RT9261/A
VFM Step-Up DC/DC Converter
General Description
Features
The RT9261 Series are VFM Step-up DC/DC ICs with ultra
low supply current by CMOS process and suitable for
use with battery-powered instruments.
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The RT9261 IC consists of an oscillator, a VFM control
circuit, a driver transistor (LX switch), a reference voltage
unit, an error amplifier, resistors for voltage detection, and
a LX switch protection circuit. A low ripple and high
efficiency step-up DC/DC converter can be constructed of
this RT9261 IC with only three external components.
z
z
z
z
z
z
z
z
The RT9261A IC provides with a drive pin (EXT) for an
external transistor, so that a power transistor can be
externally applied. Therefore, the RT9261A IC is
recommended for applications where large currents are
required. EN pin enables circuit to set the standby supply
current at a maximum of 0.5μA.
Ordering Information
RT9261/APackage Type
B : SOT-23-5
X : SOT-89
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commercial Standard)
Output Voltage
15 : 1.5V
16 : 1.6V
:
49 : 4.9V
50 : 5.0V
Minimal Number of External Components ( Only
an Inductor, a Diode, and a Capacitor)
μA at Switch Off)
Ultra Low Input Current ( 5μ
±2% High Output Voltage Accuracy
Low Ripple and Low Noise
Low Start-up Voltage, 0.85V at 1mA
75% Efficiency with Low Cost Inductor
+50 ppm/ °C Low Temperature-Drift
SOT-89 and SOT-23-5 Small Packages
RoHS Compliant and 100% Lead (Pb)-Free
Applications
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z
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Power source for battery-powered equipment
Power source for cameras, camcorders, VCRs, PDAs,
pagers, electronic data banks, and hand-held
communication equipment
Power source for applications, which require higher
voltage than that of batteries used in the appliances
Pin Configurations
(TOP VIEW)
1
2
3
RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
`
Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area, otherwise visit our website for detail.
DS9261/A-15 April 2010
3
GND VOUT EXT
(TAB)
RT9261
RT9261A
SOT-89
Note :
`
2
GND VOUT LX
(TAB)
Use external switch
Use internal switch
Richtek Pb-free and Green products are :
1
LX
GND
EXT
GND
5
4
5
4
2
3
2
3
EN VOUT NC
EN VOUT NC
RT9261
RT9261A
SOT-23-5
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1
RT9261/A
Typical Application Circuit
L1
D1
L1
1N5819
27µH
VIN
1N5819
Cb
0.01µF
VOUT
RT9261AxX
EXT
VOUT
GND
VIN
COUT
22µF
ZTX
650
Tr Rb
300
Figure 1
L1
RT9261xB
LX
VOUT
VOUT
VIN
Cb
0.01µF
COUT
RT9261AxB
VOUT
COUT
22µF
EXT
22µF
ZTX
650
GND
Tr Rb
300
Figure 3
EN
VOUT
+
NC
EN
1N5819
NC
+
VIN
VOUT
D1
27µH
1N5819
100µH
COUT
22µF
Figure 2
D1
L1
+
100µH
+
RT9261xX
LX
VOUT
GND
D1
GND
Figure 4
D1
1N5819
L1
27µH
VIN
NC
Chip
Enable
EN
+
RT9261xB
LX
VOUT
VOUT
COUT
22µF
GND
Figure 5
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DS9261/A-15 April 2010
RT9261/A
Functional Pin Description
Pin No.
RT9261-□ □□X RT9261A- □□□X RT9261-□ □□B RT9261A-□□ □B
Pin Name
Pin Function
1
1
4
4
GND
Ground.
2
2
2
2
VOUT
Output Voltage.
3
--
5
--
LX
Pin for Switching.
--
3
--
5
EXT
Drive External Device.
--
--
1
1
EN
Chip Enable (Active High).
--
--
3
3
NC
No Internal Connected.
