LT3922-1 (Rev. A)
Document overview
- Manufacturer or author: Analog Devices, Inc.
- PDF pages: 34
Technical content
Rev. AFor more information www.analog.comDocument Feedback TYPICAL APPLICATION FEATURES DESCRIPTION 36V, 2.3A Synchronous Step-Up LED Driver with 25,000:1 PWM Dimming The LT®3922-1 is a monolithic, synchronous, step-up DC/ DC converter that utilizes fixed-frequency, peak current control and provides PWM dimming for a string of LEDs. The LED current is programmed by an analog voltage or the duty cycle of pulses at the CTRL pin. The LT3922-1 will maintain ±2.5% current regulation through an external sense resistor over a wide range of output voltages. The switching frequency is programmable from 200kHz to 2MHz by an external resistor at the RT pin or by an external clock applied at the SYNC/SPRD pin. With the optional spread spectrum frequency modulation enabled, the frequency varies from 100% to 125% to reduce EMI. The LT3922-1 also includes a driver for an external high side PMOS for PWM dimming and an internal PWM signal generator for analog control of PWM dimming. When an external signal is available, the LT3922-1 can perform 25,000:1 PWM dimming with 100Hz PWM pulses. Additional features include an accurate external reference voltage for use with the CTRL and PWM pins, an LED current monitor, an accurate EN/UVLO pin threshold, open-drain fault reporting for open-circuit and short-circuit load conditions, and thermal shutdown. 30V, 333mA Boost LED Driver with 25,000:1 PWM Dimmming
APPLICATIONS
n ±2.5% LED Current Regulation n ±2% Output Voltage Regulation n 25,000:1 PWM Dimming at 100Hz n 128:1 Internal PWM Dimming n Spread Spectrum Frequency Modulation n Silent Switcher® Architecture for Low EMI n Operates in Boost, Buck Mode and Buck-Boost Mode n 2.8V to 36V Input Voltage Range n Up to 34V LED String Voltage n 2.3A, 40V Internal Switches n 200kHz to 2MHz Switching Frequency with SYNC n Analog or Duty Cycle LED Current Control n Open/Short LED Protection and Fault Indication n Thermally Enhanced 28-Lead (4mm × 5mm) QFN n AEC-Q100 Qualified for Automotive Applications n Automotive and Industrial Lighting n Machine Vision All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 7199560, 7321203, and other patents pending. VINVIN 8V TO 27V 365k 59.0k EN/UVLO OVLO VREF CTRL PWM SYNC/SPRD INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISP GND GND ISN PWMTG ISMON
39221 TA01a
33.2k 100k 51k 1nF 1µF 33µFL1, 2.2µH 300m/uni03A9 10µF 0.47µF 0.47µF 30V 333mA LED SS 45.3k 2MHz L1: WURTH 74437324022 M1: VISHAY Si2319CDS 2.2µF 10nF 4.7µF INFINITE PERSISTENCE VIN = 12V fPWM = 100Hz VPWM 2V/DIV ILED 100mA/DIV 200ns/DIV
39221 TA01b
Rev. A For more information www.analog.com PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS I SP – ISN CTRL and FB OVLO, PWM, SYNC/SPRD, and FAULT SW, BST, INTVCC, VREF, ISMON, PWMTG, RT, and RP (Note 2) Operating Junction Temperature Range (Notes 3, 4) Storage Temperature Range (Note 1) 9 10 TOP VIEW UFD PACKAGE 28-LEAD (4mm × 5mm) PLASTIC QFN θJA = 25°C/W (AS MEASURED ON DEMO BOARD DC2247A), θJC = 3.4°C/W EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB 11 12 13 28 27 26 25 GND 1SW BST INTVCC VIN EN/UVLO OVLO VREF CTRL GND VOUT PWMTG PWM RP SYNC/SPRD RT FAUL T SW SW NC NC V OUT GND ISP ISN VC FB SS ISMON 8 15 LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3922EUFD-1#PBF LT3922EUFD-1#TRPBF 39221 28-Lead (4mm × 5mm) Plastic QFN –40°C to 125°C LT3922IUFD-1#PBF LT3922IUFD-1#TRPBF 39221 28-Lead (4mm × 5mm) Plastic QFN –40°C to 125°C LT3922HUFD-1#PBF LT3922HUFD-1#TRPBF 39221 28-Lead (4mm × 5mm) Plastic QFN –40°C to 150°C AUTOMOTIVE PRODUCTS** LT3922EUFD-1#WPBF LT3922EUFD-1#WTRPBF 39221 28-Lead (4mm × 5mm) Plastic QFN –40°C to 125°C LT3922IUFD-1#WPBF LT3922IUFD-1#WTRPBF 39221 28-Lead (4mm × 5mm) Plastic QFN –40°C to 125°C LT3922HUFD-1#WPBF LT3922HUFD-1#WTRPBF 39221 28-Lead (4mm × 5mm) Plastic QFN –40°C to 150°C Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix. **Versions of this part are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. These models are designated with a #W suffix. Only the automotive grade products shown are available for use in automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for these models. ORDER INFORMATION
Rev. AFor more information www.analog.com ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VIN = 12V, VEN/UVLO = 2V unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Input Voltage Range 2.8 36 V VIN Pin Quiescent Current VEN/UVLO = 1.5V, Not Switching VEN/UVLO = 0.1V, Shutdown 2.9 4 mA µA EN /UVLO Threshold (Falling) 1.260 1.330 1.400 V EN/UVLO Rising Hysteresis 25 mV EN/UVLO Pin Current VEN/UVLO = 1.2V 2 µA Input OVLO Threshold (Rising) 1.145 1.205 1.265 V Input OVLO Falling Hysteresis 50 mV OVLO Pin Current VOVLO = 1.0V –100 100 nA Reference VREF Voltage IVREF = 10µA IVREF = 500µA l 1.97 1.985 2.03 2.015 V V VREF Pin Current Limit VREF = 0V, Current Out of Pin 3.2 mA LED Current Regulation CTRL-Off Threshold (Falling) l 200 210 220 mV CTRL-Off Rising Hysteresis 15 mV