ISL6841EVAL3Z Intersil, ISL6841EVAL3Z Datasheet

ISL6841EVAL3Z

Manufacturer Part Number

ISL6841EVAL3Z

Description

EVALUATION BOARD FOR ISL6841

Manufacturer

Intersil

Datasheets

1.ISL6840IUZ-T.pdf (12 pages)

2.ISL6841EVAL3Z.pdf (10 pages)

Specifications of ISL6841EVAL3Z

Main Purpose

DC/DC, Step Down

Outputs And Type

1, Isolated

Voltage - Output

12V

Current - Output

2.5A

Voltage - Input

18 ~ 30V

Regulator Topology

Flyback

Frequency - Switching

300kHz

Board Type

Fully Populated

Utilized Ic / Part

ISL6841

Lead Free Status / RoHS Status

Lead free / RoHS Compliant

Power - Output

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Choice of PWM Controller

The ISL684x family of devices are superior performing pin

compatible replacements for the industry standard 384x

single-ended current mode PWM controllers. Also available

in 8 Ld MSOP and 8 Ld SOIC, the ISL6841 in the space

saving 2mmx3mm DFN package is used in the

ISL6841EVAL3Z evaluation board.

The design requirements of this application require the

superior performance characteristics of the ISL6841. Some

key features of this part include:

• Tight internal voltage reference of 1%.

• 40ns peak current sensing.

• Internal 1A MOSFET driver.

The ISL6841 was selected for its UVLO threshold and its

50% maximum duty cycle limit. In addition, its low UVLO

start threshold would help in easily modifying the design in

catering to lower input voltage applications.

Topology Selection

This evaluation board was designed to allow for maximum

flexibility, targeting applications that use a typical battery

input of 24V. Given the low input voltages for this application,

a single-ended topology would be ideal. The flyback

topology was selected for the low power levels targeted by

this application with emphasis on low BOM cost. Continuous

conduction mode of operation was chosen to achieve higher

efficiencies at the expense of lower bandwidth of operation,

a direct consequence of transition from continuous to

discontinuous mode of operation.

For feature-rich applications that need short-circuit

protection, over-temperature shutdown, etc., the ISL6841

may be substituted with the ISL6721. This evaluation board

has been provided with placeholders for primary auxiliary

winding feedback to save component cost in case of

applications that can tolerate loose regulation requirements.

Application Note

ISL6841EVAL3Z Evaluation Board for General

1-888-INTERSIL or 1-888-468-3774

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

Purpose Industrial Applications

Target Design Specifications

The following design requirements were targeted for

evaluation purposes:

• Switching Frequency, f

• V

• I

• P

• Full Load Efficiency: 80% minimum under all line

• Ripple: 1% of output voltage.

• Form Factor: 2”x2”.

The detailed design procedure for a continuous mode

flyback topology has been discussed in the application note

AN1192, available on Intersil’s website:

http://www.intersil.com/data/an/an1192.pdf

Typical Performance Characteristics

The major performance criterion for the converter are

efficiency, load regulation and low output ripple. As can be

observed from the following figures, the 20% load efficiency

target of 80% has been comfortably met under all input

voltage conditions. Tight load regulation has been achieved

by using the opto-coupled feedback scheme.

Waveforms

Typical waveforms can be found in the following Figures.

Figure 1 shows the efficiency curves at different input

voltages. Figure 2 shows the worst case output voltage

ripple and noise.

Figures 3 through 6 show the drain and gate waveforms of

the primary FET under different input and loading conditions.

Figures 7 through 10 show the secondary rectifier

waveforms under different input and loading conditions.

A measure of the stability can be determined from the Bode

plots shown in Figures 11 through 14. As shown, the gain

and phase margins under the extreme conditions of line and

load indicate a stable system under all operating conditions.

conditions, and loads of 20% and above.

OUT

February 12, 2008

OUT

: 18VDC to 30VDC.

: 2.5A.

: 12V with 5% absolute regulation.

: 30W.

All other trademarks mentioned are the property of their respective owners.

Intersil (and design) is a registered trademark of Intersil Americas Inc.

: 200kHz.

AN1384.0

Related parts for ISL6841EVAL3Z

ISL6841EVAL3Z Summary of contents

Page 1

... ISL6841EVAL3Z Evaluation Board for General Purpose Industrial Applications February 12, 2008 Target Design Specifications The following design requirements were targeted for evaluation purposes: • ...

Page 2

FIGURE 2. OUTPUT RIPPLE AND NOISE, 20MHz BW FIGURE 4. FET VOLTAGES 30V, LOAD = 250mA IN 2 Application Note 1384 18V 24V 30V 0 0.25 0.50 ...

Page 3

FIGURE 6. FET VOLTAGES 30V, LOAD = 2.5A IN FIGURE 8. RECTIFIER WAVEFORM LOAD = 250mA FIGURE 10. RECTIFIER WAVEFORM Application Note 1384 FIGURE 7. RECTIFIER WAVEFORM 30V, FIGURE 9. RECTIFIER WAVEFORM, ...

Page 4

Application Note 1384 FIGURE 11. STABILITY ANALYSIS, V FIGURE 12. STABILITY ANALYSIS 18V, FULL LOAD IN = 18V, NO LOAD IN AN1384.0 February 12, 2008 ...

Page 5

Application Note 1384 FIGURE 13. STABILITY ANALYSIS, V FIGURE 14. STABILITY ANALYSIS 30V, FULL LOAD IN = 30V, NO LOAD IN AN1384.0 February 12, 2008 ...

Page 6

... ISL6841EVAL3Z Schematic ...

Page 7

... Using a high performance, low-cost PWM controller with a low pin-count, all the design targets have been achieved, while keeping the cost to a minimum. The ISL6841EVAL3Z schematic and BOM for the evaluation board are provided as follows. Please contact our Technical Support Center for custom output voltage requirements. They can be reached through Intersil’ ...

Page 8

Component List REFERENCE DESIGNATOR VENDOR C1 Panasonic C2, C6 TDK/Murata C3 TDK/Murata C4 TDK/Murata C5 Sanyo C7, C18 TDK/Murata C8, C12 TDK/Murata C9 TDK/Murata C10, C11 TDK/Murata C15 TDK/Murata C16 TDK/Murata C17 Murata D1 Diodes D2, D5 Diodes D3 ...

Page 9

... REFERENCE DESIGNATOR VENDOR R19, R22 R20 R21 T1 TDK T2 Pulse U1 Intersil U2 California Eastern Laboratories 9 Application Note 1384 PART NUMBER RES, SMD, 0402, 10k, 1/16W, 1%, TF, ROHS RES, SMD, 0402, 6.34k, 1/16W, 1%, TF, ROHS RES, SMD, 0402, 3.83k, 1/16W, 1%, TF, ROHS DCT20EFD-U42S004 TRANSFORMER-FLYBACK, SMD, 20µH, CUSTOM, ROHS P8205NL TRANSFORMER-CURRENT SENSE, SMD, 8P, 500µ ...

Page 10

... Layout The ISL6841EVAL3Z board met the form factor target with room to spare. Following are the layout pictures of the board. The gerber files are available upon request. FIGURE 17. SILKSCREEN - TOP LAYER FIGURE 19. ETCH - TOP LAYER FIGURE 21. ETCH - LAYER 3 Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding ...

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