UPD4991ACX Renesas Electronics America, UPD4991ACX Datasheet - Page 30

• Manufacturer Part Number: UPD4991ACX
• Manufacturer: Renesas Electronics America

Specifications of UPD4991ACX

• Lead Free Status / RoHS Status: Supplier Unconfirmed

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(d) BUSY signal
(e) Alarm flag with auto reset
This is the count flag of the time counter. A carry occurs in the time counter 457.7 s after the BUSY signal
has risen. If the value of the time counter is read while a carry occurs, the correct value may not
be read. For details, refer to CHAPTER 3 ACCESS PROCEDURE.
Internal time counter
When alarm coincidence occurs, the PD4991A sets the ALARM FLAG and outputs an alarm signal to
TP1. When alarm no longer coincides with the value of the time counter, and if the alarm coincidence
with auto reset function is selected, the PD4991A resets the ALARM FLAG and stops output from TP1
(restores to the H level).
If the alarm coincidence with auto reset function is not selected, TP1 output is not stopped. To stop it,
write 0 to the ALARM FLAG of CONTROL REGISTER 2. This operation is illustrated in Figure 2-9.
TP1 TP2
1 Hz
BUSY FLAG "1"
457.7 s
CHAPTER 2 OPERATIONS
Figure 2-8. BUSY Signal
Carry
30.5 s
BUSY FLAG "0"