R1285L201A-TR [RICOH]
Switching Regulator, 1.9A, 1600kHz Switching Freq-Max, PDSO12, 2.70 X 3 MM, HALOGEN AND LEAD FREE, DFN-12;
| 型号： | R1285L201A-TR |
| 厂家： | 
RICOH ELECTRONICS DEVICES DIVISION |
| 描述： | Switching Regulator, 1.9A, 1600kHz Switching Freq-Max, PDSO12, 2.70 X 3 MM, HALOGEN AND LEAD FREE, DFN-12 开关 光电二极管 |
| 文件： | 总24页 (文件大小：704K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
R1285L series
Non-promotion
2ch DCDC for OLED
NO.EA-208-130509
OUTLINE
The R1285L 2ch DC/DC converter is designed for OLED Display power source. It contains a step up DC/DC
converter and an inverting DC/DC converter to generate two required voltages by OLED Display.
Step up DC/DC converter generates boosted output voltage to 4.6V ~ 5.0V. Inverting DC/DC converter generates
negative voltage –2.0V ~ -6.0V independently. Each of the R1285 series consists of an oscillator, a PWM control
circuit, a voltage reference, error amplifiers, over current protection circuits, short protection circuits, an under
voltage lockout circuit (UVLO), a complete shutdown switch and an Nch driver for boost operation, a Pch driver for
inverting. A high efficiency boost and inverting DC/DC converter can be composed with external inductors, diodes,
capacitors and resistors. Start up sequence is internally made.
FEATURES
z
z
Operating Voltage • • • • • 2.3V ~ 4.8V
Step Up DC/DC (CH1)
Internal Pch MOSFET for complete shutdown (Ron=300mΩTyp.)
Internal Nch MOSFET Driver (Ron=300mΩTyp.)
Output Voltage (VOUTP
) • • • • • 4.6V ~ 5.0V (0.2VStep)
Auto Discharge function for positive output
Internal Soft start function (Typ. 4.5ms)
Over Current Protection
Maximum Duty Cycle: 85%(Typ.)
z
z
z
Inverting DC/DC (CH2)
Internal Pch MOSFET Driver (Ron=600mΩ Typ.)
Output Voltage (VOUTN
Adjustable Vout Up to -6V with external resistors
Auto Discharge function for negative output
Internal Soft start function (Typ. 4.5ms)
Over Current Protection
)
• • • • • -2V ~ -6V (0.1VStep)
[ R1285LxxxA ]
[ R1285L00xB ]
Maximum Duty Cycle: 90%(Typ.)
Control
Short Protection with timer latch function (Typ. 50ms)
Short condition for either or both two outputs makes all output drivers off and latches. If the
maximum duty cycle continues for a certain time, these output drivers will be turned off. This
function prevents irregular current from overheating the R1285 .
CE with start up sequence function ( CH1→CH2 )
UVLO function.
Operating Frequency • • • • • 1400kHz
Small package • • • • • DFN2730-12
APPLICATION
z
z
Fixed voltage power supply for portable equipment
Fixed voltage power supply for OLED
V 1.4
1
R1285L
Non-promotion
BLOCK DIAGRAM
●R1285LxxxA
PVCC
LXP1
LXP2
Current
Limit
Osc
Maxduty
PWM
Control
PWM
Control
Timer
LXN
Maxduty
Current
Limit
Short
Protect
PGND
VOUTP
Discharge
Control
Discharge
Control
VOUTN
TST1
Vref3
Vref2
Vref1
Soft start1
TST2
Sequence
Control
Soft start2
Enable
Control
CE
UVLO
VCC
GND
●R1285L00xB
PVCC
LXP1
LXP2
Current
Limit
Osc
Maxduty
PWM
Control
PWM
Control
Timer
LXN
Maxduty
Current
Limit
Short
Protect
PGND
VOUTP
Discharge
Control
Discharge
Control
VOUTN
VFBN
VREF
Vref3
Vref2
Vref1
Soft start1
Sequence
Control
Soft start2
Enable
Control
CE
UVLO
VCC
GND
2
R1285L
Non-promotion
SELECTION GUIDE
The mask option for the ICs can be selected at the user's request. The selection can be made with designating the
part number as shown below.
Product Name
Package
DFN2730-12
Quantity per Reel
Pb Free
Halogen Free
5,000 pcs
○
○
R1285Lxx∗$-TR
xx :
Setting inverting output voltage (VOUTN
)
Stepwise setting with a step of 0.1V in the range of -2.0V(20) to -6.0(60)V is possible for fixed output
version.
"00" is for Output Voltage Adjustable version.
∗ :
Setting positive output voltage (VOUTP
)
（1）4.6V
（2）4.8V
（3）5.0V
$:
Designation of method of setting Inverting Voltage
（A）Fixed output version
（B）Adjustable version
The products scheduled to be discontinued : "Non-promotion"
These products will be discontinued in the future. We advise you to select other products.
3
R1285L
Non-promotion
PIN CONFIGURATION
● DFN 2730-12
Top View Bottom View
12 11 10
9
8
7
7
8
9
10 11 12
∗
1
2
3
4
5
6
6
5
4
3
2
1
PIN DESCRIPTIONS
●R1285LxxxA
PIN No.
NAME
PGND
VOUTP
PVCC
VCC
FUNCTION
1
2
Power GND pin
Output Voltage feedback pin for Step up DC/DC
Power input pin
3
4
Analog power source input pin
Analog GND pin
5
GND
CE
6
Chip enable pin
7
TST2
TST1
VOUTN
LXN
TEST pin
8
TEST pin
9
Output Voltage feedback pin for Inverting DC/DC
Switching pin for Inverting DC/DC
Shutdown switch output pin
Switching pin for Step up DC/DC
10
11
12
LXP1
LXP2
●R1285L00xB
PIN No.
