UPD4991ACX Renesas Electronics America, UPD4991ACX Datasheet - Page 49

• Manufacturer Part Number: UPD4991ACX
• Manufacturer: Renesas Electronics America

Specifications of UPD4991ACX

• Lead Free Status / RoHS Status: Supplier Unconfirmed

4.1 Crystal Oscillation Circuit
oscillation stabilization resistor R
and C
it may be).
much difference in terms of characteristics.
unstable, and the accuracy of the watch may be affected by external noise.
4.2 Oscillation Characteristics and Accuracy
oscillation frequency changes by 100 ppm from 32.768 kHz, the watch accuracy is accordingly changed by 100 ppm.
The oscillation frequency changes with the load capacitance, temperature, and supply voltage.
The
Figure 4-1 shows the equivalent circuit. The oscillation frequency is determined by external load capacitances C
Because X
Connect point A in Figure 4-1 to V
Keep the wiring of the crystal resonator as short as possible. If the wiring length is too long, oscillation may be
The accuracy of the watch is always determined by the accuracy of the oscillation frequency. If the
The dependencies of the oscillation frequency on these parameters are explained below.
D
, and crystal resonator.
PD4991A has an oscillation circuit consisting of one CMOS inverter stage, feedback resistor R
IN
and X
CHAPTER 4 ELECTRICAL SPECIFICATIONS AND INTERFACE
OUT
has stray capacitance in addition to C
X
C
Figure 4-1. Crystal Oscillation Circuit of PD4991A
IN
G
D
.
DD
or V
R
X
f
SS
of the PD4991A. Whether it is connected to V
A
R
X
C
D
OUT
D
V
DD
or V
G
SS
X : 32.768 kHz
and C
To 15-stage divider
D
, either C
G
or C
D
must be adjusted (whichever
DD
or V
SS
does not make
f
, and
47
G