FP7172LR-G1

FP7172 Universal High Brightness LED Driver General Description The FP7172 is an open loop, current mode, control LED driver IC. The FP7172 can be programmed to operate in either a constant frequency or constant off-time mode. It includes an 10 450V linear regulator which allows it to work from a wide range of input voltages without the need for an external low voltage supply. The FP7172 is ideally suited for buck LED drivers. Since the FP7172 operates in open loop current mode control, the controller achieves good output current regulation without the need for any loop compensation. The FP7172 is available in the small footprint SOT23-6L package to fit in space-saving PCB layout for miscellaneous application fields. Features  Switch mode controller for single switch LED drivers  Enhanced drop-in replacement to the FP7172  Open loop peak current controller  Internal 10 to 450V linear regulator  Constant frequency or constant off-time operation  Requires few external components for operation Applications  DC/DC or AC/DC LED driver applications  RGB backlighting LED driver  Back lighting of flat panel displays  General purpose constant current source  Signage and decorative LED lighting  Chargers Typical Application Circuit VIN GND CS FP7172 GATE VIN VDD RT This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 1/11 FP7172 Function Block Diagram VIN VDD POR CS + 250mV Blanking _ R Q GATE S Oscillator GND RT Pin Descriptions SOT23-6L Top View 1 GATE 2 VIN 3 AY986 GND 6 Name No. I/O Description GND 1 P GATE 2 O VIN 3 I RT 4 I VDD 5 I CS 6 I Ground return for all internal circuitry. This pin is the output GATE driver for an external N-channel power MOSFET. This pin is the input of an 10 - 450V linear regulator This pin sets the oscillator frequency. When a resistor is connected between RT and GND, the FP7172 operates in constant frequency mode. When the resistor is connected between RT and GATE, the IC operates in constant off-time mode. This is the power supply pin for all internal circuits. This pin is the current sense pin used to sense the FET current by means of an external sense resistor. CS 5 VDD 4 RT This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 2/11 FP7172 Marking Information SOT23-6L AY986 Lot Number Year Part Number Code Lot Number: Wafer lot number’s last two digits For Example: 132386TB  86 Year: Production year’s last digit Part Number Code: Part number identification code for this product. It should be always “AV”. This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 3/11 FP7172 Ordering Information Part Number Code Operating Temperature Package MOQ Description AY -25°C ~ 85°C SOT23-6L 3000EA Tape & Reel FP7172LR-G1 Absolute Maximum Ratings Parameter Symbol Power Supply Voltage VIN VDD Conditions Min. VIN to GND VDD to GND CS, GATE, RT -0.3 Typ. Max. Unit 470 V 8 V VDD-0.3V V Allowable Power Dissipation PD SOT23-6L TA≦+25°C 455 mW Junction to Ambient Thermal Resistance θJA SOT23-6L 220 °C / W Junction Temperature TJ +125 °C -25 +85 °C -40 +150 °C +260 °C Operating Temperature Storage Temperature TS SOP-8L Lead Temperature SOP-8L (soldering, 10 sec) IR Re-flow Soldering Curve This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 4/11 FP7172 Recommended Operating Conditions Parameter Symbol Supply Voltage VCC Operating Temperature Range TA Conditions Ambient Temperature Min. Typ. Max. Unit 10 450 V -25 85 °C DC Electrical Characteristics (VCC=10V, TA=25°C, unless otherwise specified) Parameter Symbol Conditions Min. Typ. Max. Unit 7.25 7.5 7.75 V 0 - 1.0 V 100 mV 6.95 V Internal Regulator Internally regulated voltage VDD Δ VDD Line regulation of VDD VIN = 10V, IDD(ext)= 0, 500pF at GATE;RT=226kΩ VIN = 10 – 450V, IDD(ext)=0, 500pF at GATE; R =226kΩ Internal Regulator Load regulation of VDD VDD undervoltage lockout threshold VDD undervoltage lockout hysteresis Δ VDD,load UVLO IDD(ext) = 0 - 1.0mA, 500pF at GATE; RT = 226kΩ VDD rising 0 6.45 Δ UVLO VDD falling 6.7 500 mV Current Sense Comparator Current sense pull-in threshold voltage Current sense blanking interval Delay to output -25°C < TA < +85°C 225 250 275 TA < +125°C 213 250 287 150 215 280 145 215 315 80 150 VCS,TH TBLANK nV 0 < TA < +85°C, VCS =VCS,TH + 50mV after TBLANK -25 < TA < +125°C, VCS = VCS,TH + 50mV after TBLANK ns tDELAY ns Oscillator Oscillator frequency RT = 1.00MΩ 20 25 30 RT = 226kΩ 80 100 120 fOSC kHz GATE Driver GATE sourcing current ISOURCE VGATE = 0V, VDD = 7.5V 165 mA 165 mA GATE sinking current ISINK VGATE = VDD, VDD = 7.5V GATE output rise time tRISE CGATE = 500pF, VDD = 7.5V 30 50 ns GATE output fall time tFALL CGATE = 500pF, VDD = 7.5V 30 50 ns This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 5/11 FP7172 Function Description Input Voltage Regulator The FP7172 can be powered directly from its VIN pin and can work from 10 - 450VDC at its VIN pin. When a voltage is applied at the VIN pin, the FP7172 maintains a constant 7.5V at the VDD pin. This voltage is used to power the IC and any external resistor dividers needed to control the IC. The VDD pin must be bypassed by a low ESR capacitor to provide a low impedance path for the high frequency current of the output GATE driver. The FP7172 can also be operated by supplying a voltage at the VDD pin greater than the internally regulated voltage. This will turn off the internal linear regulator of the IC and the FP7172 will operate directly off the voltage supplied at the VDD pin. Please note that this external voltage at the VDD pin should not exceed 8V. Although the VIN pin of the FP7172 is rated up to 450V, the actual maximum voltage that can be applied is limited by the power dissipation in the IC. For example, if an 6-pin SOT23-6L (junction to ambient thermal