introduction the sa2002d pin programmable monochip meter this application note describes the functionality of the sa2002d metering integrated circuit using the PM2002dp evaluation module. the sa2002 enables the meter manufacturer to build a meter that measures the energy consumption, and records it to a mechanical counter. energy flow direction as well as energy metering activity is indicated by means of leds. this application note will focus on the practical use of the sa2002d, more detailed information specific to the sa2002d can be found in the applicable datasheet. s a m e s s a m e s application note: energy meter evaluation module PM2002dp 1/10 spec-0088 (rev. 1) 08-11-00 setting 6a / 220v 10a / 220v20a / 220v 30a / 220v 40a / 220v 60a / 220v 80a / 220v pin status r0 = 0, r1 = 0, r2 = 1 r0 = 0, r1 = 0, r2 = 0r0 = 1, r1 = 0, r2 = 0 r0 = 1, r1 = 0, r2 = 1 r0 = 0, r1 = 1, r2 = 0 r0 = 0, r1 = 1, r2 = 1 r0 = 1, r1 = 1, r2 = 0 calibrated led imp/kwh 64006400 3200 3200 1600 1600 800 connectors on module the PM2002dp module connects directly to live and neutral on sck1. the module is referenced to live and should be kept in mind when connecting test equipment to the module. the current is measured by the shunt on the top of the pcb. the left terminal of the shunt is connected to live. the live out will be connected to the right terminal of the shunt. table 1: a summary of the pin settings possible with the sa2002d. pin status 0 indicates connection to vss and 1 indicates connection to vdd. name sck1 jp2jp3 function description mains connector for module power and voltage sense optional current transformer connector. (underneath shunt resistor) optional stepper motor connector. (remove jumper j6 to disconnect impulse counter) table 2: connector descriptions live in neutral live out figure 1: connection and jumper settings for 80a / 220v bi-directional meter module
s a m e s s a m e s PM2002dp 2/10 http://www.sames.co.za module setup the PM2002dp module is setup for use with the sa2002d integrated circuit. resistor values used on the module are calculated for rated conditions of 80a/220v. iin iip vref r2 r1 r0 fast vdd cnf nc agnd ivp diri diro nc mon vss led mop nc p4 p5 p6 p7 p8 p9 p10 j3 p17 p16 p15 p14 p13 p12 p11 p18 j4 vdd vss j15 vdd vss j14 vdd vss j13 vdd vss j12 vdd vss j11 vdd vss j1 j2 1 2 jp3 vss j6 6 5 4 3 2 1 . 1 sa2002d figure 2: jumper schematic, digital io?s name function description j1 j1 is used to select the energy direction ( diri pin). the three options available are: p18 connected to vdd - negative energy measurementp18 connected to vss - positive energy measurement p18 connected to j2 (p17) - bi-directional energy measurement p18 should not be left floating and must be connected to one of the options described above. j2 j2 is only used to select bi-directional energy measurement when connected to p18 j3 and j4 these are test points placed next to the digital pins of the sa2002e j5 not fitted this is the current sense input ground. if a current transformer is used for current sensing the two pins of j5 must be connected. j6 connects the impulse to vss. if a stepper motor is connected to jp3 then j6 should be left open. j7 analog ground test point (see figure 1) j8 positive supply test point (vdd) (see figure 1) j9 negative supply test point (vss) (see figure 1) j11, j12 and j13 used to select the r2, r1 and r0 pins of the sa2002d for the various rated conditions. refer to table 1 for the possible settings j14 used to select fast calibration mode. connecting p7 to vdd selects fast calibration mode. for normal operation p7 must be connected to vss j15 used to select between normal and configure / test modes. for normal operation connect p9 to vss. j16 used to select between 220v and 110v mains systems (see figure 3). leave open for 220v mains. table 3: jumper settings for various device options
