Ricoh R1243X Manuals

The R1243x series is a 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 controller's I/O port.

The R1243x Series is a 30V input, CMOS-based PWM step-down DC/DC converter with 2A∗ output current. R1243x includes a soft start circuit and a latch or fold-back protection circuit. A high-efficiency step-down DC/DC converter can be easily configured by using an inductor, resistors, a diode, and capacitors as external components. The R1243x provides a fast response and high efficiency due to current mode PWM control. Ceramic output capacitors can be used.