SC5014A High Efficiency 2-Channel HB LED Driver with I2C Interface and Direct PWM Dimming POWER MANAGEMENT Features Description Input Voltage — 4.5V to 27V Output Voltage — Up to 50V Step-up (Boost) Controller Ultra-Fast Transient Response (<100μs) Programmable Switching Frequency Linear Current Sinks 2 Strings, up to 240mA/String Current Matching ±1% Current Accuracy ±2% PWM Dimming Direct PWM Dimming, 1000:1 at 1KHz Input Dimming Frequency 100Hz-30kHz 5-Bits Analog Dimming I2C Interface Fault Status — Open/Short LED, UVLO, OTP Protection Features Open/Shorted LED(s) and adjustable OVP Over-Temperature and UVLO Shutdown Protection 4mm X 4mm 20-pin QFN Package The SC5014A is a 2-channel, highly integrated, high-efficiency step-up (boost) HB LED driver designed to reduce the thickness of mid-size LCD displays. It features a wide input voltage range (4.5V to 27V), direct PWM dimming, analog dimming, a flexible output configuration, an I2C interface, and numerous protection features. The SC5014A exhibits 2% to 4% higher efficiency when using the same size inductors as existing LED drivers. But, unlike existing devices, it can also operate with inductors that are up to 10x smaller without sacrificing efficiency. This part can also use very low-profile inductors (as small as 2.2µH, 1mm height), which allows LED drivers to be built directly into the LCD panel to enable ultra-thin displays. The boost controller, with programmable switching frequency from 200kHz to 2.2MHz, maximizes efficiency by dynamically minimizing the output voltage while maintaining LED string current accuracy. It provides excellent line and load response with no external compensation components. An external resistor adjusts the current from 40-240mA per string. Applications UltrabooksTM, All-in-One PCs, Monitors, AutomotiveDisplay Backlighting Backlighting for Mid-Size Displays Typical Application Circuit V IN = 4 .5 to 2 7 V L1 NDRV R1 R2 V C C = 4 .5 to 5 .5 V R3 EN FLT SDA SCL PW MI PW MI C3 R6 Q1 C5 R4 U VLO EN F o r I2 C V O U T u p to 5 0 V CS R8 OVP VCC FLT D1 R9 S C 5014A IO 1 IO 1 REF IO 2 SCP IO 2 U p to 2 4 0 m A /S trin g R5 R10 R 11 FSET IS E T E -P A D PGND Revision 2.0 SC5014A VCC NDRV PGND CS Ordering Information EN Pin Configuration 20 19 18 17 16 U VLO 1 15 OVP SCP 2 14 IO 1 REF 3 13 IO 1 FSET 4 12 IO 2 NC 5 11 IO 2 9 10 PW MI SDA 8 FLT 7 IS E T 6 SCL AGND Device Package SC5014AMLTRT(1)(2) MLPQ-20 4×4 SC5014AEVB Evaluation Board Notes: (1) Available in tape and reel only. A reel contains 3,000 devices. (2) Lead-free packaging only. Device is WEEE and RoHS compliant, and halogen free. Marking Information 5 0 1 4A yyw w xxxxx xxxxx nnnn = Part Number yyww = Date code xxxxx = Semtech Lot No. xxxxx = Semtech Lot No. SC5014A Absolute Maximum Ratings (refer to PGND) Recommended Operating Conditions VCC Pin (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 Ambient Temperature Range (°C). . . . . . . . . -40 < TA < +85 IO Pins (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +30 VIN (V). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 to 27 DRVN, OVP, CS, EN, UVLO, SCP, REF, FLT (V) . . -0.3 to +6.0 IO Current per String (mA) . . . . . . . . . . . . . . . . . . 250 (max) FSET, SCL, SDA, ISET, PWMI (V) . . . . . . . . . . . . . -0.3 to +6.0 Thermal Information PGND to AGND (V). . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +0.3 ESD Protection Level(1) (kV) ������������������������������������������������������� 2 Thermal Resistance, Junction to Ambient(2) (°C/W) . . . . 32 Maximum Junction Temperature (°C). . . . . . . . . . . . . . . +150 Storage Temperature Range (°C) . . . . . . . . . . . . -65 to +150 Peak IR Reflow Temperature (10s to 30s) (°C) . . . . . . . +260 Exceeding the above specifications may result in permanent damage to the device or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not recommended. NOTES: (1) Tested according to JEDEC standard JESD22-A114-B. (2) Calculated from package in still air, mounted to 3 x 4.5in, 4-layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards. Electrical Characteristics Unless noted otherwise, TA = 25°C for typical, -40°C < TA = TJ < 85°C for min and max. VCC = 5V, RISET = 25.5KΩ, RFSET = 100KΩ. Parameter Symbol Conditions Min Typ Max Units 5.5 V 4.4 V Input Supply VCC Supply Voltage VCC 4.5 VCC Under-Voltage Lockout Threshold VCC-UVLO(TH) VCC Voltage Rising 4.2 VCC Under-Voltage Lockout Hysteresis VCC-UVLO(HYS) VCC Voltage Falling 180 mV VCC Quiescent Supply Current ICC(Q) EN = 5V, Switching, No Load 2 mA VCC Supply Current in Shutdown ICC(SD) EN = 0V VUVLO Under-Voltage Lockout Threshold VUVLO(TH) UVLO Pin Voltage Rising 1.18 IUVLO Under-Voltage Lockout Hysteresis IUVLO(HYS) UVLO Pin Voltage Falling VREF Bandgap Voltage VREF 1 µA 1.23 1.28 V 7 10 13 µA 1.20 1.23 1.26 V External FET Gate Drive DRVN High Level VDRVN(H) 100mA from DRVN to GND VCC -0.5 VCC -0.2 V DRVN Low Level VDRVN(L) -100mA from DRVN to VCC 0.2 0.5 V DRVN On-Resistance RDRVN DRVN High or Low 2 5 Ω DRVN Sink / Source Current IDRVN DRVN Forced to 2.5V 1 A Boost Converter CS Current Limit Threshold Soft-Start Time (1) VCS(ILIM) tSS 0.36 From EN to End of Soft-Start 0.40 4.4 0.44 V ms SC5014A Electrical Characteristics (continued) Parameter Symbol Conditions Min Typ Max Units Boost Oscillator Frequency FSW RFSET = 100kΩ 0.85 1 1.15 MHz Boost Oscillator Frequency FOSC RFSET Varies 0.2 2.2 MHz Maximum Duty Cycle DMAX 88 92 % Control Signals: EN, PWMI, SDA, SCL High Voltage Threshold VIH VCC = 4.5V to 5.5V Low Voltage Threshold VIL VCC = 4.5V to 5.5V 0.8 V VSDA(L) -6mA from VCC to SDA 0.3 V ILEAK VEN = 0V, VPWMI = VISET = VFSET = VSDA = VSCL = 5.0V -1 1 µA 100 30k Hz 1.3 V SDA Output Low Pin Leakage Current 2.1 V PWM Dimming Input PWMI Input Dimming Frequency FPWMI Over-Voltage Protection OVP Trip Threshold Voltage VOVP(TRIG) OVP Rising 1.1 1.2 OVP Hysteresis VOVP(HYS) OVP Falling 10 OVP Leakage Current IOVP(LEAK) OVP = 5V 0.1 TPWM(MIN) FPWM(LED) = 100Hz - 30kHz 300 ns 1.23 V 0.9 V mV 1 µA Current Sink (IO ) IOx Dimming Minimum Pulse Width ISET pin Voltage VISET Regulation Voltage VIOn(REG) Voltage of Regulating String Current Sink Disable Threshold VIOn(DIS) Checked at Power-up Current Sink Rise/Fall Time (1) tRISE/FALL Rising Edge from 10% to 90% of IO(n) LED Current Accuracy IOn(ACC%) PWMI = 100%, TA=+25 °C LED Current Matching (2) IOn(MATCH) IOn Off Leakage Current IOn(LEAK) 0.6 V 25 204 mA PWMI = 100%, TA=+25 °C ±1.0 % PWMI = 100%, TA=-40 °C, +85 °C ±2.0 % 1 µA PWMI = 0V, EN = 0V, VIO1 = 25V 196 200 ns 0.1 SC5014A Electrical Characteristics (continued) Parameter Symbol Conditions LED Short-Circuit Protection Threshold VIOn(SCP) R4 and R5 (3) LED Open-Circuit Protection Threshold VIO_OCP Min Typ Max Units 23xVSCP V Fault Protection LED Short-Circuit Fault Delay tSCP(DELAY) VOVP Set to 1.5V, FLT Goes Low FLT Pin Leakage Current IFLT(LEAK) VEN = 0V, VFLT = 5.0V FLT Output Low VFLT(LOW) -5mA from FLT to VCC 17xVSCP 20xVSCP 0.2 V 1 µs -1 1 µA 0.3 V Over-Temperature Protection Thermal Shutdown Temperature TOTP 150 °C Thermal Shutdown Hysteresis TOTP-H 10 °C I2C Control Interface: SDA, SCL Timing Specifications SCL Clock Frequency FSCL SCL Clock Low Period tLOW(SCL) 1.3 µs SCL Clock High Period tHIGH(SCL) 0.6 µs Hold Time Start Condition tHD(START) 0.6 µs SDA Setup Time tSU(SDA) 100 ns SDA Hold Time tHD(SDA) 0 Setup Time Stop Condition tSU(STOP) 0.6 µs tBF 1.3 µs Bus Free Time Between Stop & Start 400 0.9 kHz µs Notes: (1) Ensured by design and characterization, not production tested. (2) LED current matching for 2 channels is defined as the largest of the two numbers, i.e., (MAX-AVG)/AVG and (AVG-MIN)/AVG; where MAX is the maximum LED channel current, MIN is the minimum LED channel current and AVG is the average of the 2 LED channel currents. (3) Refer to the application circuit on page 20, Figure 2. SC5014A BacklightEfficiencyvs.InputVoltage BacklightEfficiencyvs.InputVoltage Typical Characteristics ˕˴˶˾˿˼˺˻̇ʳ˘˹˹˼˶˼˸́˶̌ʳ̉̆ˁʳ˜́̃̈̇ʳ˩̂˿̇˴˺˸ Backlight Efficiency vs. Input Voltage Backlight˕˴˶˾˿˼˺˻̇ʳ˘˹˹˼˶˼˸́˶̌ʳ̉̆ˁʳ˜́̃̈̇ʳ˩̂˿̇˴˺˸ Efficiency vs. Input Voltage 10S2P ˄˃˃ 240mA/CH 120mA/CH ˄˅˃̀˔ ˌ˃ ˅ˇ˃̀˔ ˘˹˹˼˶˼˸́˶̌ʻʸʼ Efficiency(%) 7S4P ˌˈ Efficiency(%) ˌˈ ˘˹˹˼˶˼˸́˶̌ʻʸʼ 240mA/CH ˄˃˃ 10S4P ˊ˦ ˌ˃ ˄˃ ˋˈ ˋˈ BacklightEfficiencyvs.LEDstringCurrent BacklightEfficiencyvs.LEDstringCurrent ˋ˃ ˋ˃ ˃ ˈ ˄˃ ˄ˈ ˅˃ (V) ˩V˜ˡINʻ˩ʼ ˅ˈ ˆ˃ ˃ ˌˈ 120mA/CH ˘˹˹˼˶˼˸́˶̌ʻʸʼ 240mA/CH ˉ˃̀˔ ˋ˃ ˄˅˃̀˔ ˊˈ PWMDimmingLinearity(100Hz) ˉˈ ˃ 240mA/CH 120mA/CH ˋˈ ˉ˃̀˔ ˋ˃ ˄˅˃̀ ˊˈ ˅˃ ˇ˃ ˉ˃ ˉˈ ˋ˃ LED PWM Dimming Duty Cycle (%) ˅˃PWMDimmingLinearity(30KHz) ˇ˃ ˉ˃ ˋ˃ ˃ ˄˃˃ ˄˃˃ LED PWM Dimming Duty Cycle (%) ˟˘˗ʳˣ˪ˠʳ˗˼̀̀˼́˺ʳ˗̈̇̌ʳ˖̌˶˿˸ʳʻʸʼ ˟˘˗ʳˣ˪ˠʳ˗˼̀̀˼́˺ʳ˗̈̇̌ʳ˖̌˶˿˸ʳʻʸʼ PWM Dimming Linearity 240mA/CH, 10S2P, 100Hz Dimming 240mA/CH, 10S2P, 30KHz Dimming ˅ˇ˃ CH1 CH2 CH1 CH2 ˄ˋ˃ ˜ˢʻ̀˔ʼ ˖˛˄ ˖˛˅ ˄˅˃ ˉ˃ Iout (mA) ˄ˋ˃ Iout (mA) ˆ˃ ˕˴˶˾˿˼˺˻̇ʳ˘˹˹˼˶˼˸́˶̌ʳ̉̆ˁʳ˜́̃̈̇ʳ˩̂˿̇˴˺˸ʳʻ˄˅˩˼́ʼ PWM Dimming Linearity ˜ˢʻ̀˔ʼ ˅ˈ ˊ˃ ˊ˃ ˅ˇ˃ ˅˃ ˌ˃ Efficiency(%) ˘˹˹˼˶˼˸́˶̌ʻʸʼ Efficiency(%) VIN=12V ˌˈ ˋˈ ˄ˈ VIN(V) Backlight Efficiency vs. LED String Current ˕˴˶˾˿˼˺˻̇ʳ˘˹˹˼˶˼˸́˶̌ʳ̉̆ˁʳ˜́̃̈̇ʳ˩̂˿̇˴˺˸ʳʻˉ˩˼́ʼ ˌ˃ ˄˃ ˩˼́ʻ˩ʼ Backlight Efficiency vs. LED String Current VIN=6V ˈ ˖˛˄ ˖˛˅ ˄˅˃ ˉ˃ ˃ ˃ ˅˃ ˇ˃ ˉ˃ ˋ˃ LED PWM Dimming Duty Cycle (%) ˄˃˃ ˃ ˃ ˅˃ ˇ˃ ˉ˃ ˋ˃ LED PWM Dimming Duty Cycle (%) ˗̈̇̌ʻʸʼ ˄˃˃ ˗̈̇̌ʻʸʼ SC5014A LEDStringCurrentvs.RISET LEDStringCurrentMatchingvs.Temperature Typical Characteristics (continued) LED String Current vs. R ˦̊˼̇˶˻˼́˺ʳ˙̅˸̄̈˸́˶̌ʳ̉̆ˁʳ˥ ˜˦˘˧ ISET LED String Current Matching vs. Temperature VCC=5V, 240mA/CH ˆ˃˃ ˜̂̈̇ʻ̀˔ʼ LED String Current (mA) LED ˟˘˗ʳ˦̇̅˼́˺ʳ˖̈̅̅˸́̇ʳˠ˴̇˶˻˼́˺ʻʸʼ String Current Matching (%) ˄ˁˉ ˄ˁ˅ ˃ˁˋ ˃ˁˇ ˅ˈ˃ ˅˃˃ ˄ˈ˃ ˄˃˃ ˃ˁ˃ ˀˇ˃ SwitchingFrequencyvs.RFSET ˀ˅˃ ˃ ˅˃ ˇ˃ Temperature (°C) ˉ˃ ˃ ˋ˃ ˃ ˄˃˃ ˧˸̀̃˸̅˴̇̈̅˸ʻкʼ ˅ˇ˃˃ LED String Current Accuracy (mA) ˟˘˗ʳ˦̇̅˼́˺ʳ˖̈̅̅˸́̇ʳ˔˶˶̈̅˴˶̌ʳʻ˩ʼ ˅˃˃˃ ˄ˉ˃˃ ˄˅˃˃ ˋ˃˃ ˇ˃˃ ˃ ˋ˃ RISET(KΩ) ˄˃˃ ˄˅˃ ˄ˇ˃ ˆ˃˃ ˇˈ˃ RFSET(KΩ) AnalogDimming ˥˙˦˘˧ʻ˞Өʼ ˥˙˦˘˧ʻ˞Өʼ ˜ˢˆʾˇ ˅ˇˉ ˅ˇˇ ˅ˇ˅ ˅ˇ˃ ˅ˆˋ ˅ˆˉ ˅ˆˇ ˉ˃˃ ˀˇ˃ ˀ˅˃ ˃ ˅˃ ˇ˃ Temperature (°C) ˉ˃ ˋ˃ ˄˃˃ ˧˸̀̃˸̅˴̇̈̅˸ʳʻкʼ PWM PWM Dimming Direct (100Hz,Linearity 30KHz) LED String Current vs. Analog Dimming Control Register (IDAC) Value 240mA/CH, 10S2P 250 100Hz 30KHz 100.00 150 IO3+4 100 100Hz 10.00 30KHz 1.00 0.10 50 0 Output Current (mA) 200 IO(mA) ILED(mA) LED String Current (mA) ˉ˃ VCC=5V, 240mA/CH ˅ˇˋ ˄ˈ˃ ˇ˃ LED String Current Accuracy vs Temperature ˦̊˼̇˶˻˼́˺ʳ˙̅˸̄̈˸́˶̌ʳ̉̆ˁʳ˥˙˦˘˧ ˃ ˅˃ ˥˜˦˘˧ʻ˞Өʼ Switching Frequency vs. RFSET Boost Switching Frequency (KHz) ˙˦ʻ˞˛̍ʼ CurrentAccuracyvs.Temperature ˈ˃ 0 4 8 12 16 20 24 28 IDAC Register Value (in decimal format) DEC 32 0.01 0.01 0.10 1.00 10.00 100.00 LED PWM Dimming Duty Cycle(%) Duty(%) SC5014A Start-upintoLEDsOpen-circuitProtection Testing condition: VIN=12V,VCC=5V, LEDs=10S4P@100mA, 1MHz, UnusedString Testing condition: VIN=12V,VCC=5V, LEDs=10S4P@100mA, 1MHz, 25к к ,IO1&IO2 short to GND 25к к ,IO1&IO2 open Typical Characteristics (continued) LED Open Circuit Protection Unused String Starting with one unused LED string Starting with one LED string open-circuit VIN VIN 8V/div. VIN VIN 8V/div. VOUT VOUT IOUT 10V/div. IOUT Start-upintoShortcircuitProtection 200mA/div. /FLT /FLT 5V/div. Testing condition: VIN=12V,VCC=5V, LEDs=10S4P@100mA, 1MHz, 25к к, Time (5ms/div) two LEDs short circuit VOUT VOUT 10V/div. IOUT 100mA/div. /FLT 5V/div. IOUT VINStartUP /FLT Testing condition: VIN=12V,VCC=5V, LEDs=10S4P@100mA, 1MHz, 25к к LED Short Circuit Protection Time (5ms/div) Start Up by Vin Two LEDs short Circuit in one string 10S2P, 240mA/CH VIN VIN VIN 8V/div. VOUT VOUT VOUT 10V/div. IOUT 200mA/div. /FLT 5V/div. IOUT LoadTransientResponse /FLT Testing condition: VIN=12V, 25к к, LEDs=10S4P@100mA/CH, 1MHz, Time (5ms/div) PWMI=10KHz, Duty=0.5% to 99% VIN 5V/div. VOUT 10V/div. IOUT 200mA/div. VIO1 5V/div. LoadTransientResponse V_IO1 Testing condition: VIN=12V, 25к к, LEDs=10S4P@100mA/CH, 1MHz, Time (5ms/div) PWMI=10KHz, Duty=99% to 0.3% Load Transient Response Load Transient Response PWM(10KHz)=0.5% to 99%, VIN=12V, 200mA/CH X 2 VOUT 5V/div. IOUT VOUT VIO1 5V/div. VOUT 1V/div. PWM(10KHz)=99% to 0.3%, VIN=12V, 200mA/CH X 2 VOUT VIO1 5V/div. V_IO1 V_IO1 IOUT 200mA/div. IOUT IOUT IOUT 200mA/div. PWMI 6V/div. SDA Time (100us/div) PWMI 6V/div. SDA Time (100ms/div) LEDDimming LEDDimming SC5014A Testing condition: VIN=12V, 25к к, LEDs=10S4P@100mA/CH, 1MHz, PWMI=100Hz, Duty=0.04% Testing condition: VIN=12V, 25к к, LEDs=10S4P@100mA/CH, 1MHz, PWMI=30KHz, Duty=4% Typical Characteristics (continued) PWM Dimming PWM Dimming 0.04% dimming@100Hz, VIN=12V, 10S2P, 200mA/CH VOUT 1V/div. VIO1 5V/div. VOUT V_IO1 IOUT AnalogDimmingTransientviaI2C 200mA/div. IOUT PWM 6V/div. /FLT Testing condition: VIN=12V, 25к кTime , LEDs=10S4P@100mA, 1MHz, 0% to (5ms/div) 100% VOUT 1V/div. VIO1 3V/div. VOUT V_IO1 IOUT AnalogDimmingTransientviaI2C 200mA/div. IOUT PWM 6V/div. /FLT Testing condition: VIN=12V, 25к к, LEDs=10S4P@100mA/CH, 1MHz, Time (10us/div) 100% to 9.68% Analog Dimming Transient via I2C Analog Dimming Transient via I2C 0% to 100% dimming, 200mA/CH 100% to 9.68% dimming, 200mA/CH VOUT VOUT 10V/div. VIO1 1V/div. 4% dimming@30KHz, VIN=12V, 10S2P, 200mA/CH VOUT 10V/div. VOUT VIO1 1V/div. V_IO1 V_IO1 IOUT 200mA/div. IOUT IOUT 200mA/div. SDA 6V/div. IOUT LineTransientResponse LineTransientResponse SDA SDA 6V/div. Testing condition: Vin fluctuation (7V to 18V), PWM dimming Freq.