CTRL Pin Current VCTRL = 2V −100 100 nA Sense Voltage (VISP−VISN) (Analog Input) VCTRL = 2V (100%), VISP = 24V VCTRL = 0.75V (50%), VISP = 24V VCTRL = 0.3V (5%), VISP = 24V l l l 97.5 3.5 100 102.5 6.5 mV mV mV ISP Pin Current VISP = 24.1V, VISN = 24V, VCTRL = 2V 75 µA ISN Pin Current VISP = 24.1V, VISN = 24V , VCTRL = 2V 75 µA Current Error Amplifier T ransconductance V ISP = 24V 140 µA/V Duty Cycle Control of LED Current Sense Voltage (VISP−VISN) (Duty Cycle Input) CTRL Duty CTRL Duty = 37.5% (50%), VISP = 24V CTRL Duty = 15% (5%), VISP = 24V 100 101 mV mV mV CTRL Pulse Input High (VIH) 1.6 V CTRL Pulse Input Low (VIL) 0.4 V CTRL Pulse Input Frequency Range 10 200 kHz Voltage Regulation FB Regulation Voltage VCTRL = 2V l 1.175 1.200 1.225 V FB Pin Current FB in Regulation −100 100 nA Voltage Error Amplifier T ransconductance 1000 µA/V INTVCC Regulator INTVCC Voltage 2.7 3 3.3 V INTVCC Pin Current Limit VINTVCC = 0V, Current Out of Pin 20 mA
Rev. A For more information www.analog.com
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS Power Stage Peak Current Limit VIN = 3V 2.3 2.55 2.8 A Bottom Switch Minimum Off-Time l 15 25 35 ns Bottom Switch On-Resistance 140 mΩ Top Switch On-Resistance 155 mΩ Oscillator Programmed Switching Frequency (f SW) R T = 45.3k, VSYNC/SPRD = 0V RT = 499k, VSYNC/SPRD = 0V l l 1880 175 2000 200 2120 245 kHz kHz Spread Spectrum Frequency Range R T = 45.3k, VSYNC/SPRD = 3V RT = 499k, VSYNC/SPRD = 3V 1880 175 2650 306 kHz kHz R T Pin Current Limit VRT = 0V, Current Out of Pin 75 µA SYNC/SPRD Threshold (Rising) 1.4 1.5 V SYNC/SPRD Falling Hysteresis 0.2 V SYNC/SPRD Pin Current VSYNC/SPRD = 5V −100 100 nA Soft-Start SS Pin Charging Current VSS = 1V 20 µA SS Pin Discharging Current VSS = 2V 2 µA SS Lower Threshold 0.2 V SS Higher Threshold 1.7 V Fault Detection Open-Circuit Threshold (FB Rising) V ISP = VISN = 20V l 1.117 1.140 1.163 V Open-Circuit Falling Hysteresis 50 mV LED Short-Circuit Threshold (VISP − VISN) V ISP = 20V 150 mV FAUL T Pull-Down Current VFAUL T = 0.2V, VFB = 1.25V 0.8 mA FAUL T Leakage Current VFAUL T = 3V, VFB = 0.7V −100 100 nA Overvoltage Protection FB Overvoltage Threshold (Rising) l 1.240 1.266 1.292 V FB Overvoltage Falling Hysteresis 22 mV LED Current Monitor ISMON Voltage V ISP − VISN = 100mV (100%), VISP = 24V VISP − VISN = 10mV (10%), VISP = 24V 0.980 1.000 100 1.020 120 V mV P WM Driver PWMTG Gate Drive (VOUT – VPWMTG) V OUT = 20V, VPWM = 1.5V 10 11 V PWM Threshold (Rising) 1.4 V PWM Falling Hysteresis 0.2 V PWM Pin Current VPWM = 2V −100 100 nA P WM to PWMTG Propagation Delay T urn-On T urn-Off CPWMTG = 2.1nF (Connected from VOUT to PWMTG) VOUT = 20V 110 140 ns ns The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VIN = 12V, VEN/UVLO = 2V unless otherwise noted.
Rev. AFor more information www.analog.com Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Do not apply a positive or negative voltage source to these pins, otherwise permanent damage may occur. Note 3: The LT3922E-1 is guaranteed to meet performance specifications from 0°C to 125°C junction temperature. Specifications over the −40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT3922I-1 is guaranteed to meet performance specifications over the −40°C to 125°C operating junction temperature range. The LT3922H-1 is guaranteed over the −40°C to 150°C operating junction temperature range. Operating lifetime is derated at junction temperatures greater than 125°C. Note 4: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. The maximum rated junction temperature will be exceeded when this protection is active. Continuous operation above the specified absolute maximum operating junction temperature may impair device reliability or permanently damage the device. PARAMETER CONDITIONS MIN TYP MAX UNITS Internal PWM Dimming PWM Voltage for 100% PWM Dimming R P = 28.7k, VREF = 2V 2.00 V PWM Voltage for 0% PWM Dimming R P = 28.7k, VREF = 2V 0.99 V PWM Dimming Accuracy RP = 28.7k, VREF = 2V, VPWM = 1.1V RP = 28.7k, VREF = 2V, VPWM = 1.9V 7.5 87.5 10.5 90.5 13.5 93.5 P WM Dimming Frequency RP = 28.7k, RT = 45.3k, VSYNC/SPRD = 0V RP = 332k, RT = 45.3k, VSYNC/SPRD = 0V 7.34 115 7.81 122 8.28 129 kHz Hz RP Pin Current Limit VRP = 0V, Current Out of Pin 65 µA
Rev. A For more information www.analog.com TYPICAL PERFORMANCE CHARACTERISTICS VIN Shutdown Current VIN Quiescent Current INTVCC Voltage INTVCC Load Regulation VREF Voltage VREF Load Regulation EN/UVLO Thresholds EN/UVLO Pin Current OVLO Threshold VIN = 12V, TA = 25°C, unless otherwise noted. RISING FALLING TEMPERATURE (°C) –45 –20 105 130 155 1.20 1.25 1.30 1.35 1.40 1.45 1.50 EN/UVLO THRESHOLD (V)
39221 G01
V EN/UVLO = 1.2V TEMPERATURE (°C) –45 –20 105 130 155 0.50 1.00 1.50 2.00 2.50 3.00 EN/UVLO PIN CURRENT (µA)
39221 G02
TEMPERATURE (°C) –45 –20 105 130 155 1.05 1.10 1.15 1.20 1.25 1.30 1.35 OVLO THRESHOLD (V)
39221 G03
V IN = 36V V IN = 12V V IN = 2.7V TEMPERATURE (°C) –45 –20 105 130 155 0.50 1.00 1.50 2.00 2.50 V IN SHUTDOWN CURRENT (µA)
39221 G04
TEMPERATURE (°C) –45 –20 105 130 155 2.00 2.20 2.40 2.60 2.80 3.00 3.20 3.40 3.60 V IN QUIESCENT CURRENT (mA)
