HD64F38024HV Datasheet, PDF (464/684 Pages) Renesas Technology Corp – Hardware Manual Renesas 8-Bit Single-Chip Microcomputer H8 Family/H8/300L Super Low Power Series

Section 14 Power-On Reset and Low-Voltage Detection Circuits (H8/38124 Group Only)
When the power-supply voltage does not fall below Vreset1 (typ. = 2.3 V) voltage but rises above
Vint (U) (typ. = 4.0 V) voltage, the LVDI sets the LVDINT signal to 1. If the LVDUE bit is 1 at
this time, the LVDUF bit in LVDSR is set to 1 and an IRQ0 interrupt request is simultaneously
generated.
If the power supply voltage (Vcc) falls below Vreset1 (typ. = 2.3 V) voltage, the LVDR function
is performed.
Vcc
LVDINT
Vint (U)
Vint (D)
Vreset1
VSS
LVDDE
LVDDF
LVDUE
LVDUF
IRQ0 interrupt generated IRQ0 interrupt generated
Figure 14.4 Operational Timing of LVDI Circuit
The reference voltage, power supply voltage drop detection level, and power supply voltage rise
detection level can be input to the LSI from external sources via the Vref, extD, and extU pins.
Figure 14.5 shows the operational timing using input from the Vref, extD, and extU pins.
First, make sure that the voltages input to pins extD and extU are set to higher levels than the
interrupt detection voltage Vexd. After initial settings are made, a power supply drop interrupt is
generated if the extD input voltage drops below Vexd. After a power supply drop interrupt is
generated, if the external power supply voltage rises and the extU input voltage rises higher than
Vexd, a power supply rise interrupt is generated. As with the on-chip circuit, the above function
should be used in conjunction with LVDR (Vreset1) when the LVDI function is used.
Rev. 8.00 Mar. 09, 2010 Page 442 of 658
REJ09B0042-0800