3.3 - 33 3.3 4 11 r0 1.0 amp, 5v, 12v, 15v and adjustable output voltage versions in mo-078 metal package step-down switching voltage regulator in hermetic isolated package features ? similar to industry standard lm1575 ? available in 5v, 12v, 15v, and adjustable versions ? 1.0 amp output ? wide input voltage range, 4v to 60v ? 53 khz fixed frequency internal oscillator ? high efficiency ? hermetic metal packages description this series of regulators are monolithic integrated circuits designed for the active functions of a step down, buck or buck/boost regulator. it requires only four readily available standard components to complete the dc to dc converter design at 1 amp. current limiting and thermal shutdown features fully protect the device against overstress. the hermetic package is ideally suited for those critical environments requiring high reliability over a wide operating temperature range. absolute maximum ratings @ t c = 25c maximum supply voltage om1575 .............................................................45 v omh1575 ...........................................................63 v on/off pin input voltage ...................................... -0.3 v v v in output voltage to ground (steady state) ..................................-1 v power dissipation ............................................ internally limited operating temperature range ................................ -55c to + 150c storage temperature range .................................. -65c to + 150c thermal resistance, r q jc ............................................ 2.4c/w lead soldering temperature (10 seconds) ................................ 260c block diagram om1575 series omh1575 series + - + - drv pwm e/a ref reg on/off osc reset protection gnd output on/off input feedback internal resistors for fixed options only
3.3 - 34 3.3 om1575 omh1575 series electrical characteristics unless otherwise specified v in = 12v for 5v and adj options; 25v for 12v; and 30v for 15v models; v out = 5v for adj, i o = 0.2a to 1a, t j = 25c. v in rated = 40v, and 60v for omh series. test conditions limits parameter symbol v in i o t j min. typ. max. unit om1575-05 v o 0.2a 4.95 5.05 8v to v in rated over temp. 4.80 5.20 v 4.85 5.15 om1575-12 v o 0.2a 11.88 12.12 15v to v in rated over temp. 11.52 12.48 v 11.64 12.36 om1575-15 v o 0.2a 14.85 15.15 18v to v in rated over temp. 14.40 15.60 v 14.55 15.45 feedback voltage v fb 0.2a 1.217 1.243 v out = 5v 8v to v in rated over temp. 1.193 1.267 v om1575-a 1.205 1.255 feedback bias current i b 12v 0.2a 50 100 na over temp. 500 efficiency/option n 51a82 12 15v 88 % 15 18v 90 a v o = 5v 12v 82 switching frequency f sx 47 52 58 khz over temp. 43 62 saturation voltage (1) v sat 1a over temp. 0.9 1.2 v 1.4 maximum duty cycle (on) (3) dc 93 98 % current limit (1) peak current 1.7 2.2 3.0 a peak current i cl t on 3sec over temp. 1.3 3.2 output leakage current (2) output = 0v i l v in rated 2 ma output = -1v 7.5 30 quiescent current (2) i o 510 ma over temp. 12 standby quiescent i stby 50 200 a current (on/off pin = 5v) over temp. 500 on/off pin logic v ih input level 2.2 v v out = 0v over temp. 2.4 1.4 v out = option v il 1.0 v over temp. 1.2 0.8 on/off input current on/off = 5v (off) i ih 0.2a 12 30 a on/off = 5v (off) i il 010 notes: over temperature: -55c to 150c. (1) output sourcing current - resistive load, no inductor or capacitor. (2) feedback = v o +1.0v. (3) feedback = 0v. (4) not all parameters are 100% tested during production. consult the factory for more information.
