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fn6531 rev 1.00 page 1 of 14 august 12, 2015 fn6531 rev 1.00 august 12, 2015 isl9491, isl9491a single output lnb supply voltage regulator for satellite set-to p box applications datasheet these devices are designed for supplying power and control signals from advanced satellite set-top box (stb) modules to the low noise blocks (lnbs) of single antenna ports. each device consists of a current-mode boost converter and a low-noise linear regulator along with the circuitry required for tone injection and pin controllable interface. the device makes the total lnb supply design simple, efficient and compact with low external component count. the current-mode boost converters provide the linear regulator with input voltage that is set to the voltage at the vout pin plus a minimal drop to insure minimum power dissipation across the internal ldo. this maintains constant voltage drop across the linear pass element while permitting adequate voltage range for tone injection. the final regulated output voltage is available at the cathode of the back diode to support the operation of an antenna port for a single tuner. the outputs can be set to various voltage level for the desired polarization reception by means of the logic presented to the vset0 and vset1 pins. an en pin is to be driven high to enable the outputs for the pwm and linear combination; setting en low disables the output, forcing a shutdown mode. the external modulation input (extm) can accept a tone modulated diseqc command and transfer it symmetrically to the output to meet diseqc 1.x protocol. an external diseqc tank circuit can also be implemented to support diseqc 2.x. features ? single chip power solution - operation for 1-tuner/1-dish applications ? switch-mode power converter for lowest dissipation - boost pwms with >92% efficiency - pin controllable enable and output ? 2.5v/3.3v/5v logic compatible ?fault signal ?directv swm compliant ? vset pin to toggle between vertical and horizontal polarizations ?external tone input ? internal overcurrent and over-temperature protection ? pb-free (rohs compliant) applications ? lnb power supply and control for satellite set-top box pin configuration isl9491, isl9491a (16 ld qfn) top view ordering information part number (note) part marking temp. range (c) package (pb-free) pkg. dwg. # isl9491erz* 94 91erz -20 to +85 16 ld qfn l16.4x4 ISL9491AERZ* (no longer available or supported) 94 91aerz -20 to +85 16 ld qfn l16.4x4 *add ?-t? suffix for tape and reel. please refer to tb347 for details on reel specifications. note: these intersil pb-free plas tic packaged products employ special pb-free material sets, molding compounds/die attach materials, and 100% matte tin plate plus anneal (e3 termination finish, which is rohs compliant and compatible with both snpb and pb-free solderin g operations). intersil pb-free products are msl classified at pb -free peak reflow temperatures that meet or exceed the pb-free requirements of ipc/jedec j std-020. 1 3 4 15 vcc cs pgnd gate extm en vsw fault 16 14 13 2 12 10 9 11 6 578 ilimit tcap vset1 vset0 bypass vout vsense sgnd
isl9491, isl9491a fn6531 rev 1.00 page 2 of 14 august 12, 2015 functional pin description symbol function vsw input of the linear post-regulator. pgnd dedicated ground for the output gate driver of respective pwm. cs current sense input; conne ct the sense resistor r sc at this pin for desired peak overcurrent value for the boost fet. sgnd small signal ground for the ic. tcap capacitor for setting rise and fall time of the output voltage. typical value is 0.1f. bypass connect a bypass capacito r of 1f for the internal 5v. vcc main power supply to the chip. gate this pin connects to the gate of the boost fet. vout output voltage for the lnb meant to be connected to th e anode of a back diode in series with the lnb output. vsense this pin provides for a sensing and pull-down function for the vlnb and is meant to be connected to the cathode of the back diode. extm this is an input for externally modulated diseqc tone sign al, which is transferred symmetrically onto vlnb. vset0, vset1 output voltage selection pins. en when this pin is low, the output is disabled in a low power standby state. setting en = 1 enables the output voltage. fault this an open drain output to be pulled up to the logi c high through a resistor. a low indicates that the output voltage is out of regulation. ilimit the ilimit is used to set the value of the output cu rrent limit from the linear. a resistor from ilimit to gnd programs this limit.
