PCF8523TS View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
'PCF8523TS' PDF : 74 Pages View PDF
NXP Semiconductors
PCF8523
Real-Time Clock (RTC) and calendar
8.9.1 Timer registers
8.9.1.1 Register Tmr_CLKOUT_ctrl and clock output
Table 34. Tmr_CLKOUT_ctrl - timer and CLKOUT control register (address 0Fh) bit
description
Bit
Symbol
Value
Description
7
TAM
0[1]
permanent active interrupt for timer A and for
the second interrupt timer
1
pulsed interrupt for timer A and the second
interrupt timer
6
TBM
0[1]
permanent active interrupt for timer B
1
pulsed interrupt for timer B
5 to 3 COF[2:0]
see Table 35 CLKOUT frequency selection
2 to 1 TAC[1:0]
00[1] to 11
timer A is disabled
01
timer A is configured as countdown timer
if CTAIE (register Control_2) is set logic 1, the
interrupt is activated when the countdown
timed out
10
timer A is configured as watchdog timer
if WTAIE (register Control_2) is set logic 1,
the interrupt is activated when timed out
0
TBC
0[1]
timer B is disabled
1
timer B is enabled
if CTBIE (register Control_2) is set logic 1, the
interrupt is activated when the countdown
timed out
[1] Default value.
8.9.1.2 CLKOUT frequency selection
Clock output operation is controlled by the COF[2:0] in the Tmr_CLKOUT_ctrl register.
Frequencies of 32.768 kHz (default) down to 1 Hz can be generated (see Table 35) for
use as a system clock, microcontroller clock, input to a charge pump, or for calibration of
the oscillator.
A programmable square wave is available at pin INT1/CLKOUT and pin CLKOUT, which
are both open-drain outputs. Pin INT1/CLKOUT has both functions of INT1 and CLKOUT
combined.
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 STOP is active, the INT1/CLKOUT and CLKOUT pins are
high-impedance for all frequencies except of 32.768 kHz, 16.384 kHz and 8.192 kHz. For
more details, see Section 8.10.
PCF8523
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 7 — 28 April 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
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