regulating pulse width modulator features 8v to 35v operation 5.1v reference trimmed to 1% 100hz to 500khz oscillator range separate oscillator sync terminal adjustable deadtime control internal soft-start input undervoltage lockout latching p.w.m. to prevent multiple pulses dual source/sink output drivers high reliability features - sg1525a, sg1527a available to mil-std-883b mil-m38510/12602bea - JAN1525AJ mil-m38510/12604bea - jan1527aj radiation data available lmi level "s" processing available description the sg1525a/1527a series of pulse width modulator integrated circuits are designed to offer improved performance and lower external parts count when used to implement all types of switching power supplies. the on-chip +5.1 volt reference is trimmed to 1% initial accuracy and the input common-mode range of the error amplifier includes the reference voltage, eliminating external potentiometers and divider resistors. a sync input to the oscillator allows multiple units to be slaved together, or a single unit to be synchronized to an external system clock. a single resistor between the c t pin and the discharge pin provides a wide range of deadtime adjustment. these devices also feature built-in soft-start circuitry with only a timing capacitor required externally. a shutdown pin controls both the soft-start circuitry and the output stages, providing instantaneous turn-off with soft-start recycle for slow turn-on. these functions are also controlled by an undervoltage lockout which keeps the outputs off and the soft-start capacitor discharged for input voltages less than that required for normal operation. another unique feature of these pwm circuits is a latch following the comparator. once a pwm pulse has been terminated for any reason, the outputs will remain off for the duration of the period. the latch is reset with each clock pulse. the output stages are totem-pole designs capable of sourcing or sinking in excess of 200ma. the sg1525a output stage features nor logic, giving a low output for an off state. the sg1527a utilizes or logic which results in a high output level when off. block diagram sg1525a/sg2525a/sg3525a sg1527a/sg2527a/sg3527a 11/91 rev 1.4 10/02 l infinity microelectronics inc. copyright ? 1996 11861 western avenue garden grove, ca 92841 1 (714) 898-8121 fax: (714) 893-2570
sg1525a/sg1527a series 11/91 rev 1.4 10/02 l infinity microelectronics inc. copyright ? 1996 11861 western avenue garden grove, ca 92841 2 (714) 898-8121 fax: (714) 893-2570 oscillator charging current ............................................ operating junction temperature range hermetic (j, l packages) ..................................... plastic (n, dw packages ) ....................................... storage temperature range .......................... lead temperature (soldering, 10 seconds) ................. supply voltage (+v in ) ....................................................... collector supply voltage (v c ) ........................................... logic inputs ....................................................... analog inputs ....................................................... output current, source or sink ................................... reference load current ............................................... 40v 40v -0.3v to 5.5v -0.3v to v in 500ma 50ma 5ma 150 c 150 c -65 c to 150 c 300 c absolute maximum ratings (note 1) note 1. values beyond which damage may occur. input voltage (+v in ) ................................................ collector voltage (v c ) .......................................... sink/source load current (steady state) ............. sink/source load current (peak) ......................... reference load current ........................................ oscillator frequency range ....................... oscillator timing resistor (r t ) ........................ 8v to 35v 4.5v to 35v 0 to 100ma 0 to 400ma 0 to 20ma 100hz to 350khz 2k w to 150k w deadtime resistor range (r d ) ............................. maximum shutdown source impedance ......................... oscillator timing capacitor (c t ) ................... operating ambient temperature range sg1525a/sg1527a .................................... sg2525a/sg2527a ...................................... sg3525a/sg3527a ......................................... 0 w to 500 w 5k w 0.001 m f to 0.1 m f -55 c to 125 c -25 c to 85 c 0 c to 70 c note 2: range over which the device is functional. recommended operating conditions (note 2) electrical characteristics (unless otherwise specified, these specifications apply over the operating ambient temperatures for sg1525a/sg1527a with -55 c t a 125 c, sg2525a/sg2527a with -25 c t a 85 c, sg3525a/sg3527a with 0 c t a 70 c, and +v in = 20v. low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient temperature.) 5.05 5.00 reference section t j = 25 c v in = 8v to 35v i l = 0 to 20ma over operating temperature range over line, load and temperature v ref = 0v, t j = 25 c 10hz f 10khz, t j = 25 c t j = 125 c output voltage line regulation load regulation temperature stability (note 3) total output voltage range (note 3) short circuit current output noise voltage (note 3) long term stability (note 3) min. typ. max. min. typ. max. note 3. these parameters, although guaranteed over the recommended operating conditions, are not 100% tested in production. note 4. f osc = 40khz (r t = 3.6k w , c t = 0.01 m f, r d = 0 w ) note 5. applies to sg1525a/2525a/3525a only, due to polarity of output pulses. sg3525a sg3527a sg1525a/2525a sg1527a/2527a units test conditions parameter v mv mv mv v ma m vrms mv/khr 5.20 30 50 50 5.25 100 200 50 5.10 10 20 20 80 40 20 5.00 4.95 5.15 30 50 50 5.20 100 200 50 5.10 10 20 20 80 40 20 thermal data j package: thermal resistance- junction to case , q jc .................. 30c/w thermal resistance- junction to ambient , q ja .............. 80c/w dw package: thermal resistance- junction to case , q jc .................. 40c/w thermal resistance- junction to ambient , q ja ............. 95c/w l package: thermal resistance- junction to case , q jc .................. 35c/w thermal resistance- junction to ambient , q ja ........... 120c/w n package: thermal resistance- junction to case , q jc ................... 40c/w thermal resistance- junction to ambient , q ja ............. 65c/w note a. junction temperature calculation: t j = t a + (p d x q ja ). note b. the above numbers for q jc are maximums for the limiting thermal resistance of the package in a standard mount- ing configuration. the q ja numbers are meant to be guidelines for the thermal performance of the device/pc- board system. all of the above assume no ambient airflow.