=200Hz, Time (100us/div) 㷄; PWM dimming duty=0.5%; VIN rising time 㻃10us, 25㷄 Time (100us/div) Testing condition: Vin fluctuation (7V to 18V), PWM dimming Freq.=200Hz, PWM dimming duty=100%; VIN rising time ≈10us, 25к к; Line Transient Response VIN 5V/div. SDA Line Transient Response 7VIN to 18VIN, 200Hz and 100% dimming duty, 200mA/CH 7VIN to 18VIN, 200Hz and 0.5% dimming duty, 200mA/CH VIN VIN VIN 5V/div. VOUT 1V/div. VOUT 1V/div. VIO1 1V/div. IOUT 200mA/div. Vout VIO1 1V/div. Vout V_IO1 V_IO1 IOUT Time (500us/div) PWM 5V/div. PWMI Time (20ms/div) SC5014A Pin Descriptions Pin # Pin Name 1 UVLO Pin Function Input under-voltage lockout pin — Device is disabled when this pin is less than 1.23V (nominal). Add a resistor divider from this pin to the input voltage and AGND, respectively. 2 SCP Short-circuit LED protection programming pin — Shorted LED protection disables the individual channel when the current sink voltage exceeds the programmed voltage threshold. Adding a resistor divider from this pin to REF and PGND programs the shorted-LED protection up to 20x the VSCP voltage. Pulling the pin high to VCC disables the SCP feature on all channels. 3 REF 1.23V reference voltage output pin — Connect a 1µF ceramic bypass capacitor from this pin to ground. 4 FSET Step-up (boost) frequency set pin — Connect a resistor from this pin to ground to set the frequency from 200kHz to 2.2MHz. 5 NC No connect. This can be left floating or connected to GND. 6 SCL I2C serial clock input — This pin must be connected to ground if not used. 7 SDA I2C serial data input — This pin must be connected to ground if not used. 8 ISET LED current programming pin — Connect an external resistor to ground to program the current in the LED strings. For more details please refer to LED String Peak Current Programming on page 13. 9 FLT Logic low fault status pin — Open-drain output is latched low when fault condition is detected: Open/Short LED, Shorted String, OVP or OTP. Fault status can be reset by removing fault condition(s) and toggling the EN, VCC or UVLO pins. This pin can be left floating if not used. 10 PWMI 11 ~14 IO2 ~ IO1 Regulated current sink LED channel 2 to channel 1 respectively . Connect the related IO pin to the cathode of the bottom LED in string 2 to string 1 respectively. Connect the related IO pin to ground to disable the related LED string during power on. 15 OVP Over-voltage feedback pin — Over-voltage activated when pin voltage exceeds 1.2V. Use a resistor divider tied to the output and GND to set the OVP level. 16 CS 17 PGND Power ground — Tie this pin to the power ground plane close to input and output decoupling capacitors. 18 NDRV Gate drive for the external step-up (boost) N-Channel MOSFET. 19 VCC Input bias voltage supply for the IC — Accepts 4.5-5.5V inputs. Add a 1µF or larger ceramic bypass capacitor from this pin to ground. 20 EN Logic high enable pin — Pull logic high to enable the device or pull low to disable and maintain low shutdown current. - PAD AGND thermal pad for heatsinking purposes — It should be connected to ground plane for proper circuit operation. LED string PWM dimming control input. Step-up (boost) switch current sense pin — Connect a resistor from this pin to ground for current sense - utilized in peak current mode control loop and over-current sense circuitry. 10 SC5014A Block Diagram REF FS E T SCP VBG U V LO EN X 20 OVP - NC OVP + S C _R E F BG B oost O scillator OSC LS C ontrol Logic NDRV O TP VCC C LIM PW M COMP + ILIM DC - + - + S lope C om p CS COMP EA PW MI + DC - M inim um V oltage D etection 4 4 O C /S C D etection I2C Interface SCL FLT IO 2 4 2 I C Interface and LE D C ontrol Logic IS E T A djust S C _R E F IO 1 LE D O pen/S hort Fault SDA IO 1 5 5-bit DAC IO 2 I-R E F ADJ O TP IS E T PGND 11 SC5014A Applications Information General Description The SC5014A contains a high frequency, current-mode, internally compensated boost controller with 2 constant current sinks for driving LED strings. The LED current for both strings is programmed by an external resistor. The boost converter operates to maintain minimal required output voltage for regulating the LED current to the programmed value. A typical backlight application uses 3 to 14 LEDs per each string, with current driven up to 240mA. The unique control loop of the SC5014A allows fast transient response in dealing with line and load disturbances. The SC5014A, operating with an external power MOSFET, regulates the boost converter output voltage based on the instantaneous requirement of the 2 string current sources. This provides power to the entire lighting subsystem with increased efficiency and reduced component count. It supports PWM dimming frequencies from 100Hz to 30kHz and the supply current is reduced to 2mA typical when both LED strings are off. Start-Up When the EN pin is pulled up high (>2.1V), the device is enabled and the UVLO and VCC pin voltages are checked. The VCC voltage has fixed under-voltage rising and falling trip points. If the VCC pin is higher than 4.2V and the UVLO pin voltage is greater than 1.23V, the SC5014A goes into a start-up sequence. The UVLO pin voltage can be used to program the input power source voltage VIN turn-on threshold and its hysteresis (refer to the detailed application circuit on page 20, Figure 2) as shown by the following equations: VIN_TurnOn [V] = 1.23 X (R1 + R2) / R1 VIN_Hysteresis [V] = 10-5 X R2 [Ω] In the next phase, the SC5014A checks each IO pin to determine if the respective LED string is enabled. Each IO pin is pulled up with a 100µA current source. If any IO pin is connected to ground, it