isl9491, isl9491a fn6531 rev 1.00 page 3 of 14 august 12, 2015 block diagram counter overcurrent protection logic scheme 1 olf dcl oc1 clk1 pwm logic q s gate pgnd cs cs amp ilim1 slope compensation ? 16 4 2 11 7 1 vsense vcc sgnd bypass extm thermal shutdown otf oscillator band gap ref voltage adj1 ref voltage tone shape/inj ckt tcap + - en soft-start int 5v on chip ldo uvlo por soft-start 8 14 vsw + - bgv 5 vref1 + - vset1 3 10 vref2 en vset0 9 15 fault 13 ilimit 12 drive u and l fet 6 vout
fn6531 rev 1.00 page 4 of 14 august 12, 2015 isl9491, isl9491a typical application schematic qfn l8 10h c36 56f d9 b230a c35 100f c31 10f 1 2 0 + + 0 0 1 2 3 6 5 4 r18 18 ? 0 0 1 2 3 4 c37 1f tpc6002 q1 r17 470 ? r16 0.100 ? c34 100pf 1f c39 5 6 7 8 12 11 10 9 16 15 14 13 0 0 0 0.22f c40 r21 91.1k ? r20 10k ? r19 3.3k ? c42 0.1f 0 0 d12 b230a vbypass 3.3/5v d11 b230a vin rtn extm en fault vset1 vset0 vlnb rtn d10 1.5smc22a vset1 vset0 pgnd gate cs vcc tcap ilimit bypass vout vsense sgnd extm en vsw fault u1 isl9491er, or notes: 1. the output voltage level for the desired polarization reception can be selected by means of th e logic presente d to vset0 and vset1 pins. isl9491aer r22 15 ? 220h l2 c41 0.1f diseqc r23 10k ? fet on
isl9491, isl9491a fn6531 rev 1.00 page 5 of 14 august 12, 2015 absolute maximum ratings thermal information vcc (input voltage) . . . . . . . . . . . . . . . . . . 8.0v to 18.0v vout, vsw . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 24v bypass . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 5.5v en, vset0/1, extm (logic control pins) . . . . . -0.3v to 5.5v all pins referenced to ground thermal resistance (typical) ? ja (c/w) ? jc (c/w) qfn package (notes 2, 3) . . . . . . . 47 9.5 maximum junction temperature (note 4) . . . . . . . +150c maximum storage temperature range . . . -40c to +150c pb-free reflow profile . . . . . . . . . . . . . . . . . .see link below http://www.intersil.com/pbfree/pb-freereflow.asp recommended operating conditions temperature. . . . . . . . . . . . . . . . . . . . . . . -20c 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: 2. ? ja is me asu red in fre e air with t he com pon ent mounted on a high effective thermal conductivity test board with ?direct attach? features. see tech brief tb379. 3. for ? jc , the "case temp" location is the center of the exposed metal pad on the package underside. 4. the device junction temperature should be kept below +150c. thermal shut-down circuitry turns off the device if junction temperature exceeds +130c typical. electrical specifications v cc = 12v, t a = -20c to +85c, unless otherwise noted. typical values are at t a = +25c. parameter symbol test conditions min typ max units operating supply voltage range isl9491 8 12 14 v isl9491a 8 10 11 v supply current (ivcc current) i in en = 1, boost disconnected, and ext. 14.5v supply on vsw when v out = 13.3v, no load -48ma undervoltage lockout stop threshold input voltage falling from above 8v - 4.4 - v start threshold input voltage rising from 0v - 4.9 - v output voltage, isl9491 v o en = 1, vset1 = 0, vset0 = 0 12.8 13.3 13.6 v en = 1, vset1 = 0, vset0 = 1 17.7 18.3 18.7 v en = 1, vset1 = 1, vset0 = 0 13.8 14.3 14.6 v en = 1, vset1 = 1, vset0 = 1 19.4 20.0 20.4 v output voltage, isl9491a v o en = 1, vset1 = 0, vset0 = 0 10.5 11.0 11.3 v en = 1, vset1 = 0, vset0 = 1 14.5 15.0 15.3 v en = 1, vset1 = 1, vset0 = 0 11.5 12.0 12.3 v en = 1, vset1 = 1, vset0 = 1 15.5 16.0 16.3 v line regulation dv o1, dv o2 v in = 8v to 14v; v o = 13.30v - 4 40 mv v in = 8v to 14v; v o = 18.30v - 4 60 mv load regulation dv o1, dv o2 i o = 0ma to 350ma, v out = 13.3v - 125 180 mv i o = 0ma to 500ma, v out = 13.3v (note 4) -190260mv output overcurrent threshold i oct r at i limit = 148k (note 8) 270 350 435 ma internal regulator overcurrent clamp i oclmp output shorted to gnd, r ilim = 0 860 ma
