UC3844D8 Equivalent & Substitute Parts

Part Overview

The UC3844D8 is a Power Supply Controller PWM Controller manufactured by Texas Instruments in 8-SOIC surface mount packaging. This current mode PWM control IC is designed for power supply applications requiring step-up, step-down, or isolated topologies. The part is currently active in production with 100,198 units in stock. Equivalent and substitute parts are necessary when the primary part becomes unavailable, when alternative manufacturers offer improved specifications, or when design requirements necessitate enhanced performance characteristics such as extended temperature ranges or higher switching frequencies.

Key Parameters

Parameter	UC3844D8 (Main Part)
Manufacturer	Texas Instruments
Base Product Number	UC3844
Package / Case	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Voltage - Supply	12V ~ 28V
Current - Supply	11 mA
Operating Temperature	0°C ~ 70°C (TA)
Product Status	Active
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the UC3844D8 are grouped based on the following critical parameters that determine functional compatibility:

Primary Substitution Criteria:

Package / Case: 8-SOIC (0.154", 3.90mm Width) — all substitutes maintain identical physical footprint
Mounting Type: Surface Mount — all substitutes use surface mount technology
Base Product Number Family: UC3844, UC3845, UC2844 series — functionally related PWM controller architectures
Output Type: Transistor Driver — consistent control output configuration
Topology Support: Boost, Flyback, and related DC-DC converter topologies
RoHS Compliance: ROHS3 Compliant — environmental regulatory alignment

Secondary Compatibility Parameters:

Voltage - Supply (Vcc/Vdd): Range overlap with UC3844D8 (12V ~ 28V)
Frequency - Switching: Up to 500kHz capability
Duty Cycle (Max): 48% standard specification
Control Features: Frequency Control capability
Moisture Sensitivity Level (MSL): 1 (Unlimited) preferred for handling consistency

Substitutes are classified as Direct Manufacturer Parts (pin-compatible, same base series), MFR Recommended Parts (enhanced specifications within same family), or Upgrade Parts (improved performance characteristics with extended temperature or frequency ranges).

Parameter Comparison

Part Number	Manufacturer	Base Product	Package	Voltage - Supply (Vcc/Vdd)	Frequency - Switching	Duty Cycle (Max)	Operating Temperature	Product Status	RoHS Status	Inventory
UC3844D8	Texas Instruments	UC3844	8-SOIC	12V ~ 28V	—	—	0°C ~ 70°C (TA)	Active	ROHS3	100,198
UC3844AD8TR	Unitrode	UC3844	8-SOIC	—	—	—	0°C ~ 70°C (TA)	Active	—	2,200
UC3844BD1013TR	STMicroelectronics	UC3844	8-SOIC	10V ~ 30V	Up to 500kHz	48%	0°C ~ 70°C (TJ)	Active	ROHS3	2,150
UC3845ADM-TR	Microchip Technology	UC3845	8-SOIC	7.6V ~ 30V	Up to 500kHz	48%	0°C ~ 70°C (TA)	Discontinued at DiGi Electronics	RoHS	1,200
UC3845BD1013TR	STMicroelectronics	UC3845	8-SOIC	7.6V ~ 30V	Up to 500kHz	48%	-40°C ~ 150°C (TJ)	Active	ROHS3	287,800
UC3845BD1G	onsemi	UC3845	8-SOIC	7.6V ~ 30V	Up to 500kHz	48%	0°C ~ 70°C (TA)	Active	ROHS3	2,900
UC3845BD1R2G	onsemi	UC3845	8-SOIC	7.6V ~ 30V	Up to 500kHz	48%	0°C ~ 70°C (TA)	Active	ROHS3	88,972
UC3845BVD1R2G	onsemi	UC3845	8-SOIC	7.6V ~ 30V	Up to 500kHz	48%	-40°C ~ 105°C (TA)	Active	ROHS3	4,091
UC2844BD1	STMicroelectronics	UC2844	8-SOIC	10V ~ 30V	Up to 500kHz	48%	-25°C ~ 85°C (TA)	Active	ROHS3	3,100
UC2844BD1013TR	STMicroelectronics	UC2844	8-SOIC	10V ~ 30V	Up to 500kHz	48%	-25°C ~ 85°C (TA)	Active	ROHS3	55,864
ISL6843IBZ-T	Renesas Electronics Corporation	ISL6843	8-SOIC	9V ~ 16V	Up to 2MHz	96%	-40°C ~ 105°C (TA)	Active	ROHS3	17,700

Engineering Selection Recommendations

Direct Substitutes (UC3844 Series): UC3844AD8TR (Unitrode) and UC3844BD1013TR (STMicroelectronics) maintain the UC3844 base product number and are functionally equivalent to the UC3844D8. Both are Active products with ROHS3 compliance. UC3844BD1013TR provides extended electrical specifications (10V ~ 30V supply range, 500kHz switching frequency capability) compared to the main part's 12V ~ 28V range.