will be detected as an unused string, and will be turned off. This unused string checking procedure typically takes 1ms. After this, the SC5014A enters into a soft-start sequence. The soft-start function helps to prevent excess inrush current through the input rail during start-up. In the SC5014A, the soft-start is implemented by slowly ramping up the reference voltage fed to the error amplifier. This closed loop start-up method allows the output voltage to ramp up without any overshoot. The duration of the soft-start in the SC5014A is controlled by an internal timing circuit, which is used during start-up and is based on the boost converter switching frequency. For example, with switching frequency at 1MHz, it is 8ms typical and becomes 4ms typical when the switching frequency is 2MHz. If the PWM voltage goes low while the SC5014A is in softstart operation, the SC5014A switches to standby mode, where the external power MOSFET and the LED current sources will be turned off immediately. The internal softstart timer is turned off and the soft-start value is saved. When the PWM voltage goes high again, the soft-start resumes from the previously saved value. Each LED current source tries to regulate the LED current to its set point. The control loop will regulate the output voltage such that all the IO pin voltages are at least 0.9V typical. Shutdown When the EN pin is pulled down below 0.8V, the device enters into shutdown mode. In this mode, all the internal circuitry is turned off and the supply current is less than 1µA (max). In the scenario where the EN pin voltage is high, but VCC voltage falls below the respective UVLO threshold, the SC5014A goes into a suspend mode. In this mode, all the internal circuitry except the reference and the oscillator are turned off. Thermal Shutdown (TSD) If the thermal shutdown temperature of typical 150°C is reached, the boost converter and all IO current sources are turned off. The FLT pin is forced low in this condition. When the temperature falls below the TSD trip point by 10°C, the SC5014A will restart following the start-up sequence as described before. The FLT pin is latched and will stay low, it is reset by cycling the EN, VCC or UVLO. 12 SC5014A Applications Information (continued) Boost Converter Operation The SC5014A includes a boost controller with programmable switching frequency. It applies a current-mode control method with an integrated compensation loop as shown in the diagram below. The clock (see block diagram on page11) from the oscillator sets the latch and turns on the external power MOSFET, which serves as the main power switch. The current flowing through this switch is sensed by the current sense resistor in series with the switch. The sensed switch current is summed with the slope-compensated ramp and fed into the modulating input of the PWM comparator. When the modulating ramp intersects the error amplifier output (COMP), the latch is reset and the power MOSFET is turned off. The sense resistor also sets the peak current limit of the power MOSFET, IOCP using the following equation: IOCP[A] = 0.4 / RCS [Ω] V IN = 4 .5 V to 2 7V OSC C o n tro l L o g ic LS + NDRV Q1 CS The SC5014A provides 2 current sinks and each can sink up to 240mA current. It incorporates LED string shortcircuit protection (trip-level programmable; can be disabled) and LED string open-circuit protection. C5 - + COMP + DC - IO M in . V o lta g e D e te ctio n The current-mode control system contains two loops. For the inner current loop, the error amplifier (EA) output (COMP) controls the peak inductor current. In the outer loop, the EA regulates the output voltage for driving the LED strings. Boost Converter Switching Frequency Selection The resistor between FSET and GND sets the boost converter switching frequency (200kHz to 2.2MHz) using the following equation: When the OVP pin voltage exceeds 1.2V, the boost converter turns off and the FLT pin is pulled low. When the OVP pin voltage falls below the OVP threshold (falling), the boost converter restarts and the FLT pin is released. There is 10mV hysteresis between the OVP pin threshold (falling) and the OVP pin threshold (rising). This results in an output voltage hysteresis expressed as: LED Current Sink R4 EA OVP Trip Voltage [V] = 1.2 X (R11 + R12) / R12 Output OVP Hysteresis [mV] = 10 X (R11 + R12) / R12 PW M COMP S lo p e C om p L1 D1 B o o st O scilla to r Over-Voltage Protection (OVP) The SC5014A features programmable output over-voltage protection to prevent damage to the IC and output capacitor in the event of a LED string open-circuit. The boost converter output voltage is sensed at the OVP pin through the resistor voltage divider. The OVP trip threshold (refer to detailed application circuit on page 20, Figure 2) can be calculated using the following equation: fSW [kHz] = 105/ RFSET [kΩ] A higher switching frequency allows the use of low-profile height inductors for space-constrained and cost-sensitive applications. LED String Peak Current Programming LED string peak current (at 100% dimming) can be set by selecting resistor RISET, connected between ISET and GND. The relationship between RISET resistance and single LED string peak current is calculated using the following equation: ILED [mA] = 2 X (1036 X 1.23) / RISET [kΩ] The string current can be programmed up to 240mA. LED Connection Two strings of LEDs can be connected to pin IO1 and pin IO2. Pins IO1,2 showed stay connected. Unused Strings The SC5014A may be operated with less than 2 strings. In this mode of operation, the unused IO pin should be connected to ground. During start-up, these unused strings are detected and disabled while other active strings work normally, and FLT does not get pulled low. 13 SC5014A Applications Information (continued) LED Short-Circuit Protection (SCP) The SC5014A features a programmable LED short-circuit protection (SCP). This allows the part to be customized based on the LED forward voltage (VF) mismatches between the LED strings. If one or more LEDs are detected as shortcircuited, the corresponding string will be latched off. The voltages on both IO pins are monitored to check if any IO pin exceeds the SCP trip point. The IO voltage for LED string(s) with faulty short-circuit LED(s) will be higher than other normal IO pin