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LM517701

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78V wide-VIN bidirectional 4-switch buck-boost controller

Product details

Rating Catalog Topology Buck-Boost Vin (max) (V) 78 Vin (min) (V) 2.8 Vout (max) (V) 60 Vout (min) (V) 3.3 Features Adjustable current limit, Dynamic voltage scaling, Enable, Frequency synchronization, Light-load efficiency, Load Disconnect, Power good, Spread Spectrum, Synchronous rectification, Tracking, UVLO adjustable Operating temperature range (°C) -40 to 125 Iq (typ) (µA) 60 Duty cycle (max) (%) 100 EMI features Frequency Dithering, Spread Spectrum
Rating Catalog Topology Buck-Boost Vin (max) (V) 78 Vin (min) (V) 2.8 Vout (max) (V) 60 Vout (min) (V) 3.3 Features Adjustable current limit, Dynamic voltage scaling, Enable, Frequency synchronization, Light-load efficiency, Load Disconnect, Power good, Spread Spectrum, Synchronous rectification, Tracking, UVLO adjustable Operating temperature range (°C) -40 to 125 Iq (typ) (µA) 60 Duty cycle (max) (%) 100 EMI features Frequency Dithering, Spread Spectrum
HTSSOP (DCP) 38 62.08 mm² 9.7 x 6.4
  • Wide input range from 3.5V to 78V (85V absolute maximum)
    • Minimum 2.8V when V(BIAS) > 3.5V
  • Output voltage from 3.3V to 78V
  • Low shutdown IQ of 3µA
  • Low operating IQ of 60µA
  • 3% reverse current limit accuracy for precise charging currents
  • Average input and output current monitor or limiter
  • Dynamic output voltage tracking for PWM or analog input signals
  • Power save mode (PSM) selectable for high light load efficiency
  • Two integrated high-voltage supply LDOs with automatic selection
  • Fixed frequency across all operating modes (boost, buck-boost, buck)
    • Forced PWM mode selectable
    • Switching up to 1.8MHz for small solution and component size
    • External clock synchronization
  • Spread spectrum operation selectable
  • Adjustable undervoltage protection
  • Hiccup overcurrent and short protection
  • Wide input range from 3.5V to 78V (85V absolute maximum)
    • Minimum 2.8V when V(BIAS) > 3.5V
  • Output voltage from 3.3V to 78V
  • Low shutdown IQ of 3µA
  • Low operating IQ of 60µA
  • 3% reverse current limit accuracy for precise charging currents
  • Average input and output current monitor or limiter
  • Dynamic output voltage tracking for PWM or analog input signals
  • Power save mode (PSM) selectable for high light load efficiency
  • Two integrated high-voltage supply LDOs with automatic selection
  • Fixed frequency across all operating modes (boost, buck-boost, buck)
    • Forced PWM mode selectable
    • Switching up to 1.8MHz for small solution and component size
    • External clock synchronization
  • Spread spectrum operation selectable
  • Adjustable undervoltage protection
  • Hiccup overcurrent and short protection

The LM51770x is a four switch buck-boost controller. The device provides a regulated output voltage if the input voltage is higher, equal, or lower than the adjusted output voltage. In power save mode, the device supports high efficiency with low output loads due to its low quiescence currents. In power save mode, the device supports high efficiency close to 99% efficiency over the full range of the output current. The LM51770x runs at a fixed switching frequency, which is set through the RT or SYNC pin. The switching frequency remains the same during buck, boost, and buck-boost operation. The integrated and optional average current monitor helps monitor and limit input and output current of the LM51770x. This feature also supports charging backup power elements, like batteries or capacitors, with constant current (CC) and constant voltage (CV).

The LM51770x is a four switch buck-boost controller. The device provides a regulated output voltage if the input voltage is higher, equal, or lower than the adjusted output voltage. In power save mode, the device supports high efficiency with low output loads due to its low quiescence currents. In power save mode, the device supports high efficiency close to 99% efficiency over the full range of the output current. The LM51770x runs at a fixed switching frequency, which is set through the RT or SYNC pin. The switching frequency remains the same during buck, boost, and buck-boost operation. The integrated and optional average current monitor helps monitor and limit input and output current of the LM51770x. This feature also supports charging backup power elements, like batteries or capacitors, with constant current (CC) and constant voltage (CV).

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Technical documentation

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* Data sheet LM51770x 78V Wide VIN Bidirectional 4-Switch Buck-Boost Controller datasheet (Rev. A) PDF | HTML 20 Aug 2025

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Evaluation board

LM5177EVM-HP — LM5177 evaluation module with four switch buck-boost controller

The LM5177EVM-HP demonstrates a flexible high power buck-boost design using the LM5177 wide-vin buck-boost controller. The evaluation module is configured to operate from input voltage range of 4.2 V to 36 V and provide a regulated 16-V output with up to 9.4 A of load current.
User guide: PDF | HTML
Not available on TI.com
Calculation tool

LM51770-QUICKSTART-CALC LM51770 BuckBoost Quickstart Calculator Tool

LM51770 BuckBoost Quickstart Calculator Tool. This standalone tool facilitates and assists the power supply engineer with the design of a DC/DC buck-boost converter based on the LM51770.
Supported products & hardware

Supported products & hardware

Products
AC/DC & DC/DC controllers (external FET)
LM51770 78V wide-VIN bidirectional 4-switch buck-boost controller LM51770-Q1 78V wide VIN bidirectional 4-switch buck-boost controller LM517701 78V wide-VIN bidirectional 4-switch buck-boost controller
Hardware development
Evaluation board
LM51770EVM-HV LM51770 buck-boost controller evaluation module
Package Pins CAD symbols, footprints & 3D models
HTSSOP (DCP) 38 Ultra Librarian

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