39221 G05
V IN = 36V V IN = 12V V IN = 2.7V TEMPERATURE (°C) –50 –25 100 125 150 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 INTV CC VOL TAGE (V)
39221 G06
V IN = 36V V IN = 12V V IN = 2.7V –40°C 25°C 125°C 150°C INTV CC LOAD CURRENT (mA) 2.80 2.85 2.90 2.95 3.00 3.05 3.10 INTV CC VOL TAGE (V)
39221 G07
TEMPERATURE (°C) –50 –25 100 125 150 1.97 1.98 1.99 2.00 2.01 2.02 V REF VOL TAGE (V)
39221 G08
V REF LOAD CURRENT (µA) 200 400 600 800 1000 1.97 1.98 1.99 2.00 2.01 2.02 V REF VOL TAGE (V)
39221 G09
–40°C 25°C 125°C 150°C
Rev. AFor more information www.analog.com TYPICAL PERFORMANCE CHARACTERISTICS RT and RP Pin Current Limits Soft-Start Currents Soft-Start Thresholds Switching Frequency Internal PWM Frequency Internal PWM Duty Cycle VREF Line Regulation INTVCC and VREF UVLO Falling Thresholds Minimum Off Time VIN = 12V, TA = 25°C, unless otherwise noted. V IN VOL TAGE (V) 1.990 1.992 1.994 1.996 1.998 2.000 2.002 2.004 2.006 2.008 2.010 VOL TAGE (V)
39221 G10
V REF UVLO TEMPERATURE (°C) –45 –20 105 130 155 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 THRESHOLD VOL TAGE (V)
39221 G11
TEMPERATURE (°C) –45 –20 105 130 155 MINIMUM OFF TIME (ns)
39221 G12
TEMPERATURE (°C) –45 –20 105 130 155 MAXIMUM PIN CURRENT (µA)
39221 G13
TEMPERATURE (°C) –45 –20 105 130 155 CURRENT (µA)
39221 G14
TEMPERATURE (°C) –45 –20 105 130 155 0.4 0.8 1.2 1.6 2.0 THRESHOLD VOL TAGE (V)
39221 G15
R T = 45.3k R T = 499k TEMPERATURE (°C) –45 –20 105 130 155 1400 1500 1600 1700 1800 1900 2000 2100 2200 180 190 200 210 220 230 240 250 260 SWITCHING FREQUENCY (kHz)
39221 G16
R T = 45.3k R P = 28.7k R P = 332k TEMPERATURE (°C) –45 –20 105 130 155 6400 6784 7168 7552 7936 8320 110 116 122 128 134 140 INTERNAL PWM FREQUENCY (Hz)
39221 G17
R T = 45.3k R P = 332k TEMPERATURE (°C) –45 –20 105 130 155 10.0 10.1 10.2 10.3 10.4 10.5 INTERNAL PWM DUTY CYCLE (%)
39221 G18
18.2k 22.1k
Rev. A For more information www.analog.com TYPICAL PERFORMANCE CHARACTERISTICS LED Current (100% Regulation) LED Current (5% Regulation) ISMON Voltage Peak SW Current Limit LED Current Line Regulation LED Current vs VOUT LED Current (Analog CTRL) LED Current (Digital CTRL) LED Voltage Limit VIN = 12V, TA = 25°C, unless otherwise noted. V CTRL (V) 0.25 0.50 0.75 1.25 1.50 1.75 100 125 V ISP – V ISN (mV)
39221 G19
PULSE FREQUENCY AT CTRL PIN = 20kHz D CTRL (%) 12.5 37.5 62.5 87.5 100 100 125 V ISP – V ISN (mV)
39221 G20
V FB (V) 1.17 1.18 1.19 1.20 1.21 1.22 100 125 V ISP – V ISN (mV)
39221 G21
VCTRL = 2V N = 355 V CTRL = 2V V ISP = 24V 150°C 25°C –40°C ISP–ISN VOL TAGE (mV) 98.6 99.3 100 100.7 101.4 100 150 200 250 300 350 NUMBER OF UNITS
39221 G22
N = 355 V CTRL = 0.3V V ISP = 24V 150°C 25°C –40°C ISP–ISN VOL TAGE (mV) 4.2 4.6 5.4 5.8 120 160 200 NUMBER OF UNITS
39221 G23
–40°C 25°C 125°C V ISP – V ISN (mV) 100 200 400 600 800 1000 ISMON (mV)
39221 G24
f SW = 2MHz R SNS = 0.3/uni03A9
11 LEDs (VOUT ~33V)
V IN (V) 100 150 200 250 300 350 400 I LED (mA)
39221 G26
f SW = 2MHz VIN = 8V R SNS = 0.3/uni03A9 R FB_TOP = 1M R FB_BOT = 34.8k V FB OVERVOL TAGE PROTECTION LIMITED V OUT (V) 100 150 200 250 300 350 400 I LED (mA)
39221 G27
f SW = 2MHz L = 4.7µH
10 LEDs (V
~ 30V)
5 LEDs (V
~ 15V) DUTY CYCLE (%) 100 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 PEAK SW CURRENT (A)
39221 G25
Rev. AFor more information www.analog.com TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs VIN Efficiency vs ILED Regulated FB Voltage PWMTG ON Voltage PWM Driver Propagation Delay FB OVLO Threshold FB OPENLED Threshold VISP – VISN SHORTLED Threshold Power Switch On-Resistance VIN = 12V, TA = 25°C, unless otherwise noted. RISING FALLING TEMPERATURE (°C) –45 –20 105 130 155 0.90 0.95 1.00 1.05 1.10 1.15 1.20 FB OPENLED THRESHOLD (V)
39221 G28
TEMPERATURE (°C) –45 –20 105 130 155 120 130 140 150 160 170 180 V ISP – V ISN SHORTLED THRESHOLD (mV)
39221 G29
TEMPERATURE (°C) –45 –20 105 130 155 100 150 200 250 300 350 POWER SWITCH ON–RESISTANCE (m/uni03A9)
39221 G30
I LED = 400mA
11 LEDs (V
~ 33V) f SW = 400kHz f SW = 2MHz V IN (V) 100 EFFICIENCY (%)
39221 G31
V IN = 12V f SW = 2MHz
6 LED (V
~ 18V)
9 LED (V
~ 27V)
12 LED (V
~ 36V) I LED (mA) 200 400 600 800 1000 100 EFFICIENCY (%)
39221 G32
TEMPERATURE (°C) –45 –20 105 130 155 1.18 1.19 1.20 1.21 1.22 1.23 FB VOL TAGE (V)
39221 G33
TEMPERATURE (°C) –45 –20 105 130 155 V OUT – V PWMTG (V)
39221 G34
TEMPERATURE (°C) –45 –20 105 130 155 1.18 1.21 1.24 1.27 1.30 1.33 FB OVLO THRESHOLD VOL TAGE (V)
39221 G36
C PWMTG = 2.2nF (C0G type) TURN OFF TURN ON TEMPERATURE (°C) –45 –20 105 130 155 120 160 200 PROPAGATION DELAY (ns)
39221 G35
Rev. A For more information www.analog.com TYPICAL PERFORMANCE CHARACTERISTICS Internal PWM Duty Cycle (90%) Input Voltage T ransient Response Input Voltage T ransient Response Turn ON and OFF Performance Start-Up with 10% Internal PWM Start-Up with 50% Internal PWM C/10 Threshold Case Temperature Rise Internal PWM Duty Cycle (10%) VIN = 12V, TA = 25°C, unless otherwise noted. TEMPERATURE (°C) –45 –20 105 130 155 V ISP – V ISN C/10 THRESHOLD (mV)