s a m e s s a m e s PM2002dp 3/10 http://www.sames.co.za analog section the analog (metering) interface described in this section is designed for measuring 220v/80a with precision better than class 1. the most important external components for the sa2002d integrated circuit are the current sense resistors, the voltage sense resistors and the bias setting resistor. the resistors used in the metering section should be of the same type so temperature effects are minimized. voltage input ivp the voltage input of the sa2002d (ivp) is driven with a current of 14a at nominal mains voltage. this voltage input saturates at approximately 17a. at a nominal voltage current of 14a allows for 20% overdriving. the mains voltage is divided with a voltage divider to 14v that is fed to the voltage input pins via a 1m w resistor voltage divider the voltage divider is (figure 3) calculated for a voltage drop of 14v. t reat c7 as a short circuit and ignore j16. equations for the voltage divider in figure 3 are: rb = r1 + r2 + r3 + r15 + r10 rb = r12 || ( r11 + p1 / 2) combining the two equations gives: (ra + rb) / 220v = rb / 14v values for resistors r10 = 47 w , r11 = 22k w , p1=10k w and r12 = 1m w is chosen. substituting the values result in: rb = 26.29k w ra = rb x (220v / 14v - 1)ra = 386.84k w figu re 3: mai ns vo ltage divid er r1 r2 r3 r10 r11 r12 neutral c7 r15 j16 p1 live in standard resistor values of r1, r2, r3 and r15 are chosen to be 47k w , 150k w , 47k w and 150k w . the resistor ra is divided so that the voltage drop across one resistor is within the specified limits of the resistor type that is used, usually 200vdc. the resistor value ratios are chosen so that shorting j16 the module could be used on a 110v ac mains system. current sensor input resistors figure 4 (using a shunt resistor)the resistors r6, r7 define the current level into the current sense inputs the device. the voltage drop across the shunt should be at least 20mv at rated conditions. a shunt resistor with a value of 50mv @80a was chosen for the application module for its ease of use. the resistor values are calculated for an input current of 16a on the current inputs at rated conditions. for a 80a meter the resistor values are calculated as follows: r6 = r7 = (i / 16a) x r / 2 l sh = 80a / 16a x 625u w / 2 = 1.5625k w i line current l = a standard value of 1.6k w is chosen. figu re 4: cur rent inpu t con figur ation r6 r7 r14 live in live out l
s a m e s s a m e s PM2002dp 4/10 http://www.sames.co.za ct termination resistor provision is made for the use of a current transformer on the module. the existing shunt needs to be removed and the current sense resistors will have to be recalculated for the specific current transformer. the voltage drop across the ct termination resistor at rated current should be at least 20mv. the ct's used should have a low phase shift and a ratio of 1:2500.the ct is terminated with a 2.7 w resistor giving a voltage drop of 864mv across the termination resistor at rated conditions current sensor input resistors figure 5 (using a current transformer)the resistors r6, r7 define the current level into the current sense inputs the device. the resistor values are selected for an input current of 16a on the current inputs at rated conditions. for an 80a-rated meter the resistor values are calculated as follows: r6 = r7 = (i / 16a) x r / 2 l sh = 80a / 16a x 2.7 w / 2 = 2.7k w i line current l = rsh = ct t ermination resistor 2500 = ct ratio figure 5: current input configuration live in live out r16 iin iip j5 l ct1 r6 r7 phase compensation (when using a current transformer) phase shift caused by the current transformer may be corrected by inserting a capacitor in the voltage divider circuit. see figure 6, capacitor c7. to compensate for a phase shift of 0.18 degrees the capacitor value is calculated as follows: c = 1 / (2 x p x mains frequency x r5 x tan (phase shift angle)) c = 1 / (2 x p x 50 x 1m x tan( 0.18 degrees)) c = 1.013f reference voltage vref the vref pin of the sa2002d is connected to a resistor that determines the on chip bias current. ground gnd the gnd pin of the sa2002d is to the live phase, which is halfway between vdd and vss. note that supply bypass capacitors c1 and c2 are positioned as close as possible to the supply pins of the device, and connected to a solid ground plane.
