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www.addmtek.com copyright ? 2006 addtek corp. 1 dd019_f -- october 2006 amc3842b/43b/44b/45b c urrent m ode pwm c ontroller description features the amc3842b/43b/44b/45b are fixed frequency current-mode pwm controllers specially designed for off-line switching power supply and dc-to-dc converters with a minimum number of external components. these devices feature a trimmed oscillator for precise duty cycle control, a temperature compensate d reference, high gain error amplifier, current sensing comparator, and high current totem pole output which is suitable for driving mosfets. the under voltage lock-out (u.v.l.o.) is designed to operated with 200 a start-up current in typical, allowing an efficient bootstrap supply voltage design. the u.v.l.o. thresholds for the amc3842b/44b are 16v (on) and 10v (off), which are ideal for off-line applications. the corresponding typical threshold for the amc3843/45bb is 8.4v (on) and 7.6v (off). the amc3842b/43b can operate within 100% duty cycle and the amc3844b/45b can operate within 50% duty cycle. ? low start-up current (max. 200 a) ? optimized for off-line and dc-to-dc converters ? maximum duty cycle ? u.v.l.o. with hysteresis ? operating frequency up to 500khz ? internal trimmed bandgap reference ? high current totem pole output ? error amplifier with low output resistance ? available in 8-pin plastic dip and surface mount 14-pin s.o.i.c. ? identical pin assignment to earlier uc384x series. applications package pin out ? off-line flyback or forward converters. ? dc-to-dc buck or boost converter. ? monitor power supply 8-pin plastic dip (top view) available options device start-up voltage hysteresis max. duty cycle amc3842b 16v 6v < 100% AMC3843B 8.4v 0.8v < 100% amc3844b 16v 6v < 50% amc3845b 8.4v 0.8v < 50% 14-pin plastic s.o.i.c. surface mount (top view) 8-pin plastic s.o.i.c. surface mount (top view) order information plastic dip-8 plastic so-14 plastic so-8 t a ( o c) m 8-pin d 14-pin dm 8-pin 0 to 70 amc384xbm amc384xbd amc384xbdm 0 to 70 amc384xbm (lead free) amc384xbd (lead free) amc384xbdm (lead free) note: 1. all surface-mount packages are av ailable in tape & reel. append the letter ?t? to part number (i.e. amc384xbdt, or amc384xbdmt). 2. the letter ?f? is marked for lead free process. comp v f b i sense v ref gnd output v cc r t / c t nc nc r t / c t i sense v fb v ref v cc v c output gnd pwr nc nc comp comp v f b i sense v ref gnd output v cc r t /c t
amc3842b/43b/44b/45b copyright ? 2006 addtek corp. 2 dd019_f -- october 2006 absolute maximum ratings (note 1) supply voltage, v cc 35v output current, i o 1a analog inputs, v i -0.3v to 6.3v error amp output sink current, i sink(ea) 10ma power dissipation (t a = 25 o c), p d 1w maximum juncture temperature, t j 150 o c storage temperature range -65 o c to 150 o c lead temperature (soldiering, 10 seconds) 260 o c note 1: exceeding these ratings could cause damage to the devi ce. all voltages are with resp ect to ground. currents are posi tive into, negative out of the specified terminal. thermal data m package : thermal resistance-junction to ambient, ja 95 o c/w d package : thermal resistance-junction to ambient, ja 120 o c/w dm package : thermal resistance-junction to ambient, ja 165 o c/w junction temperature calculation: t j = t a + (p d ja ). the ja numbers are guidelines for the thermal performance of the device/pc-board system. all of the above assume no ambient airflow.
