TL594CD Equivalent & Substitute Parts

Part Overview

The TL594CD is a Buck, Push-Pull Regulator DC-DC Controller IC manufactured by onsemi in 16-SOIC packaging. This device functions as a transistor driver for step-down and step-up/step-down topologies with positive output configuration. The TL594CD is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain compatibility across supply voltage range, output configuration, package form factor, and control feature set.

Key Parameters

Parameter	TL594CD Value
Manufacturer	onsemi
Package / Case	16-SOIC (0.154", 3.90mm Width)
Output Type	Transistor Driver
Function	Step-Down, Step-Up/Step-Down
Output Configuration	Positive
Topology	Buck, Push-Pull
Number of Outputs	2
Voltage - Supply (Vcc/Vdd)	7V ~ 40V
Frequency - Switching	300kHz
Duty Cycle (Max)	96%
Synchronous Rectifier	Yes
Control Features	Dead Time Control, Frequency Control
Operating Temperature	-40°C ~ 85°C (TA)
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: 16-SOIC form factor required
Output type: Transistor driver configuration
Output configuration: Positive output only
Supply voltage range: 7V ~ 40V minimum requirement
Control features: Dead time control and frequency control capability
Number of outputs: 2-output configuration
Mounting type: Surface mount

Substitute parts are grouped into two categories based on functional scope and product status:

Category A - Direct Functional Equivalents (Active Status): Parts with identical or expanded topology support, active product status, and RoHS3 compliance. These include TL494CDR, TL494ID, TL494IDR, TL594CDR, TL594ID, and TL594IDR from Texas Instruments.

Category B - Functional Alternatives (Obsolete Status): Parts with matching topology and control features but obsolete status. This includes TL494CD from onsemi.

Category C - Limited Scope Alternatives: Parts with restricted topology support or fixed output specifications. This includes AZ494CMTR-E1 from Diodes Incorporated, which supports only buck topology with fixed 5V output.

Parameter Comparison

Parameter	TL594CD	TL494CDR	TL494ID	TL494IDR	TL594CDR	TL594ID	TL594IDR	TL494CD	AZ494CMTR-E1
Manufacturer	onsemi	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments	onsemi	Diodes Incorporated
Package / Case	16-SOIC	16-SOIC	16-SOIC	16-SOIC	16-SOIC	16-SOIC	16-SOIC	16-SOIC	16-SOIC
Output Type	Transistor Driver	Transistor Driver	Transistor Driver	Transistor Driver	Transistor Driver	Transistor Driver	Transistor Driver	Transistor Driver	Fixed
Function	Step-Down, Step-Up/Step-Down	Step-Up, Step-Down, Step-Up/Step-Down	Step-Up, Step-Down, Step-Up/Step-Down	Step-Up, Step-Down, Step-Up/Step-Down	Step-Up, Step-Down, Step-Up/Step-Down	Step-Up, Step-Down, Step-Up/Step-Down	Step-Up, Step-Down, Step-Up/Step-Down	Step-Down, Step-Up/Step-Down	Step-Down
Output Configuration	Positive	Positive	Positive	Positive	Positive	Positive	Positive	Positive	Positive
Topology	Buck, Push-Pull	Buck, Boost, Flyback, Forward Converter, Full-Bridge, Half-Bridge, Push-Pull	Buck, Boost, Flyback, Forward Converter, Full-Bridge, Half-Bridge, Push-Pull	Buck, Boost, Flyback, Forward Converter, Full-Bridge, Half-Bridge, Push-Pull	Buck, Boost, Flyback, Forward Converter, Full-Bridge, Half-Bridge, Push-Pull	Buck, Boost, Flyback, Forward Converter, Full-Bridge, Half-Bridge, Push-Pull	Buck, Boost, Flyback, Forward Converter, Full-Bridge, Half-Bridge, Push-Pull	Buck, Push-Pull	Buck
Number of Outputs	2	2	2	2	2	2	2	2	2
Voltage - Supply (Vcc/Vdd)	7V ~ 40V	7V ~ 40V	7V ~ 40V	7V ~ 40V	7V ~ 40V	7V ~ 40V	7V ~ 40V	7V ~ 40V	7V ~ 36V
Frequency - Switching	300kHz	1kHz ~ 300kHz	1kHz ~ 300kHz	1kHz ~ 300kHz	1kHz ~ 300kHz	1kHz ~ 300kHz	1kHz ~ 300kHz	200kHz	40kHz
Duty Cycle (Max)	96%	45%	45%	45%	97%	97%	97%	48%	N/A
Synchronous Rectifier	Yes	No	No	No	No	No	No	Yes	No
Control Features	Dead Time Control, Frequency Control	Dead Time Control, Frequency Control	Dead Time Control, Frequency Control	Dead Time Control, Frequency Control	Dead Time Control, Frequency Control	Dead Time Control, Frequency Control	Dead Time Control, Frequency Control	Dead Time Control, Frequency Control	N/A
Operating Temperature	-40°C ~ 85°C	0°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C	0°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C	0°C ~ 70°C	-40°C ~ 85°C
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Obsolete	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitutes (Recommended for New Designs):

