HD64336900G Datasheet, PDF (295/408 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Tiny Series

Section 17 Band-Gap Circuit, Power-On Reset, and
Low-Voltage Detection Circuits
This LSI can include a band-gap circuit (BGR, band-gap regulator), a power-on reset circuit and
low-voltage detection circuit.
BGR supplies a reference voltage to the internal RC oscillator and low-voltage detection circuit.
Figure 17.1 shows the block diagram of how BGR is allocated.
The low-voltage detection (LVD) circuit consists of two circuits: LVDI (interrupt by low voltage
detection) and LVDR (reset by low voltage detection) circuits.
This circuit is used to prevent abnormal operation (program runaway) from occurring due to the
power supply voltage fall and to recreate the state before the power supply voltage fall when the
power supply voltage rises again.
Even if the power supply voltage falls, the unstable state when the power supply voltage falls
below the guaranteed operating voltage can be removed by entering standby mode when
exceeding the guaranteed operating voltage and during normal operation. Thus, system stability
can be improved. If the power supply voltage falls more, the reset state is automatically entered. If
the power supply voltage rises again, the reset state is held for a specified period, then active mode
is automatically entered.
Figure 17.2 is a block diagram of the power-on reset circuit and the low-voltage detection circuit.
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Rev. 1.00, 11/03, page 267 of 376