UNISONIC TECHNOLOGIES CO., LTD USL1601 Preliminary CMOS IC CONSTANT CURRENT CONTROLLER FOR NON-ISOLATED BUCK LED DRIVER DESCRIPTION The UTC USL1601 is a high precision constant current non-isolated buck LED driver controller. It can operate under universal AC input, also can operate 12V~600V DC input. The UTC USL1601 integrates 600V power MOSFET, so it can use very few external components achieve excellent constant current performance. The UTC USL1601 uses high precision current sense circuit and patent method for constant current control, to achieve high precision output current and excellent line regulation. The UTC USL1601 operates in inductor current critical mode. The LED current is constant over wide range of inductance variation and the LED output voltage, so the load regulation is excellent. The UTC USL1601 operation current is 200µA only, so the auxiliary winding is not needed. It can simplify the system design and reduce the system cost. The UTC USL1601 offers rich protection functions, including LED short circuit protection, current sense resistor short circuit protection and over temperature protection. FEATURES * Inductor current critical mode, No need to compensate the inductance variation * 600V MOSFET integrated * ±3% LED current accuracy * Source driver structure, Not need the auxiliary winding for VCC ORDERING INFORMATION Ordering Number USL1601G-S08-R * LED short circuit protection * Up to 93% system efficiency * Current sense resistor short circuit protection * Over temperature protection Package SOP-8 Packing Tape Reel MARKING www.unisonic.com.tw Copyright © 2014 Unisonic Technologies Co., Ltd 1 of 6 QW-R125-033.a USL1601 Preliminary PIN CONFIGURATION PIN DESCRIPTION PIN NO. 1 2 3 4 5, 6 7, 8 PIN NAME GND LN VCC SOURCE DRAIN CS CMOS IC DESCRIPTION Ground Line compensation sense input Power supply, clamp to 12.5V by internal Zener diode Internal HV power MOSFET source Internal HV power MOSFET drain Current sense input, the sense resistor is connected from CS to ground BLOCK DIAGRAM DRAIN + VCC UVLO 8V - 7V - Restart OTP SCP SOURCE Constant Current & Logic Control LEB + Current Sense - GND Line Compensation CS 400mV +- LN UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 6 QW-R125-033.a USL1601 Preliminary CMOS IC ABSOLUTE MAXIMUM RATING (TA=25°C, unless otherwise specified) PARAMETER SYMBOL RATINGS UNIT Internal HV MOSFET Drain Voltage VDS -0.3~600 V VCC Pin Maximum Sink Current ICC_MAX 5 mA Power Dissipation (Note 2) PDMAX 0.5 W Operating Junction Temperature TJ -40~150 °C Storage Temperature Range TSTG -55~150 °C Notes: 1. Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. 2. The maximum power dissipation decrease if temperature rise, it is decided by TJMAX, θJA, and environment temperature (TA). The maximum power dissipation is the lower one between PDMAX= (TJMAX - TA)/ θJA and the number listed in the maximum table. 3. Human Body mode, 100pF capacitor discharge on 1.5KΩ resistor. RECOMMENDED OPERATION CONDITIONS PARAMETER Output LED Current RATINGS < 135 UNIT mA SYMBOL θJA RATINGS 150 UNIT °C/W THERMAL DATA PARAMETER Junction to Ambient SYMBOL ILED ELECTRICAL CHARACTERISTICS (Note 1, 2) (Unless otherwise specified, VCC=12V and TA=25°C) PARAMETER Supply Voltage Section VCC Clamping Voltage VCC Clamping Current VCC Start Up Voltage VCC Under Voltage Latch Out Hysteresis Start Up Current Operation Current Current Sense Section Current Sense Voltage Threshold Leading Edge Blanking Time Turn Off Delay Time Line Compensation Section Line Compensation Rate SYMBOL VCC_CLAMP IDD_CLAMP VCC_ST VUVLO_HYS IST IOP VCS_TH TEST CONDITIONS MIN TYP MAX 12.5 VCC Rise VCC Falling VCC=VCC_ST -0.5V 7.6 290 8.4 1 70 3 300 5 9.2 150 310 UNIT V mA V V µA mA mV TLEB TDELAY 650 100 ns ns Δ VCS/∆(VLN-VCC) -40 mV/V Over Temperature Section Thermal Shut Dow TSD 150 °C Temperature Thermal Shut Down TSD_HYS 30 °C Hysteresis Internal HV MOSFET Switch ON Resistance RDS_ON VCC=12V 10 Ω Drain to Source Voltage VDS 600 V Internal Driver Section Minimum Demagnetization Time TOFF_MIN 4 µs Maximum Demagnetization Time TOFF_MAX 130 µs Maximum Turn On Time TON_MAX 45 µs Notes: 1. Production testing of the chip is performed at 25°C 2. The maximum and minimum parameters specified are guaranteed by test, the typical value are guaranteed by design, characterization and statistical analysis UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 3 of 6 QW-R125-033.a USL1601 Preliminary CMOS IC FUNCTION DESCRIPTION The UTC USL1601 is a constant current controller, designed for driving non-isolated buck LED power supply. UTC USL1601 integrates 600V power MOSFET, and it uses patent constant current control method and source driver structure, excellent constant current characteristic is achieved with low counts components. Low cost and high efficiency of system is realized. Start up The VCC will be