NAME
PGND
VOUTP
PVCC
VCC
FUNCTION
Power GND pin
1
2
3
4
5
Output Voltage feedback pin for Step up DC/DC
Power input pin
Analog power source input pin
Analog GND pin
GND
CE
6
7
Chip enable pin
VREF
VFBN
VOUTN
LXN
Reference voltage output pin for Inverting DC/DC
Feedback pin for Inverting DC/DC
Output Voltage feedback pin for Inverting DC/DC
Switching pin for Inverting DC/DC
Shutdown switch output pin
8
9
10
11
12
LXP1
LXP2
Switching pin for Step up DC/DC
∗) Tab is GND level. (They are connected to the reverse side of this IC.)
The tab is better to be connected to the GND, but leaving it open is also acceptable.
4
R1285L
Non-promotion
ABSOLUTE MAXIMUM RATINGS
(GND / PGND=0V)
Item
VCC / PVCC pin Voltage
VOUTP pin Voltage
Symbol
VCC
Rating
-0.3 ~ 6.0
Unit
V
VOUTP
VCE
-0.3 ~ 6.0
V
CE pin Voltage
-0.3 ~ VCC+0.3
-0.3 ~ VCC+0.3
-0.3 ~ 6.0
V
LXP1 pin Voltage
VLXP
1
2
V
LXP2 pin Voltage
VLXP
V
LXN pin Voltage
VLXN
VOUTN
VTST
VFBN
VREF
PD
VCC-14 ~ VCC+0.3
VCC-14 ~ VCC+0.3
-0.3 ~ VCC+0.3
-0.7*1 ~ VCC+0.3
-0.7*1 ~ VCC+0.3
1000
V
VOUTN pin Voltage
V
TST1/TST2 pin Voltage [R1285LxxxA]
VFBN pin Voltage [R1285L00xB]
VREF pin Voltage [R1285L00xB]
Power Dissipation
V
V
V
mW
ºC
ºC
Operating Temperature Range
Storage Temperature Range
Ta
-40 ~ +85
Tstg
-55 ~ +125
∗1) In case the voltage range is from –0.7V to –0.3V, permissible current is 10mA or less.
ABSOLUTE MAXIMUM RATINGS
Electronic and mechanical stress momentarily exceeded absolute maximum ratings may cause the permanent
damages and may degrade the life time and safety for both device and system using the device in the field. The
functional operation at or over these absolute maximum ratings is not assured.
5
R1285L
Non-promotion
ELECTRICAL CHARACTERISTICS
(Ta=25ºC)
Symbol
VCC
ICC1
Item
Conditions
MIN.
2.3
TYP. MAX. Unit.
4.8
9.1
V
Operating Input Voltage
V
CC Consumption Current
(switching)
CC Consumption Current
4.0
mA
VCC=4.8V
VCC=4.8V
V
350
730
uA
ICC2
(at no switching)
0.1
3
uA
V
ISTB
Standby Current
VCC=4.8V
Falling
VUVLO
1
2
UVLO Detect Voltage
1.95
2.05
2.15
2.28
VUVLO1
+0.10
V
VUVLO
UVLO Released Voltage
Rising
1200 1400 1600 kHz
FOSC
TDLY
VCEL
VCEH
RCE
Oscillator Frequency
Delay Time for Protection
CE “L” Input Voltage
CE “H” Input Voltage
VCC=3.7V
VCC=3.7V
VCC=2.3V
VCC=4.8V
14
50
162
0.3
ms
V
1.5
V
300
600
900
kΩ
CE pin Pulldown Resistance VCC=3.7V
■Step-up DC/DC
x0.985
x1.015
V
VOUTP
VOUTP Voltage Tolerance
VCC=3.7V
VCC=3.7V , -40ºC Ta 85ºC
∆VOUTP
/∆T
∆VOUTP
/∆Vcc
∆VOUTP
/∆IOUT
V
V
V
OUTP Voltage
Temperature Coefficient
OUTP Voltage
Line Regulation
OUTP Voltage
ppm
/ºC
±
150
=
=
±4
±10
±10
mV
mV
mV
2.9V VCC 3.4, IOUT = 0mA
=
VCC=3.7V , 10mA IOUT 100mA
=
Load Regulation
VCC=2.9V ↔ 3.4V , TR=TF=50us
VOUTP Voltage
∆VOUTP_TR
Line Transient Response
IOUT = 100mA
78
85
4.5
300
91
10
%
ms
mΩ
uA
mΩ
uA
A
Maxduty1 CH1 Max. Duty Cycle
VCC=3.7V
1.6
TSS1
CH1 Soft-Start Time
LXP1 ON Resistance
VCC=3.7V
RLXP1
VCC=3.7V
5
IOFF LXP1 LXP1 Leakage Current
RLXP2 LXP2 ON Resistance
IOFF LXP2 LXP2 Leakage Current
VCC=4.8V , VLXP1=0V
VCC=3.7V
300
5
VCC=4.8V , VLXP2=5V
VCC=3.7V
0.61
2.8
1.0
5
1.68
10.3
ILIMLXP2
IVOUTP
LXP2 Current Limit
mA
VOUTP Discharge Current
VCC=3.7V , VOUTP=0.1V
6
R1285L
Non-promotion
■Inverting DC/DC [ R1285LxxxA]
x0.985
x1.015
VOUTN
VOUTN Voltage Tolerance
VCC=3.7V
∆VOUTN
/∆T
∆VOUTN
/∆Vcc
∆VOUTN
/∆IOUT
V
V
V
OUTN Voltage
Temperature Coefficient
OUTN Voltage
Line Regulation
OUTN Voltage
Load Regulation
ppm
/ºC
VCC=3.7V , -40ºC≦Ta≦85ºC
