true rms to dc converter most current sensors produce outputs that are instantaneous representations of the measured currents. for complex or ac waveshapes there may be a requirement to convert the outputs to true rms values. rms converters available from maxim are designed to accept complex input waveforms containing ac and dc components. they can be operated from either a single or dual supplies. the converters are designated mx536a/mx636 . both devices draw less than 1 ma of quiescent supply current, making them ideal for battery-powered applications. they exhibit >1mhz bandwidth and <.5% ac - curacy. (www.maxim-ic.com) create -12vdc from +12vdc texas instrument?s pt78nr112 creates a negative output voltage from +12vdc input. these easy-to-use, 3-terminal, integrated switching regulators have maximum output power of 5 watts and a negative output voltage that is laser trimmed. they also have excellent line and load regulation. they can be used with current sensors that reguire 12vdc power supplies. (www.ti.com) definitions response time response time is defned as the delay between the instant the sensed current reaches 90% of its fnal value and the instant the sensor output signal reaches 90% of fnal value as illustrated in figure 7. for open loop sensors response time and di/dt ratings depend primarily upon the slew rate of the amplifer. di/dt accurately followed the linear rate of change in current that the sensor can accurately measure. linearity output deviation from a straight line response to the current being measured. 5 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? figure 7
for technical support and more information, see inside back cover or visit www.ti.com/powertrends pt78nr100 series standard application c1 = required 100f electrolytic (1) c2 = required 100f electrolytic (1) ordering information pt78nr1 pin-out information pin function 1+v i n 2-v out 3 gnd ? negative output from positive input ? wide input range ? self-contained inductor ? short circuit protection ? over-temperature protection ? fast transient response the pt78nr100 series creates a negative output voltage from a posi- tive input voltage greater than 7v. these easy-to-use, 3-terminal, inte- grated switching regulators (isrs) have maximum output power of 5 watts and a negative output voltage that is laser trimmed. they also have excellent line and load regulation. 1 amp plus to minus voltage integrated switching regulator pt78nr100 + -vout com com vin 1 3 2 c2 c1 + xx y pkg style 500 slts058b (revised 8/31/2000) output voltage 03 = -3.0 volts 05 = -5.0 volts 52 = -5.2 volts 06 = -6.0 volts 07 = -7.0 volts 08 = -8.0 volts 09 = -9.0 volts 10 = -10.0 volts 12 = -12.0 volts 14 = -13.9 volts 15 = -15.0 volts package suffix v = vertical mount s = surface mount h = horizontal mount specifications characteristics pt78nr100 series (t a = 25c unless noted) symbols conditions min typ max units output current i o over v in range v o =-5v 0.05 (2) 1.00 v o =-6v 0.05 (2) 0.8 v o =-7, -8, -9v 0.05 (2) 0.55 a v o =-10v 0.05 (2) 0.5 v o =-12v 0.05 (2) 0.40 v o =-13.9, -15v 0.05 (2) 0.30 short circuit current i sc v in =10v 4 i max apk inrush current i ir v in =10v 4 a t ir on start-up 0.5 msec input voltage range v in 0.1 i o i max v o =-5v 7 25 v v o =-6, -7, -8, -9v 7 21 v v o =-10, -12v 7 18 v v o =-13.9, -15v 7 15 v output voltage tolerance d v o over v in range 1.0 3.0 %v o t a =-20c to +70c line regulation reg line over v in range 0.5 1.0 %v o load regulation reg load 0.1 i o i max 0.5 1.0 %v o v o ripple/noise v n v in =10v, i o =i max 2%v o transient response t tr 50% load change 100 250 sec (with 100f output cap) v o over/undershoot 5.0 %v o efficiency h v in =10v, i o =0.5 i max, v o = -5v 75 % switching frequency ? o over v in and i o ranges 600 650 700 khz absolute maximum t a free air convection, (40-60lfm) -40 +85 (3) c operating temperaturte range over v in range thermal resistance q ja free air convection, (40-60lfm) 45 c/w storage temperature t s -40 +125 c mechanical shock per mil-std-883d, method 2002.3 500 gs mechanical vibration per mil-std-883d, method 2007.2, 5 gs 20-2000 hz, soldered in a pc board weight 6.5 grams notes: (1) the pt78nr100 series requires a 100f electrolytic or tantalum capacitor at both the input and output for proper operation in all applications. the input capacitor, c 1 must have a ripple current rating 3 600 marms, and an esr 0.2 w . (2) the isr will operate down to no load with reduced specifications. (3) see thermal derating chart.
for technical support and more information, see inside back cover or visit www.ti.com/powertrends typical characteristics 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 7 101316192225 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 7 10131619 0 0.1 0.2 0.3 0.4 0.5 0.6 7 111519 pt78nr105 -5.0 vdc (see note a) pt78nr109 -9.0 vdc (see note a) pt78nr112 -12.0 vdc (see note a) efficiency vs output current ripple vs output current thermal derating (t a ) (see note b) power dissipation vs output current efficiency - % ripple-(mv) iout-(amps) pd-(watts) efficiency - % ripple-(mv) iout-(amps) iout-(amps) pd-(watts) note a: all data listed in the above graphs, except for derating data, has been developed from actual products tested at 25c. this dat a is considered typical data for the isr. note b: thermal derating graphs are developed in free air convection cooling of 40-60 lfm. (see thermal application notes.) iout-(amps) iout-(amps) iout-(amps) iout-(amps) iout-(amps) iout-(amps) vin-(volts) vin-(volts) vin-(volts) 40 50 60 70 80 90 100 0 0.2 0.4 0.6 0.8 1 7.0v 12.0v 15.0v 20.0v 25.0v vin 0 40 80 120 160 200 0 0.2 0.4 0.6 0.8 1 25.0v 20.0v 15.0v 12.0v 7.0v vin 85c 60c 85c 70c 85c 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 0.1 0.2 0.3 0.4 0.5 21.0v 18.0v 15.0v 12.0v 7.0v vin 40 50 60 70 80 90 100 0 0.1 0.2 0.3 0.4 0.5 7.0v 12.0v 15.0v 18.0v 21.0v vin 0 40 80 120 160 200 0 0.1 0.2 0.3 0.4 0.5 21.0v 18.0v 15.0v 12.0v 7.0v vin 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0 0.2 0.4 0.6 0.8 1 25.0v 20.0v 15.0v 12.0v 7.0v vin 70c 70c efficiency vs output current efficiency vs output current ripple vs output current ripple vs output current thermal derating (t a ) (see note b) thermal derating (t a ) (see note b) power dissipation vs output current power dissipation vs output current pt78nr100 series 1 amp plus to minus voltage integrated switching regulator 40 50 60 70 80 90 100 0 0.1 0.2 0.3 0.4 iout-(amps) efficiency - % 7.0v 9.0v 12.0v 15.0v 18.0v v in 0 50 100 150 200 250 0 0.1 0.2 0.3 0.4 iout-(amps) ripple - mv 18.0v 15.0v 12.0v 9.0v 7.0v v in 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 0.1 0.2 0.3 0.4 iout-(amps) pd - watts 18.0v 15.0v 12.0v 9.0v 7.0v v in
important notice texas instruments and its subsidiaries (ti) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. all products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. ti warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with ti's standard warranty. testing and other quality control techniques are utilized to the extent ti deems necessary to support this warranty. specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. customers are responsible for their applications using ti components. in order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. ti assumes no liability for applications assistance or customer product design. ti does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of ti covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. ti's publication of information regarding any third party's products or services does not constitute ti's approval, warranty or endorsement thereof. copyright ? 2000, texas instruments incorporated
|
