![]() |
|
If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
Datasheet File OCR Text: |
? 2014 microchip technology inc. ds20005333a-page 1 hv9861a features fast average current control programmable constant off-time switching pwm / linear dimming input output short circuit protection with skip mode ambient operating temperature -40c to +125c pin-compatible with the hv9910b and hv9961 applications dc/dc or ac/dc led driver applications led back-light driver for lcd displays general purpose constant current source led signage and displays architectural and decorative led lighting led street lighting description hv9861a is a patented, average-mode, constant-cur- rent control, led driver ic operating in a constant off- time mode. unlike the hv9910b, this control ic does not produce a peak-to-average error, which therefore greatly improves the accuracy, line and load regulation of the led current without any need for loop compen- sation or high-side current sensing. the output led current accuracy is 3%. the ic is equipped with a current limit comparator for hiccup-mode output short circuit protection. internal over-temperature protection is provided. the internally regulated voltage (v dd ) for the hv9861a is 7.5v. the ic can be powered from a 15 - 450v supply. a pwm dimming input is provided that accepts an exter- nal control ttl-compatible signal. the output current can be programmed by an internal 270mv reference, or controlled externally through a 0 - 1.5v dimming input. hv9861a is pin-to-pin compatible with the hv9910b and hv9961, and can be used as a drop-in replace- ment for many applications to improve the led current accuracy and regulation. led driver with average-mode constant current control downloaded from: http:///
hv9861a ds20005333a-page 2 ? 2014 microchip technology inc. package types typical application circuit 8-lead soic 16-lead soic vin cs gnd gate rtld vdd pwmd vin ncnc cs gnd ncnc gate ncnc rt ld vdd nc nc pwmd 12 3 4 5 6 7 8 1615 14 13 12 11 10 9 12 3 4 87 6 5 see ta b l e 2 - 1 for pin information pwmdvdd ld gate cs rt vin hv9861a 15vdc to 450vdc setsled current ledload gnd r cs r t downloaded from: http:/// ? 2014 microchip technology inc. ds20005333a-page 3 hv9861a 1.0 electrical characteristics absolute maximum ratings v in to gnd...................................................... -0.5v to +470v v dd to gnd.......................................................................12v ld, pwmd, gate to gnd................. ....-0.3v to (v dd + 0.3v) cs, rt to gnd .............................................. ....-0.3v to 5.0v operating temperature ..................................-40c to +125c storage temperature .....................................-65c to +150c continuous power dissipation (t a = +25c) 8-lead soic ...............................................650 mw 16-lead soic ...........................................1000 mw note : stresses above those listed under absolute maximum ratings may cause permanent dam age to the device. this is a stress rating only and functional operation of the device at those or any other conditions, above those indicated in the operational listings of this specif ication, is not implied. expo- sure to maximum rating conditions for extended periods may affect device reliability. 1.1 electrical specifications table 1-1: electrical characteristics (sheet 1 of 2) 1 symbol parameter note min typ max units conditions input v indc input dc supply voltage range 2 3 15 - 450 v dc input voltage i insd shut-down mode supply current 3 - 0.5 1.1 ma pin pwmd to gnd internal regulator v dd internally regulated voltage - 7.25 7.50 8.20 v 500pf at gate; rt = 226k ? ? v dd , line line regulation of v dd ---1v v in = 15 - 450v, 500pf at gate; rt = 226k ? ? v dd , load load regulation of v dd ---1 0 0m v i dd(ext) = 0 - 1ma, 500pf at gate; rt = 226k ? uvlo v dd under-voltage lockout threshold 3 6.45 - - v v in rising ? uvlo v dd under-voltage lockout hysteresis --5 0 0-m v v in falling ? v dd(uv) v dd voltage margin 3 500 - - mv ? v dd(uv) = v dd - uvlo i in,max maximum input current (limited by uvlo) 4 3.5 - - ma v in = 15v, t a = 25c 4 1.5 - - v in = 15v, t a = 125c pwm dimming v en(lo) pwmd input low voltage 3 --0 . 8vv in = 15 - 450v v en(hi) pwmd input high voltage 3 2.2 - - v v in = 15 - 450v i en internal pull-down current at pwmd -8 . 5-1 3 . 5 av pwmd = 0.8v downloaded from: http:/// hv9861a ds20005333a-page 4 ? 