LX1736

LX1736 TM ® VREF @ 800mV, 900mA, 1.0MHZ PWM P RODUCTION D ATA S HEET DESCRIPTION KEY FEATURES 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 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 The regulator is capable of providing an output load current of 900mA 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. 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 4V to 6V Efficiency @ VIN=5V, 4 VPWR N/C 6 95% 3.3uH 1.25V @ 875mA VO=1.25V (Lower) VO=3.3V (Upper) 85% 75% 65% 30uF 17.8K Ground Plane Tie-in 5 4.7uF VCC SW 3 10.0K 2 GND FB 1 55% 45% 35% 25% 1 10 100 OUTPUT CURRENT, mA 1000 Figure 1 – LX1736 Application Circuit and Typical Efficiency Performance PACKAGE ORDER INFO LX1736 LX1736 TA (°C) 0 to 125 LD Plastic MLPD 6 pin 3mm x 3mm LX1736CLD Package Marking RoHS Compliant / Pb-free Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1736CLD-TR) 1736 xxxx MSC Page 1 Copyright © 2005 Rev. 1.0, 1/3/2007 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 LX1736 TM ® VREF @ 800mV, 900mA, 1.0MHZ PWM P RODUCTION D ATA S HEET ABSOLUTE MAXIMUM RATINGS 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) 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. PACKAGE PIN OUT WWW . Microsemi . C OM FB GND 1 6 NC VCC VPWR 2 5 SW 3 4 LD PACKAGE (Top View) RoHS / Pb-free 100% matte Tin Lead Finish The thermal pad must be connected to ground THERMAL DATA LD Plastic MLP 3x3mm MO-229, 6-Pin 4°C/W 25 to 50°C/W THERMAL RESISTANCE-JUNCTION TO CASE, θJC 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 # VCC VPWR FB GND SW 5 4 1 2 3 Description Unregulated supply voltage input, ranging from +4V to 6.0V for internal analog control circuitry. Unregulated supply voltage input (+4V to 6.0V), high current path, supplies PMOSFET Drain of PWM switch. Feedback input for setting programming output voltage. Circuit ground for IC analog circuitry and high frequency gate drive bias, can be connected to heatsink terminal. Inductor and commutation diode connection point. Connects to internal PMOSFET Source of PWM Switch output. RECOMMENDED OPERATING CONDITIONS Parameter Input Operating Voltage Range Continuous Output Current Range Output Voltage Range Operating Junction Temperature Operating Ambient Temperature Symbol VIN IOUT VOUT TJ TA LX1736 Typ Unit V A V °C °C Min 4.5 0 0.8 0 0 Max 5.5 0.9 80%* VIN 125 85 DEVICE D DATA Copyright © 2005 Rev. 1.0, 1/3/2007 Microsemi Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 2 LX1736 TM ® VREF @ 800mV, 900mA, 1.0MHZ PWM P RODUCTION D ATA S HEET ELECTRICAL CHARACTERISTICS 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 Feedback Threshold Feedback Input Current PWM Frequency PFM Mode Transition Minimum DC Output Current Maximum DC Output Current Maximum Duty Cycle Closed Loop Load Regulation Efficiency Quiescent Current P-Channel Switch ON Resistance P-Channel Switch Current Limit P-Channel Switch Leakage Soft Start, VOUT Slew Rate Thermal Shutdown DC Average In-Rush Current at VCC and VPWR (summed) Output Voltage Overshoot (From either removal of a short circuit condition from VOUT or applied power during start up) Output Voltage Response to Dynamic Load Change Circuit Output Capacitance VFBT IFB-IN FOP-PWM IO-PFM IOUT IOUTMAX DMAX VOUT Load REG 4.0V < VIN < 6.0V VFB = VFBT + 10mV PWM Mode PFM mode 772 800 828 75 mV nA Khz mA mA 600 80 0 1500 VOUT≤ 1.4V VOUT > 2.9V ISW = IOUT max 10mA