voltage. This LED short-circuit protection trip level (see detailed application circuit on page 20, Figure 2) is expressed by the following equation: current sink latch-off can be reset by cycling UVLO, VCC or EN. The analog dimming method can be used in conjunction with PWM dimming to increase the dimming resolution. The fast loop response of the SC5014A allows the LED current to transition to a new value within 160µs or so. Please refer to the graphs in the typical characteristics section. VSCP_Trip [V] = 20 X (1.23 X R4) / (R4 + R5) If any IO pin voltage exceeds the trip voltage, the IO current sink will be latched off and the FLT will go low. This latch can be reset by cycling UVLO, VCC or EN. Other LED string is unaffected and continue in normal operation. This protection will be disabled if SCP is tied to VCC. There is a typical 10μs SCP detection time in PWM dimming applications. If the PWM dimming on-time is less than the SCP detection time, the SCP cannot be enabled. In many applications, LED strings are connected to the IO pins through a mechanical connector, which cannot support an electrical connection at specific times. This connection might cause noise on the IO pins. If this noise is large enough, it may trigger a false SCP mode. Under such condition, a ceramic decoupling capacitor (100pF ~ 8.2nF) between IO pin to ground can help prevent the SC5014A from entering the protection mode by false trigger. Or, simply disable this feature by connecting SCP pin to VCC pin. LED Open-Circuit Protection If any LED string becomes open, the respective IO pin voltage will be pulled to ground. Consequently, the internal COMP node (output of error amplifier) is driven high, which causes the boost output voltage to increase. The output voltage will be eventually clamped to a voltage set by the OVP resistor divider. Under this condition, the faulty string is latched off and the FLT pin is pulled low. The boost voltage gets regulated to the voltage required to set all non-faulty IO pins above 0.9V (typ). The other string remain in normal operation. The FLT and the faulty LED LED Analog Dimming Control The LED current in SC5014A can be dimmed via the 5-bit analog dimming register (register address: 0x02). The LED current can be adjusted in 32 steps from 0mA to maximum value, which is determined by the RISET resistor. The SC5014A has a unique DAC architecture which allows it to have excellent LED current accuracy and string-tostring matching over the entire DAC range. LED PWM Dimming Control The PWM input needs to be held high for normal operation. PWM dimming can be achieved by cycling the PWM input at a given frequency where a “low” on the PWM input turns off both IO current sinks and a “high” turns on all IO current sinks. The PWM pin can be toggled by external circuitry to allow PWM dimming. In a typical application, a microcontroller sets a register or counter that varies the pulse width on a GPIO pin. The SC5014A allows dimming over a wide frequency range (100Hz-30kHz) in order to allow compatibility with a wide range of devices. This includes the newest dimming strategies that avoid the audio band by using high frequency PWM dimming. In this manner, a wide range of illumination can be generated while keeping the instantaneous LED current at its peak value for high efficiency and color temperature. The SC5014A provides a 1000:1 dimming range at 1kHz PWM frequency. The LED current sinks turn on/off very rapidly (<25ns, typical). This allows a wide dimming ratio. An additional advantage of PWM dimming is that it avoids inrush currents when filling the boost output capacitor. Simply apply the PWM signal to the device at 10% duty for a millisecond or two, and in-rush current is reduced. This dimming time will vary based on the number of LEDs and the size of the output capacitor. This can be easily determined during testing and programmed into the microcontroller firmware. 14 SC5014A Table 1 — Fault Protection Descriptions Action on Fault Type of Fault User Disable? Fault Criteria Input Under-voltage at VIN (UVLO) No Input Under-voltage at VCC (UVLO) Recovery Device FLT pin (latching / non-latching Condition(s) FLT pin VIN < (1 + R2/R1) x 1.23 (rising) No Startup Not Active VUVLO > 1.23V (rising) High No VIN < (1 + R2/R1) × 1.23V - IUVLO × R1 (falling) Shutdown Not Active VUVLO > 1.23V (rising) High No VCC < 4.2V (rising) No Startup Not Active VCC > 4.2V (rising) High No VCC < 4.0V (falling) Shutdown Not Active VCC > 4.2V (rising) High Over-voltage Protection (OVP) No VOVP > 1.23V (rising) Regulate to OVP threshold: IO(n) = “on” Low (non-latching) VOVP < 1.22V (falling) High on removal of fault condition Over-current Protection (OCP) No VCS > 0.4V Limit Q1 FET drain current < 0.4V/R9 (typ) (1) High VCS > 0.4V High VIO(n) > 20 x VSCP Device on: IO(n) = “off” Other IO(All) = “on” Low (latching) Replace Shorted LED(s) and Toggle EN, VCC or UVLO High VIO(All) > 20 x VSCP Device latch-off; IO(All) = “off” Low (latching) Replace Shorted LED(s) and Toggle EN, VCC or UVLO High VIO(n) < 0.1V and OVP event Device on: IO(n) = “off” Other IO(All) = “on” Low (latching) Replace Open LED(s) and Toggle EN, VCC or UVLO High VIO(All) < 0.1V and OVP event Device latch-off; IO(All) = “off” Low (latching) Replace Open LED(s) and Toggle EN, VCC or UVLO High VIO(All) < 0.1V (start up) Device on: IO(n) = “off” Other IO(All) = “on” High Satisfy THYS > 10ºC; Device On; IO(All) = “on”; Toggle EN, VCC or UVLO High Shorted LED(s) Open LED(s) Unused Strings Over-Temperature Protection (OTP) Yes, tie SCP to VCC No No No TJ > 150ºC (typ) Device off; IO(All) = “off” Low (latching) Note: Refer to the application circuit example for R1 and R2 on page 20, Figure 2. 