Rev1; Aug 1, 2006

2Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

AC mains

DC input

Power supply

LCD TVApplication Guide

Audio in/out

CATV in

Composite video

Ethernet port

HDMI port

COAX (F-type)

S-Video

Satellite in

SCART interface

VGA port

USB 1.1 port

USB 2.0 port

Terrestrial in

Audio/videoCommunications

Data ports

IEEE 1394 Backlight inverter

3Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Block Diagram of LCD TV

4Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of IEEE 1394 port

Design Notes:

Protection Application: IEEE 1394 uses a low-voltage differential signaling system operating between 1.20V to 2.00V, with a maximum data rate of 400 Mbps (1394a) to 1,600 Mbps (1394b). At these data rates, the capacitance of the suppressor needs to be minimized. The signal lines to be protected against ESD include TPA+, TPA-, TPB+ and TPB-. The 30VDC power bus should be protected against ESD and overcurrent events.

Solution Description: As shown at the left, a multilayer varistor is used on the power bus for ESD protection, and a PTC is used for resettable overcurrent protection. For the data lines, discrete PulseGuard® suppressors can be used for board layout flexibility, or to reduce part count, a single PulseGuard array can be used.

Companion Solutions: Other solutions within the LF portfolio exist in addition to these recommendations. For example, leaded PTCs can be substituted for the SMD versions, or a TVS diode can be substituted for the MLV.

Regulatory Issues: The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.

Unique Features: Does not apply.

Application Warnings: It is recommended that only resettable protection devices like PTCs be used on hot-plug ports like 1394.

5Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of USB 1.1 port

Design Notes:

Protection Application: The data signals used in a USB 1.1 port vary between -0.5V to +0.5V, with a maximum data rate of 12Mbps. At this data rate, the capacitance of the suppressor needs to be taken into account. The signal lines to be protected from ESD include D+ and D-. The 5VDC power bus should be protected against ESD and overcurrent events.

Solution Description: As shown at the left, a multilayer varistor is used on the power bus for ESD protect, and a PTC is used for resettable overcurrent protection. For the data lines, discrete multilayer varistors can be used for board layout flexibility, or to reduce part count, a single Diode array can be used.

Companion Solutions: Other solutions within the LF portfolio exist in addition to these recommendations. For example, if the operating current on the power bus is higher or lower, an appropriately rated PTC can be chosen.

Regulatory Issues: The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.

Unique Features: Does not apply.

Application Warnings: Does not apply.

6Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of USB 2.0 port

Design Notes:

Protection Application: The data signals used in a USB 2.0 port vary between -0.5V to +0.5V, with a maximum data rate of 480Mbps. At this data rate, the capacitance of the suppressor needs to be minimized. The signal lines to be protected from ESD include D+ and D-. The 5VDC power bus should be protected against ESD and overcurrent events.

Solution Description: As shown at the left, a multilayer varistor is used on the power bus for ESD protect, and a PTC is used for resettable overcurrent protection. For the data lines, discrete PulseGuard® suppressors can be used for board layout flexibility, or to reduce part count, a single PulseGuard array can be used.

Companion Solutions: Other solutions within the LF portfolio exist in addition to these recommendations. For example, if the operating current on the power bus is higher or lower, an appropriately rated PTC can be chosen.

Regulatory Issues: The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.

Unique Features: Does not apply.

Application Warnings: Does not apply.

7Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of Ethernet Port

Design Notes:

Protection Application: The data signals used in an Ethernet port vary between 1.0V (100 and 1,000 BaseT) to 2.5V (10BaseT), with maximum data rates of 125Mbps and 12.5Mbps, respectively. At these data rates, the capacitance of the suppressor needs to be taken into account. The signal lines to be protected from ESD include T+/- and R+/-.

Solution Description: As shown at the left, discrete multilayer varistors can be used for board layout flexibility, or to reduce part count, a single rail clamp array can be used.

Companion Solutions: Other solutions within the LF portfolio exist in addition to these recommendations. For example, if the design engineer knows that no additional capacitance can be added to the system, the PulseGuard® suppressor family can be consulted.

Regulatory Issues: The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.

Unique Features: Does not apply.

Application Warnings: This protection scheme is only for Ethernet ports that connect to a LAN. If the Ethernet network will include access to the outside of the building, then more stringent standards apply to take into account lightning surges. Please consult Littelfuse recommendations for Ethernet and Intrabuilding surge protection.

8Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of Backlight Inverter Circuit in LCD PanelDesign Notes:

Protection Application: The backlight inverter circuit controls the action of the fluorescent tubes that light the LCD panels. The DC input should be protected against overcurrent and surge voltage events. The bus is typically rated between 9 and 14 VDC.

Solution Description: As shown at the left, a fuse should be used for short circuit and overload current conditions. Typically, for small LCD panels (15” to 21”), chip fuses can be used. For larger panels (> 21”), the SMD Nano2 fuse is recommended. For surge protection, an MLV or TVS diode can be used.

Companion Solutions: Does not apply.

Regulatory Issues: Does not apply.

Unique Features: Does not apply.

Application Warnings: Note that it is very important that the fuse is selected carefully. Since fuses are thermal devices, the ambient temperature in their vicinity will affect their performance. In order to ensure proper performance and to avoid nuisance opening, the fuse selection process should take into account the ambient temperature and de-rate the fuse appropriately.

9Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of Video in/outDesign Notes:

Protection Application: The video signals used in S-video and Composite video formats vary between 0.5 and 2.0Vp-p, with a maximum frequency of 5MHz. At this frequency, the capacitance of the suppressor needs to be taken into account. The signal lines to be protected from ESD include Luminance and Chrominance for S-video, and the single conductor for Composite video.

Solution Description: As shown at the left, discrete multilayer varistors are recommended for protection. Due to the analog nature of the video signals, uni-polar TVS diode arrays are not recommended as the may clip the negative part of the video signal.

Companion Solutions: Other solutions within the LF MLV portfolio exist in addition to these recommendations. For example, if the manufacturing process cannot handle 0402-size components, devices with the same characteristics can be found in 0603-size components.

Regulatory Issues: The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.

Unique Features: Does not apply.

Application Warnings: The F-type connector shown at the left is specifically for set top box-to-monitor video circuits. If the F-type connector is for CATV or Satellite inputs, then lightning surges become a concern and MLVs cannot be used. In this case, GDTs are required. See the page on CATV and Satellite inputs for more details.

10Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of SCART Interface

Design Notes:

Protection Application: In the SCART interface, there are 12 signal and control lines to be protected against ESD. The signals used include video (up to 5 MHz and 2.0Vp-p), audio (up to 30 kHz and 12Vp-p) and control (up to 3 MHz and 12V). For the video and control lines, the capacitance of the suppress should be taken into account.

Solution Description: As shown at the left, discrete multilayer varistors can be used for board layout flexibility. These parts will meet the capacitance requirements for the video and control lines, as well as the stand-off voltage requirement for the audio lines.

Companion Solutions: Other solutions within the LF portfolio exist in addition to these recommendations. For example, if arrays were preferred for part count reductions, products like the SP723ABT should be considered.

Regulatory Issues: The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.

Unique Features: Does not apply.

Application Warnings: Does not apply.

11Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of VGA Port

Design Notes:

Protection Application: The signal lines used in a VGA port have a maximum frequency of 25 MHz, and are 0.7 Vp-p for R, G, and B lines, and 0.3 to 5.0 Vp-p for ID01, ID02, ID03, H-sync and V-sync. For these lines, the capacitance of the suppress needs to be taken into account.

Solution Description: As shown at the left, discrete multilayer varistors can be used for board layout flexibility, or to reduce part count, two rail clamp devices can be used.

Companion Solutions: Does not apply.

Regulatory Issues: The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.

Unique Features: Does not apply.

Application Warnings: Does not apply.

12Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of Audio In/Out

Design Notes:

Protection Application: Audio signals can have a maximum value of 12Vp-p, and a maximum frequency less than 30kHz. At this frequency, the capacitance of the suppressor does not need to be taken into account. The signal lines to be protected from ESD are the left and right channels.

Solution Description: As shown at the left, discrete multilayer varistors can be used for layout flexibility. Due to the analog nature of the audio signals, uni-polar TVS diode arrays are recommended only if the negative part of the signal is -0.5V or less since they may clip this part of the audio signal if the magnitude is larger.

Companion Solutions: Other solutions within the LF MLV portfolio exist in addition to these recommendations. For example, if the manufacturing process cannot handle 0402-size components, devices with the same characteristics can be found in 0603-size.

