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Low Rho (LoRho) PPTC

KK WuProduct Manager

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What is Rho

Rho (ρ) is resistivity– ρ is material specific– The resistance of a conductive

material depends on theresistivity, area and length of it.

– Same size of material, the lower resistivity, the lower R.

R = ρL A

L = lengthA = Area

A

L

ρ

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Lo Rho SMD PTC introduction

New technology from material level– Carbon Black Ceramic powder– Polyethylene Improved bonding to foil

Benefits– Holding Current ▲– Resistance ▼– Size / Thickness ▼

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New SL series SMD PPTC devices

Low resistance SMD PPTC Devices (SL Series)Low resistance SMD PPTC Devices (SL Series)

Similar to regular SMD PPTC, but different material to reduce resistance & profile to fit into PCM module (<0.75mm)

Space and resistance demanding applications like battery pack OC protection.

Reduce inventory cost & shorten design & approval period for battery applications

Products• 1812L190SL • 1210L200SL• 1206L110SL, 1206L150SL• 0805L110SL

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New 06SL190G PTC battery strap

Advanced PTC strap for high efficiency battery pack application.

Major electrical characteristics: Ihold at 1.9A, Vmax 6V and Imax 50A, Rmin 0.006, Rmax 0.013 & R1max

0.024ohm Production ready to ramp up

NEW

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Advantages of SL PPTC

1) By offering super low resistance, ensure a low Voltage drop in application• Possibility of long cable in the design• Increased endurance of battery• Flexibility of power trace design

Standard PPTC Vs SL Series

Product Ihold (A) R1max (mΩ)Max Voltage Drop

(V) @ 1A

1206L150THWR 1.5 120 0.12

1206L150SLYR 1.5 55 0.055

Current Limit Switch Vs SL PPTC

ProductContinuous Current (A)

Typical Resistance (mΩ) @ 1A

Max Voltage Drop (V) @ 1A

Current Limit Switch 1.5 110 0.11

1206L150SLYR 1.5 40 0.04

54%

64%

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Advantages of SL PPTC

Size 0603 0805 1206 1210I hold (A) 1.50 2.00 3.00 3.50

2) High Hold Current with small footprint

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Advantages of SL PPTC

3) Comply with the latest UL/IEC 60950-1:2500(2nd edition)

• To Provide the most reliable protection under high current limiting scenarios, ratings with hold Current less than 3.5A are able to meet 8A/5S

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LoRho PTC applications

High Ihold solution (Extreme motherboard) Space is limited (Netbook) Height is limited (Mobile Internet Device) USB 3.0 ( low Voltage Drop is required)

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Lo Rho PTC for Battery application

Lo Rho SMD PTC in Battery PCM modules– Ultra low resistance– Labor saving

Battery strap / Spot welding SMD / Automation Assembly

– Easier to assemble

Lo Rho Strap– Ultra low resistance

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Appendix

PPTC basics

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PTC Characteristics and Device Physics

— PTC represents the Positive Temperature Coefficient, the resistance increases as temperature goes up.

— PTC device is made of polymer which is the plastic material used to produce the resettable PTC

— PTC device is resettable that will reset when cooled as compared to the action of a typical “one time” fuse

PTC Electrical Characteristics

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PTC Characteristics and Device PhysicsPPTC Current Conduction Mechanism

Conductive material (Carbon Black) is blended with non-conductive polymer (High Density Poly-Ethylene)

Normal Operation: Carbon black is concentrated between the polymer crystal boundaries and provides a low resistance path

Overload: At critical temperature (achieved through i2R heating), polymer volume expands as crystals melt, breaking the carbon black chains. The result is a very high resistance path.

Resetting: The fault must be removed, then the device will begin to cool. As it cools, the carbon black is pushed back into the crystal boundaries and resistance will decrease back to a value close to its initial value.