HV9919B Hysteretic, Buck, High Brightness LED Driver with High-Side Current Sensing Features Description • • • • • • • • • HV9919B is a Pulse-Width Modulation (PWM) controller IC designed to drive high-brightness LEDs using a buck topology. It operates from an input voltage of 4.5 to 40VDC and employs hysteretic control, with a highside current sense resistor, to set the constant output current. Hysteretic control with high-side current sensing Wide input-voltage range: 4.5 to 40V >90% Efficiency Typical ±5% LED current accuracy Up to 2.0MHz switching frequency Adjustable constant LED current Analog or PWM control signal for PWM dimming Over-temperature protection -40ºC to +125ºC operating temperature range Applications • • • • Low-voltage industrial and architectural lighting General purpose constant current source Signage and decorative LED lighting Indicator and emergency lighting Set the operating frequency range by selecting the proper inductor. Operation at high switching frequency is possible since the hysteretic control maintains accuracy even at high frequencies. This permits the use of small inductors and capacitors, minimizing space and cost in the overall system. LED brightness control is achieved with PWM dimming from an analog or PWM input signal. Unique PWM circuitry allows true constant color with a high dimming range. The dimming frequency is programmed using a single external capacitor. HV9919B comes in a small, 8-Lead DFN package and is ideal for industrial and general lighting applications. Package Type CS 1 8 GATE VIN 2 7 GND GND RAMP 3 6 VDD ADIM 4 5 DIM 8-Lead DFN See Table 2-1 for pin information 2015 Microchip Technology Inc. 20005462B-page 1 HV9919B Block Diagram VIN VDD REGULATOR + - CS CURRENT SENSE COMPARATOR GATE DRIVER GATE + BANDGAP REF DIM UVLO COMPARATOR GND PWM RAMP 0.1~1.9V RAMP + HV9919B ADIM Typical Application Circuit RSENSE L CIN CS RAMP 0 - 2.0V ADIM DIM VIN VDD GATE GND HV9919B 20005462B-page 2 2015 Microchip Technology Inc. HV9919B 1.0 ELECTRICAL CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS† VIN to GND .................................................................................................................................................-0.3V to +45V VDD to GND...............................................................................................................................................-0.3V to +6.0V GATE, RAMP, DIM, ADIM to GND .............................................................................................................-0.3V to +VDD CS to VIN ...................................................................................................................................................-1.0V to +0.3V Continuous total power dissipation (TA = 25.°C) ..................................................................................................... 1.6W Operating temperature range................................................................................................................ -40°C to +125°C Junction temperature ...........................................................................................................................................+150°C Storage temperature range ................................................................................................................... -65°C to +150°C † Notice: Stresses above those listed under “Maximum Ratings” may cause permanent damage 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 specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. TABLE 1-1: ELECTRICAL CHARACTERISTICS (SHEET 1 OF 2) Electrical Specifications: VIN=12V, VDIM = VDD, VRAMP = GND, CVDD = 1.0 µF, RCS = 0.5Ω, TA= TJ= -40°C to +125°C, unless otherwise noted. (Note 1) Parameter Symbol Input DC supply voltage range Internally regulated voltage Supply current Shutdown supply current VIN VDD IIN IIN, SDN Current limit IIN, LIM Switching frequency fSW VDD Undervoltage lockout threshUVLO old VDD Undervoltage lockout hysteresis ∆UVLO Sense Comparator Sense voltage threshold high VCS(HI) Sense voltage threshold low VCS(LO) Average sense voltage VCS(AVG) Min Typ Max Units Conditions 4.5 4.5 - 11 5.5 - 40 5.5 1.5 900 2.0 MHz - - 4.5 V VDD rising - 500 - mV VDD falling 186 230 170 200 214 mV mV mV (VIN- VCS) rising (VIN- VCS) falling VCS(AVG) = 0.5(VCS(HI) + VCS(LO)) Falling edge of (VIN- VCS) = VRS(LO)- 70mV V V mA µA mA Propagation delay to output high tDPDH - 70 - ns Propagation delay to output low tDPDL - 70 - ns Current-sense input current Current-sense threshold hysteresis DIM Input Pin DIM input high voltage Pin DIM input low voltage ICS VCS(HYS) 15 56 1.0 98 µA mV VIH VIL 2.2 - - 0.7 V V Turn-on time tON - 100 - ns Turn-off time tOFF - 100 - ns 2015 Microchip Technology Inc. DC input voltage VIN= 6.0 to 40V GATE open DIM< 0.7V VIN= 4.5V, VDD= 0V VIN= 4.5V, VDD= 4.0V – Rising edge of (VIN- VCS) = VRS(HI)+ 70mV (VIN- VCS) = 200mV VCS(HYS) = VCS(HI) - VCS(LO) – – DIM rising edge to VGATE= 0.5 x VDD, CGATE= 2.0nF DIM falling edge to VGATE= 0.5 x VDD, CGATE=2.0nF 20005462B-page 3 HV9919B TABLE 1-1: ELECTRICAL CHARACTERISTICS (SHEET 2 OF 2) Electrical Specifications: VIN=12V, VDIM = VDD, VRAMP = GND, CVDD = 1.0 