RX200 Series

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For customers designing Renesas "RX200 Series"

We are pleased to introduce you to our crystal unit for RX200 Series. 
Please refer to Renesas RX200 Series Design Guide for Sub-Clock Circuits.
· Items to Confirm (designing of oscillation circuit)
· Selection Guidance for crystal unit
· Crystal Products Lineup
· Oscillation Circuit and Selection Guidance of Crystal Unit for RX200 series.
· Precautions for designing of PCB Board

Items to Confirm (designing of oscillation circuit)

Please note: to design oscillation circuit, you need to confirm the electronic characteristics as follows:

Oscillation allowance and Negative resistance (-R):
You need to confirm oscillation capability.
We recommend the condition: (-R) / ESR > 5
* -R: Negative resistance, ESR: Equivalent Series Resistance

Drive Level:
You need to confirm if oscillation is stable, and if the drive level is within the specification.

Load Capacitance:
Load capacitance affects frequency stability, oscillation allowance, negative resistance, and start-up time of oscillation.
In addition the load capacitance is determinative factor of crystal unit's load capacitance (CL value) directly.
* frequency stability: frequency deviation out of circuit conditions.

Selection Guidance for crystal unit

When Customer selects crystal unit, load capacitance (CL value) is an important factor of the selection.
For instance, crystal with small CL(7.0 pF) makes larger oscillation allowance, smaller current consumption and worse frequency stability, like below table.
Oppositely, crystal with large CL(12.5 pF) makes smaller oscillation allowance, larger current consumption and better frequency stability.
Please select it in consideration of these characteristics.

StrongFirst Crystal Product Lineups

Product	Size [mm]	Applications	Images
SM146	7×1.5×0.8t	DSC, Consumer equipment, Radio equipment, Blood pressure meter, Blood-sugar monitor, Security systems

Oscillation Circuit and Selection Guidance of Crystal Unit for RX200 Series

RX200 Series Sub-Clock Oscillation Mode	StrongFirst Crystal unit				External parts *3		Oscillation Stabilization Time [sec]	Negative Resistance [kΩ]
	Product	Frequency [Hz]	CL *1 [pF]	Part number*2	Cg [pF]	Cd [pF]
Standard CL drive capacity	SM146	32.768k	7	SM146-32.768K-7-20-E	9	9	1.15	-1000
Low CL drive capacity	SM146	32.768k	3.7	Go to Low CL Page	3	3	1	-510

Please refer to Renesas RX200 Series Design Guide for Sub-Clock Circuits.

Notes:

· *1 Load Capacitance

· *2 Above recommendations are based on actual evaluation results and intended to support users in picking the right components. And the results are only according to the sample set that received from our customers, so it is not including the dispersion trend of IC and the external parts.
As the actual board layout and choice of external components influences the best suitable crystal load capacitance, We do not assume any responsibility and grant warranty for above recommendations. Users design must be verified and decided by own and individual evaluation.

Precautions for designing of PCB Board

Layout of pins, Crystal unit, Capacitor and Resistor

-Please lay out crystal unit, capacitor and resistor near RX200 Series as far as possible.
-Please connect pins within 20mm length, and do not cross other signal lines.

GND Line Pattern and Interconnection of PCB

-Please lay out GND line pattern under crystal unit.
-In case of multi-layer PCB board, do not lay out other signal lines under crystal unit.

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