general description the MAX78700 is an isolated analog-to-digital converter (adc) for use with a compatible max78xxx energy mea - surement processor. the device provides current and voltage measurements to the host while the host pro - vides control, command, and power to the MAX78700. a pulse transformer provides the isolated data and power path between the device and host, eliminating the need for additional isolation components in the measurement subsystem. applications smart grid-friendly equipment lighting control systems commercial and industrial automation renewable energy systems electric vehicle charging systems benefts and features better than 0.5% watt-hour accuracy over wide dynamic range using a single calibration point ? high-resolution delta-sigma adc ? factory-trimmed voltage reference and die temperature sensor simplified system architecture ? no power supply required ? fully powered by the host with the isolation transformer ? eliminates data isolation components ? reduced form factor and bill of materials small 10-pin max? package 19-6565; rev 0; 12/12 ordering information appears at end of data sheet. for related parts and recommended products to use with this part, refer to www.maximintegrated.com/MAX78700.related . block diagram max is a registered trademark of maxim integrated products, inc. i n a p i n a n i n b p i n b n i s o p i s o n energy measurement processor ?host? r esistive sensors power, timing, control a d c d ata mux a d c system power host interface MAX78700 MAX78700 multichannel, isolated, precision adc
maxim integrated 2 (all voltages with respect to gnd.) voltage range inan, inap, inbp, inbn ............. -0.5v to +4.6v voltage range isop, ison .................................. -0.5v to +4.6v operating temperature range ........................... -40c to +85c operating junction temperature (peak) ......................... +140c operating junction temperature (peak, 100ms) ............ +140c operating junction temperature (continuous) ............... +125c storage temperature ........................................ -45c to +165c lead temperature (soldering, 10s) ................................. +300c soldering temperature (reflow) ....................................... +260c stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to ab solute maximum rating conditions for extended periods may affect device reliability. absolute maximum ratings recommended external components performance specifcations (limits are 100% production tested at t a = +22 c. limits over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.) note 1: guaranteed by design, not subject to test. name from to function value unit c1 v cc gnd bypass capacitor for supply 0.5 f parameter symbol conditions min typ max units usable input range v in inap, inan, inbp, inbn v cc - 250 v cc + 250 mv peak total harmonic distortion thd first 10 harmonics, f in = 65hz, v in = 20mv, 64kpts fft, blackman-harris window -85 db input impedance f in = 65hz 20 90 k temperature coeffcient of input impedance f in = 65hz (note 1) 1.7 /c adc gain error vs. % power-supply variation v in = 200mv p-p , 65hz, v cc = 3.0v, 3.6v 50 ppm/% input offset -10 +10 mv 6 pk in 10 nout 357nv / v 100 vcc / 3.3 ? ? www.maximintegrated.com MAX78700 multichannel, isolated, precision adc
maxim integrated 3 pin description pin confguration pin name function 1 inbn channel b adc negative input 2 inbp channel b adc positive input 3 testenb enables the test modes. must be grounded in normal operation. 4 ison transformer negative 5 isop transformer positive 6 tmux host-controlled dio 7 v cc output of the rectifer block 8 gnd ground. the 0.5f capacitor from v cc to gnd must be connected to this pin. 9 inap channel a adc positive input 10 inan channel a adc negative input 10 2 3 4 5 9 8 7 6 i n ap g n d v c c t mu x isop ison t est en b i n bp max top view + MAX78700 1 i n an i n bn www.maximintegrated.com MAX78700 multichannel, isolated, precision adc
maxim integrated 4 detailed description the MAX78700 is an isolated current and voltage ana - log-to-digital converter (adc) that is compatible with max78xxx hosts. the device digitizes low-level signals from shunt resistor type current sensors and resistive divider voltage measurements. the device continuously sends adc data to the host. the host can request the device to return certain ancillary data such as trim information and die temperature data. the MAX78700 communicates with the host through a pulse transformer to provide isolation from the high-voltage power domain. figure 1 shows a block diagram of the device with a brief description of various functional blocks. rectifer the active rectifier in the device rectifies the power pulses received from the host through the isolation transformer to create the v cc voltage. a 2.5v regulator block powers all the digital blocks of the chip except the pll and iso_int, which are powered by v cc . iso_int the isolated interface block receives the incoming data from the host and transmits data back to the host through the isolation transformer. pll the pll locks to the incoming power pulses to create ref - erence clocks for the adc and communications interface to the host. adc maxim integrateds proven delta-sigma adc digitizes the voltage and current-sense voltages. bandgap the device includes an on-chip precision bandgap volt - age reference that incorporates auto-zero techniques as well as production trims to minimize errors caused by component mismatch and drift. the result is a voltage output with a predictable temperature coefficient that is compensated in firmware by the host. figure 1. functional diagram m u x inbn inbp inan inap t m u x fi r v r e f v b i a s g e n i b i a s g e n m u x c o n t r o l t e m p s e n s e t e s t e n b a dc MAX78700 rectifier p l l t r i m o t p g n d isop ison v c c 2.5v reg 2.5v i s o_i n t i n te r fa c e + m o d e c o n tr o l c l o c k g e n www.maximintegrated.com MAX78700 multichannel, isolated, precision adc
maxim integrated 5 package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. +denotes a lead(pb)-free/rohs-compliant package. t = tape and reel. ordering information temperature and power-supply voltage measurement the device includes an on-chip temperature sensor. the voltage from this sensor is measured by the adc and sent to the host. during manufacturing test, the circuit is calibrated by measuring the voltage at room temperature and storing the value in the otp memory. a resistor-divider scales the rectified power-supply voltage, v cc , to match the input range of the adc. the adc mea - sures the scaled voltage and the value is sent to the host. package type package code outline no. land pattern no. 10 max u10+2 21-0061 90-0330 part temp range pin-package MAX78700+a00 -40c to +85c 10 max MAX78700+a00t -40c to +85c 10 max www.maximintegrated.com MAX78700 multichannel, isolated, precision adc
? 2012 maxim integrated products, inc. 6 revision history revision number revision date description pages changed 0 12/12 initial release maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and specifcations 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. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. MAX78700 multichannel, isolated, precision adc for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com.
|
