RICOH R1202x User Manual

R1202x Series

y

μ

μ

PWM Step-up DC/DC Converter for White LED / PMOLED and General Use with shutdown function

The R1202x Series are CMOS-based PWM step-up DC/ DC converters, which are opti mized to drive white LEDs and OLED with constant
current. There are two types. The A/B versions are optimized for the general use or the drive of PMOLED, and the D version is optimized
for the serial drive of white LED with constant current. The R1202x includes an under-voltage lockout circuit (UVLO), a s oft-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, OLED and white LEDs can be driven with high efficien tly. At the standby mode, the internal NPN transistor can
separate the output from the input. (Shutdown function) The A/B version with auto-discharge functio n is selectable. D Version can set
white LED current with feedback resister (R1). The brig htness of the LEDs and the soft-start time can be adjusted by applying a PWM
signal (200Hz to 300kHz) to the CE pin. In addition to DFN1616-6B, 0.95mm thickness TSOT-23-6 is available.

FEATURES

• Supply Current (IDD)························ Typ. 800μA

• Standby Current

(I

standby

)

··················Max. 5μA (

• Input Voltage Range (VIN) ··············· 2.3V to 5.5V (A/B Version)

• Feedback Voltage

(VFB)

·················1.0V (A/B Version)

1.8V to 5.5V (D Version)

0.2V (D Version)

• Feedback Voltage Accuracy··········· ± 1.5% (A/B Version)

• Oscillator Frequency (fosc)···············1.2MHz

± 10mV (D Version)

•

Oscillator Maximum Duty Cycle (Maxduty)

···Typ. 91%

BLOCK DIAGRAMS

(VIN= 5.5V, V

VIN= 5.5V, V

FB

= 0V, Lx at no load)

CE

= 0V

)

• UVLO Detect Voltage (VUVLO)···Typ. 2.0V (A/B Version)

Typ. 1.6V (D Version)

• Coil-current Limit Circuit ··········Current Limit Typ. 350mA

/ Typ. 700mA selectable

• Over Voltage Protection Circuit (OVP)

• Soft Start Time (tstart) ················Typ. 2ms (A/B Version)

Controllable by PWM signal
to the CE pin (D Version)

• Thermal Shutdown Circuit ·······Stops at 150°C

• Auto-Discharge function ··········A Version

• Packages································· DFN1616-6B, TSOT-23-6

R1202xxxxA

(With Auto-Discharge function, VFB=1.0V)

V

FB

Error Amp.

Vref

Soft Start

Chip Enable

CE

SELECTION GUIDES TYPICAL APPLICATIONS

Halogen Free

.x. :

.y.

: Specify the OVP voltage.
(3
.$.

: Specify the Coil Current limit.
(1

: (.A.)

.∗

(.B.)

: (.D.)

#

Package

DFN1616-6B

TSOT-23-6

Specify the OVP voltage.

(3) OVP : 14V, (4) OVP : 17V, (5) OVP : 19V, (6) OVP : 21V
(7) OVP : 23V

) OVP : 14V, (7) OVP : 23V

) Typ. 350mA, (2) Typ. 700mA

with auto-discharge function, VFB=1.0V
without auto-discharge function, VFB=1.0V
without auto-discharge function, VFB=0.2V

PACKAGES (Top View) TYPICAL CHARACTERISTIC

DFN1616-6B TSOT-23-6

6 5 4

1 2 3

1 CE 4 GND
2 VFB 5 VIN
3 LX 6 VOUT

The tab is substrate level (GND).

)

∗

PWM Comp.

R Q

S

OSC

Slope

Compensation

Σ

∗

V

IN

UVLO

Driver

Control

Current

Limit

Q'ty per Reel

5,000 pcs

3,000 pcs

L

X

Current
Sense

GND

Switch

Control

Thermal

Shutdown

V

OUT

OVP

R1202L .x$.1.∗ -TR
R1202L .y$1.#-TR
R1202N
R1202N

1 CE 4 LX
2 VOUT 5 GND
3 VIN 6 VFB

(Without Auto-Discharge function, VFB=1.0V)

V

FB

Error Amp.

Vref

Soft Start

Chip Enable

Part No.

