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78m6613 single - phase ac power measu rement ic data sheet ds_6613_018 19 - 5348 ; rev 2; 1 /12 description the teridian ? 78 m 6613 is a highly integrated ic for simplified implementation of single - phase ac power measurement into power supplies, smart appliances, and other applications with embedded ac load monitoring and control. it is packaged in a small , 5 mm x 5mm , 32 - pin qfn package for optimal space savings . at the measurement interface, t he device provides four analog inputs for interfacing to voltage and current sensors. v oltage s from the sensors are fed to our single converter technology ? that uses a 2 2-b it delta - sigma adc, independent 32 - bit compute engine (ce), digital temperature compensation, and precision voltage references to provide better than 0.5% power measurement accuracy over a wide 2000:1 dynamic range . the integrated mpu core and 32 kb of f lash memory provides a flexible means of configuration, post - processing, data formatting, and interfacing to any host processor through the uart interface and/or dio pins. complete application firmware is available and can be preloaded into the ic during manufacturing test . a lternatively, a complete array of ice, development tools , and programming libraries are available to allow customization for each application . 80515 mpu timers a0 a1 xin xout vref tx rx v3p3 gnd dio 4-8 dio 14-17, 19 ice serial port osc/pll converter dio, pulse 32-bit compute engine 32kb flash 2kb ram voltage ref regulator earth ground isolated supply teridian 78m6613 32 khz live neut ice_e gnd v3p3 temp sensor a2 a3 features ? < 0.5% wh accuracy o ver w ide 2000:1 current range a nd over temperature ? voltage r eference < 40ppm/c ? four sensor inputs v 3p3 a r eferenced ? 22- bit delta - sigma adc with independent 32 - bit compute engine (ce) ? 8-b it mpu (80515), one clock cycle per i nstruction with 2kb mpu xram ? 32 kb flash with security ? i ntegrated in - circuit emulator ( ice ) in terface for mpu d ebug ? 32khz time base with hardware watchdog timer ? uart interfac e and u p to 10 general - purpose 5 v tolerant i/ o pins ? packaged in a rohs -c ompliant (6/6) l ead (pb)-f ree , 32 -p in qfn (5 mm x 5mm) ? complete applicati on firmware p rovides: o true rms c alculations for current, voltage, line frequency, real power, reactive power, apparent power , and power factor o accumulated watt - hours, kilowatt - hours o intelligent switch control at zero c rossings o digital temperature compensa tion o phase c ompensation ( 15 ) o quick calibration routines o 46 C 64hz line frequency range with same c alibration terid ian is a trademark and single converter technology is a registered trademark of maxim integrated products, inc. downloaded from: http:/// available for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim?s website at www.maxim lqwhjudwhg .com.
78m6613 data sheet ds_6613_018 tab le of contents 1 hardware description .................................................................................................................... 5 1.1 hardware overview ................................................................................................................ 5 1.2 analog front end (afe) .......................................................................................................... 6 1.2.1 input multiplexer .......................................................................................................... 6 1.2.2 a/d converter (adc) .................................................................................................. 6 1.2.3 fir filter ..................................................................................................................... 6 1.2.4 voltage references ..................................................................................................... 6 1.2.5 temperature sensor ................................................................................................... 7 1.2.6 functional description ................................................................................................ . 7 1.3 digital computation engine (ce) ............................................................................................ 8 1.4 80515 mpu core .................................................................................................................... 8 1.4.1 uart .......................................................................................................................... 8 1.4.2 timers and c ounters ................................................................................................... 9 1.5 on - chip resources ................................................................................................................. 9 1.5.1 oscillator ..................................................................................................................... 9 1.5.2 pll and internal clocks .............................................................................................. 9 1.5.3 temperature sensor ................................................................................................... 9 1.5.4 flash memory ............................................................................................................. 9 1.5.5 digital i/o .................................................................................................................. 10 1.5.6 hardware watchdog timer ........................................................................................ 10 1.5.7 program security ...................................................................................................... 10 1.5.8 test ports .................................................................................................................. 10 2 functional description ................................................................................................................ 11 2.1 theory of operation .............................................................................................................. 11 2.2 reset behavior ..................................................................................................................... 12 2.3 data flow ............................................................................................................................. 12 2.4 ce/mpu communication ...................................................................................................... 13 3 application information .............................................................................................................. 