2014 microchip technology inc. average current sense logic v cs current sense reference voltage - 262 - 280 mv a v(ld) ld-to-cs voltage ratio - 0.175 - 0.182 - a v v ld(offset) ld-to-cs voltage offset - -10 - 10 mv offset = v cs - (a v(ld) v ld ); v ld = 1.2v ? v cs(temp) cs threshold temp regula- tion 4 --5m v v ld(off) ld input voltage, shutdown - - 150 - mv v ld falling ? v ld(off) ld input voltage, enable - - 200 - mv v ld rising t blank current sense blanking interval 3 140 - 290 ns t on(min) minimum on-time - - - 760 ns cs = v cs + 30mv d max maximum steady-state duty cycle 3 80 - - % reduction in output led cur- rent may occur beyond this duty cycle short circuit protection v cs hiccup threshold voltage 3 410 - 510 mv t delay current limit delay cs-to- gate ---1 5 0n sc s = v cs + 30mv t hiccup short circuit hiccup time - 400 - 850 s t on(min) minimum on-time (short circuit) - - - 430 ns cs = 4v toff timer t off off-time -3 24 04 8 s r t = 1m ? - 8 10 12 r t = 226k ? gate driver i source sourcing current - 0.165 - - a v gate = 0v, v dd = 7.5v i sink sinking current - 0.165 - - a v gate = vdd, v dd = 7.5v t rise output rise time - - 30 50 ns c gate = 500pf, v dd = 7.5v t fall output fall time - - 30 50 ns c gate = 500pf, v dd = 7.5v over-temperature protection t sd shut-down temperature 4 128 140 - c --- ? t sd hysteresis 4 - 20 - c --- 1 specifications are t a = 25c, v in = 15v, v ld = v dd , pwmd = v dd unless otherwise noted. 2 also limited by package-power dissipation limit; whichever is lower. 3 applies over the full operating ambient temperature range of -40c < t a < +125c. 4 for design guidance only table 1-1: electrical characteristics (continued) (sheet 2 of 2) 1 symbol parameter note min typ max units conditions table 1-2: thermal resistance package ja 8-lead soic 101c/w 16-lead soic 83c/w downloaded from: http:/// ? 2014 microchip technology inc. ds20005333a-page 5 hv9861a 2.0 pin description the locations of the pins are listed in package types . table 2-1: pin description pin # function description 8-lead soic 16-lead soic 1 1 vin input of a 15 - 450v linear regulator. 24c s current sense pin used to sense the fet current by means of an external sense resistor. 35g n d ground return for all internal circuitry. this pin must be electrically connected to the ground of the power train. 4 8 gate output gate driver for an external n-channel power mosfet. 59p w m d pwm-dimming input of the ic. when this pin is pulled to gnd, the gate driver is turned off. when th e pin is pulled high, the gate driver operates normally. 61 2v d d power supply pin for all internal circuits. it must be bypassed with a low esr capacitor to gnd (at least 0.1 f). 71 3l d linear-dimming input. sets the current sense threshold as long as the voltage at this pin is less than 1.5v. if voltage at ld falls below 150mv, the gate output is disabled. the gate signal recovers at 200mv at ld. 81 4r t a resistor connected between this pin and gnd programs the gate off-time. - 2, 3, 6, 7, 10, 11, 15, 16 nc no connection. downloaded from: http:/// hv9861a ds20005333a-page 6 ? 2014 microchip technology inc. 3.0 application information peak-current control (as in the hv9910b) of a buck converter is the most economical and simple way to regulate its output current. however, this method suf- fers accuracy and regulation problems that arise from the so-called peak-to-average current error, contrib- uted to by the current ripple in the output inductor and the propagation delay in the current-sense comparator. the full inductor-current signal is unavailable for direct sensing at the ground potent ial in a buck converter when the control switch is referenced to the same ground potential. while it is very simple to detect the peak current in the switch, controlling the average inductor current is usually implemented by level trans- lating the sense signal fr om the positive supply rail. though this is practical for relatively low input voltage, this type of average-current control may become excessively complex and expensive in off line ac or other high-voltage dc applications. hv9861a employs a patented control scheme, achiev- ing fast and very accurate control of average current in the buck inductor through sensing the switch current only. no compensation of the current-control loop is required. the led current response to pwmd input is similar to that of the hv991 0b. the inductor-current rip- ple amplitude does not affect this control scheme sig- nificantly. therefore, the led current is independent of the variation in inductance, switching frequency, or out- put voltage. constant off-ti me control of the buck con- verter is used for stability and to improve the led- current regulation over a wi de range of input voltages. (note that, unlike the hv9910b, this ic does not sup- port the constant-freq uency mode of operation.) 