UC3824 - 1.5A High Speed PWM Controller | Texas Instruments
MPN: UC3824 ✓ Hoạt độngUC3824 Tóm tắt
A PWM controller is an integrated circuit that generates the pulse-width-modulated signals used to control the switching elements in a DC-DC converter or power supply. It forms the core of the control loop, regulating output voltage or current by varying the duty cycle of the switching waveform. The UC3824 belongs to the family of current-mode PWM controllers, which offer superior line regulation and simpler compensation compared to voltage-mode controllers. In the hierarchy of power management, it sits between the power stage (MOSFETs, transformers) and the supervisory circuitry, providing the precise timing and drive signals essential for efficient power conversion.
Key features of the UC3824 include a 50-ns propagation delay to output, enabling high-frequency operation with minimal phase lag. The dual totem-pole outputs can source and sink 1.5 A, providing robust gate drive for large MOSFETs. The device also includes a current-limit comparator with a 1-V threshold, a TTL-compatible shutdown port, and a soft-start pin that doubles as a maximum duty cycle clamp. The logic is fully latched to ensure jitter-free operation and prevent multiple pulses at the output.
Technically, the UC3824 uses a fixed-frequency, current-mode architecture with an internal oscillator whose frequency is set by external timing components RT and CT. The ramp generator is designed so that the voltage at Pin 9 crosses the 1-V threshold at the same time the desired maximum volt-second product is reached, allowing precise control of the duty cycle. The device's high-speed comparator and latch ensure accurate cycle-by-cycle current limiting, making it suitable for demanding applications such as push-pull and half-bridge converters.
Typical applications include switch-mode power supplies for telecommunications, industrial power converters, and battery chargers. The UC3824's high-frequency capability allows for smaller magnetic components, reducing overall system size and cost. Its double-ended output configuration makes it ideal for push-pull and full-bridge topologies where two interleaved drive signals are required.
When designing with the UC3824, careful attention must be paid to grounding and bypassing, as the high-speed switching can introduce noise. A ground plane is highly recommended, and the timing components should be placed close to the IC to minimize parasitic inductance. The soft-start pin should be used to limit inrush current during startup, and the current-limit threshold should be set appropriately for the application.
Bộ thay thế dễ dàng lắp đặt cho UC3824 — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
UC3824N
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
UC3825
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
UC3823
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
TL494CDT
⚡ Đồng góiLiên hệ để biết giá
Xem tài liệu →SG3524
⚡ Đồng gói ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
UC3824 Tỷ lệ tối đa & tính chất điện
| Input Voltage (VCC) | 30 V (max) |
| Output Current (Source/Sink) | 1.5 A |
| UVLO Threshold (On/Off) | 9.2 V / 8.4 V |
| Maximum Duty Cycle | 85% |
| Switching Frequency (Max) | 1 MHz |
| Propagation Delay to Output | 50 ns |
| Current Limit Threshold | 1 V |
| Khoảng nhiệt độ hoạt động | 0°C to 70°C |
| Package Type | 16-PDIP |
| Kiểu lắp đặt | Through Hole |
| Topology Support | Push-Pull, Half-Bridge, Full-Bridge |
| Control Method | Current Mode |
| Shutdown Port | TTL Compatible |
| Bắt đầu mềm | Yes (also max duty clamp) |
| Trạng thái RoHS | Compliant |
Cấu hình chân UC3824
| Chân 1 | INV — Inverting input of error amplifier |
| Chân 2 | NI — Non-inverting input of error amplifier |
| Chân 3 | EAOUT — Error amplifier output |
| Chân 4 | CLK — Clock input for synchronization |
| Chân 5 | RT — Timing resistor for oscillator |
| Chân 6 | CT — Timing capacitor for oscillator |
| Chân 7 | RAMP — Ramp input for current sensing |
| Chân 8 | SS — Soft-start and max duty clamp |
| Chân 9 | ILIM — Current limit sense input |
| Chân 10 | GND — Ground |
| Chân 11 | OUTA — Output A (totem-pole) |
| Chân 12 | VCC — Supply voltage |
| Chân 13 | OUTB — Output B (totem-pole) |
| Chân 14 | VREF — 5V reference output |
| Chân 15 | SD — Shutdown input (TTL compatible) |
| Chân 16 | GND — Ground (second pin) |
Ứng dụng tiêu biểu
UC3824 phù hợp cho 6 Áp dụngs: Push-Pull Converters, Half-Bridge Converters, Full-Bridge Converters, Battery Chargers, Telecom Power Supplies, Industrial Power Converters.
Push-Pull Converters
The UC3824's dual 1.5-A totem-pole outputs provide complementary drive signals for push-pull converters. Its high-speed operation (up to 1 MHz) allows for smaller transformers and improved power density. The 50-ns propagation delay ensures precise timing between the two output phases, reducing the risk of transformer saturation. With a maximum duty cycle of 85%, it can handle wide input voltage variations while maintaining regulation. The current-mode control provides inherent overcurrent protection, making it ideal for telecom and industrial power supplies.
