Supertex inc. HV9861A LED Driver with Average-Mode, Constant Current Control Features ►► ►► ►► ►► ►► ►► General Description Fast average current control Programmable constant off-time switching PWM / linear dimming input Output short circuit protection with skip mode Ambient operating temperature -40OC to +125OC Pin-compatible with the HV9910B and HV9961 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 (VDD) for the HV9861A is 7.5V. Applications ►► ►► ►► ►► ►► ►► The HV9861A is a patented, average-mode, constant current 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, and therefore greatly improves the accuracy, line and load regulation of the LED current without any need for loop compensation or highside current sensing. The output LED current accuracy is ±3%. DC/DC or AC/DC LED driver applications LED backlight driver for LCD displays General purpose constant current source LED signage and displays Architectural and decorative LED lighting LED street lighting The IC can be powered from a 12 - 450V supply. A PWM dimming input is provided that accepts an external 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. The IC is pin-to-pin compatible with the Supertex HV9910B and HV9961, and can be used as a drop-in replacement for many applications to improve the LED current accuracy and regulation. Typical Application Circuit 12 to 450VDC LED Load 1 VIN 5 PWMD GATE 4 HV9861A 6 VDD CS 2 7 LD RT 8 GND 3 Supertex inc. RT RCS Sets LED Current ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com HV9861A Pin Description Ordering Information Package Options 8-Lead SOIC Device 16 NC NC 2 15 NC NC 3 14 RT CS 4 13 LD 16-Lead SOIC 4.90x3.90mm body 1.75mm height (max) 1.27mm pitch 9.90x3.90mm body 1.75mm height (max) 1.27mm pitch HV9861ALG-G HV9861ANG-G HV9861A VIN 1 -G indicates package is RoHS compliant (‘Green’) VIN 1 8 RT CS 2 7 LD GND 5 6 VDD GND 3 5 PWMD GATE 4 12 VDD NC 6 11 NC NC 7 10 NC GATE 8 8-Lead SOIC (LG) (top view) 9 16-Lead SOIC (NG) (top view) Product Marking Absolute Maximum Ratings Parameter Value VIN to GND -0.5V to +470V VDD to GND 12V CS, LD, PWMD, GATE, RT to GND Y = Last Digit of Year Sealed WW = Week Sealed L = Lot Number = “Green” Packaging YWW 9861A LLLL Package may or may not include the following marks: Si or 8-Lead SOIC (LG) -0.3V to (VDD +0.3V) Junction temperature range -40°C to +150°C Storage temperature range -65°C to +150°C Top Marking HV9861ANG YWW LLLLLLLL Bottom Marking Continuous power dissipation (TA = +25°C) 8-Lead SOIC 16-Lead SOIC 650mW 1000mW 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. CCCCCCCCC AAA Y = Last Digit of Year Sealed WW = Week Sealed L = Lot Number C = Country of Origin* A = Assembler ID* = “Green” Packaging *May be part of top marking Package may or may not include the following marks: Si or 16-Lead SOIC (NG) Thermal Resistance Package θJA 8-Lead SOIC 128OC/W 16-Lead SOIC 82OC/W Electrical Characteristics (Specifications are at T A Sym Description = 25°C. VIN = 12V, VLD = VDD, PWMD = VDD unless otherwise noted)) Min Typ Max Unit Conditions Input VINDC Input DC supply voltage range1 * 12 - 450 V IINSD Shut-down mode supply current * - 0.5 1 mA DC input voltage Pin PWMD to GND Notes: 1. Also limited by package power dissipation limit, whichever is lower. * Denotes the specifications which apply over the full operating ambient temperature range of -40°C < TA < +125°C. Supertex inc. PWMD ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com 2 HV9861A Electrical Characteristics (Specifications are at T A Sym Description = 25°C. VIN = 12V, VLD = VDD, PWMD = VDD unless otherwise noted)) Min Typ Max Unit Conditions Internal Regulator VDD Internally regulated voltage - 7.25 7.50 7.75 V ΔVDD, line Line regulation of VDD - - - 1 V ΔVDD, load Load regulation of VDD - - - 100 mV * 6.45 - - V VIN rising - - 500 - mV VIN falling VDD voltage margin * 500 - - mV ∆VDD(UV) = VDD - UVLO Maximum input current (limited by UVLO) # 3.5 - - # 1.5 - - VDD undervoltage lockout threshold VDD undervoltage lockout hysteresis UVLO ∆UVLO ∆VDD(UV) IIN,MAX mA 500pF at GATE; RT = 226kΩ VIN = 12 - 450V, 500pF at GATE; RT = 226kΩ IDD(ext) = 0 - 1mA, 500pF at GATE; RT = 226kΩ VIN = 12V, TA = 25OC VIN = 12V, TA = 125OC PWM Dimming VEN(lo) PWMD input low voltage * - - 0.8 V VIN = 12 - 450V VEN(hi) PWMD input high voltage * 2.2 - - V VIN = 12 - 450V Internal pull-down current at PWMD - 8.5 - 13.5 μA VPWMD = 0.8V Current sense reference voltage - 262 - 280 mV --- AV(LD) LD-to-CS voltage ratio - 0.175 - 0.182 - --- AV • VLD(OFFSET) LD-to-CS voltage offset - -10 - 10 mV Offset = VCS - (AV(LD) • VLD); VLD = 1.2V CS threshold temp regulation # - - 5 mV --- LD input voltage, shutdown - - 150 - mV VLD falling LD input voltage, enable - - 200 - mV VLD rising TBLANK Current sense blanking interval * 140 - 290 ns --- TON(min) Minimum on-time - - - 760 ns CS = VCS + 30mV Maximum steady-state duty cycle * 80 - - % Reduction in output LED current may occur beyond this duty cycle Hiccup threshold voltage * 410 - 500 mV --- TDELAY Current limit delay CS-to-GATE - - - 150 ns CS = VCS + 30mV THICCUP Short circuit hiccup time - 500 - 850 μs --- TON(min) Minimum on-time (short circuit) - - - 430 ns CS = VDD IEN Average Current Sense Logic VCS ΔVCS(TEMP) VLD(OFF) ΔVLD(OFF) DMAX Short Circuit Protection VCS Notes: * Denotes the specifications which apply over the full operating ambient temperature range of -40°C < TA < +125°C. # Guaranteed by design. Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com 3 HV9861A Electrical Characteristics (Specifications are at T A Sym Description = 25°C. VIN = 12V, VLD = VDD, PWMD = VDD unless otherwise noted)) Min Typ Max Unit Conditions - 32 40 48 - 8 10 12 Sourcing current - 0.165 - - A VGATE = 0V, VDD = 7.5V ISINK Sinking current - 0.165 - - A VGATE = VDD, VDD = 7.5V tRISE Output rise time - - 30 50 ns CGATE = 500pF, VDD = 7.5V tFALL Output fall time - - 30 50 ns CGATE = 500pF, VDD = 7.5V Shut-down temperature # 128 140 - O Hysteresis # - 20 - O TOFF Timer TOFF Off-time μs RT = 1MΩ RT = 226kΩ GATE Driver ISOURCE Over-temperature Protection TSD ΔTSD C --- C --- Notes: # Guaranteed by design. Functional Block Diagram VIN Regulator VDD + - UVLO POR 0.15/0.20V LD + - MIN (VLD • 0.18, 0.27V) GATE Auto-REF CS Latch Enable Blanking IN Average Current Control Logic OUT PWMD GND 0.45V + - 11µA R Q S Q CLK HV9861A Supertex inc. 650µs TOFF Timer i Current Mirror RT ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com 4 HV9861A General Description Peak-current control (as in the HV9910B) of a buck converter is the most economical and simple way to regulate its output current. However, it suffers accuracy and regulation problems that arise from the so-called peak-to-average current error, contributed 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 potential in a buck converter when the control switch is referenced to the same ground potential because the control switch is only conducting for small periods. While it is very simple to detect the peak current in the switch, controlling the average inductor current is usually implemented by level translating the sense signal from +VIN. Though this is practical for relatively low input voltage VIN, this type of average-current control may become excessively complex and expensive in offline AC or other high-voltage DC applications. The HV9861A employs Supertex’ patented 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 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 improve the LED current regulation over a wide range of input voltages. (Note that, unlike the HV9910B, this IC does not support the constant-frequency mode of operation.) 