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1 isl8204m, isl8206m caution: these devices are sensitive to electrostatic discharge; follow proper ic handling procedures. 1-888-intersil or 1-888-468-3774 | intersil (and design) is a registered trademark of intersil americas inc. copyright intersil americas inc. 2009, 2010. all rights reserved all other trademarks mentioned are the property of their respective owners. complete high efficiency dc/dc power module isl8204m, isl8206m the isl8204m, isl8206m is a family of pin-compatible power modules to the isl8201m. these are simple and easy to use, high power dc\dc modules and are ideal for a wide variety of applications. the isl820xm family of high current dc\dc step-down modules virtually eliminate design and manufacturing risks while dramatically improving time to market. the simplicity is in the family's "off the shelf" unassisted implementation. all you need is the isl820xm for the current requirement of your design, bulk input and output capacitors and one resistor, to program the output voltage, and you have a complete high current power design ready for your market. this family of buck converters is packaged in a thermally enhanced compact (15mmx15mm) over-molded qfn package that operates without a heat sink, even at full load over temperature. the package supports simple, reliable, automated assembly using standard surface mount equipment while making it easy to probe to all pins. the lack of a required heat dissipation layer, provides easy access to all pins and the limited number of the external components reduce the pcb to a component layer and a simple ground layer. additionally, each ic in the family is foot print compatible, making it easy to change your design to meet different power needs without changing your layout. one simple layout fits all. features ? complete switch mode power supply in one package - isl8204m - 4a with, 6.6a peak - isl8206m - 6a with, 8.8a peak ? single resistor sets vout +0.6v up to +6v @ 1% ? up to 95% efficiency ? overcurrent protection ? internal soft-start with pre-bias output start-up ? wide input voltage range from 1vdc to 20vdc ? fast transient response applications* (see page 18) ?servers ? telecom and datacom applications ? industrial equipment ? point of load regulation ? general purpose step-down dc/dc related literature* (see page 18) ? an1386 ?isl8201m, isl8204m, isl8206m eval1z evaluation board user?s guide? ?isim model - ( see respective device information page at intersil.com ) typical schematic derating curve (isl8206m 5v in ) v in (1v to 20v) v out (0.6v to 6.0v) r fb (sets v out ) 220 f fb isl8204m/6m power module v in v out p gnd 330 f p vcc c pvcc p vcc 10 f 0 1 2 3 4 5 6 7 60 70 80 90 100 110 ambient temperature (c) max load current (a) 0.6v 1.5v 3.3v table 1. r fb values for typical output voltages v out 0.6v 1.05v 1.2v 1.5v 1.8v 2.5v 3.3v 5v r fb open 13k 9.76k 6.49k 4.87k 3.09k 2.16k 1.33k december 16, 2010 fn6999.2
isl8204m, isl8206m 2 fn6999.2 december 16, 2010 simplified block diagram driver driver gate control logic por and soft-start ldo + - pwm controller + - 0.6v 0.4v oscillator dis + - pwm sample and hold + - 21.5a iset inhibit pvcc rfb-ti rset-in pgnd fb comp/en pvcc phase pgnd vout vin iset figure 1. internal block diagram ordering information part number (notes 1, 2, 3) part marking temp. range (c) package (rohs compliant) pkg. dwg. # ISL8204MIRZ isl8204m -40 to +85 15 ld qfn l15.15x15 isl8206mirz isl8206m -40 to +85 15 ld qfn l15.15x15 isl8204meval1z evaluation board isl8206meval1z evaluation board notes: 1. add ?-t? suffix for tape and reel. please refer to tb347 for details on reel specifications. 2. these intersil plastic packaged products employ special material sets, molding compounds and 100% matte tin plate plus anneal (e3) termination finish. these products do contain pb but they are rohs compliant by eu exemption 5 (pb in glass of cathode ray tubes, electronic components and fluorescent tubes ). these intersil rohs compliant products are compatible with both snpb and pb-free soldering operations. these intersil rohs compliant products are ms l classified at pb-free peak reflow temperatures that meet or exceed the pb-free requir ements of ipc/jedec j std-020. 3. for moisture sensitivity level (msl), please see device in formation page for isl8204m , isl8206m . for more information on msl please see techbrief tb363 . summary of features part number rated current (a) r iset (k ) ls fet r ds(on) (m ) max v out (v) isl8206m 6 4.12 15 6 isl8204m 4 2.87 15 6
isl8204m, isl8206m 3 fn6999.2 december 16, 2010 pin configuration isl8204m, isl8206m (15 ld qfn) top and 3d view pd2 pd3 pd4 pgnd pgnd pgnd pvcc nc iset nc vin pgnd nc phase pgnd vout comp/en fb 9 8765432 1 15 14 13 12 11 10 pd1 pin descriptions pin symbol description 1, 2, 3, 4 pgnd power ground pin for signal, input, and ou tput return path. pgnd needs to connect to one (or more) ground plane(s) immediately, which is recommended to minimize the effect of switching noise, copper losses, and maximize heat dissipation. range: 0v. 5 pvcc this pin provides the bias supply for isl8204m , isl8206m, as well as the low-side mosfet?s gate and high-side mosfet?s gate. if pvcc rises above 6.5v, an internal 5v regulator will supply to the internal logics bias (but high-side and low-side mosfet gate will still be sourced by pvcc). connect a well decoupled +5v or +12v supply to this pin. connect 1f ceramic capacitor to ground plane directly. range: 4.5v to 14.4v. 6, 8, 15 nc no internal connection. 7 iset the iset pin is the input for the overcurrent protection (ocp) setting, which compares the r ds(on) of the low-side mosfet to set the overcurrent thresh old. the isl8204m, isl8206m has an initial protect overcurrent limit. it has an integrated internal 4.12k / 2.87k resistor (r set-in ) between the iset and pgnd pins, which can prevent significant ov ercurrent impact to the module. one can also connect an additional resistor r set-ex between the iset pin and the pgnd pin in order to reduce the current limit point by paralleling. range: 0 to pvcc. 9 vin (pd1) power input pin. apply input voltage between the vi n pin and pgnd pin. it is recommended to place an input decoupling capacitor directly between th e vin pin and the pgnd pin. the input capacitor should be placed as closely as possible to the module. range: 1v to 20v. 10 phase (pd2) the phase pin is the switching node between the high and low side mosfet. it also returns the current path for the high side mosfet driver and detects the low-side mosfet drain voltage for the overcurrent limits point. range: 0v to 30v. 11 pgnd (pd3) power ground pin for signal, input, and output retu rn path. pgnd needs to connect to one (or more) ground plane(s) immediately, which is recommended to minimize the effect of switching noise, copper losses, and maximize heat dissipation. range: 0v. 12 vout (pd4) power output pin. apply output load between this pin and the pgnd pin. it is recommended to place a high frequency output decoupling capacitor directly between the vout pin and the pgnd pin. the output capacitor should be placed as closely as possible to the module. range: 0.6v to 6v.
