OUTLINE
The R1224N Series are CMOS-based PWM step-down DC/DC Converter controllers with low supply current.
Each of these ICs consists of an oscillator, a PWM control circuit, a reference voltage unit, an error amplifier, a
phase compensation circuit, a soft-start circuit, a protection circuit, a PWM/VFM alternative circuit, a chip enable
circuit, resistors for output voltage detect, and input voltage detect circuit. A low ripple, high efficiency step-down
DC/DC converter can be easily composed of this IC with only several external components, or a power-transistor,
an inductor, a diode and capacitors. Output Voltage is fixed or can be adjusted with external resistors (Adjustable
types are without PWM/VFM alternative circuit).
With a PWM/VFM alternative circuit, when the load current is small, the operation is automatically switching
into the VFM oscillator from PWM oscillator. Therefore, the efficiency at small load current is improved. Several
types of the R1224Nxxx, which are without a PWM/VFM alternative circuit, are also available.
If the term of maximum duty cycle keeps on a certain time, the embedded protection circuit works. The
protection circuit is Reset-type protection circuit, and it works to restart the operation with soft-start and repeat
this operation until maximum duty cycle condition is released. When the cause of large load current or something
else is removed, the operation is automatically released and returns to normal operation.
Further, built-in UVLO function works when the input voltage is equal or less than UVLO threshold, it makes
this IC be standby and suppresses the consumption current and avoid an unstable operation.
FEATURES
• Supply Current ................................................................Typ. 20μA (R1224Nxx2E/F/M/L, R1224N102M)
Typ. 30μA (R1224Nxx2G, R1224N102G)
Typ. 40μA (R1224Nxx2H, R1224N102H)
• Standby Current ..............................................................Typ. 0μA
• Input Voltage Range .......................................................2.3V~18.5V
• Output Voltage Range.....................................................1.2V to 6.0V (R1224Nxx2x)
1.0V to VIN (R1224N102x)
• Output Voltage Accuracy.................................................±2.0%
• Oscillator Frequency .......................................................Typ. 180kHz (R1224Nxx2M, R1224N102M)
Typ. 300kHz (R1224Nxx2E/G, R1224N102G)
Typ. 500kHz (R1224Nxx2F/H, R1224N102H)
• Efficiency.........................................................................Typ. 90%
• Low Temperature-Drift Coefficient of Output Voltage......Typ. ±100ppm/°C
• Package .......................................................................... SOT-23-5
• Built-in Soft-start Function............................................... Typ. 10ms
• Built-in Current Limit Circuit
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
概述
的r1224n系列是基于CMOS的PWM降压直流/直流转换器控制器具有低电源电流。
这些集成电路包括一个振荡器，一个PWM控制电路，一个参考电压单元，一个误差放大器，一个
相位补偿电路、软启动电路、保护电路、PWM / VFM切换电路，芯片使能
电路、输出电压检测用电阻器和输入电压检测电路。低纹波，高效率降压
直流/直流转换器可以很容易地组成的集成电路只有几个外部元件，或功率晶体管，
电感器、二极管和电容器。输出电压固定或可与外部电阻器调整（可调
类型无PWM / VFM切换电路）。
一个PWM / VFM交流电路，当负载电流小，操作自动切换
从PWM振荡器VFM振荡器。因此，在小负载电流的效率提高。几个
r1224nxxx的类型，这是没有一个PWM / VFM切换电路，也可。
如果占空比保持在一定的时间，嵌入式保护电路工作。这个
保护电路为复位型保护电路，其工作方式为软启动和重复启动操作
此操作直到占空比条件被释放。当负载电流大的原因或某事
否则将自动释放操作并返回正常操作。
此外，内置UVLO功能当输入电压等于或低于UVLO阈值，使
该IC待机和抑制消费电流，避免不稳定的操作。
特征
•电源电流典型值................................................................。20μ一（r1224nxx2e / F / M / L，r1224n102m）
类型.30μ一（r1224nxx2g，r1224n102g）
类型.40μ一（r1224nxx2h，r1224n102h）
..............................................................•待机电流典型值。0μ一
•输入电压范围....................................................... 2.3v ~ 18.5v
•输出电压范围..................................................... 1.2V至6.0v（r1224nxx2x）
1.0V至VIN（r1224n102x）
•输出电压精度.................................................±2%
•振荡器频率.......................................................典型。180khz（r1224nxx2m，r1224n102m）
类型.300khz（r1224nxx2e／g，r1224n102g）
类型.500khz（r1224nxx2f／h，r1224n102h）
•效率.........................................................................典型。90%
•输出电压的低温漂移系数。±100ppm /°C
•包..........................................................................SOT-23-5
•内置软启动功能...............................................类型.10ms
内置电流限制电路
应用
手持通讯设备，照相机•电源、视频设备，如录像机，
摄像机。
•电池供电设备的电源。
•家用电器的电源

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