Texas Instruments LM25085A User Manual Download Page 7

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Bill of Materials

Bill of Materials

Table 1. Bill of Materials

Item

Description

Mfg., Part Number

Package

Value

C1, C2, C11

Ceramic Capacitor

Taiyo Yuden

1210

10 µF, 35V

GMK325BJ106KN

Ceramic Capacitor

TDK C2012X7R1C474K

0805

0.47 µF, 16V

Ceramic Capacitor

TDK C2012X7R2A102K

0805

1000 pF, 100V

Unpopulated

0805

Ceramic Capacitor

TDK C3225X5R0J686M

1210

68 µF, 6.3V

Unpopulated

Ceramic Capacitor

TDK C2012X7R2A104K

0805

0.1 µF, 100V

Ceramic Capacitor

TDK C2012X7R2A103K

0805

0.01 µF, 100V

C10

Ceramic Capacitor

TKD C2012X7R2A332K

0805

3300 pF, 100V

Schottky Diode

On Semi

D2PAK

35V, 25A

MBRB2535CTL

Power Inductor

Wurth XXL 7447709006

12 mm x 12 mm

6.8 µH

P-Channel MOSFET

Vishay Si7465DP

SO-8 Power

60V, 5A

Resistor

Vishay

0805

1.1k

CRCW08051101F

Resistor

Vishay

0805

10k

CRCW08051002F

Resistor

Vishay

0805

2.05k

CRCW08052051F

Resistor

Vishay

0805

21k

CRCW08052102F

Resistor

Vishay

2010

0.01 ohm,

WSL2010R0100F

Resistor

Vishay

0805

0 ohms

CRCW08050000Z

Resistor

Vishay

0805

48.7k

CRCW08054872F

Switching Regulator

LM25085

VSSOP8-EP

SNVA384B – February 2009 – Revised April 2013

AN-1933 LM25085A Evaluation Board

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Summary of Contents for LM25085A

Page 1: ...ent limit set at 8 2A The board is populated with all components except C5 and C7 The board s specification are Input Voltage 4 5V to 24V Output Voltage 1V Maximum load current 5A Minimum load current 0A Current Limit Threshold 8 2A Measured Efficiency 77 5 VIN 4 5V IOUT 1Amp typical efficiency for converter providing a 1V output Nominal Switching Frequency 200 kHz Size 3 1 in x 1 5 in Figure 1 Ev...

Page 2: ...w the inductor current to decrease at least as much if not more than the current increase which occurred during the on time The circuit may be shutdown at any time by grounding the Enable test point EN TP1 Removing the ground connection allows normal operation to resume Refer to the LM25085A 42V Constant On Time PFET Buck Switching Controller with 0 9V Reference SNVS601 data sheet for a detailed b...

Page 3: ...g forced off time provides effective protection from output load faults over a wide range of operating conditions Figure 2 Current Limit Off time vs VIN and VFB A Sense resistor method This evaluation board is supplied configured for the sense resistor method of current limit detection Jumpers A B are in place at both jumper locations JP1 JP2 which connects the ADJ pin resistor R3 and the ISEN pin...

Page 4: ...nd C10 allowing the ripple at VOUT to be kept to a minimum as described in option A below Alternatively the required ripple at the FB pin can be supplied from ripple generated at VOUT and passed through the feedback resistors as described in options B and C below using one or two less external components A Minimum Output Ripple This evaluation board is supplied configured for minimum ripple at VOU...

Page 5: ... current flows through R6 and that ripple voltage is passed to the FB pin via C5 The ripple at VOUT can be set as low as 25 mVp p since it is not attenuated by R1 and R2 The minimum value for R6 is calculated from 10 where IOR min is the minimum inductor s ripple current which occurs at minimum input voltage and is 622 mAp p at 4 5V The minimum value for R6 calculates to 0 04 ohms Using a standard...

Page 6: ...t VOUT ranges from 32 mVp p to 43 mVp p over the input voltage range See Figure 10 If the application can accept this ripple level this is the most economical solution The circuit is shown in Figure 5 Figure 5 Lowest Cost Configuration 7 Monitor The Inductor Current The inductor s current can be monitored or viewed on a scope with a current probe Remove the jumper from the WIRE LOOP pads and insta...

Page 7: ...ic Capacitor TKD C2012X7R2A332K 0805 3300 pF 100V D1 Schottky Diode On Semi D2PAK 35V 25A MBRB2535CTL L1 Power Inductor Wurth XXL 7447709006 12 mm x 12 mm 6 8 µH Q1 P Channel MOSFET Vishay Si7465DP SO 8 Power 60V 5A R1 Resistor Vishay 0805 1 1k CRCW08051101F R2 Resistor Vishay 0805 10k CRCW08051002F R3 Resistor Vishay 0805 2 05k CRCW08052051F R4 Resistor Vishay 0805 21k CRCW08052102F R5 Resistor V...

Page 8: ...verter producing a 1 0V output Figure 7 Efficiency vs Load Current Figure 8 Efficiency vs Input Voltage Figure 9 Switching Frequency vs Input Voltage 8 AN 1933 LM25085A Evaluation Board SNVA384B February 2009 Revised April 2013 Submit Documentation Feedback Copyright 2009 2013 Texas Instruments Incorporated ...

Page 9: ...e 10 Output Voltage Ripple Figure 11 Line Regulation Figure 12 Load Regulation 9 SNVA384B February 2009 Revised April 2013 AN 1933 LM25085A Evaluation Board Submit Documentation Feedback Copyright 2009 2013 Texas Instruments Incorporated ...

Page 10: ...de Trace 4 Inductor Current Trace 3 VOUT Trace 1 SW Node VIN 12V IOUT 0 Figure 14 Discontinuous Conduction Mode Trace 4 Inductor Current Trace 3 VOUT Trace 1 SW Node VIN 12V IOUT 0 Figure 15 Discontinuous Conduction Mode Expanded Scale 10 AN 1933 LM25085A Evaluation Board SNVA384B February 2009 Revised April 2013 Submit Documentation Feedback Copyright 2009 2013 Texas Instruments Incorporated ...

Page 11: ...e 16 Board Silkscreen Figure 17 Board Top Layer Figure 18 Board Bottom Layer Viewed from Top 11 SNVA384B February 2009 Revised April 2013 AN 1933 LM25085A Evaluation Board Submit Documentation Feedback Copyright 2009 2013 Texas Instruments Incorporated ...

Page 12: ...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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