isl8204m, isl8206m 4 fn6999.2 december 16, 2010 13 comp/en this is the multiplexed pin of the isl 8204m, isl8206m. during soft-sta rt and normal converter operation, this pin represents the output of the e rror amplifier. use comp/en in combination with the fb pin to compensate for the voltage control fee dback loop of the converter. pulling comp/en low (v endis = 0.4v nominal) will disable (shut-down) the co ntroller, which causes the oscillator to stop, and the high-side gate and low-side gate of the mosfets outputs to be held low. the external pull-down device will initially n eed to overcome a maximum of 5m a of comp/en output current. however, once the controller is disabled, the comp /en output will also be disabled, thus only a 20a current source will continue to draw current. range: 0v to 5v. 14 fb the fb pin is the output voltage adjustment of the isl8204m, isl8206m. it will regulate to 0.6v at the fb pin with respect to the pgnd pin. the isl8204m, isl820 6m has an integrated voltage dividing resistor. this is a precision 9.76k resistor (rfb-ti) between the vout and fb pins. different output voltages can be programmed with additional resistor s between fb to pgnd. range: 0.6v. pin descriptions (continued) pin symbol description
isl8204m, isl8206m 5 fn6999.2 december 16, 2010 absolute maximum ratings thermal information c omp/en to p gnd . . . . . . . . . . . . . . . . . . p gnd - 0.3v to +6v i set to p gnd . . . . . . . . . . . . . . . p gnd - 0.3v to p vcc + 0.3v p vcc to p gnd . . . . . . . . . . . . . . . . . . . p gnd - 0.3v to +15v p hase to p gnd (note 4) . . . . . . . . . . . . . . . . . -1.2v ~ +30v v in to p hase (note 4) . . . . . . . . . . . . . . . . . . -1.2v ~ +30v junction temperature, t j . . . . . . . . . . . . . . . . . . . . +125c storage temperature range, t stg . . . . . . -40c to +125c esd rating human body model (tested per jesd22-a114e) . . . . . 2kv machine model (tested per jesd22-a115-a) . . . . . . . 100v charge device model (tested per jesd22-c101c) . . . . 1kv latch up (tested per jesd-78b; class 2, level a) . . . 100ma thermal resistance (typical) ja (c/w) jc (c/w) 15 ld qfn (notes 5, 6) . . . . . . . . . 13.0 2.0 pb-free reflow profile . . . . . . . . . . . . . . . . . .see link below http://www.intersil.com/pbfree/pb-freereflow.asp recommended operating ratings input supply voltage (v in ) . . . . . . . . . . . . . . . +1v to +20v output voltage (v out ) . . . . . . . . . . . . . . . . . +0.6v to +6v p vcc fixed supply voltage . . . . . . . . . . . . . . . . . +5v or +12v wide range supply . . . . . . . . . . . . . . . +6.5v to +14.4v ambient temperature range (t a ) . . . . . . . . -40c to +85c caution: do not operate at or near the maximum ratings listed for extended periods of time. exposure to such conditions may adv ersely impact product reliability and result in failures not covered by warranty. notes: 4. v ds (drain to source) specification for internal high-side and low-side mosfet. 5. ja is measured in free air with the component mounted on a high effective thermal conductivity test board (i.e. 4-layer type without thermal vias ? see tech brief tb379 ) per jedec standards except that the top and bottom layers as sume solid planes. 6. for jc , the ?case temp? location is the center of the exposed metal pad on the package underside. electrical specifications t a = +25c. v in = 12v, v out = 1.5v. c in = 220fx1, 10f/ceramicx2, c out = 47fx8/ceramic. boldface limits apply over the operating temperature range, -40c to +85c. parameter symbol conditions min (note 8) typ max (note 8) units input characteristics input supply bias current i q(vin) i out = 0a, v out = 1.5v, v in = 12v, p vcc = 12v - 13 - ma input inrush current i inrush i out = 0a, v out = 1.5v, v in = 12v, p vcc = 12v - 140 - ma input supply current i s(vin) i out = 6a, v out = 1.5v, v in = 12v, p vcc = 12v - 0.86 - a i out = 4a, v out = 1.5v, v in = 12v, p vcc = 12v - 0.56 - a output characteristics output continuous current range i out(dc) v in = 12v, v out = 1.5v 0 - isl8206m 6 a isl8204m 0 - 4 a line regulation accuracy v out / v in v out = 1.5v, i out = 0a, v in = 3.3v to 20v, p vcc = 5v -0.1- % load regulation accuracy v out / i out i out = 0a to 6a/4a, v out = 1.5v, v in = 12v, p vcc = 12v - 0.5 - % peak-to-peak output ripple voltage v out isl8206m - 8 - mv i out = 6a v out = 1.5v, v in = 12v, p vcc = 12v isl8204m - 7 - mv i out = 4a v out = 1.5v, v in = 12v, p vcc = 12v
isl8204m, isl8206m 6 fn6999.2 december 16, 2010 dynamic characteristics voltage change for positive load step v out-dp i out = 0a to 4a. current slew rate = 2.5a/s, v in = 12v, v out = 1.5v, p vcc =12v - 30 - mv voltage change for negative load step v out-dn i out = 0a to 4a. current slew rate = 2.5a/s, v in = 12v, v out = 1.5v, p vcc =12v - 27 - mv voltage change for positive load step v out-dp i out = 0a to 6a. current slew rate = 2.5a/s, v in = 12v, v out = 1.5v, p vcc =12v - 43 - mv voltage change for negative load step v out-dn i out = 0a to 6a. current slew rate = 2.5a/s, v in = 12v, v out = 1.5v, p vcc =12v - 40 - mv controller pvcc supply current shutdown i pvcc_s p vcc = 12v; disabled (note 7) 4 5.2 7 ma supply voltage p vcc fixed 5v supply (note 7) 4.5 5.0 5.5 v wide range supply (note 7) 6.5 12.0 14.4 v p vcc operating current i pvcc i out = 6a, v out = 1.5v, v in = 12v 5v supply - 14 - ma 12v supply - 25 - ma i out = 4a, v out = 1.5v, v in = 12v 5v supply - 14 - ma 12v supply - 25 - ma rising p vcc threshold v porr (note 7) 3.9 4.1 4.3 v p vcc power-on-reset threshold hysteresis v porh (note 7) 0.30 0.35 0.40 v oscillator frequency f osc (note 7) 510 600 660 khz internal resistor between v out and fb pins r fb-ti (note 7) 9.66 9.76 9.86 k disabled threshold voltage (comp/en) v endis (note 7) 0.375 0.4 0.425 v reference voltage v ref (note 7) - 0.6 - v reference voltage tolerance 0c to +70c (note 7) -1.0 - +1.0 % -40c to +85c (note 7) -1.5 - +1.5 % fault protection internal resistor between i set and p gnd pins r set-in isl8206m - 4.12 - k isl8204m - 2.87 - k i set current source i set (note 7) 18.0 21.5 23.5 a notes: 7. parameters are 100% tested for internal ic/component prior to module assembly. 8. parameters with min and/or max limits are 100% tested at +2 5c, unless otherwise specified. temperature limits established by characterization and are not production tested. electrical specifications t a = +25c. v in = 12v, v out = 1.5v. c in = 220fx1, 10f/ceramicx2, c out = 47fx8/ceramic. boldface limits apply over the operating temperature range, -40c to +85c. (continued) parameter symbol conditions min (note 8) typ max (note 8) units