2.9V≦VCC≦3.4, IOUT = 0mA
VCC=3.7V , 10mA≦IOUT≦100mA
±
150
±6
mV
mV
mV
±15
±25
VCC=2.9V ↔ 3.4V , TR=TF=50us
IOUT = 100mA
∆VOUTN_TR
VOUTN Voltage
Line Transient Response
83
90
4.5
600
98
10
%
ms
mΩ
uA
A
Maxduty2 CH2 Max. Duty Cycle
VCC=3.7V
1.6
TSS2
CH2 Soft-Start Time
LXN ON Resistance
LXN Leakage Current
LXN Current Limit
VCC=3.7V
RLXN
VCC=3.7V
5
IOFF LXN
ILIMLXN
IVOUTN
VCC=4.8V , VLXN=-6V
VCC=3.7V
1.0
25
1.5
40
1.9
59
mA
VOUTN Discharge Current
VCC=3.7V , VOUTN=-0.3V
■Inverting DC/DC [ R1285L00xB]
-25
0
25
mV
μA
V
VFBN
VCC=3.7V
V
FBN voltage tolerance
FBN input current
-0.1
0.1
IFBN
VCC=4.8V , VFBN=0V or 4.8V
V
1.172
+VFBN +VFBN +VFBN
1.2
1.228
VREF
VCC=3.7V
VREF voltage tolerance
∆VREF
/∆T
∆VOUTN
V
REF voltage
VCC=3.7V
-40ºC≦Ta≦85ºC
ppm
/ºC
±150
temperature coefficient
OUTN Voltage
V
±6
mV
mV
mV
2.9V≦VCC≦3.4, IOUT = 0mA
/∆VCC
Line Regulation
∆VOUTN
/∆IOUT
VOUTN Voltage
±15
VCC=3.7V , 10mA≦IOUT≦100mA
Load Regulation
∆VOUTN_TR
VOUTN Voltage
VCC=2.9V ↔ 3.4V , TR=TF=50us
, IOUT = 100mA
±
25
Line Transient Response
83
90
98
10
%
ms
mΩ
uA
A
Maxduty2 CH2 Max. Duty Cycle
VCC=3.7V
1.6
4.5
TSS2
CH2 Soft-Start Time
LXN ON Resistance
LXN Leakage Current
LXN Current Limit
VCC=3.7V
600
RLXN
VCC=3.7V
5
IOFF LXN
ILIMLXN
IVOUTN
VCC=4.8V , VLXN=-6V
VCC=3.7V
1.0
25
1.5
40
1.9
59
mA
VOUTN Discharge Current
VCC=3.7V , VOUTN=-0.3V
* In terms of TST pin(TST1 , TST2), connect the GND level or remain it open.
RECOMMENDED OPERATING CONDITIONS (ELECTRICAL CHARACTERISTICS)
All of electronic equipment should be designed that the mounted semiconductor devices operate within the
recommended operating conditions. The semiconductor devices cannot operate normally over the recommended
operating conditions, even if when they are used over such conditions by momentary electronic noise or surge. And the
semiconductor devices may receive serious damage when they continue to operate over the recommended operating
conditions.
7
R1285L
Non-promotion
■Test Circuits
<VCC Consumption Current (switching)>
<VCC Consumption Current (no switching)>
PGND
PGND
VOUTP
LXP
2
LXP
2
1
VOUTP
LXP
L
XP1
PVCC
VCC
LXN
VOUTN
TST1
TST2
PVCC
VCC
LXN
VOUTN
TST1
TST2
GND
CE
GND
CE
A
A
<Standby Current>
<UVLO Detect Voltage>
PGND
VOUTP
LXP
2
1
LXP
PGND
VOUTP
LXP
2
PVCC
VCC
LXN
VOUTN
TST1
TST2
Oscilloscope
LXP1
PVCC
VCC
LXN
VOUTN
TST1
TST2
GND
CE
A
GND
CE
<UVLO Released Voltage>
<CH1 Oscillator Frequency/ Max.Duty>
Oscilloscope
Oscilloscope
PGND
PGND
VOUTP
L
XP2
LXP
2
VOUTP
LXP1
L
XP1
PVCC
VCC
LXN
VOUTN
TST1
TST2
PVCC
VCC
LXN
VOUTN
TST1
TST2
GND
CE
GND
CE
*In case of the R1285L00xB, the pin name is changed from TST1 to V
FBN and TST2 to VREF
.
8
R1285L
Non-promotion
<Delay Time for Protection>
PGND
<CH2 Oscillator Frequency/ Max.Duty>
PGND
VOUTP
LXP
2
1
Oscilloscope
Oscilloscope
LXP
L
XP2
PVCC
VCC
LXN
VOUTN
TST1
TST2
LXP
1
VOUTP
PVCC
VCC
LXN
GND
CE
VOUTN
TST1
TST2
GND
CE
Function
Generator
■Step-up DC/DC
<VOUTP Voltage Line Regulation >
D1
< VOUTP Voltage Tolerance>
LXP2
1
PGND
V
Oscilloscope
LXP
LXP
2
1
PGND
VOUTP
PVCC
VCC
L1
L2
LXN
VOUTN
LXP
VOUTP
PVCC
VCC
LXN
VOUTN
D2
TST1
TST2
GND
CE
TST1
TST2
GND
CE
C2
C1
C3
A
<VOUTP Voltage Line Transient Response>
<VOUTP Voltage Load Regulation >
D1
Buffer Circuit
D1
V
LXP
2
VCC
PGND
LXP
2
1
PGND
V
AC IN
LXP1
LXP
VOUTP
PVCC
VCC
L1
L2
VOUTP
PVCC
VCC
L1
L2
GND
OUT
LXN
VOUTN
LXN
VOUTN
D2
D2
TST1
TST2
TST1
TST2
GND
CE
GND
CE
Function
Generator
C2
C2
C3
A
C1
C1
C3
V
V
and TST2 to VREF
.
