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DS1621S/T&R Equivalent & Substitute Parts
Part Overview
The DS1621S/T&R is a digital temperature sensor manufactured by Analog Devices Inc./Maxim Integrated, designed for local temperature measurement across the -55°C to 125°C range with 9-bit resolution and I2C output. The device is packaged in 8-SOIC surface mount configuration and operates on 2.7V to 5.5V supply voltage.
This part is classified as obsolete. Equivalent and substitute parts are necessary to ensure design continuity, maintain supply chain reliability, and access components with improved specifications or active product status.
Substiute Parts
Key Parameters
| Parameter | DS1621S/T&R |
|---|---|
| Sensor Type | Digital, Local |
| Sensing Temperature Range | -55°C ~ 125°C |
| Output Type | I2C |
| Voltage Supply | 2.7V ~ 5.5V |
| Resolution | 9 bits |
| Accuracy | ±0.5°C (0°C ~ 70°C), ±2°C (-55°C ~ 125°C) |
| Package | 8-SOIC (0.154", 3.90mm Width) |
| Mounting Type | Surface Mount |
| Product Status | Obsolete |
| RoHS Status | RoHS non-compliant |
Substitute Part Grouping Explanation
Substitution eligibility is determined by the following critical parameters:
- Package compatibility: 8-SOIC form factor (0.154", 3.90mm Width)
- Operating temperature range: Minimum -55°C to 125°C coverage
- Supply voltage: 2.7V to 5.5V operation
- Output protocol: I2C or SMBus compatibility
- Mounting type: Surface mount
Substitute parts are grouped into three categories:
Direct Equivalent (Same Packaging Format): DS1621S+T&R maintains identical electrical and mechanical specifications with active product status and improved RoHS compliance.
Upgrade Options (Enhanced Specifications): TMP275AIDR, ADT75ARZ-REEL, AT30TS74-SS8M-T, and AT30TS75A-SS8M-T provide higher resolution, improved accuracy, or extended feature sets while maintaining package compatibility and temperature range coverage.
Alternative Options (Compatible Parameters): AT30TS750A-SS8M-B and other listed parts meet core electrical requirements and package specifications with variations in resolution, accuracy, or feature availability.
Parameter Comparison
| Part Number | Manufacturer | Temperature Range | Resolution | Output Type | Supply Voltage | Accuracy | Package | Product Status | RoHS Status |
|---|---|---|---|---|---|---|---|---|---|
| DS1621S/T&R | Analog Devices Inc./Maxim Integrated | -55°C ~ 125°C | 9 b | I2C | 2.7V ~ 5.5V | ±0.5°C / ±2°C | 8-SOIC | Obsolete | Non-compliant |
| DS1621S+T&R | Analog Devices Inc./Maxim Integrated | -55°C ~ 125°C | 9 b | I2C | 2.7V ~ 5.5V | ±0.5°C / ±2°C | 8-SOIC | Active | ROHS3 Compliant |
| TMP275AIDR | Texas Instruments | -55°C ~ 127°C | 11 b | SMBus | 2.7V ~ 5.5V | ±0.5°C / ±1.5°C | 8-SOIC | Active | ROHS3 Compliant |
| ADT75ARZ-REEL | Analog Devices Inc. | -55°C ~ 125°C | 12 b | I2C/SMBus | 2.7V ~ 5.5V | ±2°C / ±3°C | 8-SOIC | Active | ROHS3 Compliant |
| AT30TS74-SS8M-T | Microchip Technology | -55°C ~ 125°C | 11 b | I2C/SMBus | 1.7V ~ 5.5V | ±2°C / ±3°C | 8-SOIC | Active | ROHS3 Compliant |
| AT30TS75A-SS8M-T | Microchip Technology | -55°C ~ 125°C | 11 b | I2C/SMBus | 1.7V ~ 5.5V | ±1°C / ±3°C | 8-SOIC | Active | ROHS3 Compliant |
| AT30TS750A-SS8M-B | Microchip Technology | -55°C ~ 125°C | 11 b | I2C/SMBus | 1.7V ~ 5.5V | ±1°C / ±3°C | 8-SOIC | Active | ROHS3 Compliant |
| ADT75ARZ-REEL7 | Analog Devices Inc. | -55°C ~ 125°C | 12 b | I2C/SMBus | 2.7V ~ 5.5V | ±2°C / ±3°C | 8-SOIC | Active | ROHS3 Compliant |
Engineering Selection Recommendations
For Direct Replacement: DS1621S+T&R is the primary equivalent, offering identical electrical specifications with active product status and ROHS3 compliance. This part requires no design modification and provides improved supply chain availability.