isl8204m, isl8206m 7 fn6999.2 december 16, 2010 pgnd phase vin vout fb comp/en iset pvcc 1.8v 10a v out c out1 22f 6.3v x3 r fb 4.87k c pvcc isl8204m, isl8206m (+5v/+12v) v in c in (cer) 10f 25v x2 c in (bulk) 220f c out2 330f figure 2. test circuit for all performance and derating graphs typical performance characteristics efficiency performance t a = +25c, v in = p vcc (p vcc = 5v for 18v in ), c in = 220fx1, 10f/ceramic x 2, c out = 330f (esr = 10m ), 22f/ceramic x 3. th e efficiency equation is: figure 3. efficiency vs load current (5v in ) figure 4. efficiency vs load current (12v in ) figure 5. efficiency vs load current (18v in ) figure 6. 1.2v transient response efficiency output power input power ----------------------------------------- p out p in --------------- - v out xi out () v in xi in () -------------------------------------- === 60 65 70 75 80 85 90 95 100 0246 load current (a) efficiency (%) 13 5 3.3v 2.5v 1.5v 1.2v 0.8v 60 65 70 75 80 85 90 95 100 load current (a) efficiency (%) 0246 13 5 3.3v 2.5v 1.5v 1.2v 0.8v 5.0v 60 65 70 75 80 85 90 95 100 0 load current (a) efficiency (%) 5.0v 3.3v 2.5v 1.5v 1.2v 123456 v in = 12v v out = 1.2v i out = 0a to 5a i out v out
isl8204m, isl8206m 8 fn6999.2 december 16, 2010 typical performance characteristics (continued) transient response performance t a = +25c, v in = 12v, p vcc = 12v, c in = 220fx1, 10f/ceramic x 2, c out =330f (esr = 10m ), 22f/ceramic x 3 i out = 0a to 5a, current slew rate = 2.5a/s figure 7. 1.5v transient response figure 8. 1.8v transient response figure 9. 2.5v transient response figure 10. 3.3v transient response v in = 12v v out = 1.5v i out = 0a to 5a v out i out v in = 12v v out = 1.8v i out = 0a to 5a v out i out v in = 12v v out = 2.5v i out = 0a to 5a v out i out v in = 12v v out = 3.3v i out = 0a to 5a v out i out
isl8204m, isl8206m 9 fn6999.2 december 16, 2010 typical performance characteristics (continued) output ripple performance t a = +25c, v in = 12v, p vcc = 12v, c in = 220fx1, 10f/ceramic x 2, c out = 330f (esr = 10m ), 22f/ceramic x 3 i out = 0, 4, 6a figure 11. 1.2v output ripple figure 12. 1.5v output ripple figure 13. 2.5v output ripple figure 14. 3.3v output ripple v out 6a v out 4a v out 0a v out 6a v out 4a v out 0a v out 6a v out 4a v out 0a v out 6a v out 4a v out 0a
isl8204m, isl8206m 10 fn6999.2 december 16, 2010 reference circuitry for general applications 1. single power supply figure 15 shows the isl8204m, isl8206m application schematic for input voltage +5v or +12v. the pvcc pin can connect to the input supply directly. 2. separated power supply figure 16 shows the isl8204m, isl8206m application schematic for wide input voltages from +1v to +20v. the p vcc supply can source +5v/+12v or +6.5v to 14.4v. applications information the typical isl8204m, isl8206m application schematic for input voltage +5v or +12v is shown in figure 15. external component selection is primarily determined by the maximum load current and input/output voltage. programming the output voltage the isl8204m, isl8206m has an internal 0.6v 1.5% reference voltage. programming the output voltage requires a dividing resistor (r fb ). the output voltage can be calculated as shown in equation 1: note: isl8204m, isl8206m has integrated 9.76k resistance into the module (dividing resistor for top side). the resistance corresponding to different output voltages is as shown in table 2: initialization (por and ocp sampling) figure 17 shows a start-up waveform of isl8204m, isl8206m. the power-on-reset (por) function continually monitors the bias voltage at the pvcc pin. once the rising por threshold has exceeded 4v (v porr nominal), the por function initiates the overcurrent protection (ocp) sample and hold operation (while comp/en is ~1v). when the sampling is complete, v out begins the soft-start ramp. if the comp/en pin is held low during power-up, the initialization will be delayed until the comp/en is released and its voltage rises above the v endis trip point. figure 18 and figure 19 show a typical power-up sequence in more detail. th e initialization starts at t 0 , when either p vcc rises above v porr , or the comp/en pin is released (after por). the comp/en will be pulled up by an internal 20a current source, however, the timing will not begin until the comp/en exceeds the v endis trip point (at t 1 ). the external capacitance of the disabling device, as well as the compensation capacitors, will determine how quickly the 20a current source will charge the comp/en pin. with typical values, it should figure 15. typical application schematic pgnd fb comp/en vin vout phase iset pvcc (+5v/+12v) v in v out c in c out r fb r set-ex c pvcc isl8204m, isl8206m figure 16. wide input voltage application schematic pgnd fb comp/en vin vout phase iset pvcc (+1v to +20v) v in v out c in c out r fb r set-ex c pvcc (+5v/+12v) or (+6.5v to 14.4v) p vcc isl8204m, isl8206m v out 0.6 1 9.76k r fb -------------- - + ?? ?? = (eq. 1) table 2. resistance to output voltages v out 0.6v 0.8v 1.05v 1.2v r fb open 28.7k 13k 9.76k v out 1.5v 1.8v 2.5v 3.3v r fb 6.49k 4.87k 3.09k 2.16k v out 5v 6v r fb 1.33k 1.07k figure 17. por and soft-start operation v out comp/en ~4v pvcc