amc3842b/43b/44b/45b copyright ? 2006 addtek corp. 3 dd019_f -- october 2006 block diagram ( ) are 14 pin s.o.i.c. pin number note 2: v cc and pwr v c are internally connect ed for 8 pin packages. note 3: pwr gnd and gnd are internal ly connected for 8 pin packages. note 4: u.v.l.o. is 16v for 3842b/44b and 8.4v for 3843b/45b. note 5: hysteresis is 6v for 3842b/44b and 0.8v for 3843b/45b. note 6: toggle flip flop used only in 3844b/45b v ref internal bias 36v 2r en 5v v ref u.v.l.o. v ref good logic error amp current sense oscillator r 1 v r s pwm latch v fb current sense r t /c t pwr gnd output pwr v c gnd v cc comp t 1 ( 1 ) 2 ( 3 ) 3 ( 5 ) 4 ( 7 ) 8 ( 14 ) 5 ( 8 ) 6 ( 10 ) 7 ( 11 ) 5 ( 9 ) 7 ( 12 )
amc3842b/43b/44b/45b copyright ? 2006 addtek corp. 4 dd019_f -- october 2006 recommended operating conditions recommended operating conditions parameter symbol min. typ. max. units supply voltage v cc / v c 30 v v i ,r t /c t input voltage v i ,i sense /v fb 0 5.5 v output voltage v o , output 0 30 v supply current i cc 25 ma average output current i o 200 ma reference output current i o(ref) -20 ma timing capacitor c t 1 nf oscillator frequency f osc 100 500 khz operating free-air temperature t a 0 70 o c electrical char acteristics unless otherwise specified, these specifications apply over the operating ambient temp erature for amc384xb with 0 o c t a 70 o c; v cc = 15v(note 7); r t = 10k;c t = 3.3nf. low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient temperature. amc384xb parameter symbol test conditions min. typ. max. units reference section reference output voltage v ref t j = 25 o c, i ref = 1ma 4.9 5.0 5.1 v line regulation 12v v cc 25v,t j = 25 o c 6 20 mv load regulation 1ma i ref 20ma 6 25 mv short ciruit output current i sc t j = 25 o c -30 -100 -180 ma oscillator section oscillation frequency f t j = 25 o c 47 52 57 khz frequency change with voltage 12v v cc 25v 0.2 1.0 % frequency change with temperature (note 8) t min t a t max 5 % peak-to-peak amplitude at r t /c t v osc 1.7 v current sense section gain (note 9 & 10) a vol 2.85 3.00 3.15 v/v maximum input signal (note 9) v i(max) comp = 5v 0.9 1.0 1.1 v power supply rejection ratio (note 9) psrr 12v v cc 25v (note 9) 70 db input bias current i bias -3.0 -10 a
amc3842b/43b/44b/45b copyright ? 2006 addtek corp. 5 dd019_f -- october 2006 electrical characteri stics (continued) error amplifier section input bias current i bias -0.1 -2 a input voltage v i(ea) comp = 2.5v 2.42 2.50 2.58 v open loop voltage gain g vo 2v v o 4v 65 90 db unity gain bandwidth (note 8) ugbw t j = 25 o c 0.7 1 mhz power supply rejection ratio psrr 12v v cc 25v 60 70 db output sink current i sink v fb = 2.7v, comp = 1.1v 2 7 ma output source current i source v fb = 2.3v, comp = 5.0v -0.5 -1.0 ma high output voltage v oh v fb = 2.3v, r l = 15k ? to gnd 5 6 v low output voltage v ol v fb = 2.7v, rl = 15k ? to v ref 0.7 1.1 v output section i sink = 20ma 0.1 0.4 output low level v ol i sink = 200ma 1.4 2.2 v i source = 20ma 13 13.5 output high level v oh i source = 200ma 12 13.0 v rise time (note 9) t r t j = 25 o c, c l = 1nf 50 150 ns fall time (note 9) t f t j = 25 o c, c l = 1nf 50 150 ns under-voltage lockout section amc3842b/44b 14.5 16.0 17.5 start threshold v th(st) AMC3843B/45b 7.8 8.4 9.0 v amc3842b/44b 8.5 10 11.5 min. operating voltage AMC3843B/45b 7.0 7.6 8.2 v pwm section amc3842b/43b 94 97 100 maximum duty cycle dmax amc3844b/45b 47 48 50 % total standby current amc3842b/44b 0.2 startup current AMC3843B/45b 0.2 ma operating supply current i cc v fb = i sense = 0v 14 17 ma zener voltage v z i cc = 25ma 30 35 v note 7: adjust v cc above the start threshold before setting at 15v note 8: these parameters, although guaranteed, are not 100% tested in production prior to shipment note 9: parameters are measured at trip point of latch with v fb = 2v note 10: gain is measured between i sense and comp with the input changing from 0v to 0.8v
amc3842b/43b/44b/45b copyright ? 2006 addtek corp. 6 dd019_f -- october 2006 characterization curves below characterization curves was referenced by fig.4 oscillator discharge current vs. temperature 7 7.5 8 8.5 9 -50 -25 0 25 50 75 100 125 maximum output duty cycle vs. timing resistor 40 50 60 70 80 90 100 012345678 error amp open-loop gain and phase vs. frequency -20 0 20 40 60 80 100 current sense input threshold vs. error amp output voltage. 0 0.2 0.4 0.6 0.8 1 1.2 012345678 reference voltage change vs. source current. 0 10 20 30 40 50 60 020406080100120 reference short circuit current vs. temperature. 50 60 70 80 90 100 110 -50 -25 0 25 50 75 100 125 150 vcc=15v v osc=2v idischg (ma) dmax (%) idischg=7.5m a idischg=8.8ma vcc=15v ct=3.3mf t a =25 oc gain phase vcc=15v vo=2v to 4v rl=100k (db) 10 100 1k 10k 100k 1m f(hz) ? 30 60 90 120 150 180 v cc=15v vth (v) t a =125 oc t a =-40 oc t a =25 oc vo(v) iref ( ma ) vcc=15v ta=125 oc ta=-40oc ta=25oc vcc=15v rl 0.1 ? isc (ma) ta ( oc ) ta( oc ) ( ) ? k r t
