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STMicroelectronics UC2842BD1
- Part No.:
- UC2842BD1
- Manufacturer:
- STMicroelectronics
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
UC2842BD1.pdf
- Description:
- IC REG CTRLR BST FLYBK ISO 8-SO
- Quantity:
- Payment:
- Shipping:
Inventory:741
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Product details
Overview
UC2842BD1 from STMicroelectronics is a high-performance current-mode PWM controller IC designed for fixed-frequency off-line and DC-DC power supplies. It features a trimmed oscillator (guaranteed 250 kHz), latching PWM for cycle-by-cycle current limiting, internal 5 V reference with ±1% accuracy, under-voltage lockout (UVLO) with 16 V turn-on/10 V turn-off thresholds, and a totem-pole output capable of ±1 A peak drive current for N-channel MOSFETs.
For engineers reviewing the UC2842BD1 datasheet, UC2842BD1 pinout, UC2842BD1 application, or UC2842BD1 equivalent, key selection considerations include its 94–100% maximum duty cycle capability, 0.5 mA start-up current, 2.5 V error amplifier input reference, 3 V supply voltage rejection on current sense, and SO8 package compatibility with legacy Minidip footprints.
Technical Context
The UC2842BD1 implements current-mode control using an internal error amplifier, PWM latch, and comparator that compares sensed inductor current against the error amp output. Its oscillator uses RT/CT programming with discharge current trimming (7.5–8.8 mA), enabling precise frequency control up to 500 kHz and automatic feed-forward compensation via the current-sense path.
UVLO hysteresis ensures reliable start-up and brown-out recovery, while the totem-pole output stage provides fast rise/fall times (50–150 ns into 1 nF) and rail-to-rail swing (13.5 V high / 0.4 V low at 20 mA), optimized for driving power MOSFET gates directly without external buffers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 250 kHz guaranteed at 25°C; programmable up to 500 kHz via RT/CT network |
| Max Duty Cycle | 94–100% - enables high-efficiency flyback and forward converters with minimal dead time |
| UVLO Threshold | 16 V (on) / 10 V (off) - ensures stable operation across wide AC line ranges in off-line SMPS |
| Reference Voltage | 5.00 V ±1% - precision internal bandgap reference for feedback loop stability and accuracy |
| Output Drive | ±1 A peak sink/source - directly drives gate capacitance of medium-power MOSFETs (e.g., < 10 nF) |
| Start-up Current | < 0.5 mA at 6.5 V - minimizes auxiliary winding losses and enables low-power standby designs |
| Error Amp GBW | 0.7–1 MHz - supports stable Type II/III compensation for current-mode topologies |
Pinout & Package
UC2842BD1 is housed in an industry-standard SO8 package (5.0 mm × 6.2 mm, 1.27 mm pitch), pin-compatible with Minidip variants and widely supported by PCB design libraries.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - COMP | Error amplifier output | Provides access to EA output for external Type II/III compensation network placement |
| 2 - VFB | Inverting input of error amplifier | Connects to resistor divider from output rail; sets regulation point via 2.5 V internal reference |
| 3 - ISENSE | Current sense comparator input | Accepts voltage from shunt/resistor; trips PWM latch when ≥1.0 V (±10%) to limit peak inductor current |
| 4 - RT/CT | Oscillator timing node | RT to VREF + CT to GND sets fOSC; discharge current (7.5–8.8 mA) defines timing slope and frequency accuracy |
| 5 - GROUND | Signal and power ground | Single-point return for control circuitry and current-sense reference; critical for noise immunity |
| 6 - OUTPUT | PWM output driver | Totem-pole stage sinks/sources up to 1 A; logic-high = MOSFET ON; low impedance in OFF state |
| 7 - VCC | Supply input | Operates from 10–30 V; UVLO protects during brown-out; internal zener clamps at 36 V max |
| 8 - VREF | 5 V reference output | Supplies stable 5 V @ ≤20 mA; sources RT current and can bias external circuitry (e.g., optocoupler LED) |
Key Features
| Feature | Design Value |
|---|---|
| Latching PWM with cycle-by-cycle current limit | Prevents transformer saturation and MOSFET overcurrent during fault conditions without external protection |
| Internally trimmed 5 V reference (±1%) | Eliminates need for external reference IC; reduces BOM count and improves load regulation (±25 mV) |
| Automatic feed-forward compensation | Uses sensed current ramp to cancel input line variations - simplifies loop design and improves transient response |
| Low start-up current (< 0.5 mA) | Enables direct startup from high-impedance auxiliary windings, reducing standby power in no-load conditions |
| High-current totem-pole output (±1 A) | Drives MOSFET gates up to ~10 nF directly - avoids gate driver ICs and associated layout complexity |
Applications
| AC-DC Adapter | Flyback SMPS |
|---|---|
|
Use Scenario: 12 V/2 A universal-input wall adapter for consumer electronics. IC Role / Device Role / Timing Role: Primary-side PWM controller implementing current-mode flyback regulation with fixed 250 kHz switching. Use Value: UVLO hysteresis prevents erratic restart during brown-out; 5 V reference enables accurate secondary-side feedback via optocoupler. |
Use Scenario: Isolated 5 V/5 A offline power supply for industrial PLC I/O modules. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller managing primary-side MOSFET switching and overcurrent shutdown. Use Value: Latching PWM limits peak current per cycle, protecting transformer and MOSFET during short-circuit events. |
| DC-DC Boost Converter | Offline Forward Converter |
