R1245 Series
1.2A 30V Input PWM Step-down DC/DC Converter

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  • Description

    The R1245 Series are 30V input, CMOS-based PWM step-down DC/DC converters featuring 1.2A*output current. R1245 includes a soft start circuit and latch or fold-back protection circuit. By simply using an inductor, resistors, a diode, and capacitors as external components, a high-efficiency step-down DC/DC converter can be easily configured. Due to current mode PWM control, the R1245 provides a fast response and high efficiency. Ceramic output capacitors can be used.

    Compared with R1240, R1245 has a lot of variation of oscillator frequency and can select 330kHz. In case of 330kHz, R1245 can set VOUT lower than R1240. The oscillator maximum duty cycle (Min.) of R1245 is larger than R1240, so it is suitable for low dropout voltage situation. The noise characteristic has been improved rather than R1240, and voltage accuracy is also improved. In addition to HSOP-8E package can be selected, so R1245S is suitable for high power dissipation case.

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

  • Spec
    Consumer Automotive
    Input Voltage Range 4.5 V to 30.0 V (32.0 V)
    Operating Temperature Range -40°C to 105°C (125°C) -40°C to 105°C (150°C)
    Supply Current Typ. 500 µA
    Standby Current Typ. 0 µA
    Output Voltage Range Externally Adjustable: 0.8 V to 27.6 V Externally Adjustable
    (Ver.A/B/C/D) 0.8 V to 27.3 V
    (Ver.E/F) 0.8 V to 25.8 V
    (Ver.G/H) 0.8 V to 21.3 V
    Feedback Voltage 0.8 V
    Feedback Voltage Accuracy ±8 mV
    Feedback Voltage Temperature Coefficient ±100 ppm/°C
    Output Current 1.2 A
    Driver ON-resistance Typ. 0.35 Ω
    Oscillator Frequency 330 kHz (Ver.A/B), 500 kHz (Ver.C/D), 1 MHz (Ver.E/F), 2.4 MHz (Ver.G/H)
    Package DFN(PL)2020-8B, SOT-23-6W, HSOP-8E DFN2020-8, HSOP-8E
    フォールドバック周波数 170 kHz (Ver.B), 170 kHz (Ver.D), 250 kHz (Ver.F), 400 kHz (Ver.H)

    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
    • R1245x00xA/B Typical Application

      R1245x00xA/B Typical Application

      (VOUT=1.2V, VIN=24.0V)

    • R1245x00xA/B Efficiency vs. Output Current

      R1245x00xA/B 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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