KTD251 KINETIC | Alldatasheet
Document overview
- Manufacturer or author: Provided By alldatasheet.com(free datasheet download site)
- PDF pages: 15
Technical content
Features
- Wide output range: up to 10 series LEDs
- Integrated 40V high current switch (800mA limit)
- High efficiency PWM converter (up to 90%)
- Low 200mV feedback voltage
- High accuracy across full load range
- VIN range: 2.7V to 5.5V
- LED open-circuit (OVP) protection − KTD251: 36V − KTD251B: 24V − KTD251C: 19V
- High switching frequency − KTD251: 900kHz − KTD251B/C: 1.1MHz
- PWM dimming frequency: 100Hz to 200kHz
- Simple, small solution size
- Integrated Soft-start
- Shutdown Current less than 1µA
- Small TSOT23-6 Package
- RoHS and Green compliant
- -40°C to +85°C Temperature Range
Applications
- LED backlighting
- Mobile Phones
- Handheld Devices
- Digital Photo Frames
- Automotive Navigation Brief Description The KTD251 is a versatile constant current LED driver with a high efficiency DC-DC step up “boost” converter architecture. The low-side power MOSFET is integrated in the device , minimizing the total number of external components. Unique technology and high 800mA current limit allow KTD251 to drive up to 36V output (10 LEDs in series), up to 24V using KTD251B (6 LEDs in series) or up to 19V using KTD251C (5 LEDs in series) . Alternatively, KTD251 can deliver 160mA total current with 3 series LEDs per string. It can also maximize the current capability while achieving high conversion efficiency. The optimized 0.9MHz and 1.1MHz switching frequencies result in small external component size. The driver allows a wide range of PWM dimming frequencies through the EN pin. Various protection features are built into the KTD251, including cycle-by-cycle input current limit protection, LED open-circuit (output over voltage) protection and thermal shutdown protection. The leakage current in shutdown mode is less than 1µA. The KTD251 is available in a RoHS compliant 6-lead TSOT23 package. Typical Application VIN LX Up to 10 in series Or up to 3S 8P Input Range: 2.7V~5.5V Enable EN VOUT GND CIN COUT L KTD251 FB White LEDs Up to 36V Output 36V/24V/19V High Efficiency Step-Up LED Driver with PWM Control
May 2019 – Revision 04a Page 2 Company Confidential Pin Descriptions Pin # Name Function
1 LX Converter switching node
2 GND Converter/IC ground
3 FB Output feedback pin regulated at 0.2V 4 EN IC enable and PWM dimming control pin. A logic High signal enables converter. A PWM signal on this pin controls LED average conduction current.
5 VOUT Converter output and over-voltage protection sensing pin
6 VIN IC supply voltage
(Top View) KTD251 LX GND VIN FB EN VOUTKTD251B KTD251C
May 2019 – Revision 04a Page 3 Company Confidential Absolute Maximum Ratings1 (TA = 25C unless otherwise noted) Symbol Description Value Units VIN Input voltage -0.3 to 6.0 V LX, VOUT High voltage nodes KTD251 -0.3 to 44 V KTD251B -0.3 to 30 KTD251C -0.3 to 24 LX Switching node2 KTD251 -1.2 to 44 V KTD251B -1.2 to 30 KTD251C -1.2 to 24 FB, EN Other pins -0.3 to VIN+0.3 V TJ Operating Temperature Range -40 to 150 C Ts Storage Temperature Range -65 to 150 C TLEAD Maximum Soldering Temperature (at leads, 10 sec) 300 C ESD HBM electrical static discharge 2.0 kV 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at co nditions other than the operating conditions specified is not implied. Only one Absolute Maximum rating should be applied at any one time. 2. LX Switching node can tolerate Absolute Maximum negative voltage rating with maximum 100mA flowing from GND to LX pin. Thermal Capabilities Symbol Description Value Units θJA Thermal Resistance – Junction to Ambient3 190 C/W PD Maximum Power Dissipation at TA ≤ 25C 0.526 W ΔPD/C Derating Factor Above TA = 25C -5.26 mW/C 3. Junction to Ambient thermal resistance is highly dependent on PCB layout. Values are based on thermal properties of the device when soldered to an EV board.
Ordering Information
(nominal) Marking4 Operating Temperature Package KTD251EHD-TR 36V DJYYZ -40˚C to +85°C TSOT23-6 KTD251BEHD-TR 24V DKYYZ -40˚C to +85°C TSOT23-6 KTD251CEHD-TR 19V DLYYZ -40˚C to +85°C TSOT23-6 4. “YYZ” is the date code and assembly code.