39221 G37
V LED = 30V I LED = 333mA T ROOM = 25°C f SW = 2MHz f SW = 400kHz V IN (V) CASE TEMPERATURE RISE (°C)
39221 G38
N = 359 150°C 25°C –40°C PWM DUTY CYCLE (%) 8.6 9.4 10.2 11.0 11.8 100 150 200 250 300 350 NUMBER OF UNITS
39221 G39
N = 359 150°C 25°C –40°C PWM DUTY CYCLE (%) 90.2 90.6 91.4 92.2 93.0 93.4 100 150 200 250 300
39221 G40
6.5V to 18V INPUT VOL TAGE TRANSIENT VLED = 30V I LED = 333mA 5ms/DIV I LED 100mA/DIV V IN 5V/DIV
39221 G41
18V to 6.5V INPUT VOL TAGE TRANSIENT I LED = 333mA 5ms/DIV I LED 100mA/DIV V IN 5V/DIV
39221 G42
VLED = 30V FRONT PAGE APPLICATION I LED = 333mA 500µs/DIV I LED 100mA/DIV V IN 10V/DIV
39221 G43
VLED = 30V FRONT PAGE APPLICATION WITH PWM = 1.1V I LED = 333mA 5ms/DIV I LED 100mA/DIV V IN 10V/DIV V OUT 10V/DIV
39221 G44
VLED = 30V RP = 332k TO GND FRONT PAGE APPLICATION WITH PWM = 1.5V I LED = 333mA 5ms/DIV I LED 100mA/DIV V IN 10V/DIV V OUT 10V/DIV
39221 G45
VLED = 30V RP = 332k TO GND
Rev. AFor more information www.analog.com PIN FUNCTIONS SW: Switch Pins. These pins are internally connected to the power devices and drivers. They should always be tied together. In normal operation, the voltage of these pins will switch between the output voltage and zero at the programmed frequency. Do not force any voltage on these pins. BST: Boost Pin. This pin supplies the top power switch GATE driver. Connect a 33nF capacitor between this pin and SW close to the package. An internal diode from INTV CC to BST will charge the capacitor when the SW pin switches low. INTVCC: Internally Regulated, Low-Voltage Supply Pin. This pin provides the power for the converter switch GATE drivers. Do not force any voltage on this pin. Place a 2.2µF bypass capacitor to GND close to the package. V IN: Input Voltage Pin. This pin supplies power to the internal, high-performance analog circuitry. Connect a bypass capacitor between this pin and GND. EN/UVLO: Enable and Undervoltage Lockout Pin. A volt- age at this pin greater than 1.33V will enable switching, and a voltage less than 0.1V is guaranteed to shut down the internal current bias and sub-regulators. A resistor network between this pin and ground can be used to set the pin voltage and automatically lockout the part when V IN is below a certain level. No internal components pull up or down on this pin, so it requires an external voltage bias for normal operation. This pin may be tied directly to V IN. OVLO: Input Overvoltage Lockout Pin. When the voltage at this pin rises above 1.205V, the system disables switch- ing and resets the soft-start capacitor. Do not leave this pin open . Tie this pin to GND when the OVLO function is not used. VREF: Reference Voltage Pin. This pin provides a buffered 2V reference capable of 3mA drive. It can be used to supply resistor networks for setting the voltages at the CTRL and PWM pins. Bypass with a 1μF capacitor to GND. CTRL: Control Pin. An analog voltage from 250mV to 1.25V at this pin programs the regulated voltage between ISP and ISN (and therefore, the regulated current supplied to the load). Alternatively, a digital pulse at this pin with duty cycle from 12.5% to 62.5% can be used to program the regulated voltage. Below 200mV or 10% duty cycle, the CTRL pin voltage disables switching. For more detail, see Typical Performance Characteristics and Applications Information sections. ISP: Positive Current Sense Pin. This pin is one of the inputs to the internal current sense error amplifier. It should be connected to the positive side of the external sense resis- tor. Use Kelvin connection for accurate current sensing. ISN : Negative Current Sense Pin. This pin is one of the inputs to the internal current sense error amplifier. It should be connected to the negative side of the external sense resistor. Use Kelvin connection for accurate cur - rent sensing. V C: Compensation Pin. A resistor and capacitor connected in series from this pin to GND stabilize the current and voltage regulation. Typical resistor and capacitor values are from 0k to 100k and from 0.1nF to 10nF, respectively. FB: Feedback Pin. When the voltage at this pin is near 1.2V the regulated current is automatically reduced from the programmed value. A resistor network between this pin and V OUT can be used to set a limit for the output voltage. If the voltage at the FB pin reaches 1.266V, a FB overvolt- age lockout comparator disables switching. SS : Soft-Start Pin. At startup and recovery from fault conditions, a 20μA current charges the capacitor and the FB voltage tracks the rising voltage at this pin until the load current reaches its programmed level. Typical values for the capacitor are 10nF to 100nF. Using a single resistor from SS to INTV CC, the LT3922-1 can be set in two dif - ferent fault modes for the shorted LED conditions: hiccup no resistor) and latchoff (100k). Refer to the Applications Information section for a detailed explanation. ISMON: Output Current Monitoring Pin. This pin provides a buffered voltage output equal to 10mV for every 1mV between ISP and ISN.