isl9491, isl9491a fn6531 rev 1.00 page 6 of 14 august 12, 2015 dynamic overload protection off-time t off output shorted to gnd (note 6) - 900 - ms dynamic overload protection on-time t on -50-ms tcap charging current tcap c tcap pin = 0v - 22 - a tcap discharging current tcap d tcap pin = 2v - 21 - a linear regulator drop-out voltage i out = 500ma, with a schottky b/w vsw and v out (note 4) -1.21.4v output backward leakage current i bklk en = 0; v obk = 24v (note 9) - 2.0 3.0 ma output undervoltage (after initial power-up ) fault asserted for typical v out = 13.3v -12 - -1 % output overvoltage (after initial power-up) fault asserted for typical v out = 13.3v +1 - +12 % en, vset, extm input pins (note 5) asserted low --0.8v asserted high 2.5 - - v input current -25-a tone input frequency isl9491 extm input 22 khz isl9491a extm input 44 khz v out tone amplitude isl9491 extm input = 22khz square wave vmax = 2.5v, vmin = 0v, duty = 50%, 400 650 900 mv isl9491a extm input = 44khz square wave vmax = 2.5v, vmin = 0v, duty = 50% 400 650 900 mv v out tone rise (note 10) isl9491 extm input = 22khz square wave vhmax = 2.5v, vlmin = 0v, r l = 1k 51015s isl9491a extm input = 44khz square wave vhmax = 2.5v, vlmin = 0v, r l = 1k 468s v out tone fall (note 10) isl9491 extm input = 22khz square wave vhmax = 2.5v, vlmin = 0v, duty = 50%, r l = 1k 51015s isl9491a extm input = 44khz square wave vhmax = 2.5v, vlmin = 0v, duty = 50%, r l = 1k 468s current sense (cs pin) overcurrent threshold v cs 380 445 510 mv bypass voltage at bypass pin v bypass (note 7) - 5 - v pwm maximum duty cycle 90 93 - % minimum pulse width -20-ns electrical specifications v cc = 12v, t a = -20c to +85c, unless otherwise noted. typical values are at t a = +25c. (continued) parameter symbol test conditions min typ max units
isl9491, isl9491a fn6531 rev 1.00 page 7 of 14 august 12, 2015 oscillator oscillator frequency f sw boost switching frequency 380 440 480 khz thermal shutdown temperature shutdown threshold (note 4) - 130 - c temperature shutdown hysteresis (note 4) - 20 - c 5. vset, extm, en pins have 200k ? internal pull-down resistors. 6. in the dynamic current limit mode, the output is on for 50ms and off for 900ms but it remains continuously on when rilim=0. 7. this pin is to connect a bypass capacitor in order to decouple the internal ld o and is not designed to source external circui ts. 8. the value of the r limit resistor will determine the overcurrent threshold at which the 50ms timer is activated. 9. this defines the back voltage applicable to the vsense pin. the vout pin will not support back bias and hence will need the use of a back diode for protection. electrical specifications v cc = 12v, t a = -20c to +85c, unless otherwise noted. typical values are at t a = +25c. (continued) parameter symbol test conditions min typ max units tone waveform notes: 10. the tone rise and fall times are not shown due to resolution of graphics. it is 5/10s typical. 11. the extm pins have input thresholds of vil(max) = 0.8v and vih(min) = 2.5v figure 1. tone waveform extm vout 22khz 22khz pin pin returns to nominal vout ~1.5 period after the last extm rising edge t_isl9491~68s / t_isl9491a)~34s external tone t r = 5/10s typical typical performance curves figure 2. boost efficiency for 12v in to 14.3v out figure 3. system efficiency (boost + ldo) for 12v in to 13.3v out 0 20 40 60 80 100 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 i load (a) efficiency (%) 0 20 40 60 80 100 0 0.10.20.30.40.50.6 i load (a) efficiency (%)
isl9491, isl9491a fn6531 rev 1.00 page 8 of 14 august 12, 2015 figure 4. vlnb rise time with tcap = 0.22f is 13ms figure 5. vlnb rise time with tcap = 0.44f is 32ms figure 6. boost switch node at 0a (discontinuous) figure 7. boost switch node at 100ma (partial continuous) figure 8. boost switch node at 300ma (continuous mode) figure 9. vlbnb transitions from 13.3v to 18.3v typical performance curves (continued)
isl9491, isl9491a fn6531 rev 1.00 page 9 of 14 august 12, 2015 figure 10. vlnb transitions from 18.3v to 13.3v figure 11. 22khz tone on 13.3v out with 50ma load figure 12. 22khz tone on 13.3v out with 500ma load figure 13. ac noise on 13.3v out at 500ma of load figure 14. vlnb connected to 350ma load with r ilim = 148k figure 15. vlnb shorted to gnd, 200ma 2 typical performance curves (continued) load current vlnb output current output voltage
