LM2673S-12/NOPB National Semiconductor, LM2673S-12/NOPB Datasheet
LM2673S-12/NOPB
Specifications of LM2673S-12/NOPB
*LM2673S-12/NOPB
LM2673S-12
Related parts for LM2673S-12/NOPB
LM2673S-12/NOPB Summary of contents
Page 1
... The output voltage is guaranteed to a ±2% tolerance. The clock frequency is con- trolled to within a ±11% tolerance. Typical Application SIMPLE SWITCHER ® registered trademark of National Semiconductor Corporation © 2008 National Semiconductor Corporation ® 3A Step-Down Voltage Regulator with Features ■ ...
Page 2
... Connection Diagrams and Ordering Information TO-263 Package Top View Order Number LM2673S-3.3, LM2673S-5.0, LM2673S-12 or LM2673S-ADJ See NSC Package Number TS7B Ordering Information for LLP Package Output Voltage Order Information 12 LM2673SD-12 12 LM2673SDX-12 3.3 LM2673SD-3.3 3.3 LM2673SDX-3.3 5.0 LM2673SD-5.0 5.0 LM2673SDX-5.0 ADJ LM2673SD-ADJ ...
Page 3
... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Input Supply Voltage Softstart Pin Voltage Switch Voltage to Ground (Note 13) Boost Pin Voltage Feedback Pin Voltage Power Dissipation Electrical Characteristics of operation, −40°C to 125°C. Specifications appearing in normal type apply for T LM2673-3 ...
Page 4
All Output Voltage Versions Electrical Characteristics Limits appearing in bold type face apply over the entire junction temperature range of operation, −40°C to 125°C. Specifications appearing in normal type apply for T 5V and Adjustable versions and V IN Symbol ...
Page 5
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings indicate conditions under which of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated ...
Page 6
Typical Performance Characteristics Normalized Output Voltage Efficiency vs Input Voltage Switch Current Limit www.national.com 10091304 10091306 Operating Quiescent Current 10091308 6 Line Regulation 10091305 Efficiency vs I LOAD 10091307 10091309 ...
Page 7
Switching Frequency Load Transient Response for Continuous Mode V = 20V OUT μ 200 μF, C OUT OUT A: Output Voltage, 100 mV//div, AC-Coupled. B: Load Current: 500 ...
Page 8
Continuous Mode Switching Waveforms V = 20V 5V OUT μ 200 μF, C OUT A: V Pin Voltage, 10 V/div Inductor Current, 1 A/div C: Output Ripple Voltage, 20 ...
Page 9
... LM267X Made Simple (version 2.0) a complete switching power supply can be de- signed quickly. The software is provided free of charge and can be downloaded from National Semiconductor's Internet site located at http://www.national.com. SWITCH OUTPUT This is the output of a power MOSFET switch connected di- rectly to the input voltage ...
Page 10
DESIGN CONSIDERATIONS FIGURE 1. Basic circuit for fixed output voltage applications. FIGURE 2. Basic circuit for adjustable output voltage applications Power supply design using the LM2673 is greatly simplified by using recommended external components. A wide range of inductors, capacitors ...
Page 11
Both surface mount and through-hole devices are available. The inductors from each of the three manufacturers have unique character- istics. Renco: ferrite stick core inductors; benefits are typically low- est cost and ...
Page 12
The peak switch current is equal to a factor of 37,125 divided resistance of 8.2KΩ sets the current limit to typi- ADJ cally 4.5A. For predictable control of the current limit it is recommended to keep ...
Page 13
... Step 1: Operating conditions are: max) and the 2.5A Vout = 14.8V in Vin max = 28V Iload max = 2A Step 2: Select an LM2673S-ADJ. To set the output voltage to 14.9V two resistors need to be chosen (R1 and R2 in Figure 2). For the adjustable device the output voltage is set by the following relationship: Where recommended value to use for ...
Page 14
Using Figure 6, the intersection of 27V•μS horizontally and the 2A vertical line (I max) indicates that L38 , a 68μH in- load ductor, should be used. From Table 1, L38 in a surface mount component is available from Pulse ...
Page 15
Inductor Selection Guides For Continuous Mode Operation FIGURE 3. LM2673-3.3 FIGURE 4. LM2673-5.0 10091319 10091320 15 10091321 FIGURE 5. LM2673-12 10091322 FIGURE 6. LM2673-ADJ www.national.com ...
Page 16
Inductor Inductance Current Reference (µH) Number L23 33 1.35 L24 22 1.65 L25 15 2.00 L29 100 1.41 L30 68 1.71 L31 47 2.06 L32 33 2.46 L33 22 3.02 L34 3.65 15 L38 68 2.97 L39 47 3.57 L40 ...
Page 17
Capacitor Selection Guides Capacitor AVX TPS Series Reference C (µF) WV (V) Code C1 330 C2 100 C3 220 100 C10 22 C11 C12 C13 Table 2. Input and ...
Page 18
Capacitor Sanyo OS-CON SA Series Reference C (µF) WV (V) Code C1 47 6.3 C2 150 6.3 C3 330 6.3 C4 100 10 C5 220 100 16 C8 150 16 C9 100 20 C10 47 ...
Page 19
Table 3. Output Capacitors for Fixed Output Voltage Application Output Inductance Voltage (V) (µ 3 100 Output Inductance Sanyo OS-CON SA Voltage (V) ...
Page 20
Table 4. Input Capacitors for Fixed Output Voltage Application (Assumes worst case maximum input voltage and load current for a given inductance value) Output Inductance Voltage (V) (µ 3 ...
Page 21
Table 5. Schottky Diode Selection Table Reverse Surface Mount Voltage More (V) 20V SK32 30V SK33 MBRD835L 30WQ03F 40V SK34 MBRB1545CT 30BQ040 6TQ045S 30WQ04F MBRS340 MBRD340 SK35 50V or More 30WQ05F Diode Manufacturer Contact Numbers Phone International ...
Page 22
Table 6. Output Capacitors for Adjustable Output Voltage Applications Output Voltage Inductance (V) 1.21 to 2.50 2.5 to 3.75 3. 6.25 6.25 to 7.5 7 12.5 12 ...
Page 23
Output Capacitors for Adjustable Output Voltage Applications (continued) Output Voltage Inductance Sanyo OS-CON SA (V) (µH) No. 33* 2 1.21 to 2.50 47* 2 33* 1 2.5 to 3. ...
Page 24
... Physical Dimensions www.national.com inches (millimeters) unless otherwise noted TO-263 Surface Mount Power Package Order Number LM2673S-3.3, LM2673S-5.0, LM2673S-12 or LM2673S-ADJ NS Package Number TS7B 24 ...
Page 25
TO-220 Power Package Order Number LM2673T-3.3, LM2673T-5.0, LM2673T-12 or LM2673T-ADJ NS Package Number TA07B 14-Lead LLP Package NS Package Number SRC14A 25 www.national.com ...
Page 26
... For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock Conditioners www.national.com/timing Data Converters www.national.com/adc Displays www.national.com/displays Ethernet www.national.com/ethernet Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www ...