UM1351_16 UNIONSEMI | Alldatasheet
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Technical content
Features
Low Voltage Halogen Replacement LEDs Low Voltage Industrial Lighting LED Back-Side Lighting Illuminated Signs DC/DC or AC/DC LED Driver Application General Purpose, Constant Current Source Hysteretic Control with High Side Current Sensing Integrated 35V 0.5Ω NDMOS Up to 98% Efficiency Wide Input Voltage Range: 6V to 35V ± 5% LED Current Accuracy Adjustable Constant LED Current Analog or PWM Control Signal for PWM Dimming Over Temperature, Open Circuit LED Protection Up to 1MHz Switching Frequency Pb-Free SOT89-5 and SOT23-5 Packages
http://www.union-ic.com Rev.04 Apr.2016 2/14 UM1351 Pin Configurations Top View
Ordering Information
Part Number Packaging Type Marking Code Shipping Qty UM1351Y SOT89-5 UM1351Y 1000pcs/7Inch Tape & Reel UM1351S SOT23-5 5FA 3000pcs/7Inch Tape & Reel 3 4 5LX GND VSET ISENSE VIN GND 1 2 3 UM1351Y XX XX: Week Code UM1351Y SOT89-5 LX GND VSET ISENSE VIN 3 4 1 2 3 M5FA M: Month Code UM1351S SOT23-5
http://www.union-ic.com Rev.04 Apr.2016 3/14 UM1351 Pin Description Pin Number Symbol Function UM1351Y UM1351S 1 3 LX Drain of NDMOS switch. 2 2 GND Ground (0V). 3 1 VSET Multi-function On/Off and brightness control pin: Leave floating for normal operation. Drive to voltage below 0.2V to turn off output current. Drive with DC voltage (0.3V <VSET<2.5V) to adjust output current from 12% to 100% of IOUTnom. Drive with PWM signal from open -collector or open-drain transistor, to adjust output current. Adjustment range 1% to 100% of I OUTnom for f<100kHz. Connect a capacitor from this pin to ground to increase soft-start time. (Default soft-start time= 10μs. Additional soft -start time is approximately 700μs/nF.) 4 5 ISENSE Connect resistor RS from this pin to VIN to define nominal average output current IOUTnom=0.1/RS. 5 4 VIN Input voltage (6V to 35V). Decouple to ground with 10μF or higher X7R ceramic capacitor close to device. Absolute Maximum Ratings Over operating free-air temperature (unless otherwise noted) (Note 1) Symbol Parameter Value Unit VIN Input Voltage Range -0.3 to +35 V VLX, VISENSE Voltages on LX, ISENSE -0.3 to +35 V VSET VSET Pin Voltage -0.3 to +6 V θJA Thermal Resistance (Junction to Ambient) SOT89-5 100 °C/W SOT23-5 230 TJ Maximum Junction Temperature +150 °C TSTG Storage Temperature Range -55 to +150 °C TL Maximum Lead Temperature for Soldering 5 Seconds +300 °C Note 1: These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. All voltage values are with respect to network ground terminal. Recommended Operating Conditions Symbol Parameter Min Typ Max Unit VIN Input Voltage Range 6.0 35 V TA Operating Ambient Temperature -40 85 °C TJ Operating Junction Temperature -40 150 °C
http://www.union-ic.com Rev.04 Apr.2016 4/14 UM1351
Electrical Characteristics
(VIN=16V, TA=25°C, unless otherwise noted) Symbol Parameter Test Conditions Min Typ Max Unit VIN Input Voltage Range 6 35 V ILED Output Current RS=0.33Ω 303 mA RS=0.15Ω 666 IQ Quiescent Current without Switching VSET Pin Floating, VIN=16V 430 μA ISD Shutdown Current VSET=GND, VIN=16V 30 60 μA VSENSE Mean Current Sense Threshold Voltage Measured on ISENSE Pin with Respect to VIN 95 100 105 mV VSENSE_HYS Sense Threshold Hysteresis ±15 % ISENSE ISENSE Pin Input Current VSENSE=VIN-0.1 20 μA VEN VSET Range on VSET Pin For DC Dimming 0.3 2.5 V VENON DC Voltage on VSET Pin to Enable VEN Rising 0.25 V VENOFF DC Voltage on VSET Pin to Disable VEN Falling 0.2 V RLX LX Switch On Resistance ILX=700mA 0.5 Ω ILX(leak) LX Switch Leakage Current 5 μA TSS Soft Start Time VIN=16V, CEN=1nF 700 μs FLX Operating Frequency VIN=16V, L=47μH, VOUT=9.6V (3 LEDs), ILED=700mA 350 kHz FLXmax Recommended Maximum Switch Frequency
1.0 MHz
Ton_rec (Note 2) Recommended Minimum Switch ON Time For 4% Accuracy 500 ns Max Duty Cycle 100 % DLX Recommended Duty Cycle Range 25 75 % TPD (Note 2) Internal Comparator Propagation Delay 45 ns TOTP Over Temperature Protection 150 °C TOTP_HYS Temperature Protection Hysteresis 40 °C ILXmax Peak Switch Current 0.75 1.0 A Note 2: Parameters are not tested at production, but guaranteed by design.