charged through the startup resistor when the system is powered on. When the voltage on VCC reaches the startup voltage threshold, the controller starts to switching. The VCC voltage of UTC USL1601 is clamped to 12.5V by internal Zener diode. Line Compensation The UTC USL1601 integrates line compensation function. The line voltage is sensed by the voltage difference between LN and VCC pin. And the internal reference voltage of VCS is compensated by a value proportional to the sensed line voltage. The excellent line regulation is achieved. The line compensation coefficient is given by the following equation： ∆VCS = -40×10-3× (VLN-VCC) The VCS is the reference voltage of the internal current sense comparator. The VLN is the voltage on LN pin. The VCC is the voltage on VCC pin. Constant Current Control and Output Current Setting The UTC USL1601 uses patent constant current control method, excellent constant current is achieved with low counts components. The UTC USL1601 senses the peak current in inductor cycle by cycle. The CS Pin is connected to the input of internal current comparator, and compared with the internal 300mV reference voltage. The external power MOSFET will be turned off when the CS pin voltage reaches the voltage threshold. The comparator has a 650ns LEB timer to avoid mis-trigger. The peak current in the inductor is given by: 400 IPK = (mA） RCS The RCS is the resistance of current sense resistor The current in LED can be calculated by the following equation: I ILED = PK 2 The IPK is the peak current in inductor Source Driver Structure The UTC USL1601 uses the patent source driver structure. The typical operation current is as low as 3mA, the auxiliary winding is not need. So the system design is simple and the cost is low. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 4 of 6 QW-R125-033.a USL1601 Preliminary CMOS IC FUNCTION DESCRIPTION(Cont.) Inductance Calculation The UTC USL1601 is designed to work in inductor current critical mode, the energy will be stored in the inductor when the MOSFET is turned on. The turn on time is given by: L × IPK t on = VIN - VLED The L is the inductance. The IPK is the peak current in inductor. The VIN is the input rectified voltage. The VLED is the voltage on LED. When the power MOSFET is turned off, the inductor current will decrease from the peak current to zero. The turn off time is given by: L × IPK t off = VLED The MOSFET will be turned on again when it detects the inductor current goes to zero. The inductance can be calculated by the following equation: V × ( VIN - VLED ) L = LED f × IPK × VIN The UTC USL1601 internally set the minimum off time to 4µs and maximum off time to 130µs. When the inductance is very small, the toff may goes below the minimum off time and the inductor current becomes discontinuous. So the output LED current will be smaller than the setting value. If the inductance is too large, the toff may goes beyond the maximum off time and the inductor current becomes continuous. And the output LED current will be larger than the setting value. So it’s very important to select a right inductance. The UTC USL1601 also internally set the maximum on time to 40µs. When the input voltage is very low or LED output voltage is very high, the ton may goes beyond the maximum on time. The power MOSFET will be turned off even the inductor current still below the setting value. So the output LED current will be smaller than the setting value. Protection Functions The UTC USL1601 has many protection functions, including LED short circuit protection, current sense resistor short circuit protection and over temperature protection. All of the protection functions are designed to auto-recover. The over temperature protection circuitry in the UTC USL1601 monitors the die junction temperature after start up. When the temperature rises to 150°C, the power MOSFET will be shut down immediately and maintains at switch off condition until the temperature on die falls 30°C below the thermal protection trigger point. PCB Layout The following guidelines should be followed in UTC USL1601 PCB layout: Bypass Capacitor The bypass capacitor on VCC pin should be as close as possible to the VCC and GND pins. Ground Path The power ground path for current sense should be short, and the power ground path should be separated from small signal ground path before the negative node of the bus capacitor. The Area of Power Loop The area of main current loop should be as small as possible to reduce EMI radiation. And the controller should be placed away from the heat generator, such as the power diode. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 5 of 6 QW-R125-033.a USL1601 Preliminary CMOS IC TYPICAL APPLICATION CIRCUIT AC UTC USL1601 VCC DRAIN LN DRAIN SOURCE CS GND CS UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 6 QW-R125-033.a