Compatible Alternatives (UC3845 Series): UC3845 variants from STMicroelectronics, onsemi, and Microchip Technology are pin-compatible substitutes with enhanced supply voltage range (7.6V ~ 30V). UC3845BD1013TR (STMicroelectronics) offers extended operating temperature range (-40°C ~ 150°C) suitable for industrial applications. UC3845BD1R2G and UC3845BD1G (onsemi) provide high inventory availability (88,972 and 2,900 units respectively) with standard 0°C ~ 70°C temperature range. UC3845ADM-TR (Microchip) is discontinued at DiGi Electronics and should be avoided for new designs.

Extended Temperature Alternatives (UC2844 Series): UC2844BD1 and UC2844BD1013TR (STMicroelectronics) are upgrade options with extended operating temperature range (-25°C ~ 85°C) and 10V ~ 30V supply voltage capability. Both maintain 500kHz switching frequency and 48% duty cycle specifications. These are suitable for applications requiring wider temperature operation than the UC3844D8's 0°C ~ 70°C range.

High-Performance Alternative (ISL6843 Series): ISL6843IBZ-T (Renesas Electronics Corporation) represents a performance upgrade with synchronous rectifier capability, up to 2MHz switching frequency, and 96% maximum duty cycle. Supply voltage range is 9V ~ 16V with -40°C ~ 105°C operating temperature. This part is suitable for applications requiring higher switching frequencies and improved efficiency but operates within a narrower supply voltage window.

All recommended substitutes maintain 8-SOIC surface mount packaging, ROHS3 compliance, and MSL 1 or MSL 3 moisture sensitivity ratings suitable for standard handling procedures.

Frequently Asked Questions (FAQ)

Q: Can UC3845 series parts directly replace UC3844D8 in existing designs? A: UC3845 variants are pin-compatible with UC3844D8 and share the same 8-SOIC package. However, verify that your application's supply voltage range (UC3845 supports 7.6V ~ 30V versus UC3844D8's 12V ~ 28V) and temperature requirements align with the selected substitute. Electrical characteristics and control loop behavior may differ; circuit validation is necessary.

Q: What is the difference between UC3844, UC3845, and UC2844 base product numbers? A: All three are current mode PWM controller families within the UCx84x series. UC3844 and UC3845 operate at 0°C ~ 70°C (standard temperature), while UC2844 extends to -25°C ~ 85°C. UC3845 supports wider supply voltage range (7.6V ~ 30V) compared to UC3844 (12V ~ 28V). Selection depends on application temperature and voltage requirements.

Q: Is ISL6843IBZ-T a suitable replacement for UC3844D8? A: ISL6843IBZ-T is functionally similar but operates within a narrower supply voltage range (9V ~ 16V) and offers enhanced performance with synchronous rectifier capability and up to 2MHz switching frequency. It is suitable only if your application operates within the 9V ~ 16V supply window and benefits from higher switching frequency operation.

Q: What packaging options are available for UC3844D8 substitutes? A: All listed substitutes maintain the 8-SOIC (0.154", 3.90mm Width) surface mount package. Packaging variants differ in tape format: Cut Tape (CT) & Digi-Reel®, Tube, or Tape & Reel (TR). These are handling and delivery format differences only; the component footprint and pinout remain identical.

Q: Are all substitute parts ROHS3 compliant? A: All active substitute parts listed are ROHS3 compliant except UC3845ADM-TR (Microchip), which carries RoHS compliance without the "3" designation. UC3844AD8TR (Unitrode) does not specify RoHS status in available data. For applications requiring ROHS3 certification, select from STMicroelectronics, onsemi, or Renesas alternatives.

Q: Which substitute offers the best inventory availability? A: UC3845BD1013TR (STMicroelectronics) provides the highest inventory with 287,800 units in stock, followed by UC3845BD1R2G (onsemi) with 88,972 units. Both are Active products with ROHS3 compliance and identical electrical specifications.

Q: What is the operating temperature range difference between UC3844D8 and extended-range alternatives? A: UC3844D8 operates 0°C ~ 70°C. UC3845BD1013TR extends to -40°C ~ 150°C, UC3845BVD1R2G to -40°C ~ 105°C, and UC2844 variants to -25°C ~ 85°C. Select extended-range parts only if your application requires operation outside the 0°C ~ 70°C window.

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