Siemens Hall sensor ICs
Siemens produced a range of different Hall effect sensor ICs. These appear to be the Hall sensors used in RAFI switches, before RAFI started using HFO Hall ICs instead. As RAFI RS 74 C was introduced around 1975, that suggests that at least part of this range was in production at that time.
Wolfram Zucker in Germany provided some photographs of various Siemens Bauteile Service price list pages. Having now been able to identify the origin of the PDF in the Documentation section—and along with it, a description of its contents—we now also have the dates of the details it contains. From this, we get the first indications of the product history:
- In February 1977, the Hall types are SAS 201 S2 and S4, SAS 211 S2 and S4, and SAS 221 S2 and S4.
- In October 1977, SAS 251 is listed as a new product.
- The product range remained unchanged in April 1978.
- By October 1981, SAS 231 W, SAS 241 and SAS 261 had been introduced (between 1978 and 1981). SAS 261 is reported as being marked as requiring export permission. SAS 201–221 are no longer listed.
- The 1982/1983 databook lists SAS 241 and 241 S4; SAS 250; SAS 251, 251 S4 and 251 S5; SAS 261 and 261 S4; and SAS 231 L and W.
- In April 1983, the product range is SAS 231 W, SAS 241, SAS 250, SAS 251 and SAS 261. SAS 250 is marked as new, and the export permission restriction for SAS 261 is gone.
- In April 1985, only SAS 231 W and SAS 251 are listed in the price list
- In the 1985/1986 databook, SAS 231 W and L, SAS 241 and 241 S5, SAS 250 and SAS 261 and 261 S4 are marked “Nicht für Neuentwicklung” (not for new development) and appear to be nearing end of life at that point. Only SAS 251, 251 S4 and 251 S5 are still considered production types.
It seems that Siemens had discontinued most of the range by 1985, including the types with enable input that RAFI were using. Some of the models seem to have had very short production lives. This may indicate why RAFI switched over to using HFO’s products instead. Wolfram conjectures that the S-variants represent items that do not meet the required tolerances, and are downgraded to lower-specification products rather than be discarded; this may relate to the coloured-stripe markings and why they are always accept a lower supply voltage than the non-S base model. This may also indicate why, from SAS 231 onwards, the S-variants are not given in the price lists. Unfortunately, Siemens practice seems to have been inconsistent and there is no definitive pattern to the markings.
The following table lists all known types. The Documented column lists the range of years within which each type has been found in Siemens literature. It does not indicate when each type entered production or was discontinued; ranges are used only to conserve column space. Years marked with an asterisk (*) indicate products not intended for new development (products that will be ending production).
|Model||Type||Terminals||Temperature range||Supply voltage||Marking||Documented|
|SAS 201 S2||Digital, dynamic||VCC, GND, dual outputs||Not yet known||1977, 1978|
|SAS 201 S4|
|SAS 211 S2||Digital, static|
|SAS 211 S4|
|SAS 221 S2||Digital, unspecified||VCC, GND, Q and Q̅ outputs|
|SAS 221 S4|
|SAS 231 W||Linear, bipolar||VCC, GND, zero point, sensitivity, output, unused||0–70 °C||4.75–15 V||None||1981–1985*|
|SAS 231 L||Linear, bipolar (MIKROPACK)||Blue/green||1982, 1985*|
|SAS 241||Digital, dynamic, open collector, bipolar||VCC, GND, dual outputs||0–70 °C||4.75–18 V||SAS 241||1981–1983, 1985*|
|SAS 241 S4||4.75–5.25 V||White||1982, 1985*|
|SAS 250||Digital, static, open collector, bipolar||−40–125 °C||4.5–27 V||SAS 250||1982, 1983, 1985*|
|SAS 251||0–70 °C||4.75–27 V||SAS 251||1977–1985|
|SAS 251 S4||4.75–5.25 V||SAS 251 S4||1982|
|SAS 251 S5||4.75–18 V||Orange||1982|
|SAS 261||VCC, GND, enable input, output||0–70 °C||4.75–18 V||Blue||1981, 1982, 1985*|
|SAS 261 S4||4.75–5.25 V||Green||1982, 1985*|
Most types use the same IC package, 10 mm wide, 6.5 mm tall and 2.1 mm deep. SAS 201 has 0.3 mm extra leg length, with four terminals. SAS 231 has six terminals instead of four, and uses two separate form factors: a miniature 3.9 × 4 × 2 mm package, and a MIKROPACK version. Most if not all models are bipolar: they are switched on by the south pole, and then switched off by the north pole. (Unipolar Hall sensors simply detect the presence of the south pole.)
Some SAS ICs are marked by nothing other than a line drawn across the front, without branding or any mention of the model number or production date. The colour of the line indicates the model. OleVoip’s lone RS 76 C switch has such a sensor, marked with merely an orange stripe. This indicates that it is SAS 251 S5. Wolfram Zucker has a collection of Siemens Hall ICs for sale; he has helpfully posted photos on his analog ICs page of various SAS types, and although most are blank or marked normally, some SAS 261 chips are marked with only a blue stripe, which is the expected colour from the catalogue.
Some models were copied by VEB Halbleiterwerk Frankfurt (Oder):
|Siemens model||Signals||Supply voltage||HFO model|
|SAS 251||Dual in-phase outputs||4.75–27 V||B 451 G|
|SAS 251 S4||4.75–5.25 V||B 453 G|
|SAS 251 S5||4.75–18 V||B 452 G|
|SAS 261||Single output, enable input||4.75–18 V||B 462 G|
|SAS 261 S4||4.75–5.25 V||B 461 G|
In 2013, Christoph Kessler produced a PDF containing portions of three Siemens documents:
- Page 1: Schwerpunkttypen Siemens Bauteile Service Preis- und Lagerlist Februar 1977 page 39, Digitale Sonderbausteine (SAS 201–221)
- Pages 2–3: Siemens Bauteile Service Schwerpunkttypen Preis- und Lagerlist April 1983 pages 11.10 and 11.11, Magnetisch gesteurte IS (HKZ 101, SAS 231–261)
- Pages 4–18: Integrierte Schaltungen für Industrielle Anwendungen 1982/83 pages 419–433 (SAS 231–261)
This shows up on other sites, and it seemed impossible to find where it originated. Now that the source is known, it remains archived here.
- Siemens Hall effect sensor ICs (archive of Christoph Kessler’s scans)
- Siemens Integrierte Schaltungen für Industrielle Anwendungen Datenbuch 1985/1986 pp. 542-553 (Integrated Circuits for Industrial Applications; from scans from Wolfram Zucker)