Rev. A For more information www.analog.com PIN FUNCTIONS FAUL T: Fault Pin. Connect to INTVCC through a resistance of 100k. An internal switch pulls this pin low when any of following conditions happen: Open LED : VFB > 1.14V and (VISP – VISN) < 10mV Shorted LED (VISP – VISN) > 150mV for more than 300us, or (VISP – VISN) > 700mV (typical), or VOUT < (VIN – 2V) RT: Timing Resistor Pin. A resistor from this pin to GND programs the switching frequency between 200kHz and 2MHz. Do not leave this pin open. SYNC/SPRD: Synchronization Pin. To override the pro - grammed switching frequency, drive this pin with an external clock having a frequency between 200kHz and 2MHz. Even when using the external clock, select an R T resistor that corresponds to the desired switching fre - quency. Tie the pin to INTVCC to enable Spread Spectrum Frequency Modulation. This pin should be tied to GND when not in use. RP: PWM Resistor Pin. Connect a resistor from this pin to GND to set the frequency of the internal PWM signal. Do not use a resistor larger than 1MΩ. If using an external PWM pulse for LED dimming, tie this pin to GND. Refer to the Applications Information section for a detailed explanation. PWM: PWM Input Pin. With the RP pin tied to GND, drive this pin with a digital pulse to control PWM dimming of the LEDs. Alternatively, when using a resistor on the RP pin to GND, set the voltage of this pin between 1V and 2V to generate an internal pulse with duty cycle between 0% and 100%. When using an analog signal, place a 1µF bypass capacitor between this pin and GND. Tie this pin high when PWM dimming is not required. PWMTG: PWM Driver Output Pin. This pin can drive the gate of an external high-side PMOS device for PWM dim- ming of LEDs. Do not force any voltage on this pin. V OUT: Output Pins. Connect to the output and place output capacitors between these pins and GND as close as pos- sible to the package. Refer to the Applications Information section for the recommended capacitor placements GND (Pin 22, 23, Exposed Pad Pin 29): Ground Pins. All GND pins must be soldered to the board ground plane. NC: No Connect Pins. These pins can be left open or con- nected to the ground.
Rev. AFor more information www.analog.com BLOCK DIAGRAM 3 282 27 1 INTERNAL VCC REGULATOR UVLO AND OVLO 2V REFERENCE 59.0k 10µF VIN 2.2µF 33nF 4.7µH SYNCHRONOUS CONTROLLER S R Q 1µF 356k EN/UVLO VIN INTVCC BST MTSW MBSW 200m/uni03A9 SW OVLO VOUT GNDVREF SYNC/SPRD CTRL 200kHz TO 2MHz OSCILLATOR GND (EXPOSED PAD) 0.47µF 4.7µF VOUT ISN 39221 BD ISP FB 0.47µF RT SS 25 26 N/C N/C VC RP 1.4V 1.2V 20µA 2µA 45.3k 33.2k 2.5k 100k 2.5k VOUT – 10V REGULATOR INTERNAL PWM SIGNAL SOFT-START AND LED FAUL T CONTROL gm = 140µA/V CURRENT REGULATION AMPLIFIER V/I CONVERTER gm = 1000µA/V VOL TAGE REGULATION AMPLIFIER PEAK CURRENT COMPARATOR 1.25V 0.25V PWMTG DRIVER PWM PWMTG ISMON FAUL T INTVCC 10× CONTROL BUFFER 25k A/D DETECTOR 1nF 10nF 10k
Rev. A For more information www.analog.com OPERATION The LT3922-1 is a step-up LED driver that utilizes a fixed- frequency peak current control to accurately regulate the current through a string of LEDs. Low EMI performance is realized with the LT3922-1's Silent Switcher architecture, which employs magnetic field cancellation techniques to minimize electromagnetic interference. The LT3922-1 includes two power switches, their drivers, and a diode for providing power to the top switch driver. The switches connect the external inductor terminal connected to the SW pin alternately to the ground and then to the output OUT). The inductor current rises and falls accordingly and the peak current can be regulated through the combined effect of the other circuit blocks. The synchronous controller ensures the power switches do not conduct at the same time, and a programmable oscillator turns on the bottom switch at the beginning of each switching cycle. The frequency of this oscillator is set by an external resistor at the RT pin and can be overrid - den by external pulses at the SYNC/SPRD pin. The SYNC/ SPRD pin can also be used to command spread spectrum frequency modulation (SSFM). The bottom switch is turned off by the peak current com- parator which waits during the on-time for the inductor current to exceed the target set by the voltage at the V C pin. This target is modified by a signal from the oscillator which stabilizes the inductor current. A network of pas - sive components at the V C pin is necessary to stabilize this regulation loop. The inductor current is derived from the desired LED current programmed by the voltage at the CTRL pin. The analog-to-digital detector and the control buffer convert either a DC voltage or duty cycle of pulses at the CTRL pin into the input for the current regulation amplifier. The other input to this amplifier comes from the ISP and ISN pin voltages. An external current sense resistor between these pins should be placed in series with the string of LEDs such that the voltage across it provides the feedback to regulate the LED current. The current regulation ampli- fier then compares the actual LED current to the desired LED current and adjusts V C as necessary. The voltage regulation amplifier overrides the current regulation amplifier when the FB pin voltage is higher than an internal 1.2V reference. An external resistor network from the LED string to the FB pin provides an indication of the LED string voltage and allows the voltage amplifier to prevent overvoltage of the LED string. The ISP, ISN, and FB pin voltages are also monitored to detect fault conditions like open and short circuits, which are then reported by pulling FAUL T pin low. The response to a fault can be selected either to try hiccup restarts or to latchoff by the choice of an external resistor connected to the SS pin. Refer to the Applications Information section for a detailed explanation of fault responses. Finally, pulse-width modulation (PWM) of the LED current is achieved by turning on and off an external PMOS switch between the V OUT and the string of LEDs. An external pulse at the PWM pin controls the state of the PWM driver or a DC voltage at the PWM pin dictates the duty ratio of an internal PWM pulse, whose frequency is programmed with an external resistor at the RP pin. The proprietary circuits of the LT3922-1 ensures a rapid recovery of the LED current pulses for PWM. APPLICATIONS INFORMATION The following is a guide to selecting the external com - ponents and configuring the LT 3922-1 according to the requirements of an application. Programming LED Current with the CTRL Pin The primary function of the LT3922-1 is to regulate the current in a string of LEDs. This current should pass through a series current sense resistor. The voltage across this resistor is sensed by the current regulation amplifier through the ISP and ISN pins and regulated to a level pro- grammed by the CTRL pin. The maximum resistor voltage that can be programmed is 100mV which corresponds to 1A through the LED string when a 100mΩ current sense resistor is used. To allow for this maximum current, the CTRL pin may be connected directly to the V REF pin which provides
pin voltages less than 200mV. by a resistor connected between the RT pin and GND. Table 1. Higher frequencies allow for smaller external Table 1. RT Resistance Range Figure 1. Analog CTRL Range Figure 2. Duty Cycle CTRL Range Figure 3. Setting CTRL with NTC Resistors
39221 F01
39221 F02
39221 F03
measurements are with select typical application circuits. Figure 4. Typical Conducted Peak EMI of the LT3922-1 with should correspond to the frequency of the external clock. T resistor to set the frequency. SSFM is required, connect SYNC/SPRD to GND. various standard industrial tests related to interference.
