UM10759 - NXP Semiconductors
Contents
1. e Open drain interrupt and clock output pins e Programmable offset register for frequency trimming Fig 2 Block diagram PCF2123 3 Hardware setup 3 1 General requirement for the PCF2123 The RTC circuit just requires one external part the tuning fork quartz as resonator The oscillation capacitors are integrated and therefore there is no need for external load capacitors The quartz crystal must be closely placed to the RTC circuit avoiding long lines which may pick up noise Any tracks with high frequency signals fast edges close to the RTC quartz or quartz interconnect should be avoided The SPl bus interface works up to 8 MHz Supply voltage 1 8 V to 5 5 V The RTC excluding the SPl bus interface however is operating down to as low as 0 9 V It is recommended to have a decoupling capacitor of 100 nF on the Vpp Vssg rails close by UM10759 All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 4 of 14 NXP Semiconductors U M1 0759 Demo board OM13512 for the SPl bus RTC PCF2123 Due to the low power consumption of below 1 uW no precautions for heat dissipations are required even in a sealed housing environment Frequencies of 1 Hz to 32 768 kHz on the CLKOUT pin can be used to measure the frequency for calibration and or for general purpose e g as reference for frequency generation with a PLL A separate2. Data Sheet UM10759 All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 11 of 14 NXP Semiconductors UM10759 8 Legal information Demo board OM13512 for the SPl bus RTC PCF2123 8 1 Definitions Draft The document is a draft version only The content is still under internal review and subject to formal approval which may result in modifications or additions NXP Semiconductors does not give any representations or warranties as to the accuracy or completeness of information included herein and shall have no liability for the consequences of use of such information 8 2 Disclaimers Limited warranty and liability Information in this document is believed to be accurate and reliable However NXP Semiconductors does not give any representations or warranties expressed or implied as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information In no event shall NXP Semiconductors be liable for any indirect incidental punitive special or consequential damages including without limitation lost profits lost savings business interruption costs related to the removal or replacement of any products or rework charges whether or not such damages are based on tort including negligence warranty breach of contract or any other legal theory Notw
3. lower power consumption where the quartzes of 12 5 pF have largest production quantities The tracks between quartz and RTC represent also some parasitic capacitances and must be kept short The PCF2123 has a tuning facility where above tolerances can be compensated Tuning procedure e Measure the 32xxx Hz f signal at the CLKOUT pin e The offset is calculated as described in Fig 5 e Consult the offset table in the data sheet Take the correction value and write it into the register ODh e The correction is done by means of inhibition or addition the oscillator runs at constant speed then every 2 hours mode 0 1 second is corrected by making it shorter or longer This is only visible with CLKOUT set to 1 Hz Corrections can also be applied every minute by using mode 1 This mode will consume slightly more power lt 1 more Measure the frequency on pin CLKOUT fmeas Convert to time tmeas 1 fmeas Calculate the difference to the ideal period of 1 32768 00 Dmeas 1 32768 tmeas Calculate the ppm deviation compared to the measured value Eppm 1000000 Dmeas tmeas Calculate the offset register value Mode 0 normal mode Offset value Eppm 2 17 Mode 1 course mode Offset value Eppm 4 34 013aaa684 Fig 5 Offset calibration calculation workflow The 32 kHz quartzes are of the tuning fork type and feature a parabolic frequency response over temperature When the appl
4. quartz crystal a coin cell 1 5 V battery and the decoupling capacitor to buffer the supply voltage All signals are accessible on a row of pins overcoming the need to build a test pc board before the circuit can be evaluated or the functionality being tested together with the final application RXS 0M13512 e PCF2I23TS 9 DEMOBOARD ypp Rea 6 0 0 o C2 E e e o o o o Citmo 19 o e e o o 0 o e o o 6 ee OOOO GND VBA 1 5V Fig 1 OM13512 demo board 2 2 Real time clock PCF2123 e The PCF2123 features ultra low power consumption e Provides time and calendar from seconds to years e Accuracy is based on a 32 768 kHz quartz crystal e Low backup current while running typical 100 nA at Vpop 2 0 V and Tamb 25 C UM10759 All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 3 of 14 NXP Semiconductors U M1 0759 Demo board OM13512 for the SPl bus RTC PCF2123 e Watchdog functionality e Freely programmable timer and alarm with interrupt capability e Pre programmed 1 second or 1 minute interrupt e Clock operating voltage 1 1 V to 5 5 V e SPl bus with separate but combinable data input and output up to 8 MHz e Serial interface at Vpp 1 8 V to 5 5 V e Integrated oscillator load capacitors for quartzes with C 7 pF e Internal Power On Reset POR
