S-35730C01A-K8T2U Datasheet, PDF (13/20 Pages) Seiko Instruments Inc – CONVENIENCE TIMER

FOR AUTOMOTIVE 125°C OPERATION CLOCK PULSE OUTPUT WITH FREQUENCY SETTING PIN CONVENIENCE TIMER
Rev.1.1_00
S-35730 Series
 Configuration of Crystal Oscillation Circuit
Since the S-35730 Series has built-in capacitors (C_g and C_d), adjustment of oscillation frequency is unnecessary.
However, the crystal oscillation circuit is sensitive to external noise and parasitic capacitance (C_P), these effects may
become a factor to worsen the clock accuracy. Therefore, the following steps are recommended for optimizing the
configuration of the crystal oscillation circuit.
• Locate the bypass capacitor adjacent to the power supply pin of the S-35730 Series.
• Place the S-35730 Series and the crystal oscillator as close to each other as possible, and shorten the wiring.
• Increase the insulation resistance between pins and the board wiring patterns of XIN and XOUT.
• Do not place any signal or power lines close to the crystal oscillation circuit.
• Locate the GND layer immediately below the crystal oscillation circuit.
(In the case of a multi-layer board, only the layer farthest from the oscillation circuit should be located as the GND layer.
Do not locate a circuit pattern on the intermediate layers.)
Crystal oscillator: 32.768 kHz ^S-35730
C_L = 6.0 pF to 9.0 pF
XIN
C_g
Parasitic
capacitance (C_P)
C_d
XOUT
R_f
R_d
R_f = 100 MΩ
R_d = 100 kΩ
Figure 13 Configuration of Crystal Oscillation Circuit
Locate the GND layer in the
layer immediately below
(In the case of a multi-layer board, only the layer
farthest from the crystal oscillation circuit
should be located as the GND layer.
Do not locate a circuit pattern on the
intermediate layers.)
Crystal
oscill ator
XOUT
XIN
VSS
S-35730
Top view
Shield the perimeter with GND
Figure 14 Example of Recommended Connection Pattern Diagram
Caution 1. Oscillation characteristics are subject to the variation of each component such as board parasitic
capacitance, parasitic resistance, crystal oscillator and external capacitor. When configuring the
crystal oscillation circuit, pay sufficient attention for them.
2. When using the product in automobile equipment, select the components which can be
automobile carried for each component such as crystal oscillator, external capacitor and board.
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