39221 F04
assuming 90% efficiency for the given conditions. are recommended sources of inductors. Table 2. Inductor Manufacturers capacitor types over wide voltage and temperature ranges. Technology Application Note 88 for more information. Table 3. Capacitor Manufacturers Note 76 for more information. capacitor types over wide voltage and temperature ranges. OUT should be bypassed with three capacitors. mended for typical applications.
Figure 5. Placement of Output Capacitors
39221 F05
Table 4. PMOS Manufacturers
Table 5. Internal PWM Dimming Frequencies capacitor near PWM pin to ground. 10% of the full-scale current. Figure 6. ISMON Filter Configuration Figure 7. FB Resistor Configuration higher as there are no limits on the maximum PWM period. 10k resistor would limit the ripple on ISMON to 1%. the output voltage and the FB pin as shown in Figure 7.
39221 F06
39221 F07
Figure 8. FAUL T Resistor Configuration the 1.266V FB overvoltage lockout threshold. than 40V when the FB voltage is 1.266V.
39221 F08
when the LEDs are conducting a large current. held low until the part successfully restarts.
Figure 10. Fault Responses: (a) Latchoff and (b) Hiccup Figure 11. EN/UVLO Threshold and Hysteresis Voltages operating range of VIN voltage. old can be accurately set by an external resistor divider. threshold and the rising hysteresis voltages in LT3922-1.
39221 F10
Figure 9. SS Capacitor and Resistor Configuration
39221 F09
drive the LED at the commanded current level.
39221 F11
Figure 12. OVLO Threshold and Hysteresis Voltages Figure 13. EN/UVLO–OVLO Threshold and Hysteresis Voltages voltage is below the threshold. compromised board design, θJA could be 40°C/W or higher. connection for all of the other components separate. the second layer dissipates heat, but also reduces noise. demo board layout of the LT3922-1 for more information. single resistor string consisting of three series resistors. hysteresis voltages for EN/UVLO and OVLO. used. Do not leave these pins open.
39221 F12
39221 F13
Rev. AFor more information www.analog.com TYPICAL APPLICATIONS 2MHz, 93% Efficient 10W (30V, 333mA) Boost LED Driver Efficiency vs VIN 100:1 External PWM Dimming VINVIN 8V TO 27V 365k 59.0k 100k EN/UVLO OVLO VREF CTRLANALOG DIM PWM DIM PWM SYNC/SPRD INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISP GND GND ISN PWMTG ISMON
39221 TA02a
33.2k 100k 10k 1nF 1µF 33nFL1, 4.7µH 300m/uni03A9 4.7µF 0.47µF 0.47µF 30V 333mA LED SS 45.3k 2MHz 2.2µF 10nF 4.7µF V LED = 30V f SW = 2MHz 100% PWM DUTY CYCLE V IN (V) 100 EFFICIENCY (%)
39221 TA02b
VIN = 12V fPWM = 100Hz 20µs/DIV VPWM 2V/DIV ILED 100mA/DIV
39221 TA02c
Rev. A For more information www.analog.com TYPICAL APPLICATIONS 333mA Boost LED Driver Using Internal PWM and Analog CTRL Dimming 128:1 Internal PWM Dimming 128:1 Internal PWM with 20:1 Analog CTRL Dimming 10:1 Internal PWM Dimming 10:1 Internal PWM with 20:1 Analog CTRL Dimming VINVIN 8V TO 27V 365k 59.0k EN/UVLO OVLO VREF PWM CTRLVCTRL SYNC/SPRD INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISP GND GND ISN PWMTG ISMON
39221 TA03a
33.2k 100k 97.6k 100k 10k 1nF 1µF 0.1µF (OPTION) 33nFL1 4.7µH 300m/uni03A9 4.7µF 0.47µF 0.47µF 30V 333mA LED SS 45.3k 2MHz 332k 122Hz 10nF 2.2µF L1: WURTH 74437324047 M1: VISHAY Si2319CDS 4.7µF 10µs/DIV ILED 100mA/DIV
39221 TA03b
VCTRL = 2V VIN = 12V fPWM = 122Hz 200µs/DIV ILED 100mA/DIV
39221 TA03c
VCTRL = 2V VIN = 12V fPWM = 122Hz 10µs/DIV ILED 10mA/DIV
39221 TA03d
VCTRL = 0.3V VIN = 12V fPWM = 122Hz 200µs/DIV ILED 10mA/DIV
39221 TA03e
VCTRL = 0.3V VIN = 12V fPWM = 122Hz
Rev. AFor more information www.analog.com TYPICAL APPLICATIONS 333mA Boost LED Driver Using External PWM Dimming and SSFM 122Hz 10:1 External PWM Dimming with and without SSFM 2ms/DIV ILED (SSFM) 200mA/DIV ILED (NO SSFM) 200mA/DIV
39221 TA04b
4.7µF 365k 59.0k EN/UVLO OVLO VREF PWM CTRL SYNC/SPRD SSFM INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISP GND GND ISN PWMTG ISMON
39221 TA04a
33.2k 100k 10k 1nF 1µF 33nFL1 4.7µH 300m/uni03A9 4.7µF 0.47µF 0.47µF 30V 333mA LED SS 45.3k 2MHz10nF 2.2µF L1: WURTH 74437324047 M1: VISHAY Si2319CDS
Rev. A For more information www.analog.com TYPICAL APPLICATIONS Low EMI 400kHz, 96% Efficient 10W (30V, 333mA) Boost LED Driver with SSFM Efficiency vs VIN Peak Radiated EMI Performance (CISPR25) Average Radiated EMI Performance (CISPR25) V LED = 30V f SW = 400kHz WITHOUT EMI FIL TERS WITH EMI FIL TERS V IN (V) 100 EFFICIENCY (%)
39221 TA05b
27V 4.7µF 365k 59.0k EN/UVLO OVLO VREF PWMPWM DIM ANALOG DIM CTRL SYNC/SPRD INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISP GND GND ISN PWMTG ISMON
39221 TA05a
33.2k 100k 10k 10µF 0.1µF 0402 33µF 1nF 1µF 33nFL1 22µH 300m/uni03A9 4.7µF 2.2µF 0.47µF 0.47µF FB2 OUTPUT EMI FIL TER INPUT EMI FIL TER FB1 30V 333mA LED SS 249k 400kHz 10nF 2.2µF L1: COILCRAFT XAL5050-223MEB M1: VISHAY Si2319CDS FB1: WURTH 742792040 FB2: WURTH 742792097 D1: NXP PMEG4010CEJ 0402 0.1µF CLASS 5 PEAK LIMIT L T3922-1 400kHz f SW PEAK EMI FREQUENCY (MHz) 100 200 300 400 500 600 700 800 900 1000 –15 –10 AMPLITUDE (dBµV/m)
39221 TA05c
FREQUENCY (MHz) 100 200 300 400 500 600 700 800 900 1000 –15 –10 AMPLITUDE (dBµV/m)
39221 TA05d
Rev. AFor more information www.analog.com TYPICAL APPLICATIONS 500mA Boost LED Driver Using Pulse Duty Cycle CTRL Input VCTRL Duty Cycle Stepped from 15% to 75% VCTRL Duty Cycle Stepped from 75% to 15% 1ms/DIV ILED 200mA/DIV VCTRL 2V/DIV
39221 TA06b
39221 TA06c
4.7µF 348k 84.5k EN/UVLO OVLO VREF CTRL PWM SYNC/SPRD 3V , 10kHz PULSE INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISP GND GND ISN PWMTG ISMON
39221 TA06a
33.2k 100k 10k 1nF 1µF 33nFL1 6.8µH 200m/uni03A9 4.7µF 0.47µF 0.47µF 24V 500mA LED SS 45.3k 2MHz 10nF 2.2µF L1: WURTH 74437324068 M1: VISHAY Si2319CDS
Rev. A For more information www.analog.com Efficiency vs VIN TYPICAL APPLICATIONS 2MHz, 95% Efficient 15W (15V, 1A) Buck Mode LED Driver VINVIN 20V TO 36V VIN 22V TO 36V 33µF 51.1k 34.8k EN/UVLO OVLO SYNC/SPRD INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISP GND GND ISN PWMTG ISMON
39221 TA07a
33.2k 100k 1µF 4.7nF 33nF 4.7µH 100m/uni03A9 22µF 0.47µF 0.47µF 15V LED SS 45.3k 2MHz100nF 2.2µF L1: WURTH 74437324047 M1: VISHAY Si2319CDS Q1: ZETEX FMMT591A 20k 20k VREF PWMPWM DIM ANALOG DIM CTRL 100k1µF V IN (V) 100 EFFICIENCY (%)
39221 TA07b
Rev. AFor more information www.analog.com TYPICAL APPLICATIONS Efficiency I LOAD (mA) 100 200 300 400 500 100 EFFICIENCY (%)
39221 TA08b
500mA, 5V to 12V Boost Converter with Accurate Input Current Limit VIN VIN 2.2µF 121k 150k EN/UVLO OVLO INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISN GND GND ISP PWMTG ISMON
39221 TA08a
60.4k 100k 10k 1nF 33nFL1 4.7µH 10µF VOUT 12V 500mA0.47µF 0.47µF SS 45.3k 2MHz 10nF 2.2µF 56m/uni03A9 L1: WURTH 744316470 SYNC/SPRD VREF PWMPWM DIM ANALOG DIM CTRL 100k1µF
Rev. A For more information www.analog.com TYPICAL APPLICATIONS Shorted LED Robust Boost LED Driver Shorted LED Protection without RSS: Hiccup Mode Shorted LED Protection with RSS: Latchoff Mode 20ms/DIV ILED 1A/DIV VPWMTG 20V/DIV VSS 2V/DIV VFAUL TB 2V/DIV
39221 TA09b
39221 TA09c
4.7µF 226k 80.6k EN/UVLO OVLO INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISP GND GND ISN PWMTG ISMON
39221 TA09a
33.2k 100k 10k 1nF 33nFL1 4.7µH M1 D1 200m/uni03A9 4.7µF 0.47µF 0.47µF 21V 500mA LED SS 45.3k 2MHz RSS 100k OPTIONAL 332k 122Hz 10nF2.2µF L1: WURTH 74437324047 M1: VISHAY Si2319CDS D1: NXP PMEG4010CEJ SYNC/SPRD VREF PWMPWM DIM ANALOG DIM CTRL 100k1µF
Rev. AFor more information www.analog.com TYPICAL APPLICATIONS 2MHz, 88% Efficient 6.25W (12.5V, 500mA) Buck-Boost Mode LED Driver Efficiency vs VIN VIN VIN 6V TO 18V EN/UVLO OVLO INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISP GND GND ISN PWMTG ISMON
39221 TA10a
1µF 1nF C4, 33nFL1 4.7µH 0.2/uni03A9 C11 0.47µF C10 0.47µF 12.5V 500mA LED SS 45.3k 2MHz 10nF 2.2µF L1: WURTH 7443551470 M1: VISHAY Si2319DS Q1: ZETEX FMMT591A SYNC/SPRD VREF PWM CTRL 1µF 100k 10µF 33µF 39.2k 249k 20k R5 20k 10µF V IN (V) 100 EFFICIENCY (%)