15 SC5014A Applications Information (continued) Fault Protection The SC5014A provides fault detection for low supply voltage, LED related faults, boost converter over-voltage and thermal shutdown. The open drain output pin (FLT) indicates a system fault. The nature of the fault can be read from the fault status resistor (register address: 0x00) via I2C interface. Refer to Table 1 for a description of the Fault Protection Modes. Other Possible Configurations Depending on different application requirements, the SC5014A can also be easily configured to other topologies, such as the SEPIC configuration shown in Figure 4, page 21. Li-Ion Powered Display Configuration If a Li-Ion powered display application is required, VCC is needed to power with 5V. However, VIN can be set lower from 3V to 4.2V for example. An advantage of this type of configuration is that it provides higher efficiency. Please use Figure 3 on page 20 for reference. High Output Voltage Configuration If a high output voltage application is required, an additional external cascode MOSFET can be added on each IO pin to meet such requirement, please refer to Figure 5 on page 21 for reference. In this case, the upper limit on the output voltage is mainly determined by the rating of the external MOSFET, heat dissipation, etc. PCB Layout Considerations The placements of the power components outside the SC5014A should follow the layout guidelines of a general boost converter. The Detailed Application Circuit is used as an example. . Capacitor (C2) should be placed as close as possible to the VCC and AGND to achieve the best performance. 3. The converter power train inductor (L1) is the boost converter input inductor. Use wide and short traces connecting these components. 4. The output rectifying diode (D1) uses a Schottky diode for fast reverse recovery. Transistor (Q1) is the external switch. Resistor (R9) is the switch current sensing resistor. To minimize switching noise for the boost converter, the output capacitor (C6) should be placed such that the loop formed by Q1, D1, C6 and R9, is minimized. The output of the boost converter is used to power up the LEDs. Use wide and short trace connecting Pin NDRV and the gate of Q1. The GNDs for R9 and C6 should be PGND. These components should be close to the SC5014A. 5. Resistor (R8) is the output current adjusting resistor for IO1 through IO2 and should return to AGND. Place it next to the IC. 6. Resistor (R6) is the switching frequency adjusting resistor and should return to AGND. Place it next to the IC. 7. The decoupling capacitor (C3) for Pin REF should return to AGND. Place it next to the IC. 8. Resistors (R4, R5) form a divider to set the SCP level, R4 should return to AGND. Place it next to the IC. 9. Resistors (R2, R1) form a divider to set the UVLO level for UVLO pin. R1 should return to AGND. Place it next to the IC. 0. R11 and R10 form a divider to set the OVP level for VOUT, R10 should return to AGND. Place it next to the IC. . All the traces for components with AGND connection should avoid being routed close to the noisy areas. 2. An exposed pad is located at the bottom of the SC5014A for heat dissipation and analog ground. A copper area underneath the pad is used for better heat dissipation. On the bottom layer of the PCB another copper area, connected through vias to the top layer, is used for better thermal performance. The pad at the bottom of the SC5014A should be connected to AGND. AGND should be connected to PGND at a single point for better noise immunity. 2. Capacitor (C1) is the input power filtering capacitor for the boost. It needs to be tied to PGND. 16 SC5014A Components Selection Inductor Selection The choice of the inductor affects the converter’s steady state operation, transient response, and its loop stability. Special attention needs to be paid to three specifications of the inductor, its value, its DC resistance and saturation current. The inductor’s inductance value also determines the inductor ripple current. The boost converter will operate in either CCM (Continuous Conduction Mode) or DCM (Discontinuous Conduction Mode) depending on its operating conditions. The inductor DC current or input current can be calculated using the following equation. IIN = VOUT × I OUT VIN × η IIN - Input current;IOUT – Output current; VOUT – Boost output voltage; VIN – Input voltage; η – Efficiency of the boost converter Then the duty ratio under CCM is shown by the following equation. V − VIN + VD D = OUT VOUT + VD VD – Forward conduction drop of output rectifying diode When the boost converter runs under DCM ( L < Lboundary), it has the advantages of small inductance and quick transient response; where as if the boost converter works under CCM (L > Lboundary), normally the converter has higher efficiency. When selecting an inductor, another factor to consider is the peak-to-peak inductor current ripple, which is given by the following equation: ΔIL = VIN × D fSW × L Usually this peak-to-peak inductor current ripple can be chosen between 30% to 50% of the maximum input DC current. This gives the best compromise between the inductor size and converter efficiency. The peak inductor current can be calculated using the following equation: IL-peak = IIN + VIN × D 2 × fSW × L For most applications, an inductor with a value of 2.2µH to 22µH should be acceptable, (refer to the detailed application circuit on page 20, Figure 2). The inductor peak current must be less than its saturation rating. When the inductor current is close to the saturation level, its inductance can decrease 20% to 35% from the 0A value depending on the vendor specifications. Using a small value inductor forces the converter in DCM, in which case the inductor current ramps down to zero before the end of each switching cycle. It reduces the boost converter’s maximum output current and produces a larger input voltage ripple. The DCR of the inductor plays a significant role for the total system efficiency and usually there is a trade-off between the DCR and size of the inductor. Table 2 lists some recommended inductors and their vendors. Table 2. Recommended Inductors Inductor Vendor Website HCM0703, 2.2uH~10uH www.cooperindustries.com IHLP-2525CZ-01, 4.7uH~10uH www.vishay.com MLPC0730L, 2.2uH~4.7uH www.nec-tokin.com/english Output Capacitor Selection The next design task is targeting the proper amount of output ripple voltage due to the constant-current LED loads. Usually X5R or X7R ceramic capacitor is recommended. The ceramic capacitor minimum capacitance needed for a given ripple can be estimated using the following equation: C OUT = (VOUT − VIN )× IOUT VOUT ×f SW ×VRIPPLE 17 SC5014A Application Information (continued) VRIPPLE – Peak to peak output ripple. The ripple voltage should be less than 200mV (pk-pk) to ensure good LED current sink regulation. For example, a typical application where 240mA/string