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AC-DC and DC-DC Peak-Current-Mode Converters for Flyback/Boost Applications

Peak-Current-Mode Converters Enable Compact, Cost-Effective, and Highly Flexible Isolated/Nonisolated Power Supplies

Product Details

Key Features

Parametric specs for Isolated Power Supplies
VIN (V) (min) 4.5
VIN (V) (max) 36
Topology Flyback
Application (VIN) Base Station (24V)
Industrial (24V)
Switch Type Internal
Control Loop Current Mode
Feedback Linear
Opto
Switching Frequency (kHz) 500
Duty Cycle (%) (max) 92
Oper. Temp. (°C) -40 to +125
Package/Pins TQFN/16
Budgetary
Price (See Notes)
1.34
Parametric specs for Step-Up Switching Regulators
VIN (V) (min) 4.5
VIN (V) (max) 36
VOUT1 (V) (min) 1.25
VOUT1 (V) (max) 65
IOUT1 (A) (max) 2
Switch Type Internal
Output Adjust. Method Resistor
Power Good Signal Yes
Synchronous Switching? Yes
ICC (mA) (typ) 2
# DC-DC Outputs 1
Switching Frequency (kHz) 500
Package/Pins TQFN/16
Budgetary
Price (See Notes)
1.34
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Simplified Block Diagram

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Parameters

Parametric specs for Isolated Power Supplies
VIN (V) (min) 4.5
VIN (V) (max) 36
Topology Flyback
Application (VIN) Base Station (24V)
Industrial (24V)
Switch Type Internal
Control Loop Current Mode
Feedback Linear
Opto
Switching Frequency (kHz) 500
Duty Cycle (%) (max) 92
Oper. Temp. (°C) -40 to +125
Package/Pins TQFN/16
Budgetary
Price (See Notes)
1.34
Parametric specs for Step-Up Switching Regulators
VIN (V) (min) 4.5
VIN (V) (max) 36
VOUT1 (V) (min) 1.25
VOUT1 (V) (max) 65
IOUT1 (A) (max) 2
Switch Type Internal
Output Adjust. Method Resistor
Power Good Signal Yes
Synchronous Switching? Yes
ICC (mA) (typ) 2
# DC-DC Outputs 1
Switching Frequency (kHz) 500
Package/Pins TQFN/16
Budgetary
Price (See Notes)
1.34

Key Features

  • Peak Current-Mode Converter
  • Current-Mode Control Provides Excellent Transient Response
  • Fixed Switching Frequency
    • 250kHz: MAX17498A/MAX17498C
    • 500kHz: MAX17498B
  • Flexible Error Amplifier to Regulate Both Positive and Negative Outputs
  • Programmable Soft-Start to Reduce Input Inrush Current
  • Programmable Voltage or Current Soft-Start
  • Power-Good Signal (PGOOD)
  • Reduced Power Dissipation Under Fault
    • Overcurrent Protection
    • Thermal Shutdown with Hysteresis
  • Robust Protection Features
    • Programmable Current Limit
    • Input Overvoltage Protection
  • Optimized Loop Performance
    • Fixed Default Slope Compensation in Current Soft-Start
    • Fixed Default and Programmable Slope Compensation in Voltage Soft-Start
  • High Efficiency
    • Low RDSON, 175mΩ, 65V Rated Internal n-Channel MOSFET
    • No Current-Sense Resistor
  • Optional Spread Spectrum
  • Space-Saving, 16-Pin (3mm x 3mm) TQFN Package

Applications/Uses

  • Front-End AC/DC Power Supplies for Industrial Applications (Isolated and Nonisolated)
  • Telecom Power Supplies
  • Wide Input Range DC Input Flyback/Boost Industrial Power Supplies

Description

The MAX17498A/MAX17498B/MAX17498C devices are current-mode fixed-frequency flyback/boost converters with a minimum number of external components. They contain all the control circuitry required to design wide input voltage isolated and nonisolated power supplies. The MAX17498A has its rising/falling undervoltage lockout (UVLO) thresholds optimized for universal offline (85V AC to 265V AC) applications, while the MAX17498B/MAX17498C support UVLO thresholds suitable to low-voltage DC-DC applications.

The switching frequency of the MAX17498A/MAX17498C is 250kHz, while that of the MAX17498B is 500kHz. These frequencies allow the use of tiny magnetic and filter components, resulting in compact, cost-effective power supplies. An EN/UVLO input allows the user to start the power supply precisely at the desired input voltage, while also functioning as an on/off pin. The OVI pin enables implementation of an input overvoltage-protection scheme that ensures that the converter shuts down when the DC input voltage exceeds the desired maximum value.

The devices incorporate a flexible error amplifier and an accurate reference voltage (REF) to enable the end user to regulate both positive and negative outputs. Programmable current limit allows proper sizing and protection of the primary switching FET. The devices support a maximum duty cycle greater than 92% and provide programmable slope compensation to allow optimization of control loop performance. The devices provide an open-drain PGOOD pin that serves as a power-good indicator and enters the high-impedance state to indicate that the flyback/boost converter is in regulation. An SS pin allows programmable soft-start time for the flyback/boost converter. Hiccup-mode overcurrent protection and thermal shutdown are provided to minimize dissipation under overcurrent and overtemperature fault conditions. The devices are available in a space-saving, 16-pin (3mm x 3mm) TQFN package with 0.5mm lead spacing.

Simplified Block Diagram

MAX17498A/MAX17498B/MAX17498C: Boost Power Supply MAX17498A/MAX17498B/MAX17498C: Boost Power Supply Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .