Datasheet

Section 20 Band-Gap Regulator, Power-On Reset (Optional), and Low-Voltage Detection Circuits (Optional)
Rev. 1.50 Sep. 18, 2007 Page 460 of 584
REJ09B0240-0150
20.1 Features
• BGR circuit
Supplies stable reference voltage covering the entire operating voltage range and the operating
temperature range.
• Power-on reset circuit
Uses an external capacitor to generate an internal reset signal when power is first supplied.
• Low-voltage detection circuit
LVDR: Monitors the power-supply voltage, and generates an internal reset signal when the
voltage falls below a specified value.
LVDI: Monitors the power-supply voltage, and generates an interrupt when the voltage falls
below or rises above respective specified values.
Two pairs of detection levels for reset generation voltage are available: when only the LVDR
circuit is used, or when the LVDI and LVDR circuits are both used.
[Legend]
Vcc: Power supply
VCL: Internal power supply generated from Vcc by the step-down circuit
VBGR: Reference voltage from BGR
VCLSEL: Select signal for the source of the on-chip oscillator power supply
RCSTP: On-chip oscillator stop signal
Step-down circuit
On-chip
oscillator
LVD (low-voltage
detection circuit)
Vcc
VCL
VBGR
VCLSEL
RCSTP
BGR
Figure 20.1 Block Diagram around BGR