Regulatory Issues: The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.

Unique Features: Does not apply.

Application Warnings: Does not apply.

13Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of HDMI Port

Design Notes:

Protection Application: The data signals used in High Definition Multimedia Interface ports vary between approximately 2.5V and 3.5V, and have a data rate of 1,600Mbps. The signal lines to be protected from ESD include R+, R-, G+, G-, B+, B-, Cl+ and Cl-.

Solution Description: Due to the extremely high rate of data transfer, the capacitance of the ESD suppressor must be minimized. As shown at the left, discrete PulseGuard® suppressors can be used for board layout flexibility, or to reduce part count, array versions can be used.

Companion Solutions: Does not apply.

Regulatory Issues: The IEC 61000-4-2 will be the most appropriate standard that applies for this port. It supplies a test method for verifying that the end product is not susceptible to ESD events.

Unique Features: The PulseGuard solution has the industry’s lowest capacitance value. This feature ensures that it will maintain the signal integrity of high-speed data ports.

Application Warnings: Does not apply.

14Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of CATV/Satellite/Terrestrial InputsDesign Notes:

Protection Application: The broadcast signals carried by these various inputs operate in the radio frequency range. The frequencies extend up to 806 MHz for analog TV, 698 MHz for Digital TV, 1,000 MHz for CATV and 2,500 MHz for Satellite transmissions. Due to the high frequency nature of these signals, the capacitance of the suppressor must be taken into account to avoid signal attenuation. The electrical threats will be lightning surges and ESD.

Solution Description: As shown at the left, a single gas discharge tube is used to protect the input signal line. The specific part number is determined by matching the surge’s peak pulse current value to that of the appropriate GDT.

Companion Solutions: Does not apply.

Regulatory Issues: Since this input is susceptible to lightning transients, standards such as UL 1449 and IEC 61000-4-5 should be consulted for test conditions. Typically, the 8x20s waveform is used.

Unique Features: Does not apply.

Application Warnings: PulseGuard® suppressors also have very low capacitance values, but should not be used on this input line. The PulseGuard devices are not robust enough to protect against lightning transients; they are specifically designed for ESD protection.

15Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of AC Mains

Design Notes:

Protection Application: Products that are directly connected to the AC mains (120 to 250VACrms) will be exposed to much more severe surge transients (lightning, load switching, etc.) and short circuit/overload conditions than on DC inputs. Because of this, the protection devices need to be more robust.

Solution Description: As shown at the left (top), a cartridge or leaded fuse (Pico, 5x20mm, 2AG, 3AG, TE5/TR5) can be used for short circuit and overload current conditions. For surge protection, an MOV should be used. The MOV should be selected based on the expected severity (energy, voltage and peak pulse current) of the transient surge. The specific family (C-III, UltraMOV or LA) can be determined after the surge severity is understood.

Companion Solutions: Does not apply.

Regulatory Issues: Standards will vary depending on the product to be protected. Examples include:

• IEC 61000-4-5

• UL1414

• UL1449

Unique Features: Does not apply.

Application Warnings: When selecting the fuse, be sure to consider the expected temperature in the area around the fuse, as well as the in-rush currents. Failure to take these factors into account may result in premature or nuisance tripping of the fuse.

16Confidential and Proprietary to Littelfuse, Inc. © 2006 Littelfuse, Inc. All rights reserved.

LCD TV

Circuit Protection of DC input

Design Notes:

Protection Application: For products that include an external AC adapter, a DC voltage (typically in the range of 5VDC to 18VDC) will be supplied. The electrical threats include lightning surges, ESD and overcurrent conditions (short circuit or overload).

Solution Description: As shown at the left, a fuse or PTC can be used for short circuit and overload current conditions. For surge and ESD protection, an MOV (e.g. LA series) or TVS diode (e.g. P4KE or P4SMA series) can be used.

Companion Solutions: Note that the magnitude of the surge transient should be understood as this can point to alternative solutions. For example, if more severe surges are expected, then C-III or UltraMOV varistors or higher-rated diodes (e.g. 600W, 1,500W) can be selected. If the only threat is expected to be ESD, then multilayer chip varistors can be selected.

Regulatory Issues: If ESD is a concern, the IEC 61000-4-2 can be consulted to find information on the test method and transient waveform that should be used.

Unique Features: Does not apply.

Application Warnings: Does not apply.