isl9491, isl9491a fn6531 rev 1.00 page 10 of 14 august 12, 2015 \ figure 16. output current and voltage with output shorted to gnd, r ilim =0 figure 17. the isl9491 entering thermal shutdown with r ilim = 0 figure 18. the isl9491 in thermal equilibrium with r ilim = 0 typical performance curves (continued) output current output voltage
isl9491, isl9491a fn6531 rev 1.00 page 11 of 14 august 12, 2015 functional description the isl9491 or isl9491a single output voltage regulator makes an ideal choice for advanced satellite set-top box and personal video recorder applications. the device utilizes built-in dc/dc step-up converters, which operate from a single supply source ranging from 8v to 14v and generate the voltage needed to enable the linear post-regulator to work with minimum dissipated power. an undervoltage lockout circuit disables the device when vcc drops below a fixed threshold (4.5v typical). diseqc encoding the extm accepts an externally modulated tone command and in turn modulates the v lnb symmetrically to meet the diseqc 1.0 and diseqc 2.0 transmit protocol. burst coding of the tone can be accomplished due to the fast response of the extm pin. linear regulator the output linear regulator is designed to source 500ma continuous current and 750ma peak. the sink feature is limited and thus requires a bleeder resistor of 3.3k ? to be connected at the vlnb to enable proper tone modulation capability into capacitive loads as high as 0.22f. in order to minimize the power dissipation, the output voltage of the internal step-up converter is adjusted to allow the linear regulator to work at a minimum dropout of 1.2v typical (load current = 500ma) between the vsw and vout pin. the vout pin drives the anode of the back diode and the vsense pin drives the cathode of the back diode. the vsense pin is capable of withstanding a back voltage of 24v. when the device is put in the shutdown mode (en = low), the pwm power block is disabled. when the regulator blocks are active (en = high), the output can be controlled by the vset0 and vset1 pins to be 13.3v, 14.3v, 18.3v or 20v (typical isl9491) or 11v, 12v, 15v, or 16v (typical isl9491a) fo r remote controlling of non- diseqc lnbs. a separate open-drain fault pin serves as an interrupt and is driven low by undervoltage, overvoltage and linear overcurrent and over-temperature faults. output voltage rise and fall timetiming the output voltage rise and fall times or soft-start time can be set by an the external capacitor on the tcap pin. the output rise and fall times are given by equation 1: where c is the tcap value in nf, t rise the required transition time in ms and ? v is the differential transition voltage from low output voltage range to the high output range in volts. too large a value of tcap prevents the output from rising to the nominal value, within a reasonable time. too small a value of the tcap can cause high peak currents in the boost circuit. figures 4 and 5 show the output voltage rise time for tcap value of 0.22f and 0.44f as 13.6ms and 32ms which according to equation 1 should be 13.3ms and 26.6ms. the difference between measured and calculated values is due to capacitor tolerance of 20%. since the output voltage uses tcap voltage as a reference, it is recommended to use a 10k ? resistor in series to filter out some of the switching noise from injecting on this pin. dynamic and static current limiting when the ldo current exceeds the preset overcurrent threshold set by means of a resistor from the ilimit pin to gnd for a period of 50m s, the device enters a t on =50ms/t off = 900ms routine. this type of current limiting is also called ?dynamic current limiting?, which is used extensively on other intersil lnb controllers. a linear overcurrent will drive the fault pin low during the t off = 900ms period. this operation continues until the fault is removed. upon removal of the fault, the device returns to normal operation after a successful soft-start