CN5501

CONSONANCE High-Voltage, Linear High-Brightness LED Driver IC CN5501 General Description: Features: The CN5501 current regulator operates from a 4V to 32V input voltage range and delivers up to a total of 1A to one or more strings of high-brightness LEDs. The output current of the CN5501 is adjusted by using an external current-sense resistor in series with the LEDs. An enable input allows wide-range “pulsed” dimming. The CN5501 is well suited for applications requiring high-voltage input and is able to withstand automotive load-dump events up to 32V. An on-chip power MOSFET minimizes external components while providing ±5% output current accuracy. Also an EQ pin is adopted for equalizing LED current among multiple CN5501 used in parallel. Additional features include a 5V regulated output and thermal regulation, etc. The CN5501 is available in a thermally enhanced 8-pin SOP package and 8-pin DFN package.            Pin Assignment EQ 1 Applications:      8 NC 7 VCC GND 3 6 VIN CS 4 5 LED EN 2 Lighting Systems Automotive Interior and Exterior Navigation indicators Instrumentation illumination Signage and Beacons www.consonance-elec.com 4V to 32V Operating Voltage Adjustable LED Current up to 1A Integrated 32V, 1A MOSFET with 1.5A Current Limit(Typical) Low Current-Sense Voltage Reduces Power Loss Typical 5% LED Current Accuracy High-Voltage Chip Enable Input for Dimming Interface Current Equalizing Among Multiple CN5501 Used in Parallel Thermal Regulation Operating Temperature Range: －40℃ to 85℃ Available in Thermally-enhanced 8 pin SOP or 8-pin DFN package. Pb-free，Rohs Compliant and Halogen Free 1 CN5501 REV 1.0 CONSONANCE Typical Application Circuit Figure 1 Typical Application Circuit Ordering Information Part Number CN5501 www.consonance-elec.com Package SOP-8 DFN-8 Shipping Tape and Reel, 2500/Reel Tape and Reel, 5000/Reel 2 　Operating temperature －40℃ to 85℃ REV 1.0 CONSONANCE Pin Description Pin No. Name Function Description 1 EQ LED Current Equalizing Pin. This pin should be connected to other CN5501’s EQ pin for equalizing LED current when multiple CN5501 are used in parallel to drive multiple LED strings. 2 EN High Voltage Enable Pin. Drive EN pin to high to enable the output. 3 GND Ground Terminal. This pin is the negative terminal of input supply. LED Current Sense Pin. The LED current is sensed and set by the resistor between CS pin and GND. The equation to calculate the LED current is: 4 CS Where, ILED ＝ 0.153÷(RCS＋0.03) ILED is the LED current in ampere(A) RCS is the resistance from CS pin to GND in ohm(Ω) 5 LED Current Sink Pin. Drain of the on-chip power MOSFET，the LED string(s) should be connected between LED pin and VIN. 6 VIN Positive Terminal of Input Supply. This pin is the power supply of internal circuit. ＋5V Regulator Output Pin. A voltage of 5V(Typical) is output out of this 7 VCC 8 NC No Connection. - EP Exposed Pad. Connect to the GND plane for effective power dissipation. Do not use as the only ground connection. pin with 3mA output capability. Connect a 2.2μF to 10uF compensation capacitor from VCC pin to GND. Absolute Maximum Ratings VIN, EN and LED Pin Voltage…..…－0.3V to 36V Other Pins Voltage…….…….……..－0.3V to 6.5V Thermal Resistance(Junction to Case) …....65℃/W Lead Temperature(Soldering)……………….260℃ Operating Temperature…............－40℃ to 85℃ Maximum Junction Temperature………….150℃ Storage Temperature………......－65℃ to 150℃ Stresses beyond those listed under ‘Absolute Maximum Ratings’ may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to Absolute Maximum Rating Conditions for extended periods may affect device reliability. www.consonance-elec.com 3 REV 1.0 CONSONANCE Electrical Characteristics (VIN＝15V, TA＝－40℃ to 85℃, unless otherwise noted) Parameters Symbol Test Conditions Min Input Supply Voltage VIN 4 Operating Current IVIN VEN＝VIN, no LED current Shutdown Supply Current ISD VEN≤0.3V VIN Under Voltage Lockout VUVLO VIN Under Voltage Lockout Hysteresis HUVLO 220 VEN=VIN and VIN rises from 2.5V until VCS >100mV Typ 320 2.85 Max Unit 32 V 420 uA 3 uA 3.35 V 0.22 V CURRENT REGULATION The CS pin voltage VCS RCS＝3Ω, normal operation LED pin Leakage ILKG VIN＝32V, VEN＝0V Current Limit ILIMIT Dropout Voltage (Note 1) VDROP 144 1.15 152 160 mV 10 uA 1.5 ILED＝100mA 0.18 ILED＝300mA 0.36 ILED＝500mA 0.5 ILED＝750mA 0.7 ILED＝1A 0.9 2  V Thermal Regulation Thermal Regulation Temperature TREG 110 EN Input Voltage High VIH 3.1 EN Input Voltage Low VIL EN Bias Current IEN EN Turn-on Time tON 125 140 O C EN Pin V －100 EN’s rising edge to 90% of LED current 0.6 V ＋100 nA 270 uS ＋5V Regulator(VCC Pin) VCC Voltage VCC Short Circuit Current 0≤IVCC≤2mA, VIN≥5.5V VCC＝0V 4.7 5 5.35 4.4 V mA Note 1: Dropout voltage is measured across LED pin and CS pin when LED current is decreased by 5%. Detailed Description The CN5501 is a high-current regulator capable of providing up to a total of 1A of current to one or more strings of high-brightness LEDs. A wide operating input voltage range of +4V to +32V makes the CN5501 ideal for automotive applications. A +5V regulated output provides up to 3mA of current to power external circuitry. EQ pin can equalize the LED current among multiple CN5501 used in parallel to drive multiple LED strings. In addition, the CN5501 features thermal regulation instead of thermal shutdown. If the voltage drop across LED pin and CS pin is high, or the LED current is large, or both the voltage drop and LED current are large, CN5501 will become heater, when the silicon temperature reaches 125℃, the on-chip thermal regulation circuit begins to function, the LED current will be decreased to keep CN5501’s silicon temperature at 125℃(typical). www.consonance-elec.com 4 REV 1.0 CONSONANCE The wide operating voltage range helps protect the CN5501 against large transients such as those found in load-dump situations up to 32V. The CN5501 uses a feedback loop to control the LED current. The voltage across the sense resistor RCS is compared to a fixed reference voltage, and the error is amplified to serve as the drive to the internal power MOSFET. The regulated LED current is user defined by the value of RCS between CS pin and GND. Application Information Input Voltage Considerations The operating voltage range of the CN5501 is ＋4V to ＋32V . The device may operate below +4V, however, LED current may not meet the full regulation specification. For proper operation, the minimum input voltage must always be higher than the worst-case sum of the forward drops of all series-connected LEDs at the output of the CN5501. +5V Regulator The CN5501 includes a fixed +5V output regulator that delivers up to 3mA of load current for low-power applications throughout the +5.5V to +32V input voltage range. Connect a 2.2μF to 10uF compensation capacitor from VCC pin to GND. The +5V output can be used to power the external circuitry. Thermal Regulation The CN5501 features thermal regulation instead of thermal shutdown. If the voltage drop across LED pin and CS pin is high, or the LED current is large, or both the voltage drop and LED current are large, CN5501 will become heater, when the silicon temperature reaches 125℃, the on-chip thermal regulation circuit begins to function, the LED current will be decreased to keep the silicon temperature at 125℃(typical). This typically occurs in overload or LED short-circuit conditions. Setting the LED Current The CN5501 uses a current sense resistor between CS pin and GND to set the LED current. The LED current is given by the equation below: ILED＝0.153÷(RCS＋0.03) Where, ILED is the LED current in ampere(A) RCS is the resistance from CS pin to GND in ohm(Ω) PWM Dimming The CN5501 provides pulsed or chopped current dimming. Generally, high-brightness LEDs are binned to match at their full-rated current. However, LEDs from the same bin exhibit poor matching at currents other than full-rated current. To achieve uniformity, high brightness LED manufacturers recommend PWM pulsing of the LED current at their full-rated value. This can be achieved by pulsing the enable input (EN) while having a constant voltage at VIN, as shown in Figure 2. The PWM signal frequency should be less than 300Hz. www.consonance-elec.com 5 REV 1.0 CONSONANCE Figure 2 PWM Dimming Driving Multiple LED Strings When multiple LED strings need to be driven, multiple CN5501 can be used in parallel, each CN5501 drives one LED string. In this case, the current flowing through each LED string can be equalized by connecting every CN5501’s EQ pin together, as shown in Figure 3. Figure 3 Multiple CN5501 Used In Parallel VIN Bypass Capacitor CIN In most applications, a high-frequency bypass capacitor at the input is needed. Generally A 1uF ceramic capacitor, placed in close proximity to VIN and GND pins, works well. In some applications depending on the power supply characteristics and cable length, it may be necessary to increase the capacitor's value. For the www.consonance-elec.com 6 REV 1.0 CONSONANCE consideration of the bypass capacitor, please refer to the Application Note AN102 from our website. PCB Layout Considerations 1. RCS at CS pin should be as close to CN5501 as possible. 2. The capacitor at VCC pin should be as close to CN5501 as possible. 3. It is very important to use a good thermal PC board layout to maximize LED current and minimize the drop out voltage. The thermal path for the heat generated by the IC is from the die to the copper lead frame, through the package lead(especially the ground lead) to the PC board copper, the PC board copper is the heat sink. The footprint copper pads should be as wide as possible and expand out to larger copper areas to spread and dissipate the heat to the surrounding ambient. Feedthrough vias to inner or backside copper layers are also useful in improving the overall thermal performance of the LED driver. Other heat sources on the board, not related to the LED driver, must also be considered when designing a PC board layout because they will affect overall temperature rise and the maximum LED current. The ability to deliver maximum LED current under all conditions require that the exposed metal pad on the back side of the CN5501 package be soldered to the PC board ground. Failure to make the thermal contact between the exposed pad on the backside of the package and the copper board will result in larger thermal resistance. www.consonance-elec.com 7 REV 1.0 CONSONANCE Package Information (SOP8) www.consonance-elec.com 8 REV 1.0 CONSONANCE Package Information (DFN-8) Consonance does not assume any responsibility for use of any circuitry described. Consonance reserves the right to change the circuitry and specifications without notice at any time. www.consonance-elec.com 9 REV 1.0