KTD2500 KINETIC | Alldatasheet
Document overview
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Technical content
Features
Wide output range: up to 10 series LEDs Integrated 40V high current switch (0.75A limit) VIN: 2.7V~5.5V High efficiency PWM converter (up to 88%) Low 200mV feedback voltage Single-wire interface dual method dimming: ExpressWire Digital Control PWM dimming High accuracy across full load range LED open-circuit (OVP) protection KTD2500: 38V KTD2500B: 26V High switching frequency: 600kHz Simple, small solution size Integrated Softstart < 1µA shutdown current Small TDFN22-6 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 KTD2500 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 0.75A current limit allow KTD2500 to drive up to 38V output (10 LEDs in series) or up to 26V using KTD2500B (6 LEDs in series). It can also maximize the current capability while achieving high conversion efficiency. The optimized 600kHz switching frequency results in reduced conduction loss and small external component size. A single-wire interface is integrated which can be used for PWM dimming or ExpressWire dimming in 32 steps. Various protection features are built into KTD2500, 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. KTD2500 is available in an RoHS and Green compliant 6- lead TDFN 2x2mm package. Typical Application VIN LX Up to 10 in series Input Range: 2.7V~5.5V CTRL COMP GND CIN COUT L FB White LEDs Up to 38V Output Brightness Control: ExpressWire Control or PWM dimming 38V/26V Step-Up LED Driver with PWM/ExpressWire™ Control
January 2016 – Revision 04m Page 2 Company Confidential kinetic technologies kinetic technologies Pin Descriptions TDFN22-6 Pin # Name Function
1 FB Output feedback pin
2 COMP
Converter compensation pin. Connect a capacitor from this pin to GND for loop compensation.
3 GND Converter/IC ground
Converter switching node. The inductor should be connected between VIN and LX. This pin is also used to sense the output for open-load protection.
5 CTRL
IC control pin. Can be used to enable/disable the IC, as well as to program the output current using ExpressWire or PWM dimming. This pin is bidirectional when the acknowledge programming bit is set, as it asserts an open drain acknowledge signal when a valid ExpressWire command is given.
6 VIN IC supply voltage
Top View: FB COMP GND VIN CTRL LX MC
January 2016 – Revision 04m Page 3 Company Confidential kinetic technologies kinetic technologies Absolute Maximum Ratings1 (TA=25C unless otherwise noted) Symbol Description Value Units VIN Input voltage -0.3 to 6.0 V LX Switching node2 KTD2500 -1.2 to 42 V KTD2500B -1.2 to 30 FB, CTRL, COMP 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 Thermal Capabilities Symbol Description Value Units TDFN22-6 θJA Thermal Resistance – Junction to Ambient3 65 C/W PD Maximum Power Dissipation at TA ≤ 25C 1.54 W ΔPD/C Derating Factor Above TA = 25C -15.4 mW/C
Ordering Information
(nominal) Marking4 Operating Temperature Package KTD2500ECD-TR 38V DRYYZ -40°C to +85°C TDFN22-6 KTD2500BECD-TR 26V DSYYZ -40°C to +85°C TDFN22-6 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. 3. Junction to Ambient thermal resistance is highly dependent on PCB layout. Values are based on thermal properties of the devic e when soldered to an EV board. 4. “YYZ” is the date code and assembly code.
January 2016 – Revision 04m Page 4 Company Confidential kinetic technologies kinetic technologies Electrical Characteristics5 Unless otherwise noted, the Min and Max specs are applied over the full operation temperature range of –40°C to +85°C, while Typ values are specified at room temperature (25°C). 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 0.37 0.6 mA IC operating current (switching) FB = 0V 0.8 1.6 mA ISHDN VIN pin shutdown current CTRL = GND 0.1 1.0 A Step-Up Converter VFB FB pin accuracy 184 200 216 mV VFB_DATA6 FB pin accuracy at Data 6 VFB = 20mV 14 20 26 mV 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 0.75 A FSW Oscillator frequency 600 kHz Dmax Maximum duty cycle 92 96 % VOVP Over voltage threshold Measured at LX pin KTD2500 38 V KTD2500B 26 tSTARTUP Start-up time CCOMP = 0.22µF 14 ms 5. KTD2500 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.
