View HT7963_9061186.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

rev. 1.00 1 august 14, 2015 rev. 1.00 pb august 14, 2015 HT7963 led backlight driver features ? integrated high power boost dc-dc controller ? wide input voltage range from 9v to 30v ? high voltage gate-drive provides lower r ds(on) and higher effciencies ? dimming frequency from 100hz to 1khz ? 0.3v led feedback current sensing voltage with 3% tolerance ? device protection features include: soft-start, ocp, uvlo, ovp, otp and output short protection C osp ? led protection: led open/short protection ? package type: 8-pin sop applications ? led backlighting for lcd tv/monitor ? led lighting general description the HT7963 is a high effciency boost converter with a fxed oscillator frequency for led backlighting and led lighting application. the white led current is setup using an external current setting resistor, which has a low feed-back voltage of only 0.3v. the dim input allows a wide range of dimming control for led backlighting or led lighting. the device offers a full range of protection functions such as power mosfet over current protection (ocp), ic power supply under voltage lockout (uvlo), over-voltage protection (ovp), output voltage short circuit protection (osp) and over temperature protection (otp). typical application circuit dim gnd cs ovp drv fb comp vin 1 8 6 3 2 4 7 5 HT7963 vin = 12v~24v 220uf l 47uh c in r c 47k ? r cs d1 47uf c out r fb vout optional r1 100 ? 470pf c fb optional 100 ? 51 ? 0.1uf c c 33nf 10k ? 10pf pwm 0.3v i led = r fb r2 note: the v out /v in ratio is suggested to be lower than 5 to gain better dimming linearity.
rev. 1.00 2 august 14, 2015 HT7963 block diagram osc vref otp control logic ea pwm comparator pre-driver slope compensation comp cs ovp gnd soft-start dim drv 0.1v dimming control fb vin gnd vin gnd clamped to 13v ovp ovp osp osp 6v/8.5v idim ocp idim uvlo 0.5v uvlo ocp leb 1.2v led short led short 0.3v 1.938v pin assignment dim ovp comp fb vin drv gnd cs HT7963 8 sop-a 1 2 3 4 8 7 6 5 pin description pin order name type pin discription 1 vin p power supply 2 drv o boost converter gate drive output 3 gnd g ground terminal 4 cs i boost converter current sense input 5 fb i led current feedback input 6 comp i/o boost converter loop compensation 7 ovp i over voltage protection input C setup using resistor divider 8 dim i external pwm dimming control / enable control absolute maximum ratings parameter value unit vin, drv, cs, fb and ovp -0.3 to 33 v gnd +/-0.3 v dim and comp -0.3 to +7.0 v operating temperature range -40 to +85 c maximum junction temperature +160 c
rev. 1.00 3 august 14, 2015 HT7963 recommended operating range parameter value unit vin 9~30 v cs, ovp and fb 30 v drv (internal voltage clamped) 13 v dim and comp 0~5.5 v dimming frequency dc to 1000 hz dimming duty cycle 1 to 100 % operating junction temperature 125 c note that absolute maximum ratings indicate limitations beyond which damage to the device may occur. recommended operating ratings indicate conditions for which the device is intended to be functional, but do not guarantee specifed performance limits. electrical characteristics v in =12v and ta=25 ? c, unless otherwise specifed symbol parameter test condition min. typ. max. unit supply voltage v in input voltage vin 9 30 v i cc1 operating current dim=5v 2.5 3 ma i cc2 standby current dim=0v 500 650 a i shd shutdown current dim=0v, over 50ms 35 50 a dimming v dim_lh dim high threshold vin=9v to 30v 2.4 v v dim_hl dim low threshold vin=9v to 30v 0.6 v r pd_dim dim internal pull down resistance 500 k f dim dimming frequency dim pin 100 1000 hz f duty dimming duty cycle dim pin 0 100 % t shd shutdown mode entry period dim=0v (figure1) 50 ms t rt recovery time from shutdown mode dim from "l" to "h" (figure1) 30 ms boost converter f sw switching frequency 175 200 225 khz d max maximum duty cycle 95 97.5 % v drv(clamp) drv clamp voltage vin=24v 13 14.5 v t r_drv drv ris e time c=0.5nf 40 ns t f_drv drv falling time c=0.5nf 20 ns t leb leb time of current sense lead-edge blanking 200 ns protections sr ss soft start slope ss 200 mv/ms v ovp output over voltage detect threshold v ovp 1.938 v err ovp tolerance of v ovp -5.0 +5.0 % v uvlo+ input supply turn on level uvlo (on) 8.5 v v uvloC input supply turn off level uvlo (off) 6 v v osp output short circuit threshold osp 0.05 0.1 v v ocp over current protection threshold ocp, v(cs) 0.5 0.65 v v short led short protection threshold led short, v(fb) 1.2 1.56 v v short_hys led short protection hysteresis 70 mv th shd thermal shutdown otp 150 c
rev. 1.00 4 august 14, 2015 HT7963 symbol parameter test condition min. typ. max. unit th shd_hys hysteretic temperature 30 c led output current v fb current feedback sensing voltage vfb 0.3 v err fb tolerance of vfb -3.0 +3.0 % dim iout 50ms, t shd shutdowm mode 30ms t rt figure1 functional description general operation the device is an led driver operating as a dc- dc boost converter in a constant frequency mode. it implements a peak current mode control and has an internal amplifer to accurately control the output current over conditions of wide input voltage and varying load. soft start C ss the device has dedicated protection circuitry running during normal operation. the soft start function is set to have an internal time of around 5ms and is used to prevent a large inrush current during the power-on period. output gate drive stage a cmos buffer output stage is included to drive a power mosfet directly. the output voltage is clamped at 13v to protect the mosfet gate even when the vcc voltage is higher than 13v. input under voltage lockout C uvlo the device contains an i nput u nder -v oltage l ockout circuit. the purpose of the uvlo circuit is to ensure that the input voltage is high enough for reliable op - eration. when the input voltage falls below the under voltage threshold, the external fet switch is switched off. if the input voltage