z to92 (plastic package) . operates from 1v to 40v . 0.02% v current regulation . programmable from 1 m a to 10ma . 3% initial accuracy description the LM134/lm234/lm334 are 3-terminal adjust- able current sources characterized by : - an operating current range of 10000 : 1 - an excellent current regulation - a wide dynamic voltage range of 1v to 40v the current is determined by an external resistor without requiring other external components. reverse voltages of up to 20v will only draw a cur- rent of several microamperes. this enables the circuit to operate as a rectifier and as a source of cur- rent in a.c. applications. for the LM134/lm234/lm334, the voltage on the control pin is 64mv at +25 o c and is directly propor- tional to the absolute temperature ( o k). the simplest external resistor connection generates a current with ? 0.33%/ o c temperature dependence. zero drift can be obtained by adding an additional resistor and a diode to the external circuit. pin connections d so8 (plastic micropackage) v + adj v - 2 1 3 to92 (bottom view) LM134-lm234 lm334 three terminal adjustable current sources 876 5 123 4 nc nc v nc - adj nc nc v + so8 (top view) order codes part num- ber temperature range package zd LM134 C55 o c, +125 o c lm234 C25 o c, +100 o c lm334 0 o c, +70 o c example : LM134z october 1997 1/10
q3 q4 q5 q6 q1 q2 c1 50pf adj v v schematic diagram absolute maximum rating symbol parameter LM134 - lm234 lm334 unit voltage v + to v C forward reverse 40 20 30 20 v v adj - adj pin to v C voltage 5 5 v i set set current 10 10 ma p tot power dissipation 400 400 mw t stg storage temperature range C65 to +150 o c t oper operating free-air temperature range LM134 lm234 lm334 C55 to +125 C25 to +100 0 to +70 o c LM134-lm234-lm334 2/10
electrical characteristics t j = +25 o c with pulse testing so that junction temperature does not change during testing (unless otherwise specified) parameter LM134 - lm234 lm334 unit min. typ. max. min. typ. max. set current error (v + = +2.5v) - (note 1) 10 m a i set 1ma 1ma i set 5ma 2 m a i set 10 m a 3 5 8 6 8 12 % ratio of set current to v C current 10 m a i set 1ma 1ma i set 5ma 2 m a i set 10 m a 14 18 14 14 23 14 18 14 14 26 minimum operating voltage 2 m a i set 100 m a 100 m a i set 1ma 1ma i set 5ma 0.8 0.9 1 0.8 0.9 1 v average change in set current with input voltage 2 m a i set 1ma +1.5v v + +5v +5v v + +40v 1ma i set 5ma +1.5v v + + +5v +5v v + +40v 0.02 0.01 0.03 0.02 0.05 0.03 0.02 0.01 0.03 0.02 0.1 0.05 % / v temperature dependence of set current - (note 2) 25 m a i set 1ma 0.96 t t 1.04 t 0.96 t t 1.04 t effective shunt capacitance 15 15 pf notes : 1. set current is the current flowing into thev + pin. it is determined by the following formula iset = 67.7mv/r set (t j = +25 o c). set current error is expressed as a percent deviation from this amount. 2. i set is directly proportional to absolute temperature ( o k). i set at any temperature can be calculated from i set = i o (t/t o ) where i o is iset measured at t o ( o k). LM134-lm234-lm334 3/10
LM134-lm234-lm334 4/10
application hint slew rate at slew rates above a threshold (see curve) the LM134, lm234, lm334 can have a non-linear cur- rent characteristic. the slew rate at which this takes place is directly proportional to i set . at i set = 10 m a, dv/dt max. = 0.01v/ m s ; at i set = 1ma, dv/dt max. = 1v/ m s. slew rates of more than 1v/ m s do not dam- age the circuit nor do they produce high currents. thermal effects internal heating can have a significant effect on cur- rent regulation for an i set above 100 m a. for exam- ple, each increase of 1v in the voltage across the LM134 at i set = 1ma will increase the junction tem- perature by ? 0.4 o c (in still air). the output current (i set ) has a temperature coefficient of about 0.33%/ o c. thus the change in current due to the in- crease in temperature will be (0.4) (0.33) = 0.132%. this is a degradation of 10 : 1 in regulation versus the true electrical effects. thermal effects should be taken into account when d.c. regulation is critical and i set is higher than 100 m a. the dissipation of the connections of cb-97 package can reduce this ther- mal effect by a coefficient of more than 3. shunt capacitance in certain applications, the 15pf value for the shunt capacitance should be reduced : - because of loading problems, - because of limitation of the output impedance of the current source in a.c. applications. this reduc- tion of the capacitance can be easily carried out by adding a fet as indicated in the typical applications. the value of this capacitance can be reduced by at least 3pf and regulation can be improved by an or- der of magnitude without any modification of the d.c. characteristics (except for the minimum input volt- age). noise the current noise produced by LM134, lm234, lm334 is about 4 times that of a transistor. if the LM134, lm234, lm334 is utilized as an active load for a transistor amplifier, the noise at the input will increase by about 12db. in most cases this is ac- ceptable, and a single amplifier can be built with a voltage gain higher than 2000. lead resistance the sense voltage which determines the current of the LM134, lm234, lm334, is less than 100mv. at this level, the effects of the thermocouple and the connection resistance should be reduced by locat- ing the current setting resistor close to the device. do not use sockets for the ics. a contact resistance of 0.7 w is sufficient to decrease the output current by 1% at the 