14 3.1 connection of sensors (ct, resistive shunt) ........................................................................ 14 3.2 temperatu re measurement ................................................................................................... 15 3.3 temperature compensation .................................................................................................. 15 3.4 connecting 5v devices ......................................................................................................... 16 3.5 uart (tx/rx) ...................................................................................................................... 16 3.6 reset function and reset pin connections ........................................................................... 16 3.7 connecting the emulator port pins ....................................................................................... 18 3.8 crystal oscillator ................................................................................................................... 19 3.9 flash programming .............................................................................................................. 19 3.10 mpu firmware library .......................................................................................................... 19 3.11 measurement calibration ...................................................................................................... 19 4 electrical specifications ............................................................................................................. 20 4.1 absolute maximum ratings .................................................................................................. 20 4.2 recommended external components ................................................................................... 21 4.3 recommended operating conditions .................................................................................... 21 4.4 performance specifications .................................................................................................. 21 4.4.1 input logic levels ..................................................................................................... 21 4.4.2 ou tput logic levels .................................................................................................. 21 4.4.3 supply current .......................................................................................................... 22 4.4.4 crystal oscillator ....................................................................................................... 22 4.4.5 vref ........................................................................................................................ 22 4.4.6 adc converter, v3p3 referenced ............................................................................ 23 4.4.7 temperature sensor ................................................................................................ . 23 downloaded from: http:///
ds_6613_018 78m6613 data sheet 4.5 timing specifications ............................................................................................................ 24 4.5.1 ram and flash memory ............................................................................................ 24 4.5.2 reset ...................................................................................................................... 24 4.5.3 typical performance data ......................................................................................... 25 5 packaging .................................................................................................................................... 26 5.1 pinout ................................................................................................................................... 26 5.2 package outline (qfn 32) .................................................................................................... 27 5.3 recommended pcb land pattern for the qfn - 32 package ................................................. 28 6 pin descriptions .......................................................................................................................... 29 6.1 power/ground pins ............................................................................................................... 29 6.2 analog pins .......................................................................................................................... 29 6.3 digital pins ........................................................................................................................... 30 7 i/o equivalent circuits ................................................................................................................ 31 8 ordering information ................................................................................................................... 32 9 contact information .................................................................................................................... 32 revision history .................................................................................................................................. 33 fig ures figure 1: ic functional block diag ram .................................................................................................... 4 figure 2: afe block diagram .................................................................................................................. 7 figure 3: connecting an external load to dio pins ............................................................................... 10 figure 4: voltage. current, momentary and accumulated energy .......................................................... 11 figure 5: mpu/ce data flow ................................................................................................................ 12 figure 6: mpu/ce communication ........................................................................................................ 13 figure 7: resistive voltage divider ........................................................................................................ 14 figure 8: resistive current shunt .......................................................................................................... 14 figure 9: current transformer ............................................................................................................... 14 figure 10: connections for the rx pin ................................................................................................... 16 figure 11: 78m6613 external reset behavior ........................................................................................ 