HD64F3687FP Renesas Electronics America, HD64F3687FP Datasheet - Page 400

• Manufacturer Part Number: HD64F3687FP
• Description: IC H8 MCU FLASH 56K 64-LQFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8/300H Tinyr

Specifications of HD64F3687FP

• Core Processor: H8/300H
• Core Size: 16-Bit
• Speed: 20MHz
• Connectivity: I²C, SCI
• Peripherals: PWM, WDT
• Number Of I /o: 45
• Program Memory Size: 56KB (56K x 8)
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 75°C
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

Section 20 Power-On Reset and Low-Voltage Detection Circuits (Optional)
20.3.2
LVDR (Reset by Low Voltage Detect) Circuit:
Figure 20.3 shows the timing of the LVDR function. The LVDR enters the module-standby state
after a power-on reset is canceled. To operate the LVDR, set the LVDE bit in LVDCR to 1, wait
for 50 s (t
stabilized by a software timer, etc., then set the LVDRE bit in LVDCR to 1. After that, the output
settings of ports must be made. To cancel the low-voltage detection circuit, first the LVDRE bit
should be cleared to 0 and then the LVDE bit should be cleared to 0. The LVDE and LVDRE bits
must not be cleared to 0 simultaneously because incorrect operation may occur.
When the power-supply voltage falls below the Vreset voltage (typ. = 2.3 V or 3.6 V), the LVDR
clears the LVDRES signal to 0, and resets the prescaler S. The low-voltage detection reset state
remains in place until a power-on reset is generated. When the power-supply voltage rises above
the Vreset voltage again, the prescaler S starts counting. It counts 131,072 clock ( ) cycles, and
then releases the internal reset signal. In this case, the LVDE, LVDSEL, and LVDRE bits in
LVDCR are not initialized.
Note that if the power supply voltage (Vcc) falls below V
point, the low-voltage detection reset may not occur.
If the power supply voltage (Vcc) falls below Vpor = 100 mV, a power-on reset occurs.
Rev.5.00 Nov. 02, 2005 Page 366 of 500
REJ09B0027-0500
RES
Vcc
PSS-reset
signal
OVF
Internal reset
signal
Low-Voltage Detection Circuit
LVDON
Vpor
t
PWON
) until the reference voltage and the low-voltage-detection power supply have
Figure 20.2 Operational Timing of Power-On Reset Circuit
PSS counter starts
131,072 cycles
Reset released
LVDRmin
= 1.0 V and then rises from that
Vss
Vss