100V Step-Down Switching Regulator

LM5009 150 mA, 100V Step-Down Switching Regulator February 2006 LM5009 150 mA, 100V Step-Down Switching Regulator General Description The LM5009 Step Down Switching Regulator features all of the functions needed to implement a low cost, efficient, Buck bias regulator. This device is capable of driving a 150 mA load current from a 9.5V to 95V input source. The switching frequency can exceed 600 kHz, depending on the input and output voltages. The output voltage may be set from 2.5V to 85V. This high voltage regulator contains an N-Channel buck switch and internal startup regulator. The device is easy to implement and is provided in the MSOP-8 and the thermally enhanced LLP-8 packages. The LM5009 is a well suited alternative to a high voltage monolithic or discrete linear solution where the power loss becomes unacceptable. The regulator’s operation is based on a hysteretic control scheme using an ON time inversely proportional to VIN. This feature allows the operating frequency to remain relatively constant over load and input voltage variations. The hysteretic control requires no loop compensation, resulting in an ultra-fast transient response. An intelligent current limit is implemented with forced OFF time, which is inversely proportional to Vout. This scheme ensures short circuit protection while providing minimum foldback. Other features include: Thermal Shutdown, Vcc under-voltage lockout, Gate drive under-voltage lockout, and Maximum Duty Cycle limiter. Features n n n n n n n n n n n n n Integrated N-Channel MOSFET Guaranteed 150 mA output current capability Ultra-Fast Transient Response No loop compensation required Vin feed forward provides constant operating frequency Switching frequency can exceed 600 kHz Highly efficient operation 2% accurate 2.5V feedback from -40˚C to 125˚C Internal startup regulator Intelligent current limit protection External shutdown control Thermal shutdown MSOP-8 and thermally enhanced LLP packages Typical Applications n Heat sink eliminator for classic linear regulator applications n 12V, 24V, 36V, and 48V rectified AC systems n 42V Automotive n Non-isolated AC mains charge coupled supplies n LED Current Source Package n MSOP - 8 n LLP - 8 (4mm x 4mm) (Available Soon) Typical Application Circuit 20165828 Basic Stepdown Regulator © 2006 National Semiconductor Corporation DS201658 www.national.com LM5009 Connection Diagram 20165802 8-Lead MSOP, LLP Ordering Information Order Number LM5009MM LM5009MMX LM5009SD LM5009SDX Package Type MSOP-8 MSOP-8 LLP-8 LLP-8 NSC Package Drawing MUA08A MUA08A Supplied As 1000 Units on Tape and Reel 3500 Units per Reel Available Soon Available Soon www.national.com 2 LM5009 Pin Descriptions Pin 1 2 Name SW BST Switching output Boost Pin Description Application Information Power switching output. Connect to the inductor, re-circulating diode, and bootstrap capacitor. An external capacitor is required between the BST and the SW pins. A 0.01µF ceramic capacitor is recommended. An internal diode charges the capacitor from VCC. A resistor between this pin and RTN sets the off-time when current limit is detected. The off-time is preset to 35µs if FB = 0V. Ground for the entire circuit. This pin is connected to the inverting input of the internal regulation comparator. The regulation threshold is 2.5V. A resistor between this pin and VIN sets the switch on-time as a function of VIN. The minimum recommended on-time is 250ns at the maximum input voltage. This pin can be used for remote shutdown. If an auxiliary voltage is available to raise the voltage on this pin above the regulation setpoint (7V), the internal series pass regulator will shutdown, reducing the IC power dissipation. Do not exceed 14V. This voltage provides gate drive power for the internal Buck switch. An internal diode is provided between this pin and the BST pin. A local 0.1µF decoupling capacitor is required. Recommended operating range: 9.5V to 95V. Exposed metal pad on the underside of the device. It is recommended to connect this to the PC board ground plane to aid in heat dissipation. 3 RCL Current Limit off-time set pin 4 5 RTN FB Ground pin Feedback input from Regulated Output 6 RON/SD On-time set pin 7 VCC Output from the internal high voltage startup regulator. Regulated at 7.0V. 8 VIN EP Input voltage Exposed Pad (LLP Package only) 3 www.national.com LM5009 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN to RTN BST to RTN SW to RTN (Steady State) ESD Rating (Note 5) Human Body Model BST to VCC 2kV 100V -0.3V to 100V -0.3V to 114V -1V BST to SW VCC to RTN All Other Inputs to RTN Storage Temperature Range 14V 14V -0.3 to 7V -65˚C to +150˚C Operating Ratings (Note 1) VIN Operating Junction Temperature 9.5V to 95V −40˚C to + 125˚C Electrical Characteristics Limits in standard type are for TJ = 25˚C only, and limits in boldface type apply over the junction temperature (TJ) range of -40˚C to +125˚C. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25˚C, and are provided for reference purposes only. Unless otherwise stated, the following conditions apply: VIN = 48V, RON = 200kΩ. See (Note 3) Symbol VCC Supply VCC Reg VCC Regulator Output VCC Current Limit VCC undervoltage Lockout Voltage (VCC increasing) VCC Undervoltage Hysteresis VCC UVLO Delay (filter) IIN Operating Current IIN Shutdown Current Switch Characteristics Buck Switch Rds(on) Gate Drive UVLO Gate Drive UVLO Hysteresis Current Limit Current Limit Threshold Current Limit Response Time OFF time generator (test 1) OFF time generator (test 2) On Time Generator TON - 1 TON - 2 Remote Shutdown Threshold Remote Shutdown Hysteresis Vin = 10V Ron = 200K Vin = 95V Ron = 200K Rising 2.15 200 0.40 2.77 300 0.70 35 3.5 420 1.05 µs ns V mV Iswitch Overdrive = 0.1A Time to Switch Off FB=0V, RCL = 100K FB=2.3V, RCL = 100K 0.25 0.31 400 35 2.56 0.37 A ns µs µs ITEST = 200mA, (Note 6) VBST − VSW Rising 3.4 2.0 4.5 430 4.4 5.5 Ω V mV 100mV overdrive Non-Switching, FB = 3V RON/SD = 0V (Note 4) 6.6 7 9.5 6.3 200 10 485 76 675 150 7.4 V mA V mV µs µA µA Parameter Conditions Min Typ Max Units www.national.com 4 LM5009 Electrical Characteristics (Continued) Limits in standard type are for TJ = 25˚C only, and limits in boldface type apply over the junction temperature (TJ) range of -40˚C to +125˚C. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25˚C, and are provided for reference purposes only. Unless otherwise stated, the following conditions apply: VIN = 48V, RON = 200kΩ. See (Note 3) Symbol Parameter Minimum Off Timer Conditions FB = 0V Internal reference Trip point for switch ON Trip point for switch OFF 2.445 Min Typ 300 2.5 2.875 1 165 25 MUA Package SDC Package 200 2.550 Max Units ns V V nA ˚C ˚C ˚C/W ˚C/W Minimum Off Time Regulation and OV Comparators FB Reference Threshold FB Over-Voltage Threshold FB Bias Current Thermal Shutdown Tsd Thermal Shutdown Temp. Thermal Shutdown Hysteresis Thermal Resistance θJA Junction to Ambient Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics. Note 2: For detailed information on soldering plastic MSOP and LLP packages, refer to the Packaging Data Book available from National Semiconductor Corporation. Note 3: All limits are guaranteed. All electrical characteristics having room temperature limits are tested during production with TA = TJ = 25˚C. All hot and cold limits are guaranteed by correlating the electrical characteristics to process and temperature variations and applying statistical process control. Note 4: The VCC output is intended as a self bias for the internal gate drive power and control circuits. Device thermal limitations limit external loading. Note 5: The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. All pins are rated for 2 kV, except VIN and VCC which are rated for 1 kV. Note 6: For devices procured in the LLP-8 package the Rds(on) limits are guaranteed by design characterization data only. 5 www.national.com LM5009 Typical Performance Characteristics On-Time vs VIN and RON VCC vs VIN and FS 20165809 20165829 Current Limit Off-Time vs VFB and RCL VCC vs ICC and VIN 20165812 20165830 ICC Current vs Applied VCC Voltage 20165811 www.national.com 6 LM5009 Typical Application Circuit and Block Diagram 20165801 FIGURE 1. Functional Description The LM5009 Step Down Switching Regulator features all the functions needed to implement a low cost, efficient, Buck bias power converter. This high voltage regulator contains a 100 V N-Channel Buck Switch, is easy to implement and is provided in the MSOP-8 and the thermally enhanced LLP-8 packages. The regulator is based on a hysteretic control scheme using an on-time inversely proportional to VIN. The hysteretic control requires no loop compensation. Current limit is implemented with forced off-time, which is inversely proportional to VOUT. This scheme ensures short circuit protection while providing minimum foldback. The Functional Block Diagram of the LM5009 is shown in Figure 1. The LM5009 can be applied in numerous applications to efficiently regulate down higher voltages. This regulator is well suited for 48 Volt Telecom and the 42V Automotive power bus ranges. Additional features include: Thermal Shutdown, VCC under-voltage lockout, Gate drive undervoltage lockout, Max Duty Cycle limit timer and the intellig