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UC3845NG4 Equivalent & Substitute Parts
Part Overview
The UC3845NG4 is a Power Supply Controller PWM Controller manufactured by Texas Instruments in 8-PDIP packaging. This device functions as a multi-topology regulator controller for boost, flyback, and step-up/step-down DC-DC converter applications. The UC3845NG4 is discontinued at DiGi Electronics, making equivalent and substitute parts necessary for ongoing design support and production requirements. Substitute parts must maintain compatibility across electrical parameters, package form factor, and functional topology support.
Substiute Parts
Key Parameters
| Parameter | UC3845NG4 Specification |
|---|---|
| Manufacturer | Texas Instruments |
| Category | Power Management (PMIC) |
| Package / Case | 8-DIP (0.300", 7.62mm) |
| Mounting Type | Through Hole |
| Voltage - Supply | 12V ~ 28V |
| Current - Supply | 11 mA |
| Operating Temperature | 0°C ~ 70°C (TA) |
| Output Type | Transistor Driver |
| Frequency - Switching | Up to 500kHz |
| Duty Cycle (Max) | 48% |
| RoHS Status | ROHS3 Compliant |
| Product Status | Discontinued at DiGi Electronics |
Substitute Part Grouping Explanation
Substitute parts for the UC3845NG4 are classified based on the following substitution criteria:
Primary Compatibility Parameters:
- Package / Case: 8-DIP (0.300", 7.62mm) form factor
- Mounting Type: Through Hole
- Output Type: Transistor Driver
- Frequency - Switching: Up to 500kHz
- Duty Cycle (Max): 48%
- Control Features: Frequency Control
- Topology Support: Boost, Flyback, Step-Up/Step-Down configurations
Voltage Supply Range Compatibility:
- UC3845NG4 operates at 12V ~ 28V supply voltage
- Substitute parts with 7.6V ~ 30V supply range encompass the original specification
- Substitute parts with 10V ~ 30V supply range require verification for 12V minimum operation
Temperature Rating Considerations:
- UC3845NG4 operates 0°C ~ 70°C (TA)
- Extended temperature variants (-40°C ~ 150°C) provide enhanced thermal performance
- Commercial temperature range (-25°C ~ 85°C) suitable for standard industrial applications
Parameter Comparison
| Part Number | Manufacturer | Package | Voltage - Supply (Vcc/Vdd) | Frequency - Switching | Duty Cycle (Max) | Operating Temperature | RoHS Status | Product Status |
|---|---|---|---|---|---|---|---|---|
| UC3845NG4 | Texas Instruments | 8-DIP (0.300", 7.62mm) | 12V ~ 28V | Up to 500kHz | 48% | 0°C ~ 70°C (TA) | ROHS3 Compliant | Discontinued at DiGi Electronics |
| UC3845N | onsemi | 8-DIP (0.300", 7.62mm) | 7.6V ~ 30V | Up to 500kHz | 48% | 0°C ~ 70°C (TA) | RoHS non-compliant | Obsolete |
| UC3844N | onsemi | 8-DIP (0.300", 7.62mm) | 10V ~ 30V | Up to 500kHz | 48% | 0°C ~ 70°C (TA) | RoHS non-compliant | Obsolete |
| UC3844AM | Microchip Technology | 8-DIP (0.300", 7.62mm) | 10V ~ 30V | Up to 500kHz | 48% | 0°C ~ 70°C (TA) | ROHS3 Compliant | Discontinued at DiGi Electronics |
| UC3844BN | STMicroelectronics | 8-DIP (0.300", 7.62mm) | 10V ~ 30V | Up to 500kHz | 48% | 0°C ~ 70°C (TJ) | ROHS3 Compliant | Active |
| UC3845BN | STMicroelectronics | 8-DIP (0.300", 7.62mm) | 7.6V ~ 30V | Up to 500kHz | 48% | -40°C ~ 150°C (TJ) | ROHS3 Compliant | Active |
| SG2844M | Microchip Technology | 8-DIP (0.300", 7.62mm) | 10V ~ 30V | 100Hz ~ 500kHz | 48% | -25°C ~ 85°C (TA) | ROHS3 Compliant | Discontinued at DiGi Electronics |
| UC2844BN | STMicroelectronics | 8-DIP (0.300", 7.62mm) | 10V ~ 30V | Up to 500kHz | 48% | -25°C ~ 85°C (TA) | ROHS3 Compliant | Active |
| UC2845BN | STMicroelectronics | 8-DIP (0.300", 7.62mm) | 7.6V ~ 30V | Up to 500kHz | 48% | -40°C ~ 150°C (TJ) | ROHS3 Compliant | Active |
| SG3844M | Microchip Technology | 8-DIP (0.300", 7.62mm) | 10V ~ 30V | 100Hz ~ 500kHz | 48% | 0°C ~ 70°C (TA) | ROHS3 Compliant | Discontinued at DiGi Electronics |
| UC3845BNG | onsemi | 8-DIP (0.300", 7.62mm) | 7.6V ~ 30V | Up to 500kHz | 48% | 0°C ~ 70°C (TA) | ROHS3 Compliant | Active |
Engineering Selection Recommendations
Primary Recommendation: UC3845BN (STMicroelectronics)
UC3845BN is the optimal substitute for UC3845NG4. Both parts share the UC3845 base product number, ensuring functional equivalence. UC3845BN maintains ROHS3 compliance matching the original specification and is currently in active production status with 88,791 units in stock. The supply voltage range of 7.6V ~ 30V encompasses the original 12V ~ 28V specification. Extended operating temperature range (-40°C ~ 150°C) provides superior thermal performance compared to the original 0°C ~ 70°C rating.