sg1525a/sg1527a series 11/91 rev 1.4 10/02 l infinity microelectronics inc. copyright ? 1996 11861 western avenue garden grove, ca 92841 3 (714) 898-8121 fax: (714) 893-2570 18 17 6 output drivers section (each transistor, v c = 20v) i source = 20ma i source = 100ma i sink = 20ma i sink = 100ma v comp and v ss = high v c = 35v c l = 1nf, t j = 25 c c l = 1nf, t j = 25 c v sd = 3v, c s = 0, t j = 25 c output high level output low level undervoltage lockout collector leakage (note 5) rise time fall time shutdown delay (note 3) 50 0.4 0.4 25 soft-start section v shutdown = 0v v shutdown = 2v v shutdown = 2.5v soft start current soft start voltage shutdown input current m a v ma p.w.m. comparator section (note 4) v comp = 0.6v v comp = 3.6v zero duty cycle maximum duty cycle minimum duty cycle maximum duty cycle input threshold (note 4) input bias current % % v v m a 0.4 2.2 8 200 600 300 0.5 19 18 0.2 1.0 7 100 50 0.2 37.6 350 1.7 3.0 0.3 1.2 oscillator section (note 4) t j = 25 c v in = 8v to 35v min t j max r t = 150k w , c t = 0.1 m f r t = 2k w , c t = 1nf i rt = 2ma t j = 25 c sync voltage = 3.5v initial accuracy voltage stability temperature stability (note 3) minimum frequency (note 3) maximum frequency (note 3) current mirror clock amplitude clock width sync threshold sync input current min. typ. max. min. typ. max. sg3525a sg3527a sg1525a/2525a sg1527a/2527a units test conditions parameter electrical characteristics (continued) khz % % hz khz ma v m s v ma 42.4 2 6 150 2.2 1.0 2.8 2.5 40 1 3 2.0 3.5 0.5 2.0 1.0 37.6 350 1.7 3.0 0.3 1.2 42.4 1 6 150 2.2 1.0 2.8 2.5 40 0.3 3 2.0 3.5 0.5 2.0 1.0 error amplifier section (v cm = 5.1v) input offset voltage input bias current input offset current dc open loop gain gain-bandwidth product (note 3) output low level output high level common mode rejection supply voltage rejection r l 3 10m w, t j = 25 c a v = 0db, t j = 25 c v cm = 1.5v to 5.2v v in = 8v to 35v 60 1 3.8 60 50 0.5 1 75 2 0.2 5.6 75 60 5 10 1 0.5 60 1 3.8 60 50 2 1 75 2 0.2 5.6 75 60 10 10 1 0.5 mv m a m a db mhz v v db db 45 0.6 0 3.6 2.0 49 0.9 3.3 .05 45 0.6 0 3.6 2.0 49 0.9 3.3 .05 80 0.6 1.0 25 50 0.4 0.4 80 0.6 1.0 19 18 0.2 1.0 7 100 50 0.2 18 17 6 0.4 2.2 8 200 600 300 0.5 v v v v v m a ns ns m s total standby current standby current v in = 35v ma 20 14 20 14
sg1525a/sg1527a series 11/91 rev 1.4 10/02 l infinity microelectronics inc. copyright ? 1996 11861 western avenue garden grove, ca 92841 4 (714) 898-8121 fax: (714) 893-2570 figure 1 - oscillator schematic error amplifier section figure 3 - oscillator discharge time vs. r d and c t figure 2 - oscillator charge time vs. r t and c t figure 5 - error amplifier open-loop frequency response figure 4 - error amplifier oscillator section
sg1525a/sg1527a series 11/91 rev 1.4 10/02 l infinity microelectronics inc. copyright ? 1996 11861 western avenue garden grove, ca 92841 5 (714) 898-8121 fax: (714) 893-2570 figure 7 - output saturation characteristics figure 6 -output circuit (? circuit shown) application information low power transformers can be driven directly by the sg1525a. automatic reset occurs during deadtime, when both ends of the primary winding are switched to ground. the low source impedance of the output drivers provides rapid charging of power fet input capacitance while minimizing exter- nal components. for single-ended supplies, the driver outputs are grounded. the v c terminal is switched to ground by the totem-pole source transistors on alternate oscillator cycles. in conventional push-pull bipolar designs, forward base drive is controlled by r 1 - r 3 . rapid turn-off times for the power devices are achieved with speed-up capacitors c 1 and c 2 . output section
sg1525a/sg1527a series 11/91 rev 1.4 10/02 l infinity microelectronics inc. copyright ? 1996 11861 western avenue garden grove, ca 92841 6 (714) 898-8121 fax: (714) 893-2570 application information (continued) shutdown options 1. use an external transistor or open-collector comparator to pull down on the comp terminal. this will set the pwm latch turning off both outputs. if the shutdown signal is momentary, pulse- by-pulse protection can be accomplished as the pwm latch will be reset with each clock pulse. 2. the same results can be accomplished by pulling down on the soft-start terminal with the difference that on this pin, shutdown will not affect the amplifier compensation network but must discharge any soft-start capacitor. 3. apply a positive-going signal to the shutdown terminal. this will provide most rapid shutdown of the outputs but will not immediately set the pwm latch if there is a soft-start capacitor. this capacitor will discharge but with a current of approxi- mately twice the charging current. 4. the shutdown terminal can be used to set the pwm latch on a pulse-by-pulse basis if there is no external capacitance on soft-start terminal. slow turn-on may still be accomplished by applying an external capacitor, blocking diode, and charging resistor to the comp terminal. (see sg1524 application note). sg1525a/1527a lab test fixture
sg1525a/sg1527a series 11/91 rev 1.4 10/02 l infinity microelectronics inc. copyright ? 1996 11861 western avenue garden grove, ca 92841 7 (714) 898-8121 fax: (714) 893-2570 note 1. contact factory for jan and desc product availablity. 2. all packages are viewed from the top. connection diagrams & ordering information (see notes below) 16-pin ceramic dip j - package ambient temperature range sg1525aj/883b -55 c to 125 c JAN1525AJ -55 c to 125 c sg1525aj/desc -55 c to 125 c sg1525aj -55 c to 125 c sg2525aj -25 c to 85 c sg3525aj 0 c to 70 c sg1527aj/883b -55 c to 125 c jan1527aj -55 c to 125 c sg1527aj/desc -55 c to 125 c sg1527aj -55 c to 125 c sg2527aj -25 c to 85 c sg3527aj 0 c to 70 c part no. package connection diagram v ref +v in output b v c ground output a shutdown compensation soft-start n.i. input inv. input r t 2 3 4 5 6 7 8 1 15 16 14 13 10 9 12 11 c t discharge sync osc. output sg2525an -25 c to 85 c sg3525an 0 c to 70 c sg2527an -25 c to 85 c sg3527an 0 c to 70 c 16-pin plastic dip n - package 2 3 4 5 6 7 8 v ref +v in shutdown compensation n.i. input inv. input r t 15 16 14 13 10 9 12 11 1 soft-start output b v c ground output a c t discharge sync osc. output 20-pin ceramic leadless chip carrier l- package 4 5 6 7 8 321 9 111213 10 14 15 16 17 18 20 19 11. n.c. 12. comp. 13. shutdown 14. output a 15. ground 16. n.c. 17. v c 18. output b 19. +v in 20. v ref 1. n.c. 2. inv. input 3. n.i. input 4. sync 5. osc. output 6. n.c. 7. c t 8. r t 9. discharge 10. soft-start sg1525al/883b -55 c to 125 c sg1525al -55 c to 125 c sg1527al/883b -55 c to 125 c sg1527al -55 c to 125 c 16-pin wide body plastic s.o.i.c. dw - package sg2525adw -25 c to 85 c sg3525adw 0 c to 70 c sg2527adw -25 c to 85 c sg3527adw 0 c to 70 c
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