rises beyond the under volt- beyond the under volt- the under volt - age lockout hysteresis value , the device will restart. the uvlo threshold is set below the minimum input voltage of 6v to avoid any transient vin drops under the uvlo threshold which may cause the converter to switch off. current limiting the device has a cycle-by-cycle current limit to protect the ex ternal power mos fet . if the inductor current reaches the current limit threshold , which is when the cs pin voltage is greater than 0.5v , the external mos fet will be switched off. t he r cs value can be calculated from the following formula: i limit = 0.5v r cs dimming control the led brightness control is implemented using a pwm signal on the dim pin. the pwm duty cycle is proportional to the dimming value. the device can apply an external pwm signal on the dim pin with a frequency range from 100hz to 1khz with the required high/low ratio. output over voltage protection C ovp the device includes an over-voltage protection func- includes an over-voltage protection func- an over-voltage protection func- over-voltage protection func- over-voltage protection func - tion. in abnormal condition s , the output voltage may exceed its maximum voltage rating, possibly damag - ing external components and the led s . p rotection circuitry turns off the power mos fet and shuts down the device as soon as the output voltage exceeds the v ovp threshold. as a result, the output voltage falls to the level of the input supply voltage. the device remains in the shutdown mode until the power is re- the shutdown mode until the power is re- shutdown mode until the power is re - cycled. the v out_ovp value can be calculated from the following formula: v out_ovp = 1.938v r 1 +r 2 r 2 output short protection C osp an output short condition is detected by the voltage on pin ovp. in the period during the fault, if the voltage on the ovp pin drops by less than a threshold of around 0.1v, then the output short protection will be activated and the power mosfet will be switched off.
rev. 1.00 5 august 14, 2015 HT7963 thermal shutdown a thermal shutdown function is implemented to prevent damage due to excessive heat and power dissipation. typically the thermal shutdown threshold is 150c. when the thermal shutdown is triggered the device stops switching until the temperature falls below a typical temperature of 125c, after which the device will again begin operation. component selection guide inductor the selected inductor should have a saturation current that meets the maximum peak current of the converter. another important inductor parameter is the dc resistance. lower dc resistance values results in higher converter efficiencies. for most applications, the inductor value can be obtained as below. l = v in (v out - v in ) ?i l f sw v out a higher value of ripple current reduces the induc - tance value, but increases the conductance loss, core loss and current stress for the inductor and switch ing devices. a suggested choice is for the inductor ripple current to be 30% of the maximum load current. this requires that the inductor saturation current be above i l(peak) . i in(max) = v out i out(max) v in ?i l = 30% i in(max) i l(peak) = i in(max) + 1 2 ?i l i out(max) is the maximum load current, i l is the peak- to-peak inductor ripple current, is the converter ef - fciency, f sw is the switching frequency and i l(peak) is the peak inductor current. schottky diode it is recommended to use a schottky diode with low forward voltage to minimise the power dissipation and therefore to maximise the converter efficiency. the breakdown voltage rating of the diode should be higher than the maximum output voltage. the average and peak current rating must be greater than the maximum output current and peak inductor current to ensure the best reliability in most applications. mosfet it is recommended to use a mosfet with small on resistance to minimise the power dissipation and there- s e the power dissipation and there- e the power dissipation and there- dissipation and there- dissipation and there - fore to maximi s e the converter effciency. mosfets with small gate capacitance values need to be selected to have high-speed switching. the maximum voltage rating of the mosfet should be higher than the sum of v out and the rectifying diode v f . the maximum current rating must be greater than the over current protection setting and peak inductor current to ensure the best reliability in most applications. input capacitor a low esr ceramic capacitor is required to be connected between the vin and gnd pins. use ceramic capacitors with x5r or x7r dielectrics for their low esrs and small temperature coefficients. this capacitor must be connected very close to the vin pin and the inductor with short traces for good noise performance. output capacitor a low esr ceramic capacitor is suggested for use here as it will result in lower output ripple voltages. the selection of output capacitor is driven by the maximum allowable output voltage ripple. a ceramic capacitor with a low esr value will provide the lowest voltage ripple and is therefore recommended. a capacitance in the range of 33f to 47f is suffcient. capacitor voltage ratings needs to be selected to have an adequate margin against the highest output voltage. led current selection the led current is controlled by the current sense feedback resistor r fb , the current sense feedback ref - erence voltage ( v fb ) is 0.3v. in order to obtain accu- is 0.3v. in order to obtain accu- 0.3 v. in order to obtain accu- v. in order to obtain accu- obtain accu- accu - rate led currents, precision resistors are the preferred type with a 1% tolerance. the led current ( i led ) can be calculated from the following formula. i led = v fb r fb = 0.3v r fb cs pin and fb pin rc filter whether an rc low pass filer is employed or not depends upon the design layout and must be considered on a case-by-case basis.
