ADS7805UB Equivalent & Substitute Parts

Part Overview

The ADS7805UB is a 16-bit Analog-to-Digital Converter (ADC) manufactured by Texas Instruments, configured as a single-input SAR (Successive Approximation Register) architecture device in 28-SOIC surface mount packaging. This component operates with 100k samples per second and supports both external and internal voltage references at 5V supply levels. The ADS7805UB is classified as Last Time Buy, indicating end-of-life status. Equivalent and substitute parts are necessary to ensure design continuity, maintain supply chain reliability, and support long-term product availability for applications requiring 16-bit data acquisition functionality.

Key Parameters

Parameter	Value
Resolution	16 Bits
Sampling Rate	100k Samples/Second
Number of Inputs	1
Input Type	Single Ended
Data Interface	Parallel
Architecture	SAR
Reference Type	External, Internal
Analog Supply Voltage	5V
Digital Supply Voltage	5V
Operating Temperature Range	-25°C to 85°C
Package	28-SOIC
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the ADS7805UB are grouped based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are: 16-bit resolution, single input channel, SAR architecture, 5V analog and digital supply voltages, external and internal reference support, and 28-SOIC packaging. Substitutes are categorized into two groups:

Group 1: Direct Package & Interface Equivalents (28-SOIC, Parallel Interface) Parts maintaining identical packaging, parallel data interface, and core electrical specifications. These include AD976 series devices (AD976ABRZ, AD976ABRZRL, AD976BRZ, AD976BRZRL, AD976CRZ) and LTC1605 series devices (LTC1605ACSW#PBF, LTC1605ACSW#TRPBF, LTC1605AISW#PBF). Sampling rates within this group range from 100k to 200k samples per second, maintaining functional compatibility for applications not requiring higher throughput.

Group 2: Enhanced Performance Alternative (16-TSSOP, SPI Interface) The ADS8685IPWR represents an upgraded alternative with higher sampling rate (500k samples/second), SPI interface, programmable gain amplifier (PGA), and extended digital supply voltage range (1.65V to 5.25V). This device requires interface redesign but offers superior performance characteristics.

Group 3: Intermediate Performance Option (28-SOIC, Parallel Interface) The ADS8505IBDW provides 250k sampling rate with parallel interface retention, representing a performance step between the original ADS7805UB and the ADS8685IPWR.

Parameter Comparison

Part Number	Manufacturer	Resolution (Bits)	Sampling Rate (kS/s)	Inputs	Input Type	Data Interface	Package	Analog Supply	Digital Supply	Temp Range	Product Status
ADS7805UB	Texas Instruments	16	100	1	Single Ended	Parallel	28-SOIC	5V	5V	-25 to 85°C	Last Time Buy
ADS8505IBDW	Texas Instruments	16	250	1	Single Ended	Parallel	28-SOIC	5V	5V	-40 to 85°C	Active
ADS8685IPWR	Texas Instruments	16	500	1	Pseudo-Differential, Single Ended	SPI	16-TSSOP	5V	1.65 to 5.25V	-40 to 125°C	Active
AD976ABRZ	Analog Devices Inc.	16	200	1	Single Ended	Parallel	28-SOIC	5V	5V	-40 to 85°C	Active
AD976ABRZRL	Analog Devices Inc.	16	200	1	Single Ended	Parallel	28-SOIC	5V	5V	-40 to 85°C	Active
AD976BRZ	Analog Devices Inc.	16	100	1	Single Ended	Parallel	28-SOIC	5V	5V	-40 to 85°C	Active
AD976BRZRL	Analog Devices Inc.	16	100	1	Single Ended	Parallel	28-SOIC	5V	5V	-40 to 85°C	Active
AD976CRZ	Analog Devices Inc.	16	100	1	Single Ended	Parallel	28-SOIC	5V	5V	-40 to 85°C	Active
LTC1605ACSW#PBF	Analog Devices Inc.	16	100	1	Single Ended	Parallel	28-SOIC	5V	5V	0 to 70°C	Active
LTC1605ACSW#TRPBF	Analog Devices Inc.	16	100	1	Single Ended	Parallel	28-SOIC	5V	5V	0 to 70°C	Active
LTC1605AISW#PBF	Analog Devices Inc.	16	100	1	Single Ended	Parallel	28-SOIC	5V	5V	-40 to 85°C	Active

