PCF85063TP All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2015. All rights reserved.
Product data sheet Rev. 4 — 6 May 2015 12 of 52
NXP Semiconductors
PCF85063TP
Tiny Real-Time Clock/calendar
The duration of the timer is affected by the register Offset (see Section 8.2.3). Only when
OFFSET[6:0] has the value 00h the periods are consistent.
8.2.2.2 TF: timer flag
The timer flag (bit TF) is set logic 1 on the first trigger of MI or HMI and remains set until it
is cleared by command.
8.2.2.3 COF[2:0]: Clock output frequency
A programmable square wave is available at pin CLKOUT. Operation is controlled by the
COF[2:0] bits in the register Control_2. Frequencies of 32.768 kHz (default) down to 1 Hz
can be generated for use as a system clock, microcontroller clock, input to a charge
pump, or for calibration of the oscillator.
Pin CLKOUT is a push-pull output and enabled at power-on. CLKOUT can be disabled by
setting COF[2:0] to 111. When disabled, the CLKOUT is LOW.
The duty cycle of the selected clock is not controlled but due to the nature of the clock
generation, all clock frequencies except 32.768 kHz have a duty cycle of 50 : 50.
The STOP bit function can also affect the CLKOUT signal, depending on the selected
frequency. When the STOP bit is set logic 1, the CLKOUT pin generates a continuous
LOW for those frequencies that can be stopped. For more details of the STOP bit function,
see Section 8.2.1.2
.
[1] Duty cycle definition: % HIGH-level time : % LOW-level time.
[2] Default value.
[3] 1 Hz clock pulses are affected by offset correction pulses.
Table 10. Effect of bits MI and HMI on INT generation
Minute interrupt (bit MI) Half minute interrupt (bit HMI) Result
0 0 no interrupt generated
1 0 an interrupt every minute
0 1 an interrupt every 30 s
1 1 an interrupt every 30 s
Table 11. CLKOUT frequency selection
COF[2:0] CLKOUT frequency (Hz) Typical duty cycle
[1]
Effect of STOP bit
000
[2]
32768 60 : 40 to 40 : 60 no effect
001 16384 50 : 50 no effect
010 8192 50 : 50 no effect
011 4096 50 : 50 CLKOUT = LOW
100 2048 50 : 50 CLKOUT = LOW
101 1024 50 : 50 CLKOUT = LOW
110 1
[3]
50 : 50 CLKOUT = LOW
111 CLKOUT = LOW - -
