R1224 Series

18.5V Input PWM/VFM Step-down DC/DC Controller

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Description

The R1224 Series are low supply current CMOS-based PWM/VFM step-down DC/DC controller 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 and adjustable output voltage with an external resistor is also available.

The reset type protection circuit embedded into the device limits output current by repeatedly triggering the soft start circuit when the oscillator maximum duty cycle continues for a predetermined period of time. When the oscillator maximum duty cycle ends, normal operation is resumed automatically. R1224 also includes an under-voltage lockout circuit (UVLO) that stops DC/DC operation and prevents malfunction when the supply voltage falls below the UVLO detect voltage and reduces supply current.

Spec

	Consumer
Input Voltage Range	2.3 V to 18.5 V (20.0 V)
Operating Temperature Range	-40°C to 85°C (125°C)
Supply Current	Typ. 20 µA (R1224Nxx2E/F/L/M、R1224N102M) Typ. 30 µA (R1224Nxx2G、R1224N102G) Typ. 40 µA (R1224Nxx2H、R1224N102H)
Standby Current	Typ. 0 µA
Output Voltage Range	Internally Fixed Ver.: 1.0 V to 6.0 V (0.1 V step) Externally Adjustable Ver.: 1.0 V to VIN
Output Voltage Accuracy	±2% (Ta = 25°C)
Output Voltage Temperature Coefficient	Typ. ±100 ppm/°C
Oscillator Frequency	Typ. 180 kHz (R1224Nxx2L/M、R1224N102M) Typ. 300 kHz (R1224Nxx2E/G、R1224N102G) Typ. 500 kHz (R1224Nxx2F/H、R1224N102H)
Efficiency	Typ. 90%
Package	SOT-23-5

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TSD	ILX	OCP	OVP	UVLO	OVLO	Reverse	Shutdown	Soft Start	SSCG	PGOOD	Auto Discharge	Anti-ringing	Sequencing	Max Duty	Ext. Phase	LED Adjust

Functional Description

Quality &
Packages

Product Name	Compatibility	Package	Marking	Reliability
R1224Nxx2x-TR-FE		SOT-23-5	R1224N	R1224N-FE

Refer to the datasheets for the details on the product.
The package file or the datasheet includes package dimensions, taping specifications, taping reels dimensions, power dissipations, and recommended land pattern.

TSD	Thermal Shutdown Function
ILX	LX Current Limit Function
OCP	Overcurrent Protection
OVP	Overvoltage Protection
UVLO	Undervoltage Lockout Protection
OVLO	Overvoltage Lockout Protection
Reverse	Reverse Current Protection Circuit
Shutdown	Shutdown Function
Soft Start	Soft Start Function
SSCG	Spread Spectrum Clock Generator Function
PGOOD	Power Good Output
Auto Discharge	Auto Discharge Function
Anti-ringing	Anti-ringing Switch Function
Sequencing	Start-up Sequencing Control
Max Duty	Maximum Duty Cycle
Ext. Phase	Externally Adjustable Phase Compensation
LED Adjust	LED High-speed Dimming Control