Supertex inc. HV9967B Integrated LED Driver with Average-Mode Current Control Features ►► ►► ►► ►► ►► ►► ►► ►► ►► General Description 3% accurate LED current Integrated 60V, 0.8Ω MOSFET Low sensitivity to external component variation Single resistor LED current setting Fixed off-time control PWM dimming input Output short circuit protection with skip mode Over-temperature protection Available in compact 8-Lead MSOP and 8-Lead DFN packages The HV9967B is an average-mode current control LED driver IC operating in a constant off-time mode. The IC features an integrated 60V, 0.8Ω MOSFET that can be used as a stand-alone buck converter switch, or connected as a source driver for driving an external high-voltage depletion-mode MOSFET. The HV9967B is powered through its switching output when the integrated switch is off. Hence, the same external MOSFET can be used as a high-voltage linear regulator for powering the IC. The LED current is programmed with one external resistor. The average-mode current control method does not produce a peakto-average error, and therefore greatly improves current accuracy and line and load regulation of the LED current without any need for loop compensation or direct sensing of the LED current at a high-voltage potential. The auto-zero circuit cancels the effects of the input offset voltage and of the propagation delay of the current sense comparator. Applications ►► ►► ►► ►► ►► DC/DC or AC/DC LED drivers RGB backlighting drivers for flat panel displays General purpose constant current source Signage and decorative LED lighting Chargers Typical Application Circuit 8.0 - 60VDC + CO D1 CIN LED String U1 4 2 RSENSE SW PWMD HV9967B RSENSE PGND AGND 3 7 VDD RT 1 L1 8 6 CDD RT Doc.# DSFP-HV9967B B060712 Supertex inc. www.supertex.com HV9967B Pin Configurations Ordering Information Part Number Package Options Packing HV9967BK7-G 8-Lead DFN (3x3mm) 3000/Reel RSENSE 2 HV9967BMG-G 8-Lead MSOP 2500/Reel PGND 3 SW 1 GND PWMD 4 -G indicates package is RoHS compliant (‘Green’) 8 VDD 7 AGND 6 RT 5 NC 8-Lead DFN (K7) (top view) Absolute Maximum Ratings* Parameter Value SW to GND -0.5V to +65V VDD to GND -0.3V to 6.0V Other I/O to GND -0.3V to (VDD + 0.3V) RT, ISET 2.0mA Continuous power dissipation (TA = +25°C) 8-Lead DFN (K7) 8-Lead MSOP (MG) -40°C to +150°C Storage temperature range -65°C to +150°C 8-Lead DFN 37OC/W 8-Lead MSOP 216 C/W RSENSE 2 7 AGND PGND 3 6 RT PWMD 4 5 NC Product Marking Y = Last Digit of Year Sealed W = Code for Week Sealed L = Lot Number = “Green” Packaging H6 7 B YWLL Package may or may not include the following marks: Si or 8-Lead DFN (K7) Top Marking 967B LLLL Typical Thermal Resistance θja VDD (top view) Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Package 8 8-Lead MSOP (MG) 1.6W 350mW Junction temperature SW 1 Bottom Marking YYWW L = Lot Number YY = Year Sealed WW = Week Sealed = “Green” Packaging O Package may or may not include the following marks: Si or 8-Lead MSOP (MG) Electrical Characteristics (The * denotes specifications which apply over the full operating ambient temperature range of -40°C < TA < 125°C. Otherwise specifications are at TA = 25°C. VSW = 10V/10mA, VDD = 5.0V unless otherwise noted) Sym Description Min Typ Max Units Conditions Input VSWDC IINSD Input DC supply voltage range * 8.0 - 60 V Shut-down mode supply current - - 0.5 1.0 mA DC input voltage Pin PWMD to GND Notes: # Not production tested; guaranteed by design or characterization. * Specifications apply over the full operating ambient temperature range of -40°C < TA < +125°C. Doc.# DSFP-HV9967B B060712 2 Supertex inc. www.supertex.com HV9967B Electrical Characteristics (cont.) (The * denotes specifications which apply over the full operating ambient temperature range of -40°C < TA < 125°C. Otherwise specifications are at TA = 25°C. VSW = 10V/10mA, VDD = 5.0V unless otherwise noted) Sym Description Min Typ Max Units Conditions Internal Regulator VDD Internally regulated voltage - 4.70 5.00 5.20 V PWMD = VDD; RT = 100kΩ UVLO VDD undervoltage lockout threshold * 4.10 - 4.70 V VDD rising, as needed to ensure IC(MIN) ΔUVLO VDD undervoltage lockout hysteresis - - 150 - mV VDD falling PWM Dimming VEN(LO) PWMD input low voltage * - - 0.8 V --- VEN(HI) PWMD input