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CHAPTER 22 POWER-ON-CLEAR CIRCUIT
User’s Manual U19780EJ2V0UD
563
22.2 Configuration of Power-on-Clear Circuit
The block diagram of the power-on-clear circuit is shown in Figure 22-1.
Figure 22-1. Block Diagram of Power-on-Clear Circuit
−
+
Reference
voltage
source
Internal reset signal
V
DD
V
DD
22.3 Operation of Power-on-Clear Circuit
(1) In 1.59 V POC mode (option byte: POCMODE = 0)
•
An internal reset signal is generated on power application. When the supply voltage (V
DD
) exceeds the
detection voltage (V
POC
= 1.59 V
±
0.15 V), the reset status is released.
•
The supply voltage (V
DD
) and detection voltage (V
POC
= 1.59 V
±
0.15 V) are compared. When V
DD
< V
POC
, the
internal reset signal is generated. It is released when V
DD
≥
V
POC
.
(2) In 2.7 V/1.59 V POC mode (option byte: POCMODE = 1)
•
An internal reset signal is generated on power application. When the supply voltage (V
DD
) exceeds the
detection voltage (V
DDPOC
= 2.7 V
±
0.2 V), the reset status is released.
•
The supply voltage (V
DD
) and detection voltage (V
POC
= 1.59 V
±
0.15 V) are compared. When V
DD
< V
POC
, the
internal reset signal is generated. It is released when V
DD
≥
V
DDPOC
.
The timing of generation of the internal reset signal by the power-on-clear circuit and low-voltage detector is
shown below.