isl8204m, isl8206m 11 fn6999.2 december 16, 2010 add a small delay compared to the soft-start times. the comp/en will continue to ramp to ~1v. from t 1 , there is a nominal 6.8ms delay, which allows the pvcc pin to exceed 6.5v (if rising up towards 12v), so that the internal bias regulator can turn on cleanly. at the same time, the iset pin is initialized by disabling the low-side gate driver and drawing i set (nominal 21.5a) through r seti . this sets up a voltage that will represent the i set trip point. at t 2 , there is a variable time period for the ocp sample and hold operation (0.0ms to 3.4ms nominal; the longer time occurs with the higher overcurrent setting). the sample and hold operation uses a digital counter and dac to save the voltage, so the stored value does not degrade, as long as the p vcc is above v porr (see ?overcurrent protection (ocp)? on page 12 for more details on the equations and variables). upon the completion of sample and hold at t 3 , the soft-start operation is initiated, and the output voltage ramps up between t 4 and t 5 . soft-start and pre-biased outputs the soft-start internally ramps the reference on the non-inverting terminal of the error amp from 0v to 0.6v in a nominal 6.8ms. the output voltage will follow the ramp from zero to it?s final value in the same 6.8ms (the actual ramp seen on v out will be less than the nominal time), due to some initialization timing between t 3 and t 4 . the ramp is created digitally, so there will be 64 small discrete steps. there is no simple way to change this ramp rate externally. after an initialization period (t 3 to t 4 ), the error amplifier (comp/en pin) is enabled and begins to regulate the converter's output voltage during soft-start. the oscillator's triangular waveform is compared to the ramping error amplifier volt age. this generates phase pulses of increasing width that charge the output capacitors. when the internally generated soft-start voltage exceeds the reference voltage (0.6v), the soft-start is complete and the output should be in regulation at the expected voltage. this method provides a rapid and controlled output voltage rise; there is no large inrush current charging the output capacitors. the entire start-up sequence from por typically takes up to 17ms; up to 10.2ms for the delay and ocp sample and 6.8ms for the soft-start ramp. figure 20 shows the normal curve for start-up; initialization begins at t 0 , and the output ramps between t 1 and t 2 . if the output is pre-biased to a voltage less than the expected value (as shown figure 21), neither internal mosfet will turn on until the soft-start ramp voltage exceeds the output; v out starts seamlessly ramping from there. figure 18. i set and soft-start operation figure 19. i set and soft-start operation t 0 t 1 comp/en iset vout t 0 t 1 comp/en v out iset comp/en v out iset t 2 t 3 t 4 t 5 3.4ms 3.4ms start switching figure 20. normal start-up
isl8204m, isl8206m 12 fn6999.2 december 16, 2010 if the output is pre-biased to a voltage above the expected value (as shown figure 22), neither mosfet will turn on until the end of the soft-start, at which time it will pull the output voltage down to the final value. any resistive load connected to the output will help pull down the voltage (at the rc rate of the r of the load and the c of the output capacitance). if v in for the synchronous buck converter is from a different supply that comes up after p vcc , the soft-start will go through its cycle, but with no output voltage ramp. when v in turns on, the output will follow the ramp of the v in from zero up to the final expected voltage (at close to 100% duty cycle, with comp/en pin >4v). if v in is too fast, there may be excessive inrush current charging the output capacitors (only the beginning of the ramp, from zero to v out matters here). if this is not acceptable, then consider changing the sequencing of the power supplies, sharing the same supply, or adding sequencing logic to the comp/en pin to delay the soft-start until the v in supply is ready (see ?input voltage considerations? on page 14). if isl8204m, isl8206m is disabled after soft-start (by pulling comp/en pin low), and afterwards enabled (by releasing the comp/en pin), th en the full initialization (including ocp sample) will take place. however, there is no new ocp sampling during overcurrent retries. if the output is shorted to gnd during soft-start, the ocp will handle it, as described in the next section. overcurrent protection (ocp) the overcurrent function protects the converter from a shorted output by using the low side mosfet on-resistance, r ds(on) , to monitor the current. a resistor (r set ) programs the overcurrent trip level. this method enhances the converter's efficiency and reduces cost by eliminating a current sensing resistor. if overcurrent is detected, the output immediately shuts off. it cycles the soft-start function in a hiccup mode (2 dummy soft-start time-outs, then up to one real one) to provide fault protection. if the shorted condition is not removed, this cycle will continue indefinitely. following por (and 6.8ms delay), the isl8204m, isl8206m initiates the overcurrent protection sample and hold operation. the low side gate driver is disabled to allow an internal 21.5a current source to develop a voltage across r set . the isl8204m, isl8206m samples this voltage (which is referenced to the pgnd pin) at the iset pin, and holds it in a counter and dac combination. this sampled voltage is held internally as the overcurrent set point, for as long as power is applied, or until a new sample is taken after coming out of a shut-down. the actual monitoring of the low side mosfet on-resistance starts 200ns (nominal) after the edge of the internal pwm logic signal (that creates the rising external low side gate signal). this is done to allow the gate transition noise and ringing on the phase pin to settle out before monitoring. the monitoring ends when the internal pwm edge (and thus low side gate signal) goes low. the ocp can be detected anywhere within the above window. if the converter is running at high duty cycles, around 75% for 600khz operation, then the low side gate pulse width may not be wide enough for the ocp to properly sample the r ds(on) . for those cases, if the low side gate signal is too narrow (or not there at all) for 3 consecutive pulses, then the third pulse will be stretched and/or inserted to the 425ns minimum width. this allows for ocp monitoring every third pulse under this condition. this can introduce a small pulse-width error on the output voltage, which will be corrected on the next pulse; and the output ripple voltage will have an unusual 3-clock pattern, which may look like jitter. figure 21. pre-biased start-up figure 22. pre-biased start-up - overcharged v out v out 500mv/div
