LM3528TMX/NOPB

LM3528 www.ti.com SNVS513B – AUGUST 2008 – REVISED MAY 2013 LM3528 High Efficiency, Multi Display LED Driver with 128 Exponential Dimming Steps and Integrated OLED Power Supply in a 1.2mm × 1.6mm DSBGA Package Check for Samples: LM3528 FEATURES APPLICATIONS • • • • • 1 2 • • • • • • • • • • • • 128 Exponential Dimming Steps Programmable Auto-Dimming Function Up to 90% Efficient Low Profile 12 Bump DSBGA Package (1.2mm x 1.6mm x 0.6mm) Integrated OLED Display Power Supply and LED Driver Programmable Pattern Generator Output for LED Indicator Function Drives up to 12 LED’s at 20mA Drives up to 5 LED’s at 20mA and delivers 18V at 40mA 1% Accurate Current Matching Between Strings Internal Soft-Start Limits Inrush Current True Shutdown Isolation for LED’s Wide 2.5V to 5.5V Input Voltage Range 22V Over-Voltage Protection 1.25MHz Fixed Frequency Operation Dedicated Programmable General Purpose I/O Active Low Hardware Reset 10 PH 2.7V to 5.5V IN The LM3528 current mode boost converter offers two separate outputs. The first output (MAIN) is a constant current sink for driving series white LED’s. The second output (SUB/FB) is configurable as a constant current sink for series white LED bias, or as a feedback pin to set a constant output voltage for powering OLED panels. As a dual output white LED bias supply, the LM3528 adaptively regulates the supply voltage of the LED strings to maximize efficiency and insure the current sinks remain in regulation. The maximum current per output is set via a single external low power resistor. An I2C compatible interface allows for independent adjustment of the LED current in either output from 0 to max current in 128 exponential steps. When configured as a white LED + OLED bias supply the LM3528 can independently and simultaneously drive a string of up to 6 white LED’s and deliver a constant output voltage of up to 21V for OLED panels. SW OVP C 1 PF 4.4mm VIO DESCRIPTION 20 mA per string CIN 1 PF 10 k: • • • Dual Display LCD Backlighting for Portable Applications Large Format LCD Backlighting OLED Panel Power Supply Display Backlighting with Indicator Light LM3528 10 k: MAIN SCL SDA SUB/FB HWEN/PGEN/ GPIO GPIO Current Limiting Resistor SET GND RSET 1 M: 12.1 k: 6.5mm Indicator LED Dual White LED Bias Supply with Indicator LED Figure 1. Typical Application Circuit Figure 2. Typical PCB Layout 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2008–2013, Texas Instruments Incorporated LM3528 SNVS513B – AUGUST 2008 – REVISED MAY 2013 www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. DESCRIPTION (CONTINUED) Output over-voltage protection shuts down the device if VOUT rises above 22V allowing for the use of small sized low voltage output capacitors. Other features include a dedicated general purpose I/O (GPIO) and a multifunction pin (HWEN/PGEN/GPIO) which can be configured as a 32 bit pattern generator, a hardware enable input, or as a GPIO. When configured as a pattern generator, an arbitrary pattern is programmed via the I2C compatible interface and output at HWEN/PGEN/GPIO for indicator LED flashing or for external logic control. The LM3528 is offered in a tiny 12-bump DSBGA package and operates over the -40°C to +85°C temperature range. Connection Diagram Top View A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 Figure 3. 12-Bump (1.215mm × 1.615mm × 0.6mm) YFQ0012 PIN DESCRIPTIONS Pin Name A1 OVP Over-Voltage Protection Sense Connection. Connect OVP to the positive terminal of the output capacitor. A2 MAIN Main Current Sink Input. A3 SUB/FB Secondary Current Sink Input or 1.21V Feedback Connection for Constant Voltage Output. B1 GPIO1 Programmable General Purpose I/O. B2 SCL Serial Clock Input B3 SET LED Current Setting Connection. Connect a resistor from SET to GND to set the maximum LED current into MAIN or SUB/FB (when in LED mode), where ILED_MAX = 192×1.244V/RSET. C1 Function HWEN/PGEN/GPI Active High Hardware Enable Input. Programmable Pattern Generator Output, and Programmable O General Purpose I/O. C2 SDA C3 IN Serial Data Input/Output D1 VIO Logic Voltage Level Input D2 SW Drain Connection for Internal NMOS Switch D3 GND Ground