Datasheet

Section 19 Clock Pulse Generator
Rev.7.00 Dec. 24, 2008 Page 603 of 698
REJ09B0074-0700
19.6 Subclock Oscillator
19.6.1 Connecting 32.768-kHz Crystal Resonator
supply a clock to the subclock divider, connect a 32.768-kHz crystal resonator, as shown in figure
19.6. Figure 19.7 shows the equivalence circuit for a 32.768-kHz oscillator.
OSC1
OSC2
Note: C
1
and C
2
are reference values including the floating
capacitance of the board.
C
1
C
2
C
1
= C
2
= 15 pF (typ.)
Figure 19.6 Example Connection of 32.768-kHz Quartz Oscillator
OSC1 OSC2
CsLs Rs
Co
Co = 1.5 pF (typ.)
Rs = 14 kΩ (typ.)
fw = 32.768 kHz
Type name = C001R (SEIKO EPSON)
Figure 19.7 Equivalence Circuit for 32.768-kHz Oscillator
19.6.2 Handling Pins when Subclock Not Required
If no subclock is required, connect the OSC1 pin to Vss and leave OSC2 open, as shown in figure
19.8. Set the SUBSTP bit of LPWRCR to 1. If this setting is not made, transition to power-down
mode may not complete properly in some cases.
OSC1
OSC2
Open stat
e
Figure 19.8 Pin Handling when Subclock Not Required