3.3 - 35 3.3 om1575 omh1575 series operational data dropout voltage minimum operating voltage 2.5 2.0 1.5 1.0 0.5 0 -75 -50 -25 0 25 50 75 100 125 150 v in - v out (v) junction temperature (?) 5.0 4.0 3.0 2.0 1.0 0 -75 -50 -25 0 25 50 75 100 125 150 input voltage (v) junction temperature (?) line regulation (adjustable version only) feedback pin current 15 10 5 0 -5 -10 0 10203040 60 normalized feedback voltage (mv) input voltage (v) 50 20 75 25 0 -25 -50 -75 -75 -50 -25 0 25 50 75 100 125 150 feedback current (na) junction temperature (?) normalized feedback voltage (adjustable version only) feedback voltage vs duty cycle (adjustable version only) 15 5 0 -5 -15 -25 -75 -50 -25 0 25 50 75 100 125 150 normalized feedback voltage (mv) junction temperature (?) 10 25 15 5 0 -5 -10 -15 0 20406080100 feedback voltage change (mv) duty cycle (%) i o = 200ma i o = 200ma v in = 40v v in = 7v v in = 12v i o = 200ma normalized to t j = 25? normalized to v in = 10v i o = 200ma, v out = 5v t j = 25? i o = 1a i o = 200ma v out = 1.23v d v out = 5% r ind = 0.2 w
3.3 - 36 3.3 operational data om1575 omh1575 series supply current vs. duty cycle 20 15 10 5 20 40 60 80 100 supply current (ma) duty cycle (%) supply current (ma) input voltage (v) current limit switch saturation voltage 2.0 1.0 0 output current (a) junction temperature (?) 1.2 3.0 1.0 0.8 0.6 0.4 0.2 0.2 0.4 0.6 0.8 1.0 -75 -50 -25 0 25 50 75 100 125 150 -75 -50 -25 0 25 50 75 100 125 150 saturation voltage (v) switch current (a) efficiency 90 85 80 75 70 65 0 10203040 60 efficiency (%) input voltage (v) 95 standby quiescent current ( m a) junction temperature (?) i o = 200ma v in = 7v v in = 40v supply current 18 20 16 14 12 10 8 6 10 0 20304060 i load = 1a i load = 200ma measured at ground pin t j = 25?, v out = 5v standby quiescent current 200 150 100 50 v in = 40v v out = 12v v out = 3v 1a 1a 200ma 200ma v in = 12v v in = 25v t j = -55? t j = 25? t j = 150? v on/off = 5v
3.3 - 37 3.3 om1575 omh1575 series catch diode if the output must be capable of a sustained short, the i f rating must be above 3a. the use of an ultra fast diode with soft recovery characteristics or a schottky will be adequate. the major impact on schottky versus an ultra fast is efficiency. schottkys will provide approximately 4% to 5% improvement for output voltage below 12v, whereas above 12v the difference will become less significant. breakdown rating must be in excess of v in for margin. input capacitor the value shown will be adequate for most applications. ripple voltage at the switching frequency is caused by the input capacitor supplying load current during the on time of the power switch. the use of a low esr switching type capacitor will minimize ripple to an acceptable level. layout use short connections with a central point ground to prevent improper operation caused by stray inductance and ground loops. output capacitor ripple voltage on v out is directly related to the value of c out and the internal resistance esr of c out . output noise can be lowered by increasing c out or by selecting a capacitor with a lower esr. esr must be approximately 0.07 or above to maintain stability, otherwise raise value of c out . the above fixed and adjustable voltage selections will be adequate for most applications for output currents from 150ma to 1.0a. applications of v out below 5v or above 24v may require component adjustment for maximum performance; please contact factory for application assistance. + + + - + - drv pwm e/a ref rec on/ off osc reset protection c in 68 m f c out 330 m f 330 m h 53 1 4 2 d1 3a l1 buck mode fixed voltage + + + - + - drv pwm e/a ref rec on/ off osc reset protection c in 68 m f c out 330 m f 330 m h 53 1 4 2 d1 3a l1 r2 r1 2k buck mode adjustable voltage
3.3 - 38 3.3 om1575 omh1575 series v in c out output + regulated output c in 2 4 feedback 3 5 1 1n914 10k 0.47 m f to 3.0 m f 2.2k spike filter reduces input noise, causing false triggering of delay. turn-on delay with spike filter c in v out c out +v in 10 m f+ tant 1 m h+ gnd 35 dc input on/off output l1 switching spike reduction typical application switching spikes switching spikes will also occur due to distributive capacitance across turns of the inductor when combined with output capacitor series inductance (esl). reduction to a level at or below the switching ripple can be achieved by using a post filter, as shown in the switching spike reduction schematic.