current is needed, the total output current for 2 channels will be 480mA, and 6x 4.7µF capacitors are recommended. During load transient, the output capacitor supplies or absorbs additional current before the inductor current reaches its steady state value. Larger capacitance helps with the overshoot/undershoot during load transient and loop stability. diode and the inductor will be exposed to the output voltage. The external power MOSFET should be selected with its voltage rating higher than the output voltage by minimum 30%. The current rating should be enough to handle the inductor peak current. Low RDS(on) MOSFETs are preferred for achieving better efficiency. The GD (gate driver) on SC5014A provides 1A (peak) current driving capability which is suitable for most MOSFETs for high frequency operation. The average current required to drive the MOSFET is given by the following equation. IGATE = QG x fSW Input Capacitor Selection QG — Gate charge X5R or X7R ceramic capacitor is recommended for input bypass capacitor. A 1µF capacitor is sufficient for the VCC input. Bypass the VIN input with a 10µF or larger ceramic capacitor. The RDS(ON) and its RMS current IS_RMS of the power MOSFET will generate the conduction loss using the following equation. Output Freewheeling Diode Selection Schottky diodes are the ideal choice for the SC5014A due to their low forward voltage drop and fast switching speed. Table 3 shows several different Schottky diodes that work properly with the SC5014A. Verify that the diode has a voltage rating greater than the maximum possible output voltage. The diode conducts current only when the power switch is turned off. The diode must be rated to handle the average output current. A diode rated for 1A average current will be sufficient for most designs. PCOND = IS_RMS2 x RDS(on) The MOSFET’s switch loss can be calculated using the following equation. PSW = ½ x VIN x IL_PEAK x fSW x (TON + TOFF) Where TON and TOFF are the MOSFET’s on and off time and they can be estimated by the following equations. TON = t r + (5 − V Q gd plateau Table 3. Recommended Rectifier Diodes Rectifier Diode DFLS140 SS14/15/16, SS24/25/26 Vendor Website www.diodes.com www.vishay.com External Power MOSFET Selection The boost converter in SC5014A uses an external power MOSFET to regulate the output voltage and output power to drive LED loads. This boost switching structure has an advantage in that the SC5014A is not exposed to high voltage. Only the external power MOSFET, freewheeling TOFF = t f + )/ (5 + R ) g Q gd Vplateau / (5 + R g ) Where tr, tf, Qgd and Vplateau can usually be found from datasheet of the selected MOSFET. Rg is the resistance of the optional resistor connected in series on the gate of the MOSFET. 18 SC5014A Components Selection (continued) Current Sensing Resistor Selection The switch current is sensed via the current sensing resistor, RCS. The sensed voltage at this pin is used to set the peak switch current limit and also used for steady state regulation of the inductor current. The current limit comparator has a trip voltage of 0.4V (typical). R CS value is chosen to set the peak inductor and switch current using the following equation. I2SW(Peak) = 0.4/RCS For the typical application circuit shown in the detailed application circuit (page 20, Figure 2), the power dissipation on the sensing resistor is shown by the following equations. Assuming VIN = 6V and VOUT = 31.5V, thus D = 81%, PR_CS = 0.81 X (0.48/0.19)2 X 0.08 = 0.414(W) For this example, a 0.08 Ω 1% thick-film chip resistor rated at 1W can be used. The power dissipation in RCS can be calculated using the following equations. PR_CS = IRMS2 x RCS IRMS = D x [IO/(1-D)]2 IO = Output DC Current, D = Duty Cycle 19 SC5014A C1 10µF/25V x3P C S R2 787kΩ R12 20 WLEDs per channel 10kΩ 50m Ω CS R1 10kΩ R3 VCC 10kΩ R15 OVP IO1 UVLO IO1 EN FLT IO2 S C 5014A SCL SCL SDA SDA PWM PWM IO2 REF SCP PAD ISET 20kΩ FLT 2.2µF/100V x6P C S RCS C12 2.2µF C6 AON6482 NDRV GND R11 Q1 75kΩ VCC (5V) Vout up to 70V D F LS 1100 FSET PGND D1 L1 3.3µH PGND VIN (12-19V) VIN R 5, 40.2kΩ R4 10kΩ R6 R8 25.5kΩ 250kΩ C3 1µF Figure 2— Application Circuit Example, 20 LED @ 200mA C1 R2 Q1 13kΩ R3 VCC 10kΩ IO1 EN 20kΩ FLT SCL SCL SDA SDA PWM PWM SCP OVP IO1 UVLO R15 FLT 10kΩ 100m Ω R1 10kΩ CS 2.2µF/10V 249kΩ R12 5 WLEDs per stringl RCS C12 NDRV GND C6 Si2318 IO2 S C 5014A IO2 PAD REF VCC (5V) R11 FSET 10µF /6.3V x2P C S Vout B 140 PGND PGND D1 L1 ISET VIN (3-4.2V) R 5, 60.4kΩ R4 10kΩ C3 1µF R6 R8 127kΩ 100kΩ Figure 3— Li-Ion Powered Display Application Circuit Example, 10 LED @ 40mA 20 SC5014A C8 L1 D1 R11 PGND R2 C6 R12 RCS C12 R1 OVP VCC IO1 UVLO R15 IO1 EN 2 0 kΩ FLT PGND R3 1 0 kΩ FLT SCL SCL SDA SDA PWM PWM IO2 S C 5014A IO2 PAD REF SCP ISET 2 .2 µF CS GND L2 Q1 NDRV VCC (5V) Vout C1 FSET VIN (6-27V) R5 R4 R8 C3 R6 1 µF Figure 4— SEPIC Configuration C1 R2 Q1 7 5 kΩ R3 VCC 10kΩ R12 20 WLEDs per channel 10kΩ IO1 EN 2 0 kΩ FLT SCL SCL SDA SDA PWM PWM SCP OVP IO1 UVLO R15 FLT 787kΩ 50m Ω R1 10kΩ CS 2 .2 µF 2 .2 µF /1 0 0 V x6P C S RCS C12 IO2 S C 5014A IO2 PAD REF GND C6 AON6482 NDRV VCC (5V) R11 FSET 1 0 µF /2 5 V x3P C S Vout up to 70V D FLS1100 PGND PGND D1 L1 3 .3 µH ISET VIN (12-19V) R 5 , 4 0 .2 k Ω R4 10kΩ C3 1 µF VIN R6 R8 2 5 .5 k Ω 2 5 0 kΩ Figure 5— Cascode Configuration drives 40 LEDs@200mA 21 SC5014A Serial Interface acknowledges and the master terminates the transfer with the stop condition [P]. The I2C General Specification The SC5014A is a read-write slave-mode I C device and complies with the NXP B.V. I2C standard Version 2.1, dated January 2000. The SC5014A has 11 user-accessible internal 8-bit registers. The I2C interface has been designed for program flexibility, supporting direct format for write operation. Read operations are supported on both combined format and stop separated format. While there is no auto increment/decrement capability in the SC5014A I2C logic, a tight software loop can be designed to randomly access the next register independent of which register you begin accessing. The start and stop commands frame the data-packet and the repeat start condition is allowed if necessary. 