LX7176CLQ

LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Description Features The LX7176 is a 3A step-down regulator with integrated MOSFETs placed in a space saving QFN12 2mm x 2mm package for today’s mobile devices. It uses an ultra fast, constant frequency hysteretic control method and a high switching frequency to minimize external filter components while maintaining excellent regulation. The LX7176 has a fixed 0.6V reference, Power Good, and Enable pins. The LX7176 operates from 3.0V to 5.5V rails.  0-3A Step-down Regulator Cycle-by-cycle current limiting protects against overcurrent conditions. The LX7176 operates in hiccup mode to further enhance the robustness of the converter for heavy over-load or short-circuit faults and it automatically recovers once the fault clears.  Enable and Power Good Function Thermal protection shuts down the regulator under over-temperature conditions. Over voltage conditions will immediately shut off the output to protect against permanent damage.  Operational Input Supply Voltage Range: 3.0V-5.5V (short durations to 6.5V)  Integrated PMOS and NMOS  Hysteretic Control Offers Best Transient Response  PWM Switching at a Constant 1.65MHz  Input Under-voltage and Over-voltage Protection  Internal Soft-start  Cycle-by-Cycle Over Current Protection  Hiccup Mode Protects Against Short Circuit Faults  RoHS Compliant & Halogen Free Applications  High Performance HDD  LCD TV  Notebook/Netbook  Server and Workstations  Video Cards  PoE Powered Devices Smart Phone Figure 1: Typical Application Diagram with 0.9V VOUT Copyright © 2012 Rev. 1.1a 1/28/2014 Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 1 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Other Typical Application Diagram Figure 2. Typical Application with 1.8V VOUT Pin Configuration and Pinout •7176 YWWL • Pin 1 Indicator, YWWL = Year/Week/Lot Code RoHS / Pb-free Matte Tin Pin Finish Figure 3: Pinout Copyright © 2012 Rev. 1.1a 1/28/2014 Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 2 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Ordering Information Ambient Temperature Type Package Part Number 0°C to 85°C RoHS compliant, Pb-free QFN 2x2mm 12L LX7176CLQ LX7176CLQ-TR Packaging Type Bulk Tape and Reel Thermal Properties Thermal Resistance(θJA) QFN 2x2mm 12L Typ 30 Units °C/W Note: The Jx numbers assume no forced airflow. Junction Temperature is calculated using TJ = TA + (PD x JA). In particular, θJA is a function of the PCB construction. The stated number above is for a four-layer board in accordance with JESD-51 (JEDEC). Pin Description Pin Number Pin Designator Description Supply Voltage – A capacitor is needed to prevent voltage spikes from damaging the device. The capacitor return should be connected directly to the PGND pin. 1 PVIN 2, 11 SW 3, 12 PGND Power Ground – Power return. 4 AGND Analog Ground – Quiet ground for control circuits. 5 NC 6 OUT Output Voltage Sense Pin – This pin monitors the output voltage. 7 FB Feedback – This pin is connected to an external resistor divider to program the system output voltage. 8 EN Enable – The device is enabled when this pin is held high. 9 PG Power Good – Open Drain output that is pulled low when the FB is outside the “good”range, during soft start, or during a fault condition. 10 VIN Internal control circuit supply voltage. Internal connection to PVIN. Copyright © 2012 Rev. 1.1a 1/28/2014 Switch Output – This pin switches between PVIN and GND. Leave pin unconnected. Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 3 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Block Diagram Figure 4: Block Diagram Copyright © 2012 Rev. 1.1a 1/28/2014 Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 4 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Absolute Maximum Ratings Performance is not necessarily guaranteed over this entire range. These are maximum stress ratings only. Exceeding these ratings, even momentarily, can cause immediate damage, or negatively impact long-term operating reliability. Parameter VIN, PVIN, EN, PG, OUT, FB to GND SW to GND SW to GND (Shorter than 50ns) Maximum Junction Temperature Storage Temperature Peak Lead Soldering Temperature (40s, reflow) Min -0.3 -0.3 -2 -65 Max 7 7 7 150 150 260 Units V V V °C °C °C Operating Ratings Performance is generally guaranteed over this range as further detailed below under Electrical Characteristics. Parameter Input Voltage Output Voltage Output Current Ambient Temperature Min 3.0 0.6 0 0 Max 5.5 3.3 3 85 Units V V A °C Note: Corresponding Max Junction Temperature is 125°C Copyright © 2012 Rev. 1.1a 1/28/2014 Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 5 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Electrical Characteristics Unless otherwise specified, the following specifications apply over the operating ambient temperature of 0°C ≤ TA ≤ 85°C except where otherwise noted with the following test conditions: PVIN = 5V. T J = 25°C, unless otherwise specified. Symbol VIN IQ ISLEEP UVLO UVLOHYST Parameter No Load Input Current Input Current at Shutdown Under Voltage Rising Threshold UVLO Hysteresis OVPR Over Voltage Rising Threshold OVPF Over Voltage Falling Threshold VREF VREF TSS Reference Voltage VREF Slew Rate THICCUP Hiccup Time Conditions Min Typ ILOAD = 0, PWM, VFB=0.75V 600 EN = low 0.1 VIN rising PVIN falling PVIN rising. Will also trigger on DV/DT > 1V/µs PVIN falling Max Units µA 3 µA 2.8 V 0.2 V 6.21 V 5.5 5.85 V 0.594 0.6 2 FB = 0.2V, does not include soft start time 0.606 V mV/µs 1.2 ms 0.1 %/V -0.1 %/A µA FB Line Regulation¹ Load Regulation¹ FB Input Current VIN from 4.0V to 5.5V, ILOAD = 1.0A ILOAD = 0.5A to 2A 1 FBUVLO FB Under Voltage Threshold VOUT below this threshold will initiate a hiccup sequence. VOUT Output Discharge Resistance EN = low Copyright © 2012 Rev. 1.1a 1/28/2014 80% 80 200 Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 VREF 1400 Ω Page 6 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Symbol Parameter Conditions Min Typ Max Units SW RDSON_H RDSON_L OCP TSH TH f TOCP EN VIH VIL VH III PG VPG90 VPG110 VPGHY PGRDSON High Side On Resistance Low Side On Resistance Rated Output Current Current Limit Thermal Shutdown Threshold¹ Thermal Shutdown Hysteresis¹ PWM Switching Frequency OCP off time in CCM WRT rated current 1.2 IOUT = 5A Input High Input Low Hysteresis Input Current PGOOD VOUT Lower Threshold PGOOD VOUT Upper Threshold Hysteresis PGOOD Pull-down Resistance PGOOD Leakage Current 140 35 mΩ 21 mΩ 3 A 170 200 150 °C 20 °C 1.65 2 MHz 360 ns 0.1 0.01 V V V µA 1.1 0.4 VOUT rising, percentage of VREF VOUT falling, percentage of VREF Percentage of VREF % 1 90 % 110 % 5 % 100 300 Ω 0 1 µA ¹ These parameters are not tested, but guaranteed by design and characterization. Copyright © 2012 Rev. 1.1a 1/28/2014 Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 7 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Typical Performance Curves (Efficiency) Figure 5: LX7176 Efficiency with 0.9V, 1.8V and 3.3V Output Voltage Copyright © 2012 Rev. 1.1a 1/28/2014 Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 8 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Step Response(Load Current = 1A to 2.5A, Cout = 4*22μF) CH2: VOUT, CH4: Load Current Figure 6. VOUT = 0.9V, L = 2.2μH CH2: VOUT, CH4: Load Current Figure 7. VOUT = 1.8V, L = 4.9μH CH2: VOUT, CH3: SW, CH4: Load Current Figure 8.VOUT = 0.9V, L = 2.2μH CH2: VOUT, CH3: SW, CH4: Load Current Figure 9. VOUT = 1.8V, L = 4.9μH Copyright © 2012 Rev. 1.1a 1/28/2014 Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 9 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet CH2: VOUT, CH3: SW, CH4: Load Current Figure 10. VOUT = 0.9V, L = 2.2μH Copyright © 2012 Rev. 1.1a 1/28/2014 CH2: VOUT, CH3: SW, CH4: Load Current Figure 11. VOUT = 1.8V, L = 4.9μH Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 10 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Theory of Operation Basic Operation Over Current Protection The LX7176 compares the FB voltage to an internal reference, VREF. When FB is lower than VREF, the upper switch turns on and the lower switch turns LX7166 off. When FB is higher than VREF, the upper switch turns off and the lower switch turns on, VREF is fixed at 0.6V. An internal ramp keeps FB constant over a wide range of output capacitor values and parasitic components (i.e. ESR, ESL). In addition, a frequency control loop keeps the switching frequency constant during continuous conduction mode (CCM). The LX7176 protects against all types of short circuit conditions. Cycle by cycle over current protection turns off the upper switch when the current exceeds the OCP threshold. When this occurs, the upper switch is kept off for about 360ns before being allowed to turn on again. After startup, if FB drops below the FB under voltage threshold, a hiccup sequence will be initiated where both output switches are shut off for 1.2ms before initiating another soft start. This protects against a crowbar short circuit. The FB under voltage detection is not active during startup. Startup The LX7176 is enabled when EN is high and PVIN rises above the UVLO threshold. At start up, VREF ramps up from 0V to 0.6V. While VREF ramps; PGOOD (PG Pin) is held low. At the end of the ramp time, PG is allowed to go high after FB has reached the PGOOD rising threshold. Application Information Output Components Selection VOUT Inductor (L1) 0.9V 1.8V 3.3V 2.2μH 4.9μH 1.0μH Copyright © 2012 Rev. 1.1a 1/28/2014 Upper Feedback Resistor (R4) 100kΩ 200kΩ 453kΩ Lower Feedback Resistor (R5) 200kΩ 100kΩ 100kΩ Output Capacitor (C2 & C3) 4x22μF 4x22μF 4x22μF Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 11 LX7176 1.65MHz 3A Synchronous Buck Converter Production Datasheet Package Dimensions QFN 2x2mm 12L Package D2 D L 10 b 9 1 8 2 7 3 E e 6 4 5 Top View b A A3 Bottom View Side View Dim A A3 B D D2 E e L MILLIMETERS MIN MAX 0.80 1.00 0.20 REF 0.20 0.30 2.0 BSC 0.50 2.0 BSC 0.50 REF 0.30 0.45 INCHES MIN MAX 0.031 0.039 0.008 REF 0.008 0.012 0.078 BSC 0.020 0.078 BSC 0.020 REF 0.012 0.018 Note: 1. Dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm (.006”) on any side. Lead dimension shall not include solder coverage. 2. Dimensions are in millimeters, inches for reference only. PRODUCTION DATA – Information contained in this document is proprietary to Microsemi and is current as of publication date. This document may not be modified in any way without the express written consent of Microsemi. Product processing does not necessarily include testing of all parameters. Microsemi reserves the right to change the configuration and performance of the product and to discontinue product at any time. Copyright © 2012 Rev. 1.1a 1/28/2014 Microsemi Analog Mixed Signal Group One Enterprise Aliso Viejo, CA 92656 USA 1-800-713-4113, 1-949-380-6100, fax 1-949-215-4996 Page 12