R1202x Series
PWM Step-up DC/DC Converter for White LED/PMOLED and General Use with shutdown function
No.EK-255-121001 Step-up DC/DC Converter
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 optimiz ed for the serial drive
of white LED with constant current. The R1202x includes an under-voltage lockout circuit (UV LO), a soft-st a r t 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 LED s can b e driven with high effi cienc y. At t he standby mode, the internal NPN transistor can separate the output f rom 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 brightn ess
of the LEDs a nd the soft-start time can be adjusted by applyin g a PW M signal ( 200Hz to 3 00kHz) to th e CE pin. In addition to DFN1616-6B, 0.95mm
thickness TSOT-23-6 is available.
FEATURES
• Supply Current (IDD)····························· Typ. 800μA
(No switching)
• Standby Current
(I
standby
)
······················· Max. 5μA (
CE="L"
)
• Input Voltage Range (VIN) ···················· 2.3V to 5.5V (A/B Version)
1.8V to 5.5V (D Version)
• Feedback Voltage
(V
FB
)
······················ 1.0V (A/B Version)
0.2V (D Version)
• Feedback Voltage Accuracy ················ ± 15mV (A/B Version)
± 10mV (D Version)
• Oscillator Frequency (fosc)···················· 1.2MHz
•
Oscillator Maximum Duty Cycle (Maxduty)
········ Min. 86%, Typ. 91%
• 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
• Shutdown Function
•
LED High-speed Dimming Control
·······D Version
• Packages········································DFN1616-6B, TSOT-23-6
BLOCK DIAGRAMS
R1202xxxxA
(With Auto-discharge functio n, VFB=1.0V)
Σ
Error Amp.
PWM Comp.
Vref
Soft Start Thermal
Shutdown
OSC
Slope
Compensation
V
FB
V
IN
L
X
V
OUT
GND
R Q
S
UVLO
Current
Limit
OVP
Drive
r
Control
Switch
Control
Chip Enable
CE
Current
Sense
R1202xxxxB
(Without Auto-discharge function, VFB=1.0V)
Σ
Error Amp.
PWM Comp.
Vref
Soft Start Thermal
Shutdown
OSC
Slope
Compensation
V
FB
V
IN
L
X
V
OUT
GND
RQ
S
UVLO
Current
Limit
OVP
Driver
Control
Switch
Control
Chip Enable
CE
Current
Sense
R1202xxxxD
(Without Auto-discharge function, VFB=0.2V)
Σ
Error Amp.
PWM Comp.
Vref
OSC
Slope
Compensation
V
FB
V
IN
L
X
V
OUT
GND
R Q
S
UVLO
Current
Limit
OVP
Drive
r
Control
Thermal
Shutdown
Switch
Control
Chip Enable
CE
Current
Sense
Shutdown
delay
PWM
Cntrl EN
SELECTION GUIDES TYPICAL APPLICATIONS
Halogen Free
Package
Q'ty per Reel
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
.
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, VFB=1.0V
.
(
.
B
.
)
without auto-discharge function, VFB=1.0V
.
.
#
.
: (
.
D
.
)
without auto-discharge function, VFB=0.2V
.
R1202xxxxA/B
C1
V
IN
L
X
CE
GND
1
μ
F
L1
10
μ
H to 22
μ
H
C2
1
μ
F
R1
V
OUT
V
FB
R2 R3
C3
R1202xxxxD
C1
V
IN
L
X
CE
GND
1
μ
F C2
0.22
μ
F
R1
10
Ω
V
OUT
V
FB
L1
10μH to 22μH
PACKAGES (Top View)
DFN1616-6B TSOT-23-6
6 5 4
1 2 3
∗
65 4
12 3
1 CE
2 VFB
3 Lx
4 GND
5 VIN
6 VOUT
∗)
The tab is substrate level (GND).
1 CE
2 VOUT
3 VIN
4 Lx
5 GND
6 VFB
APPLICATIONS
• PMOLED power supply for hand-held equipment • White LED backlight for hand-held equipment
TYPICAL CHARACTERISTICS
R1202N713D Efficiency vs. Output Curren t
5LEDs
(
10μH
)
0 5 10 15 20
Output Current I
OUT
(mA)
Efficiency η (%)
50
90
80
85
70
60
75
65
55
V
IN
=5.0V
V
IN
=4.2V
V
IN
=3.6V
V
IN
=3.0V
5LEDs (22μH)
0 5 10 15 20
Output Current I
OUT
(mA)
Efficiency η (%)
V
IN
=5.0V
V
IN
=4.2V
V
IN
=3.6V
V
IN
=3.0V
50
90
80
85
70
60
75
65
55
R1202x Series Step-up DC/DC Converter
PWM Step-up DC/DC Converter for White LED/PMOLED and General Use with shutdown function
The currently available information as of October 2012 is provided in this New Product News. EK-255-121001
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
Thermal Shutdown Circuit
Shutdown Function
LED High-speed Dimming Control
Output Capacitor 1μF to 4.7μF 0.22μF to 1μF
Comment The Method of Output Vol tage Setting
Output Voltage= (R1+ R2) / R1
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 Current setting
When CE pin input is "H" (Duty=100%), LED current can be set
with feedback resistor (R1).
ILED=0.2 / R1
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.
ILED=Hduty × VFB / 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 VOUT pin is 34V)
∗) For detail, please check our website.
C1
VIN LX
CE
GND
1μF
L1
10μH
C2
1
μ
F
R1
VOUT
VFB
R2 R3
C3
C1
VIN LX
CE
GND
1μF
L1
10μH
C2
0.22
μ
F
R1
10Ω
VOUT
VFB