39221 TA10b
Rev. A For more information www.analog.com PACKAGE DESCRIPTION 4.00 ±0.10 (2 SIDES)
2.50 REF
5.00 ±0.10 (2 SIDES) NOTE: 1. DRAWING PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGHD-3). 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT , SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONL Y A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE PIN 1 TOP MARK (NOTE 6) 0.40 ±0.10 27 28 BOTTOM VIEW—EXPOSED PAD
3.50 REF
0.75 ±0.05 R = 0.115 TYP R = 0.05 TYP PIN 1 NOTCH R = 0.20 OR 0.35 × 45° CHAMFER 0.25 ±0.05
0.50 BSC
0.200 REF
0.00 – 0.05 (UFD28) QFN 0816 REV C RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPL Y SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 0.70 ±0.05 0.25 ±0.05 4.10 ±0.05 5.50 ±0.05 2.65 ±0.05 3.10 ±0.05 4.50 ±0.05 PACKAGE OUTLINE 2.65 ±0.10 3.65 ±0.10 3.65 ±0.05 28-Lead Plastic QFN (4mm × 5mm) (Reference LTC DWG # 05-08-1712 Rev C)
Rev. AFor more information www.analog.com Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
REVISION HISTORY
REV DATE DESCRIPTION PAGE NUMBER A 02/21 Updated LED current regulation to 2.5% accuracy Added AEC-Q100 Qualification and automotive model order information Changed BST pin capacitor to 33 nF Clarified Absolute Maximum Ratings Clarified V REF Voltage conditions Revised Electrical Characteristic values 1, 2 1, 10, 12, 21-29, 30, 32 3, 4
Rev. A For more information www.analog.com ANALOG DEVICES, INC. 2018–2021 www.analog.com RELATED PARTS TYPICAL APPLICATION PART NUMBER DESCRIPTION COMMENTS LT3922 36V, 2A Synchronous Step-Up LED Driver VIN = 2.8V to 36V, VOUT(MAX) = 40V, 128:1 Internal Dimming and 5,000:1 External Dimming, ISD = 1µA, 4mm × 5mm QFN-28 LT3932/LT3932-1 36V, 2A Synchronous Step-Down LED Driver V IN = 3.6V to 36V, VOUT = 0V to 36V, 128:1 Internal Dimming and 5,000:1/10,000+:1 External Dimming, ISD = 1µA, 4mm × 5mm QFN-28 LT3952 60V, 4A LED Driver with 4000:1 PWM Dimming with Spread Spectrum VIN: 3V to 42V, V OUT(MAX) = 60V, 4000:1 PWM , 20:1 Analog, I SD < 1µA, LT 3518 2.3A, 2.5MHz High Current LED Driver with 3000:1 Dimming with PMOS Disconnect FET Driver V IN: 3 V to 30V, V OUT(MAX) = 45V, 3000:1 PWM Dimming, I SD < 1μA, 4mm × 4mm QFN-16 and TSSOP-16E Packages LT 3755/LT3755-1/ LT3755-2 40VIN, 75V OUT, 1MHz Non-Synchronous Boost LED Controller VIN: 4.5V to 40V, V OUT: V IN to 75V, ±4% Current Accuracy, 3mm × 3mm QFN-16 and MSE-16 LT 3761 60VIN, 80V OUT, 1MHz Non-Synchronous Boost LED Controller with Internal PWM Generator VIN: 4.5V to 60V, VOUT: VIN to 80V, ±3% Current Accuracy, External and Internal PWM Dimming, MSE-16 LT3763 60V, 1MHz Synchronous Buck LED Controller V IN: 6V to 60V, VOUT: 0V to VIN –2V, ±6% Current Accuracy, TSSOP-28 LT3795 110V, 1MHz Non-Synchronous Boost LED Controller with Spread Spectrum Frequency Modulation V IN: 4.5V to 110V, V OUT: V IN to 110V, ±3% Current Accuracy, Internal Spread Spectrum, TSSOP-28 LT 8391 60V, 650kHz Synchronous 4-Switch Buck-Boost LED Controller with Spread Spectrum V IN: 4V to 60V, VOUT: 0V to 60V, ±3% Current Accuracy, External and Internal PWM Dimming, Spread Spectrum, TSSOP-28 and 4mm × 5mm QFN-28 Low EMI 2MHz, 333mA Boost LED Driver with SSFM Peak Radiated EMI Performance (CISPR25) Average Radiated EMI Performance (CISPR25) VIN VIN 8V TO 27V 4.7µF 365k 59.0k EN/UVLO OVLO INTVCC FAUL T BST SW VOUT VOUT FB RP V CRT ISP GND GND ISN PWMTG ISMON
39221 TA11a
33.2k 24k 0.1µF 0402 33µF 0.22nF 0402 0.1µF 33nF 4.7µH M1 D1 300m/uni03A9 2.2µF 0.47µF 0.47µF FB2 OUTPUT EMI FIL TER FB1 INPUT EMI FIL TER 30V 333mA LED SS 45.3k 2MHz 332k 122Hz 100nF 2.2µF L1: WURTH 74437324047 M1: VISHAY Si2319CDS FB1: WURTH 7427920415 FB2: WURTH 742792097 D1: NXP PMEG4010 CEJ SYNC/SPRD VREF PWMPWM DIM ANALOG DIM CTRL 100k1µF 100k 2.2µF CLASS 5 PEAK LIMIT L T3922-1 2MHz f SW PEAK EMI FREQUENCY (MHz) 100 200 300 400 500 600 700 800 900 1000 –15 –10 AMPLITUDE (dBµV/m)
39221 TA11b
FREQUENCY (MHz) 100 200 300 400 500 600 700 800 900 1000 –15 –10 AMPLITUDE (dBµV/m)