isl8204m, isl8206m 13 fn6999.2 december 16, 2010 the overcurrent function will trip at a peak inductor current (i peak ) determined by equation 2: where: i set is the internal i set current source (21.5a typical). r set is equivalent resistance between iset and pgnd pins. r ds(on) is typically 15m @ (v pvcc = v gs = 10v, i ds = 15a) and 18m @ (v pvcc = v gs = 4.5v, i ds = 15a). note: isl8204m, isl8206m has integrated 4.12k / 2.87k resistance (r set-in ). therefore, the equivalent resistance of r set can be expressed in equation 3: the scale factor of 2 doubles the trip point of the mosfet voltage drop, compared to the setting on the r set resistor. the oc trip point varies in a system mainly due to the mosfet r ds(on) variations (i.e. over process, current and temperature). to avoid overcurrent tripping in the normal operating load range, find the r set resistor from equation 3, and use the following values: 1. the maximum r ds(on) at the highest junction temperature 2. the minimum i set from the ?electrical specifications? table on page 3. 3. determine i peak for: where i l is the output inductor ripple current. in a high input voltage, high output voltage application, such as 20v input to 5v output, the inductor ripple becomes excessive due to the fix internal inductor value. in such applications, the output curren t will be limited from the rating to approx imately 70% of the module?s rated current. the relationships between the external r set values and the typical output current i out(max) ocp levels for isl8206m are as follows: the range of allowable voltages detected (2 x i set x r set ) is 0mv to 475mv. if the voltage drop across r set is set too low, the following conditions may occur: (1) continuous ocp tripping an d retry and (2) it may be overly sensitive to system noise and inrush current spikes, so it should be avoided. the maximum usable setting is around 0.2v across r set (0.4v across the mosfet); values above this might disable the protection. any voltage drop across r set that is greater than 0.3v (0.6v mosfet trip point) will disable the ocp. note that conditions during power-up or during a retry may look different than normal operation. during power-up in a 12v system, the isl8204m, isl8206m starts operation just above 4v; if the supply ramp is slow, the soft-start ramp might be over well before 12v is reached. therefore, with low side gate drive voltages, the r ds(on) of the mosfet will be higher during power- up, effectively lowering the ocp trip. in addition, the ripple current will likely be different at a lower input voltage. another factor is the digital nature of the soft- start ramp. on each discrete voltage step, there is in effect, a small load transient and a current spike to charge the output capacitors. the height of the current spike is not controlled, however, it is affected by the step size of the output an d the value of the output capacitors, as well as the internal error amp compensation. therefore, it is possible to trip the overcurrent with inrush current, in addition to the normal load and ripple considerations. figure 23 shows the output response during a retry of an output shorted to pgnd. at time t 0 , the output has been turned off due to sensin g an overcurrent condition. there are two internal soft-start delay cycles (t 1 and t 2 ) to allow the mosfets to cool down in order to keep the average power dissipation in retry at an acceptable level. at time t 2 , the output starts a normal soft-start cycle, and the output tries to ramp. if the short is still applied and the curr ent reaches the i set trip point any time during the soft-start ramp period, the output will shut off and return to time t 0 for another delay cycle. the retry period is thus tw o dummy soft-start cycles plus one variable (which depends on how long it takes to trip the sensor each time). figure 23 shows an example where the output gets about half-way up before shutting down; therefore, the retry (or hiccup) time will be around 17ms. the minimum should be nominally 13.6ms and the maximum 20.4ms. if the short condition is finally removed, the output should ramp up normally on the next t 2 cycle. table 3. r set ( ) ocp (a) @ v in = 12v, p vcc = 5v ocp (a) @ v in = 12v p vcc = 12v open 8.1 8.8 50k 7.5 8.1 20k 6.6 7.4 10k 5.5 6.4 5k 4.4 5.0 i peak 2i set r set r ds on () ------------------------------------------- - = (eq. 2) r set r set-ex r set-in r set-ex r set-in + ------------------------------------------------------- = (eq. 3) i peak i out max () i l () 2 ------------- + > (eq. 4)