high voltage * 2.0 - - V --- Internal pull down resistance at PWMD - 50 100 150 kΩ VPWMD = 5.0V --- REN Current Control VCS(TH) RSENSE current threshold - 243 - 257 mV dVCS/dt Temperature regulation - - 0.1 - mV/ C TBLANK Current sense blanking interval * 140 - 290 ns --- TON(MIN) Minimum ON-time * - - 950 ns VRSENSE = VCS(TH) + 50mV Reduction in output LED current occurs beyond this duty cycle due to saturation of T2 timers. O * 80 - - % Hiccup threshold voltage at RSENSE * 355 - 440 mV --- TDELAY Current limit delay RSENSE to SW-OFF - - - 150 ns VRSENSE = VCS(SHORT) + 50mV THICCUP Hiccup time - - 800 - μs --- TON(MIN) Minimum ON-time (short circuit) - - - 400 ns VRSENSE = VCS(SHORT) + 50mV 28 40 48 7.0 10 12 0.7 1.0 1.2 DMAX Maximum steady-state duty cycle O Short Circuit Protection VCS(SHORT) TOFF Timer TOFF OFF time * RT = 400kΩ μs RT = 100kΩ RT = 10kΩ SW Output RON IC ON resistance - - 0.8 - Ω VDD = 5.0V Continuous current * 0.75 - - A VDD = 4.75V, VRSENSE = 370mV, VSW =10V Shut-down temperature # 125 - - O C --- Hysteresis # - 20 - O C --- Over-temperature Protection TSD ΔTSD Notes: # Not production tested; guaranteed by design or characterization. * Specifications apply over the full operating ambient temperature range of -40°C < TA < +125°C. Doc.# DSFP-HV9967B B060712 3 Supertex inc. www.supertex.com HV9967B Functional Block Diagram VDD HV9967B 4.35V UVLO VCS REG POR L/E Blanking IN SW Average Current Control Logic OTP RSENSE VCS OUT RQ 0.4V PGND S Q SET PWMD 100kΩ PGND TOFF Timer AGND i 0.8ms RT Application Information Average Current Control Feedback and Output Short Circuit Protection General description The HV9967B employs Supertex’ proprietary control scheme, achieving 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 peak-current control ICs, such as HV9910B. The inductor current ripple amplitude does not affect this control scheme significantly, and therefore, the LED current is independent of the variation in inductance, switching frequency or output voltage. Constant off-time control of the buck converter is used for stability and to reduce input voltage regulation of the LED current. The constant-current control feedback derives the average current signal from the source current of the switching MOSFET. This current is detected using a sense resistor at the RSENSE pin. The feedback operates in a fast open-loop mode. No compensation is required. Output current is programmed simply as: OFF Timer The timing resistor connected to RT determines the off-time of the gate driver, and it must be wired to VDD. The equation governing the off-time of the GATE output is given by: TOFF = RT • 100pF VO(MAX) • TOFF LO = (3) 0.4 • IO The duty-cycle range of the current control feedback is limited to D ≤ 0.8. A reduction in the LED current may occur when the LED string voltage VO is greater than 80% of the input voltage VIN of the HV9967B LED driver. (1) within the range of 10kΩ ≤ RT ≤ 400kΩ. Doc.# DSFP-HV9967B B060712 0.25V RCS (2) The above equation is only valid for continuous conduction of the output inductor. It is a good practice to design the inductor such that the switching ripple current in it is 30~40% of its average full load DC current peak-to-peak. Hence, the recommended inductance can be calculated as: ILED = 4 Supertex inc. www.supertex.com HV9967B Reducing the output LED voltage VO below VO(MIN) = VIN • DMIN, where DMIN = 0.8µs/(TOFF + 0.8µs), may also result in the loss of regulation of the LED current. This condition, however, causes increase in the LED current and can potentially trip the short-circuit protection comparator threshold. SW Input and Linear Regulator The short circuit protection comparator trips when the voltage at RSENSE exceeds 0.4V. When this occurs, the SW off-time THICCUP = 800µs is generated to prevent stair-casing of the inductor current and potentially its saturation due to insufficient output voltage. The typical short-circuit current is shown in the waveform of Fig. 1. PWM Dimming HV9967B includes an integrated 60V, 0.8Ω switching MOSFET at the SW input. The power for the IC is supplied from a linear 5.0V regulator that is also derived from the SW input. The HV9967B features a TTL compatible dimming input PWMD. Applying a square-wave voltage to PWMD will modulate the duty ratio of the LED current accordingly. The rising and falling edges are limited by the current slew rate in the inductor. The first switching cycle is terminated upon reaching the 250mV level at RSENSE. The circuit will reach the steady state within 3~4 switching cycles regardless of the switching frequency. 