R1278 Series
30 V, 2 A Synchronous PWM Step-down DC/DC Converter

  • Description

    The R1278 is a 36 V maximum rated synchronous step-down DC/DC converter with built-in drivers.

    With the operating frequency at 2 MHz and a spread-spectrum clock generator, the interference effect on the AM band is small. When an input voltage drops, the switching frequency is automatically reduced to keep output voltage level constant.

    Key Benefits

    • Provides a high switching frequency at 2 MHz with the efficiency of 87%.
    • Maintains the output voltage constant when an input voltage drops by reducing a switching frequency to the minimum of 1/4.
    • Achieves the EMI noise reduction by using a spread spectrum clock generator. (Diffusion Rate: +10%).

  • Spec
    Consumer Industrial Automotive
    Input Voltage Range 3.6 V to 30.0 V (36.0 V)
    Operating Temperature Range -40°C to 105°C (125°C) -40°C to 125°C (150°C) -40°C to 125°C (150°C)
    Supply Current Typ. 1 mA
    Standby Current Typ. 4 µA
    Start-up Voltage 4.5 V
    Output Voltage Range Externally Adjustable: 3.3 V to 5.0 V
    Feedback Voltage 0.64 V
    Feedback Voltage Accuracy ±1.0%
    Output Current 2 A
    Driver ON-resistance High side: Typ. 0.145 Ω, Low side: Typ. 0.095 Ω
    Oscillator Frequency Typ. 2 MHz
    Package HSOP-18

    Protections / Functions

    TSD ILX OCP OVP UVLO OVLO Reverse Shutdown Soft Start SSCG PGOOD Auto Discharge Anti-ringing Sequencing Max Duty Ext. Phase LED Adjust
  • Technical
    • Typical Application

      Typical Application
    • Efficiency (VOUT=5V)

      Efficiency (VOUT=5V)

    • Related Links

      • Prime Designer

        Online Design Tool

        Registration to myNISD is required to use some of the functions, such as simulations.

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  • Quality &
    • Refer to the datasheets for the details on the product.
    • The package file or the datasheet includes package dimensions, taping specifications, taping reels dimensions, power dissipations, and recommended land pattern.

Download Datasheet

Functional Description

TSD Thermal Shutdown Function
ILX LX Current Limit Function
OCP Overcurrent Protection
OVP Overvoltage Protection
UVLO Undervoltage Lockout Protection
OVLO Overvoltage Lockout Protection
Reverse Reverse Current Protection Circuit
Shutdown Shutdown Function
Soft Start Soft Start Function
SSCG Spread Spectrum Clock Generator Function
PGOOD Power Good Output
Auto Discharge Auto Discharge Function
Anti-ringing Anti-ringing Switch Function
Sequencing Start-up Sequencing Control
Max Duty Maximum Duty Cycle
Ext. Phase Externally Adjustable Phase Compensation
LED Adjust LED High-speed Dimming Control

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