May 2019 – Revision 04a Page 4 Company Confidential Electrical Characteristics5 Unless otherwise noted, t he Min and Max specs are applied over the full operation temp erature range of –40°C to +85°C, while Typ values are specified at room temperature (25C). VIN = 3.6V. Symbol Description Conditions Min Typ Max Units IC Supply VIN Input operating range 2.7 5.5 V UVLO Input under voltage lockout Rising edge 2.5 2.65 V UVLOHYST UVLO hysteresis 0.15 V IQ IC quiescent current (non switching) FB = 0.4V 0.28 0.5 mA IC operating current (switching) FB = 0V 0.7 1.65 mA ISHDN VIN pin shutdown current EN = GND 0.1 1.0 A Step-Up Converter VFB FB pin voltage accuracy 0.184 0.2 0.216 V IFB FB pin bias current 0.1 A RDS(ON) NMOS on-resistance TA = 25˚C 0.65 1.0 Ω ILX LX pin leakage current 0.1 A ILIM Peak NMOS current limit 800 mA IINRUSH-SU Peak Inductor Current During Startup KTD251, VIN = 4V, 8 LEDs, ILED = 20mA, L = 10µH, COUT = 0.1µF 350 mA KTD251B, VIN = 4V, 6 LEDs, ILED = 20mA, L = 10µH, COUT = 0.47µF 280 KTD251C, VIN = 4V, 4 LEDs, ILED = 20mA, L = 10µH, COUT = 0.47µF 200 IINRUSH-OL Peak Inductor Current During Open- Load Condition KTD251, VIN = 4V, L = 10µH, COUT = 0.1µF, VOVP = 36V 150 mA KTD251B, VIN = 4V, L = 10µH, COUT = 0.47µF, VOVP = 24V 140 KTD251C, VIN = 4V, L = 10µH, COUT = 0.47µF, VOVP = 19V 120 FSW Oscillator frequency KTD251 0.9 MHz KTD251B 1.1 KTD251C 1.1 Dmax Maximum duty cycle 92 95 % OVP Over voltage threshold Measured at VOUT pin KTD251 36 V KTD251B 24.4 KTD251C 18.6 TS Start-up time 2000 s Control VTH-L Logic low threshold 0.4 V VTH-H Logic high threshold 1.4 V TOFF EN low to shutdown time 3 ms FEN Dimming frequency 0.1 200 kHz TJ-TH IC junction thermal shutdown threshold 150 C IC junction thermal shutdown hysteresis 15 C 5. The KTD251 is guaranteed to meet performance specifications over the –40°C to +85°C operating temperature range by design, characterization and correlation with statistical process controls.
May 2019 – Revision 04a Page 5 Company Confidential Typical Characteristics VIN = 3.6V, ILED = 20mA, 6 -Series LEDs, L = 22H, Cin = 10F, Cout = 0.47F, Temp = 25ºC unless otherwise specified. Efficiency (20mA, L = 4.7µH) Efficiency (20mA, L = 10µH) Operating Current (non-switching) Operating Current (non-switching) vs. Temperature KTD251 Switching Frequency vs. Input Voltage KTD251B/C Switching Frequency vs. Input Voltage 100 Efficiency (%) Input Voltage (V)
10 LEDs
(Vout=32.1V) R1 = 10Ω
8 LEDs
(Vout=25.8V)
4 LEDs
(Vout=13.0V) 6 LEDs (Vout=19.4V) 100 Efficiency (%) Input Voltage (V) (Vout=32.1V) R1 = 10Ω (Vout=25.8V) (Vout=13.0V) 6 LEDs (Vout=19.4V) 200 250 300 350 400 2.5 3 3.5 4 4.5 5 5.5 Iq (uA) Input Voltage (V) 200 250 300 350 400 -40 -20 0 20 40 60 80 100 120 140 Quiescent Current (uA) Temperature (C) 700 750 800 850 900 950 1000 3 3.5 4 4.5 5 5.5 Switching Frequency (kHz) Input Voltage (V) 900 950 1000 1050 1100 1150 1200 3 3.5 4 4.5 5 5.5 Switching Frequency (kHz) Input Voltage (V)
May 2019 – Revision 04a Page 6 Company Confidential Typical Characteristics (continued) KTD251 Switching Frequency vs. Temperature KTD251B/C Switching Frequency vs. Temperature 600 700 800 900 1000 -40 -20 0 20 40 60 80 100 120 140 Switching Frequency (kHz) Temperature (C) 850 900 950 1000 1050 1100 1150 -40 -20 0 20 40 60 80 100 120 140 Switching Frequency (kHz) Temperature (C)
May 2019 – Revision 04a Page 7 Company Confidential Typical Characteristics (continued) Steady State Switching Soft Start Turn ON Shutdown KTD251 Turn ON with LED Open (OVP) PWM Dimming (200Hz) PWM Dimming (200kHz) (1us/div) CH1: LX (10V/div) CH2: VOUT AC Coupled (1V/div) CH4: IL (200mA/div) (500us/div) CH2: VOUT (10V/div) CH3: IIN (100mA/div) CH4: VFB (100mV/div) CH1: VEN (2V/div) (400us/div) CH2: VOUT (10V/div) CH3: IL (100mA/div ) CH4: LX (10V/div) CH1: VEN (5V/div) (200us/div) CH2: VOUT (10V/div) CH3: IL (200mA/div) CH4: LX (10V/div) CH1: VEN (5V/div) (2ms/div) CH2: VOUT (10V/div) CH3: ILED (10mA/div) CH1: VEN (5V/div) (10us/div) CH2: VOUT (10V/div) CH3: ILED (10mA/div) CH1: VEN (5V/div)