Input Voltage Connection. Connect IN to the input supply, and bypass to GND with a 1µF ceramic capacitor. These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 2 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Product Folder Links: LM3528 LM3528 www.ti.com SNVS513B – AUGUST 2008 – REVISED MAY 2013 Absolute Maximum Ratings (1) (2) (3) −0.3V to 6V VIN VSW, VOVP, −0.3V to 25V VSUB/FB, VMAIN −0.3V to 23V −0.3V to 6V VSCL, VSDA, VRESET\GPIO, VIO , VSET Continuous Power Dissipation Internally Limited Junction Temperature (TJ-MAX) +150°C Storage Temperature Range -65°C to +150°C Maximum Lead Temperature (Soldering, 10s) (4) +300°C ESD Rating (5) Human Body Model (1) (2) (3) (4) (5) 2.5kV Absolute maximum ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions for which the device is intended to be functional, but device parameter specifications may not be ensured. For ensured specifications and test conditions, see the Electrical Characteristics. If Military/Aerospace specified devices are required, please contact the TI Sales Office/Distributors for availability and specifications. All voltages are with respect to the potential at the GND pin. For detailed soldering specifications and information, please refer to Texas Instruments Application Note 1112: DSBGA Wafer LEvel Chip Scale Package (SNVA009). The human body model is a 100pF capacitor discharged through 1.5kΩ resistor into each pin. (MIL-STD-883 3015.7). Operating Ratings (1) (2) VIN 2.5V to 5.5V VSW, VOVP, 0V to 23V VSUB/FB, VMAIN 0V to 21V Junction Temperature Range (TJ) (3) -40°C to +110°C Ambient Temperature Range (TA) (4) -40°C to +85°C (1) (2) (3) (4) Absolute maximum ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions for which the device is intended to be functional, but device parameter specifications may not be ensured. For ensured specifications and test conditions, see the Electrical Characteristics. All voltages are with respect to the potential at the GND pin. Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ=+150°C (typ.) and disengages at TJ=+140°C (typ.). In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = +105°C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (θJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (θJA × PD-MAX). Thermal Properties Junction to Ambient Thermal Resistance (θJA) (1) (1) 68°C/W Junction-to-ambient thermal resistance (θJA) is taken from a thermal modeling result, performed under the conditions and guidelines set forth in the JEDEC standard JESD51-7. The test board is a 4-layer FR-4 board measuring 114.3mm x 76.2mm x 1.6mm. The ground plane on the board is 113mm x 75mm. Thickness of copper layers are 71.5µm/35µm/35µm/71.5µm (2oz/1oz/1oz/2oz). Ambient temperature in simulation is 22°C, still air. Power dissipation is 1W. For more information on these topics, please refer to Texas Instruments Application Note 1112 SNVA009, and JEDEC Standard JESD51-7. Electrical Characteristics Specifications in standard type face are for TA = 25°C and those in boldface type apply over the Operating Temperature Range of TA = −40°C to +85°C. Unless otherwise specified VIN = 3.6V, VIO = 1.8V, VRESET/GPIO = VIN, VSUB/FB = VMAIN = 0.5V, R = 12.0kΩ, OLED = ‘0’, ENM = ENS = ‘1’, BSUB = BMAIN = Full Scale. (1) (2) SET Symbol ILED (1) (2) Parameter Conditions Output Current Regulation MAIN or SUB/FB Enabled UNI = ‘0’, or ‘1’, 2.5V < VIN < 5.5V Maximum Current Per Current Sink RSET = 8.0kΩ Min 18.5 Typ Max 20 22 30 Units mA All voltages are with respect to the potential at the GND pin. Min and Max limits are ensured by design, test, or statistical analysis. Typical (Typ) numbers are not ensured, but represent the most likely norm. Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Product Folder Links: LM3528 3 LM3528 SNVS513B – AUGUST 2008 – REVISED MAY 2013 www.ti.com Electrical Characteristics (continued) Specifications in standard type face are for TA = 25°C and those in boldface type apply over the Operating Temperature Range of TA = −40°C to +85°C. Unless otherwise specified VIN = 3.6V, VIO = 1.8V, VRESET/GPIO = VIN, VSUB/FB = VMAIN = 0.5V, R = 12.0kΩ, OLED = ‘0’, ENM = ENS = ‘1’, BSUB = BMAIN = Full Scale.