17 figure 12: max810s connections to the 78m6613 ................................................................................ 17 figure 13: reset g enerator based on tl431 shunt re gulator .............................................................. 18 figure 14: external components for the emulator interface .................................................................. 18 figure 15: wh accuracy, 10 ma to 20 a at 120 v/60 hz and room temperature using a 4 m ? current shunt ....................................................................................................................... 25 figure 16: typical measurement accuracy over temperature relative to 25c ..................................... 25 figure 17: 32 - pin qfn pinout ............................................................................................................... 26 figure 18: package outline (qfn 32) .................................................................................................... 27 figure 19: recommended pcb land pattern dimensions ..................................................................... 28 figure 20: i/o equivalent circuits .......................................................................................................... 31 table table 1: inputs selected in regular and alternate multiplexer cycles ...................................................... 6 downloaded from: http:///
78m6613 data sheet ds_6613_018 a0a1 mux xin xout vref ckadc cktest ce 32 bit compute engine mpu (80515) ce control reset emulator port ce_busy uart tx rx xfer busy data 00-7f prog 000-7ff data 0000-ffff prog 0000-7fff 0000-7fff mpu xram (2kb) 0000-07ff digital i/o 2000-20ff i/o ram ce ram (0.5kb) memory share 1000-11ff rtclk (32khz) mux_sync ckce ckmpu ck32 4.9152mhz < 4.9152mhz 4.9152mhz v3p3a volt reg 32khz tmuxout mpu_rstz gnda vbias cross ck_gen osc (32khz) ck32 mck pll vref div adc mux ctrl strt mux mux ckfir 4.9152mhz dio14 test test mode < 4.9152mhz dio8 sdck sdout sdin e_rxtx e_tclk e_rst flash (32kb) v3p3 fir ck_2x vbias memory share e_rxtxe_tclk e_rst (open drain) ice_e ? adc converter + - vref test mux temp a2a3 v3p3d gndd dio4dio5 dio6 dio7 dio19 dio17 dio16 dio15 figure 1 : ic functional block diagram downloaded from: http:///
ds_6613_018 78m6613 data sheet 1 hardware description 1.1 hardware overview the teridian 78m6613 single - chip measurement unit integrates all primary functional blocks required to embed solid - state ac power and ener gy measurement . included on chip are : ? an analog front end (afe) ? a n independent digital computation engine (ce) ? a n 8051 - compatible microprocessor (mpu) which executes one instruction per clock cycle (80515) ? a voltage reference ? a temperature sensor ? ram and flash memory ? a variety of i/o pins c urrent sensor technologies supported include current transformers (ct) and resistive shunts. in a typical application, the 32 - bit compute engine (ce) of the 78m 6613 sequentially processes the samples from the voltage inputs on pins a0 , a1, a2 , a3 and performs calculations to measure active energy (wh), reactive energy (varh), a 2 h, and v 2 h for four - quadrant measurement . these measurements are then accessed by the mpu, processed further and output using the peri pheral interfaces available to the mpu. in addition to the temperature - trimmed ultra - precision voltage reference, the on - chip digital temperature com pensation mechanism includes a temperature sensor and associated controls for correction of unwanted temperature effects on meas urement . temperature dependent external components such as crystal oscillator, current transformers (cts), and their corresponding signal conditioning circ uits can be character ized and their correction factors can be programmed to prod uce measurements with exceptional accuracy over the industrial temperature range, if desired. a block diagram of the ic is shown in figure 1 . a detailed description of various functional blocks follows. downloaded from: http:///
78m6613 data sheet ds_6613_018 1.2 analog front end (afe) the afe of the 78m 6613 is comprised of an input multiplexer, a delta - sigma a/d converter and a voltage reference. 1.2.1 input multiplexer the input multiplexer supports up to four input signals that are applied to pins a0 , a1, a2 and a3 of the device . additionally, using the alternate mux selection, it has the ability to select the on - chip temperature sensor . the multiplexer can be operated in two modes: ? during a normal multiplexer cycle, the signals from the a0 , a2 , a1, and a3 pins are selected. ? during the alternate multiplexer cycle, the temperature signal (temp) is selected, along with the signal sources shown in table 1 . the alternate mux cycles are usually performed infrequently (e.g. every second) by the mpu . table 1 details the regular and alternative mux sequences . missing samples due to an alt multiplexer sequence are filled in by the ce. table 1 : inputs selected in regular and alternate multiplexer cycles regular mux sequence alt mux sequence mux state mux state 0 1 2 3 0 1 2 3 a0 a1 a2 a3 temp a1 v3p3d a3 in a typical application, a1 and a3 are connected to current sensors that sense the current on each branch of the line voltage . a0 and a2 are typically connected to voltage sensors through resistor dividers. the multiplexer control circuit is clocked by ck32, the 32 . 768 k hz clock from the pll block, and launches with each new pass of the ce prog ram. 1.2.2 a/d converter (adc) a single delta - sigma a/d converter digitizes the voltage and current inputs to the 78m 6613 . the resolution of the adc is 2 2 bits . conversion time is two cycles of the ck32 clock. initiation of each adc conversion is controlled by the multiplexer control circuit as described previously . at the end of each adc conversion, the fir filter output data is stored into the ce dram location . 1.2.3 fir filter the finite impulse response filter is an integral part of the adc and it is optimized for use with the multiplexer . the purpose of the fir filter is to decimate the adc output to the desired resolution . at the end of each adc conversion, the output data is stored into the fixed ce dram location determined by the multiplexer selection . 1.2.4 voltage references the device includes an on - chip precision bandgap voltage reference that incorporates auto - zero techniques . the reference is trimmed to minimize errors caused by component mismatch and drift . the result is a voltage output with a predictable temperature coefficient. downloaded from: http:///