resistance Rθ,j-a = 220°C/ W) FP7172 draws about IIN = 2.0mA from the VIN pin, and has a maximum allowable temperature rise of the junction temperature limited to about ΔT = 100°C, the maximum voltage at the VIN pin would be: VIN ( MAX )  T 1 100 o C 1     227V o R , j  a I in 220 C / W 2mA In these cases, to operate the FP7172 from higher input voltages, a Zener diode can be added in series with the VIN pin to divert some of the power loss from the FP7172 to the Zener diode. In the above example, using a 100V zener diode will allow the circuit to easily work up to 450V. The input current drawn from the VIN pin is a sum of the 1.0mA current drawn by the internal circuit and the current drawn by the GATE driver (which in turn depends on the switching frequency and the GATE charge of the external FET). I IN  1.0mA  QG  f S In the above equation, fS is the switching frequency and QG is the GATE charge of the external FET (which can be obtained from the datasheet of the FET). This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 6/11 FP7172 Current Sense The current sense input of the FP7172 goes to the noninverting inputs of two comparators. The inverting terminal of one comparator is tied to an internal 250mV reference. The outputs of the comparators also include a 150-280ns blanking time which prevents spurious turn-offs of the external FET due to the turn-on spike normally present in peak current mode control. In rare cases, this internal blanking might not be enough to filter out the turn-on spike. In these cases, an external RC filter needs to be added between the external sense resistor (RCS) and the CS pin. Please note that the comparators are fast (with a typical 80ns response time). Hence these comparators are more susceptible to be triggered by noise than the comparators of the FP7172. A proper layout minimizing external inductances will prevent false triggering of these comparators. Oscillator The oscillator in the FP7172 is controlled by a single resistor connected at the RT pin. The equation governing the oscillator time period tOSC is given by: tOSC (us) = R T (kΩ) 20.7 If the resistor is connected between RT and GND, FP7172 operates in a constant frequency mode and the above equation determines the time-period. If the resistor is connected between RT and GATE, the FP7172 operates in a constant off-time mode and the above equation determines the off-time. This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 7/11 FP7172 Application Information The FP7172 is optimized to drive buck LED drivers using open-loop peak current mode control. This method of control enables fairly accurate LED current control without the need for high side current sensing or the design of any closed loop controllers. The IC uses very few external components. A resistor connected to the RT pin programs the frequency of operation (or the off-time). The oscillator produces pulses at regular intervals. These pulses set the SR flip-flop in the FP7172 which causes the GATE driver to turn on. The same pulses also start the blanking timer which inhibits the reset input of the SR flip flop and prevent false turn-offs due to the turn-on spike. When the FET turns on, the current through the inductor starts ramping up. This current flows through the external sense resistor RCS and produces a ramp voltage at the CS pin. The comparators are constantly comparing the CS pin voltage to the internal 250mV. Once the blanking timer is complete, the output of these comparators is allowed to reset the flip flop. When the output of either one of the two comparators goes high, the flip flop is reset and the GATE output goes low. The GATE goes low until the SR flip flop is set by the oscillator. Assuming a 30% ripple in the inductor, the current sense resistor RCS can be set using: RCS  0.25V 1.15  I LED ( A) Constant frequency peak current mode control has an inherent disadvantage – at duty cycles greater than 0.5, the control scheme goes into subharmonic oscillations. To prevent this, an artificial slope is typically added to the current sense waveform. This slope compensation scheme will affect the accuracy of the LED current in the present form. However, a constant off-time peak current control scheme does not have this problem and can easily operate at duty cycles greater then 0.5 and also gives inherent input voltage rejection making the LED current almost insensitive to input voltage variations. But, it leads to variable frequency operation and the frequency range depends greatly on the input and output voltage variation. FP7172 makes it easy to switch between the two modes of operation by changing one connection (see oscillator section). This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 8/11 FP7172 RCS Q1 D1 GND VIR to GND VIN LED L1 GND CS CVDD FP7172 GATE VDD CLED VIN RT RT CIN Suggested Layout This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 9/11 FP7172 Typical Application CLED LED D1 1uF L1 3.3mH ER2J GND Q1 CS FP7172 GATE VDD QM01N65U CIN VIN RT 4.7uF CVDD RT RCS 0.1uF 220kΩ 5Ω This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 10/11 FP7172 Package Outline SOT23-6L Unit: mm Symbols Min. (mm) Max. (mm) A 1.050 1.450 A1 0.050 0.150 A2 0.900 1.300 b 0.300 0.500 c 0.080 0.220 D 2.900 BSC E 2.800 BSC E1 1.600 BSC e 0.950 BSC e1 1.900 BSC L 0.300 L1 0.600 0.600 REF L2 0.250 BSC θ° 0° θ1° 3° 7° θ2° 6° 15° 8° Note: 1. Package dimensions are in compliance with JEDEC outline: MO-178 AB. 2. Dimension “D” does not include molding flash, protrusions or gate burrs. 3. Dimension “E1” does not include inter-lead flash or protrusions. This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product. Website: http://www.feeling-tech.com.tw Rev. 0.64 11/11