1ma level. sensing temperature the LM134, lm234, lm334 are excellent remote controlled temperature sensors because their op- eration as sources of current preserves their accu- racy even in the case of long connecting wires. the output current is directly proportional to the absolute temperature in degrees kelvin according to the fol- lowing equation. i set = ( 227 m v/ o k ) ( t ) r set the calibration of the LM134, lm234, lm334 is sim- plified by the fact that most of the initial accuracy is due to gain limitation (slope error) and not an offset. gain adjustment is a one point trim because the out- put of the device extrapolates to zero at 0 o k. this particularity of the LM134, lm234, lm334 is il- lustrated in the above diagram. line abc represents the sensor current before adjustment and line abc represents the desired output. an adjustment of the gain provided at t2 will move the output from b to b and will correct the slope at the same time so that the output at t1 and t3 will be correct. this gain ad- justment can be carried out by means of r set or the load resistor utilized in the circuit. after adjustment, the slope error should be less than 1%. a low tem- perature coefficient for r set is necessary to keep this accuracy. a 33ppm/ o c temperature drift of r set will give an error of 1% on the slope because the resis- tance follows the same temperature variations as the LM134, lm234, lm334. three wires are re- quired to isolate r set from the LM134, lm234, lm334. since this solution is not recommended. metal-film resistors with a drift less than 20ppm/ o c are now available. wirewound resistors can be util- ized when very high stability is required. t1 t2 t3 0?k i set desired output initial output c b a a' b' c' LM134-lm234-lm334 5/10
adj v i v set r v v i typical applications figure 1 : basic 2-terminal current source adj v i v set r v r1* v i * for 10% adjustment, select rset 10% high and make r1 ? 3 rset figure 2 : alternate trimming technique adj v i v set r v r l v o v o = (i set ) (r l ) = 10mv/ o k r set = 230 w r l = 10k w figure 3 : terminating remote sensor for voltage output adj r set r1* r set 10 d1 1n 457 v v i i v i v * select ratio of r1 to r set to obtain zero drift i + ? 2i set figure 4 : zero temperature coefficient current source LM134-lm234-lm334 6/10
v adj v o v r3 r2 r1 v > 4.8v i c1 r1 = 230 w , 1% v o = 10mv / o k r2 = 10k w , 1% z o 100 w r3 = 600 w output impedance of the LM134, lm234, lm334 at the "adj" pin is approximately - r o w 16 where r o is the equiva- lent external resistance connected to the v - pin. this negative resistance can be reduced by a factor of 5 or more by inserting an equivalent resistor in series with the output figure 5 : low output im pedance thermometer c1 r1 r2 v i v adj v o v r3 r4 r1 = 15k w r2 = 300 w r3 = 100 w r4 = 4.5k w c1 = 2.2nf v o = 10mv/ o k z o 2 w figure 6 : low output impedance thermometer adj v i v set r v v i 1 m a ua776 r set = 68k w figure 7 : micropower bias adj v i v v c1 r2 v o lm136 r1 2n2905 r1 = 1.5k w r2 = 120 w c1 = 0.1 m f i o 3ma v i + 3 vref +200mv v o = v z +64mv ( +25 o c) figure 8 : low input voltage reference driver LM134-lm234-lm334 7/10
adj v i v set r v op amp c1* * use minimum value required to ensure stability of protected circuit figure 9 : in-line current limiter adj v i v v r set v i q* i set v > 1.2v ds * select q to ensure at least 1v across the LM134, lm234, lm334. v p (1 C i set /i dss ) 3 1.2v figure 10 : fet cascading for low capacitance LM134-lm234-lm334 8/10
pm-so8.eps package mechanical data 8 pins - plastic micropackage (so) dimensions millimeters inches min. typ. max. min. typ. max. a 1.75 0.069 a1 0.1 0.25 0.004 0.010 a2 1.65 0.065 a3 0.65 0.85 0.026 0.033 b 0.35 0.48 0.014 0.019 b1 0.19 0.25 0.007 0.010 c 0.25 0.5 0.010 0.020 c1 45 o (typ.) d 4.8 5.0 0.189 0.197 e 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 3.81 0.150 f 3.8 4.0 0.150 0.157 l 0.4 1.27 0.016 0.050 m 0.6 0.024 s8 o (max.) so8.tbl LM134-lm234-lm334 9/10
pm-to92.img package mechanical data 3 pins - plastic package to92 information furnished is believed to be accurate and reliable. however, sgs-thomson microelectronics assumes no responsi- bility for the consequences of use of such information nor for any infringement of patents or other rights of third parties whi ch may result from its use. no license is granted by implication or otherwise under any patent or patent rights of sgs-thomson microelectronics. specification mentioned in this publication are subject to change without notice. this publication supersedes and replaces all information previously suppli ed. sgs-thomson microelectronics products are not authorized for use as critical components in life support devices or systems wit hout express written approval of sgs-thomson microelectronics. ? 1997 sgs-thomson microelectronics C printed in italy C all rights reserved sgs-thomson microelectronics group of companies australia - brazil - canada - china - france - germany - hong kong - italy - japan - korea - malaysia - malta - morocco the netherlands - singapore - spain - sweden - switzerland - taiwan - thailand - united kingdom - u.s.a. order code : dimensions millimeters inches min. typ. max. min. typ. max. l 1.27 0.05 b 3.2 3.7 4.2 0.126 0.1457 0.1654 o1 4.45 5.00 5.2 0.1752 0.1969 0.2047 c 4.58 5.03 5.33 0.1803 0.198 0.2098 k 12.7 0.5 o2 0.407 0.5 0.508 0.016 0.0197 0.02 a 0.35 0.0138 to92.tbl LM134-lm234-lm334 10/10
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