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st662a dc-dc converter from 5v to 12v, 0.03a for flash memory programming supply june 1997 n output voltage: 12v 5% n supply voltage range: 4.5v to 5.5v n guaranteed output current up to 30ma n very low quiescent current: 100 m a n logic controlled electronic shutdown: 1 m a n just capacitors needed (no inductor) description the st662a is a regulated charge pump dc-dc converter. it provides 12v 5% output voltage to program byte-wide flash memory, and can supply 30ma output current from input as low as 4.75v a logic controlled shut down pin that interfaces directly with microprocessor reduces the sypply current to only 1 m a typical application circuit dip-8 so-8 1/12
absolute maximum ratings symbol parameter value unit v cc dc input voltage to gnd - 0.3 to 6 v sh dn shutdown voltage -0.3 to v cc +0.3 v i o output current continuous 50 m a p tot power dissipation 500 mw t op operating ambient temperature range (for ac series ) (for ab series ) 0 to 70 - 40 to 85 o c o c t stg storage temperature range - 40 to 150 o c absolute maximum rating are those values beyond which damage to the device may occur. functional operation under these condition is not implied. connection diagram and (top view) pin connections pin no symbol name and function 1 c1- negative terminal for the first charge pump capacitor 2 c1+ positive terminal for the first charge pump capacitor 3 c2- negative terminal for the second charge pump capacitor 4 c2+ positive terminal for the second charge pump capacitor 5v cc supply voltage 6v out 12v output voltage v out = v cc when in sshutdown mode 7 gnd ground 8 shdn active high c-mos logic level shutdown input. shdn is internally pulled up to v cc . connect to gnd for normal operation. in shutdown mode the charge pumps are turned off and v out = v cc ordering numbers type dip-8 so-8 (*) st662ab st662abn st662abd st662ac st662acn st662acd (*) available in tape and reel with "-tr" suffix st662a 2/12
electrical characteristics (refer to the test circuits, v cc = 4.5v to 5.5v t a = t min to t max unless otherwise specified. typical value are referred at t a = 25 o c) symbol parameter test conditions min. typ. max. unit v o output voltage i o = 0 ma to 20 ma 11.4 12 12.6 v v o output voltage i o = 0 ma to 30 ma v cc = 4.75 to 5.5 v 11.4 12 12.6 v i q1 quiescent current no load, v shdn = 0 100 500 m a i q2 shutdown current no load, v shdn = v cc 110 m a i sh shutdown pin current v shdn = 0v, v cc = 5v v shdn = v cc = 5v -50 -12 0 -5 m a m a v il shutdown input low threshold 0.4 v v ih shutdown input high threshold 2.4 v f o oscillator frequency v cc = 5v, i o = 30 ma 400 khz n power efficecy v cc = 5v, i o = 30 ma 72 % r sw v cc - v out switch impedance v shdn = v cc = 5v, i o = 100 m a12k w do not overload or short the output to ground. if the above conditions are observerd, the dev ice may be damaged. output voltage vs temperature supply current vs temperature output voltage vs temperature supply currernt vs supply voltage st662a 3/12
output voltage vs shutdown input voltage test circuit output voltage vs shutdown input voltage shdn pin current vs temperature output voltage vs shutdown input voltage st662a 4/12
description the st662 is an ic developed to provide a 12v regulated output 30ma from voltage input as low as 4.75 without any inductors. it is useful for a wide range of applications and its performances makes it ideal for flash memory programming supply. an evaluation kit is provided to facilitate the application. this include a single-side demo board designed for surface-mount components.the operating principle of st662 (see fig. 1) is to charge c1 and c2 capacitor by closing the s1 switch (while s2 is opened) at the v cc voltage. after s1 will be opened and s2 closed so that c1 and c2 capacitors are placed in series one to each other, and both are in series with vin.the sum of vc1 and vc2 and vin is applied to the capacitor c4. this works as voltage tripler. an amplifier error checks the output voltage and blocks the oscillator if the output voltage is greater than 12v. the shutdown pin is internally pulled to v cc . when it is held low the output voltage rises to +12v. fig.2 shows the transition time of the shut down pin when the vshdn goes from 5v to 0v. input logic levels of this input are cmos compatible. applying a logic high at this input, the v out oscillator will be blocked and the v out will reach thev in value by d1. in this condition i cc will be figure 1: operating principle circuit low as 1 m a. the fig.3 shows the transition time of the shut down pin when the vshdn goes from 0v to 5v. figure 2: exiting shutdown time= 20us/div, vertical = 5v/div 5v 0v 12v 5v shdn vout figure 3: entering shutdown time= 1ms/div, vertical = 5v/div 5v 0v 12v 5v shdn vout note: v cc = 5v, i out = 200 m a note: v cc = 5v, i out = 200 m a st662a 5/12
