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STMicroelectronics E-UC3843BN
- Part No.:
- E-UC3843BN
- Manufacturer:
- STMicroelectronics
- Category:
- DC DC Switching Controllers
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
E-UC3843BN.pdf
- Description:
- IC REG CTRLR BST/FLYBK 8-MINIDIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,652
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Product details
Overview
E-UC3843BN from STMicroelectronics is a high-performance current-mode PWM controller IC designed for fixed-frequency DC-DC and off-line power supplies. It features a trimmed oscillator guaranteed at 250 kHz, under-voltage lockout with 8.5 V turn-on / 7.9 V turn-off thresholds, latching PWM for cycle-by-cycle current limiting, and a 5 V ±1% internal reference. It drives N-channel MOSFETs directly via a totem-pole output capable of ±1 A peak current, and supports duty cycles up to 100% in continuous conduction mode flyback or forward converters.
For engineers reviewing the E-UC3843BN datasheet, E-UC3843BN pinout, E-UC3843BN application, or E-UC3843BN equivalent, this device is selected for cost-sensitive, low-to-mid power AC-DC adapters, battery chargers, and industrial SMPS where precise current-mode control, low start-up current (<0.5 mA), and integrated UVLO hysteresis are critical.
Technical Context
The UC3843BN implements current-mode control using an internal error amplifier, PWM latch, and current-sense comparator that terminates switch conduction when sensed inductor current reaches the error amp output voltage. Its oscillator uses RT/CT programming with discharge current trimming (7.5–8.8 mA) to ensure frequency stability across temperature and supply voltage.
UVLO circuitry enables automatic restart after brownout recovery, while the 5 V reference provides stable biasing for external timing components and feedback dividers. The output stage operates in push-pull configuration with fast rise/fall times (50–150 ns into 1 nF), optimized for gate driving without external buffers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | Guaranteed 250 kHz at 25°C; programmable up to 500 kHz via RT/CT network for flexible switching speed selection. |
| UVLO Threshold | Turn-on at 8.5 V ±0.6 V, turn-off at 7.9 V ±0.6 V - ensures reliable startup in low-input-voltage applications like 12 V DC-DC systems. |
| Reference Voltage | 5.00 V ±10 mV at 1 mA load - provides accurate, temperature-stable bias for feedback networks and timing circuits. |
| Output Drive | ±1 A peak sink/source capability - directly drives medium-size N-MOSFET gates without external drivers in ≤60 W designs. |
| Current Sense Gain | 3.0 V/V ±5% - converts sense resistor voltage to precise comparator trip point for accurate peak-current limiting. |
| Start-up Current | <0.5 mA at 6.5 V - minimizes auxiliary winding losses and enables high-efficiency standby operation. |
| Max Duty Cycle | 96% typical - supports wide input range operation in flyback topologies with minimal dead time constraints. |
Pinout & Package
Package: 8-pin Mini-DIP (PDIP-8), body width 7.95–9.75 mm, lead pitch 2.54 mm, RoHS-compliant through-hole mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - COMP | Error amplifier output | Provides open-collector node for loop compensation; connects to RC network between pins 1 and 2 for Type II/III stability. |
| 2 - VFB | Inverting input of error amplifier | Receives feedback voltage from output divider; sets regulation point when COMP voltage equals 2.5 V reference. |
| 3 - ISENSE | Current sense comparator input | Accepts voltage from primary-side sense resistor; triggers PWM latch reset when ≥1.0 V (trip threshold). |
| 4 - RT/CT | Oscillator timing interface | RT connects to VREF (pin 8) and CT to GND (pin 5); sets fOSC and max duty cycle via discharge current and capacitor value. |
| 5 - GROUND | Signal and power ground reference | Single-point return for control logic, error amp, and oscillator - must be star-connected near input bulk capacitor. |
| 6 - OUTPUT | Totem-pole MOSFET gate driver | Sources/sinks up to 1 A; low-state voltage ≤0.4 V at 20 mA ensures full MOSFET turn-off in high-noise environments. |
| 7 - VCC | Supply input | Accepts 10–30 V DC; powers internal bias, reference, and logic; UVLO monitors this pin exclusively. |
| 8 - VREF | 5 V reference output | Supplies charging current for CT via RT; also used for optocoupler bias or auxiliary rail generation (≤20 mA load). |
Key Features
| Feature | Design Value |
|---|---|
| Latching PWM control | Ensures single-pulse-per-cycle operation during overcurrent events, preventing subharmonic oscillation in continuous conduction mode. |
| Internally trimmed 5 V reference | ±1% initial accuracy and <0.2 mV/°C drift enable stable regulation without external trimming resistors or calibration. |
| Low start-up current | <0.5 mA allows direct bootstrap from high-impedance auxiliary windings, reducing standby power in energy-efficient adapters. |
| Automatic feed-forward compensation | Input voltage variation directly modulates oscillator ramp slope, improving line transient response without extra components. |
| High-current totem-pole output | ±1 A drive strength eliminates need for discrete gate drivers in ≤100 kHz, ≤60 W flyback converters. |
Applications
| AC-DC Adapter | Battery Charger |
|---|---|
|
Use Scenario: 5–24 V output, universal input (85–265 VAC) wall adapter for consumer electronics. IC Role / Device Role / Timing Role: Primary-side PWM controller implementing discontinuous conduction mode (DCM) flyback with opto-coupled feedback. Use Value: UVLO hysteresis prevents chattering during brownouts; 250 kHz switching enables compact transformer and EMI filter design. |
