US38024-BAG1 Renesas Electronics America, US38024-BAG1 Datasheet - Page 466

• Manufacturer Part Number: US38024-BAG1
• Description: DEV EVALUATION KIT H8/38024
• Manufacturer: Renesas Electronics America
• Series: H8®r
• Type: MCUr

Specifications of US38024-BAG1

• Contents: 2G (Second-generation) Evaluation Board, HEW debugger support, Cable and CD-ROM
• For Use With/related Products: H8/38024
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Section 14 Power-On Reset and Low-Voltage Detection Circuits (H8/38124 Group Only)
Figure 14.6 shows a usage example for the LVD function employing pins Vref, extD, and extU.
Below is an explanation of the method for calculating the external resistor values when using the
Vref, extD, and extU pins for input of reference and detection voltages from sources external to
the LSI.
Procedure:
1. First, determine the overall resistance value, R. The current consumed by the resistor is
2. Determine the power supply drop detection voltage (Vint(D) and the power supply rise
3. Using a resistance value calculation table like the one shown below, plug in values for R,
Rev. 8.00 Mar. 09, 2010 Page 444 of 658
REJ09B0042-0800
R1 =
517 kΩ
R2 =
33 kΩ
R3 =
450 kΩ
External power
supply voltage
determined by the value of R. A lower R will result in a greater current flow, and a higher R
will result in a reduced current flow. The value of R is dependent on the configuration of the
system in which the LSI is installed.
detection voltage (Vint(U).
Vreset1, Vint(D), and Vint(U) to calculate the values of Vref, R1, R2, and R3.
External reference
Figure 14.6 LVD Function Usage Example Employing Pins Vref, extD, and extU
voltage 1.3 V
Setting conditions:
• Vref = 1.3 V external input (This Vref value results in a Vreset value of 2.5 V.)
• Power supply drop detection voltage input of 2.7 V from extD
• Power supply rise detection voltage input of 2.9 V from extU
• 1 MΩ variable resistor connected externally
extD
extU
Vref
On-chip
ladder
resistor
R1
R2
D1
U1
U2
D2
On-chip reference
voltage generator
+
−
+
−
LVDRES
LVDINT
controller
Interrupt
LVDCR
LVDSR
Interrupt
request