(1) (2) SET Symbol Parameter Conditions Min Typ Max Units 0.15 1 % ILED-MATCH IMAIN to ISUB/FB Current Matching UNI = ‘1’, 2.5V < VIN < 5.5V VSET SET Pin Voltage 3.0V < VIN < 5V ILED/ISET ILED Current to ISET Current Ratio 192 VREG_CS Regulated Current Sink Headroom Voltage 500 VREG_OLED VSUB/FB Regulation Voltage in 2.5V < VIN < 5.5V, OLED = OLED Mode ‘1’ VHR Current Sink Minimum Headroom Voltage RDSON NMOS Switch On Resistance ISW = 100mA ICL NMOS Switch Current Limit 2.5V < VIN < 5.5V 645 770 900 VOVP Output Over-Voltage Protection ON Threshold, 2.5V < VIN < 5.5V 20.6 22 23 OFF Threshold, 2.7V < VIN < 5.5V 19.25 20.6 21.5 1.0 1.27 1.4 (3) 1.244 1.170 ILED = 95% of nominal 1.21 V mV 1.237 300 V mV Ω 0.43 mA V fSW Switching Frequency DMAX Maximum Duty Cycle 90 % DMIN Minimum Duty Cycle 10 % IQ Quiescent Current, Device Not Switching ISHDN Shutdown Current MHz VMAIN and VSUB/FB > VREG_CS, BSUB = BMAIN = 0x00, 2.5V < VIN < 5.5V 350 VSUB/FB > VREG_OLED, OLED=’1’, ENM=ENS=’0’, RSET Open, 2.5V < VIN < 5.5V 250 260 ENM = ENS = OLED = '0', 2.5V < VIN < 5.5V 1.8 3 µA 0.5 V 390 µA HWEN/PGEN/GPIO, GPIO1 Pin Voltage Specifications VIL Input Logic Low 2.5V < VIN 0.3V. Input Capacitor Selection Choosing the correct size and type of input capacitor helps minimize the input voltage ripple caused by the switching of the LM3528’s boost converter. For continuous inductor current operation the input voltage ripple is composed of 2 primary components, the capacitor discharge (delta VQ) and the capacitor’s equivalent series resistance (delta VESR). These ripple components are found by: 'VQ = 'I L x D 2 x f SW x C IN and 'VESR = 2 x 'I L x R ESR where 'I L = VIN x (VOUT - VIN ) 2 x f SW x L x VOUT (7) In the typical application circuit a 1µF ceramic input capacitor works well. Since the ESR in ceramic capacitors is typically less than 5mΩ and the capacitance value is usually small, the input voltage ripple is primarily due to the capacitive discharge. With larger value capacitors such as tantalum or aluminum electrolytic the ESR can be greater than 0.5Ω. In this case the input ripple will primarily be due to the ESR. Output Capacitor Selection The LM3528’s output capacitor supplies the LED current during the boost converters on time. When the switch turns off the inductor energy is discharged through the diode supplying power to the LED’s and restoring charge to the output capacitor. This causes a sag in the output voltage during the on time and a rise in the output voltage during the off time. The output capacitor is therefore chosen to limit the output ripple to an acceptable level depending on LED or OLED panel current requirements and input/output voltage differentials. For proper operation ceramic output capacitors ranging from 1µF to 2.2µF are required. As with the input capacitor, the output voltage ripple is composed of two parts, the ripple due to capacitor discharge (delta VQ) and the ripple due to the capacitors ESR (delta VESR). For continuous conduction mode, the ripple components are found by: 'VQ = ILED u (VOUT fSW u VOUT u COUT 'VESR = RESR u where 24 VIN) 'IL = and § ILED u VOUT · + 'IL¸ ¨ VIN © ¹ VIN u (VOUT VIN) 2 u fSW u L u VOUT (8) Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Product Folder Links: LM3528 LM3528 www.ti.com SNVS513B – AUGUST 2008 – REVISED MAY 2013 Table 8 lists different manufacturers for various capacitors and their case sizes that are suitable for use with the LM3528. When configured as a dual output LED driver a 1µF output capacitor is adequate. In OLED mode for output voltages above 12V a 2.2µF output capacitor is required (see Low Output Voltage Operation (OLED) Section). Table 8. Recommended Output Capacitors Manufacturer Part Number Value Case Size Voltage Rating TDK C1608X5R1E105M 1µF 0603 25V Murata GRM39X5R105K25D539 1µF 0603 25V TDK C2012X5R1E225M 2.2µF 0805 25V Murata GRM219R61E225KA12 2.2µF 0805 25V Inductor Selection The LM3528 is designed for use with a 10µH inductor, however 22µH are suitable providing the output capacitor is increased 2×. When selecting the inductor ensure that the saturation current rating (ISAT) for the chosen inductor is