ds_6613_018 78m6613 data sheet 1.2.5 temperature sensor the 78m 6613 includes an on - chip temperature sensor implemented as a bandgap reference . it is used to determine the die temperature . the mpu reads the temperature sensor output during alternate multiplexer cycles . the primary use of the temperature data is to determine the magnitude of compensation required to offset the thermal drift in the system (see section 3.3 temperature compensation ). 1.2.6 functional description the afe functions as a data acquisition system, controlled by the mpu . the input signals ( a0 , a1, a2 , and a3 ) are sampled and the adc counts obtained are stored in ce dram where they can be accessed by the ce and, if necessary, by the mpu . alternate multiplexer cycles are initiated less frequently by the mpu to gather access to the slow temperature signal . a0 a1 mux vref 4.9152 mhz vbias cross ck32 vref mux ctrl mux v3p3a fir vbias ? adc converter + - vref temp fir_done fir_start a2 a3 figure 2 : afe block diagram downloaded from: http:///
78m6613 data sheet ds_6613_018 1.3 digital computation engine (ce) the ce, a dedicated 32 - bit signal processor, performs the precision computations necessary to accurately measure energy . the ce calculations and processes include: ? multiplication of each current sample with its associated voltage sample to obtain the energy per sample (when multiplied with the constant sample time). ? frequency - insensitive delay cancellation on all channels (to compensate for the delay bet ween samples caused by the multiplexing scheme). ? 90 phase shifter (for narrowband varh calculations). ? monitoring of the input signal frequency (for frequency and phase information). ? monitoring of the input signal amplitude (for sag detection). ? scaling of the processed samples based on calibration coefficients. ce code is provided by m axim as a part of the application firmware available. the ce is not programmable by the user. measurement algorithms in the ce code can be customized by m axim upon request. the ce program resides in flash memory. common access to flash memory by ce and mpu is controlled by a memory share circuit. allocated fla sh space for the ce program cannot exceed 1024 words (2 kb ). the ce dram can be accessed by the ce and the mpu. holding registers are used to convert 8 - bit wide mpu data to/from 32 - bit wide ce dram data, and wait states are inserted as needed, dependi ng on the frequency of ckmpu. the ce dram contains 128 32 - bit words. the mpu can read and write the ce dram as the primary means of data communication between the two processors. ce hardware issues an interrupt when accumulation is complete. 1.4 80515 mpu core the 78m 6613 includes an 80515 mpu (8 - bit, 8051 - compatible) that processes most instructions in one clock cycle. using a 5 mhz (4.9152 mhz) clock results in a processing throughput of 5 mips. the 80515 architecture eliminates redundant bus states and implements parallel execution of fetch and execution phases. normally a machine cycle is aligned with a memory fetch, therefore, most of the 1- byte instructions are performed in a single cycle. this leads to an 8x performance (in average) improvem ent (in terms of mips) over the intel 8051 device running at the same clock frequency. actual processor clocking speed can be adjusted to the total processing demand of the application (measurement calculations, memory management and i/o management) . typical power and energy measurement functions based on the results provided by the internal 32 - bit compute engine (ce) are available for the mpu as part of m axim s standard library. mpu memory organization, special function registers, interrupts, counters, and other controls are described in the applicable firmware documentation . 1.4.1 uart the 78m 6613 includes a uart that can be programmed to communicate with a variety of external device s . the uart is a dedicated 2 - wire serial interface , which can communicate with an external device at up to 38,400 bits/s . all uart transfers are pro grammable for parity enable, parity, 2 stop bits/1 stop bit and xon/xoff options for variable communication baud rates from 300 to 38 , 400 bps . downloaded from: http:///
ds_6613_018 78m6613 data sheet 1.4.2 timers and counters the 80515 has two 16 - bit timer/counter registers: timer 0 and timer 1. these registers can be configured for counter or timer operations. in timer mode, the register is incremented every machine cycle, meaning that it counts up after every 12 periods of the mpu clock signal. in counter mode, the register is incremented when the falling edge is observed at the corres ponding input signal t0 or t1 (t0 and t1 are the timer gating inputs derived from certain dio pins, see the dio ports section). since it takes 2 machine cycles to recognize a 1 - to - 0 event, the maximum input count rate is 1/2 of the oscillator frequency. there are no restrictions on the duty cycle, however to ensure proper recognition of 0 or 1 state, an input should be stable for at least 1 machine cyc le. 1.5 on - chip resources 1.5.1 oscillator the 78m 6613 oscillator drives a standard 32.768 khz watch crystal . these crystals are accurate and do not require a high - current oscillator circuit . the 78m 6613 oscillator has been designed specifically to handle these crystals and is compatible with their high impedance and limited power handling capability. 1.5.2 pll and internal clocks timing for the device is derived from the 32.768 khz oscillator output . on - chip timing functions include the mpu master clock and the delta - sigma sample clock . in addition, the mpu has two general counter/timers . the adc master clock, ckadc, is generated by an on - chip pll. it multiplies the oscillator output frequency ( ck32) by 150. the ce clock frequency is always ck32 * 150, or 4.9152 m hz, where ck32 is the 32 khz clock . the mpu clock frequency is scalable from 4.9152 mhz down to 38.4 khz . the circuit can also generate a 2x mpu clock for use by the emulator . 1.5.3 temperature sensor the device includes an on - chip temperature sensor for determining the temperature of the bandgap reference. the primary use of the temperature data is to determine the magnitude of compensation required to offset the thermal drift in the system (see section 3.3 temperature compensat ion ). 1.5.4 flash memory the 78m 6613 includes 32 kb of on - chip flash memory. the flash memory primarily contains mpu and ce program code. it also contains images of the ce dram, mpu ram, and i/o ram. on power - up, before enabling the ce, the mpu copies these images to their respective locations. allocated flash space for the ce program cannot exceed 1024 words (2 kb ). mpu ram: the 78m 6613 includes 2 kb of static ram memory on - chip (xram) plus 256 b of internal ram in the mpu core. the 2k b of static ram are used for data storage during normal mpu operations. ce dram : the ce dram is the working data memory of the ce (128 32 - bit words). the mpu can read and write the ce dram as the primary means of data communication between the two processors . downloaded from: http:///