*In case of the R1285L00xB, the pin name is changed from TST1 to VFBN
9
R1285L
Non-promotion
<Lxp1 ON Resistance>
PGND
<CH1 Soft-Start Time>
L
XP2
LXP
LXN
Oscilloscope
1
VOUTP
PVCC
LXP
2
1
PGND
LXP
VOUTP
PVCC
VCC
VOUTN
TST1
TST2
VCC
LXN
VOUTN
GND
CE
V
TST1
TST2
GND
CE
Function
Generator
< Lxp2 ON Resistance >
< Lxp1 Leakage Current >
LXP
2
1
LXP
2
1
PGND
VOUTP
PVCC
PGND
VOUTP
LXP
LXP
LXN
VOUTN
TST1
TST2
LXN
PVCC
VCC
VOUTN
VCC
GND
CE
A
TST1
TST2
GND
CE
V
< Lxp2 Current Limit>
< Lxp2 Leakage Current >
Oscilloscope
PGND
VOUTP
LXP
2
1
PGND
VOUTP
PVCC
LXP
LXP
LXN
VOUTN
TST1
TST2
2
LXP
1
PVCC
VCC
LXN
VOUTN
TST1
TST2
VCC
GND
CE
GND
CE
A
<VOUTP Discharge Current >
PGND
VOUTP
LXP
2
1
LXP
PVCC
VCC
LXN
VOUTN
TST1
TST2
GND
CE
A
and TST2 to VREF
.
*In case of the R1285L00xB, the pin name is changed from TST1 to VFBN
10
R1285L
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■Inverting DC/DC
<VOUTN Voltage Line Regulation>
D1
<VOUTN Voltage Tolerance>
LXP
2
1
PGND
LXP2
PGND
LXP
VOUTP
PVCC
VCC
Oscilloscope
LXP
1
VOUTP
PVCC
VCC
LXN
VOUTN
L1
LXN
VOUTN
L2
TST1
TST2
GND
CE
TST1
TST2
GND
CE
V
C1
C3
C2
A
<VOUTN Voltage Load Regulation >
D1
<VOUTN Voltage Line Transient Response>
D1
Buffer Circuit
VCC
LXP2
PGND
LXP
2
1
PGND
AC IN
L1
L2
LXP
1
LXP
L1
L2
VOUTP
PVCC
VCC
VOUTP
PVCC
VCC
GND
OUT
LXN
LXN
D2
D2
VOUTN
VOUTN
TST1
TST2
TST1
TST2
GND
CE
GND
CE
Function
Generator
V
V
C3
C1
C1
C2
C2
A
C3
V
V
<LXN ON Resistance>
PGND
<CH2 Soft-Start Time >
LXP
2
1
LXP
2
1
PGND
Oscilloscope
LXP
LXP
VOUTP
PVCC
VCC
VOUTP
PVCC
VCC
LXN
LXN
VOUTN
VOUTN
TST1
TST2
TST1
TST2
GND
CE
GND
CE
V
Function
Generator
and TST2 to VREF
.
*In case of the R1285L00xB, the pin name is changed from TST1 to VFBN
11
R1285L
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< LXN Leakage Current >
< LXN Current Limit>
PGND
VOUTP
LXP
2
1
PGND
VOUTP
LXP
2
1
Oscilloscope
LXP
LXP
PVCC
VCC
LXN
VOUTN
TST1
TST2
PVCC
VCC
LXN
VOUTN
GND
CE
GND
CE
TST1
TST2
A
<VOUTN Discharge Current >
PGND
VOUTP
LXP
2
L
XP1
PVCC
VCC
LXN
VOUTN
TST1
TST2
GND
CE
A
*In case of the R1285L00xB, the pin name is changed from TST1 to VFBN and TST2 to VREF
.
12
R1285L
Non-promotion
TYPICAL APPLICATION AND TECHNICAL NOTES
●R1285LxxxA
VOUTP
C3
10uF
D1
L2
L1
L2
VLS252010T-4R7M
PGND
VOUTP
PVCC
VCC
LXP2
(TDK)
L1
VLS252010T-4R7M
(TDK)
LXP1
LXN
D1
D2
C1
C2
RSX051VA-30 (Rohm)
D2
VOUTN
VOUTN
C1
4.7uF
RSX051VA-30 (Rohm)
4.7uF 1608size
C2
10uF
GND
CE
TST1
TST2
CT21X5R106K10A095
( Kyocera)
EN control
C3
CT21X5R106K10A095
( Kyocera)
●R1285L00xB
VOUTP
C3
10uF
D1
L2
PGND
VOUTP
PVCC
VCC
LXP2
L1
LXP1
LXN
D2
R2 R3
R1 C4
C5
VOUTN
VOUTN
VFBN
VREF
C1
4.7uF
C2
10uF
GND
CE
EN control
●Set a ceramic 4.7μF or more capacitor between Vcc and GND as C1.
●Set a ceramic10μF or more capacitor between VOUTP and GND, and between VOUTN and GND for each as
C2 and C3.
●Start up Sequence
When CE level turns from ‘L’ to ‘H’ level, the softstart of CH1 starts the operation. After detecting output voltage of
CH1(VOUTP)as the nominal level, the soft start of CH2 starts the operation.