.x$.3.∗

-TR-FE

.y$.3.#

-TR-FE

.

.

.

6 5 4

1 2 3

PWM Comp.

CE

R1202xxxxB

V

IN

L

X

UVLO

Driver

RQ

Control

S

OSC

Slope

Current

Compensation

Limit

Σ

C1
1μF

90

85

80

75

70

65

Efficiency (%)

60

55

50

0 5 10 15 20

Switch

Control

Current

Thermal

Sense

Shutdown

GND

R1202xxxxA/B

L1

H

10

V

IN

L

X

CE

V

OUT

V

GND

FB

R1202N713D Efficiency vs. LED Output Current

4LEDs

Output Current ILED (mA)

V

OUT

OVP

(

10μF

(Without Auto-Discharge function, VFB=0.2V）

V

FB

Error Amp.

Vref

PWM

EN

Cntrl

Shutdown

dela

Chip Enable

C3

R2

R3

R1

CE

C2

F

1

)

Vi n=3V
Vi n=3. 6V
Vi n=4. 2V
Vi n=5V

R1202xxxxD

V

IN

L

X

R Q

S

OSC

Slope

Compensation

Σ

UVLO

Driver

Control

Current

Limit

PWM Comp.

R1202xxxxD

V

IN

CE

GND

L1
10μH

V

C1
1μF

5LEDs (10μF)

90

85

80

75

70

65

Eff icien cy (%)

60

55

50

0 5 10 15 20

Ou tpu t C urr ent ILED (mA )

Switch

Control

Current

Thermal

Sense

Shutdown

GND

L

X

OUT

V

FB

R1
10Ω

V

OUT

OVP

Vin=3V
Vin=3.6V
Vin=4.2V
Vin=5V

C2

0.22μF

APPLICATIONS

• OLED power supply for hand-held equipment • White LED backlight for hand-held equipment

No.EK-255-111001 Step-up DC/DC Converter

R1202x Series Step-up DC/DC Converter

μ

μ

PWM Step-up DC/DC Converter for White LED / PMOLED and General Use with shutdown function

R1202x Version Lineup

Product Name R1202xxxxA/B R1202xxxxD
Application PMOLED, General Use White LED (Serial drive)
VFB Voltage 1.0V 0.2V
Input Voltage Range 2.3V to 5.5V 1.8V to 5.5V
OVP Voltage Select from 14V, 17V, 19V, 21V, 23V Select from 14V, 23V
Function Thermal Shutdown Circuit

Shutdown Function
Auto-Discharge Function

Output Capacitor 1μF to 4.7μF 0.22μF to 1μF
Comment The Method of Output Voltage Setting

Output Voltage= (R1+ R2) / R1

C1
1μF

L1
10μH

VIN LX

CE

VOUT

GND

VFB

C3

C2
1

R2

R1

F

R3

The total value of R1 and R2 should be equal or less
than 300kΩ.
Voltage rating of capacitor (C2) is recommended to
use 1.5 times or more the output setting voltage.

Soft-Start Time

The soft start time is set to Typ. 2ms within the IC.

In case of 6 lights or more, we recommends the R1205x Series and R1218x Series*.
More than 5 lights of R1218x Series requires an external diode and OVP Voltage is set up to 31.5V. (Maximum rating of V

∗) For detail, please check our website.

Thermal Shutdown Circuit
Shutdown Function

LED Current setting

When CE pin input is "H" (Duty=100%), LED current can be set
with feedback resistor (R1).

LED=0.2 / R1

I

C1

1μF

L1
10μH

VIN LX

CE

VOUT

C2

0.22

F

GND

VFB

R1
10Ω

LED Dimming Control

The LED brightness can be controlled by inputting the PWM
signal to the CE pin. The current of LEDs when High-Duty of the
CE input is ”Hduty” reaches the value as in next formula.

LED=Hduty × VFB / R1

I

The frequency of the PWM signal is using the range between
200Hz to 300kHz. When controlling the LED brightness by the
PWM signal of 20kHz or less, the increasing or decreasing of
the inductor current might be make a sounds in the hearable
sound wave area. In that case, please use the PWM signal in
the high frequency area.

OUT pin is 34V)

The currently available information as of October 2011 is provided in this New Product News.

EK-255-111001