Use Scenario: Constant-voltage/constant-current (CV/CC) lithium-ion charger for portable tools or power banks. IC Role / Device Role / Timing Role: Regulates both output voltage and charge current via dual-loop feedback (VFB + ISENSE). Use Value: Cycle-by-cycle current limiting protects battery during CC phase; 5 V reference stabilizes current-sense amplifier bias. |
| Industrial DC-DC Converter | LED Driver |
|
Use Scenario: 24 V input to isolated 5/12 V outputs for PLC I/O modules or sensor interfaces. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller in forward converter topology with synchronous rectification. Use Value: 100% duty cycle support accommodates wide input transients; low operating current (<17 mA) reduces thermal load in sealed enclosures. |
Use Scenario: Constant-current LED driver for signage or architectural lighting with dimming interface. IC Role / Device Role / Timing Role: Controls MOSFET switch in buck-derived topology; ISENSE pin monitors LED string current via shunt resistor. Use Value: Precise 3.0 V/V current sense gain enables ±3% LED current regulation; soft-start compatibility (via pin 1) prevents inrush stress. |
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 |
|---|---|---|---|
| UC3842BN | UVLO thresholds 16 V ON / 10 V OFF; higher start-up voltage requirement. | Better suited for universal AC-DC front-end designs with bulk capacitor >200 VDC. | Select when input voltage exceeds 15 V and robust brownout immunity is needed above 10 V. |
| TL494CN | Fixed-frequency voltage-mode controller; dual-output, adjustable dead time, no integrated current sense comparator. | Requires external current sensing and amplification; supports push-pull and half-bridge topologies. | Choose for multi-rail supplies or when independent control of two switches is required. |
Compared with UC3842BN, E-UC3843BN offers lower UVLO for 12 V input systems but lacks high-voltage tolerance; versus TL494CN, it integrates current sensing and simplifies flyback design but sacrifices dual-output flexibility and voltage-mode stability margins.
Availability
E-UC3843BN is available at Aetrix Electronics and suitable for AC-DC adapters, battery chargers, and industrial DC-DC converters requiring stable component supply, long-term lifecycle support, and consistent parametric performance across manufacturing lots.
Supply support for E-UC3843BN 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 UC384xB series was developed for cost-effective, high-reliability current-mode SMPS control in consumer and industrial power supplies, emphasizing minimal external component count and robust operation under line and load transients.
FAQ
What is the maximum recommended operating frequency for E-UC3843BN?
The UC3843BN oscillator is guaranteed at 250 kHz and supports operation up to 500 kHz with appropriate RT/CT values and layout optimization. At 500 kHz, propagation delays and gate drive losses increase significantly; practical designs typically limit to 300–400 kHz to maintain efficiency and stability, especially with high-side MOSFETs and unshielded transformers.
Can E-UC3843BN drive a P-channel MOSFET directly?
No - the OUTPUT pin is a totem-pole stage designed to source current when high and sink when low, making it ideal for N-channel MOSFETs with source grounded. Driving a P-channel high-side switch requires level-shifting circuitry or an external driver, as the IC lacks a floating high-side gate drive output or bootstrap capability.
How does the UVLO hysteresis affect system behavior during input dips?
With 8.5 V turn-on and 7.9 V turn-off, the 0.6 V hysteresis prevents oscillatory restart during marginal input conditions. If VCC drops below 7.9 V, the IC shuts down completely and holds OUTPUT low; it only resumes switching once VCC rises above 8.5 V, ensuring clean, chatter-free recovery without repeated pulse bursts.
Is external slope compensation required when using E-UC3843BN in DCM flyback?
No - slope compensation is only necessary in continuous conduction mode (CCM) flyback or boost converters to prevent subharmonic oscillation when duty cycle exceeds 50%. In DCM operation, the inductor current fully resets each cycle, eliminating the need for added ramp compensation on the ISENSE pin.
E-UC3843BN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Type:
- Transistor Driver
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Boost, Flyback
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 7.6V ~ 30V
- Frequency - Switching:
- Up to 500kHz
- Duty Cycle (Max):
- 96%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Frequency Control
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-Mini DIP
E-UC3843BN FAQ
1.How can I place an order for E-UC3843BN through Aetrix?
Please submit a Request for Quotation (RFQ) for E-UC3843BN 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 E-UC3843BN reliable?
The price and inventory of E-UC3843BN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for E-UC3843BN is usually 5 days.
3.What payment methods are accepted for E-UC3843BN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for E-UC3843BN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for E-UC3843BN?
E-UC3843BN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your E-UC3843BN 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 E-UC3843BN?
For technical support, including E-UC3843BN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your E-UC3843BN requirements.
6.How does Aetrix verify that E-UC3843BN is sourced from the original manufacturer or authorized distributors?
All E-UC3843BN 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 E-UC3843BN meets industry standards.
7.What is the process for return or replacement of E-UC3843BN?
All E-UC3843BN units undergo pre-shipment inspection (PSI). If there is an issue with E-UC3843BN, 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 E-UC3843BN part is unused and in its original packaging.
Return procedure for E-UC3843BN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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