R1202x Series
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 optimized to drive white LEDs and PMOLED 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 soft-start circuit, and an over-voltage protection
circuit (OVP), a thermal shutdown circuit. By simply using an inductor, divider resistors, and capacitors as external components, PMOLED and
white LEDs can be driven with high efficiency. At the standby mode, the internal NPN transistor can separate the output from the input. (Shutdown
function) The A/B version with auto-discharge function is selectable. D Version can set the LED current with feedback resistor (R1). The brightness
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 (I
DD
) ····························· Typ. 800μA (No switching)
•
Standby Current (I
standby
)······················· Max. 5μA (CE="L")
•
Input Voltage Range (V
IN
) ···················· 2.3V to 5.5V (A/B Version)
•
Feedback Voltage (V
FB
)
•
•
•
•
1.8V to 5.5V (D Version)
······················ 1.0V (A/B Version)
0.2V (D Version)
Feedback Voltage Accuracy ················
±
15mV (A/B Version)
±
10mV (D Version)
Oscillator Frequency (f
osc
)···················· 1.2MHz
Oscillator Maximum Duty Cycle (Maxduty)········ Min. 86%, Typ. 91%
UVLO Detect Voltage (V
UVLO
) ·············· Typ. 2.0V (A/B Version)
Typ. 1.6V (D Version)
•
Coil-current Limit Circuit ·················Current Limit Typ. 350mA
•
Over Voltage Protection Circuit (OVP)
•
Soft Start Time (t
start
) ·······················Typ. 2ms (A/B Version)
•
•
•
•
•
/ Typ. 700mA selectable
Controllable by PWM signal
to the CE pin (D Version)
Thermal Shutdown Circuit ··············Stops at 150°C
Auto-discharge Function·················A Version
Shutdown Function
LED High-speed Dimming Control ·······D Version
Packages ········································DFN1616-6B, TSOT-23-6
BLOCK DIAGRAMS
R1202xxxxA
(With Auto-discharge function, V
FB
=1.0V)
V
FB
V
IN
L
X
V
OUT
UVLO
Error Amp.
PWM Comp.
R
S
Vref
Soft Start
OSC
Slope
Compensation
Current
Limit
Current
Sense
Thermal
Shutdown
Q
Driver
Control
Switch
Control
R1202xxxxB
(Without Auto-discharge function, V
FB
=1.0V)
V
FB
V
IN
L
X
V
OUT
UVLO
Error Amp.
PWM Comp.
R
S
OVP
R1202xxxxD
(Without Auto-discharge function, V
FB
=0.2V)
V
FB
V
IN
L
X
V
OUT
UVLO
Switch
Control
Error Amp.
PWM Comp.
R
S
Vref
OVP
PWM
Cntrl
OSC
EN
Slope
Compensation
Current
Limit
Current
Sense
Thermal
Shutdown
Q
Driver
Control
Switch
Control
Q
Driver
Control
Vref
Soft Start
OSC
Slope
Compensation
Current
Limit
Current
Sense
Thermal
Shutdown
OVP
Shutdown
delay
Chip Enable
Chip Enable
Chip Enable
Σ
Σ
Σ
CE
GND
CE
GND
CE
GND
SELECTION GUIDES
Halogen Free
Part No.
R1202L.x$.1
.∗
-TR
DFN1616-6B 5,000 pcs
R1202L.y$.1
.#
-TR
R1202N.x$.3
.∗
-TR-FE
TSOT-23-6 3,000 pcs
R1202N.y$.3
.#
-TR-FE
Package
Q'ty per Reel
TYPICAL APPLICATIONS
R1202xxxxA/B
L1
10μH to 22μH
C1
1μF
C1
1μF
R1202xxxxD
L1
10μH to 22μH
C2
0.22μF
V
IN
CE
L
X
V
OUT
C3
R2
R3
C2
1μF
V
IN
CE
L
X
V
OUT
.x.
: Specify the OVP voltage.
(.3.) 14V, (.4.) 17V, (.5.) 19V, (.6.) 21V, (.7.) 23V
.y.
: Specify the OVP voltage.
(.3.) 14V, (.7.) 23V
$. : Specify the Coil Current limit.
.
(.1.) Typ. 350mA, (.2.) Typ. 700mA
: (.A.) with auto-discharge function, V
FB
=1.0V.
.∗
(.B.) without auto-discharge function, V
FB
=1.0V.
.#.
: (.D.) without auto-discharge function, V
FB
=0.2V.
GND
V
FB
R1
GND
V
FB
R1
10Ω
TYPICAL CHARACTERISTICS
R1202N713D
5LEDs (10μH)
90
85
80
75
70
65
60
55
50
0
V
IN
=5.0V
V
IN
=4.2V
V
IN
=3.6V
V
IN
=3.0V
PACKAGES (Top View)
DFN1616-6B
6
5
4
Efficiency vs. Output Current
5LEDs (22μH)
90
85
80
75
70
65
60
55
20
TSOT-23-6
6
5
4
Efficiency
η
(%)
∗
1
2
3
1
2
3
Efficiency
η
(%)
1
2
3
CE
V
FB
Lx
4
5
6
GND
V
IN
V
OUT
1
2
3
CE
V
OUT
V
IN
4
5
6
Lx
GND
V
FB
V
IN
=5.0V
V
IN
=4.2V
V
IN
=3.6V
V
IN
=3.0V
∗
)
The tab is substrate level (GND).
5
10
15
Output Current I
OUT
(mA)
50
0
5
10
15
Output Current I
OUT
(mA)
20
APPLICATIONS
•
PMOLED power supply for hand-held equipment
No.EK-255-121001
•
White LED backlight for hand-held equipment
Step-up DC/DC Converter
R1202x Series
R1202x Version Lineup
Product Name
Application
V
FB
Voltage
Input Voltage Range
OVP Voltage
Function
R1202xxxxA/B
PMOLED, General Use
1.0V
2.3V to 5.5V
Select from 14V, 17V, 19V, 21V, 23V
Thermal Shutdown Circuit
Shutdown Function
Auto-discharge Function
1μF to 4.7μF
The Method of Output Voltage Setting
Output Voltage= (R1+ R2) / R1
L1
10μH
C1
1μF
Step-up DC/DC Converter
PWM Step-up DC/DC Converter for White LED/PMOLED and General Use with shutdown function
R1202xxxxD
White LED (Serial drive)
0.2V
1.8V to 5.5V
Select from 14V, 23V
Thermal Shutdown Circuit
Shutdown Function
LED High-speed Dimming Control
0.22μF to 1μF
LED Current setting
When CE pin input is "H" (Duty=100%), LED current can be set
with feedback resistor (R1).
I
LED
=0.2 / R1
C1
1μF
L1
10μH
Output Capacitor
Comment
C2
0.22μF
V
IN
CE
L
X
V
OUT
C3
R2
R3
C2
1μF
V
IN
L
X
CE
V
OUT
GND
V
FB
R1
GND
V
FB
R1
10Ω
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.
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.
I
LED
=Hduty
×
V
FB
/ R1
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.
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
OUT
pin is 34V)
∗)
For detail, please check our website.
The currently available information as of October 2012 is provided in this New Product News.
EK-255-121001
