We are pleased to introduce you to our crystal unit for RX600, RX700 Series.
Please refer to Renesas RX600, RX700 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 RX600, RX700 series.
· Precautions for designing of PCB Board
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.
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.
Product
Size [mm]
Applications
Images
SM146
7×1.5×0.8t
DSC, Consumer equipment,
Radio equipment, Blood pressure meter,
Blood-sugar monitor, Security systems
RX600, RX700 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 RX600, RX700 Series Design Guide for Sub-Clock Circuits.
· *1 Load Capacitance
· *2 Two digits of the product code is packing specification, please click here for more detail.
· *3 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.
-Please lay out crystal unit, capacitor and resistor near RX600, RX700 Series as far as possible.
-Please connect pins within 20mm length, and do not cross other signal lines.
-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.
