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R1225 Series
18.5V Input PWM/VFM Step-down DCDC Controller

Product Specifications

The R1225 Series are low supply current CMOS-based PWM/VFM controlled step-down DC/DC controllers with an external output transistor. By simply using a power transistor, an inductor, a diode, and a capacitor as external components, a high-efficiency step-down DC/DC converter can be easily configured. The PWM/VFM alternative circuit automatically switches to VFM control in the smaller output current range and provides high efficiency even in the smaller output current range. The version with fixed PWM control is also available.

The latch type protection circuit embedded into the device latches the power MOS in the "OFF" state when the oscillator maximum duty cycle continues for a predetermined period of time. Protection time is adjustable by the capacity of an external capacitor of the DLY pin.
R1225 also includes an under-voltage lockout circuit (UVLO) that stops DC/DC operation and prevents malfunction when the supply voltage falls below the UVLO detector threshold and reduces supply current.

FEATURES

Input Voltage Range (Maximum Rating) 2.3 V to 18.5 V (20.0 V)
Supply Current Typ. 20 µA (R1225Nxx2A/B/J/K)
Typ. 30 µA (R1225Nxx2C)
Typ. 40 µA (R1225Nxx2D)
Standby Current Typ. 0.0 µA
Oscillator Frequency 180 kHz, 300 kHz, 500 kHz
Efficiency Typ. 90%
Output Voltage Range 1.2 V to 6.0 V (0.1 V steps)
Output Voltage Accuracy ±2.0%
Temperature-Drift Coefficient of Output Voltage Typ. ±100 ppm/°C
Soft Start Time Typ. 10 ms
Latch-type Protection Function Delay time for protection
Typ. 20 ms

APPLICATION INFORMATION

R1225Nxx2x

L: 27µH, C1: 10µF, C2: 0.1µF, C3: 47µF, C4: 0.02µF, R1: 10Ω

TYPICAL CHARACTERISTICS

R1225N332A Efficiency vs. Output Current

PIN DESCRIPTION

SOT-23-6w2.9 mm × 2.8 mm

SOT-23-6W

1 EXT
2 VIN
3 DLY
4 CE
5 GND
6 VOUT

R1225 Series for Consumer

APPLICATIONS

  • Power source for hand-held communication equipment, cameras, video instruments such as VCRs, camcorders
  • Power source for battery-powered equipment
  • Power source for household electrical appliances

SELECTION GUIDE

In the R1225 Series, the output voltage, and the optional function for the ICs can be selected at the user's request.

Product Name   Package Quantity per Reel
R1225Nxx2#−TR-FE Consumter SOT-23-6W 3,000
  • xx … The output voltage can be designed in the range from 1.2V(12) to 6.0V(60) in 0.1V steps.
  • # … The oscillator frequency and the modulation method are options as follows.
    A : 300kHz, PWM/VFM
    B : 500kHz, PWM/VFM
    C : 300kHz, fixed PWM
    D : 500kHz, fixed PWM
    J : 180kHz, PWM/VFM
    K : 180kHz, fixed PWM

DOCUMENT/CONTACT

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Technical Support

Package *1 Marking Reliability *2
SOT-23-6W R1225N R1225N (-FE)

*1: The package file includes package dimensions, taping specifications, taping reels dimensions, power dissipations, and land pattern (foot pattern).
*2: Reliability file includes a reliability test report and a reflow profile.

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