i.MX 6 Family

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For customers designing NXP Semiconductors

We are pleased to introduce you to our crystal unit

· Items to Confirm (designing of oscillation circuit)
· Selection Guidance for crystal unit
· Crystal Products Lineup
· Oscillation Circuit and Selection Guidance of Crystal Unit.
· Precautions for designing of PCB Board
Crystal Recommendations for NXP Semiconductors “i.MX 6 Families”.
· Recommendations i.MX 6 Family.

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, ｌload 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.

Epson Crystal Product Lineups

Oscillation Circuit and Selection Guidance of Crystal Unit for i.MX Application processor

i.MX 6Quad, 6Dual, 6DualLite, 6Solo

32kHz Crystal

Pin number of RTC_XTALI/RTC_XTALO

21x21mm BGA

24MHz Crystal

Pin number of XTALI/XTALO

21x21mm BGA

Notes:*

1. Load capacitance.

2. Frequency tolerance (standard)

3. Above recommendations are based on actual evaluation results and intended to support users in picking the right components.
As the actual board layout and choice of external components influences the best suitable crystal load capacitance, We does not assume any responsibility and grant warranty for above recommendations.
Users design must be verified and decided by own and individual evaluation.

4. Please evaluate a crystal oscillator without an external feedback resistor Rf if you need. It is possible that a crystal oscillator works without it because i.MX 6 series has an internal feedback resistor Rf in the MHz oscillator.

Precautions for designing of PCB Board

-Please lay out crystal unit, capacitor and resistor near i.MX 6 as far as possible.
-The length of signal patterns in oscillation circuit should be as short as possible, and do not cross other signal lines.

For 32kHZ Crystal Unit

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

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