µF, RCS = 0.5Ω, TA= TJ= -40°C to +125°C, unless otherwise noted. (Note 1) Parameter GATE Driver GATE current, source Symbol IGATE Min Typ Max 0.3 0.5 - A VGATE= GND, (Note 2) 1.0 40 17 - 55 25 0.5 A ns ns V V VGATE= VDD, (Note 2) CGATE= 2.0nF CGATE= 2.0nF IGATE= 10mA IGATE= -10mA 140 60 - ºC ºC (Note 2) (Note 2) 0.1 - 308 1380 2.1 +35 GATE current, sink 0.7 GATE output rise time TRISE GATE output fall time TFALL GATE high output voltage VGATE(HI) VDD-0.5 GATE low output voltage VGATE(LO) Over-Temperature Protection Over temperature trip limit TOT 128 Temperature hysteresis ∆THYST Analog Control of PWM Dimming Dimming frequency fRAMP RAMP threshold, Low RAMP threshold, High ADIM offset voltage VLOW VHIGH VOS 114 529 1.8 -35 Units Conditions Hz V V mV CRAMP= 47nF CRAMP= 10nF – – – Note 1: Specification is obtained by characterization and is 100% tested at TA = 25°C. 2: Specification is obtained by characterization and not 100% tested TEMPERATURE SPECIFICATIONS Electrical Specifications: Unless otherwise specified, for all specifications TA =TJ = +25°C Parameter Symbol Min Typ Max Units Conditions Temperature Ranges Operating Temperature -40 Storage Temperature -65 – 125 °C – 150 °C 60 – °C/W Package Thermal Resistances Thermal Resistance, DFN 20005462B-page 4 θja Mounted on FR-4 board, 25 mm x 25 mm x 1.57 mm 2015 Microchip Technology Inc. HV9919B 2.0 PIN DESCRIPTION The locations of the pins are listed in Features. TABLE 2-1: PIN DESCRIPTION Pin # Symbol 1 CS Current sense input. Senses LED string current. 2 VIN Input voltage 4.5 to 40V DC. 3 RAMP Analog PWM dimming ramp output. 4 ADIM Analog 0~2.0V signal input for analog control of PWM dimming. 5 DIM PWM signal input. 6 VDD Internally regulated supply voltage. Connect a capacitor from VDD to ground. 7 GND Device ground. 8 GATE Drives gate of external MOSFET. TAB GND Must be wired to pin 7 on PCB. 2015 Microchip Technology Inc. Description 20005462B-page 5 HV9919B 3.0 APPLICATION INFORMATION HV9919B is a step-down, constant current, HighBrightness LED (HB LED) driver. The device operates from a 4.5 to 40V input voltage range and provides the gate drive output to an external N-channel MOSFET. A high-side, current-sense resistor sets the output current and a dedicated PWM Dimming Input (DIM) allows for a wide range of dimming duty ratios. The PWM dimming could also be achieved by applying a DC voltage between 0 and 2.0V to the Analog Dimming Input (ADIM). In this case, the dimming frequency can be programmed using a single capacitor at the RAMP pin. When the analog control of PWM dimming feature is not used, RAMP must be wired to GND, and ADIM should be connected to VDD. One possible application of the ADIM feature of HV9919B may include protection of the LED load from over-temperature by connecting an NTC thermistor at ADIM, as shown in Figure 3-1 VDD HV9919B The high-side current setting and sensing scheme minimizes the number of external components while delivering LED current with a ±8% accuracy, using a 1% sense resistor. 3.1 5.0V Regulator VDD is the output of a 5.0V regulator capable of sourcing 5.0 mA. Bypass VDD to GND with a 1.0μF capacitor. 3.3 DIM Input HV9919B allows dimming with a PWM signal at the DIM input. A logic level below 0.7V at DIM forces the GATE output low, turning off the LED current. To turn the LED current on, the logic level at DIM must be at least 2.2V. 3.4 NTC GND Undervoltage Lockout (UVLO) HV9919B includes a 3.7V Under-Voltage lockout (UVLO) with 500mV hysteresis. When VDD falls below 3.7V, GATE goes low, turning off the external N-channel MOSFET. GATE goes high once VDD is 4.5V or higher. 3.2 ADIM ADIM and RAMP Inputs The PWM dimming scheme can be also implemented by applying an analog control signal to ADIM pin. If an analog control signal of 0 – 2.0V is applied to ADIM, the device compares this analog input to a voltage ramp to pulse-width-modulate the LED current. Connecting an external capacitor to RAMP programs the PWM dimming ramp frequency. 1 f PWM = -----------------------------------------C RAMP 120K DIM and ADIM inputs can be used simultaneously. In such a case, fPWM(MAX) must be selected lower than the frequency of the dimming signal at DIM. The smaller dimming duty cycle of ADIM and DIM will determine the GATE signal. 20005462B-page 6 FIGURE 3-1: 3.5 NTC Thermistor at ADIM Setting LED Current with External Resistor RSENSE The output current in the LED is determined by the external current sense resistor (RSENSE) connected between VIN and CS. Disregarding the effect of the propagation delays, the sense resistor can be calculated as: 1 V CS HI + V CS LO R SENSE --- ---------------------------------------------------- = 200mV -----------------I LED 2 I LED 3.6 Selecting Buck Inductor L HV9919B regulates the LED output current using a comparator with hysteresis, see Figure 3-2. As the current through the inductor ramps up and the voltage across the sense resistor reaches the upper threshold, the voltage at GATE goes low, turning off the external MOSFET. The MOSFET turns on again when the inductor current ramps down through the freewheeling diode, until the voltage across the sense resistor equals the lower threshold. Use the following equation to determine