January 2016 – Revision 04m Page 5 Company Confidential kinetic technologies kinetic technologies Electrical Characteristics Continued6 Symbol Description Conditions Min Typ Max Units Control VTH-L CTRL logic low threshold 0.4 V VTH-H CTRL logic high threshold 1.4 V RCTRL CTRL pull down resistor 300 600 1200 kΩ toff CTRL pulse width to shutdown CTRL high to low 2.5 ms tEW_DET ExpressWire detection time7 260 s tEW_DELAY ExpressWire detection delay 100 s tEW_WIN ExpressWire detection window time 1 ms tSTART Start time of programming stream 2 s tEOS End time of programming stream 2 360 s tH_LB High time low bit Logic 0 2 180 s tL_LB Low time low bit Logic 0 2 x tH_LB 360 s tH_HB High time high bit Logic 1 2 x tL_HB 360 s tL_HB Low time high bit Logic 1 2 180 s VACK Acknowledge output voltage low Open drain, 15kΩ pull- up from CTRL to VIN 0.4 V tACK_VAL Acknowledge valid time Note 8 2 s tACK Duration of acknowledge condition Note 8 512 s fDIM Recommended PWM dimming frequency 5 100 kHz DPWM_MIN PWM dimming duty cycle resolution fDIM = 20kHz 1 % fDIM = 30kHz 1 % Thermal Shutdown TJ-TH IC junction thermal shutdown threshold 150 C IC junction thermal shutdown hysteresis 15 C 6. KTD2500 is guaranteed to meet performance specifications over the –40°C to +85°C operating temperature rang e by design, characterization and correlation with statistical process controls. 7. To select ExpressWire programming, the CTRL pin must be low for more than tEW_DET during tEW_WIN 8. Acknowledge condition is active 0, this condition will only be applied in case the RFA bit is set. The open drain output requires a pull-up resistor.
January 2016 – Revision 04m Page 6 Company Confidential kinetic technologies kinetic technologies Typical Characteristics VIN = 3.6V, ILED = 20mA, 10-Series LEDs, L = 22H, CIN = 4.7F, COUT = 1F, CCOMP = 0.22F, Temp = 25°C unless otherwise specified. Efficiency (20mA, L = 22µH) Operating Current (non-switching) Switching Frequency vs. Input Voltage Shutdown Delay vs. Input Voltage PWM Dimming Linearity (20kHz) ExpressWire Interface Programming Data Steps Efficiency (%) Input Voltage (V) 8LEDs 10LEDs 6LEDs 0.2 0.3 0.4 0.5 0.6 Quiescent Current (mA) Input Voltage (V) 600 610 620 630 640 650 660 670 680 690 700 Frequency (KHz) Input Voltage (V) 1.40 1.45 1.50 1.55 1.60 1.65 1.70 1.75 1.80 Shutdown Delay (ms) Input Voltage (V) 100 120 140 160 180 200 0 10 20 30 40 50 60 70 80 90 100 FB Voltage Rating (mV) PWM Duty Cycle (%) 100 120 140 160 180 200 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 FB Voltage (mV) Programming Data
January 2016 – Revision 04m Page 7 Company Confidential kinetic technologies kinetic technologies Typical Characteristics (continued) Soft Start Turn ON Shutdown Steady State Switching Turn ON with LED Open (OVP) PWM Dimming (10kHz, 50% Duty Cycle) Inductor Current 200mA / div 2ms / div FB 100mV / div VOUT 10V / div CTRL 5V / div Inductor Current 200mA / div 400µs / div FB 100mV / div VOUT 10V / div CTRL 5V / div Inductor Current 200mA / div 2µs / div VOUT AC Coupled 100mV / div LX 20V / div Inductor Current 100mA / div 1ms / div VOUT 10V / div CTRL 5V / div Inductor Current 200mA / div 100µs / div FB 100mV / div CTRL 5V / div VOUT AC Coupled 500mV / div
January 2016 – Revision 04m Page 8 Company Confidential kinetic technologies kinetic technologies Functional Block Diagram Functional Description KTD2500 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 KTD2500 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 (FB), so that FB voltage can be regulated to the reference voltage. KTD2500 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 KTD2500 include over-voltage protection (OVP) , cycle-by-cycle current limit protection and thermal shutdown. The control interface can be used for either PWM dimming or ExpressWire single-wire control. In ExpressWire mode, it accepts a data set into the CTRL pin to program the reference voltage. The data contains 5 bits, yielding 32 different current levels . In PWM dimming mode, PWM pulse s are provided at CTRL pin to program the reference voltage according to the duty cycle of the PWM signal, so that the LED current is proportional to the PWM duty cycle. The simple st control method is accomplished by toggling CTRL between high and low to program the output current between IMAX and 0mA. IMAX is set by the resistor connected between FB and GND. Please see LED Maximum Current Setting section in this document to determine the proper resistor value. KTD2500 has internal OVP circuitry to prevent IC damage during open-LED condition. When an LED fails open, the feedback voltage falls to zero, forcing the boost converter to operate in maximum duty cycle mode, ramping up the output voltage. LX pin’s peak voltage also goes up with the output voltage . KTD2500 monitors the LX pin’s peak voltage continuously and if it exceeds OVP threshold for at least 8 switching cycles, KTD2500 will Over voltage protection PWM Control and Gate Drive LX Voltage ReferenceCTRL FB VIN GND Oscillator Ramp Generator COMP gM VIN Current Sense Σ Current Sense Thermal Shutdown VIN Current Limit Input Logic and DAC COMP
and can be reset by either toggling the CTRL pin or powering down and powering up the IC. programming, the first few pulses at CTRL pin should meet the following timing requirement shown in Figure 1. Figure 1. Dimming Mode Selection Pulses
- After the IC is powered up, CTRL’s 1st pulse high width (ExpressWire detection delay time) tEW_DELAY
should be greater than 100µs.
- CTRL’s 1st pulse low width (ExpressWire detection time) tEW_DET should be greater than 260µs.
- The programming pulses should be started within the ExpressWire detection window tEW_WIN, which is
1ms. Otherwise the default setting or previous stored setting will be used to set the reference voltage.
- Driving CTRL low for more than 2.5ms to shut down the IC, then sending PWM signal (frequency range
down the IC will not reset the maximum reference voltage.
- Removing power from the IC and then reapplying power to perform power-on reset, then sending PWM
reset the maximum reference voltage.
shut down the IC will not reset the internal register. Table 1. FB Voltage Programing Table KTD2500’s ExpressWire programming protocol is a simple single -wire interface used to scale the FB voltage.
correctly. The control interface can automatically detect bit rates between 1.7kBit/sec and 160kBit/sec. Figure 2. ExpressWire Protocol Overview Table 2. ExpressWireProtocol Bit Description
7 DA7
6 DA6 1
5 DA5 1
4 DA4 1
3 DA3 0
2 DA2 0
1 DA1 1
0 DA0 0 (LSB device address)
6 A1 0, Register Address bit 1
5 A0 0, Register Address bit 0
4 D4 Data bit 4
3 D3 Data bit 3
2 D2 Data bit 2
1 D1 Data bit 1
0 EOS Start RFA A1 A0 D4 D3 D2 D1 D0 EOS
Table 4. Recommended Ceramic Capacitor Vendors converter. The voltage rating should also exceed the OVP threshold under open-load condition. Table 5. Recommended Schottky Diode Part Numbers recommended. The formula and table for R1 selection are shown below. Table 6. Current Setting Resistor (1% Values)
January 2016 – Revision 04m Page 14 Company Confidential kinetic technologies kinetic technologies Packaging Information TDFN22-6 Recommended Footprint Tape and Reel Orientation 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. D E L A Top View Bottom View Side View b Seating Plane e 5 6 3 2 1 TQFN22 (KTD2500) 2.50 1.65 * Dimensions are in millimeters. 0.35 0.65 0.58 1.0 1.35 Embossment Center Line of CavityUser Direction of Feed Dimension mm Min. Typ. Max. A 0.70 0.75 0.80 A3 0.2BSC b 0.25 0.30 0.35 D 1.90 2.00 2.10 D2 1.40 1.50 1.60 E 1.90 2.00 2.10 E2 0.80 0.90 1.00 e 0.65BSC L 0.20 0.25 0.30