CAT4101 1 A Constant-Current LED Driver with PWM Dimming Description The CAT4101 is a constant−current sink driving a string of high−brightness LEDs up to 1 A with very low dropout of 0.5 V at full load. It requires no inductor, provides a low noise operation and minimizes the number of components. The LED current is set by an external resistor connected to the RSET pin. The LED pin is compatible with high voltage up to 25 V, allowing the driving of long strings of LEDs. The device ensures an accurate and regulated current in the LEDs independent of supply and LED forward voltage variation. The PWM/EN input allows the device shutdown and the LED brightness adjustment by using an external pulse width modulation (PWM) signal. The driver features a thermal shutdown protection that becomes active whenever the die temperature exceeds 150°C. The device is available in a high−power, 5−lead TO−263 package offering excellent thermal dissipation characteristics. Features • • • • • • • • • Accurate 1 A Current Sink Up to 25 V Operation on LED Pin Low Dropout 500 mV at 1 A LED Current Set by External Resistor High Resolution PWM Dimming via EN/PWM “Zero” Current Shutdown Mode Thermal Shutdown Protection TO−263 5−lead Package These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS Compliant http://onsemi.com TO−263 TV SUFFIX CASE 221AE PIN CONNECTIONS 1 EN/PWM VIN TAB GND RSET LED (Top View) MARKING DIAGRAM CAT4101TV 3LYMXXXXA Applications • High Power LED up to 1 A • Architectural and General Lighting • Automotive Lighting VCC 3 V to 25 V VIN 5V OFF ON 549 W CAT4101TV = Specific Device Code 3 = Lead Finish (Matte−Tin) L = Assembly Location Code Y = Production Year (Last Digit) M = Production Month (1−9, A, B, C) XXXX = Last Four Digits of Assembly Lot Number A = Production Revision (Fixed as “A”) LEDs 1A VIN CAT4101 EN/PWM LED ORDERING INFORMATION RSET GND Device CAT4101TV−T75 (Note 1) Figure 1. Typical Application Circuit © Semiconductor Components Industries, LLC, 2010 February, 2010 − Rev. 4 Package Shipping TO−263 (Pb−Free) 750/ Tape & Reel 1. Lead Finish Matte−Tin 1 Publication Order Number: CAT4101/D CAT4101 Table 1. ABSOLUTE MAXIMUM RATINGS Parameter Rating Units VIN, RSET, EN/PWM 6 V LED Voltage 25 V Storage Temperature Range −65 to +160 _C Junction Temperature Range −40 to +150 _C 300 _C Lead Temperature Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. Table 2. RECOMMENDED OPERATING CONDITIONS Parameter Rating Units VIN 3.0 to 5.5 V Ambient Temperature Range −40 to +85 _C Up to 1 A LED Pin Current NOTE: Typical application circuit with external components is shown on page 1. Table 3. ELECTRICAL OPERATING CHARACTERISTICS (Min and Max values in bold are over recommended operating conditions unless specified otherwise. Typical values are at VIN = 5.0 V, TAMB = 25°C) Symbol ILED−ACC Parameter LED Current Accuracy VDOUT Dropout Voltage VRSET RSET Pin Voltage IQ Quiescent Current IQSHDN REN/PWM VHI VLO Conditions VLED = 1 V, RSET = 1.47 kW Min Typ Max Units 315 350 385 mA VLED = 1 V, RSET = 750 W 700 VLED = 1 V, RSET = 549 W 1000 ILED = 1 A 500 1.17 Shutdown Current 1.20 No LED, RSET = Floating 0.8 No LED, RSET = 549 W 8.0 VEN = 0 V EN/PWM Pin − Pull−down resistance − Logic High Level − Logic Low Level mV 1.23 V mA 1 mA 0.4 kW V V 200 1.3 TSD Thermal Shutdown 150 _C THYS Thermal Hysteresis 20 _C ILED/IRSET VUVLO