isl8204m, isl8206m 14 fn6999.2 december 16, 2010 starting up into a shorted load looks the same as a retry into that same shorted load. in both cases, ocp is always enabled during soft-start; once it trips, it will go into retry (hiccup) mode. the retry cycle will always have two dummy time-outs, plus whatever fraction of the real soft-start time passes before the detection and shutoff. at that point, the logic immediately starts a new two dummy cycle time-out. input voltage considerations figure 16 shows a standard configuration where p vcc is either 5v (10%) or 12v (20%). in each case, the gate drivers use the p vcc voltage for low side gate and high side gate driver. in addition, p vcc is allowed to work anywhere from 6.5v up to the 14.4v maximum. the p vcc range between 5.5v and 6.5v is not allowed for long-term reliability reasons, but transitions through it to voltages above 6.5v are acceptable. there is an internal 5v regulator for bias, which turns on between 5.5v and 6.5v. some of the delay after por is there to allow a typical po wer supply to ramp-up past 6.5v before the soft-start ra mps begins. this prevents a disturbance on the output, due to the internal regulator turning on or off. if the transition is slow (not a step change), the disturbance sh ould be minimal. thus, while the recommenda tion is to not have the output enabled during the transition through this region, it may be acceptable. the user should monitor the output for their application to see if there is any problem. if p vcc powers up first and v in is not present by the time the initialization is done, then the soft-start will not be able to ramp the output, and the output will later follow part of the v in ramp when it is applied. if this is not desired, then change the sequencing of the supplies, or use the comp/en pin to disable v out until both supplies are ready. figure 24 shows a simple sequencer for this situation. if p vcc powers up first, q 1 will be off, and r 3 pulling to p vcc will turn q 2 on, keeping the isl8204m, isl8206m in shut-down. when v in turns on, the resistor divider r 1 and r 2 determine when q 1 turns on, which will turn off q 2 and release the shut-down. if v in powers up first, q 1 will be on, turning q 2 off; so the isl8204m, isl8206m will start-up as soon as p vcc comes up. the v endis trip point is 0.4v nominal, so a wide variety of n-mosfet or npn bjt or even some logic ic's can be used as q 1 or q 2 . however, q 2 must be low leakage when off (open-drain or open-collector) so as not to interfere with the comp output. q 2 should also be placed near the comp/en pin. the v in range can be as low as ~1v (for v out as low as the 0.6v reference) and as high as 20v. there are some restrictions for running high v in voltage. the maximum phase voltage is 30v. v in + p vcc + any ringing or other transients on the phase pin must be less than 30v. if v in is 20v, it is recommended to limit p vcc to 5v. switching frequency the switching frequency is a fixed 600khz clock, which is determined by the internal oscillator. however, all of the other timing mentioned (por delay, ocp sample, soft-start, etc.) is independ ent of the clock frequency (unless otherwise noted). selection of the input capacitor the input filter capacitor should be based on how much ripple the supply can tolerate on the dc input line. the larger the capacitor, the less ripple expected but consideration should be taken for the higher surge current during power-up. the isl8204m, isl8206m provides the soft-start function that controls and limits the current surge. the value of the input capacitor can be calculated by equation 5: where: c in is the input capacitance (f) i in is the input current (a) t is the turn on time of the high-side switch (s) v is the allowable peak-to-peak voltage (v) figure 23. overcurrent retry operation t 2 t 1 t 0 v out ~6.8ms ~6.8ms figure 24. sequence circuit v in pvcc r 1 r 3 r 2 q 1 q 2 to comp/en c in i in t v ------------------- = (eq. 5)
isl8204m, isl8206m 15 fn6999.2 december 16, 2010 in addition to the bulk capacitance, some low equivalent series inductance (esl) ceramic capacitance is recommended to decouple between the drain terminal of the high side mosfet and the source terminal of the low side mosfet. this is used to reduce the voltage ringing created by the switching current across parasitic circuit elements. output capacitors the isl8204m, isl8206m is designed for low output voltage ripple. the output voltage ripple and transient requirements can be met with bulk output capacitors (c out ) with low enough equivalent series resistance (esr). c out can be a low esr tantalum capacitor, a low esr polymer capacitor or a ceramic capacitor. the typical capacitance is 330f and decoupled ceramic output capacitors are used. the internally optimized loop compensation provides sufficient stability margins for all ceramic capacitor applications with a recommended total value of 400f. additional output filtering may be needed if further reduction of output ripple or dynamic transient spike is required. layout guide to achieve stable operation, low losses and good thermal performance some layout considerations are necessary. ? the ground connection between pin 11 and pin 1 to 4 should be a solid ground plane under the module. ? place a high frequency ceramic capacitor between (1) vin and pgnd (pin 11) and (2) pvcc and pgnd (pin 1 to 4) as close to the module as possible to minimize high frequency noise ? use large copper areas for a power path (vin, pgnd, vout) to minimize conduction loss and thermal stress. also, use multiple vias to connect the power planes in different layers. ? keep the trace connection to the feedback resistor short ? avoid routing any sensitive signal traces near the phase node figure 25. recommended layout v out r fb pgnd c pvcc v in pgnd c in c out1 (decouple)