5. UM10759 Demo board OM13512 for the SPl bus RTC PCF2123 Rev 1 02 June 2014 User manual Document information Info Content Keywords PCF2123 OM13512 ultra low power evaluation demo board how to get started SPI bus RTC Real Time Clock tuning battery switch watch dog timer Abstract User manual for the RTC SPl bus demo board OM13512 which contains the RTC PCF2123 NXP Semiconductors U M1 0759 Demo board OM13512 for the SPl bus RTC PCF2123 Revision history Rev Date Description v 1 20140602 First revision Contact information For more information please visit http www nxp com For sales office addresses please send an email to salesaddresses nxp com UM10759 All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 2 of 14 NXP Semiconductors U M1 0759 Demo board OM13512 for the SPl bus RTC PCF2123 1 Introduction The PCF2123 is a real time clock based on an ultra low power oscillator and using an SPl bus for interfacing The OM13512 is the ideal evaluation demo board to use during the design phase of any project just the power supply and the SPl bus must be connected In case that an I2C bus would be the preferred interface the PCF8523 with demo board OM13511 could be used for evaluation 2 Key features 2 1 Demo board OM13512 The RTC PCF2123TS with SPl bus is mounted together with a
6. agram in Fig 3 and the layout drawing in Fig 4 o NO onissi2 w PCF2123TS DEMOBOARD VDD GN Fig 4 Demo board and top side layout 5 Optional features for test and evaluation 5 1 5 2 6 Software Oscillator The characteristics of the oscillator with different quartzes can easily be verified The Resistor R4 0 Q can be replaced to simulate varying Rs of quartzes The maximum total impedance can be 100 kQ Experimental area On the board there is space for adding a custom circuitry for general purpose Vss and Vpp are available for easy set up UM10759 6 1 The actual time must be set after power on For this straight forward SPl bus instructions are used Functionality The RTC PCF2123 is controlled via a standard SPl bus interface The common SPI protocol applies The Chip Enable CE signal allows using different devices on the same bus All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 7 of 14 NXP Semiconductors U M1 0759 UM10759 6 2 Demo board OM13512 for the SPl bus RTC PCF2123 It is advised to program the control register first to set the correct functions and modes Software instructions for setting the clock 6 2 1 Setting the time 6 2 2 6 3 Setting the clo
7. ck to 3 45 PM Monday December 15 2014 e Chip select CE 1 e Software reset 10h 58h e Chip select off CE 0 e Chip select CE 1 e Address pointer 01h e Status word 0 04h 12 hour mode is selected e Status word 1 00h timer not initiated e Seconds register 00h 0 seconds clock integrity ok MSB OS 0 e Minutes register 45h 45 min e Hours register 23h PM flag 3 PM e Days register 15h 15 day of the month e Weekdays register 01h Monday ae day of the week e Months register 12h December e Years register 14h 20 14 e Chip select off CE 0 Reading the clock Example reading the clock some 2 minutes after writing e Chip select CE 1 e Set address 02h Read e Seconds e g 56 seconds clock integrity ok OS 0 e Minutes e g 46 minutes e Hours 23 3 PM e Days 15 15th e Weekdays 01 Monday e Months 12 December e Years 14 2014 e Chip select off CE 0 Frequency tuning The 32 kHz quartzes are typically sold with a tolerance at room temperature of either 10 ppm or 20 ppm Remark 11 5 ppm corresponds to 1 s day The quartzes feature a characteristic load capacity of either 7 pF or 12 5 pF Oscillators utilizing 7 pF quartzes feature slightly All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 8 of 14 NXP Semiconductors U M1 0759 Demo board OM13512 for the SPl bus RTC PCF2123
8. clock out enable pin is available to control the CLKOUT signal also by hardware 3 2 Battery back up To guarantee the autonomy of the clock a continuous power supply is needed The battery back up of the demo board assures it see Fig 3 3 3 Optimizing power consumption There are a number of factors influencing the power consumption e Supply voltage the lower the supply voltage the lower the power consumption e Oscillator the quartz crystal is specified with a series resistance Rs and a load capacitance C The PCF2123 is tailored to use quartzes with a C of 7 pF as used on the demo board If a quartz with 12 5 pF is used the frequency can be compensated either by the tuning register or by adding a 2 7 pF capacitor on the OSCI and on the OSCO C2 and C3 on the board With lower capacitance the power consumption is lower 6 pF quartzes can also be used the frequency must then slightly be adjusted via the offset register The serial resistance of the quartz dissipates energy The lower Rg the less energy is used General rule the larger the mechanical size of the quartz package the lower is the impedance Check the components parameters of your preferred quartz supplier UM10759 All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 5 of 14 NXP Semiconductors UM10759 Demo board OM13512 for the SPl bus RTC PCF2123 4 Cir