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 equation governing the off-time of the GATE output is given by: RT (kΩ) TOFF (µs) = + 0.3 25 Within the range of 30kΩ ≤ RT ≤ 1.0MΩ. (1) Average Current Control Feedback and Output Short Circuit Protection The current through the switching MOSFET source is averaged and used to give constant-current feedback. This current is detected using a sense resistor at the CS pin. The Supertex inc. feedback operates in a fast open-loop mode. No compensation is required. Output current is programmed simply as: ILED = 0.27V RCS (2) When the voltage at the LD input VLD ≥ 1.5V. Otherwise: I = LED VLD • 0.18 RCS (3) The above equations are 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 peak-to-peak, full load, DC current. Hence, the recommended inductance can be calculated as: LO = VO(MAX) • TOFF 0.4 • IO (4) 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 HV9861A LED driver. Reducing the output LED voltage VO below VO(MIN) = VIN • DMIN, where DMIN = 760ns/(TOFF +760ns), may also result in the loss of regulation of the LED current. This condition, however, causes an increase in the LED current and can potentially trip the short-circuit protection comparator. The typical output characteristic of the HV9861A LED driver is shown in Fig.1. The corresponding HV9910B characteristic is given for comparison. Output Characteristics 0.60 0.55 LED Current (A) Application Information VIN = 170VDC 0.50 0.45 0.40 HV9861A 0.35 0.30 0.25 HV9910B 0 10 20 30 40 50 60 Output Voltage (V) Fig.1. Typical output characteristic of an HV9861A LED driver. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com 5 HV9861A The short circuit protection comparator trips when the voltage at CS exceeds 0.45V. When this occurs, the GATE offtime THICCUP = 650µs 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. 2. 0.45V/RCS 650µs Fig.2. Short-circuit inductor current. A leading-edge blanking delay is provided at CS to prevent false triggering of the current feedback and the short circuit protection. Linear Dimming When the voltage at LD falls below 1.5V, the internal 270mV reference to the constant-current feedback becomes overridden by VLD • 0.18. As long as the current in the inductor remains continuous, the LED current is given by the equation (3) above. However, when VLD falls below 150mV, the GATE output becomes disabled. The GATE signal recovers, when VLD exceeds 200mV. This is required in some applications to be able to shut the LED lamp off with the same signal input that controls the brightness. The typical linear dimming response is shown in Fig.3. LD Response Characteristics 0.40 0.35 LED Current (A) 0.30 pulse-width modulated signal of a measured amplitude below 1.5V should be applied at LD. Input Voltage Regulator The HV9861A can be powered directly from a 12 ~ 450VDC supply through its VIN input. When this voltage is applied at the VIN pin, the HV9861A maintains a constant 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, whichever 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 GATE 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, continuous voltage at VIN is limited by the power dissipation in the package. For example, when these ICs draw IIN = 2.0mA from the VIN input, and the 8-lead SOIC package is used, the maximum continuous voltage at VIN is limited to: VIN(MAX) = TJ(MAX) - TA Rθ,J-A • IIN = 390V (5) Where the ambient temperature TA = 25OC, the maximum working junction temperature TJ(MAX) = 125OC, the junctionto-ambient thermal resistance Rθ,JA = 128OC/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 example, using a 100V Zener diode will allow the circuit to work up to 490V. The input current drawn from the VIN pin is represented by the following equation: 0.25 0.20 0.15 (6) In the above equation, fS is the switching frequency, and QG is the GATE charge of the external FET obtained from the manufacturer’s datasheet. 