R1243x Series

30V Input 2A Buck DC/DC Converter

Data Sheet / Flyer
Data Sheet * Flyer
(1.22 MB)    

The R1243x Series is the CMOS-based Step-Down DC/DC Converter with internal Nch high side Tr. (0.175Ω), which can provide the maximum 2A output current. The IC 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 bootstrap circuit. The R1243x Series can make up a Step-Down DC/DC Converter with the following external components: an inductor, resistors, a diode, and capacitors.

The R1243x 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.

There are two types for the oscillator frequency. A/B version's frequency is fixed 1000kHz, and C/D version's frequency is fixed 330kHz.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/C version has latch protection function with 2ms delay time, and B/D version has fold back protection function that keep operating at short condition with lower operating frequency and limiting the Lx current.

The R1243 Series has the built-in soft start time (Typ. 0.4ms). In addition to this, the soft start time is adjustable by adding an external capacitor. The R1243x Series has the FLG pin, which mainly monitors the FB pin voltage and gives the flag output by the Nch open drain if the abnormal condition is detected.

Since the packages for these ICs are HSOP-8E, and DFN(PLP)2527-10, therefore high density mounting of the ICs on boards is possible.

Operating Voltage Range 4.5 V to 30 V
Standby Current Max. 10 µA (VIN = 30 V, CE = L)
Supply Current Typ. 0.7 mA (VIN = 30 V, VFB = 1.0 V)
Output Voltage Range 0.8 V to 18 V, Adjustable with external resistors
Feedback Voltage 0.5 V with 1.4% accuracy
Output Current Max. 2 A*
Peak Current Limiting Typ. 3.8 A
Internal Nch MOSFET Driver Typ. 175 mΩ
Maximum Duty Cycle Min. 85%
Oscillator Frequency Ver. A/B: 1000 kHz, Ver. C/D: 330 kHz
Latch Type Protection Ver. A/C: Typ. 2 ms, Ver. E: 0.08 ms
Fold-back Type Protection Ver. B: 250 kHz, Ver. D: 82.5 kH
Internal Soft-start Time Typ. 0.4 ms, TSS = Open
External Soft-start Time Typ. 12 ms, CSS = 0.1 µF
Flag Output Typ. 0.25 ms, FLG “OFF” delay time
UVLO Released Voltage Typ. 4.0 V
Thermal Shutdown Typ. 160°C, Hysteresis = 35°C
Package HSOP-8E, DFN(PLP)2527-10
  • *)This is an approximate value, because output current depends on conditions and external parts.
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Data Sheet Flyer Package Info. Mark Info. Quality Assurance Data
R1243x Series
(1.22 MB)
R1243x Series HSOP-8E R1243S Reliability
DFN(PLP) 2527-10 R1243K Reliability

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