PC Board Layout
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Figure 15. Board Second Layer (Viewed from Top)
10
AN-1650 LM34919 Evaluation Board
SNVA250A – June 2007 – Revised April 2013
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Copyright © 2007–2013, Texas Instruments Incorporated
Page 1: ...all components except R5 C9 and C10 These components provide options for managing the output ripple as described later in this document The board s specification are Input Voltage 8V to 40V Output Voltage 5V Maximum load current 600 mA Minimum load current 0A Current Limit 640 mA to 730 mA Measured Efficiency 92 7 VIN 8V IOUT 300 mA Nominal Switching Frequency 800 kHz Size 2 6 in x 1 6 in x 0 5 in...
Page 2: ...o the circuit 4 At maximum load current 0 6A the wire size and length used to connect the load becomes important Ensure there is not a significant drop in the wires between this evaluation board and the load 4 Board Connection Start up The input connections are made to the J1 connector The load is connected to the J2 OUT and J3 GND terminals Ensure the wires are adequately sized for the intended l...
Page 3: ...tion Since the output ripple is passed by Cff to the FB pin with little or no attenuation R4 can be reduced so the minimum ripple at VOUT is 25 mVp p The minimum value for Cff is calculated from 2 where tON max is the maximum on time at minimum VIN and R2 R3 is the parallel equivalent of the feedback resistors See Figure 8 Option C Minimum Ripple Configuration To obtain minimum ripple at VOUT R4 i...
Page 4: ...is 3000 to 5000 pF and R5 is 10kΩ to 300 kΩ C9 is chosen large compared to C10 typically 0 1 µF See Figure 4 and Figure 8 Figure 4 Minimum Output Ripple Configuration 6 Monitor The Inductor Current The inductor s current can be monitored or viewed on a scope with a current probe Remove R6 and install an appropriate current loop across the two large pads where R6 was located In this way the inducto...
Page 5: ...603 0 1 µF 50V C4 Ceramic Capacitor TDK C1608X7R1H104K 0603 0 1 µF 50V C5 C6 Ceramic Capacitor TDK C1608X7R1H223K 0603 0 022 µF 50V C7 C8 Ceramic Capacitor TDK C3216X7R1C106K 1206 10 µF 16V C9 Ceramic Capacitor Unpopulated 0603 C10 Ceramic Capacitor Unpopulated 0603 D1 Schottky Diode Zetex ZLLS2000 SOT23 6 40V 2 2A L1 Power Inductor Bussman DR73 150 7 6 mm x 7 6 mm 15 µH 1 8A R1 Resistor Vishay CR...
Page 6: ...igure 6 Efficiency vs Load Current Figure 7 Efficiency vs Input Voltage Figure 8 Output Voltage Ripple 6 AN 1650 LM34919 Evaluation Board SNVA250A June 2007 Revised April 2013 Submit Documentation Feedback Copyright 2007 2013 Texas Instruments Incorporated ...
Page 7: ... 9 Switching Frequency vs Input Voltage Figure 10 Load Current Limit vs Input Voltage 7 SNVA250A June 2007 Revised April 2013 AN 1650 LM34919 Evaluation Board Submit Documentation Feedback Copyright 2007 2013 Texas Instruments Incorporated ...
Page 8: ...out 400 mA Figure 11 Continuous Conduction Mode Trace 4 VOUT Trace 3 inductor Current Trace 2 SW Pin Vin 24V Iout 20 mA Figure 12 Discontinuous Conduction Mode 8 AN 1650 LM34919 Evaluation Board SNVA250A June 2007 Revised April 2013 Submit Documentation Feedback Copyright 2007 2013 Texas Instruments Incorporated ...
Page 9: ...t 11 PC Board Layout Figure 13 Board Silkscreen Figure 14 Board Top Layer 9 SNVA250A June 2007 Revised April 2013 AN 1650 LM34919 Evaluation Board Submit Documentation Feedback Copyright 2007 2013 Texas Instruments Incorporated ...
Page 10: ...out www ti com Figure 15 Board Second Layer Viewed from Top 10 AN 1650 LM34919 Evaluation Board SNVA250A June 2007 Revised April 2013 Submit Documentation Feedback Copyright 2007 2013 Texas Instruments Incorporated ...
Page 11: ...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...