high enough and the inductor is large enough such that at the maximum LED current the peak inductor current is less than the LM3528’s peak switch current limit. This is done by choosing: ISAT > 'IL = I LED VOUT + 'I L × K VIN VIN x (VOUT - VIN ) 2 x f SW x L x VOUT where , and VIN x (VOUT - VIN) L> § 2 x f SW x VOUT x ¨ ¨I PEAK - I LED _ MAX x VOUT · © ¸¸ ¹ K x VIN (9) Values for IPEAK can be found in the plot of peak current limit vs. VIN in the Typical Performance Characteristics graphs. Table 9 shows possible inductors, as well as their corresponding case size and their saturation current ratings. Table 9. Recommended Inductors Manufacture r Part Number Value Dimensions ISAT DC Resistance TDK VLF3012AT-100MR49 10µH 2.6mm×2.8mm×1mm 490mA 0.36Ω Coilcraft LPS3008-103ML 10µH 2.95mm×2.95mm×0.8mm 490mA 0.65Ω TDK VLF4012AT-100MR79 10µH 3.5mm×3.7mm×1.2mm 800mA 0.3Ω Coilcraft LPS4012-103ML 10µH 3.9mm×3.9mm×1.1mm 700mA 0.35Ω TOKO A997AS-100M 10µH 3.8mm×3.8mm×1.8mm 580mA 0.18Ω Diode Selection The output diode must have a reverse breakdown voltage greater than the maximum output voltage. The diodes average current rating should be high enough to handle the LM3528’s output current. Additionally, the diodes peak current rating must be high enough to handle the peak inductor current. Schottky diodes are recommended due to their lower forward voltage drop (0.3V to 0.5V) compared to (0.6V to 0.8V) for PN junction diodes. If a PN junction diode is used, ensure it is the ultra-fast type (trr < 50ns) to prevent excessive loss in the rectifier. For Schottky diodes the B05030WS (or equivalent) work well for most designs. See Table 10 for a list of other Schottky Diodes with similar performance. Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Product Folder Links: LM3528 25 LM3528 SNVS513B – AUGUST 2008 – REVISED MAY 2013 www.ti.com Table 10. Recommended Schottky Diodes Manufacturer Part Number Package Reverse Breakdown Voltage Average Current Rating On Semiconductor NSR0230P2T5G SOD-923 (0.8mm×0.6mm×0.4mm) 30V 200mA On Semicondcuctor NSR0230M2T5G SOD-723 (1mm×0.6mm×0.52mm) 30V 200mA On Semiconductor RB521S30T1 SOD-523 (1.2mm×0.8mm×0.6mm) 30V 200mA Diodes Inc. SDM20U30 SOD-523 (1.2mm×0.8mm×0.6mm) 30V 200mA Diodes Inc. B05030WS SOD-323 (1.6mm×1.2mm×1mm) 30V 0.5A Philips BAT760 SOD-323 (1.6mm×1.2mm×1mm) 20V 1A Output Current Range (OLED Mode) The maximum output current the LM3528 can deliver in OLED mode is limited by 4 factors (assuming continuous conduction); the peak current limit of 770mA (typical), the inductor value, the input voltage, and the output voltage. Calculate the maximum output current (IOUT_MAX) using the following equation: (IPEAK IOUT_MAX = where 'IL = 'IL) u K u VIN VOUT VIN u (VOUT VIN) 2 u fSW u L u VOUT (10) For the typical application circuit with VOUT = 18V and assuming 70% efficiency, the maximum output current at VIN = 2.7V will be approximately 70mA. At 4.2V due to the shorter on times and lower average input currents the maximum output current (at 70% efficiency) jumps to approximately 105mA. Figure 53 shows a plot of IOUT_MAX vs. VIN using the above equation, assuming 80% efficiency. In reality, factors such as current limit and efficiency will vary over VIN, temperature, and component selection. This can cause the actual IOUT_MAX to be higher or lower. Figure 53. Typical Maximum Output Current in OLED Mode (assumed 80% efficiency) Output Voltage Range (OLED Mode) The LM3528's output voltage is constrained by 2 factors. On the low end it is limited by the minimum duty cycle of 10% (assuming continuous conduction) and on the high end it is limited by the over voltage protection threshold (VOVP) of 22V (typical). In order to maintain stability when operating at different output voltages the output capacitor and inductor must be changed. Refer to Table 10 for different VOUT, COUT, and L combinations. 26 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Product Folder Links: LM3528 LM3528 www.ti.com SNVS513B – AUGUST 2008 – REVISED MAY 2013 Table 11. Component Values for Output Voltage Selection VOUT COUT L VIN Range 18V 2.2µF 10µH 2.7V to 5.5V 15V 2.2µF 10µH 2.7V to 5.5V 12V 4.7µF 10µH 2.7V to 5.5V 9V 10µF 10µH 2.7V to 5.5V 7V 10µF 4.7µH 2.7V to 5.5V 5V 22µF 4.7µH 2.7V to 4.5V Application Circuits 10 PH VOLED = 18V 20 mA 2.7V to 5.5V IN SW OVP CIN 1 PF VIO 10 k: 40 mA COUT 2.2 PF OLED Display LM3528 10 k: R2 10 k: MAIN SCL SDA R1 140 k: SUB/FB HWEN/ PGEN/GPIO GPIO Current Limiting Resistor SET PGND RSET 12.1 k: 1 M: Indicator LED OLED Panel Power Supply With Indicator LED Figure 54. LED Backlight + OLED Power Supply Layout Considerations Refer to AN-1112 SNVA009 for DSBGA package soldering The high switching frequencies and large peak currents in the LM3528 make the PCB layout a critical part of the design. The proceeding steps should be followed to ensure stable operation and proper current source regulation. 1. CIN should be located on the top layer and as close to the device as possible. The input capacitor supplies the driver currents during MOSFET switching and can have relatively large spikes. Connecting the capacitor close to the device will reduce the inductance between CIN and the LM3528 and eliminate much of the noise that can disturb the internal analog circuitry. 2. Connect the anode of the Schottky diode as close to the SW pin as possible. This reduces the inductance between the internal MOSFET and the diode and minimizes the noise generated from the discontinuous diode current and the PCB trace inductance that will add ringing at the SW node and filter through to VOUT. This is especially important in VOUT mode when designing for a stable output voltage. 3. COUT should be located on the top layer to minimize the trace lengths between the diode and PGND. Connect the positive terminal of the output capacitor (COUT+) as close as possible to the cathode of the diode. Connect the negative terminal of the output capacitor (COUT-) as close as possible to the PGND pin on the LM3528. This minimizes the inductance in series with the output capacitor and reduces the noise present at VOUT and at the PGND connection. This is important due to the large di/dt into and out of COUT. The returns for both CIN and COUT should terminate directly to the PGND pin. Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Product Folder Links: LM3528 27 LM3528 SNVS513B – AUGUST 2008 – REVISED MAY 2013 www.ti.com 4. Connect the inductor on the top layer close to the SW pin. There should be a low impedance connection from the inductor to SW due to the large DC inductor current, and at the same time the area occupied by the SW node should be small so as to reduce the capacitive coupling of the high dV/dt present at SW that can couple into nearby traces. 5. , Route the traces for RSET and the feedback divider away from the SW node to minimize the capacitance between these nodes that can couple the high dV/dt present at SW into them. Furthermore, the feedback divider and RSETshould have dedicated returns that terminate directly to the PGND pin of the device. This will minimize any shared current with COUT or CIN that can lead to instability. Avoide routing the SUB/FB node close to other traces that can see high dV/dt such as the I2C pins. The capacitive coupling on the PCB between FB and these nodes can disturb the output voltage and cause large voltage spikes at VOUT. 6. Do not connect any external capacitance to the SET pin. 7. Refer to the LM3528 Evaluation Board as a guide for proper layout. 28 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Product Folder Links: LM3528 LM3528 www.ti.com SNVS513B – AUGUST 2008 – REVISED MAY 2013 REVISION HISTORY Changes from Revision A (May 2013) to Revision B • Page Changed layout of National Data Sheet to TI format .......................................................................................................... 28 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Product Folder Links: LM3528 29 PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2020 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) LM3528TME/NOPB ACTIVE DSBGA YFQ 12 250 RoHS & Green SNAGCU Level-1-260C-UNLIM -40 to 85 SE LM3528TMX/NOPB ACTIVE DSBGA YFQ 12 3000 RoHS & Green SNAGCU Level-1-260C-UNLIM -40 to 85 SE (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of