0.44V/RSENSE 800µs Over-Temperature Protection The HV9967B includes over-temperature protection. Typically, when the junction temperature exceeds 145OC, switching of the SW input is disabled. The switching resumes when the temperature falls by approximately 20OC from the trip point. Fig.1. Short-circuit inductor current. A leading-edge blanking delay is provided at RSENSE to prevent false triggering of the current feedback and the short circuit protection. Pin Description Pin # Function 1 SW 2 RSENSE 3 PGND Power ground. Must be wired to AGND on PCB. 4 PWMD PWM dimming input. This TTL input enables switching of SW when in high state. 5 NC No connection. 6 RT Resistor connected between RT and VDD programs the off-time of SW. 7 AGND 8 VDD Doc.# DSFP-HV9967B B060712 Description Drain of 60V 0.8Ω NDMOS switch and input of H/V regulator. Source of NDMOS switch and current sense input. Connect a resistor to GND to program the output current and short circuit thresholds. Analog ground (0V). Power supply for all internal circuits. Bypass with a low ESR capacitor to PGND (>0.5μF). Connect GATE of external depletion-mode NFET for high-voltage operation. 5 Supertex inc. www.supertex.com HV9967B 8-Lead DFN Package Outline (K7) 3.00x3.00mm body, 0.80mm height (max), 0.65mm pitch D2 D 8 8 E E2 Note 1 (Index Area D/2 x E/2) Note 1 (Index Area D/2 x E/2) 1 1 Top View Bottom View View B Note 3 θ A A3 e b A1 L Seating Plane L1 Note 2 View B Side View Notes: 1. A Pin 1 identifier must be located in the index area indicated. The Pin 1 identifier can be: a molded mark/identifier; an embedded metal marker; or a printed indicator. 2. Depending on the method of manufacturing, a maximum of 0.15mm pullback (L1) may be present. 3. The inner tip of the lead may be either rounded or square. Symbol Dimension (mm) A A1 MIN 0.70 0.00 NOM 0.75 0.02 MAX 0.80 0.05 A3 0.20 REF b D D2 E E2 0.25 2.85* 1.60 2.85* 1.35 0.30 3.00 - 3.00 - 0.35 3.15* 2.50 3.15* 1.75 e 0.65 BSC L L1 θ 0.30 0.00* 0O 0.40 - - 0.50 0.15 14O JEDEC Registration MO-229, Variation WEEC-2, Issue C, Aug. 2003. * This dimension is not specified in the JEDEC drawing. Drawings not to scale. Supertex Doc. #: DSPD-8DFNK73X3P065, Version C081109. Doc.# DSFP-HV9967B B060712 6 Supertex inc. www.supertex.com HV9967B 8-Lead MSOP Package Outline (MG) 3.00x3.00mm body, 1.10mm height (max), 0.65mm pitch D θ1 (x4) 8 E E1 Gauge Plane L2 Note 1 (Index Area D/2 x E1/2) L 1 L1 Top View A Seating Plane θ View B View B A A2 Seating Plane b e A1 View A-A Side View A Note: 1. A Pin 1 identifier must be located in the index area indicated. The Pin 1 identifier can be: a molded mark/identifier; an embedded metal marker; or a printed indicator. Symbol Dimension (mm) A A1 A2 b D E E1 MIN 0.75* 0.00 0.75 0.22 2.80* 4.65* 2.80* NOM - - 0.85 - 3.00 4.90 3.00 MAX 1.10 0.15 0.95 0.38 3.20* 5.15* 3.20* e 0.65 BSC L 0.40 0.60 0.80 L1 L2 0.95 REF 0.25 BSC θ θ1 0O 5O - - 8O 15O JEDEC Registration MO-187, Variation AA, Issue E, Dec. 2004. * This dimension is not specified in the JEDEC drawing. Drawings are not to scale. Supertex Doc. #: DSPD-8MSOPMG, Version H041309. (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to http://www.supertex.com/packaging.html.) Supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such applications unless it receives an adequate “product liability indemnification insurance agreement.” Supertex inc. does not assume responsibility for use of devices described, and limits its liability to the replacement of the devices determined defective due to workmanship. No responsibility is assumed for possible omissions and inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications refer to the Supertex inc. (website: http//www.supertex.com) Supertex inc. ©2012 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited. Doc.# DSFP-HV9967B B060712 7 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com