For Enhanced Resolution and Accuracy: TMP275AIDR delivers 11-bit resolution with ±0.5°C accuracy in the 0°C to 70°C range, extending the upper operating temperature to 127°C. SMBus compatibility maintains protocol-level interoperability with I2C systems. ROHS3 compliance and active status support long-term availability.
For Higher Resolution with Extended Features: ADT75ARZ-REEL and ADT75ARZ-REEL7 provide 12-bit resolution with I2C/SMBus dual protocol support. Both maintain the -55°C to 125°C temperature range and 2.7V to 5.5V supply voltage. Active product status and ROHS3 compliance ensure regulatory alignment.
For Lower Supply Voltage Operation: AT30TS74-SS8M-T, AT30TS75A-SS8M-T, and AT30TS750A-SS8M-B operate from 1.7V minimum supply voltage, enabling single-cell battery applications. All three maintain 8-SOIC packaging and -55°C to 125°C temperature coverage. AT30TS75A-SS8M-T and AT30TS750A-SS8M-B offer ±1°C accuracy in the 0°C to 85°C range.
All substitute parts are ROHS3 compliant with active product status, ensuring regulatory compliance and supply chain continuity.
Frequently Asked Questions (FAQ)
Q: Can DS1621S/T&R be replaced with DS1621S+T&R without design changes?
A: Yes. DS1621S+T&R is a direct equivalent with identical electrical specifications, package, and pinout. The primary difference is active product status and improved RoHS compliance. No firmware or hardware modifications are required.
Q: What is the key difference between I2C and SMBus output types for substitution purposes?
A: SMBus is a subset of I2C protocol with stricter timing and voltage specifications. Devices with SMBus output (TMP275AIDR, ADT75ARZ-REEL, AT30TS74-SS8M-T) are compatible with I2C host systems. However, verify host controller support for SMBus-specific features if used.
Q: Does higher resolution (11-bit or 12-bit) require firmware changes?
A: Resolution differences affect data format and conversion time. Firmware must be updated to interpret the additional bits. Verify host software compatibility with the selected part's resolution before implementation.
Q: Are all substitute parts available in the same packaging format?
A: All listed substitutes use 8-SOIC (0.154", 3.90mm Width) surface mount packaging, maintaining PCB layout compatibility. Verify tape & reel (TR) or cut tape (CT) availability based on production volume requirements.
Q: Which substitute offers the best accuracy for precision temperature measurement?
A: AT30TS75A-SS8M-T and AT30TS750A-SS8M-B provide ±1°C accuracy in the 0°C to 85°C range. TMP275AIDR delivers ±0.5°C accuracy in the 0°C to 70°C range. Selection depends on the required temperature measurement window.
Q: Can I use a substitute with lower minimum supply voltage (1.7V vs. 2.7V)?
A: Yes. Parts with 1.7V minimum supply voltage (AT30TS74-SS8M-T, AT30TS75A-SS8M-T, AT30TS750A-SS8M-B) are backward compatible with 2.7V to 5.5V systems. This provides design flexibility for future low-power applications.
Q: What is the impact of product status (Active vs. Obsolete) on long-term availability?
A: Active products have manufacturer commitment to continued production and support. Obsolete products face potential discontinuation and supply constraints. For new designs or long-term production, select active status parts to ensure supply chain reliability.
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