LM25010 NSC | Alldatasheet
Document overview
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Technical content
Features
n Wide 6V to 42V Input Voltage Range n Valley Current Limiting At 1.25A n Programmable Switching Frequency Up To 1 MHz n Integrated N-Channel Buck Switch n Integrated High Voltage Bias Regulator n No Loop Compensation Required n Ultra-Fast Transient Response n Nearly Constant Operating Frequency With Line and Load Variations n Adjustable Output Voltage n 2.5V, ±2% Feedback Reference n Programmable Soft-Start n Thermal shutdown Typical Applications n Non-Isolated Telecommunications Regulator n Secondary Side Post Regulator n Power SUpply for Automotive Electronics Package n LLP-10 (4 mmx4m m ) n TSSOP-14EP n Both Packages Have Exposed Thermal Pad For Improved Heat Dissipation Basic Step-Down Regulator 20172743 February 2006 LM25010 42V, 1.0A Step-Down Switching Regulator © 2006 National Semiconductor Corporation DS201727 www.national.com
Ordering Information
LM25010SD LLP-10 (4x4) SDC10A −40˚C to + 125˚C 1000 Units on Tape and Reel LM25010SDX LLP-10 (4x4) SDC10A −40˚C to + 125˚C 4500 Units on Tape and Reel LM25010MH TSSOP-14EP MXA14A −40˚C to + 125˚C 94 Units in Rail LM25010MHX TSSOP-14EP MXA14A −40˚C to + 125˚C 2500 Units on Tape and Reel LM25010 www.national.com 2
Name Description Application InformationLLP-10 TSSOP-14 1 2 SW Switching Node Internally connected to the buck switch source. Connect to the inductor, free-wheeling diode, and bootstrap capacitor. 2 3 BST Boost pin for bootstrap capacitor Connect a capacitor from SW to the BST pin. The capacitor is charged from VCC via an internal diode during the buck switch off-time. 3 4 ISEN Current sense During the buck switch off-time, the inductor current flows through the internal sense resistor, and out of the ISEN pin to the free-wheeling diode. The current limit comparator keeps the buck switch off if the ISEN current exceeds 1.25A (typical). 4 5 SGND Current Sense Ground Re-circulating current flows into this pin to the current sense resistor. 5 6 RTN Circuit Ground Ground return for all internal circuitry other than the current sense resistor. 6 9 FB Voltage feedback input from the regulated output Input to both the regulation and over-voltage comparators. The FB pin regulation level is 2.5V. 7 10 SS Softstart An internal 11.5 µA current source charges the SS pin capacitor to 2.5V to soft-start the reference input of the regulation comparator. 8 11 RON/SD On-time control and shutdown An external resistor from VIN to the RON/SD pin sets the buck switch on-time. Grounding this pin shuts down the regulator. 9 12 VCC Output of the bias regulator The voltage at VCC is nominally equal to V IN for VIN < 8.9V, and regulated at 7V for V IN > 8.9V. Connect a 0.47 µF, or larger capacitor from VCC to ground, as close as possible to the pins. An external voltage can be applied to this pin to reduce internal dissipation if V IN is greater than 8.9V. MOSFET body diodes clamp VCC to VIN if V CC > VIN. 10 13 VIN Input supply voltage Nominal input range is 6V to 42V. Input bypass capacitors should be located as close as possible to the VIN pin and RTN pins. 1,7,8,14 NC No connection. No internal connection. Can be connected to ground plane to improve heat dissipation. EP Exposed Pad Exposed metal pad on the underside of the device. It is recommended to connect this pad to the PC board ground plane to aid in heat dissipation. LM25010 www.national.com3
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 -0.3V to 45V BST to RTN -0.3V to 59V SW to RTN (Steady State) -1.5V BST to VCC 45V BST to SW 14V VCC to RTN -0.3V to 14V SGND to RTN -0.3V to +0.3V SS to RTN -0.3V to 4V VIN to SW 45V All Other Inputs to RTN -0.3V to 7V ESD Rating (Note 2) Human Body Model 2kV Storage Temperature Range -65˚C to +150˚C Lead Temperature (Soldering 4 sec) (Note 4) 260˚C Operating Ratings(Note 1) VIN Voltage 6.0V to 42V Junction Temperature LM25010 −40˚C to + 125˚C Electrical Charateristics Specifications with standard type are for T J = 25˚C only; limits in boldface type ap- ply over the full Operating Junction Temperature (T J) range. Minimum and Maximum limits are guaranteed through test, de- sign, or statistical correlation. Typical values represent the most likely parametric norm at T J = 25˚C, and are provided for ref- erence purposes only. Unless otherwise stated the following conditions apply: V IN = 24V, RON = 200kΩ. See (Note 5). Symbol Parameter Conditions Min Typ Max Units VCC Regulator VCCReg V CC regulated output 6.6 7 7.4 Volts VIN -V CC ICC = 0 mA, F S ≤ 200 kHz, 6.0V ≤ VIN ≤ 8.5V 100 mV VCC Bypass Threshold V IN Increasing 8.9 V VCC Bypass Hysteresis V IN Decreasing 260 mV VCC output impedance (0 mA ≤ ICC ≤ 5 mA) VIN = 6.0V 55 Ω VIN = 8.0V 50 VIN = 