Datasheet
32KX
CK0 CK1CK1
037-038
OR
OR
32kHz
32KXIN
32KXOUT
32-kHz
OSC
IO_1P8
(1.8V)
32KCLKOUT
RTC
037-037
TPS65930/TPS65920
www.ti.com
SWCS037G–MAY 2008–REVISED APRIL 2011
Figure 11-10 shows the 32-kHz square- or sine-wave input clock.
Figure 11-10. 32-kHz Square- or Sine-Wave Input Clock
11.3 Output Clock Specifications
The TPS65920/TPS65930 device provides two output clocks:
• 32KCLKOUT
• HFCLKOUT
11.3.1 32KCLKOUT Output Clock
Figure 11-11 is the block diagram for the 32.768-kHz clock output.
Figure 11-11. 32.768-kHz Clock Output Block Diagram
The TPS65920/TPS65930 device has an internal 32.768-kHz oscillator connected to an external
32.768-kHz crystal through the 32KXIN/32KXOUT balls or an external digital 32.768-kHz clock through the
32KXIN input (see Figure 11-11). The TPS65920/TPS65930 device also generates a 32.768-kHz digital
clock through the 32KCLKOUT pin and can broadcast it externally to the application processor or any
other devices. The 32KCLKOUT clock is broadcast by default in TPS65920/TPS65930 active mode, but
can be disabled if it is not used.
The 32.768-kHz clock (or signal) is also used to clock the RTC embedded in the TPS65920/TPS65930
device. The RTC is not enabled by default. The host processor must set the correct date and time and
enable the RTC functionality.
The 32KCLKOUT output buffer can drive several devices (up to 40-pF load). At startup, 32KCLKOUT
must be stabilized (frequency/duty cycle) before the signal output. Depending on the startup conditions,
this can delay the startup sequence.
Table 11-9 lists the electrical characteristics of the 32KCLKOUT output clock.
Copyright © 2008–2011, Texas Instruments Incorporated Clock Specifications 91
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