課件參考sic gan low vfangstrem led恒流源ic demo板an9911db

1、AN9911DB2Boost LED Driver with 1:3000 Dimand Excellent Current RegulationRatioGeneral DescriptionThe AN9911DB2 is an LED driver capable of driving up to twenty 100mA LEDs in series from an input of 9 16V DC. The demoboard uses robust AN9911 IC in a boost topology. The converter hasa very good initia

2、l regulation, (+/-5%), and excellent line and load regulation over the entire input and output voltage range (<+/- 1%). The full load efciency of the converter is typically greater than 85%.The AN9911DB2 is also protectedopen LED and outputshort circuit conditions. It has an excellentdimresponse,

3、with typical rise and fall times less than 2s, which will allow highdim ratios. The AN9911DB2 also features an ENABLE input which can be used to shut down the IC and allow a very small power draw from the input.The switching frequency of the 9911DB2 can be synchronized to other 9911 boards or to an

4、external 200kHz clock by connecting the clock to the SYNC pin of the 9911DB2Board Layout and Connection DiagramVINConnections:Input: The input is connected between the terminals of connector J1 as shown in the Connection Diagram.Output: The output is connected between the terminals of connector J2 a

5、s shown.Enable: To Enable to board, connect the EN pin of the connector J3 to the input voltage as shown in the Connection Diagram. This will enable the IC and a small current will be drawn from the input. However, this will not start the converter. To start the converter, connect the D pin to the V

6、DD pin of the connector J3.push-pull waveform source between terminalsD and GND ofconnector J3 as shown by the solid lines. Note that EN should be connected to the input voltage.Note: Duringdim, pin VDD of connector J3 should be leftopen. Also, thesignal must have the proper polarity with thepositiv

7、e connected to pinD of J3. Note thatND of J3 is internally connected to the return path of the input voltage.SYNC: To synchronize two or mors, connect the SYNCpins of all ths together. To synchronize the AN9911DB1 toan external 200kHz clock, connect the clock between the SYNC terminal and GND pin of

8、 terminal J3.Dim: Todim th, connect the externalNR032206A1SpecicationsInput voltage (steady state):9V 16V DCOutput LED string voltage:35V min - 80V maxOutput current:100mA +/-5%Output current ripple:10% typicalSwitching frequency:200kHzFull load efciency:87% (at 12V input)Shut down current:100A (typ

9、)Open LED:Shuts down at 92VOutput short circuit:Includeddimfrequency:1:3000 dimratio at 200HzAN9911DB2Testing The Demoboard:Normal Operation: Connect the input source and the output LEDsShort Circuit Test: When the 9911DB2 is operating in steady state, connect a jumper across the terminals of the LE

10、D string. Notice that the output current will immediately go to zero and the converter will shut down. To restart the 9911DB2, recycle the input power to the demoboard.as shown in the Connection Diagram and enable th. TheLEDs will glow with a steady intensity. Connecting an ammeter in series with th

11、e LEDs will allow measurement of the LED current. The current will be 100mA +/- 5%.Current Regulation: With the input power to the converter disconnected, change the LED string voltage within the specications mentioned. The current output of the 9911DB2 will remain very steady over the entire load r

12、ange. Vary the input voltage while the circuit is operational. The current will be regulated over the entire line range.Open LED test: Connect a voltmeter across the output terminals of the 9911DB2. Start the demoboard normally and once the LED current reaches steady state, unplug one end of the LED

13、 string from the demoboard. The output voltage will rise to about 92V and then the 9911DB2 will shut down. To restart the converter, disconnectDim: With the input voltage to thdisconnected,apply a TTL compatible, push-pull square wave signal betweenD and GND terminals of connector J3 as shown in the

14、 Connection Diagram. Turn the input voltage back on and adjustthe duty cycle and / or frequency of thedimsignal. signal. Note thatwell at 1kHzratio can be obtainedThe output current will track thedimalthough the converter operates perfectlydimfrequency, the widestdimat lower frequencies like 100 or

15、200Hz.and reconnect the input voltage (recycle the power to th).Typical Results1. Efciency: The efciency of the converter at various LED string voltages are shown in Fig.1 (measured at the nominal input voltage of 24V). Fig.2 shows the full load efciency of the converter at vary- ing input voltages.

16、 The minimum efciency of 86% for the converter occurs at 9V input and full load output.2. Current Regulation: Figs. 3 and 4 show the output current regu- lation vs. input voltage and load voltage respectively. The total cur- rent regulation (line and load combined) is found to be less than 1%.Fig. 1

17、. Efficiency vs. Output VoltageFig. 3. Output Current vs. Input VoltageFig. 4. Output Current vs. Load VoltageFig. 2. Efficiency vs. Input VoltageNR0322062Efficiency (%)Efficiency (%)Output Current (mA)Output Current (mA)Output Current vs. Output Voltage10100.510099.599Output Voltage (V)Efficiency v

18、s. Input Voltage9089888786859111315Input Voltage (V)Efficiency vs. Output Voltage9089888786853545556575Output Voltage (V)Output Current vs. Input Voltage101100.510099.5999111315Input Voltage (V)AN9911DB23. Open LED: Open LEDfor the circuit is set4. Output Short Circuit: Fig. 6 shows the waveformsat

19、92V. The waveforms in Fig. 5 shows the output voltage, drainfor output short circuit condition. The disconnected FET is turned off in less than 300ns. The rise in the output current will depend on the input voltage and the value of inductor L1. The same protec- tion will also help in protecting the

20、LEDs in case the output voltage increases beyond the LED string voltage.voltage and output current during an open LED condition. The timetaken for the over voltageto shut the IC down will de-pend on the size of the output capacitor.Output VoltageOutput VoltageOutput CurrentOutput CurrentDrain Voltag

21、e (Q1)Fig. 5: Open LED(20/div)Fig. 6: Open Short Circuit(500ns/div)5.Dim: The rise and fall transitions of the LED currentis set at 5.0s/div. The rise and fall times are less than 1.0s induringdimare shown in Figs. 7 and 8, at output volt-each case. Thus, adimratio of 1:3000 is achievable atages of

22、80V and 40V respectively. The timescale for all waveformsadimfrequency of 200Hz.diminputdiminputLED CurrentLED CurrentFig. 7a: Rise time of LED Current at 80V output (5s/div)Fig. 7b: Fall time of LED Current at 80V output (5s/div)diminputdiminputLED CurrentLED CurrentFig. 8a: Rise time of LED Curren

23、t at 40V output (5s/div)Fig. 8b: Fall time of LED Current at 40V output (5s/div)NR0322063J1BD1J2AL1212110uHB1100-13R1510kJ3DR16C1TP0610TC210kQ4C9R18Q3C4(B32529)R1 82.5kC1010kR17J1AJ3B11n100kC5R2Used to AcheiveR3 4.99kLow Standby CurrentJ10453k1uF, 16VU1Q1FDS3692REFR4J2BSYNCREFRTC6open2GATE0.1uF, 16V

24、R11R60.08, 1/4WIREFFDBKAN9911CSREFR1218.2kQ2VN2110COMPCLIMFAULTOVP6.65kIo_SNSC7Io_SNSR103.3, 1/8WC82.2nFR7openREFopenR8J3CR919.1kJ5J6J7J8J3A6.04kAN9911DB2Circuit Schematic:NR03220642.2uF, 16V2.2uF, 16VVDDVINSCGND0.33uF, 100V0.33uF, 100VAN9911DB2Top Layer:Bottom Layer:Silk Screen:NR0322065AN9911DB2Bi

25、ll of Materials2014620Item #QutyRefDesDescriptionPackageManufacturerManufacturers Part Number12C1,C22.2F, 16V X7R ceramic chip capacitorSMD1206MurataGRM31MR71C225MA35L22C4,C90.33F, 100V metal Film capacitorsThru-HoleEPCOS IncB32529C1334J31C51F, 16V X7R ceramic chip capacitorSMD0805TDK CorpC2012X7R1C

26、105K41C60.1F, 16V X7R ceramic chip capacitorSMD0805MurataGRM219R71C104KA01D51C72.2nF, 5%, 50V C0G ceramic chip capacitorSMD0805TDK CorpC2012C0G1H222J63C86.8nF, 5%, 50V C0G ceramic chip capacitorSMD0805TDK CorpC2012C0G1H682J71D1100V, 1A schottky diodeSMADiodes Inc.B1100-1382J1,J2Side Entry 2-pin male headerThru-HoleJST Sales Amer.S2B-EH91J3Side Entry 4-pin male headerThru-HoleJST Sales Amer.S4B-EH101L1220H, 2A sat, 1.5A rms inductorSMTSumidaCDRH127/LDNP-221MC111Q1100V, 4.55A N-Channel