CE
CH1 (VOUTP
)
Soft start CH1
Soft Start CH2
0V
CH2 (VOUTN
)
13
R1285L
Non-promotion
●Auto Discharge Function
When CE level turns from ‘H’ to ‘L’ level, the R1285 goes into standby mode and switching of the outputs of
LXP2 and LXN will stop. Then dischage switch between VOUTN and PVCC and switch between VOUTP and GND
turn on and discharge the negative output voltage and positive output voltage. When the negative output
voltage is discharged to 0V, the switch between VOUTN and PVCC turns off and the negative output will be
Hi-Z. Positive output voltage is discharged to 0V In standby mode.
If Vcc voltage became lower than UVLO detect voltage , discharge switches also turn on and discharge
output voltage(VOUTN and VOUTP) .
In case of timer latch protection,discharge switches will keep off .
CE
VOUTP
0V
Hi-Z (VOUTN
0V (VOUTP
)
VOUTN
Discharge
)
●Short protection circuit timer
In case that the voltage of VOUTP drops, the error amplifier of CH1 outputs "H". In case that the voltage of
VOUTN rises, the error amplifier of CH2 outputs "L". The built-in short protection circuit makes the internal
timer operate with detecting the output of the error amplifier of CH1 as "H", or the output of the error
amplifier of CH2 as "L". After the setting time will pass, the switching of LXP2 and LXN will stop and shutdown
switch will turn off and both of discharge switches will keep off .
To release the latch operation, make the Vcc set equal or less than UVLO level and restart or set the CE pin
as "L" and make it "H" again.
During the softstart operation of CH1and CH2, the timer operates independently from the outputs of the
error amplifiers. Therefore, even if the softstart cannot finish correctly because of the short circuit, the
protection timer function will be able to work correctly.
Amp output for Boost
Amp output for Inverting
Normal state
Short state
Latch state
Shutdown
Timer function (Typ. 50ms)
During a timer function, current is
After shutdown
restricted by current limit protection drivers and shutdown
or maxduty function until shutdown . switch turn off
14
R1285L
Non-promotion
●Inverting DC/DC converter output voltage setting [ R1285L00xB ]
The output voltage VOUTN of the inverting DC/DC converter is controlled with maintaining the VFBN as 0V.
VOUTN can be set with adjusting the values of R1 and R2 as in the next formula.
VOUTN = VFBN - (VREF-VFBN) x R2 / R1
DC/DC converter’s phase may lose 180 degree by external components of L and C and load current. Because of
this, the phase margin of the system will be less and the stability will be worse. Therefore, the phase must be
gained.
A pole will be formed by external components, L and C.
Fpole ~ 1 / {2 x π x √(L2xC2)}
Zero will be formed with R2 and C4.
Fzero ~ 1 / (2 x π x R2 x C4)
Set the cut-off frequency of the Zero close to the cut-off frequency of the pole by L and C.
If the noise of the system is large, the output noise affects the feedback and the operation may be unstable. In
that case, another resistor R3 will be set. The appropriate value range is from 1kΩ to 5kΩ.
●Set a ceramic 1μF to 2.2μF capacitor between VREF and GND as C5. [ R1285L00xB ]
Operation of Step-up DC/DC Converter and Output Current
<Basic Circuit>
IL2
Inductor
Diode
Lx Tr
IOUT
VOUT
VIN
IL1
CL
<Current through L>
IL
Continuous Mode
Discontinuous Mode
ILxmax
ILxmax
IL
ILxmin
ILxmin
Tf
t
t
Ton
T=1/fosc
Toff
Ton
T=1/fosc
Toff
15
R1285L
Non-promotion
There are two operation modes for the PWM control step-up switching regulator, that is the continuous mode
and the discontinuous mode.
When the LX Tr. is on, the voltage for the inductor L will be VIN. The inductor current (IL1) will be;
IL1 = VIN x Ton / L ...............................................................................................................Formula1
When the Lx transistor turns off, power will supply continuously. The inductor current at off (IL2) will be;
IL2 = (VOUT-VIN) x Tf / L .....................................................................................................Formula2
In terms of the PWM control, when the Tf=Toff, the inductor current will be continuous, the operation of the
switching regulator will be continuous mode.
In the continuous mode, the current variation of IL1 and IL2 are same, therefore
VIN x Ton / L = (VOUT-VIN) x Toff / L
....................................................................................Formula3
In the continuous mode, the duty cycle will be
DUTY = Ton / (Ton+Toff) = (VOUT-VIN) / VOUT ........................................................................Formula4
If the input power equals to output power,
IOUT = VIN2 x Ton / (2 x L x VOUT
)
.......................................................................................Formula5
When IOUT becomes more then Formula5, it will be continuous mode.
In this moment, the peak current, ILxmax flowing through the inductor is described as follows:
ILxmax = IOUT x VOUT / VIN + VIN x Ton /(2 x L)
ILxmax = IOUT x VOUT / VIN + VIN x Tx (VOUT-VIN) /(2 x L x VOUT
..................................................................Formula6
.......................................Formula7
)
Therefore, peak current is more than IOUT. Considering the value of ILxmax, the condition of input and output,
and external components should be selected.
The explanation above is based on the ideal calculation, and the loss caused by Lx switch and external
components is not included.
The actual maximum output current is between 50% and 80% of the calculation.
Especially, when the IL is large, or VIN is low, the loss of VIN is generated with on resistance of the switch.
As for VOUT, VF(as much as 0.3V)of the diode should be considered.