9. cuit diagram 820E cG GND VBAT BAS316 BTI Fig 3 Circuit diagram of the demo board OM13512 UM10759 4 1 Detailed circuit diagram Connectors and features e The single in line connector P1 100 mil pitch is providing access to all pins for integrating the RTC into an application e Jumper JP1 allows to measure the current consumption for this the jumper has to be removed and replaced by a pA meter circuit CLKOUT is an open drain output switches to the battery as soon as Vpp is lower than Vegar board Jumper JP2 switches in a pull up to CLKOUT in case none is provided in the target Jumper JP3 enables the battery For delivery it is set open The Schottky diode D1 Jumper JP4 allows visualizing the interrupts by the LEDs on INT on top of the e Jumper JP5 enables the CLKOUT pin When the jumper is connected to Vpp the CLKOUT is enabled when it is connected to Vss the CLKOUT is disabled e The diode D3 avoids that the remaining circuits are supplied by the battery and therefore draining it D3 is not required if no battery backup is used All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 6 of 14 NXP Semiconductors U M1 0759 Demo board OM13512 for the SPl bus RTC PCF2123 e Position of the Jumpers and connectors are found in the circuit di
10. eeeeeeeeeeeneeeeeeaes 3 Real time clock PCF2123 0000 eeeeeeeeneeeeeees 3 Hardware setup sccccssseenssseeeeesseeeeeseeeenensseenensees 4 General requirement for the PCF2123 aaaea 4 Battery back up 0 ce ceeeeeeeeeeeeeeeeeeeeeeenaeeeeeenaes 5 Optimizing power consumption eee 5 Circuit diagram ccceeeceeeceeeeeeeeeeeseeeeeeeeneeeeneeees 6 Detailed circuit diagram 6 Optional features for test and evaluation 7 OSI AON siiret iiia ainean eiea 7 Experimental area c cccceccceeseeeeeeeeeeeenaees 7 SOMW ANG i csccecceitiscdsccccvestevetrinssceveetenesnccceervssnectives 7 FUNCtiIONAlity eee cece ee eeeneeeeeeeeeeeetaeeeeeenaes 7 Software instructions for setting the clock 8 Setting the time 0 eee eeeeeeeeeeeeeeeenteeeeeeaas 8 Reading the clock 8 Frequency tuning eeeceeeesseeeeeeeeeeeenneeeeeenaes 8 Reference ceccessceecesscteesesesceeensenesenseeeseseneenens 11 Legal information cccsssseesseeeessseeneneseeeeens 12 DefinItlONS 4355 hesiii helieeceiand wehbe adeeeebelceds 12 DiSCIAIMETS cece eeeeeeeeeeeeeeeeeeeeeeeeeeeneeeeeeaaes 12 Trademarks po cei ceteaccech scootnes sun teenbeciees sec bheebsbetbess 12 List of List of figures ssssssssennssnnnnnnnnnnennnnnenne 13 COMMGINS sie cccesiacccccacecsticesessastececnesvadescnescaccecnace 14 Please be aware that important notices concerning this document and the product s described her
11. ein have been included in the section Legal information NXP B V 2014 All rights reserved For more information please visit http www nxp com For sales office addresses please send an email to salesaddresses nxp com Date of release 02 June 2014 Document identifier UM10759
12. ers are responsible for the design and operation of their applications and products using NXP Semiconductors products and NXP Semiconductors accepts no liability for any assistance with applications or UM10759 All information provided in this document is subject to legal disclaimers customer product design It is customer s sole responsibility to determine whether the NXP Semiconductors product is suitable and fit for the customer s applications and products planned as well as for the planned application and use of customer s third party customer s Customers should provide appropriate design and operating safeguards to minimize the risks associated with their applications and products NXP Semiconductors does not accept any liability related to any default damage costs or problem which is based on any weakness or default in the customer s applications or products or the application or use by customer s third party customer s Customer is responsible for doing all necessary testing for the customer s applications and products using NXP Semiconductors products in order to avoid a default of the applications and the products or of the application or use by customer s third party customer s NXP does not accept any liability in this respect Export control This document as well as the item s described herein may be subject to export control regulations Export might require a prior authorization from competent authorities Eval
