R1273 Series
14A 34V Input Step-down DC/DC Converter with Synchronous Rectifier

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  • Description

    The R1273 is a step-down DC/DC converter which can generate an output voltage of 0.7 V to 5.3 V by driving high- / low-side NMOSs. By the adoption of a unique current mode PWM architecture without an external current sense resistor, the R1273 can make up a stable DC/DC converter with high-efficiency even if adding low Ron MOSFETs and a low DCR inductor externally. And, by the frequency characteristics optimization with using external phase compensation capacitor, the R1273 can achieve a high-speed response to variations of input voltage and load current. The user-settable oscillation frequency is adjustable over a range of 250 kHz to 1 MHz by external resistors, and also can be synchronized to an external clock in a range of 250 kHz to 1 MHz. The R1273 supports three operating modes: Forced PWM mode, PLL_PWM mode, and PWM/VFM Auto-switching mode. These modes are selectable according to conditions of the MODE pin. Especially, the PWM/VFM Auto-switching mode can improve efficiency under light load conditions.

    The R1273 can minimize the output voltage drop caused by an input voltage drop at cranking, with reducing the operating frequency (the lowest possible limit is a quarter of the frequency) so that the off-duty is reduced.

    Protection functions include a current limit function, a hiccup-mode short-circuit protection (non-latch type), a thermal shutdown function, an UVLO (Under Voltage Lock Out) function, an OVD (Over Voltage Detection) function, a soft-start function, a low-inductor current shutdown function, and so on. Also, a power good function provide the status of output with using a power good (PGOOD) pin.

    For EMI reduction, SSCG (Spread-Spectrum Clock Generator) for diffused oscillation frequency at the PWM operation is optionally available. The R1273 is available in QFN0505-32B package.

  • Spec
    Consumer Industrial Automotive
    Input Voltage Range 4.0 V to 34.0 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. 15 µA
    Standby Current Typ. 3 µA
    Start-up Voltage 4.5 V
    Output Voltage Range Externally Adjustable: 0.7 V to 5.3 V
    Feedback Voltage 0.64 V
    Feedback Voltage Accuracy ±1%
    Driver ON-resistance High-side: Typ. 11.8 mΩ / Low-side: Typ. 12.3 mΩ
    Oscillator Frequency Externally Adjustable: 250 kHz to 1 MHz
    Package QFN0505-32B

    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 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.

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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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