RICOH R1201N Series PWM Step-up DC DC Converter for White LED User Guide

R1201N Series

PWM Step-up DC/DC Converter for White LED

The R1201N Series are CMOS-based PWM step-up DC/DC converters, which are optimized to drive white LEDs with constant current. R1201N includes a forward diode, an under-voltage lockout circuit (UVLO), and over-voltage protection circuit (OVP). By simply using an inductor, a resistor, and capacitors as external components, white LEDs can be driven with constant current and high efficiently. A diode is built-in; therefore it is possible to drive up to 5 serial LEDs without an external diode. The oscillator frequency can be selected from 1MHz or 1.2MHz. The LED current can be determined by the value of current setting resistor. The brightness of the LEDs can be adjusted quickly by applying a PWM signal (200Hz to 300k Hz) to the CE pin.

FEATURES • Supply Current (IDD) ························Typ. 500μA (1.2MHz, VFB=0V, Lx at no load) • Feedback Voltage Accuracy ···········±10m V

Typ. 450μA (1MHz, VFB=0V, Lx at no load) • Oscillator Frequency (fosc)···············1MHz, 1.2MHz

• Standby Current (Istandby) ·················Max. 5μA (VIN=5.5V,CE="L") • Oscillator Maximum Duty Cycle (Maxduty) ··Typ. 91% • Input Voltage Range (VIN) ···············1.8V to 5.5V (1A/3A Version) • UVLO Detect Voltage (VUVLO)··········Typ. 1.6V

1.8V to 4.5V (2A/4A Version) • Coil-current Limit Circuit ·················Current limit Typ. 700m A

• Absolute maximum rating···············6.5V • Over Voltage Protection Circuit (OVP) • Feedback Voltage (VFB)····················0.2V • Packages········································SOT-23-6 BLOCK DIAGRAMS TYPICAL APPLICATION

VFB VIN LX VOUT L1

Error Amp UVLO C1 PWM Comp. 1μF

R Q Switch

Control VIN LX

Vref Ef fic ie nc PWM OSC Control CE VOUT

Slope Current Current Compensation Protect sense

GND VFB

EN R1

Shutdown Chip Enable delay

CE GND

SELECTION GUIDES

Part No. .xxx : Specify a combination of the oscillator frequercy and OVP voltage.

Halogen Free Package Q'ty per Reel

(.021.) 1.2MHz, 9.5V (.023.) 1MHz, 9.5V

SOT-23-6 3,000 pcs R1201N.xxx A -TR-FE

(.031.) 1.2MHz, 14.0V (.033.) 1MHz, 14.0V (.041.) 1.2MHz, 18.5V (.043.) 1MHz, 18.5V (.051.) 1.2MHz, 20.6V (.053.) 1MHz, 20.6V (.052.)∗ 1.2MHz, 21.6V (.054.) ∗ 1MHz, 21.6V

∗) Input Voltage range:1.8V to 4.5V

PACKAGES TYPICAL CHARACTERISTIC

SOT-23-6 R1201N041A Efficiency vs. LED Current

fosc=1.2MHz

1 CE 2 VOUT

LQH32CN220K53 (3.2x2.5x1.55)

3 VIN VLF3010ST-220 (3.0x2.8x1.0)

4 Lx LQH2MCN220K02 (2.0x1.6x0.9)

5 GND 6 VFB

Output Current IOUT (m A)

APPLICATIONS • White LED driver for hand-held equipment

No.EK-207-120323 Step-up DC/DC Converter