For customers using LPC1xxxx from NXP Semiconductors

We are pleased to introduce you to our crystal unit

Crystal Recommendations for NXP Semiconductors "LPC1xxxx 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
Please refer to our web site:
http://www5.epsondevice.com/en/information/precaution/design.html
Support information > Precautions in Designing oscillation circuits > 2. Allowance for oscillation

Drive Level:
You need to confirm if oscillation is stable, and if the drive level is within the specification.
Please refer to our web site:
http://www5.epsondevice.com/en/information/precaution/design.html
Support information > Precautions in Designing oscillation circuits > 1. Drive level

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.
Please refer to our web site:
http://www5.epsondevice.com/en/information/precaution/design.html
Support information > Precautions in Designing oscillation circuits > 3. Load capacitance

* 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.

Selection Guidance for crystal unit

Epson Crystal Product Lineups

Product Size [mm] Applications Images
MC-146 7×1.5×1.4t DSC, Consumer equipment, Radio equipment, Blood pressure meter, Blood-sugar monitor, Security systems
MC146
FC-135
FC-135R

3.2×1.5×0.8t
PMP, DSC, Portable equipment
FC135
FA-238
FA-238V
3.2×2.5×0.7t -Mobile phone,Bluetooth,W-LAN
-ISM band,Clock for MPU
FA238.A233V
FA-20H 2.5×2.0×0.55t
FA-20H

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

LPC15xx

1) 32kHz

LPC1549


Product
name
Frequency
[Hz]
CL*1
[pF]
Product
Code*2
External parts *3 Drive
Level
[μW]
Package
size[mm]
WxDxH
Cg
[pF]
Cd
[pF]
FC-135
32.768k
12.5
22
18
0.11
3.2x1.5x0.8
MC-146
32.768k
12.5
22
18
0.13
7.0x1.5x1.4

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

2) 12MHz

LPC1549


Product
name
Frequency
[Hz]
CL*1
[pF]
Product
Code*2
External parts *3 Drive
Level
[μW]
Package
size[mm]
WxDxH
Cg
[pF]
Cd
[pF]
FA-238V
12M
10
7
7
37
3.2x1.5x0.7
FA-238V
12M
12
10
10
49
3.2x1.5x0.7
FA-20H
12M
10
7
7
69
2.5x2.0x0.55

LPC11U××

1) 32kHz

LPC11U68


Product
name
Frequency
[Hz]
CL*1
[pF]
Product
Code*2
External parts *3 Drive
Level
[μW]
Package
size[mm]
WxDxH
Cg
[pF]
Cd
[pF]
FC-135
32.768k
12.5
22
18
0.09
3.2x1.5x0.8
MC-146
32.768k
12.5
18
18
0.10
7.0x1.5x1.4

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

2) 12MHz

LPC11U68


Product
name
Frequency
[Hz]
CL*1
[pF]
Product
Code*2
External parts *3 Drive
Level
[μW]
Package
size[mm]
WxDxH
Cg
[pF]
Cd
[pF]
FA-238V
12M
10
7
7
37
3.2x1.5x0.7
FA-238V
12M
12
10
10
49
3.2x1.5x0.7
FA-20H
12M
10
7
7
59
2.5x2.0x0.55


LPC175x, LPC176x,LPC177x,LPC178x,LPC18xx Series

1) 32kHz

F5xx,F6xx


Product
name
Frequency
[Hz]
CL*1
[pF]
Product
Code*2
External parts *3 Drive
Level
[μW]
Package
size[mm]
WxDxH
Cg
[pF]
Cd
[pF]
FC-135
32.768k
12.5
22
22
0.094
3.2x1.5x0.8
MC-146
32.768k
12.5
22
18
0.005
7.0x1.5x1.4

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

2) 12MHz

F5xx,F6xx


Product
name
Frequency
[Hz]
CL*1
[pF]
Product
Code*2
External parts *3 Drive
Level
[μW]
Package
size[mm]
WxDxH
Cg
[pF]
Cd
[pF]
Rf*4
[Ω]
FA-238V
12M
10
10
10
1M
45
3.2x2.5x0.7

LPC111x

1) 12MHz,16MHz

F5xx,F6xx


Product
name
Frequency
[Hz]
CL*1
[pF]
Product
Code*2
External parts *3 Drive
Level
[μW]
Package
size[mm]
WxDxH
Cg
[pF]
Cd
[pF]
Rf*4
[Ω]
Rd
[Ω]
FA-238V
12M
10
12
12
1M
-
44
3.2x2.5x0.7
FA-238
16M
10
18
15
1M
470
72
3.2x2.5x0.7

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.

TOP View
For 32kHZ 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.
Cross-seection View(Multi-layered PCB Board)

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