|
Use Scenario: 12 V to 24 V boost converter for automotive body control units. IC Role / Device Role / Timing Role: Regulates output voltage using current-mode control with external current sense resistor. Use Value: Feed-forward compensation maintains stable output despite wide input voltage range (9–16 V battery). |
Use Scenario: 48 V to 12 V forward converter in telecom power shelf. IC Role / Device Role / Timing Role: Primary-side controller synchronizing MOSFET gate drive and reset winding timing. Use Value: 100% duty cycle support enables optimal core utilization; totem-pole output drives high-side MOSFET directly. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar current-mode PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC3842BD1 | Commercial temperature range (0–70°C) vs. UC2842BD1's extended range (–25 to 85°C); identical electrical specs and pinout | Not rated for industrial ambient temperatures above 70°C; unsuitable for enclosed or high-temperature environments | Select UC3842BD1 only for cost-sensitive commercial-grade designs with controlled thermal environments |
| TL494CN | Voltage-mode (not current-mode); dual-output, adjustable dead time, built-in error amps - no integrated current sense comparator or UVLO | Requires external current sensing and protection logic; better suited for push-pull or half-bridge topologies than flyback | Choose TL494CN when dual-output phase control or flexible dead-time adjustment is required, not for direct UC2842BD1 replacement |
Compared with UC3842BD1 and TL494CN, UC2842BD1 uniquely combines extended temperature operation, integrated current-mode control, and low-startup-current UVLO-making it optimal for ruggedized flyback and forward converters where reliability and minimal external components are critical.
Availability
UC2842BD1 is available at Aetrix Electronics and suitable for AC-DC adapters, flyback SMPS, DC-DC boost converters, and offline forward converters requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for UC2842BD1 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, analog, microcontrollers, and automotive ICs.
The UCx84xB family was developed specifically for cost-effective, high-reliability current-mode switch-mode power supplies - targeting off-line and isolated DC-DC applications where precision timing, robust fault handling, and minimal external parts are essential.
FAQ
What is the maximum operating frequency of UC2842BD1?
The UC2842BD1 supports oscillator frequencies up to 500 kHz via external RT/CT programming. Its trimmed oscillator guarantees 250 kHz at 25°C, and the current-mode architecture remains stable across this full range. Operation beyond 500 kHz is not characterized and may compromise latch timing and current-sense accuracy.
Can UC2842BD1 drive a P-channel MOSFET directly?
No - UC2842BD1's OUTPUT pin is a totem-pole stage referenced to ground, sourcing current when high and sinking when low. It is designed to drive N-channel MOSFET gates (low-side or high-side with bootstrap). Driving a P-channel MOSFET directly would require inverted logic and level-shifting, which is unsupported and not recommended.
Does UC2842BD1 include soft-start functionality?
UC2842BD1 does not integrate soft-start, but Figure 24 in the datasheet shows a verified external soft-start circuit using a capacitor charged through a resistor into the COMP pin. This method controls ramp-up of the error amplifier output, limiting initial duty cycle and preventing inrush current.
How does the current sense threshold behave over temperature?
The current sense trip point is 1.0 V ±10% at 25°C and exhibits ±0.2 mV/°C drift, resulting in ≤ ±20 mV variation over –25°C to 85°C. This is confirmed in Figure 7 of the datasheet, showing Vth shifts less than 0.1 V across the full operating range - sufficient for most overload protection requirements.
UC2842BD1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Boost, Flyback
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 10V ~ 30V
- Frequency - Switching:
- Up to 500kHz
- Duty Cycle (Max):
- 96%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Frequency Control
- Operating Temperature:
- -25°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
UC2842BD1 FAQ
1.How can I place an order for UC2842BD1 through Aetrix?
Please submit a Request for Quotation (RFQ) for UC2842BD1 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for UC2842BD1 reliable?
The price and inventory of UC2842BD1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC2842BD1 is usually 5 days.
3.What payment methods are accepted for UC2842BD1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC2842BD1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC2842BD1?
UC2842BD1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC2842BD1 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for UC2842BD1?
For technical support, including UC2842BD1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC2842BD1 requirements.
6.How does Aetrix verify that UC2842BD1 is sourced from the original manufacturer or authorized distributors?
All UC2842BD1 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that UC2842BD1 meets industry standards.
7.What is the process for return or replacement of UC2842BD1?
All UC2842BD1 units undergo pre-shipment inspection (PSI). If there is an issue with UC2842BD1, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The UC2842BD1 part is unused and in its original packaging.
Return procedure for UC2842BD1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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