TL494IDR and TL494CDR from Texas Instruments are the preferred substitutes. Both parts maintain the 16-SOIC package, transistor driver output type, positive output configuration, and required control features. These parts are active products with ROHS3 compliance. TL494IDR supports the full operating temperature range (-40°C ~ 85°C) matching the original TL594CD specification. The expanded topology support (Buck, Boost, Flyback, Forward Converter, Full-Bridge, Half-Bridge, Push-Pull) provides design flexibility beyond the original part's Buck and Push-Pull limitation.

TL594CDR and TL594IDR from Texas Instruments offer identical base product number alignment with higher maximum duty cycle (97% vs 96%), supporting the same expanded topology set. TL594IDR maintains the full temperature range (-40°C ~ 85°C). Both are active products with ROHS3 compliance.

Secondary Substitutes (Functional Alternatives):

TL494CD from onsemi maintains manufacturer continuity and identical topology support to the original TL594CD. However, this part is also obsolete and does not provide a long-term solution. Operating temperature range is restricted to 0°C ~ 70°C, and RoHS compliance status is non-compliant.

Limited Scope Alternative:

AZ494CMTR-E1 from Diodes Incorporated is suitable only for applications requiring fixed 5V output with buck topology exclusively. This part is not recommended as a general substitute due to restricted topology support and fixed output specification. It is appropriate only for specific 5V buck regulator applications.

Frequently Asked Questions (FAQ)

Q: Can TL494CDR directly replace TL594CD in existing designs?

A: Yes, TL494CDR is a direct functional substitute. Both parts share the 16-SOIC package, transistor driver output type, positive output configuration, and control features (dead time control, frequency control). TL494CDR is an active product with ROHS3 compliance, addressing the obsolescence of TL594CD. The expanded topology support in TL494CDR does not create compatibility issues in designs using only Buck and Push-Pull topologies.

Q: What is the difference between TL494 and TL594 base product numbers?

A: Both TL494 and TL594 are DC-DC controller ICs in 16-SOIC packaging with transistor driver outputs and positive output configuration. The primary differences are in maximum duty cycle (TL594 series: 96-97% vs TL494 series: 45%) and synchronous rectifier support (TL594CD includes synchronous rectifier; TL494 variants do not). For applications not requiring high duty cycle operation, TL494 variants provide equivalent functionality with better availability and active product status.

Q: Is the AZ494CMTR-E1 suitable as a general replacement?

A: No. AZ494CMTR-E1 is not a general substitute for TL594CD. This part is a fixed 5V buck regulator with 200mA output current, designed for specific low-power applications. It lacks the programmable output voltage, frequency control, and multi-topology support of the TL594CD. Use AZ494CMTR-E1 only in applications requiring fixed 5V buck regulation.

Q: What are the temperature range implications when selecting a substitute?

A: TL594CD operates across -40°C ~ 85°C. Substitutes with restricted temperature ranges (0°C ~ 70°C) such as TL494CD and TL594CDR are not suitable for applications requiring full temperature coverage. For designs requiring -40°C ~ 85°C operation, select TL494IDR, TL494ID, TL594IDR, or TL594ID.

Q: Does RoHS compliance affect substitution decisions?

A: Yes. TL594CD is RoHS non-compliant. For new designs subject to RoHS3 requirements, select ROHS3-compliant substitutes: TL494CDR, TL494ID, TL494IDR, TL594CDR, TL594ID, TL594IDR, or AZ494CMTR-E1. For legacy designs without RoHS requirements, non-compliant parts remain functionally equivalent.

Q: Can I use TL594IDR in place of TL594CD?

A: Yes. TL594IDR is a direct substitute with identical base product number, same 16-SOIC package, and matching control features. TL594IDR is an active product with ROHS3 compliance and supports the full -40°C ~ 85°C operating temperature range. The primary difference is packaging format (Cut Tape & Digi-Reel vs standard packaging).

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