Texas Instruments AN-1975 LMP8640 User Manual Download Page 8

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Summary of Contents for AN-1975 LMP8640

Page 1: ...flows in the shunt resistor from the LOAD pin to the IN pin The device U2 is able to sense the current when it flows in the shunt resistor from IN pin to LOAD pin Table 2 Output signals OUT Output of device U2 the voltage at this pin is related to the current that flows from the IN pin to the LOAD pin OUT Output of device U1 the voltage at this pin is related to the current that flows from the LOA...

Page 2: ...ltages are listed in Table 3 Table 3 Max Common Mode Voltage DEVICE MAX VCM LMP8640 42V LMP8645 42V LMP8640HV 76V LMP8645HV 76V According to the shunt resistor Rsns to the gain of LMP8640 LMP8645 and to the supply voltage different ranges of currents can be sensed with this evaluation board 3 3 Components On the evaluation board there are already the circuit and the footprint of a standard dual op...

Page 3: ... 2 V to 46 V for LMP8640 LMP8645 or 2 V to 76 V for LMP8640HV LMP8645HV 4 2 Gain Selection of LMP8645 The evaluation board is provided with a shunt resistor Rsns 10 mΩ 1 1W while two gain resistors Rg1 and Rg2 10 kΩ 1 ensure a gain of 2 V V for each current sense The Gain is evaluated according to formula in Equation 3 3 The gain resistor must be chosen such that the max output voltage does not ex...

Page 4: ...Tolerance Package Type C1 C3 Capacitor 0 01 μF 5 0603 C2 C6 Capacitor 1 μF 10 3216 18 C4 Capacitor 0 1 μF 10 0805 C5 C7 Capacitor 0 1 μF 10 0603 C_Filt1 C_Filt2 Capacitor 0805 CG1 CG2 Capacitor 0805 R1 R2 R3 R4 R5 R6 Resistor min 10 kΩ 1 0603 RG1 RG2 Resistor 10 0 kΩ 1 0603 Rsns Resistor 0 01 Ω 1 1W 2010 Rsns Resistor 0 01 Ω 0 1 1W 2512 R_Filt_1 R_Filt2 Resistor 5 0805 U3 Dual Op Amp SOT 8 1 Compo...

Page 5: ...he version of the PCB stuffed with LMP8640 will be the gain resistors RG1 RG2 The LMP8640 is a current sense with fixed gain so it doesn t require any external gain resistor Figure 2 Schematic Diagram 5 SNOA546C November 2009 Revised April 2013 Schematic Submit Documentation Feedback Copyright 2009 2013 Texas Instruments Incorporated ...

Page 6: ...www ti com Appendix B Layout Figure 3 Top Layer 6 Layout SNOA546C November 2009 Revised April 2013 Submit Documentation Feedback Copyright 2009 2013 Texas Instruments Incorporated ...

Page 7: ...www ti com Appendix B Figure 4 Bottom Layer PCB Layout 7 SNOA546C November 2009 Revised April 2013 Layout Submit Documentation Feedback Copyright 2009 2013 Texas Instruments Incorporated ...

Page 8: ...esponsible for compliance with all legal regulatory and safety related requirements concerning its products and any use of TI components in its applications notwithstanding any applications related information or support that may be provided by TI Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which anticipate dangerous consequences of failur...

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