E-UC3844BD1 - 500kHz Current Mode PWM Controller, 8-SOIC
부품 번호: E-UC3844BD1 ✓ 활성| 수량 | 단가 | 합계 |
|---|---|---|
| 1 | $1.42 | $1.42 |
| 10 | $1.21 | $12.10 |
| 100 | $1.02 | $102.00 |
| 500 | $0.86 | $430.00 |
| 1,000 | $0.71 | $710.00 |
E-UC3844BD1 개요
A current-mode PWM controller is an integrated circuit that regulates output voltage by directly modulating the peak inductor current on a cycle-by-cycle basis, instead of controlling only the output voltage. This controller category sits within the broader hierarchy of PWM controllers -> switching controllers -> DC-DC controllers -> power management ICs -> semiconductors. Current-mode control provides inherent input-voltage feed-forward, automatic duty-cycle correction on input transients, and simplified closed-loop compensation because the inductor pole moves with the conversion ratio, leaving a single-pole output filter.
Key features include an on-chip 5 V reference with under-voltage-lockout (UVLO) thresholds optimized for 16 V turn-on / 10 V turn-off, low start-up current of 0.5 mA typical, totem-pole output capable of 1 A peak gate drive, automatic feed-forward compensation, and a latching PWM architecture with cycle-by-cycle current limiting. The internal totem-pole driver can directly switch the gate of a power MOSFET or an IGBT, and the synchronous step-down topology variant supports input voltages up to 25 V.
The E-UC3844BD1 uses a bipolar control loop with a trimmed precision current-sense amplifier feeding the PWM comparator. Compared to the UC3842 (no UVLO) and UC3843 (8.4 V/7.6 V UVLO) variants, the E-UC3844BD1 offers the 16 V/10 V UVLO window favored for universal-input offline flyback converters. The architecture is built on the same die as the rest of the UC384xB family, with pin-for-pin equivalence to the UC3842BD1, UC3843BD1, UC3844BD1, UC3845BD1 series; only the UVLO thresholds and maximum duty cycle differ.
Typical applications include isolated AC-DC adapters, auxiliary supplies in industrial and white-goods equipment, isolated flyback telecom converters, and battery-charging front-ends. Designers select this part when they need an industrial-standard, low-cost current-mode controller with 50% duty cycle for forward or active-clamp topologies and a 16 V UVLO window for offline rectification.
When designing with this device, place the current-sense resistor between the source of the external power switch and ground to enable cycle-by-cycle limiting. The 1 A totem-pole output stage requires a gate resistor of 10 ohm to 47 ohm to damp ringing when driving a large MOSFET gate, and the VREF bypass capacitor (typically 0.1 uF ceramic in parallel with 1 uF tantalum) must be placed within 5 mm of the VREF pin to keep loop stability.
This page consolidates STMicroelectronics literature, authorized distributor stock, same-family alternatives such as UC3842BD1/UC3843BD1, and direct cross-brand pin-compatible drop-in replacements (UC3844BD1 from onsemi and TI) into one comparison matrix that is not available on any single distributor product page.
드롭인 대체품: E-UC3844BD1 — 동일 패키지, 핀 호환. PCB 재작업이 필요한 다른 패키지 부품은 제외됩니다.
이 시리즈의 변형
다음과 드롭인 호환되는 동일 시리즈 모델: E-UC3844BD1 (동일 폼 팩터 및 풋프린트) — 차이점: Maximum Duty Cycle.
빠른 비교 도구 — 나란히 비교할 대체 부품을 선택하십시오:
UC3844BD1
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
UC3842BD1
✅ 드롭인✓ 재고 있음
$0.1485 / 개
데이터시트 보기 →UC3845BD1
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
UC3844BD1
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
UC3844
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
UC2844BN
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
E-UC3844BD1 최대 정격 & 전기적 특성
| PWM Type | Current Mode |
| 출력 수 | 1 |
| 토폴로지 | Boost, Flyback (Isolation Capable, Step-Up/Step-Down) |
| 패키지 / 케이스 | 8-SOIC (3.90 mm body width) |
| Supply Voltage Range | 11.5 V to 25 V |
| Maximum Switching Frequency | 500 kHz |
| Oscillator Frequency (Guaranteed) | 250 kHz |
| Maximum Duty Cycle | 50% |
| 기동 전류 | 0.5 mA typical |
| Output Current (Peak, Gate Drive) | 1 A |
| 기준 전압 | 5 V (internal bandgap) |
| 실장 유형 | Surface Mount |
| RoHS 상태 | Compliant |
| Lead-Free | Yes |
| MSL 레벨 | 1 |
E-UC3844BD1 핀 구성
| 핀 1 | COMP — Error amplifier compensation network |
| 핀 2 | VFB — Feedback voltage input (error amplifier inverting input) |
| 핀 3 | ISENSE — Current-sense input for cycle-by-cycle current limit and PWM ramp |
| 핀 4 | RT/CT — Oscillator timing resistor and capacitor connection |
| 핀 5 | GND — Ground (0 V reference) |
| 핀 6 | OUTPUT — Gate-drive totem-pole output (1 A peak) |
| 핀 7 | VCC — Supply voltage (11.5 V to 25 V) |
| 핀 8 | VREF — 5 V internal reference output |
일반적인 애플리케이션
E-UC3844BD1 적합 용도: 6 애플리케이션s: Universal-Input Offline Flyback Converter, Active-Clamp Forward Converter, DC-DC Step-Down Auxiliary Supply, Battery Charger Front-End (CC/CV), LED Driver Power Stage, White Goods and Appliance SMPS.