http://www.union-ic.com Rev.04 Apr.2016 5/14 UM1351 Function Block Diagram Rs VIN ISENSE LED VSET GND VIN EN VSET BG Regulator GM Ilimit OTPLow Voltage Detector LX Internal Enable Logic Driver Ref Typical Application Circuit Rs 0.33Ω 100μH 10μF Floating VIN(6V-35V) VIN VSET ISENSE LX UM1351
http://www.union-ic.com Rev.04 Apr.2016 6/14 UM1351 Typical Operating Characteristics 100 0 5 10 15 20 25 30 Efficiency (%) VIN (V) Efficiency vs. Vin (Rs=0.33Ω, L=100μH) 1LED 2LED 3LED 4LED 5LED 6LED 7LED 8LED 100 0 5 10 15 20 25 30 Efficiency (%) VIN (V) Efficiency vs. Vin (Rs=0.15Ω, L=47μH) 1LED 2LED 3LED 4LED 5LED 6LED 7LED 8LED 100 200 300 400 500 600 700 800 0 5 10 15 20 25 30 35 Operating Frequency (kHz) VIN (V) Operating Frequency vs. Vin (Rs=0.15Ω, L=47μH) 1LED 2LED 3LED 4LED 5LED 6LED 7LED 8LED 350 370 390 410 430 450 470 490 510 0 5 10 15 20 25 30 35 Quiescent Current (μA) VIN (V) Quiescent Current vs. Vin 0 5 10 15 20 25 30 35 Shutdown Current (μA) VIN (V) Shutdown Current vs. Vin 100 150 200 250 300 350 0 10 20 30 40 50 60 70 80 90 100 ILED (mA) Duty Cycle (%) LED Current vs. VSET Duty Cycle (Vin=16V, 3 LEDs, 100μH, Rs=0.33Ω) PWM=100Hz Efficiency vs. VIN (Rs=0.33Ω, L1=100µH) Efficiency vs. VIN (Rs=0.15Ω, L1=47µH) Operating Frequency vs. VIN (Rs=0.15Ω, L1=47µH) Quiescent Current vs. VIN Shutdown Current vs. VIN LED Current vs. VSET Duty Cycle (VIN=16V, 3 LEDs, 100µH, Rs=0.33Ω) 1LED 2LED 3LED 4LED 5LED 6LED 7LED 8LED 1LED 2LED 3LED 4LED 5LED 6LED 7LED 8LED 1LED 2LED 3LED 4LED 5LED 6LED 7LED 8LED PWM=100Hz
http://www.union-ic.com Rev.04 Apr.2016 7/14 UM1351 -20 -15 -10 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 Deviation from Nominal Set Value (%) Temperature (°C) LED Current Change vs. Temperature (L= 47μH, Rs=0.33 Ω) Vin=16V, 3 LEDs Typical Operating Characteristics (Continued) 100 150 200 250 300 350 0 0.5 1 1.5 2 2.5 3 ILED (mA) VSET (V) LED Current vs. VSET (Vin=16V, 3 LEDs, 100μH, Rs=0.33Ω) 100 120 140 0 5 10 15 20 25 30 Feedback Voltage (mV) VIN (V) Feedback Voltage vs. Vin (Vin=16V, 3 LEDs, 100μH, Rs=0.33Ω) H L 250 260 270 280 290 300 310 320 330 340 350 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100110120130 ILED (mA) Temperature (°C) LED Current vs. Temperature (L=47μH, Rs=0.33Ω) LED Current vs. VSET (VIN=16V, 3 LEDs, 100µH, Rs=0.33Ω) Feedback Voltage vs. VIN LED Current vs. Temperature (L1=47µH, Rs=0.33Ω) LED Current Change vs. Temperature (L1=47µH, Rs=0.33Ω) H L VIN=16V, 3 LEDs VIN=16V, 3 LEDs
http://www.union-ic.com Rev.04 Apr.2016 8/14 UM1351 Typical Operating Characteristics (Continued) LX ILED 5V/div 100mA/div VSET ILED 2V/div 200mA/div PWM ILED 5V/div 100mA/div Steady State Waveforms (3 LEDs, 100μH, VIN=16V, Rs=0.33Ω) Start up Waveforms Dimming Waveforms (PWM=50%, 3 LEDs, 100μH, VIN=16V, Rs=0.33Ω) 1μs/div 1ms/div 100% Duty Cycle Mode (3 LEDs, 100μH, VIN=10V, Rs=0.33Ω) 5V/div 100mA/div 500ns/div LX ILED 5μs/div
http://www.union-ic.com Rev.04 Apr.2016 9/14 UM1351 Applications Information Setting Nominal Average Output Current with External Resistor RS The nominal ave rage output current in the LED(s) is determined by the value of the external current sense resistor (RS) connected between VIN and ISENSE and is given by: IOUTnom =0.1/RS [for RS≥0.1Ω] This equation is valid when VSET pin is float ing or applied with a voltage higher than 2.5V (must be less than 5V). Actually, RS sets the maximum average current which can be adjusted to a less one by dimming. Output Current Adjustment by External DC Control Voltage The VSET pin can be driven by an external DC voltage (VEN), as shown, to adjust the output current to a value below the nominal average value defined by Rs. Rs 0.13Ω 68μH 10μF VIN(6V-35V) VIN VSET ISENSE LX UM1351 LED The average output current is given by: IOUT=(0.1*VEN)/(2.5*Rs) [for 0.3V<VEN<2.5V] Note that 100% brightness setting corresponds to: (2.5V≤VEN≤5V) Output Current Adjustment by PWM Control A Pulse Width Modulated (PWM) signal with duty cycle PWM can be applied to the VSET pin, as shown below, to adjust the output current to a value below the nominal average value set by resistor Rs: IOUT=(0.1*D)/RS (0≤D≤100%, 2.5V<Vpulse<5V) IOUT=(Vpulse*0.1*D)/(2.5*RS) (0≤D≤100%, 0.5V<Vpulse<2.5V)
