PTM 230 BATTERY POWERED – Power Supply
Contents
1. APPLICATION NOTE 205 Green Smart Wireless enocean 1 INTENTION OF THIS APPLI CATION NOTE This Application Note relates to an EnOcean PTM 230 module as a battery powered elec tronic radio switch When using a small Li MnO2 coin cell like CR2032 the transmitter module has a service life of over 5 years with in excess of 2 Million radio transmissions 2 PROBLEM According to the User Manual the PTM 230 needs a short energy pulse of around 3 to 8 ms supplied by the ECO 100 energy generator approx 250uWs to transmit an RF tele gram While the PTM 230 is supplied with energy it continuously sends telegrams When battery powered the PTM 230 thus additionally requires an external one shot generator which generates exactly one single energy pulse with each push of the button enough for one telegram 3 SOLUTI ON In the simplest case this one shot generator can be a very inexpensive CMOS component e g CD4538 monostable quiescent current of only few nA compared with about 250 nA battery self discharge current see below If an additional key control SW1 SW2 is needed both can be implemented using a small inexpensive ultra low power u controller e g MSP430F2001 4 CIRCUIT EXAMPLE FOR PUSHBUTTON PRESSED TRANSMITS A TELEGRAM This circuit example shows a single micro pushbutton application Each time the button is pushed the circuit transmits an ON SW1 at Vcc telegram A typical application is e g2. automatic stairwell lighting light is switched on manually and switches off automatically after a specified time 4 1 Key components E RF transmitter module EnOcean PTM 230 E Signal generator CD4538 E wu pushbutton EVQPO gt 2 mill switching operations Battery CR2032 from Renata 3 V 235 mAh 30 70 C Li MnO2 self discharging rate at 23 C lt 1 year 4 2 Energy pulse duration The duration T of the energy pulse must be long enough to allow the transmission of en ergy for a complete telegram containing 3 sub telegrams On the other hand T should not be unnecessarily long since excess energy is converted into heat and thus wasted see User Manual PTM 230 For these reasons the duration T was chosen to be about 10ms According to Data Sheet CD4538 this results in the following APPLICATION NOTE 205 Green Smart Wireless enocean T RC 10 ms L0OMQ x 1 nF C should be kept as small as possible to avoid wasting energy due to charging and dis charging of the capacitor The 1 nF capacitor calculated above assures the transmitting of a complete standard telegram consisting of at least 3 sub telegrams With increasing or decreasing his value the number of the transmitted sub telegrams may be varied If for example 2 sub telegrams are enough 470 680 pF would be also sufficient During one transmission peak currents as high as about 15 mA for few milliseconds only will be drawn from the power su
3. pen SW1 open The PTM 230 transmits an EnOcean radio telegram which is provided at the serial output of a SW2 open SW2 open SW2 Vcc SW2 Vcc SW2 Vcc SW2 Vcc SW2 open SW2 open PWR1 Data 00010000Status XX11RRRR PWR1 Data 00000000Status XX11RRRR PWR1 Data 00110000Status XX11RRRR PWR1 Data 00100000Status XX11RRRR PWR1 Data 00110001Status XX11RRRR PWR1 Data 00100001Status XX11RRRR PWR1 Data 0001xxxx Status XX1ORRRR PWR1 Data 0000xxxx Status XX10RRRR RCM 120 or TCM 120 module with the following parameters Unique factory programmed 32bit ID a Data2 Datal Data0 0 a Data3 and Status as follows SW1 SW ORG Data3 Status open open 0x05 000PXXXX XX10RRRR Wiec open 000P0000 XX11RRRR e e aKOSe 001P0000 XX11RRRR Vec V 0x05 001P0001 XX11RRRR P polarity X reserved R repeater counter The polarity P is defined as follows PWR1 PWR2 Fig 3 PTM 230 input codings from User Manual Disclaimer The information provided in this document describes typical features of the EnOcean radio system and should not be misunderstood as specified operating characteristics No liability is assumed for errors and or omissions We reserve the right to make changes without prior notice For the latest documentation visit the EnOcean website at www enocean com
4. pply Since a small coin battery alone has a limited ampacity it could be helpful to use a low leakage buffer SMD Tantalum or ceramic capacitor of about 47 100 uF in parallel to avoid a long time damage of the battery VDD FON3 42 AA CR2B32F Uce PTH230 GND CHS38BCH GND Fig 1 Circuit Example A 4 3 Energy Balance In classic applications a PTM 230 needs a relatively short energy pulse of approx lt 250 uWs to transmit a telegram Using a typical 2 5 3 V supply voltage this roughly corre sponds to a battery draw of 100 pAs Since the nominal battery capacity is generally pro vided in Ah 100uAs equals 100 x 10 6 x 1 3600 Ah 0 000000028 Anh per telegram Even a battery capacity of a mere 0 150 Ah a coin cell CR2032 has gt 0 220 Ah would theoretically mean 1500 x 3600 5 4 Million telegrams Bearing in mind that the energy of a battery cannot be fully drawn for this only approx 50 a single CR2032 coin cell still allows more than 2 Millions telegrams to be transmitted e APPLICATION NOTE 205 Green Smart Wireless enocean 5 CIRCUIT EXAMPLE FOR PUSHBUTTON PRESSED RELEASED TRANSMITS A TELEGRAM For a separate transmission of the status button pushed or button released the polarity of the PTM 230 input voltage must in each case be reversed PWR1 and PWR2 Via the two coding inputs SW1 and SW2 of the PTM 230 it is possible to program up to four buttons in
5. the data telegram The required signal combinations can be created using a small micro controller with some SW programming All SW states plus polarity combinations are listed in the PTM 230 User Manual Important is that the receiver is able to interpret the different SW and PWR combinations Gi CR2832FH IC4 MSP43 F 2804Pl1 P2 6 XIN P1 8 TACLK ACLK CAG P2 7 XDUT mi p a L T TEST SBHTCK RST NMI SBHTDIO A 1 F 2 F P14 3 CAOUT CAS P4 7 CAOUT CA7 TDO TDI S3 P1 4 SMCLK CA4 TCK P1 6 TA1 CAS TDI TELK are ole P1 5 TAC CAS THS GND or GND GND GND vi StE me GND DTM23GH 91 2 FDC6386P Fig 2 Circuit Example B 5 1 Dimensioning It is important for the dimensioning that the individual control signals have the required length are synchronized SW with appropriate PWR and that the PWR polarity pulses do not overlap at any time include delay time Only then cross currents during polarity re versal by the MOSFETS can be prevented The SW states must already exist before the en ergy pulse comes The micro controller MSP430F2001 was chosen due to its favorable price and low power consumption 100 nA APPLICATION NOTE 205 Green Smart Wireless enocean 5 2 Examples of SW and PWR combinations Action S1 closed SW1 Vcc Action S1 open SW1 Vcc Action S2 closed SW1 open Action S2 open SW1 open Action S3 closed SW1 Vcc Action S3 open SW1 Vcc Action S4 closed SW1i open Action S4 o
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