Universal-Input Offline Flyback Converter
The E-UC3844BD1's 16 V / 10 V UVLO thresholds and 50% maximum duty cycle make it a textbook controller for universal-input (85 V AC to 265 V AC) isolated flyback converters in the 5 W to 60 W range. The current-mode control inherent to the device simplifies the small-signal loop - designers typically realize a single-pole Type-II compensation network using only the COMP pin to ground with a 10 kohm resistor and 0.01 uF capacitor. With 1 A peak gate-drive current, the controller directly switches an 800 V MOSFET without an external driver stage. According to the UC384xB datasheet, the trimmed 250 kHz oscillator guarantee is essential for EMI margin in universal-input designs where the rectified rail varies 3:1 and predictable switching frequency is mandatory for input-filter sizing.
추천
Active-Clamp Forward Converter
For telecom and industrial isolated bus converters using the active-clamp forward topology, the E-UC3844BD1's hard 50% duty-cycle clamp prevents transformer saturation during load transients and guarantees reset of the clamp capacitor every switching period. The 500 kHz maximum oscillator allows 250 kHz to 400 kHz operation, balancing magnetic size against switching loss. Designers normally pair the controller with a UCC27322 4 A gate driver (in the XAIPART Site MPN list) downstream of the E-UC3844BD1's 1 A pin-6 output to drive the primary-side main MOSFET at sub-30 ns rise times. The cycle-by-cycle current limiting through the ISENSE pin (3) protects the active-clamp MOSFET and primary switch against short-circuit faults inherent to the topology.
추천
DC-DC Step-Down Auxiliary Supply
In industrial PLCs and motor-drive systems, the E-UC3844BD1 forms the heart of an isolated 24 V to 5 V auxiliary supply that rails the control logic between main converter start-up and steady-state operation. Configured in a single-ended forward topology with a transformer turns ratio chosen for 5 V output at 50% duty, the controller delivers up to 1 A gate-drive current that directly charges a logic-level MOSFET gate. The 11.5 V minimum supply rail enables direct bias from a 12 V or 15 V industrial backplane, eliminating auxiliary windings during board bring-up. The controller's automatic feed-forward compensation - a feature called out in the STMicroelectronics datasheet - automatically adjusts duty cycle for input-voltage variations on the 24 V rail without designer intervention, simplifying compliance with industrial transient standards.
추천
Battery Charger Front-End (CC/CV)
When the E-UC3844BD1 is wired with external TL431-type feedback into the VFB (pin 2) and current-sense resistor into ISENSE (pin 3), it forms the primary-side regulation core of an isolated constant-current / constant-voltage battery charger for 12 V lead-acid or 24 V Li-ion packs. The 0.5 mA typical start-up current minimizes auxiliary-winding burden during pre-charge, and the latching PWM behavior is ideal for charger topologies that must latch off on fault detection - a current-sense threshold of 1 V on ISENSE provides hardware-level over-current protection. The 500 kHz maximum oscillator enables transformer and output-filter magnetics small enough for handheld and portable charger form factors below 100 W.
추천
LED Driver Power Stage
The E-UC3844BD1 supports isolated constant-current LED drivers in commercial lighting and street-lamp fixtures rated 30 W to 150 W. With VFB configured as a current-sense amplifier input from the secondary side (via TL431 + optocoupler), the controller regulates LED string current rather than voltage, eliminating the need for an analog dimming interface. The 16 V UVLO window prevents flicker on power-line brown-out, a common complaint in outdoor lighting. The 50% duty-cycle clamp suits single-ended forward stages that drive high-brightness LEDs at 350 mA to 1.05 A. The internal 5 V reference can directly bias the optocoupler LED without an extra LDO, reducing BOM cost in cost-sensitive lighting designs.
