KTD2531 KINETIC | Alldatasheet
Document overview
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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 − KTD2531: 36V − KTD2531B: 24V − KTD2531C: 19V High switching frequency − KTD2531: 900kHz − KTD2531B/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 KTD2531 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 KTD2531 to drive up to 36V output (10 LEDs in series), up to 24V using KTD2531B (6 LEDs in series) or up to 19V using KTD2531C (5 LEDs in series) . Alternatively, KTD2531 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 frequenc ies through the EN pin. Various protection features are built into the KTD2531, 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 KTD2531 is available in a RoHS compliant 6-lead TSOT23 package. Typical Application VIN LX Up to 10 in series or up to 3S 8P VIN 2.7V to 5.5V Enable Control EN VOUT GND CIN 10µF COUT 0.47µF L KTD2531 FB White LEDs VOUT up to 36V 10µH 10Ω 36V/24V/19V High Efficiency Step-Up LED Driver with PWM Control
November 2016 – Revision 04a Page 2 Company Confidential Pin Descriptions TSOT23-6 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
6 VIN IC supply voltage
(Top View) KTD2531 LX GND VIN FB EN VOUTKTD2531B KTD2531C
November 2016 – Revision 04a Page 3 Company Confidential Absolute Maximum Ratings 1 (TA=25C unless otherwise noted) Symbol Description Value Units VIN Input voltage -0.3 to 6.0 V VOUT Output voltage KTD2531 -0.3 to 44 V KTD2531B -0.3 to 30 KTD2531C -0.3 to 24 LX Switching node2 KTD2531 -1.2 to 44 V KTD2531B -1.2 to 30 KTD2531C -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 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions 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 ΔP/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) Marking Operating Temperature Package KTD2531EHD-TR 36V FBYYZ4 -40˚C to +85°C TSOT23-6 KTD2531BEHD-TR 24V __YYZ4 -40˚C to +85°C TSOT23-6 KTD2531CEHD-TR 19V __YYZ4 -40˚C to +85°C TSOT23-6 4. “YYZ” is the date code and assembly code.
November 2016 – Revision 04a Page 4 Company Confidential Electrical Characteristics 5 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 KTD2531, VIN = 4V, 8 LEDs, ILED = 20mA, L = 10uH, COUT = 0.1uF 350 mA KTD2531B, VIN = 4V, 6 LEDs, ILED = 20mA, L= 10uH, COUT = 0.47uF 280 KTD2531C, VIN = 4V, 4 LEDs, ILED = 20mA, L = 10uH, COUT = 0.47uF 200 IINRUSH-OL Peak Inductor Current During Open- Load Condition KTD2531, VIN = 4V, L = 10uH, COUT = 0.1uF, VOVP = 36V 150 mA KTD2531B, VIN = 4V, L = 10uH, COUT = 0.47uF, VOVP = 24V 140 KTD2531C, VIN = 4V, L = 10uH, COUT = 0.47uF, VOVP = 19V 120 FSW Oscillator frequency KTD2531 0.9 MHz KTD2531B 1.1 KTD2531C 1.1 Dmax Maximum duty cycle 92 95 % OVP Over voltage threshold Measured at VOUT pin KTD2531 36 V KTD2531B 24.4 KTD2531C 18.6 Control TS Start-up time 2000 s 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 KTD2531 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.
November 2016 – Revision 04a Page 5 Company Confidential Typical Characteristics VIN = 3.6V, L = 10H, CIN = 10F, COUT = 0.47F with 10 LEDs in series at 20mA, TAMB = 25°C unless otherwise specified. Efficiency vs. Input Voltage Efficiency vs. LED Current Operating Current (non-switching) Operating Current (switching) Switching Frequency EN Logic Threshold Voltage Efficiency (%) Input Voltage (V)
4 LEDs
10 LEDs
8 LEDs
6 LEDs
0 3 6 9 12 15 18 21 24 27 30 Efficiency (%) LED Current (mA) 0.20 0.25 0.30 0.35 0.40 0.45 0.50 Quiescent Current (mA) Input Voltage (V) 0.7 0.8 0.9 1.0 1.1 1.2 1.3 Quiescent Current (mA) Input Voltage (V) 800 850 900 950 1,000 Switching Frequency (KHz) Input Voltage (V) 0.6 0.7 0.8 0.9 1.0 1.1 Logic Threshold Voltage (V) Input Voltage (V) High Low
November 2016 – Revision 04a Page 6 Company Confidential Typical Characteristics (continued) VIN = 3.6V, L = 10H, CIN = 10F, COUT = 0.47F with 10 LEDs in series at 20mA, TAMB = 25°C unless otherwise specified. Steady State Switching Soft Start Turn On PWM Dimming (10kHz) Turn On with LED Open (OVP) EN PWM Dimming (20kHz) 0 25 50 75 100 LED Current (mA) EN PWM Duty Cycle (%)
November 2016 – Revision 04a Page 7 Company Confidential Functional Block Diagram Functional Description The KTD2531 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 KTD2531 operation. The beginning of each cycle turns on the Power MOSFET. 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 of 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 KTD2531 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 KTD2531 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 will 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
November 2016 – Revision 04a Page 8 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, 4.7 µH to 10µH inductor is recommended. If high efficiency is a critical requirement, a low DCR inductor should be selected. The inductor’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 like 3S8P, larger value output capacitors of 2.2µF is recommended to minimize the output ripple. Table 2. Recommended Ceramic Capacitor Vendors converter. The voltage rating should also exceed the target output voltage. Table 3. Recommended Schottky Diodes
Table 4. Current Setting Resistor (1% Values)
- Using a PWM Signal to EN Pin
corresponds to zero LED current. A 100% duty cycle PWM signal turns on the LEDs continuously at full current. average output current is continuously proportional to the PWM control signal regardless of the ripple amplitude. For systems which are sensitive to audible noise, it is recommended to use PWM frequencies greater than 5kHz.
Figure 9. Dimming Control using Digital Serial Interface Table 5. KTD100 Series Current Sink ICs for use with Dimming Control Method #5
sensitive node and it should be kept separate from the LX switching node in the PCB layout. Figure 10. Recommended PCB layout
November 2016 – 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°