2 Limitations to the I2C Specifications The SC5014A only recognizes 7-bit addressing. This means that 10-bit addressing and CBUS communication are not compatible. The device can operate in either standard mode (100kbit/s) or fast mode (400kbit/s). Slave Address Assignment The 7-bit slave address is 0101 111x. The eighth bit is the data direction bit. 0x5F is used for read operation and 0x5E is used for write operation. (2) Combined Format — Read After the start condition [S], the slave address is sent, followed by an eighth bit indicating a write. The SC5014A I2C then acknowledges that it is being addressed, and the master responds with an 8-bit data byte consisting of the register address. The slave acknowledges and the master sends the repeated start condition [Sr]. Once again, the slave address is sent, followed by an eighth bit indicating a read. The slave responds with an acknowledge and the 8-bit data from the previously addressed register; the master then sends a non-acknowledge (NACK). Finally, the master terminates the transfer with the stop condition [P]. (3) Stop Separated Reads Stop-separated reads can also be used. This format allows a master to set up the register address pointer for a read and return to that slave at a later time to read the data. In this format the slave address followed by a write command are sent after a start [S] condition. The SC5014A then acknowledges it is being addressed, and the master responds with the 8-bit register address. The master sends a stop or restart condition and may then address another slave. After performing other tasks, the master can send a start or restart condition to the SC5014A with a read command. The device acknowledges this request and returns the data from the register location that had previously been set up. Supported Formats The supported formats are described in the following subsections. (1) Direct Format — Write The simplest format for an I2C write is direct format. After the start condition [S], the slave address is sent, followed by an eighth bit indicating a write. The SC5014A I2C then acknowledges that it is being addressed, and the master responds with an 8-bit data byte consisting of the register address. The slave acknowledges and the master sends the appropriate 8-bit data byte. Once again, the slave 22 SC5014A I2C Direct Format Write S S la ve A d d re ss W A R e g iste r A d d re ss A D a ta A P Slave Address – 7-bit R egister address – 8-bit D ata – 8-bit S – Start C ondition W – W rite = ‘0’ A – Acknow ledge (sent by slave ) P – Stop condition I2C Stop Separated Format Read M a ste r A d d re sse s o th e r S la ve s R e g iste r A d d re ss S e tu p A cce ss S S la ve A d d re ss W A R e g iste r A d d re ss A P S – Start C ondition W – W rite = ‘0’ R – R ead = ‘1’ A – Acknow ledge (sent by slave ) N AK – N on-Acknow ledge (sent by m aster) Sr – R epeated Start condition P – Stop condition S S la ve A d d re ss B R e g iste r R e a d A cce ss S/Sr S la ve A d d re ss R A D a ta N AC K P Slave Address – 7-bit R egister address – 8-bit D ata – 8-bit I2C Combined Format Read S S la ve A d d re ss W A R e g iste r A d d re ss S – Start C ondition W – W rite = ‘0’ R – R ead = ‘1’ A – Acknow ledge (sent by slave ) N AK – N on-Acknow ledge (sent by m aster) Sr – R epeated Start condition P – Stop condition A Sr S la ve A d d re ss R A D a ta N AC K P Slave Address – 7-bit R egister address – 8-bit D ata – 8-bit 23 SC5014A Register Map Address Bit 7 0x00 CLF Bit 6 Bit 5 Bit 4 LED_ SHORT LED_ OPEN 0x02 IDAC4 Bit 3 IDAC3 Bit 2 Bit 1 Bit 0 Reset Value Description OTP OVP FAULT 0x00 Fault Status IDAC2 IDAC1 IDAC0 0x1F Analog Dimming Control Definition of Registers and Bits Fault Status Register Bit Field Definition Read / Write Description 0x00 [7] CLF W Clear latching flags bit. (Set = 1 to clear OTP, LED_OPEN, LED_SHORT and mask OVP for 32 to 64μs) 0x00 [5] LED_SHORT R One or more LED strings faulted shorted 0x00 [4] LED_OPEN R One or more LED strings faulted open 0x00 [2] OTP R Thermal shutdown (1 = thermal OTP fault) 0x00 [1] OVP R Output over-voltage fault ( 1 = OVP ) 0x00 [0] FAULT R OR of all fault conditions (0= no fault, 1 = fault condition) Analog Dimming Control Register Bit Field Definition 0x02 [4:0] IDAC [4:0] Read / Write Description R/W 5-bit analog dimming register — The LED current can adjusted in 32 steps from 0mA to max value determined by RISET. 24 SC5014A Outline Drawing — MLPQ-20 4x4 A B D P IN 1 IN D IC A T O R (L A S E R M A R K ) D IM E N S IO N S IN C H E S M IL L IM E T E R S D IM M IN N O M M A X M IN N O M M A X A A1 A2 b D D1 E E1 e L N aaa bbb E A2 A .0 3 1 .0 3 5 .0 3 9 .0 0 0 .0 0 1 .0 0 2 - (.0 0 8 ) .0 0 7 .0 1 0 .0 1 2 .1 5 4 .1 5 7 .1 6 1 .1 0 0 .1 0 6 .1 1 0 .1 5 4 .1 5 7 .1 6 1 .1 0 0 .1 0 6 .1 1 0 .0 2 0 B S C .0 1 2 .0 1 6 .0 2 0 20 .0 0 4 .0 0 4 0 .8 0 0 .9 0 1 .0 0 0 .0 0 0 .0 2 0 .0 5 - (0 .2 0 ) 0 .1 8 0 .2 5 0 .3 0 3 .9 0 4 .0 0 4 .1 0 2 .5 5 2 .7 0 2 .8 0 3 .9 0 4 .0 0 4 .1 0 2 .5 5 2 .7 0 2 .8 0 0 .5 0 B S C 0 .3 0 0 .4 0 0 .5 0 20 0 .1 0 0 .1 0 S E A T IN G P LAN E aaa C A1 C D1 L xN E /2 E1 2 1 N b xN e bbb C A B D /2 NOTES: 1 . C O N T R O L L IN G D IM E N S IO N S A R E IN M IL L IM E T E R S (A N G L E S IN D E G R E E S ). 2 . C O P L A N A R IT Y A P P L IE S T O T H E E X P O S E D P A D A S W E L L A S T H E T E R M IN A L S . 25 SC5014A Land Pattern — MLPQ-20 4x4 K D IM E N S IO N S (C ) G H Y Z D IM C G H K P X Y Z IN C H E S (.1 56) .1 22 .1 06 .1 06 .0 20 .0 10 .0 33 .1 89 M IL LIM E T E R S (3 .95) 3 .10 2 .70 2 .70 0 .50 0 .25 0 .85 4 .80 X P NOTES: 1. T H IS L A N D P A T T E R N IS F O R R E F E R E N C E P U R P O S E S O N LY . C O N S U L T Y O U R M A N U F A C T U R IN G G R O U P T O E N S U R E Y O U R C O M P A N Y 'S M A N U F A C T U R IN G G U ID E LIN E S A R E M E T . 2. T H E R M A L V IA S IN T H E L A N D P A T T E R N O F T H E E X P O S E D P A D S H A L L B E C O N N E C T E D T O A S Y S T E M G R O U N D P LA N E . F A IL U R E T O D O S O M A Y C O M P R O M IS E T H E T H E R M A L A N D /O R F U N C T IO N A L P E R F O R M A N C E O F T H E D E V IC E . 26 SC5014A © Semtech 2012 All rights reserved. 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. No liability will be accepted by the publisher for any consequence of its use. Publication thereof does not convey nor imply any license under patent or other industrial or intellectual property rights. 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