R1285L Series
PWM Step-up/Inverting DC/DC Converter for AMOLED
The R1285L Series are dual output CMOS-based PWM step-up/inverting DC/DC converters. R1285L includes a soft start circuit, an
under-voltage lockout circuit (UVLO) and a latch type protection circuit. By simply using inductors, (resistors), capacitors, and
diodes as external components, a high-efficiency step-up/inverting DC/DC converter can be easily configured. The Inverting DC/DC
converter can be started after Step-up DC/DC converter by sequence control. At the standby mode, the internal shutdown switch can
separate the output from the input.
FEATURES
•
Supply Current (I
DD1
)························ Typ. 4mA (V
IN
=4.8V, In switching)
•
Supply Current (I
DD2
)························ Typ. 350μA (V
IN
=4.8V, In non-switching)
•
Standby Current (I
standby
) ·················· Max. 3μA (V
IN
=4.8V, CE="L")
•
Input Voltage Range (V
IN
) ················ 2.3V to 4.8V
•
Step-up Output Voltage Range (V
OUTP
)····· Select from 4.6V, 4.8V or 5.0V
•
Inverting Output Voltage Range (V
OUTN
)···· -2.0V to -6.0V (A Version)
•
•
The output voltage : adjustable up to -6V
with an external resistor.
(Feedback voltage : 0V) (B Version)
Step-up Output Voltage Accuracy····
±
1.5%
Inverting Output Voltage Accuracy ··
±
1.5% (A Version)
±
25mV (B Version)
•
Output Reference Voltage (V
REF
) ······· 1.2V (± 28mV)
•
Oscillator Frequency (f
osc
)···················· 1.4MHz
•
Oscillator Maximum Duty Cycle (Maxduty)···· Step-up :Typ. 85%
•
UVLO Detect Voltage (V
UVLO
)··············· Typ. 2.05V
•
Soft Start Time (t
start
) ···························· Typ. 4.5ms
•
Latch Protection Circuit ······················· Delay time for protection
•
Auto-Discharge function
•
Package··············································· DFN2730-12
Typ. 50ms
Inverting :Typ. 90%
BLOCK DIAGRAMS
R1285LxxxA
(Fixed Inverting output voltage type)
PV
CC
Current
Limit
PWM
Control
OSC
Maxduty
PWM
Control
Timer
Short
Protect
Discharge
Control
Current
Limit
R1285L00xB
(Adjustable inverting output voltage type)
PV
CC
Current
Limit
PWM
Control
OSC
Maxduty
PWM
Control
Timer
Short
Protect
Discharge
Control
Current
Limit
L
XP1
L
XP2
L
XP1
L
XP2
L
XN
V
OUTN
Maxduty
L
XN
Maxduty
PGND
V
OUTP
V
OUTN
V
FBN
Discharge
Control
PGND
V
OUTP
Discharge
Control
TEST1
TEST2
Vref3
Vref2
Sequence
Control
UVLO
Vref1
Soft Start1
V
REF
Vref3
Vref2
Sequence
Control
UVLO
Vref1
Soft Start1
Soft Start2
Enable
Control
Soft Start2
CE
V
CC
GND
CE
Enable
Control
V
CC
GND
SELECTION GUIDE
Halogen Free Package Q'ty per Reel
Part No.
-
DFN2730-12 5,000 pcs R1285L.xx$..
∗
-TR-F
.xx.
: Specify the inverting output voltage within the range of
-2.0V (.20.) to -6.0V (.60.) in 0.1V steps. For the adjustable
inverting output voltage type (.00.). (B Version)
.$.
: Select the step-up output voltage from
(.1.) 4.6V, (.2.) 4.8V or (.3.) 5.0V.
.
∗
.
: Select from (.A.) Fixed Inverting output voltage type or
(.B.) Adjustable inverting output voltage type
TYPICAL APPLICATIONS
R1285LxxxA
V
OUTP
D1
PGND
V
OUTP
PV
CC
V
CC
C1
4.7μF
GND
CE
CE control
L
XP2
L1
L
XP1
L2
L
XN
D2
V
OUTN
TEST1
TEST2
C2
10μF
V
OUTN
C3
10μF
R1285L00xB
V
OUTP
D1
PGND
V
OUTP
PV
CC
V
CC
GND
CE
CE control
L
XP2
L1
L
XP1
L2
L
XN
D2
C1
4.7μF
V
OUTN
R2
V
FBN
R1
V
REF
C5
C4
R3
C2
10μF
V
OUTN
C3
10μF
(Fixed Inverting output voltage type) (Adjustable inverting output voltage type)
L1,L2: VLF3010-4R7 (TDK)
SD: CRS02 (Toshiba)
L1,L2 : VLF3010-4R7 (TDK)
SD : CRS02 (Toshiba)
R1, R2: Resistors for setting V
OUTN
R3: 2kΩ,C4: 47pF, C5: 0.1μF
PACKAGE
DFN2730-12
Top View
12 11 10 9
8
7
TYPICAL CHARACTERISTIC
Bottom View
7
8
9 10 11 12
Efficiency vs. Output Current
R1285Lxx1A/001B
R1285L49xA/00xB
100
90
80
70
60
50
40
30
20
0
V
IN
=4.5V
V
IN
=3.7V
V
IN
=2.9V
20 40 60 80 100 120 140 160 180 200
I
OUTP
(mA)
V
OUTP
=4.6V, I
OUTN
=0mA,Topt=25
°C
100
90
Efficiency
η
(%)
∗
V
OUTN
=-4.9V, I
OUTP
=0mA,Topt=25
°C
1
2
3
4
5
6
6
5
4
3
2
1
1
2
3
4
5
6
PGND
V
OUTP
PV
CC
V
CC
GND
CE
7
8
9
10
11
12
TEST2 or V
REF
2
TEST1
∗
or V
FBN
V
OUTN
L
XN
L
XP1
L
XP2
∗
2
Efficiency
η
(%)
80
70
60
50
40
30
20
0
V
IN
=4.5V
V
IN
=3.7V
V
IN
=2.9V
20 40 60 80 100 120 140 160 180 200
I
OUTN
(mA)
∗
) The tab is substrate level (GND).
∗
2) The TEST1 pin and TEST2 pin connected to the GND level or should be open.
APPLICATIONS
•
Power source for active matrix OLED
No.EK-208-101001
•
Power source for battery-powered equipment
Step-up/Inverting DC/DC Converter
1. The products and the product specifications described in this document are subject to change or
discontinuation of production without notice for reasons such as improvement. Therefore, before
deciding to use the products, please refer to Ricoh sales representatives for the latest
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example application circuits for the products. The release of such information is not to be
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concerning the products or the technical information.
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