Được đề xuất
Half-Bridge Converters
In half-bridge topologies, the UC3824 generates the two interleaved gate drive signals needed for the high-side and low-side MOSFETs. Its 1.5-A peak output current can drive large gate capacitances directly, eliminating the need for external buffer stages. The high switching frequency (up to 1 MHz) enables the use of smaller magnetic components, reducing the overall footprint of the power supply. The soft-start feature limits inrush current during startup, protecting the power stage. The TTL-compatible shutdown port allows for easy implementation of protection schemes.
Được đề xuất
Full-Bridge Converters
The UC3824 can be used in full-bridge converters by combining its two outputs with external logic to generate four drive signals. Its high-speed operation and 50-ns propagation delay ensure accurate phase-shift control, which is critical for zero-voltage switching (ZVS) techniques. The 1.5-A output current provides sufficient gate drive for high-power MOSFETs, while the current-limit comparator offers cycle-by-cycle protection. The device's wide input voltage range (up to 30 V) makes it suitable for industrial power supplies and battery chargers.
Được đề xuất
Battery Chargers
The UC3824 is well-suited for battery charger applications requiring high-frequency switching to reduce charger size. Its current-mode control provides accurate current limiting, essential for safe battery charging. The soft-start feature prevents inrush current when charging deeply discharged batteries. The 1.5-A gate drive can directly drive the switching MOSFETs in a buck or boost converter. The device's wide input voltage range accommodates various AC-DC adapter outputs, and the TTL shutdown port allows for easy implementation of charge termination logic.
Được đề xuất
Telecom Power Supplies
In telecom power supplies, the UC3824's high-frequency operation (up to 1 MHz) enables compact, high-density designs that meet the strict size constraints of telecom racks. Its 1.5-A output current can drive the large MOSFETs used in high-power converters, while the 50-ns propagation delay ensures fast transient response. The current-mode control provides excellent line and load regulation, critical for maintaining stable output voltages in telecom systems. The device's wide input voltage range (up to 30 V) allows it to operate from standard telecom bus voltages (e.g., 48 V with a pre-regulator).
Được đề xuất
Industrial Power Converters
The UC3824 is designed for industrial power converters that require high reliability and precise control. Its fully latched logic prevents multiple pulses, ensuring jitter-free operation in noisy industrial environments. The current-limit comparator with a 1-V threshold provides robust overcurrent protection, while the soft-start feature limits stress during startup. The device's wide operating temperature range (0°C to 70°C) covers most industrial applications. The high-speed operation allows for smaller magnetic components, reducing the overall cost and size of the converter.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho UC3824 — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | UC3824N | UC3825 | TL494 |
|---|---|---|---|---|
| Package | 16-PDIP | 16-PDIP | 16-PDIP | 16-PDIP |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Output Current (Source/Sink) | 1.5 A | 1.5 A | 1.5 A | 0.2 A |
| Maximum Switching Frequency | 1 MHz | 1 MHz | 1 MHz | 300 kHz |
| Propagation Delay to Output | 50 ns | 50 ns | 50 ns | 200 ns |
| UVLO Threshold (On/Off) | 9.2 V / 8.4 V | 9.2 V / 8.4 V | 8.4 V / 7.6 V | 7.0 V / 4.9 V |
| Maximum Duty Cycle | 85% | 85% | 85% | 45% |
| Current Limit Threshold | 1 V | 1 V | 1 V | 0.7 V |
Bảo phân biệt quan trọng
- High output current (1.5 A) compared to TL494's 200 mA (vsTL494)
- Fast propagation delay (50 ns) vs TL494's 200 ns (vsTL494)
- Higher UVLO thresholds (9.2V/8.4V) vs UC3825's 8.4V/7.6V (vsUC3825)
Ghi chú thiết kế
For high-speed operation up to 1 MHz, careful PCB layout is essential. Use a ground plane to minimize noise and ensure low-inductance paths for the gate drive signals. Place the timing components (RT, CT) close to the IC to reduce parasitic capacitance and inductance. Bypass the VCC pin with a 0.1-uF ceramic capacitor and a 10-uF electrolytic capacitor near the device.
The UC3824's 1.5-A output stage can dissipate significant power when driving large capacitive loads at high frequencies. Ensure adequate thermal management by providing copper pour on the PCB and considering the total power dissipation. The device's power dissipation can be estimated as P = VCC * ICC + (f * Qg * VCC) for each output, where Qg is the gate charge of the MOSFET.
Avoid exceeding the absolute maximum VCC of 30 V. The soft-start pin should not be left floating; connect a capacitor to ground to set the startup time. The current-limit sense resistor should be placed in the source path of the power MOSFET, and the ILIM pin should be filtered to avoid false triggering due to noise. Ensure the shutdown pin is properly terminated to prevent unintended shutdown.
Thông tin tuân thủ
RoHS compliant per TI product page. Not AEC-Q100 qualified. Lead-free per TI's environmental data.