RSET to LED Current gain ratio 100 mA LED current Undervoltage lockout (UVLO) Threshold 400 2.0 http://onsemi.com 2 V CAT4101 Table 4. RECOMMENDED EN/PWM TIMING (For 3.0 V ≤ VIN ≤ 5.5 V, over full ambient temperature range −40°C to +85°C.) Symbol Name Conditions Min Typ Max Units TPS Turn−On time, EN/PWM rising to ILED from Shutdown ILED = 1 A ILED = 350 mA 1.6 1.1 ms TP1 Turn−On time, EN/PWM rising to ILED ILED = 1 A ILED = 350 mA 920 620 ns TP2 Turn−Off time, EN/PWM falling to ILED ILED = 1 A ILED = 350 mA 440 310 ns TR LED rise time ILED = 1 A ILED = 350 mA 840 390 ns TF LED fall time ILED = 1 A ILED = 350 mA 470 350 ns TLO EN/PWM low time 1 ms THI EN/PWM high time 5 ms TPWRDWN EN/PWM low time to shutdown delay 8 THI ms TPWRDWN TLO EN/PWM SHUTDOWN SHUTDOWN TP2 TF TPS TP1 TR ILED = (1.2 V / RSET) x 400 90% LED CURRENT 50% 50% 10% SHUTDOWN 0 mA 0 mA VIN QUIESCENT CURRENT SHUTDOWN 0 mA SHUTDOWN Figure 2. CAT4101 EN/PWM Timing EN/PWM Operation The EN/PWM pin has two primary functions. One function enables and disables the device. The other function turns the LED channel on and off for PWM dimming control. The device has a very fast turn−on time (from EN/PWM rising to LED on) and allows “instant on” when dimming LED using a PWM signal. Accurate linear dimming is compatible with PWM frequencies from 100 Hz to 5 kHz for PWM duty cycle down to 1%. PWM frequencies up to 50 kHz can be supported for duty cycles greater than 10%. When performing a combination of low frequencies and small duty cycles, the device may enter shutdown mode. This has no effect on the dimming accuracy, because the turn−on time TPS is very short, in the range of 1 ms. To ensure that PWM pulses are recognized, pulse width low time TLO should be longer than 1 ms. The CAT4101 enters a “zero current” shutdown mode after a 5 ms delay (typical) when EN/PWM is held low. http://onsemi.com 3 CAT4101 TYPICAL PERFORMANCE CHARACTERISTICS (VIN = 5 V, VCC = 5 V, VF = 3.5 V, ILED = 1 A (1 LED), CIN = 1 mF, TAMB = 25°C unless otherwise specified.) 8.0 No Load QUIESCENT CURRENT (mA) QUIESCENT CURRENT (mA) 1.2 1.0 0.8 0.6 0.4 3.0 3.5 4.0 4.5 5.0 2.0 0 200 400 600 800 1000 INPUT VOLTAGE (V) LED CURRENT (mA) Figure 3. Quiescent Current vs. VIN Voltage (ILED = 0 mA) Figure 4. Quiescent Current vs. LED Current 1.2 Full Load 1.0 LED CURRENT (A) 8.0 7.5 7.0 0.8 0.6 0.4 0.2 6.5 3.0 3.5 4.0 4.5 5.0 0 5.5 0.3 0.6 0.9 1.2 LED PIN VOLTAGE (V) Figure 5. Quiescent Current vs. VIN Voltage (Full Load) Figure 6. LED Current vs. LED Pin Voltage 1.2 1.2 1.1 1.1 1.0 1.0 0.9 0.8 0.7 0.6 0.8 0.7 0.6 0.5 0.4 0.4 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0.3 5.5 −40 0 40 80 INPUT VOLTAGE (V) TEMPERATURE (°C) Figure 7. LED Current Change vs. VIN Voltage Figure 8. LED Current Change vs. Temperature http://onsemi.com 4 1.5 0.9 0.5 0.3 0 INPUT VOLTAGE (V) LED CURRENT (A) QUIESCENT CURRENT (mA) 4.0 0 5.5 8.5 LED CURRENT (A) 6.0 120 CAT4101 TYPICAL PERFORMANCE CHARACTERISTICS 1.30 1.30 1.25 1.25 RSET VOLTAGE (V) RSET VOLTAGE (V) (VIN = 5 V, VCC = 5 V, VF = 3.5 V, ILED = 1 A (1 LED), CIN = 1 mF, TAMB = 25°C unless otherwise specified.) 