isl8204m, isl8206m 16 fn6999.2 december 16, 2010 thermal considerations experimental power loss curves along with ja from thermal modeling analysis can be used to evaluate the thermal consideration for the module. the derating curves are derived from the maximum power allowed while maintaining the temperature below the maximum junction temperature of +125c. the power loss and derating curves apply for both isl8206m, and isl8204m. the loss at 4a can be found by tracing the power loss curve up at the load current of 4a. in actual applications, other heat sources and design margins should be considered. package description the structure of isl8204m, isl8206m belongs to the quad flat-pack no-lead package (qfn). this kind of package has advantages, such as good thermal and electrical conductivity, low weight and small size. the qfn package is applicable for surface mounting technology and is being more readily used in the industry. the isl8204m, isl8206m contains several types of devices, including resistors, capacitors, inductors and control ics. the isl8204m, isl8206m is a copper lead-frame based pa ckage with exposed copper thermal pads, which have go od electrical and thermal conductivity. the copper lead frame and multi-component assembly is overmolded with polymer mold compound to protect these devices. the package outline and typical pcb layout pattern design and typical stencil patte rn design are shown in the package outline drawing l 15.15x15 on page 19. the module has a small size of 15mmx15mmx3.5mm. figure 25 shows typical reflow profile parameters. these guidelines are general design rules. users can modify parameters according to their application. pcb layout pattern design the bottom of isl8204m, isl8206m is a lead-frame footprint, which is attached to the pcb using a surface mounting process. the pcb layout pattern is shown in the package outline drawing l15.15x15 on page 19. the pcb layout pattern is essentially 1:1 with the qfn exposed pad and i/o termination dimensions, except for the pcb lands being a slight ly extended distance of 0.2mm (0.4mm max) longer than the qfn terminations, which allows for solder filleting around the periphery of the package. this ensures a more complete and inspectable solder joint. the thermal lands on the pcb layout should match 1:1 with the package exposed die pads. figure 26. power loss vs load current (5v in ) figure 27. derating curve (5v in ) figure 28. power loss vs load current (12v in ) figure 29. derating curve (12v in ) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 load current (a) loss (w) 0246 13 5 3.3v 1.5v 0.6v 0 1 2 3 4 5 6 7 60 70 80 90 100 110 ambient temperature (c) max load current (a) 0.6v 1.5v 3.3v 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 load current (a) loss (w) 3.3v 2.5v 5.0v 0.6v 1.5v 0246 13 5 0 1 2 3 4 5 6 7 60 70 80 90 100 110 ambient temperature (c) max load current (a) 0.6v 5.0v 3.3v 2.5v 1.5v
isl8204m, isl8206m 17 intersil products are manufactured, assembled and tested utilizing iso9000 qu ality systems as noted in the quality certifications found at www.intersil.com/design/quality intersil products are sold by description only. intersil corporation reserves the right to make changes in circuit design, soft ware and/or specifications at any time without notice. accordingly, th e reader is cautioned to verify that data sheets are current before placing orders. information furnished by intersil is believed to be accura te and reliable. however, no re sponsibility is assumed by inte rsil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which ma y result from its use. no licen se is granted by implication o r otherwise under any patent or patent rights of intersil or its subsidiaries. for information regarding intersil corporation and its products, see www.intersil.com fn6999.2 december 16, 2010 for additional products, see www.intersil.com/product_tree thermal vias a grid of 1.0mm to 1.2mm pitch thermal vias, which drops down and connects to buried copper plane(s), should be placed under the thermal land. the vias should be about 0.3mm to 0.33mm in diameter with the barrel plated to about 1.0 ounce copper. although adding more vias (by decreasing via pitch) will improve the thermal performance, diminishing returns will be seen as more and more vias are added. simply use as many vias as practical for the thermal land size and your board design rules allow. stencil pattern design reflowed solder joints on the perimeter i/o lands should have about a 50m to 75m (2mil to 3mil) standoff height. the solder paste stencil design is the first step in developing optimized, reliable solder joints. stencil aperture size to land size ratio should typically be 1:1. the aperture width may be reduce d slightly to help prevent solder bridging between adjacent i/o lands. to reduce solder paste volume on the la rger thermal lands, it is recommended that an array of smaller apertures be used instead of one large aperture. it is recommended that the stencil printing area cover 50% to 80% of the pcb layout pattern. a typical solder stencil pattern is shown in the package outline drawing l15.15x15 on page 19. the gap width between pad to pad is 0.6mm. the user should consider the symmetry of th e whole stencil pattern when designing its pads. a laser cut, stainless steel stencil with electropolished trapezoidal walls is recommended. electropolishing ?smooths? the aperture walls resulting in reduced surface friction and better paste release which reduces voids. using a trapezoidal section aperture (tsa) also promotes paste release and forms a "brick like" paste deposit that assists in firm component placement. a 0.1mm to 0.15mm stencil thickness is recommended for this large pitch (1.3mm) qfn. reflow parameters due to the low mount height of the qfn, "no clean" type 3 solder paste per ansi/j-std-005 is recommended. nitrogen purge is also re commended during reflow. a system board reflow profile depends on the thermal mass of the entire populated board, so it is not practical to define a specific soldering profile ju st for the qfn. the profile given in figure 30 is provided as a guideline, to be customized for varying manufacturing practices and applications. figure 30. typical reflow profile 0300 100 150 200 250 350 0 50 100 150 200 250 300 temperature (c) duration (s) slow ramp (3c/s max) and soak from +100c to +180c for 90s~120s ramp rate 1.5c from +70c to +90c peak temperature +230c~+245c; typically 60s-70s above +220c keep less than 30s within 5c of peak temp.
