Driving LPC1500 with EPSON Crystals

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Driving LPC1500 with EPSON Crystals
Rev. 1.0 — 06 October 2015
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Document information
Info
Content
Keywords
LPC15xx, RTC, Crystal, Oscillator
Abstract
Characterization results of EPSON crystals with LPC15xx MHz and
(RTC) 32.768 kHz Oscillator.
R_10075
NXP Semiconductors
Driving LPC1500 with EPSON Crystals
Revision history
Rev
Date
1.0
20151006
Description
Initial version
Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
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All information provided in this document is subject to legal disclaimers.
Rev. 1.0 — 06 October 2015
© NXP B.V.2015. All rights reserved.
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Driving LPC1500 with EPSON Crystals
1. Introduction
The LPC15xx series are Cortex-M3 based MCUs running at speeds up to 72MHz.
This microcontroller family supports four different clock sources: internal IRC oscillator,
watchdog oscillator, crystal (MHz) oscillator, and 32.768 kHz (RTC) oscillator. The
nominal IRC frequency is 12 MHz. Upon power-up or any chip reset, the LPC15xx starts
up with IRC as the clock source. Software may later switch to one of the other available
clock sources.
We have evaluated/characterized EPSON make 12 MHz and 32.768 kHz (RTC) crystals
with LPC15xx and the results/recommendations are given below.
2. Characterization results
2.1 MHz oscillator circuit
Fig 1.
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MHz oscillator circuit
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2.2 MHz recommended crystals and external components
Based on the characterization results, following crystals and external components are
recommended for LPC15xx series microcontrollers. Note that equivalent crystals from
other manufacturers can also be used instead.
Table 1.
Recommended crystals and external components
Product Product Code
Frequency
CL
External Components Drive Level |-R|
Name
[MHz]
[pF]
Cd [pF]
FA-238V Q22FA23V00019**
12
10
7
FA-238V Q22FA23V00007**
12
12
FA-20H
12
10
Q24FA20H00152**
Cg [pF]
[uW]
[Ω]
7
37
2490
10
10
49
1890
7
7
69
2490
2.3 RTC oscillator circuit
Fig 2.
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kHz (RTC) oscillator circuit
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Driving LPC1500 with EPSON Crystals
2.4 RTC recommended crystals and external components
Table 2.
Recommended crystals and external components
Product Product Code
Frequency
CL
External Components Drive Level |-R|
Name
[kHz]
[pF]
Cg [pF]
Cd [pF]
[uW]
[kΩ]
FC-135
Q13FC13500004**
32.768
12.5
22
18
0.11
560
MC-146
Q13MC14620002** 32.768
12.5
22
18
0.13
560
Notes:
1. Above recommendations are based on the actual evaluation results and solely
intended to help users in picking the right components.
2. Note that these results are based on a particular hardware board (design) and a
particular LPC MCU sample. Therefore, it does not cater to part to part variation,
be it MCU or the external components.
3. As the actual board layout (design) and choice of external components greatly
influences the best suitable crystal load capacitance, we do not assume any
responsibility and grant warranty for above recommendations.
4. It is always recommended that the end users evaluate their own designs to
ensure the best performance desired.
For more information on these crystals and guidelines, please visit the EPSON website.
http://www5.epsondevice.com/en/ic_partners/nxp/lpc1x.html
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3. Legal information
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All information provided in this document is subject to legal disclaimers.
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Driving LPC1500 with EPSON Crystals
4. Contents
1.
2.
2.1
2.2
2.3
2.4
3.
3.1
3.2
3.3
4.
Introduction ......................................................... 3
Characterization Results .................................... 3
MHz Oscillator Circuit ......................................... 3
MHz Recommended Crystals and External
Components ....................................................... 4
RTC Oscillator Circuit ......................................... 4
RTC Recommended Crystals and External
Components ....................................................... 5
Legal information ................................................ 6
Definitions .......................................................... 6
Disclaimers......................................................... 6
Trademarks ........................................................ 6
Contents ............................................................... 7
Please be aware that important notices concerning this document and the product(s)
described herein, have been included in the section 'Legal information'.
© NXP B.V. 2015.
All rights reserved.
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
Date of release: 06 October 2015
Document identifier: R_10075