lm27212 National Semiconductor Corporation, lm27212 Datasheet
lm27212
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lm27212 Summary of contents
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... Typical Application © 2006 National Semiconductor Corporation The LM27212 also has a soft start pin for the external adjustment of soft start speed. The LM27212 combined with the LM27222 series of MOS- FET drivers, provides a layout-friendly, thermally optimized and noise-immune power solution for the mobile platform ...
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... Connection Diagrams Top View 48-Lead TSSOP (MTD) Order Number LM27212MTD See NS Package Number MTD48 Ordering Information Order Number LM27212MTD LM27212MTDX LM27212SQ LM27212SQX www.national.com 20152001 Order Number LM27212SQ NS Package Number SQA48A Package Drawing MTD48 MTD48 1000 Units Tape and Reel SQA48A 1000 Units Tape and Reel ...
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Pin Descriptions (TSSOP) Pin 1, VID0: First and least significant bit to program the output voltage, as specified in VID Code table. Pin 2, VID1: 2nd bit to program the output voltage, as specified in VID Code table. Pin 3, ...
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Pin Descriptions (LLP) Pin 1, VID4: 5th bit to program the output voltage, as speci- fied in VID Code table. Pin 2, VID5: 6th and most significant bit to program the output voltage, as specified in VID Code table. Pin ...
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VID Code Table VID ...
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Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VDD XPOK SW1 VRON DE_EN# VOVP, VBOOT VID0 to VID5 STP_CPU#, SLP VSLP, VSTP, SENSE CMP1, CMP2, CMPREF ILIM1, ...
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Electrical Characteristics type apply over a junction temperature range of -5˚C to +110˚C. Unless otherwise specified, VDD = 5V, SGND = DGND = SRCK1 = 0V. (Note 5) (Continued) Symbol Parameter I Dynamic Output Swing Slew SS3 Rate Control Current ...
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... JA JA dissipation of more power. The Absolute Maximum power dissipation should be de-rated by 12.5mW per ˚C above 25˚C ambient. The LM27212 actively limits its junction temperature to about 150˚C. Note 3: For detailed information on soldering plastic small-outline packages, refer to the Packaging Databook available from National Semiconductor Corporation. ...
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Timing Diagram 9 20152004 www.national.com ...
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Block Diagram www.national.com 10 20152003 ...
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... That is how load line programming is achieved. In reality, the switching frequency is typically a few hundred kilohertz. The inductor currents therefore has a finite amount of ripple. The LM27212 sets the inductor ripple current by alternately forcing a hysteresis current (ih) through RH1 and RH2. The hysteresis current ih causes a hysteresis voltage across RH1 and RH2 ...
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... POWER SAVING MODE When both the DE_EN# and STP_CPU# pins are asserted and SLP is not toggling, the LM27212 will enter the Power Saving mode. In such a mode, Channel 1 will operate in Diode Emulator mode. Channel 2’s status depends on SLP. ...
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... In a current mode hysteretic controller such as the LM27212, current sharing is intrinsic. However, due to the low resistance value of the sense resistors (as low as 1mΩ), care should be exercised ...
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... In the equations, τ is the delay from error comparator trip point to the instant external power FETs start to switch. For the LM27212 and LM27222, that value is found to be 150ns typical. To determine the maximum switching frequency, first use the following equation to find the V ...
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... INPUT CAPACITOR SELECTION The fact that the two switching channels of the LM27212 are 180˚ out of phase will help reduce the RMS value of the ripple current seen by the input capacitors. That will help = 60˚ ...
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Design Considerations Example: soft start time is preferred to be 1ms to 3ms, initial Vcore is 1.37V, and Dynamic VID / Mode Change slew rate is preferred less than 5mV/µs. So, Double-checking the soft start time: To ...
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Design Considerations SETTING CURRENT LIMIT The current limit comparator compares the voltage pre- established across the current limit set resistor (R13 in Fig- ure 1) and the voltage across the current sense resistors. The current sourced by the ILIMREF pin ...
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Special PCB Layout Considerations www.national.com (Continued) FIGURE 2. PCB Layout Example 18 20152007 ...
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19 www.national.com ...
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... RESISTOR R11 RESISTOR R12 RESISTOR R13 RESISTOR R14 RESISTOR R15 WSL2512 RESISTOR, SENSE R16 RESISTOR R17 RESISTOR R18 RESISTOR U1 LM27212 CONTROLLER, HYSTERETIC U2 LM27222 DRIVER U3 LM27222 DRIVER www.national.com Bill of Materials Design 1 Type Size 1812 7.3X4.3X3.8 mm3 7.3X4.3X2.8 mm3 0805 0805 0805 0805 ...
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... R10 RESISTOR R11 RESISTOR R12 RESISTOR R13 RESISTOR R14 RESISTOR R15 WSL2512 RESISTOR, SENSE R16 RESISTOR R17 RESISTOR R18 RESISTOR U1 LM27212 CONTROLLER, HYSTERETIC U2 LM27222 DRIVER U3 LM27222 DRIVER Bill of Materials Design 2 Type Size 1812 7.3X4.3X2.8 mm3 0805 0805 0805 0805 0805 0805 ...
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... Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 48-Lead TSSOP Package Order Number LM27212MTD NS Package Number MTD48 48-Lead LLP Package Order Number LM27212SQ NS Package Number SQA48A 22 ...
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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 ...