0.10 0.05 0 IIN ≈ 1.0mA + QG • fS 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 LD (V) Fig.3. Typical linear dimming response of an HV9861A LED driver The linear dimming input could also be used for “mixedmode” dimming to expand the dimming ratio. In such case a Supertex inc. GATE Output The GATE output of the HV9861A is used to drive an external MOSFET. It is recommended that the gate charge QG of the external MOSFET be less than 25nC for switching frequencies ≤100kHz and less than 15nC for switching frequencies >100kHz. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com 6 HV9861A 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 Fig. 4. The rising and falling edges are limited by the current slew rate in the inductor. The first switching cycle is terminated upon reaching the 270mV (VLD • 0.18) level at CS. The circuit is further reaching its steady-state within 3~4 switching cycles regardless of the switching frequency. Fig.4. Typical PWM dimming response of an HV9861A LED driver. [CH2 (red): PWMD; CH4 (green): Inductor Current; CH3 (blue): Same as HV9910B for comparison] Pin Description Pin # Function Description 8-Lead SOIC 16-Lead SOIC 1 1 VIN This pin is the input of an 12 - 450V linear regulator. 2 4 CS This pin is the current sense pin used to sense the FET current by means of an external sense resistor. 3 5 GND Ground return for all internal circuitry. This pin must be electrically connected to the ground of the power train. 4 8 GATE This pin is the output GATE driver for an external N-channel power MOSFET. 5 9 PWMD This is the PWM dimming input of the IC. When this pin is pulled to GND, the gate driver is turned off. When the pin is pulled high, the gate driver operates normally. 6 12 VDD This is the power supply pin for all internal circuits. It must be bypassed with a low ESR capacitor to GND (at least 0.1μF). 7 13 LD This pin is the linear dimming input, and it 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. 8 14 RT A resistor connected between this pin and GND programs the GATE offtime. - 2, 3, 6, 7, 10, 11, 15, 16 NC No connection. Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com 7 HV9861A 8-Lead SOIC (Narrow Body) Package Outline (LG) 4.90x3.90mm body, 1.75mm height (max), 1.27mm pitch D θ1 8 E E1 L2 Note 1 (Index Area D/2 x E1/2) L 1 θ L1 Top View Gauge Plane Seating Plane View B A View B Note 1 h h A A2 Seating Plane b e A1 A Side View View A-A Note: 1. This chamfer feature is optional. 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 MIN 1.35* 0.10 1.25 0.31 NOM - - - - MAX 1.75 0.25 1.65* 0.51 D E E1 4.80* 5.80* 3.80* 4.90 6.00 3.90 5.00* 6.20* 4.00* e 1.27 BSC h L 0.25 0.40 - - 0.50 1.27 L1 1.04 REF L2 0.25 BSC JEDEC Registration MS-012, Variation AA, Issue E, Sept. 2005. * This dimension is not specified in the JEDEC drawing. Drawings are not to scale. Supertex Doc. #: DSPD-8SOLGTG, Version I041309. Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com 8 θ θ1 0O 5O - - 8O 15O HV9861A 16-Lead SOIC (Narrow Body) Package Outline (NG) 9.90x3.90mm body, 1.75mm height (max), 1.27mm pitch D 16 θ1 E1 E Note 1 (Index Area D/2 x E1/2) L2 1 L Top View View B A A A2 e A1 View B h h Seating Plane Seating Plane θ L1 Gauge Plane Note 1 b Side View View A-A A Note: 1. This chamfer feature is optional. If it is not present, then 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 1.35* 0.10 1.25 0.31 9.80* 5.80* 3.80* NOM - - - - 9.90 6.00 MAX 1.75 0.25 1.65* 0.51 3.90 10.00* 6.20* 4.00* e 1.27 BSC h L 0.25 0.40 - - 0.50 1.27 L1 L2 1.04 0.25 REF BSC θ θ1 0O 5O - - 8O 15O JEDEC Registration MS-012, Variation AC, Issue E, Sept. 2005. * This dimension is not specified in the JEDEC drawing. Drawings are not to scale. Supertex Doc. #: DSPD-16SONG, Version G041309. (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-HV9861A A010312 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com 9