www.irf.com 1 data sheet no. pd60206 rev.d ir2085s & (pbf) high speed, 100v, self oscillating 50% duty cycle, half-bridge driver features simple primary side control solution to enable hal f-bridge dc-bus converters for 48v distributed systems with reduced component count and board space integrated 50% duty cycle oscillator & half-bridge driver ic in a single so-8 package programmable switching frequency with up to 500khz max per channel +/- 1a drive current capability optimized for low charge mosfets adjustable dead-time 50ns C 200ns floating channel designed for bootstrap operation up to +100vdc high and low side pulse width matching to +/- 25ns adjustable overcurrent protection undervoltage lockout and internal soft start also available leadfree product summary topology half-bridge v offset 100 v i o+ & i o- (typical) 1.0a & 1.0a f osc (max) 500khz deadtime 50ns C 200ns ho/lo pulse matching +/- 25ns package 8 - lead soic description the ir2085s is a self-oscillating half-bridge drive r ic with 50% duty cycle ideally suited for 36v C 7 5v half- bridge dc-bus converters. this product is also suitable for push-pull convert ers without restriction on input voltage. each channel frequency is equal to f osc, which can be set by selecting r t & c t, where f osc = 1/(2*r t .c t ). dead-time can be controlled through proper selectio n of c t and can range from 50ns to 200ns. internal soft-start increases the pulse width during power u p and maintains pulse width matching for the high a nd low outputs throughout the start up cycle. the ir20 85s initiates a soft start at power up and after ev ery overcurrent condition. undervoltage lockout prevent s operation if v cc is less than 7.5v. typical connection diagram
2 ir2085s & (pbf) www.irf.com absolute maximum ratings absolute maximum ratings indicate sustained limits beyond which damage to the device may occur. all voltage param- eters are absolute voltages referenced to com. all currents are defined positive into any lead. the thermal resistance and power dissipation ratings are measured under board mounted and still air conditions. symbol definition min. max. units v b high side floating supply voltage -0.3 150 v cc low side supply voltage 25 v s high side floating supply offset voltage v b - 25 v b + 0.3 v ho high side floating output voltage v b - 0.3 v b + 0.3 v lo low side output voltage -0.3 v cc + 0.3 osc osc pin voltage -0.3 v cc + 0.3 v cs cs pin voltage -0.3 v cc + 0.3 dv s /dt allowable offset voltage slew rate -50 +50 v/ns i cc supply current 20 ma p d package power dissipation 1.0w rth ja thermal resistance, junction to ambient 200 c/w t j junction temperature -55 150 t s storage temperature -55 150 t l lead temperature (soldering, 10 seconds) 300 c recommended operating conditions for proper operation the device should be used within the recommended conditions. vb high side floating supply voltage v dd -0.7 15 v s steady state high side floating supply offset voltage -5 100 v cc supply voltage 10 15 i cc supply current (note 2) 5 ma r t timing resistor 10 100 k c t timing capacitor 47 1000 pf fosc(max) operating frequency (per channel) 500 khz t j junction temperature -40 125 c vdc symbol definition min. max. units note1: care should be taken to avoid output switching conditions where the vs node flies inductively below ground by more than 5v. v
3 ir2085s & ( pbf) www.irf.com static electrical characteristics v bias (v cc , v bs ) = 12v, c load = 1000 pf and t a = 25 c unless otherwise specified. symbol definition min. typ. max. units test conditions v oh high level output voltage, (v bias - v o )1.5 v ol low level output voltage 0.1 i leak offset supply leakage current 50 i qbs quiescent v bs supply current 150 i qcc quiescent v cc supply current 1.5 ma v cs+ overcurrent shutdown threshold 250 300 350 mv v cs- overcurrent shutdown threshold 150 200 250 mv u vcc+ undervoltage positive going threshold 6.8 7.3 7.8 u vcc- undervoltage negative going threshold 6.3 6.8 7.3 u vbs+ high side undervoltage positive going threshold 6.8 7.3 7.8 u vbs- high side undervoltage negative going threshold 6.3 6.8 7.3 i o+ output high short circuit current 1.0 i o- output low short circuit current 1.0 dynamic electrical characteristics v bias (v cc , v bs ) = 12v, c load = 1000 pf, and t a = 25 c unless otherwise specified. v a symbol definition min. typ. max. units test conditions t r turn-on rise time 40 60 t f turn-off fall time 20 30 fosc per channel output frequency 500 khz tdt high/low output dead time 50 t dcs overcurrent shut down delay 200 pulse on cs pm high/low pulse width mismatch -25 25 v s = 0v ~ 100v nsec v s = 0v nsec c t =100pf, r t =10kohm v a
4 ir2085s & (pbf) www.irf.com lead assignments functional block diagrams lead definitions symbol description v cc logic supply gnd logic supply return vb high side floating supply v s floating supply return ho high side output lo low side output cs current sense input osc oscillator pin vb ho vs lo ir2085s vcc osc cs gnd 1 2 3 8 7 6 5 4 uvlo bias osc block pulse steering + ovc - uvlo and rs latch soft start 10pf vcc vref (250mv) vcc vb ho vs lo ct gnd ir2085s block diagram cs osc rt also available lead-free (pbf)