78m6613 data sheet ds_6613_018 1.5.5 digital i/o the device includes up to 10 pins of general purpose digital i/o . when configured as inputs, these pins are 5v compatible (no current - limiting resistors are needed) . on reset or power - up, all dio pins are inputs until they are configured for the desired direction under mpu control . when driving leds, relay coils etc., the dio pins should sink the current into ground (as shown i n figure 3 , right), not source it from v3p3 (as in figure 3, left ) . if more than one input is connected to the same resource, the resources are combined using a logical or. figure 3 : connecting an external load to dio pins 1.5.6 hardware watchdog timer in addition to the basic watchdog timer included in the 80515 mpu, an independent, robust, fixed - duration, watchdog timer (wdt) is included in the device . it uses the crystal oscillator as its time base and must be refreshed by the mpu firmware at least every 1.5 seconds . when not refreshed on time the wdt overflows, and the part is reset as if the reset pin were pulled high, except that the i/o ram bits will be maintained . 4096 oscillator cycles (or 125 ms ) after the wdt overflow, the mpu will be launched from program address 0x0000. asserting ice_e will deactivate the wdt . 1.5.7 program security when enabled, the security feature limits the ice to global flash erase operations only . all other ice operations are blocked . this guarantees the security of the users mpu and ce program code . security is enabled by mpu code that is executed in a 32 cycle preboot interval before the primary boot sequence begins . once security is enabled, the only way to disable it is to perform a global erase of the flash , followed by a chip reset. 1.5.8 test ports tmuxout pin: one out of 16 digital or 8 analog signals can be selected to be output on the tmuxout pin . the function of the multiplexer is described in the applicable firmware documentation. not recommended 78m6613 dio led v3p3 d 3.3v gnd d r recomme nded r led dio v3p3 d gnd d 3.3v 78m6613 downloaded from: http:///
ds_6613_018 78m6613 data sheet 2 functional description 2.1 theory of operation the energy delivered by a power source into a load can be expressed as: = t dt tit v e 0 )()( t he following formulae apply for wide band mode (true rms ): ? p = (i (t) * v (t)) ? q = (s 2 C p 2 ) ? s = v * i ? v = ? v (t) 2 ? i = ? i (t) 2 for a practical measurement , not only voltage and current amplitudes, but also phase angles and harmonic content may change constantly . thus, simple rms measurements are inherently inaccurat e , and true rms measurements must be utilized . a modern solid - state electricity power and energy measurement ic such as the 78m6613 functions by emulating the integral operation above, i.e. it processes current and voltage samples through an adc at a constant frequency . as long as the adc resolution is high enough and the sample frequency is beyond the harmonic range of interest, the current and voltage samples, multiplied with the time period of sampling will yield an accurate quantity for the m omentary energy . summing up the momentary energy quantities over time will result in accumulated energy. -500 -400 -300 -200 -100 0 100 200 300 400 500 0 5 10 15 20 current [a] voltage [v] energy per interval [ws] accumulated energy [ws] figure 4 : voltage . current, momentary and accumulated energy figure 4 sh ows the shapes of v(t), i(t), the momentary power and the accumulated power, resulting from 50 samples of the voltage and current signals over a period of 20 ms . the application of 240 vac and 100 a results in an accumulation of 480 ws (= 0.133 wh) over the 20 ms period, as indicated by the accumulated power curve. the described sampling method works reliably, even in the presence of dynamic phase shift and harmonic distortion. for actual measurement equations, refer to the applicable firmware documentat ion . downloaded from: http:///
78m6613 data sheet ds_6613_018 2.2 reset behavior reset mode: when the reset pin is pulled high all digital activity stops . the oscillator continue s to run . additionally, all i/o ram bits are set to their default states . once initiated, the reset mode will persist until the reset timer times out . this will occur in 4096 ck32 clock cycles (32768 hz clock cycles from pll block) after reset goes low, at which time the mpu will begin executing its preboot and boot sequences from address 00 . 2.3 data flow the data flow between ce and mpu is shown in figure 5 . in a typical application, the 32 - bit compute engine (ce) sequentially processes the samples from the voltage inputs on pins a0 , a1, a2 , and a3 , performing calculations to measure active power (wh), reactive power (varh), a 2 h, and v 2 h for four - quadrant measurement s . these measurements are then accessed by the mpu, processed further and output using the peripheral devices available to the mpu. figure 5: mpu/ce data flow ce mpu pre - processor post - processor irq processed measurement data i/o ram (configuration ram) samples data downloaded from: http:///
ds_6613_018 78m6613 data sheet 2.4 ce/mpu communication figure 6 shows the functional relationship between ce and mpu. the ce is controlled by the mpu via shared registers in the i/o ram and by registers in the ce dram. the ce outputs two interrupt signals to the mpu to indicate when the ce is actively processing data and when the ce is updating data to the output region of the ce dram. mpu ce interrupts dio serial (uart) samples adc ce_busy xfer_busy mux ctrl. data control i/o ram (configuration ram) figure 6: mpu/ce communication downloaded from: http:///
78m6613 data sheet ds_6613_018 3 a pplication information 3.1 connection of sensors (ct, resistive shunt) figure 7 , figure 8 , and figure 9 s how how resistive voltage dividers, resistive current shunts, and current transformers are connected to the voltage and current inputs of the 78m6613 . figure 7 : resistive voltage divider figure 8 : resistive current shunt figure 9 : current transformer downloaded from: http:///
