For customers using NXP Semiconductors "LPC1xxxx series"

Contents

We are pleased to introduce you to our crystal unit.

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.

For details of each characteristic, please refer to the PDF file.

Precautions for Oscillation Circuit Design PDF

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.

Epson Crystal Product Lineups

Product Size [mm] Applications Images
MC-146 7.0 x 1.5 x 1.4 DSC, Consumer equipment,Radio equipment, Blood pressure meter,Blood-sugar monitor, Security systems MC306
FC-135
FC-135R 		3.2 x 1.5 x 0.9 PMP, DSC, Portable equipment
FA-238
FA-238V 		3.2 x 2.5 x 0.7 -Mobile phone,Bluetooth,W-LAN
-ISM band,Clock for MPU
FA-20H 2.5 x 2.0 x 0.55 FA20H

Oscillation Circuit and Selection Guidance of Crystal Unit for LPCxxxx micro controller

LPC15xx series

1) 32 kHz

Product Name Frequency
[Hz]		 CL*1
[pF]		 Product Code*2 External Parts*3 Drive Level
[µW]		 Package Size
WxDxH
[mm]
Cg
[pF]		 Cd
[pF]
FC-135 32.768k 12.5 Q13FC13500004** 22 18 0.11 3.2 x 1.5 x 0.9
MC-146 32.768k 12.5 Q13MC14620002** 22 18 0.13 7.0 x 1.5 x 1.4

Notes:
Please follow these recommendations and don't use any external capacitors for Cd and Cg below the recommended values.

2) 12 MHz

Product Name Frequency
[Hz]		 CL*1
[pF]		 Product Code*2 External Parts*3 Drive Level
[µW]		 Package Size
WxDxH
[mm]
Cg
[pF]		 Cd
[pF]
FA-238V 12M 10 Q22FA23V00019** 7 7 37 3.2 x 2.5 x 0.7
FA-238V 12M 12 Q22FA23V00007** 10 10 49 3.2 x 2.5 x 0.7
FA-20H 12M 10 Q24FA20H00152** 7 7 69 2.5 x 2.0 x 0.55

LPC11Uxx series

1) 32 kHz

Product Name Frequency
[Hz]		 CL*1
[pF]		 Product Code*2 External Parts*3 Drive Level
[µW]		 Package Size
WxDxH
[mm]
Cg
[pF]		 Cd
[pF]
FC-135 32.768k 12.5 Q13FC13500004** 22 18 0.09 3.2 x 1.5 x 0.9
MC-146 32.768k 12.5 Q13MC14620002** 18 18 0.10 7.0 x 1.5 x 1.4

Notes:
Please follow these recommendations and don't use any external capacitors for Cd and Cg below the recommended values.

2) 12 MHz

Product Name Frequency
[Hz]		 CL*1
[pF]		 Product Code*2 External Parts*3 Drive Level
[µW]		 Package Size
WxDxH
[mm]
Cg
[pF]		 Cd
[pF]
FA-238V 12M 10 Q22FA23V00019** 7 7 34 3.2 x 2.5 x 0.7
FA-238V 12M 12 Q22FA23V00007** 10 10 43 3.2 x 2.5 x 0.7
FA-20H 12M 10 Q24FA20H00152** 7 7 59 2.5 x 2.0 x 0.55

LPC175x, LPC176x, LPC177x, LPC178x, LPC18xx series

1) 32 kHz

Product Name Frequency
[Hz]		 CL*1
[pF]		 Product Code*2 External Parts*3 Drive Level
[µW]		 Package Size
WxDxH
[mm]
Cg
[pF]		 Cd
[pF]
FC-135 32.768k 12.5 Q13FC13500004** 22 22 0.094 3.2 x 1.5 x 0.9
MC-146 32.768k 12.5 Q13MC14620002** 22 18 0.005 7.0 x 1.5 x 1.4

Notes:
Please follow these recommendations and don't use any external capacitors for Cd and Cg below the recommended values.

2) 12 MHz

Product Name Frequency
[Hz]		 CL*1
[pF]		 Product Code*2 External Parts*3 Drive Level
[µW]		 Package Size
WxDxH
[mm]
Cg
[pF]		 Cd
[pF]		 Rf *4
[Ω]
FA-238V 12M 10 Q22FA23V00019** 10 10 1M 45 3.2 x 2.5 x 0.7

LPC111x series

1) 12 MHz, 16 MHz

Product Name Frequency
[Hz]		 CL*1
[pF]		 Product Code*2 External Parts*3 Drive Level
[µW]		 Package Size
WxDxH
[mm]
Cg
[pF]		 Cd
[pF]		 Rf *4
[Ω]		 Rd
[Ω]
FA-238V 12M 10 Q22FA23V00019** 12 12 1M - 44 3.2 x 2.5 x 0.7
FA-238 16M 10 Q22FA23800421** 18 15 1M 470 72 3.2 x 2.5 x 0.7

Notes:*

*1. Load capacitance.
*2. Two digits of the product code is packing specification,please refer here for the 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.
*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 LCP1xxx has an internal feedback resistor Rf in the MHz oscillator.

Precautions for designing of PCB Board

Layout of pins, Crystal unit, Capacitor and Resistor

- Please lay out crystal unit, capacitor and resistor near LPC1xxxx 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 32 kHz Crystal unit

GND Line Pattern and Interconnection of PCB

- 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.