cycle. figure 14 shows the output current and voltage waveforms with an i limit resistor of 148k ? and a load current of 350ma. it can be seen that under this loading condition, the chip stays powered up and sources load current for 50ms and turns-of f for approximately 900ms. the output voltage ramps up to programmed output voltage during the on time.this cycle repeats itself until load current is reduced below the current limit value of 350ma. equation 2 shows the relationship between ilimit resistor and load current: i limit is the programmed load current in ma before the chip goes into current limit where r ilimit is in k ???? alpha ( ? ) is a gain term which is shown in figure 19 and has a value of one at 350ma. it is a good design practice to use a 1% tolerance resistor and allow for at least 20% higher margin on the maximum load current when calculating the r ilimit resistor value. figure 15 shows the output current and voltage for r ilimit =148k ? when the output voltage is shorted to gnd. under this condition, the chip still exhibits the 50ms on and 900ms off pulse to minimize power dissipation, however, current gets internally clamped to approximately 750ma. the output voltage stays at 0v c 220t rise ? v -------------------- - = (eq. 1) ilimit 52 000 ? ? r ilimit -------------------- - ? = (eq. 2) 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 100 150 200 250 300 350 400 450 500 550 i limit (ma) figure 19. alpha constant alpha ( ? )
fn6531 rev 1.00 page 12 of 14 august 12, 2015 isl9491, isl9491a intersil products are manufactured, assembled and tested utilizing iso9001 quality systems as noted in the quality certifications found at www.intersil.com/en/suppor t/qualandreliability.html intersil products are sold by description on ly. intersil may modify the circuit design an d/or specifications of products at any time without notice, provided that such modification does not, in intersil's sole judgment, affect the form, fit or function of the product. accordingly, the reader is cautioned to verify that datasheets are current before placing orders. information fu rnished by intersil is believed to be accu rate and reliable. however, no responsib ility is assumed by intersil or its subsidiaries for its use; nor for any infrin gements of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of intersil or its subsidiaries. for information regarding intersil corporation and its products, see www.intersil.com for additional products, see www.intersil.com/en/products.html ? copyright intersil americas llc 2009-2015. all rights reserved. all trademarks and registered trademarks are the property of their respective owners. due to hard short on the output. the current limiting described so far is called ?dynamic current? limiting which limits current to approximately 750ma for 50ms and turns off the output for 900ms. r ilim is used to program the current level at which the isl9491 enters into this protection mode. on the other hand, the isl9491 can also be programmed in ?static current limit? mode which defeats the 50ms/900ms(on/off) pulse by delivering constant 750ma load current to the system by using a 0 ? r ilimit resistor. in this mode the chip will deliver this current to the load for as long as the die junction temperature is less than 130 o c. figure 16 shows the static current limit by shorting the output to gnd. it also shows that initially the chip delivers 750ma but the junction starts heating up since approximately 10w (13.3v*0.75a) is being dissipated internally. the thermal shutdown circuitry takes over and shuts the output ldo stage-off after approximately 50ms and the load current drops to zero as seen in figure 17. the chip restarts as soon as the junction temperature drops below the thermal shutdown level but quickly shuts off in 15ms as seen in figure 18. the cs pin provides peak curre nt protection for the boost fet on a pulse-by-pulse basis. once the voltage on the fet source sense resistor crosses 0.45v typical, the boost fet drive is set to low. the sense resistor can be sized to limit the