475
p. 475
p. 475
p. 477
p. 479
p. 483
p. 483
p. 486
p. 487
p. 487
p. 488
p. 488
Page
(21/23)
659