R1270 Series
3A 34V Input PWM/VFM Step-down DC/DC Converter with PLL Synchronization

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  • Description

    The R1270 Series are 34V input (Absolute maximum rating: 36V), CMOS-based PWM/VFM step-down DC/DC converters capable of outputting the maximum 3A* current. The R1270 is selectable from two control types - PWM control or PWM/VFM auto switching control in which mode automatically switches to high-efficiency VFM mode in low output current. The R1270 includes a soft start circuit, a fold-back protection circuit and a latch protection circuit (only A Version). By simply using an inductor, resistors, and capacitors as external components, a high-efficiency step-down DC/DC converter can be easily configured. The R1270 can be synchronized externally by PLL.

    *) This is an approximate value, because output current depending on conditions and external parts.

  • Spec
    Consumer Industrial Automotive
    Input Voltage Range 3.6 V to 34.0 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. 18 µA
    Standby Current Typ. 0 µA
    Output Voltage Range Externally Adjustable: 0.8 V to 31.6 V
    Feedback Voltage 0.8 V
    Feedback Voltage Accuracy ±8 mV
    Feedback Voltage Temperature Coefficient Typ. ±100 ppm/°C (−40°C ≤ Ta ≤ 125°C)
    Output Current 3 A
    Oscillator Frequency Externally Adjustable: 300 kHz to 2.4 MHz
    Maximum Duty Cycle Min. 93% (fosc = 300 kHz), Min. 67% (fosc = 2.4 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

      * PLLREF pin must not be “OPEN”. When using the Nisshinbo Micro Devices' evaluation board, a pull-down resistor (RPLLREF2: 100 kΩ) is contained on the evaluation board.

    • Efficiency vs. Output Current

      Efficiency vs. Output Current

    • 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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