Operation of Inverting DC/DC Converter and Output Current
<Basic Circuit>
Lx Tr
Diode
IOUT
VOUT
VIN
IL1
IL2
Inductor
CL
16
R1285L
Non-promotion
<Current through L>
Discontinuous Mode
ILxmax
Continuous Mode
ILxmax
IL
IL
ILxmin
ILxmin
Tf
t
t
Ton
T=1/fosc
Toff
Ton
T=1/fosc
Toff
There are also two operation modes for the PWM control inverting switching regulator, that is the continuous
mode and the discontinuous mode.
When the LX Tr. is on, the voltage for the inductor L will be VIN. The inductor current (IL1) will be;
IL1 = VIN x Ton / L...................................................................................................................Formula8
Inverting circuit saves energy during on time of Lx Tr, and supplies the energy to output during off time,
output voltage opposed to input voltage is obtained. The inductor current at off (IL2) will be;
IL2 = VOUT x Tf / L .................................................................................................................Formula9
(The above formula and after, the absolute value of the negative output voltage is assumed to be
VOUT
.
: Output voltage= -10V , VOUT=10 )
In terms of the PWM control, when the Tf=Toff, the inductor current will be continuous, the operation of the
switching regulator will be continuous mode.
In the continuous mode, the current variation of IL1 and IL2 are same, therefore
VIN x Ton / L = VOUT x Toff / L...................................................................................................Formula10
In the continuous mode, the duty cycle will be:
DUTY = Ton / (Ton+Toff) = VOUT / (VOUT + VIN )........................................................................Formula11
If the input power equals to output power,
IOUT = VIN2 x Ton / (2 x L x VOUT) .............................................................................................Formula12
When IOUT becomes more then Formula12 , it will be continuous mode.
In this moment ,the peak current, ILxmax flowing through the inductor is described as follows:
ILxmax = IOUT x VOUT / VIN + VIN x Ton / (2 x L)...........................................................................Formula13
ILxmax = IOUT x VOUT / VIN + VIN x VOUT x T / { 2 x L x (VOUT + VIN ) }.........................................Formula14
Therefore, peak current is more than IOUT. Considering the value of ILxmax, the condition of input and output,
and external components should be selected.
The explanation above is based on the ideal calculation, and the loss caused by Lx switch and external
components is not included.
The actual maximum output current is between 50% and 80% of the calculation.
Especially, when the IL is large, or VIN is low, the loss of VIN is generated with on resistance of the switch. As
for VOUT, VF(as much as 0.3V)of the diode should be considered.
17
R1285L
Non-promotion
■
R1285LxxxX Typical Characteristics
1) Output voltage vs. Output Current
R1285Lxx1A/001B(VOUTP= 4.6V)
R1285L49xA(VOUTN= -4.9V)
Ta=25°C
Ta=25°C
4.7
4.68
4.66
4.64
4.62
4.6
-4.8
-4.82
-4.84
-4.86
-4.88
-4.9
-4.92
-4.94
-4.96
-4.98
-5
4.58
4.56
Vin= 4.5
Vin= 4.5
VIN=4.5V
VIN=4.5V
4.54
4.52
4.5
Vin= 3.7
Vin= 3.7
VIN=3.7V
VIN=3.7V
Vin= 2.9
Vin= 2.9
VIN=2.9V
VIN=2.9V
0
20
40
60
80
100 120 140 160 180 200
0
20
40
60
80
100 120 140 160 180 200
IOUT P [mA ]
IOUT N [mA]
R1285L54xA(VOUTN= -5.4V)
R1285L00xB(VOUTN= -4.9V)
Ta=25°C
Ta=25°C
-5.3
-5.32
-5.34
-5.36
-5.38
-5.4
-4.8
-4.82
-4.84
-4.86
-4.88
-4.9
-5.42
-5.44
-5.46
-5.48
-5.5
-4.92
-4.94
-4.96
-4.98
-5
VV in==4.54V.5
V
IN=4.5V
IN
Vin= 4.5
V
IN=3.7V
V
IN=3.7V
Vin= 3.7
Vin= 3.7
V
IN=2.9V
V
IN=2.9V
Vin= 2.9
Vin= 2.9
0
20
40
60
80
100 120 140 160 180 200
0
20
40
60
80
100 120 140 160 180 200
IOUT N [mA]
IOUT N [mA]
R1285L00xB(VOUTN= -5.4V)
INVERTING
Ta=25°C
Topt=25
℃
-5.26
-5.28
-5.3
-5.32
-5.34
-5.36
-5.38
-5.4
VVIiNn==4.54V.5
IN=3.7V
-5.42
-5.44
-5.46
V
Vin= 3.7
VIN=2.9V
Vin= 2.9
0
20
40
60
80
100 120 140 160 180 200
IOUT N [mA]
2) Efficiency vs. Output Current
R1285Lxx1A/001B(VOUTP= 4.6V)
R1285L49xA(VOUTN= -4.9V)
Ta=25°C
Ta=25°C
100
90
80
70
60
50
40
30
20
100
90
80
70
60
50
40
30
20
VIN=4.5V
VIN=4.5V
Vin= 4.5
Vin= 4.5
V
IN=3.7V
VIN=3.7V
Vin= 3.7
Vin= 3.7
V
IN=2.9V
VIN=2.9V
Vin= 2.9
Vin= 2.9
0
20
40
60
80
100 120 140 160 180 200
0
20
40
60
80
100 120 140 160 180 200
IOUT P [mA ]
