UPD4991AGS Renesas Electronics America, UPD4991AGS Datasheet - Page 44

• Manufacturer Part Number: UPD4991AGS
• Manufacturer: Renesas Electronics America

Specifications of UPD4991AGS

• Lead Free Status / RoHS Status: Supplier Unconfirmed

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(3) Using CLK WAIT/CLK START command
By using the CLK control command of the CONTROL REGISTER 1, disable the carry from occurring while
the time data is read.
Time is not delayed if the CLK START command is issued within 0.5 seconds after the CLK WAIT command
is issued. Figure 3-5 shows this procedure.
This method is supported only by the PD4991A in NEC’s real-time clock IC series.
Figure 3-5. Reading Time with CLK WAIT/CLK START
BASIC TIME MODE
Time reading
CLK START
CLK WAIT
routine
Select
Start
End
CHAPTER 3 ACCESS PROCEDURE
Addresses 0D
Address 0F
Read addresses 0
Address 0D
H
H
H
through 08
0
0
H
H
H
or 3
through 0C
H
H
H