3.1 off timer the timing resistor connected to rt determines the off- time of the gate driver, and it must be wired to gnd. wiring this resistor to gate as with the hv9910b is no longer supported. the e quation governing the off-time of the gate output is given by: within the range of 30k ? r t 1.0m ? . 3.2 average current control feedback and output short circuit protection the current through the swit ching mosfet source is averaged and used to give c onstant-current feedback. this current is detected usi ng a sense resistor at the cs pin. the feedback operates in a fast open-loop mode. no compensation is r equired. output current is programmed simply as: when the voltage at the ld input v ld 1.5v. other- wise: the above equations are only valid for continuous con- duction of the output inducto r. it is a good practice to design the inductor such that the switching ripple cur- rent in it is 30~40% of it s average peak-to-peak, full load, dc current. hence, the recommended inductance can be calculated as: the duty-cycle ran ge of the current control feedback is limited to d 0.8. a reduction in the led current may occur when the led string voltage v o is greater than 80% of the input voltage v in of the hv9861a led driver. reducing the output led voltage v o below v o(min) = v in d min , where d min = 760ns/(t off +760ns), may also result in the loss of regulation of the led current. however, this condition causes an increase in the led current and can potentially tr ip the short-circuit protec- tion comparator. a typical output characteristic of the hv9861a led driver is shown in figure 3-1 . the corresponding hv9910b characteristic is given for comparison. figure 3-1: typical output characteristic of an hv9861a led driver t off ? s ?? r t k ? ?? 25 ------------------- - 0.3 + = i led 0.27v r cs --------------- - = i led v ld 0.18 ? r cs ------------------------- = l v omax ?? t off ? 0.4 i o ? ------------------------------------ - = v in = 170vdc hv9861a hv9910b 0 10 20 30 40 50 60 0.60 0.55 0.50 0.45 0.40 0.35 0.30 0.25 led current (a) output voltage (v) output characteristics downloaded from: http:/// ? 2014 microchip technology inc. ds20005333a-page 7 hv9861a the short circuit protection comparator trips when the voltage at cs exceeds 0.45v. when this occurs, the gate off-time t hiccup = 650s is generated to prevent stair-casing of the inductor current, and potentially its saturation, due to insufficient output voltage. the typi- cal short-circuit current is shown in the waveform of figure 3-2 . figure 3-2: short-circuit inductor current a leading-edge blanking delay is provided at cs to pre- vent false triggering of the current feedback and the short circuit protection. 3.3 linear dimming when the voltage at ld falls below 1.5v, the internal 270mv reference to the co nstant-current feedback becomes overridden by v ld 0.18. as long as the cur- rent in the inductor remains continuous, the led cur- rent is given by the equation in section 3.2 . however, when v ld falls below 150mv, the gate output becomes disabled. the gate signal recovers, when v ld exceeds 200mv. this is required in some applica- tions to be able to shut the led lamp off with the same signal input that controls the brightness. the typical lin- ear dimming response is shown in figure 3-3 . figure 3-3: typical linear dimming response of an hv9861a led driver the linear dimming input could also be used for mixed- mode dimming to expand the dimming ratio. in such case a pulse-width modulated signal of a measured amplitude below 1.5v should be applied at ld. 3.4 input voltage regulator hv9861a can be powered directly from a 15 C 450vdc supply through its vin input. when this voltage is applied at the vin pin, the hv9861a maintains a con- stant 7.5v level at vdd. this voltage can be used to power the ic and external circuitry connected to vdd within the rated maximum current or within the thermal ratings of the package, whic hever limit is lower. the vdd pin must be bypassed by a low esr