ds_6613_018 78m6613 data sheet 3.2 temperature measurement measurement of absolute temperature uses the on - chip temperature sensor while applying the following formula: n n n t s n t n t + ? = ) )( ( in the above formula , t is the temperature in c, n(t) is the adc count at temperature t, n n is the adc count at 25c, s n is the sensitivity in lsb/c and t n is +25c. example: at 25c a temperature sensor value of 518,203,584 (n n ) is read by the adc by a 78m 6613 in the 32 - pin qfn package . at an unknown temperature t the value 449,648, 00 0 is read at (n(t)) . the absolute temperature is then determined by dividing both n n and n(t) by 512 to account for the 9 - bit shift of the adc value and then inserting the results into the above formula, using C 2220 for lsb/c: c c t = + ?? = 3.85 25 ) 2220 ( 512 4 518,203,58 -0 449,648,00 3.3 temperature compensation temperature coefficients: the internal voltage reference is calibrated during device manufacture. the temperature coefficients tc1 and tc2 are given as constants that represent typical com ponent behavior (in v/c and v/c 2 , respectively). since tc1 and tc2 are given in v/c and v/c 2 , respectively, the value of the vref voltage (1.195v) has to be taken into account when transitioning to ppm/c and ppm/c 2 . this means t hat ppmc = 26.84*tc1/1.195, and ppmc2 = 1374*tc2/1.195). temperature compensation : t he ce provides the bandgap temperature to the mpu, which then may digitally compensate the power outputs for the temperature dependence of vref . the mpu, not the ce, is entirely in charge of providing temperature compensation . the mpu applies the following formula to determine any gain adjustments . in this formula temp_x is the deviation from nominal or calibration temperature expressed in multiples of 0.1c: 23 2 14 2 2 _ 2 _ 16385 _ ppmc x temp ppmc x temp adj gain ? + ? + = in a power and energy measurement unit, the 78m 6613 is not the only component contributing to temperature de penden cy. a whole range of components (e.g. current transformers, resistor dividers, power sources, filter capacitors) will contribute temperature effects. since the output of the on - chip temperature sensor is accessible to the mpu, temperature - compensation me chanisms with great flexibility are possible (e.g. system - wide temperature correction over the entire unit rather than local to the chip ). downloaded from: http:///
78m6613 data sheet ds_6613_018 3.4 connecting 5v devices all digital input pins of the 78m 6613 are compatible with external 5v devices . i/o pins c onfigured as inputs do not require current - limiting resistors when they are connected to external 5v devices. 3.5 uart (tx/rx) the rx pin should be pulled down by a 10 k ? resistor and op tionally protected by a 100 pf ceramic capacitor, as shown in figure 10 . figure 10 : connections for the rx pin 3.6 reset function and reset pin connections the 78m6613 requires an external reset circuit to drive the reset input pin. the reset is used to prevent the 78m6613 from operating at supply voltages outside the recommended operating conditions. reset ensures the device is set to a known set of initial conditions and that it begins executing instructions from a predetermined starting address. the reset can be forced by applying a high level to the reset pin. the reset input is internally filtered (low - pass filter) in order to eliminate spurious reset conditions that can be triggered in a noisy environment. for this reason the reset pin must be asserted (high) for at least 1 s in order to initiate a reset sequence. the external reset circuitry should be designed in order to hold the reset pin high (active) whenever v3p3d is below normal operating level. refer to section 4.3, recommended operating conditions . figure 11 shows the behavior of the external reset circuitry. tx rx 10k 100pf rx tx tx rx 78m6613 10k 100pf rx tx optional downloaded from: http:///
ds_6613_018 78m6613 data sheet 0.0v v3p3 reset > 1 s > 1 s 3.3v supply voltage (v3p3d/v3p3a) max min typ time figure 11 : 78m6613 external reset behavior the reset signal can be generated in a number of different ways. for example, a voltage superv isory device such as maxims max810s can be used to implement the reset/supply voltage supervisory function as shown in figure 12 . vcc gnd rst v3p3 gnd reset 78m6613 max810s figure 12 : max810s connections to the 78m6613 downloaded from: http:///
78m6613 data sheet ds_6613_018 an alternate solution using discrete components can be used. figure 1 3 shows an implementation using a shunt regulator and two transistors. figure 13 : reset generator based on tl431 shunt regulator as long as v3p3 is below the 2.79v threshold set by the voltage divider of r1 and r2, u1 will not conduct current, the base of q2 will be at the same potential as its emitter, so q1 will be turned off. with no current flowing in the collector of q2, the base of q1 will be low, q1 will be turned off, and reset will track v3p3. when the v3p3 rises above 2.79v, the tl431 starts to conduct, the base of q2 is be pulled low, turning on q2. this drives the base of q1 high, turning q1 on and pulling reset low. the inherent turn - on and turn - off delays of the tl4313 provide the ~1s delay required to ensure proper resetting of the 78m 6613 . 3.7 connecting the emulator port pins it is important to bring out the ice_e pin to the programmi ng interface in order to create a way for reprogramming parts that have the flash secure bit (sfr 0xb2[6]) set . providing access to ice_e ensures that the part can be reset between erase and program cycles, which will enable programming devices to reprogram the part . the reset required is implemented with a watchdog timer reset (i.e. the hardware wdt must be enabled). figure 14 : external components for the emulator interface e_rst e_rxtx e_tclk 62 62 62 1000pf ice_e v3p3 e_rst 78m6613 62 62 62 ice_e 300 downloaded from: http:///
ds_6613_018 78m6613 data sheet 3.8 crystal oscillator the oscillator of the 78m 6613 drives a standard 32.768 khz watch crystal . the oscillator has been designed specifically to handle these crystals and is compatible with their high impedance and limited power handling capability . good layouts will have xin and xout shielded from each other. since the oscillator is self - biasing, an external resistor must not be connected across the crystal. 3.9 flash programming operational or test code can be programmed into the flash memory using either an in - circuit emulator or t he flash programmer module (tfp -2 ) available from m axim . the flash programming procedure uses the e_rst, e_rxtx, and e_tclk pins. 3.10 mpu firmware library any application - specific mpu functions mentioned above are available from m axim as a standard ans i c library and as ansi c source code. the code is pre - programmed in demonstration and evaluation kits for the 78m 6613 ic and can be pre - programmed into engineering ic samples for system evaluation. the application code allow s for quick and efficient evaluation of the ic without having to write firmware or having to purchase an in - circuit emulator (ice). a software licensing agreement (sla) can be signed to receive either the source flash hex file for use in a production environment or (partial) source code and sdk documentation for modification . 