May 2019 – Revision 04a Page 8 Company Confidential Functional Block Diagram Functional Description The KTD251 uses a constant -frequency current-mode boost converter architecture to control the LED current by regulating the feedback voltage . Please refer to the functional block diagram above for an explanation of KTD251 operation. The beginning of each cycle turns on the Power MOS FET. A slope compensation ramp is added to the output of the current sense amplifier and the result is fed into the positive input of the comparator (COMP). When this voltage goes above the output voltage o f the error amplifier (gM), the Power MOSFET is turned off. The voltage at the output of the gM block amplifies the difference between the reference voltage and the feedback voltage (VFB), so that FB pin voltage can be regulated to the reference voltage. The KTD251 has built-in soft-start to limit the inrush current during startup and to limit the amount of overshoot on the output. Protection features in the KTD251 include over -voltage protection (OVP) , cycle-by-cycle current limit protection and thermal shutdown. OVP protects in the event where an LED fails open, which forces the feedback voltage to zero. This causes the boost converter to operate in maximum duty cycle mode, ramping up the output voltage. Switching wi ll stop when the output reaches the OVP threshold. The OVP feature protects the IC from damaging itself by exceeding the voltage rating on LX/VOUT pins. Over voltage protection PWM Control and Gate Drive LX Voltage Reference 200mV EN FB VIN GND VIN Oscillator Ramp Generator COMP gM VOUT Current Sense Σ Current Sense Thermal Shutdown VIN Current LimitInput Logic and Low Pass Filter 3ms Delay Shutdown
May 2019 – Revision 04a Page 9 Company Confidential
Application Information
A 4.7µH to 22µH inductor is recommended for 6/5/4-Series LED applications and 3S8P LED applications. For 7 or more LEDs in series, 4.7µH to 10µH inductor is recommended. If high efficiency is a critical requirement, a low DCR inductor should be selected. The i nductor’s saturation current rating should also exceed the peak input current, especially for high load current application (like 3S8P). Table 1. Recommended Inductor Part Numbers capacitors like 2.2µF is recommended to minimize output ripple. Table 2. Recommended Ceramic Capacitor Vendors reverse recovery time. The current rating of the schottky diode should exceed the peak current of the boost converter. The voltage rating should also exceed the target output voltage. Table 3. Recommended Schottky Diode Part Numbers
The LED current is determined by the feedback resistor R1. The feedback voltage (VFB) is internally set at 200 mV. settings, precision 1% resistors are recommended. The formula and table for R1 selection are shown below. Table 4. Current Setting Resistor (1% Values)
- Using a PWM Signal to EN Pin
With the PWM signal applied to the EN pin, the KTD251 is correspondingly turned ON or OFF by the PWM signal. noise, it is recommended to use PWM frequencies greater than 5kHz. For some applications, the preferred method of brightness control is a variable DC voltage to adjust the LED current.
May 2019 – Revision 04a Page 15 Company Confidential Packaging Information TSOT23-6 Recommended Footprint Kinetic Technologies cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Kinetic Technologies product. No intellectual property or circuit patent licenses are implied. Kinetic Technologies reserves the right to change the circuitry and specifications without notice at any time. Top View End ViewSide View e b D E1 E A1 A θ C L 3.84 * Dimensions are in millimeters. 0.62 0.95 1.22 1.40 Dimension mm Min. Typ. Max. A 0.60 0.85 1.10 A1 0.00 0.05 0.10 b 0.30 0.40 0.50 c 0.10 0.15 0.20 D 2.70 2.90 3.10 E 2.60 2.80 3.00 E1 1.40 1.60 1.80 e 0.95BSC e1 1.9BSC L 0.30 0.60 θ 4° 12°