RICOH R1205x Series PWM Step-up DC DC Converter for White LED, PMOLED and General Use Data Manual
Summary
The R1205x Series is an advanced CMOS PWM step-up DC/DC converter, optimized for driving white LEDs and PMOLEDs with high efficiency and constant current. This manual serves as a comprehensive guide for electronics engineers and designers, detailing reliable system implementation. It covers hardware specifications, operational modes (A and B versions), built-in protections like UVLO and OVP, and detailed application guidelines. Use this resource to design stable, dimmable, and highly efficient LED power supplies ranging from deep cycle battery operation (2.3V) up to 5.5V.
Page 1 Text Content
R1205x Series
PWM Step-up DC/DC Converter for White LED/PMOLED and General Use
The R1205x Series are CMOS-based PWM step-up DC/DC converters, which are optimized to drive white LEDs with constant current. There are two types. The A versions are optimized for the general use, and the B version is optimized for the serial drive of white LED with constant current. The R1205x includes a forward diode, an under-voltage lockout circuit (UVLO), a soft-start circuit, and an over-voltage protection circuit (OVP), a thermal shutdown circuit. By simply using an inductor, divider resisters, and capacitors as external components, white LEDs can be driven with high efficiently. B version can set LED current with feedback resister (R1). The brightness of the LEDs and the soft-start time can be adjusted by applying a PWM signal (200Hz to 300k Hz) to the CE pin. In addition to DFN1616-6B, 0.95mm thickness TSOT-23-6 is available.
FEATURES • Supply Current (IDD) ························Typ. 800μA (VIN= 5.5V, VFB = 0V, Lx at no load) • UVLO Detect Voltage (VUVLO)·······Typ. 2.0V (A Version) • Standby Current (Istandby)··················Max. 5μA (VIN= 5.5V, VCE = 0V) Typ. 1.6V (B Version) • Input Voltage Range (VIN) ···············2.3V to 5.5V (A Version) • Coil-current Limit Circuit ··············Current Limit Typ. 350m A
1.8V to 5.5V (B Version) / Typ. 700m A selectable
• Feedback Voltage (VFB) ·················1.0V (A Version) • Over Voltage Protection Circuit (OVP) Typ.25V
0.2V (B Version) • Soft Start Time (tstart) ····················Typ. 2ms (A Version)
• Feedback Voltage Accuracy ···········± 1.5% (A Version) Controllable by PWM signal
± 10m V (B Version) to the CE pin (B Version)
• Oscillator Frequency (fosc)···············1.2MHz • Thermal Shutdown Circuit ···········Stops at 150°C • Oscillator Maximum Duty Cycle (Maxduty)···Typ. 91% • Packages ·····································DFN1616-6B, TSOT-23-6
ffi ci en cy
BLOCK DIAGRAMS R1205x8xx A R1205x8xx B
VFB VIN LX VOUT VFB VIN LX VOUT
Error Amp. UVLO Error Amp. UVLO
PWM Comp. PWM Comp.
R Q Driver Driver Control Control
Vref Vref
OSC OVP PWM OSC OVP Soft-start Cntrol EN
Slope Current Current Thermal Slope Current Current Thermal Compensation Limit sense Shutdown Compensation Limit sense Shutdown
Shutdown delay
Chip Enable Chip Enable
CE ffi ci en cy GND CE GND
SELECTION GUIDES TYPICAL APPLICATIONS
Halogen Free Package Q'ty per Reel Part No. R1205x8xx A R1205x8xx B L1
DFN1616-6B 5,000 pcs R1205L8 .x.1.∗ -TR 10μH
TSOT-23-6 3,000 pcs R1205N8x.3.∗ -TR-FE C1
.x. : Specify the Coil Current limit. 0.22μF
VIN LX
VIN LX
(1) Typ. 350m A, (2) Typ. 700m A .∗ : Specify the feedback voltage. CE VOUT
CE VOUT
GND VFB
GND VFB R1
L1：LQH32CN100K53
L1：LQH32CN100K53
C1：CM105B105K06
C1：CM105B105K06
C2：GRM21BR11E224KA01
C2：GRM31BR11E105KA01
PACKAGES (Top View) TYPICAL CHARACTERISTIC DFN1616-6B TSOT-23-6 Efficiency vs. LED Output Current 6 5 4 6 5 4
VOUT=10V (10μF) 6LEDs (10μF)
1 CE 4 GND 1 CE 4 LX 2 VFB 5 VIN 2 VOUT 5 GND
3 LX 6 VOUT 3 VIN 6 VFB Vin=3V
Vin=3.6V Vin=3V Vin=3.6V
Vin=4.2V Vin=4.2V
∗) The tab is substrate level (GND).
Vin=5V Vin=5V
Output Current (m A) Output Current ILED (m A)
APPLICATION • OLED power supply for hand-held equipment • White LED backlight for hand-held equipment No.EK-272-120326 Step-up DC/DC Converter
Page Summary Contents For RICOH R1205x Series PWM Step-up DC DC Converter for White LED, PMOLED and General Use Data Manual
Manual Details
| Brand | Ricoh |
|---|---|
| Pages | 2 |
| File Size | 301.82 KB |
| Published | June 04, 2026 |
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Frequently Asked Questions
What are the primary functions included in the R1205x converter?
It includes a forward diode, UVLO, soft-start, OVP, thermal shutdown, and coil-current limit circuits.
How can I adjust the LED brightness or dimming level?
Apply a PWM signal (200Hz to 300kHz) to the CE pin. Higher frequencies are recommended for better performance.
Is there a difference between the A and B versions of R1205x?
Yes, Version A is optimized for general use, while Version B is specifically designed for serial driving of white LEDs with constant current.
What input voltage range does the converter support?
The A version supports 2.3V to 5.5V, and the B version supports 1.8V to 5.5V.