the inductor value for a desired value of operating frequency fS: V IN – V OUT V OUT V IN – V OUT tDPDL L = -------------------------------------------------– ---------------------------------------------f S V IN I O I O V OUT t DPDH – -----------------------------I O 2015 Microchip Technology Inc. HV9919B This ripple can be calculated from the following equation: Where: V CS HI – V CS LO I O = ---------------------------------------------R SENSE V IN – V OUT t DPDL V OUT t DPDH - + -----------------------------I = I O + -------------------------------------------------L L and tDPDL, tDPDH are the propagation delays. The current ripple ∆I in the inductor L is greater than ∆IO. VRS(HI) RSENSE tDPDL ILED VRS(LO) RSENSE For the purpose of the proper inductor selection, note that the maximum switching frequency occurs at the highest VINand VOUT= VIN/2. TS = 1/fS tDPDH ΔI ΔIO t VDIM t FIGURE 3-2: 3.7 Regulating LED output MOSFET Selection MOSFET selection is based on the maximum input operating voltage VIN, output current ILED, and operating switching frequency. Choose a logic-level MOSFET that has a higher breakdown voltage than the maximum operation voltage, low RDS(ON), and low total gate charge for better efficiency. 3.8 Freewheeling Diode Selection The forward voltage of the freewheeling diode should be as low as possible for better efficiency. A Schottky diode is a good choice as long as the breakdown voltage is high enough to withstand the maximum operating voltage. The forward-current rating of the diode must be at least equal to the maximum LED current. 3.9 3.10 PCB Layout Guidelines Careful PCB layout is critical to achieve low switching losses and stable operation. Use a multilayer board whenever possible for better noise immunity. Minimize ground noise by connecting high-current ground returns, the input bypass capacitor ground lead, and the output filter ground lead to a single point (star ground configuration). The fast di/dt loop is formed by the input capacitor CIN, the free-wheeling diode and the MOSFET. To minimize noise interaction, this loop area should be as small as possible. Place RSENSE as close as possible to the input filter and VIN. For better noise immunity, a Kelvin connection is strongly recommended between CS and RSENSE. Connect the exposed tab of the IC to a large-area ground plane for improved power dissipation. LED Current Ripple The LED current ripple is equal to the inductor-current ripple. In cases when a lower LED current ripple is needed, a capacitor can be placed across the LED terminals. 2015 Microchip Technology Inc. 20005462B-page 7 HV9919B 4.0 PACKAGING INFORMATION 4.1 Package Marking Information 8-lead DFN Example XXXX YYWW NNN 9919 1542 343 Legend: XX...X Y YY WW NNN e3 * Note: 20005462B-page 8 Product Code or Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week ‘01’) Alphanumeric traceability code Pb-free JEDEC® designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC designator ( e3 ) can be found on the outer packaging for this package. In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for product code or customer-specific information. Package may or not include the corporate logo. 2015 Microchip Technology Inc. HV9919B Note: For the most current package drawings, see the Microchip Packaging Specification at www.microchip.com/packaging. 2015 Microchip Technology Inc. 20005462B-page 9 HV9919B APPENDIX A: REVISION HISTORY Revision A (November 2015) • • • • • • Updated file to Microchip format. Revised Absolute Maximum Ratings†. Modified values and notes in Table 1-1. Added condition to Temperature Specifications. Changed value in Section 3.2 “5.0V Regulator”. Wording change in Section 3.7 “MOSFET Selection”. • Minor text changes throughout. Revision B (December 2015) • Updated Revision History. 20005462B-page 10 2015 Microchip Technology Inc. HV9919B PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. Device - XX X - Package Environmental Options X Media Type Device: HV9919B = Hysteretic, Buck, High Brightness LED Driver with High-Side Current Sensing Package: K7 = 48-lead DFN Environmental G = Lead (Pb)-free/ROHS-compliant package Media Type: (blank) = 3000/Reel 2015 Microchip Technology Inc. Examples: a) HV9919BK7-G 8-Lead DFN package, 3000/Reel 20005462B-page 11 Note the following details of the code protection feature on Microchip devices: • Microchip products meet the specification contained in their particular Microchip Data Sheet. • Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. • There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. • Microchip is willing to work with the customer who is concerned about the integrity of their code. • Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.” Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. 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All other trademarks mentioned herein are property of their respective companies. © 2015, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. ISBN: 978-1-5224-0111-7 QUALITYMANAGEMENTSYSTEM CERTIFIEDBYDNV == ISO/TS16949== 20005462B-page 12 Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. 2015 Microchip Technology Inc. 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