Secondary Recommendation: UC3845BNG (onsemi)
UC3845BNG provides direct manufacturer equivalence as an onsemi variant of the UC3845 controller. ROHS3 compliance and active product status ensure long-term availability. Supply voltage range of 7.6V ~ 30V covers the original specification. Operating temperature range of 0°C ~ 70°C matches the original UC3845NG4 exactly. Inventory of 2,500 units supports production requirements.
Alternative Recommendation: UC2845BN (STMicroelectronics)
UC2845BN functions as a compatible alternative with identical electrical parameters to UC3845BN. The UC2844/UC2845 series provides equivalent performance in boost and flyback topologies. ROHS3 compliance and active production status ensure availability. Extended temperature range (-40°C ~ 150°C) exceeds original specifications. Inventory of 1,925 units available.
Compliance-Based Selection: UC3844BN (STMicroelectronics)
UC3844BN serves as a substitute for applications requiring active production status and ROHS3 compliance. Supply voltage range of 10V ~ 30V requires verification for 12V minimum operation in the original design. Active product status with 2,530 units in stock ensures long-term supply chain stability.
Not Recommended: onsemi UC3845N and UC3844N
Both onsemi parts are classified as obsolete with RoHS non-compliant status, making them unsuitable for new designs or production requiring regulatory compliance.
Frequently Asked Questions (FAQ)
Q: Can UC3845BN directly replace UC3845NG4 without circuit modifications?
A: Yes. UC3845BN shares the UC3845 base product number and maintains identical electrical parameters including supply voltage range (7.6V ~ 30V encompasses 12V ~ 28V), switching frequency (up to 500kHz), duty cycle (48%), and 8-DIP package form factor. Both are ROHS3 compliant. No circuit modifications are required.
Q: What is the difference between UC3845 and UC3844 controllers?
A: Both UC3845 and UC3844 are PWM controllers supporting boost, flyback, and step-up/step-down topologies with identical switching frequency (up to 500kHz) and duty cycle (48%). The primary difference is the supply voltage range: UC3845 operates at 7.6V ~ 30V while UC3844 operates at 10V ~ 30V. For applications requiring 12V ~ 28V operation, both are suitable, though UC3845 provides lower voltage headroom.
Q: Why is UC3845BN recommended over UC3845NG4?
A: UC3845NG4 is discontinued at DiGi Electronics, creating supply chain risk. UC3845BN is in active production with 88,791 units in stock, ensuring long-term availability. Both maintain ROHS3 compliance and identical functional specifications. UC3845BN offers extended operating temperature range (-40°C ~ 150°C) compared to the original 0°C ~ 70°C.
Q: Are SG2844M and SG3844M suitable substitutes?
A: SG2844M and SG3844M are offline switch controllers with isolated output topology, differing functionally from the UC3845NG4 non-isolated controller architecture. While both support 100Hz ~ 500kHz switching frequency and 48% duty cycle in 8-DIP packaging, the isolated output configuration and different control topology make them unsuitable for direct substitution in non-isolated boost and flyback applications.
Q: What is the impact of supply voltage range differences?
A: UC3845NG4 operates at 12V ~ 28V. Substitute parts with 7.6V ~ 30V range (UC3845BN, UC3845BNG, UC2845BN) fully encompass this specification. Substitute parts with 10V ~ 30V range (UC3844N, UC3844AM, UC3844BN, SG2844M, SG3844M) require verification that the design does not operate below 10V. For 12V ~ 28V applications, both ranges are compatible.
Q: Does operating temperature range affect substitution compatibility?
A: Operating temperature range does not prevent substitution. UC3845NG4 operates at 0°C ~ 70°C. Substitute parts with extended ranges (-40°C ~ 150°C or -25°C ~ 85°C) provide enhanced thermal performance and are fully compatible. Substitute parts with identical 0°C ~ 70°C range (UC3845BNG, SG3844M) match the original specification exactly.
Q: Is RoHS compliance a critical factor for substitution?
A: Yes. UC3845NG4 is ROHS3 compliant. For regulatory compliance and long-term production support, substitute parts must maintain ROHS3 compliance. UC3845BN, UC3844BN, UC3844AM, UC2844BN, UC2845BN, SG2844M, SG3844M, and UC3845BNG all meet ROHS3 requirements. onsemi UC3845N and UC3844N are RoHS non-compliant and unsuitable for compliant designs.
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