3.11 measurement calibration once the 78m 6613 power and energy measurement device has been installed in a measurement system, it is typically calibrated for tolerances of the current sensors, voltage dividers and s ignal conditioning components. the device can be calibrated using a single gain and a single phase adjustment factors accessible to the ce. the gain adjustment is used to compensate for tolerances of components used for signal conditioning, especially the resistive components. phase adjustment is provided to compensate for phase shifts introduced by certain types of current sensors. due to the flexibility of the mpu firmware, any calibration method, such as calibration based on energy, or current and voltage can be implemented. it is also possible to implement segment - wise calibration (depending on current range). m axim software supports a quick cal method . downloaded from: http:///
78m6613 data sheet ds_6613_018 4 electrical specifications 4.1 absolute maximum ratings supplies and ground pins: v3p3 - 0.5 v to 4.6 v gnd d, gnda - 0.5 v to +0.5 v analog output pins: vref - 10 ma to +10 ma , - 0.5 v to v3p3 +0.5 v analog input pins: a0 , a1 , a2 , a3 - 10 ma to +10 ma - 0.5 v to v3p3 +0.5 v xin, xout - 10 ma to +10 ma - 0.5 v to 3.0 v all other pins: configured as digital inputs - 10 ma to +10 ma, - 0.5 to 6 v configured as digital outputs - 15 ma to +15 ma, - 0.5 v to v3p3d+0.5 v all other pins - 0.5 v to v3p3d+0.5 v operating junction temperature (peak, 100 ms ) + 140 c operating junction temperature (continuous) + 12 5 c storage temperature - 45 c to +165 c soldering temperature ( 10 second duration ) + 250 c esd stress on all pins 4 kv stresses beyond absolute maximum ratings may cause permanent damage to the device . these are stress ratings only and functional operation at these or any other conditions beyond those indicated under recommended operating conditions is not implied . exposure to absolute - maximum - rated conditions for extended periods may affect device reliability . all voltages are with respect to gnd. downloaded from: http:///
ds_6613_018 78m6613 data sheet 4.2 recommended external components name from to function value unit c1 v3p3a gnd a bypass capacitor for 3.3v supply . 0.1 1 0% f csys v3p3d gndd bypass capacitor for v3p3 d. 0.1 10% f xtal xin xout 32.768 k hz crystal C electrically similar to ecs .327 - 12.5 - 17x or vishay xt26t, load capaci tance 12.5 pf . 32.768 khz cxs ? xin gnd load capacitor for crystal (exact value depends on crystal specifications and parasitic capacitance of board). 27 10% pf cxl ? xo ut gnd 27 10% pf ? depending on trace capacitance, higher or lower values for cxs and cxl must be used . capacitance from xin to gnd and xout to gnd (combining pin, trace and crystal capacitance) should be 35 pf to 37 pf . 4.3 recommended operating condition s parameter condition min typ max unit 3.3v supply voltage ( v3p3) normal operation 3.0 3.3 3.6 v operating temperature - 40 +85 oc 4.4 p erformance specifications 4.4.1 input logic levels parameter condition min typ max unit digital high - level input voltage, v ih 2 v digital low - level input voltage, v il 0.8 v input pull - up current, i il e_rxtx, e_rst, cktest other digital inputs vin=0v, ice_e=1 10 10 -1 0 100 100 1 a a a input pull down current, i ih ice_e other digital inputs vin= v3p3 10 -1 0 100 1 a a 4.4.2 output logic levels parameter condition min typ max unit digital high - level output voltage v oh i load = 1 ma v3p3 C 0.4 v i load = 15 ma v3p3- 0.6 1 v di gital low - level output voltage v ol i load = 1 ma 0 0.4 v i load = 15 ma 0.8 1 v 1 guaranteed by design ; not production tested . downloaded from: http:///
78m6613 data sheet ds_6613_018 4.4.3 s upply current parameter condition min typ max unit v3p3a + v3p3 d current normal operation, v3p3 =3.3v , ice disabled 8 .1 1 0.3 ma v3p3 a + v3p3 d current vs. mpu clock frequency same conditions as above 0.5 ma/ mhz v3p3 a + v3p d current, write flash normal operation as above, except write flash at maximum rate, adc & ce disabled 9.1 10 ma 4.4.4 crystal oscillator parameter con dition min typ max unit maximum output power to crystal crystal connected 1 w xin to xout capacitance 3 pf capacitance to gnd xin xout 5 5 pf pf 4.4.5 vref unless otherwise specified, vref_dis =0 parameter condition min t yp max unit vref output voltage, vnom(25) ta = 22oc 1.193 1.195 1.197 v vref chop step 50 mv vref output impedance vref_cal =1, i load = 10 a, - 10 a 2.5 k vnom definition * 2 ) 22 ( 1 ) 22 () 22 ( )( 2 tc t tc t vref t vnom ? + ? + = v vref temperature coefficients tc1 tc2 124.4 - 2. 435*trimt - 0. 265 + 0.00106*trimt v/oc v/c 2 vref aging 2 5 ppm/ year vref(t) deviation from vnom(t) 62 10 )( )( 6 vnom t vnom t vref ? ta = - 40oc to +85oc - 40 1 +40 1 ppm/o c * this relationship describes the nominal behavior of vref at different temperatures. downloaded from: http:///
ds_6613_018 78m6613 data sheet 4.4.6 adc converter , v3p3 r eferenced vref_dis =0, lsb values do not include the 9 - bit left shift at ce input. parameter condition min typ max unit recommended input range (vin- v3p3a ) - 250 250 mv peak vo ltage to current crosstalk: ) cos( * 10 6 vcrosstalk vin vin vcrosstalk ? vin = 200 mv peak, 65 hz, on a0 vcrosstalk = largest measurement on a1 or a3 - 10 1 10 1 v/v thd (first 10 harmonics) 250 mv - pk 20 mv - pk vin=65 hz, 64 kpts fft, blackman - harris window - 75 - 90 db db input impedance vin=65 hz 40 90 k temperature coefficient of input impedance vin=65 hz 1.7 /c lsb size fir_ len=0 fir_len=1 357 151 nv/lsb digital full scale fir_ len=0 fir_len=1 + 884736 + 2097152 lsb adc gain error vs %power supply variat ion 3.3/3 3 100 / 357 10 6 a p v v nv nout in pk ? ? vin=200 mv pk, 65 hz v3p3 =3.0v, 3.6v 50 ppm/% input offset (vin - v3p3a ) - 10 10 mv 4.4.7 temperature sensor parameter condition min typ max unit nominal sensitivity (s n ) fir _ len=0 fir_len=1 - 66 9 - 1585 lsb/oc nominal (n n ) ? fir _ len=0 fir_len=1 + 429301 + 1017558 lsb temperature error ? ?? ? ? ?? ? + ? ? = n n n t s n t n t err ) )(( t a = - 40oc to +85oc tn = 25c - 10 1 +10 1 oc ? n n is measured at t n during calibration and is stored in mpu or ce for use in temperature calculations. 1 guaranteed by des ign ; not production tested . downloaded from: http:///
