ADS7809UB Equivalent & Substitute Parts

Part Overview

The ADS7809UB is a 16-bit Analog to Digital Converter manufactured by Texas Instruments, configured as a single-channel SAR (Successive Approximation Register) ADC with 1:1 sample-and-hold to ADC ratio. The device operates at 100k samples per second with external or internal reference capability, housed in a 20-SOIC surface mount package. Currently in Last Time Buy status, alternative components are necessary for new designs and long-term availability assurance.

Key Parameters

Parameter	Value
Resolution	16 Bit
Sampling Rate	100k SPS
Number of Inputs	1
Input Type	Single Ended
Architecture	SAR
Data Interface	SPI, DSP
Reference Type	External, Internal
Analog Supply Voltage	5V
Digital Supply Voltage	5V
Operating Temperature Range	-40°C ~ 85°C
Package	20-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the ADS7809UB is determined by the following critical parameters: 16-bit resolution, single-channel input configuration, SAR architecture, SPI data interface compatibility, 5V analog and digital supply operation, and -40°C to 85°C operating temperature range. Package compatibility (20-SOIC form factor) is required for direct board-level replacement without layout modification.

The substitute parts are grouped into two categories:

Direct Package Substitutes (20-SOIC): Parts maintaining identical or superior electrical performance within the same physical footprint, enabling direct PCB replacement.

Functional Equivalents with Package Variation: Parts meeting core electrical specifications but in alternative packages, requiring board redesign or adapter solutions.

Parameter Comparison

Parameter	ADS7809UB	ADS8509IBDW	ADS8685IPWR	AD977ABRZ	AD977BRZ	AD977BRZRL
Manufacturer	Texas Instruments	Texas Instruments	Texas Instruments	Analog Devices Inc.	Analog Devices Inc.	Analog Devices Inc.
Resolution (Bits)	16	16	16	16	16	16
Sampling Rate (SPS)	100k	250k	500k	200k	100k	100k
Number of Inputs	1	1	1	1	1	1
Input Type	Single Ended	Single Ended	Pseudo-Differential, Single Ended	Single Ended	Single Ended	Single Ended
Architecture	SAR	SAR	SAR	SAR	SAR	SAR
Data Interface	SPI, DSP	SPI	SPI	SPI	SPI	SPI
Reference Type	External, Internal	External, Internal	External, Internal	External, Internal	External, Internal	External, Internal
Analog Supply (V)	5V	5V	5V	5V	5V	5V
Digital Supply (V)	5V	5V	1.65V ~ 5.25V	5V	5V	5V
Operating Temperature (°C)	-40 ~ 85	-40 ~ 85	-40 ~ 125	-40 ~ 85	-40 ~ 85	-40 ~ 85
Package	20-SOIC	20-SOIC	16-TSSOP	20-SOIC	20-SOIC	20-SOIC
Product Status	Last Time Buy	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	3 (168 Hours)	2 (1 Year)	3 (168 Hours)	3 (168 Hours)	3 (168 Hours)	3 (168 Hours)

Engineering Selection Recommendations

ADS8509IBDW is the primary direct replacement for the ADS7809UB. Both devices share identical 20-SOIC packaging, 16-bit resolution, single-channel single-ended input configuration, and 5V supply requirements. The ADS8509IBDW operates at 250k SPS, exceeding the ADS7809UB's 100k SPS specification while maintaining backward compatibility. Active product status and improved MSL rating (2 vs. 3) provide superior long-term availability and handling characteristics. SPI interface compatibility is confirmed; DSP interface support is not required for this substitute.

AD977BRZ and AD977BRZRL provide equivalent performance at identical 100k SPS sampling rate with matching 20-SOIC package geometry. Both are manufactured by Analog Devices Inc. and maintain full electrical compatibility with 16-bit resolution, single-channel single-ended input, and 5V supply operation. AD977BRZRL is supplied in Tape & Reel packaging, while AD977BRZ is supplied in Tube packaging. Both devices are in Active product status.

AD977ABRZ operates at 200k SPS, providing higher sampling rate performance than the ADS7809UB while maintaining 20-SOIC package compatibility and all core electrical specifications. Active product status supports long-term design continuity.

ADS8685IPWR is a functional equivalent with enhanced specifications including 500k SPS sampling rate, extended operating temperature range (-40°C to 125°C), and programmable gain amplifier (PGA) integration. However, this device is packaged in 16-TSSOP form factor, requiring PCB layout redesign and is not suitable for direct board-level replacement. Selection of this part is appropriate only when higher sampling rates, extended temperature operation, or PGA functionality are required by the application.

All substitute parts maintain ROHS3 compliance and EAR99 export classification consistent with the ADS7809UB.

Frequently Asked Questions (FAQ)

Q: Can ADS8509IBDW directly replace ADS7809UB on existing PCBs?

A: Yes. Both devices use identical 20-SOIC packaging with matching pin assignments for core functions. The ADS8509IBDW's higher 250k SPS sampling rate is backward compatible with applications designed for 100k SPS operation.

Q: What is the key difference between AD977BRZ and AD977BRZRL?

A: Both parts are electrically identical 16-bit 100k SPS ADCs in 20-SOIC packages. The primary difference is packaging format: AD977BRZ is supplied in Tube packaging, while AD977BRZRL is supplied in Tape & Reel format. Selection depends on assembly line requirements and volume handling procedures.

Q: Why is ADS8685IPWR listed as a substitute if it uses a different package?

A: ADS8685IPWR meets all core electrical requirements (16-bit resolution, single-channel input, SAR architecture, SPI interface, 5V analog supply) and exceeds performance specifications with 500k SPS sampling rate and extended temperature range. It is classified as a functional equivalent for applications where package redesign is acceptable and enhanced performance is beneficial.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts (ADS8509IBDW, ADS8685IPWR, AD977ABRZ, AD977BRZ, AD977BRZRL) maintain ROHS3 compliance consistent with the ADS7809UB.

Q: What is the MSL (Moisture Sensitivity Level) significance for these parts?

A: MSL rating indicates maximum storage time at specified humidity before baking is required. ADS8509IBDW has MSL 2 (1 Year), providing superior moisture tolerance compared to ADS7809UB and other substitutes rated MSL 3 (168 Hours). Lower MSL ratings reduce handling and storage complexity for high-volume manufacturing environments.

Q: Can I use AD977ABRZ if my application requires 100k SPS operation?

A: Yes. AD977ABRZ operates at 200k SPS, which exceeds the 100k SPS requirement. The higher sampling rate is backward compatible with applications designed for lower sampling rates. No firmware or software modifications are required.

Q: Is DSP interface support critical for substitute selection?

A: The ADS7809UB supports both SPI and DSP interfaces. All listed substitutes support SPI interface. If DSP interface is required by your application, verify interface compatibility with your specific system architecture before selection.

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