1.20 1.15 1.10 3.0 3.5 4.0 4.5 5.0 1.20 1.15 1.10 −40 5.5 0 40 80 120 INPUT VOLTAGE (V) TEMPERATURE (°C) Figure 9. RSET Pin Voltage vs. VIN Voltage Figure 10. RSET Pin Voltage vs. Temperature 1.2 LED CURRENT (A) 1.0 0.8 0.6 0.4 0.2 0 0 1 2 3 4 5 RSET (kW) Figure 11. LED Current vs. RSET Resistor Figure 12. PWM 200 Hz, 1% Duty Cycle 1.4 ENABLE THRESHOLD (V) LED CURRENT (%) 100 10 1 100 Hz 0.1 1 kHz 0.1 5 kHz 1 50 kHz 10 1.2 25°C 85°C 0.8 0.6 0.4 100 −40°C 1.0 3.0 3.5 4.0 4.5 5.0 DUTY CYCLE (%) INPUT VOLTAGE (V) Figure 13. LED Current vs. PWM Duty Cycle Figure 14. EN/PWM Threshold vs. VIN http://onsemi.com 5 5.5 CAT4101 Table 5. PIN DESCRIPTIONS Name Pin Function EN/PWM 1 Device enable (active high) and PWM control. VIN 2 Device supply input, connect to battery or supply. GND 3 Ground reference. RSET 4 A resistor connected between this pin and ground sets the LED current. LED 5 Bottom LED cathode terminal. TAB – Connect TAB to the Ground plane. Pin Function VIN is the supply pin for the device. A small 0.1 mF ceramic bypass capacitor is optional for noisy environments. The maximum operating voltage is 6.0 V. Whenever the input supply falls below the under−voltage threshold, the current sink will automatically be disabled. EN/PWM is the enable and one wire dimming input for the LED channel. Guaranteed levels of logic high and logic low are set at 1.3 V and 0.4 V respectively. When EN/PWM is initially taken high, the device becomes enabled and the LED current is set at a gain of 400 times the current in RSET. To place the device into zero current shutdown mode, the EN/PWM pin must be held low for 5 ms typical. LED pin is connected to the bottom LED cathode and provides a regulated current sink. The pin enters a high−impedance zero−current state whenever the device is placed in shutdown mode. RSET pin is connected to an external resistor to set the LED current. The ground side of the external resistor should be star connected to the GND of the PCB. The pin source current mirrors the current to the LED sink. The voltage at this pin is regulated to 1.2 V. GND is the ground reference for the device. The pin must be connected to the ground plane on the PCB. TAB is the exposed pad underneath the package. For best thermal performance, the tab should be soldered to the PCB and connected to the ground plane. http://onsemi.com 6 CAT4101 Block Diagram VIN LED VIN EN/PWM Undervoltage & Thermal Lockout Shutdown Delay Reference Voltage RSET Current Regulator RSET Regulator & Mirror GND Figure 15. CAT4101 Functional Block Diagram Basic Operation The CAT4101 has one highly accurate LED current sink to regulate LED current in a string of LEDs. The LED current is mirrored from the current flowing from the RSET pin. Table 6 lists various RSET resistor values for LED current in 100 mA increments. The LED channel needs a minimum of 500 mV headroom to sink constant regulated current. If the input supply falls below 2 V, the under−voltage lockout circuit disables the LED channel. For applications requiring current higher than 1 A, several CAT4101 devices can be connected in parallel. The LED channel can withstand and operate at voltages up to 25 V. This makes the device ideal for driving long strings of high power LEDs from a high voltage source. Table 6. RSET RESISTOR SETTINGS LED Current [mA] RSET [W] 100 4990 200 2490 300 1690 400 1270 500 1050 600 866 700 768 800 680 900 604 1000 549 http://onsemi.com 7 CAT4101 Application Information Single 12 V Supply For a given package style and board layout, the operating junction temperature TJ is a function of the power dissipation PD, and the ambient temperature, resulting in the following equation: The circuit shown in Figure 16 shows how to power three LEDs in series from a single 12 V supply using the CAT4101. The CAT4101 can not be driven directly from 12 V, three components are needed to create a lower voltage for the VIN pin (below 5.5 V). Resistor R2 and zener diode D provide a regulated voltage while the quiescent current runs through the N−Channel transistor M. Suitable parts for this circuit are the ON Semiconductor MM3Z6V2 zener diode and the 2N7002L N−channel transistor (SOT23 package). 12 V C2 1 mF R2 5 kW T J + TAMB ) P D(q JC ) q CA) + T AMB ) P D q JA The CAT4101 TO−263 5−lead package provides a thermal resistance when the ground tab is soldered down to the PCB. When mounted on a double−sided printed circuit board with two square inches of copper allocated for “heat spreading”, the resulting qJA is about 30°C/W. For example, at 60°C ambient temperature, the maximum power dissipation is calculated as follow: P Dmax + M D 6.2 V VIN C1 0.1 mF Recommended Layout LED The board layout should provide good thermal dissipation through the PCB. Multiple via can be used to connect the tab of the CAT4101 to a large ground plane underneath the package. Input capacitor C1 should be placed as close to the driver IC as possible. The RSET resistor should have a Kelvin connection to the GND pin of the CAT4101. CAT4101 EN/PWM R1 T Jmax * T AMB + 150 * 60 + 3 W 30 q JA RSET GND Figure 16. Single Supply Driving Three LEDs Power Dissipation The power dissipation (PD) of the CAT4101 can be calculated as follows: P D + (V IN I IN) ) (V LED ILED) where VLED is the voltage at the LED pin. Combinations of high VLED voltage or high ambient temperature can cause the CAT4101 to enter thermal shutdown. In applications where VLED is high, a resistor can be inserted in series with the LED string to lower PD. Thermal dissipation of the junction heat consists primarily of two paths in series. The first path is the junction to the case (qJC) thermal resistance which is defined by the package style, and the second path is the case to ambient (qCA) thermal resistance, which is dependent on board layout. The overall junction to ambient (qJA) thermal resistance is equal to: q JA + q JC ) q CA Figure 17. CAT4101 Recommended Layout http://onsemi.com 8 CAT4101 PACKAGE DIMENSIONS TO−263, 5 Lead CASE 221AE−01 ISSUE O E A c2 L1 D1 D H A1 PIN#1 ID c L e θ b TOP VIEW END VIEW Notes: (1) All dimensions are in millimeters. Angles in degrees. (2) Complies with JEDEC standard TO-263. http://onsemi.com 9 BOTTOM VIEW SYMBOL MIN A A1 b c c2 D D1 E e H L L1 q 4.20 0.00 0.60 0.33 1.15 8.40 6.86 9.80 NOM MAX 4.80 0.25 0.88 0.50 1.60 9.60 10.67 1.70 BSC 14.61 1.78 15.87 2.79 1.67 0º 8º CAT4101 Example of Ordering Information (Note 4) 2. 3. 4. 5. 6. Prefix Device # Suffix CAT 4101 TV− T75 Company ID (Optional) Product Number 4101 Package TV: TO−263 Tape & Reel (Note 6) T: Tape & Reel 75: 750 / Reel All packages are RoHS−compliant (Lead−free, Halogen−free). The standard plated finish is Matte−Tin. The device used in the above example is a CAT4101TV−T75 (TO−263, Tape & Reel, 750/Reel). For additional temperature options, please contact your nearest ON Semiconductor Sales office. For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. 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