http://www.union-ic.com Rev.04 Apr.2016 10/14 UM1351 Rs 0.13Ω 68μH 10μF VIN(6V-35V) VIN VSET ISENSE LX UM1351 LED PWM dimming provides reduced brightness by modulating the LED’s forward current between 0% and 100%. The LED brightness is controlled by adjusting the relative ratios of the on time to the off time. A 25% brightness level is achieved by turning the LED on at full current for 25% of one cycle. To ensure this switching process between on and off state is invisible by human eyes, the switching frequency must be greater than 100Hz. Above 100 Hz, the human eyes average the on and off times, seeing only an effective brightness that is proportional to the LED’s on -time duty cycle. The advantage of PWM dimming is that the forward current is always constant, therefore the LED color does not vary with brightness as it does with analog dimming. Pulsing the current provides precise brightness control while preserving the color purity. Capacitor Selection A low ESR capacitor should be used for input decoupling, as the ESR of this capacitor appears in series with the supply source impedance and lowers overall efficiency. This capacitor has to supply the relatively high peak current to the coil and smooth the current ripple on the input supply. A minimum value of 4.7μF is acceptable if the input source is close to the device, but higher values will improve performance at lower input voltages, especially when the source impedance is high. The input capacitor should be placed as close as possibl e to the IC. For maximum stability over temperature and voltage, capacitors with X7R, X5R, or better dielectric are recommended. Capacitors with Y5V dielectric are not suitable for decoupling in this application and should NOT be used. Inductor Selection Recommended inductor values for the UM1351 are in the range 47μH to 220μH. Higher values of inductance are recommended at higher supply voltages in order to minimize errors due to switching delays, which result in increased ripple and lower efficiency. Higher values of inductance also result in a smaller change in ou tput current over the supply voltage range. The inductor should be mounted as close to the device as possible with low resistance connections to the LX and VIN pins. The chosen coil should have a saturation current higher than the peak output current and a continuous current rating above the required mean output current. Suitable coils for the UM13 51 are listed in the table below:
http://www.union-ic.com Rev.04 Apr.2016 11/14 UM1351 Load Current Inductor Saturation Current Order Code L(μH) Size DCR (mΩ) Saturation Current (mA) Manufacturer 74408943470 47 4838 305 1100 Würth Elektronik www.we-online.com The inductor value should be chosen to maintai n operating duty cycle and switch 'on'/'off' times within the specified limits over the supply voltage and load current range. The following equations can be used as a guide. LX Switch 'On' time TON=(L1*ΔI)/(VIN-VLED-ILED*(RS+RL+RLX)) LX Switch 'Off' time TOFF=(L1*ΔI)/(VLED+VD+ILED*(RS+RL)) Where: L1 is the coil inductance (H) RL is the coil resistance (Ω) RS is the current sense resistance (Ω) ILED is the required LED current (A) ΔI is the coil peak-peak ripple current (A) {internally set to 0.3×ILED} VIN is the supply voltage (V) VLED is the total LED forward voltage (V) RLX is the switch resistance (Ω) {=0. 