capacitor to provide a low impedance path for the high frequency current of the ga te output. the hv9861a can also be powered through the vdd pin directly with a voltage greater than the internally regulated 7.5v, but less than 12v. despite the instantaneous voltage rating of 450v, con- tinuous voltage at vin is limited by the power dissipa- tion in the package. for example, when these ics draw i in = 3.0ma from the vin i nput, and the 8-lead soic package is used, the maximum continuous voltage at vin is limited to the following: in this instance, the ambient temperature t a = 25c, the maximum working junction temperature t j(max) = 125c, and the junction-to-ambient thermal resistance r ,ja = 101c/w. in such cases, when it is needed to operate the hv9861a from a higher voltage, a resistor or a zener diode can be added in series with the vin input to divert some of the power loss from the ic. in the above exam- ple, using a 100v zener diode will allow the circuit to work up to 430v. the input current drawn from the vin pin is represented by the following equation: in the above equation, f s is the switching frequency, and q g is the gate charge of the external fet obtained from the manufacturers data sheet. 3.5 gate output the gate output of hv9861a is used to drive an exter- nal mosfet. the gate charge, q g , of the external mosfet should be less than 25nc for switching fre- quencies 100khz and less than 15nc for switching frequencies >100khz. 650s 0.45v/r cs 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0 led current (a) ld (v) ld response characteristics v in max ?? t jmax ?? t a C r ? ja C ? i in ? ------------------------------ - 330v == i in 1.0ma q g f s ? + ? downloaded from: http:/// hv9861a ds20005333a-page 8 ? 2014 microchip technology inc. 3.6 pwm dimming due to the fast open-loop response of the average- mode, current-control loop of the hv9861a, the pwm dimming performance nearly matches that of the hv9910b. the inductor current waveform comparison is shown in figure 3-4 . figure 3-4: typical pwm dimming response of an hv9861a led driver the rising and falling edges are limited by the current slew rate in the inductor. the first switching cycle is ter- minated upon reaching the 270mv (v ld 0.18) level at cs. the circuit is further reaching its steady-state within 3C4 switching cycles regardless of the switching frequency. figure 3-5: functio nal block diagram ch2 (red): pwmd ch4 (green): inductor current ch3 (blue): same as hv9910b, for comparison r qs q t off timer latch enable blanking 0.45v min (v ld ? 0.18, 0.27v) 650s current mirror i regulator vin ld cs gnd vdd gate pwmd rt uvlo por 0.15/0.20v average current control logic out auto-ref hv9861a clk in + - + - + - 11a downloaded from: http:/// ? 2014 microchip technology inc. ds20005333a-page 9 hv9861a 4.0 packaging information 4.1 package marking information legend: xx...x product code or cust omer-specific information y year code (last digit of calendar year) yy year code (last 2 digits of calendar year) ww week code (week of january 1 is week 01) nnn alphanumeric traceability code pb-free jedec ? designator for matte tin (sn) * this package is pb-free. the pb -free jedec designator ( ) can be found on the outer packaging for this package. note : in the event the full microchip part num ber cannot be marked on one line, it will be carried over to the next line, t hus limiting the number of available characters for product code or customer-specific information. package may or not include the corporate logo. 8-lead soic example nnn xx xxxxxxxx yyww e 3 343 lg hv9861a 1447 e 3 16-lead soic xxxxxxxxx xxxxxxxxxxx yywwnnn e 3 example hv9861ang1447343 e 3 downloaded from: http:/// hv9861a ds20005333a-page 10 ? 2014 microchip technology inc. note: for the most current package drawings, see the microchip packaging specification at www.microchip.com/packaging. downloaded from: http:/// ? 2014 microchip technology inc. ds20005333a-page 11 hv9861a 16-lead soic (narrow body) package outline (ng) 9.90x3.90mm body, 1.75mm height (max), 1.27mm pitch symbol a a1 a2 b d e e1 e h l l1 l2 dimension (mm) min 1.35* 0.10 1.25 0.31 9.80* 5.80* 3.80* 1.27 bsc 0.25 0.40 1.04 ref 0.25 bsc 0 o 5 o nom - - - - 9.90 6.00 3.90 - - - - max 1.75 0.25 1.65* 0.51 10.00* 6.20* 4.00* 0.50 1.27 8 o 15 o jedec registration ms-012, variation ac, issue e, sept. 2005. 7 k l v g l p h q v l r q l v q r w v s h f l ? h g l q w k h - ( ' ( & |