FP6395D7

FP6395 High Efficiency 1.5MHz 1.2A Synchronous Step Down LED Driver Description Features The FP6395 is a high efficiency, high frequency synchronous DC-DC step-down LED driver. The 100% duty cycle feature provides low dropout operation, extending battery life in portable systems.     The internal synchronous switch increases efficiency and eliminates the need for external Schottky diode. At shutdown mode, the input supply current is less than 1µA.   The FP6395 fault protection includes over current protection, short circuit protection, UVLO, input over voltage protection and thermal shutdown. The FP6395 is offered in TDFN-6(1.6mm×1.6mm) TDFN-6(2mm×2mm) Packages.       2.5V~6V Input Voltage Range 0.2V Reference Voltage 1.2A Output Current Low RDS(ON) for Internal Switch (Top/Bottom): 340mΩ/210mΩ 1.5MHz Switching Frequency Internal Compensation Function 1kHz ±10% PWM Dimming Control 100% Dropout Operation Input Over Voltage Protection Over Current Protection Over Temperature Protection with Auto Recovery RoHS Compliant and Halogen Free Applications    NB Camera 3AA or 4AA Batteries Powered Flashlight 1 Cell Li-Ion Battery Powered Flashlight Pin Assignments Ordering Information D2 Package TDFN-6 (1.6mmx1.6mm) FP6395□ TOP VIEW NC 1 EN 2 Package Type D2: TDFN-6 (1.6mmx1.6mm) 6 FB GND 5 LX 4 GND VIN 3 D7 Package TDFN-6 (2mmx2mm) TOP VIEW NC 1 EN 2 D7: TDFN-6 (2mmx2mm) TDFN-6 Marking Part Number Product Code FP6395D2 A FP6395D7 FZ2 6 FB GND VIN 3 5 GND 4 LX Figure 1. Pin Assignment of FP6395 FP6395-Preliminary 0.3-OCT-2018 1 FP6395 Typical Application Circuit OFF ON EN L1 VIN VIN C1 LX VOUT FP6395 C4 LED NC C2 FB GND R1 Figure 2. Schematic Diagram VIN=5V, the recommended BOM list is as below. C1 4.7μF MLCC C4 0.1μF MLCC L1 2.2μH C2 10μF MLCC Table 1. Recommended Component Values FP6395-Preliminary 0.3-OCT-2018 2 FP6395 Functional Pin Description Pin Name D2 Package Pin No. D7 Package Pin No. NC 1 1 No Connection. EN 2 2 Enable control pin. Pull high to turn the IC on, and pull low to disable the IC. Don’t leave this pin floating. VIN 3 3 Power supply input pin. Placed input capacitors as close as possible from VIN to GND to avoid noise influence. GND 4 5 Ground pin. Connect GND to exposed pad. LX 5 4 Power switching node. Connect an external inductor to this switching node. FB 6 6 Voltage feedback input pin. Connect FB and VOUT with a resistive voltage divider. This IC senses feedback voltage via FB and regulates it at 0.2V. Pin Function Block Diagram EN VIN 2M Enable Control VIN OVP UVLO Slope Compensation FB COMP EA Control Logic Driver Logic 1 X LX VREF OSC OTP COMP GND Figure 3. Block Diagram of FP6395 FP6395-Preliminary 0.3-OCT-2018 3 FP6395 Absolute Maximum Ratings (Note 1) ● VIN to GND ------------------------------------------------------------------------------------------------- -0.3V to +6.5V ● LX to GND --------------------------------------------------------------------------------------------------- -0.3V to (VIN +0.3V) ● EN, FB to GND --------------------------------------------------------------------------------------------- -0.3V to VIN ● Package Thermal Resistance, (θJA) (Note 2) TDFN-6 (1.6mm×1.6mm) ------------------------------------------------------------------ 160°C/W TDFN-6 (2mm×2mm) ------------------------------------------------------------------------ 136°C/W ● Package Thermal Resistance, (θJC) (Note 2) TDFN-6 (1.6mm×1.6mm) ------------------------------------------------------------------ 62°C/W TDFN-6 (2mm×2mm) ------------------------------------------------------------------------ 56°C/W ● Maximum Junction Temperature (TJ) ----------------------------------------------------------------- +150°C ● Lead Temperature (Soldering, 10sec.) --------------------------------------------------------------- +260°C ● Storage Temperature (TS) ------------------------------------------------------------------------------- -65°C to +150°C Note 1: Stresses beyond this listed under “Absolute Maximum Ratings" may cause permanent damage to the device. Note 2: θJA is measured at 25°C ambient with the component mounted on a high effective thermal conductivity 4 -layer board of JEDEC-51-7. θJC is measured at the exposed pad. The thermal resistance greatly varies with layout, copper thickness, number of layers and PCB size. Recommended Operating Conditions ● Supply Voltage (VIN) ------------------------------------------------------------------------------------------- +2.5V to +6V ● Operation Temperature Range (TOPR) -------------------------------------------------------------------- -40°C to +85°C FP6395-Preliminary 0.3-OCT-2018 4 FP6395 Electrical Characteristics (VIN=5V, VOUT=2.5V, TA=25°C, unless otherwise specified.) Parameter Symbol Input Supply Voltage Conditions VIN Input Over Voltage Protection Min 2.5 VIN OVP Shutdown Current ISHDN Quiescent Current Iq Reference Voltage VREF FB Input Leakage Current IFB Typ Max Unit 6.0 V 6.3 V EN=0V 0.1 1 μA VFB=0.65V, IOUT=0A 30 50 μA 0.2 0.206 V 0.01 1 µA 0.194 VFB=VIN P-Channel MOSFET On-Resistance (Note 3) RDS(ON) 340 mΩ N-Channel MOSFET On-Resistance (Note 3) RDS(ON) 210 mΩ ILIM 1.5 A P-Channel Current Limit (Note 3) EN High-Level Input Voltage VEN(H) EN Low-Level Input Voltage VEN(L) EN Input Current 1.5 V 0.4 V IEN 2.5 µA UVLO 2.4 V UVLO Hysteresis VHYS 0.3 V Oscillation Frequency FOSC Under Voltage Lockout Voltage IOUT=200mA 1.2 Minimum On Time 50 Maximum Duty Cycle 100 LX Discharge Resistance Thermal Shutdown Temperature 1.5 (Note 3) TSD 1.8 MHz ns % 100 Ω 150 °C Note 3: Guarantee by design. FP6395-Preliminary 0.3-OCT-2018 5 FP6395 Function Description The FP6395 is a high efficiency, internal compensation and constant frequency current mode step-down synchronous LED driver. It has integrated high-side (340mΩ, typ.) and low-side (210mΩ, typ.) power switches, and provides 1.2A continuous load current. It regulates input voltage from 2.5V to 6V, and down to an output voltage as low as 0.2V. Enable The FP6395 EN pin provides digital control to turn on/off the regulator. When the voltage of EN exceeds the threshold voltage, the regulator will start the soft start function. If the EN pin voltage is below the shutdown threshold voltage, the regulator will turn into the shutdown mode and the shutdown current will be smaller than 1μA. For auto start-up operation, connect EN to VIN. Under Voltage Lockout When the FP6395 is power on, the internal circuits will be held inactive until VIN voltage exceeds the UVLO threshold voltage. And the regulator will be disabled when VIN is below the UVLO threshold voltage. The hysteretic of the UVLO comparator is 200mV (typ). Input Over Voltage Protection The FP6395 supports input over voltage protection. When input voltage exceeds the input over Voltage threshold, the regulator will be shutdown unless the input over voltage is removed. FP6395-Preliminary 0.3-OCT-2018 Over Current Protection The FP6395 over current protection function is implemented by using cycle-by-cycle current limit architecture. The inductor current is monitored by measuring the high-side MOSFET series sense resistor voltage. When the load current increases, the inductor current will also increase. When the peak inductor current reaches the current limit threshold, the output voltage will start to drop. When the over current condition is removed, the output voltage will return to the regulated value. Short Circuit Protection The FP6395 provides short circuit protection function to prevent the device damaged from short condition. When the short condition occurs and the feedback voltage drops lower than 40% of the regulation level, the oscillator frequency will be reduced to prevent the inductor current increasing beyond the current limit. In the meantime, the current limit will also be reduced to lower the short current. Once the short condition is removed, the frequency and current limit will return to normal. Over Temperature Protection The FP6395 incorporates an over temperature protection circuit to protect itself from overheating. When the junction temperature exceeds the thermal shutdown threshold temperature, the regulator will be shutdown. And the hysteretic of the over temperature protection is 30°C (typ). 6 FP6395 Application Information Setting LED Current Output Capacitor Selection The FB pin regulated voltage is 200mV. Thus the LED current is: The output capacitor is used to keep the DC output voltage and supply the load transient current. When operating in constant current mode, the output ripple is determined by four components: 2 R m L R PPL Input Capacitor Selection The use of the input capacitor is filtering the input voltage ripple and the MOSFETS switching spike voltage. Because the input current to the step-down converter is discontinuous, the input capacitor is required to supply the current to the converter to keep the DC input voltage. The capacitor voltage rating should be 1.25 to 1.5 times greater than the maximum input voltage. The input capacitor ripple current RMS value is calculated as: C (RM 1 T t R PPL C t R PPL ( R PPL L t R t t The following figures show the form of the ripple contributions. VRIPPLE(ESR)(t) + VRIPPLE(ESL) (t) (t) T Where D is the duty cycle of the power MOSFET. This function reaches the maximum value at D=0.5 and the equivalent RMS current is equal to IOUT/2. The following diagram is the graphical representation of above equation. + VRIPPLE(C) (t) (t) + VNOISE (t) (t) 0.6 1A ICIN(RMS) (A) 0.5 0.4 0.3 0.5A 0.2 0.1 0 10 20 30 40 50 60 70 80 90 D (%) = VRIPPLE(t) A low ESR capacitor is required to keep the noise minimum. Ceramic capacitors are better, but tantalum or low ESR electrolytic capacitors may also suffice. (t) FP6395-Preliminary 0.3-OCT-2018 7 FP6395 Application Information (Continued) R R PPL ( L T F C T 1 L R L R PPL (C That will lower ripple current and result in lower output ripple voltage. The Δ L is inductor peak-to-peak ripple current: L T F T L C2 L C 1 F C T 1 L T T Where FOSC is the switching frequency, L is the inductance value, VIN is the input voltage, ESR is the equivalent series resistance value of the output capacitor, ESL is the equivalent series inductance value of the output capacitor and the COUT is the output capacitor. Low ESR capacitors are preferred to use. Ceramic, tantalum or low ESR electrolytic capacitors can be used depending on the output ripple requirements. When using the ceramic capacitors, the ESL component is usually negligible. It is important to use the proper method to eliminate high frequency noise when measuring the output ripple. The figure shows how to locate the probe across the capacitor when measuring output ripple. Remove the scope probe plastic jacket in order to expose the ground at the tip of the probe. It gives a very short connection from the probe ground to the capacitor and eliminates noise. Probe Ground A good compromise value between size and efficiency is to set the peak-to-peak inductor ripple current Δ L equal to 30% of the maximum load current. But setting the peak-to-peak inductor ripple current Δ L between 20%~50% of the maximum load current is also acceptable. Then the inductance can be calculated with the following equation: L L . T(MA T F T C L To guarantee sufficient output current, peak inductor current must be lower than the FP6395 high-side MOSFET current limit. The peak inductor current is shown as below: P A Load Current R PPL ( T(MA L 2 IPEAK IOUT(MAX) ∆IL Time VOUT GND Ceramic Capacitor Inductor Selection The output inductor is used for storing energy and filtering output ripple current. But the trade-off condition often happens between maximum energy storage and the physical size of the inductor. The first consideration for selecting the output inductor is to make sure that the inductance is large enough to keep the converter in the continuous current mode. FP6395-Preliminary 0.3-OCT-2018 8 FP6395 Application Information (Continued) PCB Layout Recommendation The device’s performance and stability are dramatically affected by PCB layout. It is recommended to follow these general guidelines shown as below: 1. Place the input capacitors and output capacitors as close to the device as possible. The traces which connect to these capacitors should be as short and wide as possible to minimize parasitic inductance and resistance. 2. Place feedback resistors close to the FB pin. 3. Keep the sensitive signal (FB) away from the switching signal (LX). 4. Multi-layer PCB design is recommended. FP6395-Preliminary 0.3-OCT-2018 9 FP6395 Outline Information FP6395D2 TDFN- 6 1.6mm×1.6mm Package (Unit: mm) SYMBOLS UNIT A A1 A2 D E L b e D2 E2 DIMENSION IN MILLIMETER MIN MAX 0.70 0.00 0.18 1.55 1.55 0.18 0.18 0.45 0.95 0.55 0.80 0.05 0.25 1.65 1.65 0.30 0.30 0.55 1.05 0.65 Carrier dimensions Tape Size (W1) mm Pocket Pitch (P) mm 12 4 FP6395-Preliminary 0.3-OCT-2018 Reel Size (A) in mm Reel Width (W2) mm 7 180 8.4 Empty Cavity Length mm Units per Reel 400~1000 3,000 10 FP6395 Outline Information (Continued) FP6395D7 TDFN-6 2mm×2mm Package (Unit: mm) SYMBOLS UNIT A A1 A2 D E a b e D1 E1 DIMENSION IN MILLIMETER MIN MAX 0.70 0.00 0.19 1.95 1.95 0.20 0.25 0.60 1.15 0.55 0.80 0.05 0.22 2.05 2.05 0.40 0.35 0.70 1.65 1.05 Carrier Dimensions Life Support Policy Fitipower’s products are not authorized for use as critical components in life support devices or other medical systems . FP6395-Preliminary 0.3-OCT-2018 11