Alpha SM Series

Alpha SM Series

The SM transfer moulded ultra-precision resistor 1-2-3 network series from Alpha Electronics offers a 3 terminal, 2 element resistor network in a small through-hole package. Each resistive element can range from 10Ω up to 30kΩ all with tight tolerances down to +0.02% absolute and +0.01% matching (50Ω to 30kΩ). By utilising Alpha's Bulk Metal® foil resistor technology, they are able to produce this resistor network series with low temperature coefficients (both absolute and tracking) as well as excellent long-term stability. The Alpha SM series offers three pins with a standard pin pitch of 2.54 ±0.25mm.

  • 2 element resistor network
  • Each resistor element is available in any resistance between 50Ω and 30kΩ
  • Through-hole conformally coated 3 pin package
  • Tight absolute tolerance of ±0.02% for resistances between 100Ω and 30kΩ with an even tighter matching tolerance of ±0.01% over the same resistance range available
  • Tight absolute TCR of ±2.5 ppm/°C (from -55°C up to +125°C)
  • Tight tracking TCR available of between ±0.5 ppm/°C and ±3 ppm/°C depending on resistance ratio between the two elements
  • Power rating of 0.3W per resistor package(at +125°C)
  • Maximum rated operating temperature +125°C
  • Working temperature from -65°C up to +150°C

The SM through-hole, ultra-precision resistor 1-2-3 network series exhibits excellent high frequency characteristics thanks to Alpha's Bulk Metal® foil resistor technology, making them suitable for the most demanding precision applications.

Alpha's SM resistor network series are ideal for use in input and feedback resistors for amplifiers due to both the input and feedback resistors being incorporated into the same package, therefore amplification is not affected by temperature change.

The below table gives the full specifications for each resistor model available including the Alpha SM series:

Alpha SM Specifications

* Symbols parenthesized are for part number composition
** Please contact us for resistance availability
TCR is from -25°C to +125°C for SLD Type

Table 1
Specifications
Additional Features
  • 2 element resistor network
  • Utilises Alpha's Bulk Metal® foil technology for ultra-precision
  • Moulded through-hole resistor 1-2-3 network (1 package, 2 resistive elements, 3 pin layout)
  • Pin pitch is 2.54 ±0.25mm
  • Working temperature range of -65°C to +150°C
  • Maximum rated operating temperature of +125°C
Maximum Power Rating
  • 0.3W for the full resistor package (at +125°C)
Maximum Resistance
  • 30kΩ per resistive element
Minimum Resistance
  • 50Ω per resistive element
TCRAbsolute TCR:
  • ±5 ppm/°C (X))
  • ±2.5 ppm/°C (Y)
TCR Tracking:
  • ±0.5 ppm/°C (Resistance Ratio = 1)
  • ±1 ppm/°C (1 < Resistance Ratio ≤ 10)
  • ±2 ppm/°C (10 < Resistance Ratio ≤ 100)
  • ±3 ppm/°C (100 < Resistance Ratio)
ToleranceAbsolute:
  • ±0.02% (Q)
  • ±0.05% (A)
  • ±0.1% (B)
Matching:
  • ±0.01% (T)
  • ±0.02% (Q)
  • ±0.05% (A)
  • ±0.1% (B)

We are pleased to provide you with a range of additional content including videos, product datasheets, case studies, white papers and application notes for your reference. Please see below for the latest content available:

 

 

DOCUMENTATION
PDF DocumentAlpha Electronics SLD and SM ultra-precision 1-2-3 network resistor series datasheet
PDF DocumentAlpha Electronics ultra-precision resistor network circuit layouts, number of possible elements per layout and TCR information
PDF DocumentAlpha Electronics manufacturing process, adjustment of resistance value construction, and temperature characteristics of resistance information which covers their resistor range including typical characteristics such as their typical 0.14 ppm/°C TCR
PDF DocumentAlpha Electronics additional services and custom products available to compliment their precision and ultra-precision resistor ranges
PDF DocumentAlpha Electronics ultra-precision resistors databook, covering all parts and models they have to offer

 

 

 

VIDEOS
Resistor Stability Put to the Test (Demo Video)

In this video, host Richard Zuratt from VPG puts the stability of the three major resistor technologies — foil, thin, and thick film — to the test. Each resistor type is subjected to an overload pulse and its change in resistance value is recorded. Due to the homogeneous nature of the VPG Bulk Metal® Foil resistor, it is the only of the three to experience no change from the high power pulse. This demonstrated performance makes foil resistors the technology of choice for critical applications where long-term stability and survivability are paramount.
A head to head comparison of the survival rates of precision thin film nichrome (NiCr) resistors versus VFR Bulk Metal Foil resistors in a high humidity environment.

All resistors that are based on nichrome, which is a category that includes both thin film devices and Bulk Metal Foil resistors, are susceptible to electro-chemical corrosion or etching when placed in a high humidity environment and powered with a very low wattage. But since the nichrome element of a Bulk Metal Foil resistor is hundreds of times thicker than the element in a thin film device with the same value, it will last much longer under these conditions. This video shows the actual etching process and survival times for thin film and foil nichrome resistive elements as they are tested in 100% humidity conditions.
Comparison Testing of Chip Resistor Technologies Under High Vibration

Surface-mount resistors suffer physical stresses when exposed to high vibration or thermally unstable environments. Failure modes commonly occur in welds, solder joints, connectors, and terminations, ultimately resulting in circuit failure. In this demonstration, vibration-table-mounted boards are subjected to ±2° deflection 25 times per second and monitored for any ΔR > 0.1%. All the chip resistors failed in 2 to 12 minutes (8K to 16K cycles). But the Alpha MPP molded Bulk Metal® Z-Foil resistor with flexible terminations experienced over a million cycles with no change in resistance.
VIDEOS
Resistor Stability Put to the Test (Demo Video)

In this video, host Richard Zuratt from VPG puts the stability of the three major resistor technologies — foil, thin, and thick film — to the test. Each resistor type is subjected to an overload pulse and its change in resistance value is recorded. Due to the homogeneous nature of the VPG Bulk Metal® Foil resistor, it is the only of the three to experience no change from the high power pulse. This demonstrated performance makes foil resistors the technology of choice for critical applications where long-term stability and survivability are paramount.
A head to head comparison of the survival rates of precision thin film nichrome (NiCr) resistors versus VFR Bulk Metal Foil resistors in a high humidity environment.

All resistors that are based on nichrome, which is a category that includes both thin film devices and Bulk Metal Foil resistors, are susceptible to electro-chemical corrosion or etching when placed in a high humidity environment and powered with a very low wattage. But since the nichrome element of a Bulk Metal Foil resistor is hundreds of times thicker than the element in a thin film device with the same value, it will last much longer under these conditions. This video shows the actual etching process and survival times for thin film and foil nichrome resistive elements as they are tested in 100% humidity conditions.
Comparison Testing of Chip Resistor Technologies Under High Vibration

Surface-mount resistors suffer physical stresses when exposed to high vibration or thermally unstable environments. Failure modes commonly occur in welds, solder joints, connectors, and terminations, ultimately resulting in circuit failure. In this demonstration, vibration-table-mounted boards are subjected to ±2° deflection 25 times per second and monitored for any ΔR > 0.1%. All the chip resistors failed in 2 to 12 minutes (8K to 16K cycles). But the Alpha MPP molded Bulk Metal® Z-Foil resistor with flexible terminations experienced over a million cycles with no change in resistance.

This product is available fully compliant to the RoHS EU directive 2011/65/EU.

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