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Switching Regulator - Switching Regulators 
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MAX5974F
Current-Mode PWM Controllers for Low-Cost Flyback Supplies
IEEE 802.3af/at-Compliant, Powered Device PWM Controllers for High-Efficiency Nonisolated DC-DC Converters
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Key Features
Applications/Uses
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Simplified Block Diagram
Technical Docs
| Data Sheet | Current-Mode PWM Controllers for Low-Cost Flyback Supplies | Nov 26, 2013 |
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Filtered SearchOur dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .
Parameters
Key Features
- Peak Current-Mode Control, Synchronous Flyback PWM Controller
- Synchronous MOSFET Driver Output
- Internal 1% Error Amplifier Eliminates Shunt Regulator and Optocoupler
- 100kHz to 600kHz Programmable ±8% Switching Frequency, Synchronization Up to 1.2MHz
- Programmable Frequency Dithering for Low-EMI, Spread-Spectrum Operation
- Programmable Dead Time, PWM Soft-Start, Current Slope Compensation
- Programmable Feed-Forward Maximum Duty-Cycle Clamp, 80% Maximum Limit
- Frequency Foldback for High-Efficiency Light-Load Operation
- Internal Bootstrap UVLO with Large Hysteresis
- 100µA (typ) Startup Supply Current
- Fast Cycle-by-Cycle Peak Current-Limit, 35ns Typical Propagation Delay
- 115ns Current-Sense Internal Leading-Edge Blanking
- Output Short-Circuit Protection with Hiccup Mode
- Internal 18V Zero Clamp on Supply Input
- 3mm x 3mm, Lead-Free, 16-Pin TQFN-EP
Applications/Uses
- High-Power PD (Beyond the 802.3af/at Standard)
- IP Phones
- PoE IEEE® 802.3af/at Powered Devices
- Security Cameras
- Wireless Access Nodes
Description
The MAX5974E/MAX5974F provide control for wide-input-voltage, current-mode PWM, nonisolated, synchronous flyback converters in Power-over-Ethernet (PoE) powered device (PD) applications. The MAX5974E is well-suited for universal or telecom input range, while the MAX5974F also accommodates low input voltage down to 8.4V.
The devices include several features to enhance supply efficiency, including a synchronous MOSFET driver output. The AUX driver drives an output synchronous rectifier to lower conduction losses. Programmable dead time between the AUX and main driver allows for zero-voltage switching (ZVS). Under light load conditions, the devices reduce the switching frequency (frequency foldback) to reduce switching losses.
An internal error amplifier with a 1% reference eliminates the need for an external shunt regulator and optocoupler.
The programmable frequency dithering feature provides low-EMI, spread-spectrum operation.
The MAX5974E/MAX5974F are available in 16-pin TQFN-EP packages and are rated for operation over the -40°C to +85°C temperature range.
The devices include several features to enhance supply efficiency, including a synchronous MOSFET driver output. The AUX driver drives an output synchronous rectifier to lower conduction losses. Programmable dead time between the AUX and main driver allows for zero-voltage switching (ZVS). Under light load conditions, the devices reduce the switching frequency (frequency foldback) to reduce switching losses.
An internal error amplifier with a 1% reference eliminates the need for an external shunt regulator and optocoupler.
The programmable frequency dithering feature provides low-EMI, spread-spectrum operation.
The MAX5974E/MAX5974F are available in 16-pin TQFN-EP packages and are rated for operation over the -40°C to +85°C temperature range.
Simplified Block Diagram
Technical Docs
| Data Sheet | Current-Mode PWM Controllers for Low-Cost Flyback Supplies | Nov 26, 2013 |
Support & Training
Search our knowledge base for answers to your technical questions.
Filtered SearchOur dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .
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