13. ication is dominantly used over a limited temperature range it is often helpful to tune the frequency to be slightly higher at the UM10759 All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 9 of 14 NXP Semiconductors U M1 0759 Demo board OM13512 for the SPl bus RTC PCF2123 turnover point The error around 25 C clock goes too fast is then compensated during the time when temperature is lower or higher For example for operation between 5 C and 45 C tune the clock 8 ppm faster than the value for 25 C would be See Fig 6 20 frequency deviation Af fo g ree ppm 20 100 140 40 30 20 10 o 10 20 30 40 50 80 70 TCC 1 Characteristic if tuned to 32 768 kHz at 25 C 2 Characteristic if tuned with the positive offset Afor Fig 6 Averaged frequency over the application temperature range of 5 C to 45 C UM10759 All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 10 of 14 UM10759 Demo board OM13512 for the SPl bus RTC PCF2123 NXP Semiconductors 7 Reference 1 AN11247 Improved timekeeping accuracy with PCF85063 PCF8523 and PCF2123 using an external temperature sensor Application Note 2 PCF2123 SPI Real time clock calendar
14. ithstanding any damages that customer might incur for any reason whatsoever NXP Semiconductors aggregate and cumulative liability towards customer for the products described herein shall be limited in accordance with the Terms and conditions of commercial sale of NXP Semiconductors Right to make changes NXP Semiconductors reserves the right to make changes to information published in this document including without limitation specifications and product descriptions at any time and without notice This document supersedes and replaces all information supplied prior to the publication hereof Suitability for use NXP Semiconductors products are not designed authorized or warranted to be suitable for use in life support life critical or safety critical systems or equipment nor in applications where failure or malfunction of an NXP Semiconductors product can reasonably be expected to result in personal injury death or severe property or environmental damage NXP Semiconductors accepts no liability for inclusion and or use of NXP Semiconductors products in such equipment or applications and therefore such inclusion and or use is at the customer s own risk Applications Applications that are described herein for any of these products are for illustrative purposes only NXP Semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification Custom
15. tually paid by customer for the product or five dollars US 5 00 The foregoing limitations exclusions and disclaimers shall apply to the maximum extent permitted by applicable law even if any remedy fails of its essential purpose 8 3 Trademarks Notice All referenced brands product names service names and trademarks are property of their respective owners NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 12 of 14 NXP Semiconductors U M1 0759 Demo board OM13512 for the SPl bus RTC PCF2123 9 List of List of figures Fig 1 OM13512 demo board seee 3 Fig 2 Block diagram PCF2123 eeen 4 Fig 3 Circuit diagram of the demo board OM13512 6 Fig 4 Demo board and top side layout eee 7 Fig 5 Offset calibration calculation workflow 9 Fig 6 Averaged frequency over the application temperature range of 5 C to 45 C 10 UM10759 All information provided in this document is subject to legal disclaimers NXP B V 2014 All rights reserved User manual Rev 1 02 June 2014 13 of 14 NXP Semiconductors UM10759 10 Contents Demo board OM13512 for the SPl bus RTC PCF2123 2 1 2 2 3 1 3 2 3 3 4 1 5 1 5 2 6 1 6 2 6 2 1 6 2 2 6 3 8 1 8 2 8 3 10 Introduction cceseeeeeeseeeeeeeseeeeeenseeeeaneneenensenenennees 3 Key features cccseceseecsseessseseseessseeseseeeeseeseseeeees 3 Demo board OM13512 ee e
16. uation products This product is provided on an as is and with all faults basis for evaluation purposes only NXP Semiconductors its affiliates and their suppliers expressly disclaim all warranties whether express implied or statutory including but not limited to the implied warranties of non infringement merchantability and fitness for a particular purpose The entire risk as to the quality or arising out of the use or performance of this product remains with customer In no event shall NXP Semiconductors its affiliates or their suppliers be liable to customer for any special indirect consequential punitive or incidental damages including without limitation damages for loss of business business interruption loss of use loss of data or information and the like arising out the use of or inability to use the product whether or not based on tort including negligence strict liability breach of contract breach of warranty or any other theory even if advised of the possibility of such damages Notwithstanding any damages that customer might incur for any reason whatsoever including without limitation all damages referenced above and all direct or general damages the entire liability of NXP Semiconductors its affiliates and their suppliers and customer s exclusive remedy for all of the foregoing shall be limited to actual damages incurred by customer based on reasonable reliance up to the greater of the amount ac
Download Pdf Manuals
Related Search