rev. 1.00 6 august 14, 2015 HT7963 layout considerations circuit board layout is a very important consideration for switching regulators if they are to function properly. poor circuit layout may result in related noise problems. in order to minimise emi and switching noise, the following guidelines should be adhered to: ? all tracks should be as wide as possible ? the input and output capacitors, c in and c out , should be placed close to the vin, vo ut and gnd pins ? the schottky diode, d1, and inductor, l, must be placed close to the power mosfet drain ? feedback resistor, r fb , must be placed close to the fb and gnd pins ? a full ground plane is always helpful for better emi performance a recommended pcb layout with component locations is shown below. 57mm top layer bottom layer 35mm
rev. 1.00 7 august 14, 2015 HT7963 fig.2 feedback voltage vs temperature fig.3 cs protection voltage vs temperature fig.4 fb protection voltage vs temperature fig.5 frequency vs temperature fig.6 operating current vs temperature fig.7 ovp protection voltage vs temperature typical performance characteristics
rev. 1.00 8 august 14, 2015 HT7963 dimming linearity fig.8 v in =12v, led=16s5p, v out =44.5v, i out =453ma, c out =47f, p out =20w (ta=25c) fig.10 v in =24v, led=30s5p, v out =81.5v, i out =245ma, c out =47f, p out =20w (ta=25c) fig.12 v in =30v, led=40s5p, v out =106.8v, i out =188ma, c out =47f, p out =20w (ta=25c) fig.9 v in =12v, led=16s5p, v out =45.8v, i out =719ma, c out =47f, p out =33w (ta=25c) fig.11 v in =24v, led=30s5p, v out =84.3v, i out =602ma, c out =47f, p out =50w (ta=25c) fig.13 v in =30v, led=40s5p, v out =110.5v, i out =451ma, c out =47f, p out =50w (ta=25c)
rev. 1.00 9 august 14, 2015 HT7963 package information note that the package information provided here is for consultation purposes only. as this information may be updated at regular intervals users are reminded to consult the holtek website for the latest version of the package/ carton information . additional supplementary information with regard to packaging is listed below. click on the relevant section to be transferred to the relevant website page. ? further package information (include outline dimensions, product tape and reel specifcations) ? packing meterials information ? carton information
rev. 1.00 10 august 14, 2015 HT7963 8-pin sop (150mil) outline dimensions symbol dimensions in inch min. nom. max. a 0.236 bsc b 0.154 bsc c 0.012 0.020 c' 0.193 bsc d 0.069 e 0.050 bsc f 0.004 0.010 g 0.016 0.050 h 0.004 0.010 0 8 symbol dimensions in mm min. nom. max. a 6.00 bsc b 3.90 bsc c 0.31 0.51 c' 4.90 bsc d 1.75 e 1.27 bsc f 0.10 0.25 g 0.40 1.27 h 0.10 0.25 0 8
rev. 1.00 11 august 14, 2015 HT7963 copyright ? 2015 by holtek semiconductor inc. the information appearing in this data sheet is believed to be accurate at the time of publication. however, holtek assumes no responsibility arising from the use of the specifcations described. the applications mentioned herein are used solely for the purpose of illustration and holtek makes no warranty or representation that such applications will be suitable without further modification, nor recommends the use of its products for application that may present a risk to human life due to malfunction or otherwise. holtek's products are not authorized for use as critical components in life support devices or systems. holtek reserves the right to alter its products without prior notifcation. for the most up-to-date information, please visit our web site at http://www.holtek.com.tw.

▲Up To Search▲

Price & Availability of HT7963

	To Download HT7963 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .