LX1736 ® TM 5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR P RODUCTION D ATA S HEET KEY FEATURES DESCRIPTION Few External Components 800mv Internal Reference Tight Regulation over Line, Load and Temperature 4.5V to 5.5V Input Range Internal Soft Start Controls Inrush Current High Efficiency Low Quiescent Current, 600μA Fully Fault Protected Thin MO-229, 6-Pin Package The regulator is capable of providing an output load current up to 1.25A and has no minimum load current requirement for stable operation. Current limit senses on a cycle-by cycle basis to protect the switch. Power conversion efficiency is maximized with PFM mode of operation and low regulator quiescent current. The LX1736 operational supply voltage range covers 4.0V to 6.0V, features include: power on delay; soft start to limit inrush currents and thermal shutdown during fault conditions. The 6-pin JEDEC MO-229 package provides a small form factor and low profile at 3x3x1mm with excellent power dissipation capability on surface mount PCB’s. WWW . Microsemi .C OM The LX1736 operates as a Current Mode PWM Buck regulator that switches to PFM mode under light loads. The entire regulator function is implemented with only a few, lowcost external components. The LX1736 responds quickly to dynamic load changes using a high bandwidth error amplifier and internal compensation. Tight output voltage regulation is maintained with the temperature compensated 800mV, bandgap reference achieving +/-3.5% regulation tolerance for all line, load and thermal conditions. The output voltage is easily programmed, from 800mV to 90% of VIN with two external resistors APPLICATIONS Point of Load Regulation DSP, ASIC and Core Voltage Supplies Hard Disk Drives Set Top Boxes RoHS compliant product IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com PRODUCT HIGHLIGHT Efficiency @ VIN=5V, VO=1.25V (Lower) VO=3.3V (Upper) 95% 85% 75% 65% 55% 45% 35% 25% 1 1000 LX1736 Figure 1 – LX1736 Application Circuit and Typical Efficiency Performance 10 100 OUTPUT CURRENT, mA PACKAGE ORDER INFO TA (°C) LD Plastic MLPD 6 pin 3mm x 3mm RoHS Compliant / Pb-free 0 to 125 LX1736CLD Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1736CLD-TR) Copyright © 2007 Rev. 1.1., 11/25/2008 Package Marking 3049 xxxx MSC Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 1 LX1736 ® TM 5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR P RODUCTION D ATA S HEET ABSOLUTE MAXIMUM RATINGS PACKAGE PIN OUT Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of specified terminal. 1 6 2 5 3 4 NC FB GND VCC SW VPWR LD PACKAGE (Top View) RoHS / Pb-free 100% matte Tin Pin Finish WWW . Microsemi .C OM Input Voltage (VCC or VPWR) ..................................................................... -0.3V to 7.0V SW to GND........................................................................................ -0.3V to (VIN + 0.3V) VFB to GND................................................................................................... -0.3V to +2V SW Peak Current .....................................................................................Internally Limited Junction Operating Temperature Range........................................................0°C to +125°C Storage Temperature Range, TA..................................................................-65°C to 150°C Maximum Junction Temperature ............................................................................... 150°C Package Peak Temp. for Solder Reflow (40 seconds max. exposure)........... 260°C (+0, -5) THERMAL DATA LD Plastic MLP 3x3mm MO-229, 6-Pin THERMAL RESISTANCE-JUNCTION TO CASE, θJC 4°C/W 25 to 50°C/W THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA Junction Temperature Calculation: TJ = TA + (PD x θJA). The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow. FUNCTIONAL PIN DESCRIPTION Name Pin # Description VCC 5 Unregulated supply voltage input, ranging from +4V to 6.0V for internal analog control circuitry. VPWR 4 Unregulated supply voltage input (+4V to 6.0V), high current path, supplies PMOSFET Drain of PWM switch. FB 1 Feedback input for setting programming output voltage. GND 2 Circuit ground for IC analog circuitry and high frequency gate drive bias, exposed pad area on bottom of package may be connected to ground or left floating. SW 3 Inductor and commutation diode connection point. Connects to internal PMOSFET Source of PWM Switch output. RECOMMENDED OPERATING CONDITIONS Parameter Symbol Min LX1736 Typ Max Unit ` Input Operating Voltage Range 4.5 5.5 V Continuous Output Current Range IOUT 0 0.9 A Output Voltage Range VOUT 0.8 80% of VIN V TJ 0 125 °C Operating Junction Temperature DEVICE VIN DATA Copyright © 2007 Rev. 1.1., 11/25/2008 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 2 LX1736 ® TM 5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR P RODUCTION D ATA S HEET ELECTRICAL CHARACTERISTICS Feedback Threshold VFBT 4.0V < VIN < 6.0V Feedback Input Current IFB-IN VFB = VFBT + 10mV PWM Frequency FOP-PWM PWM Mode PFM Mode Transition IO-PFM PFM mode Minimum DC Output Current Maximum DC Output Current Maximum Duty Cycle Closed Loop Load Regulation DMAX VOUT Load REG Efficiency η Quiescent Current IQ ISW = IOUT max 10mA<IOUT<IOUT MAX 1450 Khz 80 mA mA 1.25 or 0.7/duty cycle whichever is less 80 A % -0.5 0.5 %VOUT 70 % VFB = VFBT + 10mV Peak Current at Switch Pin (Not DC Current) TJ ≤ 70˚C TSD nA VIN=5V, VOUT>1.1V, IOUT≥ 150mA ISW CL Thermal Shutdown 75 % P-Channel Switch Current Limit VO-SR mV 55 ISW = 0.9A Soft Start, VOUT Slew Rate 828 VIN=5V, VOUT≥1.1V, IOUT= 10mA RDS(ON) ISW LKG 800 TJ ≤ 70˚C P-Channel Switch ON Resistance P-Channel Switch Leakage 800 0 IOUT IOUTMAX 772 600 900 0.375 μA Ω 1.1 A 1.4 VFB = VFBT + 10mV Initial Power On or After a Short Circuit, COUT = 20µF (Silicon Temperature) 21 135 5 μA 50 V/ms 150 °C IINRUSH VIN ramping from 0V to 5V having a slew rate of 0.1V/S min to 0.5V/uS max and COUT = 20µF 550 mA Output Voltage Overshoot (From either removal of a short circuit condition from VOUT or applied power during start up) VO OS Applied power VIN ramp rate of 0.1V/S min to 0.5V/uS max 5 % Output Voltage Response to Dynamic Load Change VO OS Output load current change from 100ma to 700ma or 700ma to 100ma, transition time <100ns -5 5 % Circuit Output Capacitance COUT Closed Loop stability 20 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 ELECTRICALS DC Average In-Rush Current at VCC and VPWR (summed) Copyright © 2007 Rev. 1.1., 11/25/2008 WWW . Microsemi .C OM Specifications are guaranteed over the junction temperature range of: 0°C < T < 125°C for VIN = 4.5V to 5.5V (unless noted otherwise), not all of these parameters are production tested but are assured by design, characterization and correlation with statistical process controls.. Typical values are at TA=23°C. LX1736 Parameter Symbol Test Conditions Units Min Typ Max μF Page 3 LX1736 5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR ® TM P RODUCTION D ATA S HEET WWW . Microsemi .C OM APPLICATION SUPPORT Vout Cout INDUCTOR DIODE Cout Cout LX1736 Vpwr Sw Cin Vin Gnd n/c FB Cout Rf Vin Rf Ground PCB Layout Considerations 1- Maintain separate traces leading from the decoupling capacitor, CIN, to the supply input pins of the IC for VCC and VPWR. This ensures that the noise and voltage drops associated with the high dI/dt pulses from the PWM switching are minimized for the internal control circuitry of the IC. Diode ground should return to COUT ground with minimum physical distance before joining the IC Ground connection. 23- Feed back resistor return path to ground should be located closely to the IC Pin 2 to avoid VOUT offsets induced by ground drops and noise. APPLICATION Copyright © 2007 Rev. 1.1., 11/25/2008 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 4 LX1736 5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR ® TM P RODUCTION D ATA S HEET SIMPLIFIED BLOCK DIAGRAM WWW . Microsemi .C OM VPWR VCC UVLO Bias CL Clock And Ramp PWM S R SW 920mV REF EA OVP BG REF 800mV LX1736 GND FB APPLICATION PERFORMANCE Dynamic Load Change Response CH1 = Vout AC Coupled CH2 = Load Switch CH4 = Output Current, 100mA to 750mA VIN=5V, L=3.3uH, COUT = 20uF APPLICATION Copyright © 2007 Rev. 1.1., 11/25/2008 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 5 LX1736 TM ® 5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR P RODUCTION D ATA S HEET WWW . Microsemi .C OM Start-up Inrush Current Control CH1 = SW Pin CH2 = Vout @ 3.32V CH4 = Input Current VIN=5V, No Output load, COUT = 20uF VOUT Response to Short Circuit Removal CH1 = Vout programmed at 1.2V CH2 = Short CKT Duration CH4 = Output Current COUT = 20uF APPLICATION Copyright © 2007 Rev. 1.1., 11/25/2008 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 6 LX1736 5V 1.25A 1.0MHz PWM/PFM STEP DOWN REGULATOR ® TM P RODUCTION D ATA S HEET PACKAGE DIMENSIONS WWW . Microsemi .C OM LD MO-229 6-Pin Plastic 3 x 3 x .9 mm D L1 D2 Pin 1 ID E E2 L b A1 e K A Dim A A1 K e L b D2 E2 D E L1 MILLIMETERS MIN MAX 0.80 1.00 0.00 0.05 0.20 MIN 0.95 BSC 0.30 0.50 0.30 0.45 1.90 2.40 1.15 1.65 3.00 BSC 3.00 BSC 0.00 0.15 INCHES MIN MAX 0.031 0.039 0.000 0.002 0.008 MIN 0.037 BSC 0.012 0.020 0.012 0.018 0.075 0.094 0.045 0.065 0.118 BSC 0.118 BSC 0.000 0.006 Note: 1. 2. 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. Exposed heatsink pad on bottom may be left floating or connected to ground. NOTES MECHANICAL 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 © 2007 Rev. 1.1., 11/25/2008 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 7