LM5009EVAL National Semiconductor, LM5009EVAL Datasheet

LM5009EVAL

Manufacturer Part Number

LM5009EVAL

Description

BOARD EVALUATION LM5009

Manufacturer

National Semiconductor

Series

PowerWise®r

Datasheets

1.LM5009MMNOPB.pdf (16 pages)

2.LM5009EVAL.pdf (10 pages)

Specifications of LM5009EVAL

Main Purpose

DC/DC, Step Down

Outputs And Type

1, Non-Isolated

Voltage - Output

10V

Current - Output

150mA

Voltage - Input

12 ~ 95V

Regulator Topology

Buck

Frequency - Switching

240Hz

Board Type

Fully Populated

Utilized Ic / Part

LM5009

Lead Free Status / RoHS Status

Not applicable / Not applicable

Power - Output

Lead Free Status / Rohs Status

Not Compliant

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LM5009 Evaluation Board

Introduction

The LM5009EVAL evaluation board provides the design en-

gineer with a fully functional buck regulator, employing the

constant on-time (COT) operating principle. This evaluation

board provides a 10V output over an input range of 12V - 95V.

The circuit delivers load currents to 150 mA, with current limit

nents except C6 and C9. These components provide options

for managing the output ripple as described later in this doc-

ument.

Theory of Operation

Refer to the evaluation board schematic in Figure 5, which

contains a simplified block diagram of the LM5009. When the

circuit is in regulation, the buck switch is on each cycle for a

time determined by R1 and the input voltage according to the

equation:

The nominal switching frequency is calculated from:

The on-time in this evaluation board ranges from

Vin = 12V, to

versely with V

quency, which is nominally 240 kHz in this evaluation board .

At the end of each on-time the Minimum Off-Timer ensures

the buck switch is off for at least 300 ns. In normal operation

the off-time is much longer. During the off-time the output ca-

≊

240 mA. The board is populated with all external compo-

≊

450 ns at Vin = 95V. The on-time varies in-

to maintain a nearly constant switching fre-

201811

FIGURE 1. Evaluation Board - Top Side

≊

3540 ns at

National Semiconductor

Application Note 1445

Dennis Morgan

February 14, 2011

The board’s specification are:

•

pacitor (C2) is discharged by the load current. When the

output voltage falls sufficiently that the voltage at FB is below

2.5V, the regulation comparator initiates a new on-time peri-

od. For stable, fixed frequency operation,

is required at FB to switch the regulation comparator. Refer

to the LM5009 data sheet for a more detailed block diagram,

and a complete description of the various functional blocks.

Board Layout and Probing

The pictorial in Figure 1 shows the placement of the circuit

components. The following should be kept in mind when the

board is powered:

1) When operating at high input voltage and high load current,

forced air flow is recommended.

2) The LM5009 may be hot to the touch when operating at

high input voltage and high load current.

3) Use CAUTION when probing the circuit at high input volt-

ages to prevent injury, as well as possible damage to the

circuit.

4) Ensure the wires connecting this board to the load are sized

appropriately for the load current. Ensure there is not a sig-

nificant drop in the wires between this evaluation board and

the load.

Input Voltage: 12V to 95V

Output Voltage: 10V

Maximum load current: 150 mA

Minimum load current: 0 mA

Current Limit:

Measured Efficiency: 93.3% (V

Nominal Switching Frequency: 240 kHz

Size: 1.6 in. x 1.0 in. x 0.5 in

≊

240 mA

20181101

= 12V, I

≊

25 mVp-p of ripple

OUT

www.national.com

= 100 mA)

Related parts for LM5009EVAL

LM5009EVAL Summary of contents

Page 1

... LM5009 Evaluation Board Introduction The LM5009EVAL evaluation board provides the design en- gineer with a fully functional buck regulator, employing the constant on-time (COT) operating principle. This evaluation board provides a 10V output over an input range of 12V - 95V. The circuit delivers load currents to 150 mA, with current limit ≊ ...

Page 2

Board Connection/Start-up The input connections are made to the J1 connector. The load is normally connected to the V1 and GND terminals of the J3 connector. Ensure the wires are adequately sized for the in- tended load current. Before start-up ...

Page 3

B) Intermediate Ripple Level Configuration: This configu- ration generates more ripple at V than the above config- OUT1 uration, but uses one less capacitor. If some ripple can be FIGURE 3. Intermediate Ripple Level Configuration Using C6 and R4 ≥ ...

Page 4

Current Limit The LM5009 contains an intelligent current limit off-timer. The current limit threshold is 310 mA, ±60 mA. If the current in the buck switch (the peak of the inductor’s current waveform) reaches the threshold the present on-time cycle ...

Page 5

... TDK C2012X7R2A222M TDK C2012X7R2A103M Unpopulated Diodes Inc. DFLS1100 Power DI 123 TDK SLF7045T-221MR33 Vishay CRCW08053403F CRCW08053K01FKEA CRCW08051K00FKEA Vishay CRCW0805000Z Vishay CRCW08052553F Vishay CRCW08051153F National Semiconductor LM5009MM 5 Package Value 1210 1.0 µF, 100V 1210 22 µF, 16V 0805 0.1 µF, 100V 0805 0.022 µF, 100V ...

Page 6

Circuit Performance FIGURE 6. Efficiency vs Load Current FIGURE 7. Efficiency vs Input Voltage www.national.com 20181112 FIGURE 8. Output Voltage Ripple 20181113 FIGURE 9. Switching Frequency vs. Load Current 6 20181114 20181115 ...

Page 7

PCB Layout Board Silkscreen Board Top Layer 7 20181116 20181117 www.national.com ...

Page 8

Board Bottom Layer (viewed from top) 8 20181118 ...

Page 9

9 www.national.com ...

Page 10

... For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock and Timing www.national.com/timing Data Converters www.national.com/adc Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www.national.com/ldo LED Lighting www ...

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