peak current through the fet. it is highly recommended to have a boost current limit of 200% when sizing the sense resistor to accommodate high current transients in the boost circuit. thermal protection this ic is protected against overheating. when the junction temperature exceeds +130c (typical), the step-up converter and the linear regulator are shut-off. when the junction is cooled down to +110c (typical), normal operation is resumed. external output voltage selection the pin vset0 and vset1 are provided for switching between typical output voltages, as indicated in table 1. output over/undervoltage fault and extm the recommended start-up sequence is vcc going high followed by enable while ex tm is pulled low. this will start the output voltage to ramp up with a dv/dt which is based on the tcap value. once enable is pulled high, allow a 50ms delay before applying 22khz/44khz, 50% square pulse on extm pin to generate the diseq tone on the output. at this point, fault should also be high, indicating that output voltage is in regulation. fault is designed to stay high when the output voltage is commanded to transition between the values listed in table 1, and also when passing the diseq tone on the output. fault will immediately pull low if there is a short on the output or if the voltage falls outside the 10% window indicating that the voltage is out of regulation. fault signal is armed after the first initial power-up when output voltage is in steady-state. if tone is applied to the extm pin before the chip is enabled, it causes the fault to remain low even after the output voltage reaches steady state. this issue can be resolved by pulling the extm low for 2 cycles which is 90ms of isl9491 and 45ms for isl9491a. table 1. en vset1 vset0 vlnb isl9491 vlnb isl9491a 0 x x disabled disabled 1 0 0 13.3v 11.0v 1 0 1 18.3v 15.0v 1 1 0 14.3v 12.0v 1 1 1 20.0v 16.0v
isl9491, isl9491a fn6531 rev 1.00 page 13 of 14 august 12, 2015 about intersil intersil corporation is a leading provider of innovative power management and precision analog solutions. the company's products address some of the largest markets wi thin the industrial and infr astructure, mobile computing and high-end consumer markets. for the most updated datasheet, application notes, related document ation and related parts, please see the respective product information page found at www.intersil.com . you may report errors or suggestions for improving this datasheet by visiting www.intersil.com/ask . reliability reports are also available from our website at www.intersil.com/support revision history the revision history provided is for informational purposes only and is believed to be accurate, but not warranted. please go t o the web to make sure that yo u have the latest revision. date revision change august 12, 2015 fn6531.1 updated orde ring information table on page 1. added revision history and about intersil sections.
isl9491, isl9491a fn6531 rev 1.00 page 14 of 14 august 12, 2015 package outline drawing l16.4x4 16 lead quad flat no-lead plastic package rev 6, 02/08 located within the zone indicated. the pin #1 identifier may be unless otherwise specified, tolerance : decimal 0.05 tiebar shown (if present) is a non-functional feature. the configuration of the pin #1 identifier is optional, but mus t be between 0.15mm and 0.30mm from the terminal tip. dimension b applies to the metallized terminal and is measured dimensions in ( ) for reference only. dimensioning and tolerancing conform to amse y14.5m-1994. 6. either a mold or mark feature. 3. 5. 4. 2. dimensions are in millimeters. 1. notes: bottom view detail "x" side view typical recommended land pattern top view index area (4x) 0.15 pin 1 6 4.00 4.00 a b +0.15 -0.10 16x 0 . 60 2 . 10 0 . 15 0.28 +0.07 / -0.05 pin #1 index area 5 8 4 0.10 c m 12 9 4 0.65 12x 13 4x 1.95 16 1 6 a b ( 3 . 6 typ ) ( 2 . 10 ) ( 12x 0 . 65 ) ( 16x 0 . 28 ) ( 16 x 0 . 8 ) see detail "x" base plane 1.00 max 0 . 2 ref 0 . 00 min. 0 . 05 max. c 5 0.08 c c seating plane 0.10 c

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