3.3 - 39 3.3 om1575 omh1575 series +v in c in c out output l1 feedback + unregulated dc input + regulated output + 2 4 3 5 1 + d1 gnd on/off +5v 0 off on shutdown input ttl, cmos, etc. +v in c in c out output l1 feedback + unregulated dc input + regulated output + 2 4 3 5 1 + d1 gnd on/off +5v 0 off on shutdown input 100k 100k 100k +v in c out output + regulated output c in 2 3 5 1 1n914 circuit allows for c in to be fully charged before start-up, provides c in to supply hi-peak current instead of input supply. 10k 0.47 m f to 3.0 m f typical applications typical buck shutdown turn-on delay
3.3 - 40 3.3 om1575 omh1575 series +v in c in c out output l1 feedback + unregulated dc input - regulated output + 2 4 3 5 1 + d1 gnd on/off +5v 0 off on shutdown input 100k 470k +5v 220v +v in c in c out output l1 feedback + unregulated dc input - regulated output + 2 4 3 5 1 + d1 gnd on/off +5v 0 off on shutdown input 330k 470k 470k 220k 470k inverting buck/boost shutdown +v in c out output feedback unregulated dc input + regulated output 2 4 3 5 1 gnd on/off 20k 10k r2 z1 r1 20k + q1 regulator will be off until a v in set point is reached. v o(on) @ v z + 3v be q1 under voltage lockout typical applications
3.3 - 41 3.3 om1575 omh1575 series + + - + - drv pwm e/a ref rec on/ off osc reset protection c in +5v to -5v @ 250ma 47 m f + c out 330 m f 100 m h 53 1 4 2 d1 3a l1 +5v -5v @ 250ma + + - + - drv pwm e/a ref rec on/ off osc reset protection c in +12v to -5v @ 100ma 47 m f + c out 200 m f 47 m h 53 1 4 2 d1 3a l1 +12v common -5v @ 100ma inverting buck/boost typical applications inverting buck/boost operation is a different topology of operation than buck. this difference reduces the output current capability of the device, in that the inductor must supply all of the load current during the time the power switch is off: maximum output current is approximately: i out @ 1.3/2 (1 + v o / v in ) component requirement stress is very similar to the buck with a few exceptions: ? catch diode breakdown v br must be greater than v in + v out ? input capacitor is larger due to the increased peak current during switch turn on. power dissipation of the om1575 is approximately: p d @ [ v o / ( v o + v in )] i o (1 + v o / v in ) please contact factory for additional assistance when using the buck/boost topology.
3.3 205 craw ford street, leominster, ma 01453 usa (508) 534-5776 fax (508) 537-4246 om1575 omh1575 series pin 1: v in pin 2: out pin 3: gnd pin 4: feedback pin 5: on/off 12345 mechanical outline pin connection mo-078 package z-tab package ordering information .035 .025 .270 max. .035 .005 .045 .695 .685 .250 typ . . 125 typ . .250 typ . .100 typ . .750 .500 .285 .550 .530 .125 ? 2 plcs .100 typ. .140 typ. .035 .025 .707 .697 .750 .500 .835 .815 .695 .685 .165 .155 .550 .530 .270 .240 .045 .035 .092 max. .005 pin 1: v in pin 2: out pin 3: gnd pin 4: feedback pin 5: on/off 12345 example: p/n om 1575 - 05 scm = 5 volt, c5 package with screening part voltage case number level style screening om1575 05 = 5 volt sc = mo-078 add m omh1575 12 = 12 volt scz = z-tab for 883 15 = 15 volt both packages screening a = adjustable are isolated see section 3.2
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