5 ir2085s & ( pbf) www.irf.com fig. 1 typical output frequency (-25 o c to 125 o c) fig. 2 typical dead time (@25 o c) fig. 3 typical dead time vs temperature 0 50 100 150 200 250 300 350 400 450 500 10 20 30 40 50 60 70 80 90 100 rt ( kohms ) frequency (khz) c t = 47pf c t = 100pf c t = 220pf c t = 470pf 50 75 100 125 150 175 200 225 250 10 20 30 40 50 60 70 80 90 100 rt ( kohms ) time (ns) c t = 470pf c t = 220pf c t = 100pf c t = 47pf 60 80 100 120 140 160 180 -40-20 0 20406080100120 temperature dead time (ns) dt(ct=100pf, rt=100k)
ir2085s& (pbf) 6 www.irf.co m pin descriptions cs: the input pin to the overcurrent comparator. excee ding the overcurrent threshold value specified in static electrical parameters section will termina te output pulses and start a new soft start cycle a s soon as the voltage on the pin reduce below the threshol d value. osc: the oscillator-programming pin. only two component s are required to program the internal oscillator frequency: a resistor connected between the v cc pin and the osc pin, and a capacitor connected fro m the osc to com. the approximate oscillator frequenc y is determined by the following simple formula: f osc = 1 / (2 r t c t ) where frequency is in hertz (hz), rt resistance in ohms ( ) and ct capacitance in farads (f). the recommended range of timing resistors is between 10 k and 100k and range of time capacitances is between 47pf and 470pf. the timing resistors less t han 10k should be avoided. the value of the timing capacitor determines the amount of dead time betwee n the two output drivers: lower the ct, shorter the dead time and vice versa. it is not recommended to use a timing capacitor below 47pf, for best performance keep the timing components physically a s close as possible to the ir2085s. separated ground and v cc traces to the timing components are encouraged. com: signal ground and power ground for all functions. due to high current and high frequency operation, a low impedance circuit board ground plane is highl y recommended. ho, lo: high side and low side gate drive pins. the high a nd low side drivers can directly drive the gate of a power mosfet. the drivers are capable of 1a pe ak source and sink currents. it is recommended that the high and low drive pins be very close to t he gates of the high side and low side mosfets to prevent any delay and distortion of the drive signa ls. v b : the high side power input connection. the high sid e supply is derived from a bootstrap circuit using a low-leakage schottky diode and a ceramic capacitor. to prevent noise, the schottky diode and bypass capacitor should be very close to the ir2085s. v s : the high side power return connection. v s should be connected directly to the source termina l of high side mosfet with a trace as short as possible. v cc : the ic bias input connection for the device. althou gh the quiescent v cc current is very low, total supply current will be higher, depending on the gat e charge of the mosfets connected to the ho and lo pins, and the programmed oscillator frequency, tota l v cc current is the sum of quiescent v cc current and the average current at ho and lo. knowing the opera ting frequency and the mosfet gate charge (qg) at selected v cc voltage, the average current can be calculated fro m: iave = 2 x qg x f osc to prevent noise problem, a bypass ceramic capacito r connected to v cc and com should be placed as close as possible to the ir2085s. ir2085s has an under voltage lookout feature for th e ic bias supply, v cc . the minimum voltage required on v cc to make sure that ic will work within specificatio ns must be higher than 8.5v (9.5v minimum v cc is recommended to prevent asymmetrical gates signal on ho and lo pins that are expected when v cc is between 7.5v and 8.5v).
9 ir2085s & ( pbf) www.irf.com 01-6027 01-0021 11 (ms-012aa) 8-lead soic 87 5 65 d b e a e 6x h 0.25 [.010] a 6 4 3 12 4. outline conforms to jedec outline ms-012aa. notes: 1. dimensioning & toleranc ing per asme y14.5m-1994. 2. controlling dimension: millimeter 3. dimensions are shown in millimeters [inches]. 7 k x 45 8x l 8x c y footprint 8x 0.72 [.028] 6.46 [.255] 3x 1.27 [.050] 8x 1.78 [.070] 5 dimension does not include mold protrusions. 6 dimension does not include mold protrusions. mold protrusions no t to exc eed 0.25 [.010]. 7 dimension is the length of lead for soldering to a substrate. mold protrusions no t to exc eed 0.15 [.006]. 0.25 [.010] cab e1 a a1 8x b c 0.10 [.004] e1 d e y b a a1 h k l .189 .1497 0 .013 .050 basic .0532 .0040 .2284 .0099 .016 .1968 .1574 8 .020 .0688 .0098 .2440 .0196 .050 4.80 3.80 0.33 1.35 0.10 5.80 0.25 0.40 0 1.27 basic 5.00 4.00 0.51 1.75 0.25 6.20 0.50 1.27 min max millimeters in c h e s min max dim 8 e c .0075 .0098 0.19 0.25 .025 basic 0.635 basic case outline
10 ir2085s & (pbf) www.irf.com this product has been designed and qualified for the industrial market. qualification standards can be found on irs web site http://www.irf.com/ . data and specifications subject to change without notice world headquarters: 233 kansas street, el segundo, california 90245 tel: (310) 252-7105 1/7/2006 leadfree part marking information lead free released non-lead free released part number date code irxxxxxx yww? ?xxxx pin 1 identifier ir logo lot code (prod mode - 4 digit spn code) assembly site code per scop 200-002 p ? marking code pkg desig s s part leadfree number part number ir2085s ir2085spbf IR2085STR IR2085STRpbf parts per tube 95 ------ parts per reel ------ 4000 ordering information pin count 8 8
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