24V 0.21 VCC current limit (Note 3) V IN = 24V, VCC =0 V 1 5 m A UVLOVcc V CC under-voltage lock-out threshold VCC Increasing 5.25 V UVLOVCC hysteresis V CC Decreasing 180 mV UVLOVCC filter delay 100 mV overdrive 3 µs IIN operating current Non-switching, FB = 3V 645 920 µA IIN shutdown current RON/SD = 0V 90 170 µA Switch Characteristics RDS(on) Buck Switch RDS(on) ISW = 200mA 0.35 0.80 Ω UVLOGD Gate Drive UVLO V BST -V SW Increasing 1.7 3.0 4.0 V UVLOGD hysteresis 400 mV SOFT-START Pin ISS Internal current source 8.0 11.5 15 µA Current Limit ILIM Threshold Current out of I SEN 1 1.25 1.5 A Resistance from ISEN to SGND 130 m Ω Response time 150 ns On Timer, RON/SD Pin tON - 1 On-time V IN = 10V, RON = 200 kΩ 2.1 2.75 3.4 µs tON - 2 On-time V IN = 42V, RON = 200 kΩ 500 695 890 ns Shutdown threshold Voltage at RON/SD rising 0.30 0.7 1.05 V Threshold hysteresis 40 mV LM25010 www.national.com 4
Electrical CharateristicsSpecifications with standard type are for T J = 25˚C only; limits in boldface type apply over the full Operating Junction Temperature (T J) range. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at T J = 25˚C, and are provided for reference purposes only. Unless otherwise stated the following conditions apply: V IN = 24V, RON = 200kΩ. See (Note 5). (Continued) Symbol Parameter Conditions Min Typ Max Units Off Timer tOFF Minimum Off-time 260 ns Regulation and Over-Voltage Comparators (FB Pin) VREF FB regulation threshold 2.445 2.50 2.550 V FB over-voltage threshold 2.9 V FB bias current 1n A Thermal Shutdown T SD Thermal shutdown temperature 175 ˚C Thermal shutdown hysteresis 20 ˚C Thermal Resistance θ JA Junction to Ambient, 0 LFPM Air Flow ˚C/W θJC Junction to Case SDC Package 5.2 5.2 ˚C/W 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: The human body model is a 100pF capacitor discharged through a 1.5k Ω resistor into each pin. Note 3: VCC provides bias for the internal gate drive and control circuits. Device thermal limitations limit external loading. Note 4: For detailed information on soldering plastic TSSOP and LLP packages refer to the Packaging Data Book available from National Semiconductor Corporation. Note 5: Typical specifications represent the most likely parametric norm at 25˚C operation. LM25010 www.national.com5
Typical Performance Characteristics VCC vs VIN VCC vs ICC 20172704 20172705 ICC vs Externally Applied VCC On-Time vs VIN and RON 20172706 20172707 Voltage at RON/SD Pin I IN vs VIN 20172708 20172710 LM25010 www.national.com 6
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threshold, nominally set at 1.25A. under-voltage lock-out, and maximum duty cycle limit. FIGURE 1. Startup Sequence
tance may be required (R3 in the Block Diagram). where RL = the load resistance. with inherent current limiting at approximately 100 mA. shut off, regardless of the voltage at VIN. located as close as possible to the LM25010 pins. FIGURE 2. Self Biased Configuration
peak current out of the SW pin should not exceed 2A. ramic capacitor is recommended for C4. start-up, thereby reducing inrush currents. curs, or if the circuit is shutdown using the RON/SD pin. from standard value resistors in the range of 1.0 kΩ -1 0k Ω. A value of 1.0 k Ω will be used for R1 and for R2. FIGURE 4. Inductor Current - Current Limit Operation
frequency of 161 kHz at VIN = 6V, and 203 kHz at VIN = 40V. the above guideline will be used. mum inductor value, based on the manufacturer’s tolerance. ramic capacitor with a low ESR should be used for C1. FIGURE 5. Inductor Current
to be reduced, in some cases considerably, by reducing R3. is determined by C2’s ESR and the inductor ripple current. the minimum ripple current calculated using Equation 13. sipation and the junction temperature within the LM25010. See the next section for guidelines on this issue. possible to the C1/C2 ground line without going through vias. reduce the junction temperature. FIGURE 11. Low Output Ripple Using Ripple Injection
Physical Dimensions inches (millimeters) unless otherwise noted 14-Lead TSSOP Package 10-Lead LLP Package LM25010 www.national.com 16
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. For the most current product information visit us at www.national.com. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. BANNED SUBSTANCE COMPLIANCE National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. Leadfree products are RoHS compliant. National Semiconductor Americas Customer Support Center Email: new.feedback@nsc.com Tel: 1-800-272-9959 National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Support Center Email: ap.support@nsc.com National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: jpn.feedback@nsc.com Tel: 81-3-5639-7560 www.national.com LM25010 42V, 1.0A Step-Down Switching Regulator