application circuit based on fast charge/discharge of capacitors, this circuit involves high di/dt values limited only by r on of switches. this implies a critical layout design due to the need to minimize inductive paths and place capacitors as close as possible to the device. a good layout design is strongly recommended for noise reason. for best performance, use very short connections to the capacitors and the values shown in table 1. c3 and c4 must have low esr in order to minimize the output ripple. their values can be reduced to 2 m f and 1 m f, respectively, when using ceramic capacitors, but must be of 10 m f or larger if aluminium electrolytic are chosen. c5 must be placed as close to the device as possible and could be omitted if very low output noise performance are not required. fig 4 and fig 5 show, respectively, our evaluation kit layout and the relatively electrical shematic. table 1: list of components capacitor type value ( m f) charge pump c1 ceramic 0.22 charge pump c2 ceramic 0.22 input c3 electrolytic tantalum 4.7 output c4 electrolytic tantalum 4.7 decoupling c5 ceramic 0.1 figure 5: electrical schematic figure 4: kit lay-out st662a 6/12
output voltage vs output current load transient response time= 1ms/div iout 20ma/div shdn vout vout 100mv/div efficency vs output current line transient response time= 1ms/div vin 1v/div vout 200mv/div 5.5v 4.5v st662a output performance note: v cc = 5v, i out = 0 to 30ma note: v cc = 4.5 to 5.5v, i out = 30ma st662a 7/12
table 2: list of components capacitor type value ( m f) c1a ceramic 0.22 c2a ceramic 0.22 c1b ceramic 0.22 c2b ceramic 0.22 c3 electrolytic tantalum 10 c4 electrolytic tantalum 10 c5 ceramic 0.22 figure 6: application circuit for two st662a in parallel how to increase output current or output voltage capability current capability is limited by r on of internal switches. it is possible to increase it connecting in parallel two or more st662a devices; each one of them can supply 30ma. the figure 6 shows the electric schematic. the capacitors c3, c4 and c5 must be placed very close to the ics on the board. if this is not possible, you can place two different capacitors, each of them of half value, very close to the respective integrated circuit. fig. 8 show the output current capability of the proposed circuit. if an output voltage greater than 12v is required, its possible to realize the circuit of the following diagram (figure 7). the relevant output current capability is shown in figure 9 in which is shown the output voltage vs load current. st662a 8/12
figure 7: application circuit for output voltage greater than 12v figure 8: output voltage for the application with two device in parallel figure 9: output voltage for application with output voltage greater than 12v st662a 9/12
dim. mm inch min. typ. max. min. typ. max. a3.3 0.130 a1 0.7 0.028 b 1.39 1.65 0.055 0.065 b1 0.91 1.04 0.036 0.041 b0.5 0.020 b1 0.38 0.5 0.015 0.020 d9.80.386 e8.8 0.346 e2.54 0.100 e3 7.62 0.300 e4 7.62 0.300 f7.10.280 i4.80.189 l3.3 0.130 z 0.44 1.6 0.017 0.063 p001f plastic dip-8 mechanical data st662a 10/12
dim. mm inch min. typ. max. min. typ. max. a1.750.068 a1 0.1 0.25 0.003 0.009 a2 1.65 0.064 a3 0.65 0.85 0.025 0.033 b 0.35 0.48 0.013 0.018 b1 0.19 0.25 0.007 0.010 c 0.25 0.5 0.010 0.019 c1 45 (typ.) d 4.8 5.0 0.188 0.196 e 5.8 6.2 0.228 0.244 e1.27 0.050 e3 3.81 0.150 f 3.8 4.0 0.14 0.157 l 0.4 1.27 0.015 0.050 m0.60.023 s 8 (max.) 0016023 so-8 mechanical data st662a 11/12
information furnished is believed to be accurate and reliable. however, sgs-thomson microelectronics assumes no responsability for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may results from its use. no license is granted by implication or otherwise under any patent or patent rights of sgs-thomson microelectronics. specification s mentioned in this publication are subject to change without notice. this publication supersedes and replaces all information previously s upplied. sgs-thomson microelectronics products are not authorized for use as critical components in life support devices or systems with out express written approval of sgs-thomson microelectonics. ? 1997 sgs-thomson microelectronics - printed in italy - all rights reserved sgs-thomson microelectronics group of companies australia - brazil - canada - china - france - germany - hong kong - italy - japan - korea - malaysia - malta - morocco - the n etherlands - singapore - spain - sweden - switzerland - taiwan - thailand - united kingdom - u.s.a . st662a 12/12

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