LM5085SD/NOPB National Semiconductor, LM5085SD/NOPB Datasheet
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LM5085SD/NOPB
Specifications of LM5085SD/NOPB
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LM5085SD/NOPB Summary of contents
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... R of the PFET or an external sense resistor can be DS(ON) used to sense current for over-current detection. Typical Application, Basic Step Down Controller © 2009 National Semiconductor Corporation LM5085 Features ■ LM5085Q is an Automotive Grade product that is AEC- Q100 grade 1 qualified (-40°C to 125°C operating junction temperature) ■ ...
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Connection Diagrams Top View 8-Lead MSOP-EP Top View 8-Lead MSOP Ordering Information Order Number Package NSC Package Type LM5085QMYE MSOP-8EP LM5085QMY MSOP-8EP LM5085QMYX MSOP-8EP LM5085MYE MSOP-8EP LM5085MY MSOP-8EP LM5085MYX MSOP-8EP LM5085MME MSOP-8 LM5085MM MSOP-8 LM5085MMX MSOP-8 LM5085SDE LLP-8 LM5085SD LLP-8 ...
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Pin Descriptions Pin Name Description No. 1 ADJ Current Limit Adjust 2 RT On-time control and shutdown 3 FB Voltage Feedback from the regulated output 4 GND Circuit Ground 5 ISEN Current sense input for current limit detection. 6 PGATE ...
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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. VIN to GND ISEN to GND ADJ to GND RT GND Electrical Characteristics junction temperature (T ) range of -40°C to +125°C. Minimum and Maximum limits are guaranteed through test, design, or statistical J correlation ...
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... CC Note 4: For detailed information on soldering plastic MSOP and LLP packages refer to the Packaging Data Book available from National Semiconductor Corporation. Note 5: Tested layer JEDEC board. Four vias provided under the exposed pad. See JEDEC standards JESD51-5 and JESD51-7. ...
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Typical Performance Characteristics Unless otherwise specified the following conditions apply: T Efficiency (Circuit of Figure 4) Shutdown Current vs vs www.national.com = 25° 48V 30057705 IN 30057707 CC 30057709 6 Input Operating ...
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Off-Time vs. V and 30057712 ADJ Pin Current vs 30057717 Shutdown Current vs. Temperature 30057753 Voltage at the RT Pin Input Operating Current vs. Temperature VCC vs. Temperature 7 30057713 30057718 30057754 www.national.com ...
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On-Time vs. Temperature Off-Time vs. Temperature ADJ Pin Current vs. Temperature www.national.com Minimum On-Time vs. Temperature 30057755 Current Limit Comparator Offset vs. Temperature 30057757 PGATE Driver Output Resistance vs. Temperature 30057714 8 30057756 30057758 30057759 ...
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Feedback Reference Voltage vs. Temperature RT Pin Shutdown Threshold vs. Temperature Soft-Start Time vs. Temperature 30057715 30057760 9 30057716 www.national.com ...
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Block Diagram Sense resistor method shown for current limit detection. Minimum output ripple configuration shown. www.national.com 10 30057719 ...
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Functional Description OVERVIEW The LM5085 is a PFET buck (step-down) DC-DC controller using the constant on-time (COT) control principle. The input operating voltage range of the LM5085 is 4.5V to 75V. The use of a PFET in a buck regulator ...
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For V = 48V and t = 100 ns, the simplified equation is SHUTDOWN The LM5085 can be shutdown by grounding the RT pin (see Figure 1). In this mode the PFET is held off, and the VCC ...
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For t in Equation 11 use the minimum on-time at the SW ON node. To determine this time period add the “Minimum on- time in current limit” specified in the Electrical Characteristics (t -4) to the difference of the turn-off ...
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PFET with a smaller Total Gate Charge must be used. SOFT-START The internal soft-start feature of the LM5085 allows the reg- ulator to gradually reach a steady state operating point at power up, thereby reducing ...
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ADJ pin current (32 µA), the required R resistor calculates to: ADJ A standard value 2.1 kΩ resistor is selected. The nominal current limit threshold calculates to: Using the tolerances for the ADJ pin ...
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C : The capacitor at the VCC pin (from VIN to VCC) pro- VCC vides not only noise filtering and stability for the VCC regula- tor, but also provides the surge current for the PFET gate drive. The typical recommended ...
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FIGURE 5. Efficiency vs. Load Current and V (Circuit of Figure 4) FIGURE 6. Frequency vs (Circuit of Figure 4) 30057705 FIGURE 7. Current Limit vs 30057744 FIGURE 8. LM5085 Power Dissipation 17 30057745 IN (Circuit ...
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Alternate Output Ripple Configurations The minimum ripple configuration, employing C1, C2, and R3 in figure 4, results in a low ripple amplitude at V mined mainly by the characteristics of the output capacitor and the ripple current in L1. This ...
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PC Board Layout In most applications, the heat sink pad or tab con- nected to the switch node, i.e. the junction of Q1, L1 and D1. While it is common to extend the PC board pad from ...
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Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 8-Lead MSOP-EP Package NS Package Number MUY08A 8-Lead MSOP Package NS Package Number MUA08A 20 ...
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LLP Package NS Package Number SDA08A 21 www.national.com ...
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