isl8204m, isl8206m 18 fn6999.2 december 16, 2010 products intersil corporation is a leader in the design and manuf acture of high-performance analog semiconductors. the company's products address some of the industry's fastest growing markets, such as, flat panel displays, cell phones, handheld products, and notebooks. intersil's product families address power management and analog signal processing functions. go to www.intersil.com/products for a complete list of intersil product families. *for a complete listing of applications, related documentat ion and related parts, please see the respective device information page on intersil.com: isl8204m , isl8206m to report errors or suggestions for this datasheet, please go to www.intersil.com/askourstaff fits are available from our website at http://rel.intersil.com/reports/search.php revision history the revision history provided is for informat ional purposes only and is believed to be accurate, but not warranted. please go t o web to make sure you have the latest rev. date revision change 10/13/10 fn6999.2 updated the simplified block diagram fi gure 1 on page 2. difference is on the ground connection near rset-in. 9/20/10 page 17 under reflow parameters corrected number from ?ansi/j-std-00? to ?ansi/j-std-005?. changed note 2 in ordering information from ?the se products do contain pb but they are rohs compliant by eu exemption 5 (pb in gl ass of cathode ray tubes, electronic components and fluorescent tubes?. to ?these intersil plastic packag ed products employ special material sets, molding compounds and 100% matte tin plate plus anneal (e3) termination finish. these products do contain pb but they are rohs compliant by eu exemption 5 (pb in glass of cathode ray tubes, electronic components and fluorescent tubes ). these intersil rohs compliant products are compat ible with both snpb and pb-free soldering operations. these intersil rohs compliant produc ts are msl classified at pb-free peak reflow temperatures that meet or exceed the pb-free requirements of ipc/jedec j std-020. 9/3/10 page 1 replaced note 2 with the followin g: ?these products do contain pb but they are rohs compliant by eu exemption 5 (pb in glass of cathode ray tubes, electronic comp onents and fluorescent tubes ).? page 4 -add theta jc_bottom : 2.0 c/w -changed note 5: theta-ja is measured in free air with the component mounted on a high effective thermal conductivity test board (i.e. 4-layer type without thermal vias ? see tech brief tb379) per jedec standards except that the top and bottom layers assume solid planes. -add note: for theta-jc_bottom, the ?case temp? location is the center of the package underside. 9/1/10 replaced pod with the following change: corrected pad width dimens ion in land pattern on page 2 from 3.10 to 3.00 (7th line down from top in column on left handside) 8/20/10 -changes to figure 30 as follows: from: ? slow ramp and soak ?? to: ? slow ramp (3c/sec max) and soak ? ? from: ?peak temperatur e =230 ? 245c; keep about 30s above 220 ? to: ?peak temperature = 230-245c ; typicall y 60s-70s above 220. keep less than 30s within 5 degrees of peak temp -changed the graphic to look more like 65 sec above 220 and 25 sec within 5 c of peak. -updated pod to most recent ve rsion -added dimension 15.8+/- 0.2to bottom an d right side of top view. changed 0.4+/-0.2 to (33x0.4) added eval boards to ordering information 2/25/10 fn6999.1 updated title. replaced figures 1 and 5. 12/21/09 fn6999.0 initial release.
isl8204m, isl8206m 19 fn6999.2 december 16, 2010 package outline drawing l15.15x15 15 lead quad flat no-lead plastic package (punch qfn) rev 3, 8/10 bottom view side view top view 0.2 s 0.05 s s 5 10 9 8 7 6 3 4 2 5 ab s m 0.05 11 10 11 9 7 8 6 ab 0.2 s x4 12 4 3 2 14 13 1 15 7x 1.70 1.125 23x 1.30 0.5 5 all around 15.00.2 13 pin 1 index area 1514 1 12 (33x0.4) 15.00.2 2.10 33x 0.5 5.80 4x 7.90 21x 1.0 4.60 2.20 3.0 4.80 2x 13.80 9.0 5.0 45 3.10 5.90 3.80 1.30 2x 7.70 3.50.2 0.90 1.90 2.90 0.30 2.10 1.80 4x 1.90 6.90 5.10 11x 0.80 6.0000 located within the zone indicated. the pin #1 indentifier may be unless otherwise specified, tolerance : decimal 0.05; the configuration of the pin #1 identifier is optional, but must be 3. either a mold or mark feature. 2. dimensions are in millimeters. 1. notes: body tolerance 0.1mm 15.80.2 15.80.2
isl8204m, isl8206m 20 fn6999.2 december 16, 2010 6.18 0.00 4.12 3.48 2.82 2.18 1.52 0.88 0.22 0.42 2.38 3.02 3.68 4.32 4.98 5.62 6.28 6.92 8.30 4.90 2.80 1.60 1.00 1.35 2.18 4.30 5.90 6.60 0.00 stencil pattern with square pads-2 0.88 0.0 3.00 3.50 8.30 typical recommended land pattern 8.30 1.70 2.20 4.00 3.00 0.90 0.90 0.0 2.20 0.40 0.40 1.70 2.20 0.0 1.20 5.20 3.10 5.60 4.60 8.30 8.30 package boundary 4.80 6.10 5.60 4.30 4.30 6.70 4.90 stencil pattern with square pads-1 2.50 0.90 0.00 1.40 2.00 4.30 8.30 3.02 4.63 5.27 7.00 3.50 4.15 0.42 2.38 0.22 0.00 1.80 2.20 3.70 4.30 6.60 0.00 0.60 1.20 6.60 3.40 4.80 0.32 0.30 1.63 4.88 5.53 2.93 2.28 0.98 0.33 0.00 6.60 4.20 3.75 0.30 3.15 3.60 0.00 6.08 0.97 1.62 5.52 4.87 4.22 3.57 2.92 2.27 3.75 3.15 6.60 5.53 2.82 2.18 1.52 4.12 3.48 6.07 6.72 7.00 8.30 8.31 7.01 0.32 2.28 3.58 4.88 4.23 2.93 0.32 1.63 0.98 0.00 3.58 2.28 1.62 0.98 2.92 6.99 4.22 5.52 8.29 8.29 8.30 6.00 7.00 5.70 6.20 4.40 4.90 3.10 3.60 1.30 2.30 5.60 4.60 8.30 2.10 8.30 0.90 1.90 3.10 5.10

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