R1275 Series
2A 30V Input Forced PWM Step-down DC/DC Converter with Synchronous Rectifier

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  • Description

    The R1275 is a 36-V synchronous step-down DC/DC converter with built-in drivers. It is designed for industrial equipment, OA equipment and home electronics that require a 24-V input.

    It operates at a 2-MHz switching frequency, which allows to use a small inductor to ensure a high transient response and to maintain a high efficiency at heavy load condition. Using a spread spectrum clock generator, the EMI noise can be reduced.

    Under cranking condition, the switching frequency is automatically reduced to keep output voltage level constant.

    • Provides a high switching frequency at 2 MHz with an efficiency of 87%.
    • Maintains the output voltage constant by reducing a switching frequency to the minimum 1/4 when an input-output voltage difference is small.
    • Achieves the EMI noise reduction by using a spread spectrum clock generator. (Diffusion Rate: +8%).

  • 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 105°C (125°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

      *1) Connecting a Schottky barrier diode between LX and GND can reduce the LX noise and improve the efficiency.

    • Efficiency (VOUT = 5 V)

      Efficiency (VOUT = 5 V)

    • 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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