amc3842b/43b/44b/45b copyright ? 2006 addtek corp. 7 dd019_f -- october 2006 application information fig. 1. current sense circuit peak current (i s ) is set by: i s(max) = 1v/r s fig. 3. oscillator section 1.72 fig. 2. error amplifier configuration - the amplifier can source or sink up to 0.5ma for r t < 5k, f = r t c t fig. 4. open-loop laboratory test fixture: careful grounding techniques are ne cessary for high peak currents associated with capacitive loads. timing and bypass capacitors should be connected to gnd pin in a single point ground. the transistor and 5k potentiometer are us ed to sample the oscillat or waveform and apply an adjustable ramp to the i sense pin gnd i sense comp error am p r s r f c f r 2r 1v current sense comparator 4.7k 1k error amp ad j ust 4.7k 2n2222 100k 5k i sense adjust comp v fb i sense r t /c t gnd v re f v cc output 0.1 1w v cc v ref 0.1 0.5ma v fb comp error am p gnd r t /c t v ref c t r t
amc3842b/43b/44b/45b copyright ? 2006 addtek corp. 8 dd019_f -- october 2006 application information (continued) fig. 5. shutdown techniques - there are two ways to shutdown the pw m controller: 1) raise the voltage at i sense above 1v or, 2) pull the comp below a voltage two diodes above ground. fig 6. slop compensation ? to achieve duty cycles over 50% for some applications, the above slope compensation technique is suggested by resistively summing a fraction of the oscillator ramp with the current sense signal. i sense shutdown v ref 500 ? to current sense resistor 330 ? 1k shutdown comp v ref r t /c t i sense r t c t 0.1
amc3842b/43b/44b/45b copyright ? 2006 addtek corp. 9 dd019_f -- october 2006 package 8-pin plastic dip inches millimeters min typ max min typ max a 0.355 0.365 0.400 9.02 9.27 10.16 b 0.240 0.250 0.280 6.10 6.35 7.11 c - 0.200 0.210 - 5.08 5.33 d 0.014 0.018 0.022 0.356 0.46 0.55 f 0.045 0.060 0.065 1.15 1.52 1.65 g - 0.100 - - 2.54 - h 0.050 - 0.090 1.27 - 2.29 j 0.008 0.010 0.015 0.20 0.25 0.38 k 0.115 0.130 0.150 2.92 3.30 3.81 l 0.300 bsc. 7.62 bsc. 1 b 5 4 8 c k f h g d a l m j m 0o 7o 15o 0o 7o 15o 8-pin plastic s.o.i.c. inches millimeters min typ max min typ max a 0.183 - 0.202 4.65 - 5.13 b 0.144 0.156 0.163 3.66 3.95 4.14 c 0.068 - 0.074 1.35 - 1.88 d 0.010 0.016 0.020 0.25 0.41 0.51 f 0.015 0.020 0.035 0.38 0.50 0.89 g 0.050 bsc 1.27 bsc j 0.007 - 0.010 0.19 - 0.25 k 0.005 - 0.010 0.13 - 0.25 l 0.189 - 0.205 4.80 - 5.21 m 0o - 8o 0o - 8o p 0.228 0.236 0.244 5.79 6.00 6.20 seating plan a d f p b k c m l j g
amc3842b/43b/44b/45b copyright ? 2006 addtek corp. 10 dd019_f -- october 2006 14-pin plastic s.o.i.c. inches millimeters min typ max min typ max a 0.336 - 0.344 8.54 - 8.74 b 0.159 - 0.158 3.81 - 4.01 c 0.053 - 0.069 1.35 - 1.75 d 0.014 - 0.018 0.35 - 0.46 f 0.026 - 0.030 0.67 - 0.77 g 0.050 bsc 1.27 bsc j 0.007 - 0.010 0.19 - 0.25 k 0.004 - 0.010 0.10 - 0.25 l 0.189 - 0.205 4.82 - 5.21 m - - 8o - - 8o p 0.228 - 0.244 5.79 - 6.20 seating plan f m l j g d p b a c k
amc3842b/43b/44b/45b copyright ? 2006 addtek corp. 11 dd019_f -- october 2006 important notice addtek reserves the right to make changes to its products or to discontinue any integrated circuit product or service without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing orders, that the information being relied on is current. a few applications using integrated circuit products may involve potential risks of death, personal injury, or severe property or environmental damage. addtek integrated circuit products are not designed, intended, authorized, or warranted to be suitable for use in life-support applications, devices or systems or other critical applications. use of addtek products in such applications is understood to be fully at the risk of the customer. in order to minimize risks associated with the customer?s applications, the customer should provide adequate design and operating safeguards. addtek assumes to no liability to customer product design or application support. addtek warrants the performance of its products to the specifications applicable at the time of sale. addtek corp. 9f, no. 20, sec. 3, bade rd., taipei, taiwan, 105 tel: 2-25700299 fax: 2-25700196

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