PCF8563TF4 NXP Semiconductors, PCF8563TF4 Datasheet - Page 25

• Manufacturer Part Number: PCF8563TF4
• Manufacturer: NXP Semiconductors

Specifications of PCF8563TF4

• Bus Type: Serial (2-Wire, I2C)
• Operating Supply Voltage (typ): 2.5/3.3/5V
• Package Type: SO
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 1.8V
• Operating Temperature Classification: Industrial
• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Pin Count: 8
• Mounting: Surface Mount
• Date Format: DW:DM:M:Y
• Time Format: HH:MM:SS
• Lead Free Status / RoHS Status: Compliant

NXP Semiconductors
PCF8563
Product data sheet
9.6 Interface watchdog timer
During read/write operations, the time counting circuits are frozen. To prevent a situation
where the accessing device becomes locked and does not clear the interface, the
PCF8563 has a built in watchdog timer. Should the interface be active for more than 1 s
from the time a valid slave address is transmitted, then the PCF8563 will automatically
clear the interface and allow the time counting circuits to continue counting. The watchdog
will trigger between 1 s and 2 s after receiving a valid slave address. Each time the
watchdog period is exceeded, 1 s will be lost from the time counters.
The watchdog is implemented to prevent the excessive loss of time due to interface
access failure e.g. if main power is removed from a battery backed-up system during an
interface access.
Fig 22. Interface watchdog timer
a. Correct data transfer: read or write
b. Incorrect data transfer; read or write
WD timer
WD timer
counters
counters
data
data
time
time
All information provided in this document is subject to legal disclaimers.
START
START
Rev. 8 — 18 November 2010
SLAVE ADDRESS
SLAVE ADDRESS
running
running
DATA
DATA
time counters frozen
WD timer tracking
time counters frozen
WD timer tracking
DATA
DATA
t < 1 s
1 s < t < 2 s
data transfer fail
STOP
Real-time clock/calendar
running
PCF8563
© NXP B.V. 2010. All rights reserved.
WD trips
running
013aaa420
013aaa421
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