R1240x Series

1.2A, 30V Step Down DC_DC converter

Data Sheet / Flyer
Data Sheet * Flyer

The R1240x series are CMOS-based Step-down DC/DC converter with internal Nch high side Tr. (0.35Ω), which can provide the maximum 1.2A output current. The ICs consists of an Oscillator, a PWM control circuit, a Reference Voltage unit, an Error amplifier, phase compensation circuits, a slope circuit, a soft-start circuit, protection circuits, internal voltage regulators, and a switch for boot strap circuit. The ICs can make up a Step-Down DC/DC Converter with the following external components: an inductor, resistors, a diode, and capacitors.

The R1240x series are current mode operating type DC/DC converter which does not require external current sense resistor, and it works high speed response time, high efficiency and compatible with ceramic capacitors. Oscillator frequency is internally set at 1.25MHz.

As a protection function, it has cycle by cycle peak current limit function, short protection function, thermal shutdown function and UVLO.

There are two types for short protection, A version has latch protection function with 2ms delay time, and B version has fold back protection function that keep operating at short condition with lower operating frequency and limiting the Lx current.

Operating Voltage 4.5V~30V
Internal Nch MOSFET Driver Ron=0.35Ω Typ.
Adjustable output voltage with external resistor 0.8V~15V
Feed back voltage 0.8V±1.5%
Peak Current limit function Typ. 2.0A
UVLO function
Operating Frequency 1.25MHz ( 310kHz : fold condition :Ver.B only)
Short protection for output Ver.A: Latch with 2ms delay or Ver.B: Fold Back
Ceramic Capacitor compatible
Stand-by function Typ. 0µA
Package SOT-23-6W, DFN(PLP)2527-10

  • Power source for digital home appliance
  • Power source for hand-held communication equipment, cameras, video instruments such as VCRs,camcorders.
  • Power source for battery-powered equipment.
  • Battery Charger

Data Sheet Flyer Design Guide
R1240x Series R1240x / R1244N Series R1240x Series
Package Info. Mark Info. Quality Assurance Data
SOT-23-6W R1240N Reliability
DFN(PLP)2527-10 R1240K Reliability

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