추천
White Goods and Appliance SMPS
Washing machines, refrigerators, induction cooktops, and HVAC blower controllers all rely on the E-UC3844BD1 for low-cost auxiliary SMPS rails at 12 V / 5 V that power microcontrollers, display drivers, and sensor interfaces. The wide 11.5 V to 25 V supply range allows the controller to start from rectified mains directly through a startup resistor before the auxiliary winding takes over. The 0.5 mA start-up current, explicitly called out in the STMicroelectronics datasheet, draws minimal idle power between user interactions - meeting Energy Star and EU EcoDesign standby regulations. The 8-SOIC surface-mount footprint is compatible with automated SMT lines, keeping manufacturing cost low in high-volume appliance production.
추천
추천 제품 요약
엔지니어링 참조 데이터: E-UC3844BD1 — 비교, 설계 지침 및 규정 준수 정보.
선택 가이드
대체품과의 비교
| 파라미터 | 이 제품 | UC3844BD1 (ST) | UC3842BD1 | UC3845BD1 | UC3844BD1 (onsemi) | UC3844 (TI) | UC2844BN |
|---|---|---|---|---|---|---|---|
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | onsemi | Texas Instruments | Motorola Semiconductor |
| Package | 8-SOIC | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same | 8-DIP - through-hole, same pinout logic |
| Max Switching Frequency | 500 kHz | 500 kHz | 500 kHz | 500 kHz | 500 kHz | 500 kHz | 500 kHz |
| Max Duty Cycle | 50% | 50% | 100% | 100% | 50% | 50% | 50% |
| UVLO Thresholds | 16 V / 10 V (E-prefix variant) | 16 V / 10 V | No UVLO | 16 V / 10 V | 16 V / 10 V | 16 V / 10 V | 16 V / 10 V (industrial) |
| Supply Voltage Range | 11.5 V to 25 V | 11.5 V to 25 V | 11.5 V to 25 V | 11.5 V to 25 V | 11.5 V to 25 V | 11.5 V to 25 V | 11.5 V to 25 V |
| Start-up Current (typ) | 0.5 mA | 0.5 mA | 0.5 mA | 0.5 mA | 0.5 mA | 0.5 mA | 0.5 mA |
| Peak Gate Drive Current | 1 A | 1 A | 1 A | 1 A | 1 A | 1 A | 1 A |
주요 차별점
- E-prefix latest characterization and PCN compliance (vs UC3844BD1 (ST, no E-prefix))
- 16 V / 10 V UVLO tailors the part to offline rectification (vs UC3842BD1 (no UVLO) and UC3843BD1 (8.4 V / 7.6 V UVLO))
- Cross-brand pin-compatibility with onsemi and TI (vs onsemi UC3844BD1 and TI UC3844)
설계 노트
Place the VREF (pin 8) bypass capacitor within 5 mm of the package, using a 0.1 uF X7R ceramic in parallel with a 1 uF X5R ceramic. The VCC (pin 7) decoupling requires a 1 uF ceramic plus a 47 uF bulk aluminum-polymer for hold-up during start-up. Gate-drive output (pin 6) trace must be at least 20 mil wide and shorter than 25 mm to limit peak-current-induced ringing; add a 10 ohm to 47 ohm gate resistor in series to damp oscillation when driving a MOSFET with gate charge above 30 nC.
At 250 kHz switching with an 800 V MOSFET (Qg = 30 nC), the gate-drive loss in the E-UC3844BD1 is approximately 250 kHz x 30 nC x VCC = 188 mW, plus 5 mW quiescent - well within the 8-SOIC's 250 mW theta_JA=110 C/W thermal budget. Estimated: at 70 C ambient the junction rises 21.5 C above ambient, leaving 53.5 C margin to the 125 C maximum. For converters switching above 400 kHz or with Qg > 50 nC, consider a UCC27322 (XAIPART Site MPN list) external driver to keep this controller below 50% of its dissipation limit.
Never operate the E-UC3844BD1 with VCC below 11.5 V - the under-voltage lockout will rapidly cycle and stress the bootstrap capacitor. Do not let ISENSE (pin 3) exceed 1 V peak or the 1 A gate-drive output will latch off. Use a 100 ohm source-termination resistor between the current-sense resistor and pin 3 to suppress sub-100 ns ringing. Finally, the COMP pin (1) is internally pulled to 5 V at start-up; do not externally drive it above 6 V or the error amplifier will saturate and prevent normal regulation.
규정 준수 정보
RoHS and lead-free confirmed per STMicroelectronics product page. AEC-Q100 not applicable - this is an industrial/commercial PWM controller, not an automotive-qualified part. Halogen-free status not explicitly stated in the provided distributor data.
