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l4987 series very low drop voltage regulators with inhibit and dropout control flag october 1998 n very low dropout voltage (0.25v typ.) n dropout control flag n very low quiescent current (typ. 90 m a in off mode, 500 m a in on mode) n output current up to 200 ma n logic-controlled electronic shutdown n output voltages of 3v, 5v 8.7v 12v n internal current and thermal limit n only 2.2 m f for stability n available in 2% selection at 25 o c n supply voltage rejection: 70 db (typ.) description the l4987 is a very low drop regulator available in ppak. the very low drop-voltage (0.5v max at 200 ma) and the very low quiescent current make it particularly suitable for low noise, low power applications, and in battey powered systems. the input dump protection up to 40v makes it ideal for automotive applications. a shutdown logic control function is available (pin2, ttl compatible). this means that when the device is used as a local regulator, it is possible to put a part of the boad in standby, decreasing the total power consumption. the regulator employs an output pin (open collector) providing a logic signal when the pass transistor is in saturation at low input voltage, this signal can be used to prevent the pop-up phenomenon in the car radio. in battery powered systems (the cellular phone, notebook) it is possible to use the flag to monitor the battery charge status through the dropout of the regulator. schematic diagram ppak ? 1/11
absolute maximum ratings symbol parameter value unit v i dc input voltage 40 v i o output current internally limited ma p tot power dissipation internally limited mw t stg storage temperature range - 40 to 150 o c t op operating junction temperature range - 40 to 125 o c absolute maximum rating are those values beyond wich damage to the device may occur. functional operation under these condition s is not implied. thermal data symbol parameter dpak/ppak unit r thj-case r thj-amb thermal resistance junction-case thermal resistance junction-ambient 8 100 o c/w o c/w connection diagram (top view) ordering numbers type output voltage l4987cpt30 (*) l4987cpt50 (*) l4987cpt87 (*) l4987cpt120 (*) 3 v 5 v 8.7 v 12 v (*) available even in tape & reel l4987 series 2/11
electrical characteristics for l4987cpt30 (refer to the test circuits, v i = 6 v, i out = 5 ma, t j = 25 o c, c i = 0.1 m f, c o = 2.2 m f unless otherwise specified) symbol parameter test conditions min. typ. max. unit v o output voltage i o = 200 ma, v i = 6 v i o = 200 ma, v i = 6 v -40 3.62 v v oh = 15 v 10 m a l4987 series 3/11
electrical characteristics for l4987cpt50 (refer to the test circuits, v i = 8 v, i out = 5ma, t j = 25 o c, c i = 0.1 m f, c o = 2.2 m f unless otherwise specified) symbol parameter test conditions min. typ. max. unit v o output voltage i o = 200 ma, v i = 8 v i o = 200 ma, v i = 8 v -40 5.85 v v oh = 15 v 10 m a l4987 series 4/11
electrical characteristics for l4987cpt87 (refer to the test circuits, v i = 11.7v, i out = 5ma, t j = 25 o c, c i = 0.1 m f, c o = 2.2 m f unless otherwise specified) symbol parameter test conditions min. typ. max. unit v o output voltage i o = 200 ma, v i =11.7 v i o = 200 ma, v i =11.7 v -40 9.55 v v oh = 15 v 10 m a l4987 series 5/11
electrical characteristics for l4987cpt120 (refer to the test circuits, v i = 15v, i out = 5ma, t j = 25 o c, c i = 0.1 m f, c o = 2.2 m f unless otherwise specified) symbol parameter test conditions min. typ. max. unit v o output voltage i o = 200 ma, v i =15 v i o = 200 ma, v i =15 v -40 12.75 v v oh = 15 v 10 m a l4987 series 6/11
output and flag voltage vs input voltage output and flag voltage vs input voltage output and flag voltage vs input voltage output voltage vs input voltage output voltage vs input voltage typical performance characteristics (unless otherwise specified t j =25 o c, c in =c out =1 m f) output voltage vs input voltage l4987 series 7/11
application hint of l4987cpt30 how to use the control flag the flag produces a logic "low" whenever the output fall out out of regulation. an "out of regulation condition can result from: 1) low input voltage (v in v out + v drop ) 2) curent limiting 3) thermal limiting figure 1 to 2 show the typical behaviour of the output voltage and the control flag versus the input voltage and the temperatre. no hysteresis is implemented; so the response of v out and v flag are the same either when the v in ramps up or down. the control flag is an open collector which requires an external pull-up resistor. this may be connected to the regulator output (figure 3) or some other supply voltage (figure 4). using the regulator output prevents an invalid "high" on the flag which occurs if it is pulled up to an external voltage while the regulator input voltage is reduced below about 2v (figue 5). concerning the pull-up resistor its value must be properly chosen as suggested below. when "low" as it is possible to see in figure 6 the control flag voltage is: v flag(low) = v ce = 0.5 = v supply - r pull x i fl v supply is chosen by design and, thus is known, while i fl must be at maximum 10ma. then 0.5v 3 v supply - r pull x 10ma the minimum value of r pull , is, so, determined by the following equation: r pull(min) 3 v supply - 0.5 10 ma regarding the maximum value of r pull note that its value depends of the type of logic used (cmos, ttl etc.), the transistor leackage current and the presence or not of a load on v flag . the following example shows how to determine the r pull max in the case of cmos logic, no load and 10 m a (for l4978 it is the maximum value of i fh ) of control flag leakage current. becaause of cmos logic: v flag(high) 3 2 3 v supply but: v flag(high) = v supply - r pull x i fh 3 2 3 v supply so, the maximum value is determined by the following equation: r pull(max) 1 3 v supply 10 a figure 1: output and flag voltage vs input figure 2: flag voltage vs input l4987 series 8/11
figure 3: test circuit figure 4: test circuit figure 5: output and flag voltage vs input figure 6: equivalent output circuit l4987 series 9/11
dim. mm inch min. typ. max. min. typ. max. a 2.2 2.4 0.086 0.094 a1 0.9 1.1 0.035 0.043 a2 0.03 0.23 0.001 0.009 b 0.4 0.6 0.015 0.023 b2 5.2 5.4 0.204 0.212 c 0.45 0.6 0.017 0.023 c2 0.48 0.6 0.019 0.023 d 6 6.2 0.236 0.244 e 6.4 6.6 0.252 0.260 g 4.9 5.25 0.193 0.206 g1 2.38 2.7 0.093 0.106 h 9.35 10.1 0.368 0.397 l2 0.8 1 0.031 0.039 l4 0.6 1 0.023 0.039 0078180/b ppak mechanical data l4987 series 10/11
information furnished is believed to be accurate and reliable. however, stmicroelectronics assumes no responsib ility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of stmicroelectroni cs. specifi cation mentio ned in this publication are subject to change without notice. this publication supersedes and replaces all in formation previou sly supplied. stmicroe lectron ics products are not authorized for use as critical components in life support devices or systems without express written approval of stmicroelectron ics. the st logo is a registered trademark of stmicroelectronics ? 1998 stmicroelectronics C pr inted in italy C all rights reserved stmicroelectronics group of companies australia - brazil - canada - china - france - germany - italy - japan - korea - malaysia - malta - mexico - morocco - the neth erlands - singapore - spain - sweden - switzerland - t aiwan - thailand - united kingdom - u.s.a. http://www.st.com . l4987 series 11/11

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