$ figure 1. dms-EB-RMS schematic diagram product overview description: the dms-EB-RMS board allows the true rms value of ac signals to be displayed on 5v-powered dms-30pc/lcd digital voltmeters. the meter/board combination has an input range of 0-750vac with 2v meters (1vac resolution) or 0-199.9vac with 200mv meters (0.1vac resolution). a built-in screw-terminal block reliably interfaces signal and power connections. the dms-EB-RMS now accommodates user-installed modi?cations such as input-scaling resistors and isolated +5v dc/dc converters. power and safety precautions: the dms-EB-RMSs ac hi and ac low inputs are not electri- cally isolated from its 5v supply (ac low is connected directly to 5v return). when measuring any input signal which is derived from ac power mains, a dedicated (i.e., it only powers the dms-EB-RMS), transformer-isolated +5v supply, with a minimum 1kv breakdown rating, must be used to power the dms-EB-RMS board/meter combination. when measuring ac power mains inputs, never connect the dms-EB-RMSs 5v return to chassis/earth ground anywhere in the system. failing to follow these instructions could defeat any safety grounding and will place the system +5v power supply, and all its associated circuitry, at dangerously elevated ac-line potentials. in many applications, the ms-EB-RMS installation is required to meet electrical code requirements. to ensure safe operation, the dms-eb- rms board should only be installed and serviced by technically quali?ed personnel. see dms application note 11 for more details. features displays true rms values of ac inputs 0.5% accuracy for dms-30pc-0 or dms- 30lcd-0-5 2% accuracy for dms-30pc-1 or dms- 30lcd-1-5 also works with dms-40pc/lcd meters (see ap note 11) (C) input lo (+) input hi ref. out ref. in 1 56 3 +5v 5v return tb1 cav out +v s com Cv s cf v in cc v out lv osc v+ capC gnd cap+ boost sg1 sg2 sg3 5v return dp3 dp2 dp1 +5v supply c5 2.2f + + r1 988k r2 988k r3 1.98k + c2 10f c1 100f + 1 2 3 4 5 6 7 8 5 6 7 8 1 2 3 4 u1 u2 ac hi 3 4 5 6 1 2 sg4 j1 12 11 8 7 10 9 jp1 j6 gnd 2 1 3 u3 ps1 1 2 3 4 c4 2.2f j4 j5 ac low note: components are user-supplied and not part of the standard product. dc/dc Cv +v +v in Cv out v in v out dms-EB-RMS ac-to-rms converter application board for dms-30pc/lcd meters for full details go to www.murata-ps.com/rohs www.murata-ps.com technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000 mpm_dms-EB-RMS.b01 page 1 of 2
functional speci?cations (t a = +25c, v cc = +5v) ordering information dms-EB-RMS-c ac-to-rms conversion board dms-bzl1-c bezel assembly dms-bzl2-c bezel assembly with sealing gasket figure 2. dms-EB-RMS board vac measurement range: 200mv meters 0 to 199.9vac 2v meters 0 to 750vac conversion accuracy: 0-200vac 0.5% 0-750vac 2% crest factors 3, maximum input frequency range 40hz to 2khz primary operating power +5v (5%) current consumption (board only) +0.5ma typ., +1ma max. operating temperature range 0 to +60c storage temperature range C20 to +75c humidity 0 to 95%, non-condensing dimensions 2.02" (51.31mm)w x 0.83" (21.08mm)h dms-EB-RMS ac-to-rms converter application board for dms-30pc/lcd meters murata power solutions, inc. makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. the descriptions contained her ein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. speci?cations are subject to chan ge without notice. ? 2008 murata power solutions, inc. usa: mans?eld (ma), tel: (508) 339-3000, email: sales@murata-ps.com canada: toronto, tel: (866) 740-1232, email: toronto@murata-ps.com uk: milton keynes, tel: +44 (0)1908 615232, email: mk@murata-ps.com france: montigny le bretonneux, tel: +33 (0)1 34 60 01 01, email: france@murata-ps.com germany: mnchen, tel: +49 (0)89-544334-0, email: munich@murata-ps.com japan: tokyo, tel: 3-3779-1031, email: sales_tokyo@murata-ps.com osaka, tel: 6-6354-2025, email: sales_osaka@murata-ps.com china: shanghai, tel: +86 215 027 3678, email: shanghai@murata-ps.com guangzhou, tel: +86 208 221 8066, email: guangzhou@murata-ps.com singapore: parkway centre, tel: +65 6348 9096, email: singapore@murata-ps.com murata power solutions, inc. 11 cabot boulevard, mans?eld, ma 02048-1151 u.s.a. tel: (508) 339-3000 (800) 233-2765 fax: (508) 339-6356 www.murata-ps.com email: sales@murata-ps.com iso 9001 and 14001 registered technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000 www.murata-ps.com 12/15/08 mpm_dms-EB-RMS.b01 page 2 of 2
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