78m6613 data sheet ds_6613_018 4.5 timing s pecifications 4.5.1 ram and flash memory parameter condition min typ max unit ce dram wait states ckmpu = 4.9 152 mhz 5 cycles ckmpu = 1.25 mhz 2 cycles ckmpu = 614 khz 1 cycles flash write cycles - 40 c to +85 c 20,000 cycles flash data retention 25 c 100 years flash data retention 85 c 10 years flash byte writes between page or mass erase operations 2 cycles 4.5.2 reset parameter condition min typ max unit reset pulse fall time 1 s reset pulse width 5 s downloaded from: http:///
ds_6613_018 78m6613 data sheet 4.5.3 typical performance data - 0.5 - 0.4 - 0.3 - 0.2 - 0.1 0 0.1 0.2 0.3 0.4 0.5 0.01 0.1 1 10 accuracy (%) current (a) wh accuracy (%) wh accuracy (%) figure 15 : wh accuracy, 10 ma to 20 a at 12 0 v /6 0 hz and room temperature using a 4 m ? current shunt relative accuracy over temperature -30 -20 -10 0 10 20 30 40 -60 -40 -20 0 20 40 60 80 100 temperature [c] accuracy [ppm/c] figure 16 : t ypical measurement accuracy over temperature relative to 25c downloaded from: http:///
78m6613 data sheet ds_6613_018 5 packaging 5.1 pinout v3p3a gnda reset rx dio8 dio7 dio6 dio5 32 31 30 29 28 27 26 25 a1 1 24 ice_e a3 2 23 gndd a2 3 22 dio4 a0 4 21 dio19 vref 5 20 dio16 xin 6 19 dio15 test 7 18 dio14 xout 8 17 dio17 9 10 11 12 13 14 15 16 cktest v3p3d n/c e_tclk e_rst e_rxtx tmuxout tx figure 17 : 32 - pin qfn pinout downloaded from: http:///
ds_6613_018 78m6613 data sheet 5.2 package o utline ( qfn 32 ) note: controlling dimensions are in mm . figure 18 : package outline (qfn 32 ) 2.5 5 2.5 5 top view 1 2 3 0. 85 nom . / 0.9 max . 0. 00 / 0. 005 0. 20 ref . seating plane side view 0. 2 min . 0. 35 / 0. 45 1. 5 / 1.6 3. 0 / 3.2 0. 18 / 0.3 bottom view 1 2 3 0.5 0.5 3.0 / 3.2 1.5 / 1.6 0.35 / 0.45 chamfered 0. 30 downloaded from: http:///
78m6613 data sheet ds_6613_018 5.3 recommended pcb land pattern for the qfn - 32 package e a d g x x e y y a d g s ymbol description min typ max e lead pitch 0.50 mm x 0.28 mm 0.28 mm y 0.69 mm d see note 1 3.00 mm a 3.78 mm g 3.93 mm note 1: do not place unmasked vias in region denoted by dimension d. note 2: soldering of bottom internal pad not required for proper operation of either commercial or industrial temperature rated versions. figure 19 : recommended pcb land pattern dimensions downloaded from: http:///
ds_6613_018 78m6613 data sheet 6 pin descriptions 6.1 power/ground pins name type circuit description gnda gndd p C th ese pin s should be connected directly to the ground plane. v3p3a v3p3d p C a 3.3v power supply should be connected to th ese pin s. 6.2 analog pins name type circuit description a0 , a 1, a2, a3 i 5 sense inputs: these pins are voltage inputs to the internal a/d converter. typically, they are connected to either the outputs of current sensors or the outputs of resistor dividers (voltage sensors) . unused pins must be connected to v3p3 . vref o 8 voltage reference for the adc . this pin is left un connected. never use as an external reference. xin xout i 7 crystal inputs . a 32 khz crystal should be connected across these pins . typically, a 27 pf capacitor is also connected from each pin to gnd . it is important to minimize the capacitance between these pins . see the crystal manufacturer datasheet for details. pin types: p = power, o = output, i = input, i/o = input/output the circuit number denotes the equivalent circuit, as specified under i/o equivalent circuits. downloaded from: http:///
78m6613 data sheet ds_6613_018 6.3 digital pins name type circuit description dio4 dio5 dio6 dio7 dio8 dio14 dio1 5 dio1 6 dio17 dio19 i/o 3, 4 dio pins . if unused, these pins must be configured as dios and set to outputs by the firmware . e_rxtx , e_rst i/o 1, 4 e mulator port pins (when ice_e pulled high) . e_tclk o 4 ice_e i 2 ice enable . when zero, e_rst, e_tclk, and e_rxtx are disable d. for production units, this pin should be pulled to gnd to disable the emulator port . this pin should be brought out to the programming inter face in order to create a way for reprogramming parts that have the secure bit set. cktest o 4 clock pll output . tmuxout o 4 digital output test multiplexer . reset i 3 this input pin resets the chip into a known state . for normal operation, this pin should be pulled low. to force the device into reset state, it should be pulled high. refer to section 3.6 for reset pin connections, use, and relevant external circuitry. rx i 3 uart input . if unused, this pin must be terminated to v3p3 or gnd . tx o 4 uart output. test i 7 enables production test . must be grounded in normal operation. pin types: p = power, o = output, i = input, i/o = input/output the circuit number denotes the equivalent circuit, as specified on the following page. downloaded from: http:///
ds_6613_018 78m6613 data sheet 7 i/o equivalent circuits figure 20 : i/o equivalent circuits digital input equivalent circuit type 1: standard digital input or pin configured as dio input with internal pull - up gnd 110 k v3p3 cmos input v3p3 digital input pin cmos output gnd v3p3 gnd v3p3 digital output equivalent circuit type 4: standard digital output or pin configured as dio output digital output pin to mux gnd v3p3 analog input equivalent circuit type 5 : adc input analog input pin vref equivalent circuit type 8: vref from internal reference gnd v3p3 vref pin oscillator equivalent circuit type 7: oscillator i /o to oscillator gnd oscillator pin digital input type 2: pin configured as dio input with internal pull - down gnd 110 k gnd cmos input v3p3 digital input pin digital input type 3: standard digital input or pin configured as dio input gnd cmos input v3p3 digital input pin comparator input equivalent circuit type 6: comparator input gnd v3p3 to comparator comparator input pin downloaded from: http:///
78m6613 data sheet ds_6613_018 8 ordering information part pa ckage option ordering number ic marking 78m6613 32 - pin qfn (lead(pb) - free) bulk 78m6613 - im/f 78m6613 - im tape & reel 78m6613 - imr/f * programmed, bulk 78m6613 - im/f/p * programmed, tape & reel 78m6613 - imr/f/p *contact the factory for more information on programmed part options. 9 contact information for more information about maxim products or to check the availability of the 78m661 3, contact technical support at www.maxim - ic.com/support . downloaded from: http:///
ds_6613_018 78m6613 data sheet revisi on history revision number revision date description pages changed 1.0 11 / 10 first publication. ? 1.1 3/11 in section 6.3, corrected the description of the reset pin. 30 2 1 /1 2 added maxim logo. 1 33 maxim integrated 160 rio robles, san jose, ca 95134 usa 1-408-601-1000 maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. ? 2012 maxim integrated the maxim logo and maxim integrated are trademarks of maxim integrated products, inc. downloaded from: http:///

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