Low ESL Current Sensing Low Resistance Chip Resistors

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Current sensing low resistance chip resistors have become indispensable components for the power management of mobile and other devices. The requirements for such resistors used to be tight tolerance, small TCR, high power and small size; however, as signal processing speed and switching frequency have increased, parasitic noises for these components has become a significant issue.

Low ESL Resistor

The RL/PRL series, Susumu’s long side terminal current sensor chip resistors have shorter and wider resistive elements compared to their conventional short side terminal counterparts. Due to this reason, they have much less parasitic inductance (ESL), hence, less noise (see Figure 1). Figure 2 shows the pulse shape with a longer side terminal chip (left) vs. a shorter side terminal chip. The reduction of noise of the longer side terminal chip is expressed in pulse shape is demonstrated.

 

ADVANTAGES Low ESL – low noise No hot spots (smallest size for required wattage) Low TCR and tight resistance tolerance (±0.5%) Complete RoHS compliant

 

 

 

All electronics devices are shrinking but, at the same time, requiring more power with multiple functionalities. Components are required to be smaller but must also be able to handle more power. For current sensing low resistant resistors, thin-film specialist, Sususmu, offers the world’s smallest low resistance chip resistors for unit power. For example, our PRL1632 can handle 1W, while industry typical wattage for this size is 1/4W. We start with our proprietary metal alloy for resistive film. Our patented structural design and distribution of resistive material allow even heat distribution throughout the component eliminating hot spots unlike our competitors’ products. In addition, using alumina substrate makes heat dissipation quick and efficient.

The structural design and material choice also minimize inductive component of this product, increase the tolerance to high voltage pulses and supplying excellent over-current protection.

 

 

FEATURES Smallest size for required wattage Highest wattage for required size Excellent current surge tolerance Offered in two popular sizes, 1220, 1632 Resistance range 1mΩ to 100Ω

 

 

ADVANTAGES Space saving for required wattage Highest power for available space Over current protection by becoming open (PRL) Attractive pricing Good RF4 board compatibility – no heat burns! Offered in two configurations – longer side terminal and standard shorter side terminal

 

APPLICATIONS Any application that requires current sensing low resistance resistors such as protection and control circuits.

 

 

 

More on Heat Distribution

Here we show a simple diagram demonstrating how heat from resistive film is distributed evenly across the component. Unlike other resistors that have the resistive element in the center of the chip, we have split the resistive element into 2 parts and placed heat dissipative electrode between them. This simple innovative idea has solved the problem of the hot spot. This innovation is even more obvious when comparing our products with bulk type current sensors.

 

 

 

Low Reactance/Inductance

High inductance disturbs signal integrity and creates noise. The choice of material, structural, and trace design of PRL products serves to minimize the amount of inductance/reactance.

 

 

Strong Tolerance to Current/Voltage Surge

The tolerance to high voltage/current surge is related to how the passivation materials and the structure of the component can handle sudden increase of temperature. Susumu’s RL and PRL series that incorporate select materials and structural designs are able to handle such sudden increase of voltage/current. Moreover, PRL will become open when it experiences significant over-current, thus protecting the circuit from overheating.

 

Low Thermal EMF (Electromotive Force)

PL and PRL series exhibit very low thermal EMF between electrodes, resistor and other metal structures. Low thermal EMF guarantees accurate and stable current measurement.

 

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 Featured Products

Part Number		Description	Data Sheet	App. Notes
RL/PRL Series of Chip Resistors		Low Resistance Value Chip Resistors with Long-side Electrodes for High Precision Current Detection

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