UC2845BD1 STMicroelectronics Integrated Circuit (Small Outline Packages) In Stock
STMicroelectronics UC2845BD1 is a current-mode PWM controller for boost and flyback converters, supplying up to 1 A gate drive at switching frequencies up to 500 kHz, operating from 8.2 V to 30 V in an 8-pin SOIC package. Available from authorized distributors with worldwide shipping.
- Manufacturer
- STMicroelectronics
- Package
- Small Outline Packages
- Pin Count
- 8
- Lifecycle
- ACTIVE
- Datasheet
- UC2845BD1 Datasheet PDF
- Category
- Integrated Circuit
- Price
- From $0.4540(MOQ 98)
- Temp Range
- -25.0°C to 85.0°C
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
What are the key features of UC2845BD1?
- Current-mode PWM control with cycle-by-cycle peak current limiting provides inherent overcurrent protection and simplifies loop compensation in flyback and boost SMPS designs
- Up to 500 kHz switching frequency enables compact transformer and inductor design, reducing magnetic component size and overall converter footprint
- 1 A totem-pole gate-drive output directly drives a power MOSFET without an external gate driver buffer stage, lowering BOM count
- 8.2 V UVLO with hysteresis and 30 V maximum input prevents operation below safe supply rails, protecting the converter during startup and supply droops
What is UC2845BD1 used for?
The UC2845BD1 is widely used in industrial and telecom flyback power supplies where its current-mode PWM control, 1 A gate drive, and 500 kHz capability enable compact, high-efficiency offline AC/DC converters from 15 W to 150 W. It suits boost PFC pre-regulators and battery-charger front-ends that require tight output regulation and fast transient response through peak-current feedback. Designers also apply it in auxiliary power supplies for motor drives and UPS systems where the 8.2 V to 30 V bias input can be derived from a bootstrap winding on the main transformer.
What are the specifications of UC2845BD1?
| Factory Lead Time | 14Weeks |
| YTEOL | 7 |
| Analog IC - Other Type | SWITCHING CONTROLLER |
| Control Mode | CURRENT-MODE |
| Control Technique | PULSE WIDTH MODULATION |
| Input Voltage-Max | 30V |
| Input Voltage-Min | 8.2V |
| Input Voltage-Nom | 15V |
| JESD-30 Code | R-PDSO-G8 |
| JESD-609 Code | e3 |
| Number of Functions | 1 |
| Output Current-Max | 1A |
| Package Body Material | PLASTIC/EPOXY |
| Package Equivalence Code | SOP8,.25 |
| Package Shape | RECTANGULAR |
| Package Style | SMALL OUTLINE |
| Peak Reflow Temperature (Cel) | 260 |
| Qualification Status | Not Qualified |
| Surface Mount | YES |
| Switcher Configuration | SINGLE |
| Switching Frequency-Max | 500kHz |
| Technology | BIPOLAR |
| Temperature Grade | COMMERCIAL EXTENDED |
| Terminal Finish | Matte Tin (Sn) - annealed |
| Terminal Form | GULL WING |
| Terminal Pitch | 1.27mm |
| Terminal Position | DUAL |
| Time@Peak Reflow Temperature-Max (s) | 30 |
| ## UC2845BD1 Alternates Showing results | Image |
| Package | Small Outline Packages |
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
| Moisture Sensitivity Level | MSL 3 |
| ECCN | EAR99 |
| HTS Code | 8542.39.00.60 |
| Country of Origin | Morocco |
Where can I find the UC2845BD1 datasheet?
UC2845BD1 Datasheet DownloadOfficial datasheet from STMicroelectronics
What are equivalent replacements for UC2845BD1?
Compatible alternatives and drop-in replacements for UC2845BD1:
Switching Controller, Current-mode, 1A, 500kHz Switching Freq-Max, PDSO8
suggested
suggested
suggested
Frequently Asked Questions
What switching frequency range does the UC2845BD1 support, and how is it set by a resistor-capacitor network?
The UC2845BD1 oscillator frequency is set by an external timing resistor (RT) and capacitor (CT) connected between the RT/CT pin and ground. The switching frequency f = 1.72 / (RT × CT) with typical values of RT = 10 kΩ and CT = 330 pF yielding approximately 500 kHz. Reducing CT to 100 pF with the same resistor raises frequency to around 1.5 times, while increasing CT lowers it, allowing the designer to tune between roughly 20 kHz and 500 kHz.
How does the UC2845BD1 current-mode control simplify loop compensation compared to voltage-mode PWM controllers?
In current-mode control the inner current loop converts the inductor into a voltage-controlled current source, effectively removing one pole from the power stage transfer function. This reduces the output filter from a second-order LC response to a first-order capacitor-dominated response, allowing the outer voltage compensation network to use a single-pole type-II compensator with a single resistor-capacitor network rather than the two-zero type-III compensator typically required for voltage-mode flyback designs at the same 500 kHz switching frequency.
What is the gate-drive output current of the UC2845BD1, and can it directly drive a 3 nF power MOSFET gate at 500 kHz?
The UC2845BD1 provides a 1 A peak totem-pole gate-drive output capable of charging and discharging a 3 nF MOSFET gate capacitance. At 500 kHz each switching period is 2 µs; the 1 A driver can charge 3 nF from 0 V to 12 V in approximately 36 ns, which is well within one period, so direct drive of medium-power MOSFETs up to approximately 5 nF Ciss is feasible without an external gate driver at frequencies up to 500 kHz.
At what input voltage does the UC2845BD1 UVLO circuit enable operation, and why is the hysteresis important for flyback converter startup?
The UC2845BD1 enables its PWM output when VCC rises above 8.2 V (turn-on threshold) and shuts down if VCC falls below 7.6 V (turn-off threshold), providing 0.6 V of hysteresis. In a flyback converter the VCC rail is bootstrapped from an auxiliary winding; during startup the input bulk capacitor charges the auxiliary winding through a startup resistor. The 0.6 V hysteresis prevents the controller from cycling on and off rapidly (hiccup mode) if the auxiliary supply droops slightly under load, ensuring clean single-pulse startup rather than multiple restart attempts.
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About STMicroelectronics
STMicroelectronics is a global semiconductor leader serving customers across the spectrum of electronics applications. ST's products are found in a wide range of applications including automotive, industrial, personal electronics, and communications.
| Qty. | Unit Price | Ext. Price |
|---|---|---|
| 98+ | $0.8399 | $82.31 |
| 100+ | $0.6600 | $66.00 |
| 250+ | $0.6300 | $157.50 |
| 500+ | $0.6100 | $305.00 |
| 1000+ | $0.4710 | $471.00 |
| 2000+ | $0.4540 | $908.00 |
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