IOUT N [mA]
18
R1285L
Non-promotion
Ta=25°C
OUTP=0mA
Ta=25°C
R1285L54xA(VOUTN= -5.4V)
R1285L00xB(VOUTN= -4.9V)
I
IOUTP=0mA
100
90
80
70
60
50
40
30
20
100
90
80
70
60
50
40
30
20
Vin= 4.5
VIN=4.5V
Vin= 4.5
IN=4.5V
V
Vin= 3.7
VIN=3.7V
Vin= 3.7
VIN=3.7V
Vin= 2.9
VIN=2.9V
Vin= 2.9
VIN=2.9V
0
20
40
60
80
100 120
140
160
180
200
0
20
40
60
80
100
120
140
160
180
200
IOUT N [mA]
IOUT N [mA]
Ta=25°C
R1285L00xB(VOUTN= -5.4V)
R1285L00xB(VoutN= -4.9V)
Topt=25
℃
IOUTP=0mA
100
90
80
70
60
50
40
30
20
Vin= 4.5
IN=4.5V
V
Vin= 3.7
VIN=3.7V
Vin= 2.9
VIN=2.9V
0
20
40
60
80
100
120
140
160
180
200
IOUT N [mA]
3) Output Current vs. Output Voltage (Load Regulation)
R1285Lxx1A/001B(VOUTP= 4.6V)
R1285L49xA(VOUTN= -4.9V)
Ta=25°C
Toap=t2=52°5C
℃
50
40
30
20
10
0
50
40
30
20
10
0
-10
-20
-30
-40
-50
-10
-20
Vin= 4.5
VIN=4.5V
Vin= 4.5
VIN=4.5V
-30
-40
-50
Vin= 3.7
VIN=3.7V
VVin=3=.73V.7
IN
Vin= 2.9
VIN=2.9V
VIN=2.9V
Vin= 2.9
0
20
40
60
80
100
120
0
20
40
60
80
100
120
IOUT N [mA]
IOUT P [mA]
R1285L54xA(VOUTN= -5.4V)
R1285L00xB(VOUTN= -4.9V)
Ta=25°C
Ta=25°C
50
40
50
40
30
30
20
20
10
10
0
0
-10
-20
-30
-40
-50
-10
-20
-30
-40
-50
VVIiNn==4.45V.5
Vin= 4.5
VIN=4.5V
V
=3.7V
VIiNn= 3.7
Vin= 3.7
VIN=3.7V
VVIiNn==2.29V.9
Vin= 2.9
VIN=2.9V
0
20
40
60
80
100
120
0
20
40
60
80
100
120
IOUT N [mA]
IOUT N [mA]
19
R1285L
Non-promotion
R1285L00xB(VOUTN= -5.4V)
R1285L00xB(VoutN= -4.9V)
Ta=25
℃
50
40
30
20
10
0
-10
-20
-30
-40
VIN=4.5V
VIN=3.7V
VIN=2.9V
-50
0
20
40
60
80
100
120
IOUT N [mA]
4)ꢀTurn-on/Turn-off Speed by CE signal
R1285L491A
R1285L001B(VOUTN= -4.9V)
Topt=25
℃
CE
CE
V
OUTP
N
VO TP
U
U
VIN = 3.7V, IOUT = 0mA, ta = 25°C
V
OUT
VO TN
VIN = 3.7V, IOUT = 0mA, ta= 25°C
IRUSH
IRUSH
6.0
4.0
6.0
4.0
2.0
2.0
0.0
300
0.0
-2.0
-4.0
-6.0
-8.0
200
100
0
-2.0
-4.0
-6.0
-8.0
100
50
0
-50
-100
-2
0
2
4
6
8
10 12 14 16 18
-2
0
2
4
6
8
10
12
14
16 18
time [ms]
time [ms]
5) Load Transient Response
R1285Lxx1A(VOUTP= 4.6V)
R1285L49xA(VOUTN= -4.9V)
Topt=25
℃
VIN = 3.7V, ta= 25°C, tr / tf = 10us
VIN = 3.7V, ta= 25°C, tr / tf = 10us
4.700
4.675
4.650
4.625
4.600
4.575
4.550
4.525
4.500
-4.65
-4.70
-4.75
-4.80
-4.85
-4.90
-4.95
-5.00
Output Voltage
Output Voltage
100
50
100
50
0
-50
-100
-150
0
Load Current
Load Current
-50
-100
-200 -100
0
100
300
500
600
700
800
-100
0
100
200
400
600
700
800
900
200 time [us]400
300 time [us]500
6) Line Transient Response
R1285Lxx1A(VOUTP= 4.6V)
R1285L49xA(VOUTN= -4.9V)
Load Current = 100mA, ta = 25°C, tr / tf = 50us
Load Current = 100mA, ta = 25°C, tr / tf = 50us
-4.850
4.700
4.675
4.650
4.625
4.600
4.575
-4.875
-4.900
-4.925
-4.950
Output Voltage
Input Voltage
Output Voltage
Input Voltage
3.4
2.9
2.4
3.4
2.9
2.4
-100
0
100
200
300
400
500
600
700
800
900
-100
0
100
200
300
400
500
600
700
800
900
time [us]
time [us]
20
R1285L
Non-promotion
7) UVLO Voltage VS. Temperature
R1285Lxxxx
8) VOUTP Voltage VS. Temperature
R1285Lxx1A
2.25
2.2
4.7
4.65
4.6
2.15
UVLO Release
2.1
2.05
4.55
4.5
UVLO
2
1.95
1.9
4.45
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
Ta [°C]
Ta [°C]
9) VOUTN Voltage VS. Temperature
R1285L20xA
R1285L48xA
-1.95
-1.97
-1.99
-2.01
-2.03
-2.05
-4.65
-4.7
-4.75
-4.8
-4.85
-4.9
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
Ta [°C]
Ta [°C]
) UVLO 検出/復帰電圧対周囲温度特性例
R1285L60xA
R1285Lxxxx
-5.85
-5.9
-5.95
-6
-6.05
-6.1
-6.15
-40
-20
0
20
40
60
80
Ta [°C]
21
R1285L
Non-promotion
10) VFBN Voltage VS. Temperature
R1285L00xB
11) VREF Voltage VS. Temperature
R1285L00xB
0.03
0.02
0.01
0
1.22
1.21
1.2
1.19
1.18
1.17
1.16
-0.01
-0.02
-0.03
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
Ta [°C]
Ta [°C]
12) LXP1 ON Resistance VS. Temperature
R1285Lxxxx
13) LXP2 ON Resistance VS. Temperature
R1285Lxxxx
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
Ta [°C]
Ta [°C]
14) LXN ON Resistance VS. Temperature
R1285Lxxxx
15) LXP2 Current Limit VS. Temperature
R1285Lxxxx
0.8
0.6
0.4
0.2
0
1.6
1.4
1.2
1
0.8
0.6
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
Ta [°C]
Ta [°C]
22
R1285L
Non-promotion
16) LXN Current Limit VS. Temperature
17) Oscillator Frequency VS. Temperature
R1285Lxxxx
R1285Lxxxx
2
1500
1.8
1.6
1.4
1.2
1
1450
1400
1350
1300
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
Ta [°C]
Ta [°C]
18) Maxduty1 VS. Temperature
R1285Lxxxx
19) Maxduty2 VS. Temperature
R1285Lxxxx
88
87
86
85
84
83
82
94
93
92
91
90
89
88
