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Current-Mode PWM Controllers for Isolated Power Supplies

SOT23 Universal Off-Line Power Supply Controller

Product Details

Key Features

Parametric specs for Isolated Power Supplies
VIN (V) (min) 24
VIN (V) (max) 1000
Topology Flyback
Application (VIN) Networking (48V)
Power Over Ethernet (32-58V)
Telecom (36-72V)
Universal Off-line (90-240VAC)
Control Loop Current Mode
Feedback Opto
Switching Frequency (kHz) 262
Duty Cycle (%) (max) 75
Oper. Temp. (°C) -40 to +85
Package/Pins SOT23/6
UMAX/8
Budgetary
Price (See Notes)
0.77
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Simplified Block Diagram

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Parameters

Parametric specs for Isolated Power Supplies
VIN (V) (min) 24
VIN (V) (max) 1000
Topology Flyback
Application (VIN) Networking (48V)
Power Over Ethernet (32-58V)
Telecom (36-72V)
Universal Off-line (90-240VAC)
Control Loop Current Mode
Feedback Opto
Switching Frequency (kHz) 262
Duty Cycle (%) (max) 75
Oper. Temp. (°C) -40 to +85
Package/Pins SOT23/6
UMAX/8
Budgetary
Price (See Notes)
0.77

Key Features

  • Available in a Tiny 6-Pin SOT23 Package
  • 50µA Typical Startup Current
  • 1.2mA Typical Operating Current
  • Large UVLO Hysteresis of 14V
  • Fixed Switching Frequency of 262kHz ±12%
  • 50% Maximum Duty Cycle Limit (MAX5021)
  • 75% Maximum Duty Cycle Limit (MAX5022)
  • 60ns Cycle-by-Cycle Current-Limit Response Time

Applications/Uses

  • Isolated Power Supplies
  • Low-Power Telecom Power Supplies
  • Mobile Phone Chargers
  • Standby Power Supplies
  • Universal Offline Power Supplies

Description

The MAX5021/MAX5022 current-mode PWM controllers contain all the control circuitry required for the design of wide input voltage range isolated power supplies. These devices are well suited for use in universal input (85VAC to 265VAC) off-line or telecom (-36VDC to -72VDC) power supplies.

An undervoltage lockout (UVLO) circuit with large hysteresis coupled with low startup and operating current reduce power dissipation in the startup resistor and allow use of ceramic bypass capacitors. The 262kHz switching frequency is internally trimmed to }12% accuracy; this allows the optimization of the magnetic and filter components resulting in compact, cost-effective power supplies. The MAX5021 with 50% maximum duty cycle and MAX5022 with 75% maximum duty cycle are recommended for forward converters and flyback converters, respectively. The MAX5021/MAX5022 are available in 6-pin SOT23, 8-pin µMAX, and 8-pin DIP packages and are rated for operation over the -40‹C to +85‹C temperature range.

Simplified Block Diagram

MAX5021, MAX5022: Typical Operating Circuit MAX5021, MAX5022: Typical Operating Circuit 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 .