R1218 Series

PWM Step-up DC/DC Converter for White LED

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Description

The R1218 Series are CMOS-based PWM step-up DC/DC converters, which are optimized to drive white LEDs with constant current. R1218 includes an under-voltage lockout circuit (UVLO), over-voltage protection circuit (OVP). By simply using an inductor, a resistor, and a capacitor (, a diode) as external components, white LEDs can be driven with constant current efficiency. R1218Nxx1A for 2 to 4 lights contains an internal diode while R1218Nxx2A for 5 to 7 lights requires an external diode. The LED current can be determined by the value of current setting resistor. The brightness of the LEDs can be adjusted by applying a PWM signal to the CE or VFB pin.

Spec

	Consumer
Input Voltage Range	1.8 V to 5.5 V (6.5 V)
Operating Temperature Range	-40°C to 85°C (125°C)
Supply Current	Typ. 500 µA
Standby Current	Typ. 0 µA
Output Voltage Range	Externally Adjustable: Max. 30 V
Feedback Voltage	Typ. 0.2 V
Feedback Voltage Accuracy	±10 mV
Oscillator Frequency	Typ. 1.2 MHz
Maximum Duty Cycle	Typ. 91 to 92%
Package	SOT-23-6

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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
R1218Nxxxx-TR-FE		SOT-23-6	R1218N	R1218N-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