4Ω nominal} VD is the diode forward voltage at the required load current (V) Diode Selection For maximum efficiency and performance, the rectifier (D1) should be a fast low capacitance Schottky diode with low reverse leakage at the maximum operating voltage and temperature. They also provide better efficiency than silicon diodes, due to a combination of lower forward voltage and reduced recovery time. It is important to select parts with a peak current rating above the peak coil current and a continuous current rating higher than the maximum output load current. It is very important to consider the reverse leakage of the diode when ope rating above 85°C. Excess leakage will increase the power dissipation in the device and if close to the load may create a thermal runaway condition. The higher forward voltage and overshoot due to reverse recovery time in silicon diodes will increase the peak voltage on the LX output. If a silicon diode is used, care should be taken to ensure that the total voltage appearing on the LX pin including supply ripple, does not exceed the specified maximum value. PCB Layout Guidelines Careful PCB layout is crit ical to achieve low switching losses and stable operation. 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. Place Rsense as close as possible to the ISENSE and VIN. For better noise immunity, a Kelvin connection is strongly recommended between ISENSE and Rsense.
http://www.union-ic.com Rev.04 Apr.2016 12/14 UM1351
Package Information
L R 0.200 E e b1b L c 8°(4X) D A Side View Pin #1 ID DIMENSIONS Symbol MILLIMETERS INCHES Min Typ Max Min Typ Max b 0.32 - 0.54 0.013 - 0.021 b1 0.38 - 0.62 0.015 - 0.024 c 0.35 - 0.44 0.014 - 0.017 D1 1.40 - 1.83 0.055 - 0.072 e 1.50TYP 0.059TYP L 0.65 - 1.20 0.026 - 0.047 Land Pattern 1.80 0.60 1.60 0.75 1.50 3.101.60 5.35 4.50 4.55 NOTES: 1. Compound dimension: 4.50×2.50; 2. Unit: mm; 3. General tolerance ±0.05mm unless otherwise specified; 4. The layout is just for reference. Tape and Reel Orientation UM1351Y XX
http://www.union-ic.com Rev.04 Apr.2016 13/14 UM1351 UM1351S SOT23-5 Outline Drawing b D E e A Top View Side View 1 3 c L θ End View DIMENSIONS Symbol MILLIMETERS INCHES Min Typ Max Min Typ Max b 0.30 - 0.50 0.012 - 0.020 D 2.82 - 3.10 0.111 - 0.122 e 0.95REF 0.037REF e1 1.90REF 0.075REF L 0.30 - 0.60 0.012 - 0.024 θ 0° - 8° 0° - 8° Land Pattern 0.56 0.95 0.95 2.35 1.20 NOTES: 1. Compound dimension: 2.92×1.60; 2. Unit: mm; 3. General tolerance ±0.0 5mm unless otherwise specified; 4. The layout is just for reference. Tape and Reel Orientation M5FA
http://www.union-ic.com Rev.04 Apr.2016 14/14 UM1351 GREEN COMPLIANCE Union Semiconductor is committed to environmental excellence in all aspects of its operations including meeting or exceeding regulatory requirements with respect to the use of hazardous substances. Numerous successful programs have been implemented to reduce the use of hazardous substances and/or emissions. All Union components are compliant with the RoHS directive, which helps to support customers in their compliance with environmental directives. For more green compliance information, please visit: http://www.union-ic.com/index.aspx?cat_code=RoHSDeclaration IMPORTANT NOTICE The information in this document has been carefully revi ewed and is believed to be accurate. Nonetheless, this document is subject to change without notice. Union assumes no responsibility for any inaccuracies that may be contained in this document, and makes no commitment to update or to keep current the conta ined information, or to notify a person or organization of any update. Union reserves the right to make changes, at any time, in order to improve reliability, function or design and to attempt to supply the best product possible. Union Semiconductor, Inc Add: Unit 606, No.570 Shengxia Road, Shanghai 201210 Tel: 021-51093966 Fax: 021-51026018 Website: www.union-ic.com