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
Ta [°C]
Ta [°C]
20) CH1 Soft-Start Time VS. Temperature
R1285Lxxxx
21) CH2 Soft-Start Time VS. Temperature
R1285Lxxxx
8
7
6
5
4
3
2
1
8
7
6
5
4
3
2
1
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
Ta [°C]
Ta [°C]
23
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
information thereon.
2.The materials in this document may not be copied or otherwise reproduced in whole or in part
without prior written consent of Ricoh.
3.Please be sure to take any necessary formalities under relevant laws or regulations before
exporting or otherwise taking out of your country the products or the technical information
described herein.
4.The technical information described in this document shows typical characteristics of and
example application circuits for the products. The release of such information is not to be
construed as a warranty of or a grant of license under Ricoh's or any third party's intellectual
property rights or any other rights.
5.The products listed in this document are intended and designed for use as general electronic
components in standard applications (office equipment, telecommunication equipment,
measuring instruments, consumer electronic products, amusement equipment etc.). Those
customers intending to use a product in an application requiring extreme quality and reliability,
for example, in a highly specific application where the failure or misoperation of the product
could result in human injury or death (aircraft, spacevehicle, nuclear reactor control system,
traffic control system, automotive and transportation equipment, combustion equipment, safety
devices, life support system etc.) should first contact us.
6.We are making our continuous effort to improve the quality and reliability of our products, but
semiconductor products are likely to fail with certain probability. In order to prevent any injury to
persons or damages to property resulting from such failure, customers should be careful enough
to incorporate safety measures in their design, such as redundancy feature, firecontainment
feature and fail-safe feature. We do not assume any liability or responsibility for any loss or
damage arising from misuse or inappropriate use of the products.
7.Anti-radiation design is not implemented in the products described in this document.
8.Please contact Ricoh sales representatives should you have any questions or comments
concerning the products or the technical information.
For the conservation of the global environment, Ricoh is advancing the decrease of the negative environmental impact material.
After Apr. 1, 2006, we will ship out the lead free products only. Thus, all products that will be shipped from now on comply with RoHS Directive.
Basically after Apr. 1, 2012, we will ship out the Power Management ICs of the Halogen Free products only. (Ricoh Halogen Free products are
also Antimony Free.)
Halogen Free
RICOH COMPANY, LTD.
Electronic Devices Company
http://www.ricoh.com/LSI/
RICOH COMPANY, LTD.
Electronic Devices Company
● Higashi-Shinagawa Office (International Sales)
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Electronic Devices Company
● Taipei office
Room109, 10F-1, No.51, Hengyang Rd., Taipei City, Taiwan (R.O.C.)
Phone: +886-2-2313-1621/1622 Fax: +886-2-2313-1623
相关型号：
R1285L201A-TR-F
Switching Regulator, 1400kHz Switching Freq-Max, PDSO12, 2.7 X 3 MM, ROHS COMPLIANT, DFN-12
RICOH
R1285L202A-TR
Switching Regulator, 1.9A, 1600kHz Switching Freq-Max, PDSO12, 2.70 X 3 MM, HALOGEN AND LEAD FREE, DFN-12
RICOH
R1285L202A-TR-F
Switching Regulator, 1400kHz Switching Freq-Max, PDSO12, 2.7 X 3 MM, ROHS COMPLIANT, DFN-12
RICOH
R1285L203A-TR-F
Switching Regulator, 1400kHz Switching Freq-Max, PDSO12, 2.7 X 3 MM, ROHS COMPLIANT, DFN-12
RICOH
R1285L211A-TR
Switching Regulator, 1.9A, 1600kHz Switching Freq-Max, PDSO12, 2.70 X 3 MM, HALOGEN AND LEAD FREE, DFN-12
RICOH
R1285L211A-TR-F
Switching Regulator, 1400kHz Switching Freq-Max, PDSO12, 2.7 X 3 MM, ROHS COMPLIANT, DFN-12
RICOH
R1285L212A-TR
Switching Regulator, 1.9A, 1600kHz Switching Freq-Max, PDSO12, 2.70 X 3 MM, HALOGEN AND LEAD FREE, DFN-12
RICOH
R1285L212A-TR-F
Switching Regulator, 1400kHz Switching Freq-Max, PDSO12, 2.7 X 3 MM, ROHS COMPLIANT, DFN-12
RICOH
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