Engineering Selection Recommendations

For Direct Replacement (No Design Changes Required)

Select from the AD976 series (AD976BRZ, AD976BRZRL, AD976CRZ) or LTC1605AISW#PBF for applications requiring identical 100k sampling rate, parallel interface, and 28-SOIC packaging. These parts maintain full electrical and mechanical compatibility with the ADS7805UB. AD976 series devices from Analog Devices Inc. are Active status with extended temperature range (-40 to 85°C) compared to the original part. LTC1605AISW#PBF also supports the extended temperature range and offers unlimited moisture sensitivity level (MSL 1).

For Increased Sampling Rate (Parallel Interface Retained)

The ADS8505IBDW provides 250k sampling rate while maintaining parallel data interface and 28-SOIC packaging. This Texas Instruments device is Active status and suitable for applications requiring higher throughput without interface redesign. Operating temperature range extends to -40 to 85°C.

For Maximum Performance (Interface Redesign Required)

The ADS8685IPWR offers 500k sampling rate, programmable gain amplifier, and extended digital supply voltage range (1.65V to 5.25V). This device requires SPI interface implementation and uses 16-TSSOP packaging. It is recommended only for new designs or significant redesign efforts where the performance benefits justify interface changes. Operating temperature range extends to -40 to 125°C.

All recommended substitutes maintain ROHS3 compliance and REACH unaffected status consistent with the original ADS7805UB.

Frequently Asked Questions (FAQ)

Q: Can I directly replace ADS7805UB with any AD976 variant without PCB modifications?

A: Yes. AD976BRZ, AD976BRZRL, and AD976CRZ are direct replacements. All three maintain 28-SOIC packaging, parallel data interface, single-ended input configuration, and 5V supply requirements. The primary difference is packaging format (Tube vs. Tape & Reel). Verify your assembly process compatibility with the selected packaging option.

Q: What is the difference between LTC1605ACSW#PBF and LTC1605ACSW#TRPBF?

A: Both parts are electrically identical 16-bit, 100k sampling rate ADCs in 28-SOIC packaging. The difference is packaging format: LTC1605ACSW#PBF is supplied in Tube, while LTC1605ACSW#TRPBF is supplied in Tape & Reel (TR). Select based on your assembly equipment and volume requirements.

Q: Why does LTC1605ACSW#PBF have a narrower operating temperature range (0 to 70°C) compared to ADS7805UB (-25 to 85°C)?

A: The LTC1605ACSW#PBF is specified for commercial temperature range. If your application requires the extended temperature range of the original ADS7805UB, select LTC1605AISW#PBF instead, which operates from -40 to 85°C.

Q: Can I use ADS8685IPWR as a drop-in replacement?

A: No. The ADS8685IPWR requires design changes: it uses SPI interface instead of parallel, 16-TSSOP packaging instead of 28-SOIC, and supports pseudo-differential inputs in addition to single-ended. This part is suitable only for new designs or significant redesigns where higher sampling rate (500k vs. 100k) justifies the interface changes.

Q: What does "Last Time Buy" status mean for ADS7805UB?

A: Last Time Buy indicates the manufacturer has discontinued this part and will not produce additional units beyond a final order window. Existing inventory is available, but long-term supply is not guaranteed. Substitution to Active status parts (AD976 series, LTC1605 series, ADS8505IBDW, or ADS8685IPWR) is recommended for new designs or long-term product support.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance and REACH unaffected status, consistent with the original ADS7805UB.

Q: Which substitute offers the best balance between compatibility and performance?

A: The ADS8505IBDW provides optimal balance: it maintains 28-SOIC packaging and parallel interface (no design changes), increases sampling rate to 250k (2.5x improvement), and is Active status from Texas Instruments. This part is suitable for applications requiring performance improvement without significant redesign effort.

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