LC872G08A/06A/04A

No.A1400-10/27

Recommended Unused Pin Connections

Recommended Unused Pin Connections

Port Name

Board

Software

P00 to P07

Open

Output low

P10 to P17

Open

Output low

P20 to P21

Open

Output low

P70

Open

Output low

CF1/XT1

Pulled low with a 100k

Ω resistor or less

General-purpose input port

CF2/XT2

Pulled low with a 100k

Ω resistor or less

General-purpose input port

Notes on CF1/XT1 and CF2/XT2 pins

• When using as general-purpose input ports

Since the CF1/XT1 and CF2/XT2 pins are configured as CF oscillator pins at system reset time, it is necessary to

add a current limiting resistor of 1k

Ω or greater to the CF2/XT2 pin in series when using them as general-purpose

input pins.

• Differences between flash and mask ROM version

System Reset Time State

After System Reset is Released

CF1/XT1

Set high via the internal Rf resistor

CF oscillation state

Flash ROM version

LC87F2G08A

CF2/XT2

Set high

CF oscillation state

CF1/XT1

Set low via the internal Rf resistor

CF oscillation state

Mask ROM version

LC872G08A/06A/04A

CF2/XT2

Set low

CF oscillation state

Power Pin Treatment Recommendations (VDD1, VSS1)

Connect bypass capacitors that meet the following conditions between the VDD1 and VSS1 pins:

• Connect among the VDD1 and VSS1 pins and bypass capacitors C1 and C2 with the shortest possible heavy lead

wires, making sure that the impedances between the both pins and the bypass capacitors are as equal as possible

(L1=L1’, L2=L2’).

• Connect a large-capacity capacitor C1 and a small-capacity capacitor C2 in parallel.

The capacitance of C2 should be approximately 0.1

μF.

VSS1

VDD1

L1’

L2’

L1

L2

C1

C2