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LM5121
  • LM5121
  • LM5121

LM5121

ACTIVE

3-65V Wide Vin, Current Mode Synchronous Boost with Disconnection Switch Control

Texas Instruments LM5121 Product Info

1 April 2026 3

Parameters

Rating

Catalog

Topology

Boost, Flyback, Forward, SEPIC

Vin (max) (V)

65

Vin (min) (V)

3

Vout (max) (V)

100

Vout (min) (V)

3

Control mode

current mode

Features

Adjustable current limit, Enable, Frequency synchronization, Light-load efficiency, Synchronous rectification, UVLO adjustable

Duty cycle (max) (%)

100

Iq (typ) (A)

0.004

Operating temperature range (°C)

-40 to 125

Package

HTSSOP (PWP)-20-41.6 mm² 6.5 x 6.4

Features

  • AEC-Q100 Qualified with the following results:
    • Device Temperature Grade 1: –40°C to +125°C
      Ambient Operating Temperature Range
    • Device HBM ESD Classification Level 2
    • Device CDM ESD Classification Level C6
  • Maximum Input Voltage: 65 V
  • Min Input Voltage: 3.0 V (4.5 V for startup)
  • Output Voltage Up to 100 V
  • Bypass (VOUT = VIN) Operation
  • 1.2-V Reference with ±1.0% Accuracy
  • Free-Run/Synchronizable up to 1 MHz
  • Peak Current Mode Control
  • Robust Integrated 3-A Gate Drivers
  • Adaptive Dead-Time Control
  • Optional Diode Emulation Mode
  • Programmable Cycle-by-Cycle Current Limit
  • Programmable Line UVLO
  • Programmable Soft-Start
  • Thermal Shutdown Protection
  • Low Shutdown Quiescent Current: 9 µA
  • Programmable Slope Compensation
  • Programmable Skip Cycle Mode Reduces
    Standby Power
  • Supports External VCC Bias Supply Option
  • Load Disconnection in Shutdown Mode (True
    Shutdown)
  • Inrush Current Limiting
  • Hiccup Mode Short Circuit/Overload Protection
  • Circuit Breaker Function
  • Capable of Input Transient Suppression
  • Capable of Reverse Battery Protection
  • Thermally Enhanced 20-Pin HTSSOP
  • AEC-Q100 Qualified with the following results:
    • Device Temperature Grade 1: –40°C to +125°C
      Ambient Operating Temperature Range
    • Device HBM ESD Classification Level 2
    • Device CDM ESD Classification Level C6
  • Maximum Input Voltage: 65 V
  • Min Input Voltage: 3.0 V (4.5 V for startup)
  • Output Voltage Up to 100 V
  • Bypass (VOUT = VIN) Operation
  • 1.2-V Reference with ±1.0% Accuracy
  • Free-Run/Synchronizable up to 1 MHz
  • Peak Current Mode Control
  • Robust Integrated 3-A Gate Drivers
  • Adaptive Dead-Time Control
  • Optional Diode Emulation Mode
  • Programmable Cycle-by-Cycle Current Limit
  • Programmable Line UVLO
  • Programmable Soft-Start
  • Thermal Shutdown Protection
  • Low Shutdown Quiescent Current: 9 µA
  • Programmable Slope Compensation
  • Programmable Skip Cycle Mode Reduces
    Standby Power
  • Supports External VCC Bias Supply Option
  • Load Disconnection in Shutdown Mode (True
    Shutdown)
  • Inrush Current Limiting
  • Hiccup Mode Short Circuit/Overload Protection
  • Circuit Breaker Function
  • Capable of Input Transient Suppression
  • Capable of Reverse Battery Protection
  • Thermally Enhanced 20-Pin HTSSOP

Description

The LM5121 is a synchronous boost controller intended for high-efficiency, high-power boost regulator applications. The control method is based upon peak current mode control. Current mode control provides inherent line feed-forward, cycle-by-cycle current limiting and ease of loop compensation.

The switching frequency is programmable up to 1 MHz. Higher efficiency is achieved using two robust N-channel MOSFET gate drivers with adaptive dead-time control. A user-selectable diode emulation mode enables discontinuous mode operation for improved efficiency at light load conditions.

The LM5121 provides disconnection switch control which completely disconnects the output from the input during an output short or a shutdown condition. During start-up sequence, inrush current is limited by the disconnection switch control.

An internal charge pump allows 100% duty cycle operation of the high-side synchronous switch (Bypass operation). Additional features include thermal shutdown, frequency synchronization, hiccup mode current limit and adjustable line undervoltage lockout.

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