s a m e s s a m e s PM2002dp 5/10 symbol description detail sa2002d diode, silicon, 1n4007 resistor, 47k, 1/4w , 1%, metal resistor, 150k, 1/4w , 1%, metal resistor, 100r, 1/4w , 1%, metal resistor, 1.6k, 1/4w , 1%, metal resistor, 2.4k, 1/4w , 1%, metal resistor, 47r, 2w , 5%, wire wound resistor, 22k, 1/4w , 1%, metal resistor, 1m, 1/4w , 1%, metal resistor, 24k, 1/4w , 1%, metal shunt resistor, 80a / 50mv resistor, 1/4w , 1%, metal capacitor, 220nf capacitor, 220nf , 16v, electrolytic capacitor, 470nf , 250vac capacitor, 820nf capacitor capacitor, 2200uf , 16v, electrolytic 3mm light emitting diode impulse counter, kuebler , k07.80 molex 3 pin connector, 200mil pin spacing molex 2 pin connector, 100mil pin spacing jumpers header pins u1 d1, d2 r1, r3 dip-20 r2, r15 r4, r5 r6, r7 r8, r9 r10 r11 r12 r13 r14 r16 p1 c1, c2 c3, c4 c5 c6 c7 c8 led1, led2 cnt1 sck1 jp3 6 24 http://www.sames.co.za component lists the following component list covers all components fitted on the PM2002dp module as shipped diode, zener, 2.4v d3, d4 resistor, 1/4w , 1%, metal note 1 note 1 note 2 note1: in case a current transformer is used on the board r16 is the termination resistor. resistors r6 and r7 values may need to be changed to match the ct used. note2: capacitor values may be selected to compensate for phase errors caused by current transformers. table 4: components for pm200dp module set up for 220v/80a
s a m e s s a m e s PM2002dp 6/10 http://www.sames.co.za figure 6: schematic diagram of the complete PM2002dp module c1 d1 + c3 c2 r1 r2 r3 d2 + c4 r4 r5 d3 d4 c5 r10 r11 r12 r6 r7 r13 c6 live in neutral live out neutral b a sb sa r14 r2 4 r1 5 fast 7 r0 6 vdd 8 cnf 9 10 vref 3 iip 2 iin 1 gnd 20 ivp 19 diri 18 diro 17 16 mon 15 vss 14 led 13 mop 12 11 u1 .1 1 2 3 4 5 6 cnt1 r8 r9 1 2 sck1 j11 j12 j13 j14 vss vss vss vss vdd vdd vdd vdd j1 j2 vdd vss p4 p5 p6 p7 p10 p11 p12 p13 p15 p16 p17 p18 iin iip n l lo j7 j8 j9 led1 led2 j15 vdd p9 mm c7 r15 j16 p1 1 2 jp3 j6 + c8 nc nc nc
s a m e s s a m e s PM2002dp 7/10 figure 7: top layer layout of the PM2002d module http://www.sames.co.za pcb la yout figure 8: bottom layer layout of the PM2002d module
s a m e s s a m e s PM2002dp 8/10 http://www.sames.co.za figure 9: silkscreen of the PM2002d module
s a m e s s a m e s pm9607ap s a m e s s a m e s PM2002dp 9/10 http://www.sames.co.za note:
10/10 http://www.sames.co.za s a m e s s a m e s pm9607ap s a m e s s a m e s PM2002dp disclaimer: the information contained in this document is confidential and proprietary to south african micro-electronic systems (pty) ltd ("sames") and may not be copied or disclosed to a third party, in whole or in part, without the express written consent of sames. the information contained herein is current as of the date of publication; however, delivery of this document shall not under any circumstances create any implication that the information contained herein is correct as of any time subsequent to such date. sames does not undertake to inform any recipient of this document of any changes in the information contained herein, and sames expressly reserves the right to make changes in such information, without notification, even if such changes would render information contained herein inaccurate or incomplete. sames makes no representation or warranty that any circuit designed by reference to the information contained herein, will function without errors and as intended by the designer. any sales or technical questions may be posted to our e-mail address below: energy@sames.co.za for the latest updates on datasheets, please visit our web site: http://www.sames.co.za. south african micro-electronic systems division of labat technologies (pty) l td tel: (012) 333-6021 tel: int +27 12 333-6021 fax: (012) 333-8071 fax: int +27 12 333-807 1 p o box 15888 33 eland street lynn east 0039 republic of south africa 33 eland street koedoespoort industrial area pretoria republic of south africa
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