Function Block Diagram
VLX Limiter
LX
VREF
LXSW
Buffer
VOUT
GND
-
VFM Control
EXT
+
Error
Amplifier
OSC 100kHz
Chip Enable
EN
Notes:
(1) LX Pin......
only for 9261-
(2) EXT Pin....
only for 9261A-
(3) EN Pin......
only for 9261-
DS9261/A-15 April 2010
xX and 9261xX and 9261AxB and 9261A-
xB
xB
xB
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3
RT9261/A
Absolute Maximum Ratings
Output Voltage -------------------------------------------------------------------------------------------------------LX Pin Voltage (1) -----------------------------------------------------------------------------------(2)
z EXT Pin Voltage
--------------------------------------------------------------------------------------------------(3)
z EN Pin Voltage
---------------------------------------------------------------------------------------------------(1)
z LX Pin Output Current
-------------------------------------------------------------------------------------------(2)
z EXT Pin Current
--------------------------------------------------------------------------------------------------z Power Dissipation, PD @ TA = 25°C
SOT-89 -----------------------------------------------------------------------------------------------------------------SOT-23-5 --------------------------------------------------------------------------------------------------------------z Package Thermal Resistance
SOT-89, θJC -----------------------------------------------------------------------------------------------------------SOT-89, θJA -----------------------------------------------------------------------------------------------------------SOT-23-5, θJA ---------------------------------------------------------------------------------------------------------z Operating Temperature Range ------------------------------------------------------------------------------------z Storage Temperature Range --------------------------------------------------------------------------------------z Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------Notes:
(1) Applicable to RT9261xX and RT9261xB
(2) Applicable to RT9261AxX and RT9261AxB
(3) Applicable to RT9261xB and RT9261AxB
z
z
Electrical Characteristics
Parameter
8V
8V
−0.3 to VOUT +0.3V
−0.3 to VOUT +0.3V
250mA
±50mA
0.5W
0.25W
100°C/W
300°C/W
250°C/W
−20 to +85°C
165°C
260°C
(Refer to Figure 1)
Symbol
Test Conditions
Min
Typ
Max Units
Output Voltage Accuracy
ΔVOUT
−2
--
+2
%
Input Voltage
VIN
--
--
7
V
Start-up Voltage
VST
IOUT = 1mA, VIN: 0 → 2V
--
0.85
1.0
V
Hold-on Voltage
VHO
IOUT = 1mA, VIN: 2 → 0V
0.7
--
--
V
--
15
18
--
18
24
μA
--
5
8
60
--
--
80
--
--
--
--
0.5
μA
80
120
160
kHz
V OUT = 2.5V to 5V
65
75
85
%
V OUT = 1.5V to 2.4V
60
70
80
%
--
75
--
%
0.65
0.8
1.0
V
V OUT ≤ 3.5V
Input Current 1
V IN at no load
Input Current 2
V OU T in switch off condition
LX Switching Current
ISWITCHING
V LX = 0.4V
LX Leakage Current
ILEAKAGE
V LX = 6V
Maximum Oscillator
FMAX
Oscillator Duty Cycle
DOSC
On ( V LX ” L ” ) side
Efficiency
VLX Voltage Limit
L X switch on
(1)
3.5V < VO UT ≤ 5V
V OUT ≤ 3.5V
(2)
(1)
3.5V < VO UT ≤ 5V
(2)
μA
mA
Notes:
(1)Unless otherwise provided, VIN = 1.8V, VSS = 0V, IOUT = 10mA, TOPT = 25°C, and External Circuit of Typical Application
(2)Unless otherwise provided, VIN = 3V, VSS = 0V, IOUT = 10mA, TOPT = 25°C, and External Circuit of Typical Application
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DS9261/A-15 April 2010
RT9261/A
Electrical Characteristics
Parameter
(Refer to Figure 2)
Symbol
Output Voltage Accuracy
Input Voltage
ΔVOUT
VIN
Start-up Voltage
VST
Test Conditions
IOUT = 1mA, V IN : 0 → 2V
VOUT ≤ 3.5V
3.5V < V OU T ≤ 5V
(1)
Input Current 1
VIN at no load
Input Current 2
VOUT in switch off
condition
EXT “H” Output Current
VE XT = V OUT – 0.4V
VOUT ≤ 3.5V
3.5V < V OU T ≤ 5V
VE XT = 0.4V
VOUT ≤ 3.5V
3.5V < V OU T ≤ 5V
VOUT ≤ 3.5V
(2)
3.5V < V OU T ≤ 5V
(2)
(2)
(1)
Maximum Oscillator Frequency
FMAX
Oscillator Duty Cycle
DOSC
VE XT ” H ” side
Typ
Max Units
−2
--
---
+2
7
%
V
--
0.85
1.0
V
---
30
60
50
90
μA
--
6
10
μA
−1.5
−2
---
---
mA
1.5
2
80
--120
--160
kHz
65
60
75
70
85
80
%
%
(1)
(1)
EXT “L” Output Current
Min
(2)
VOUT = 2.5V to 5V
VOUT = 1.5V to 2.4V
mA
Notes:
(1)Unless otherwise provided, VIN = 1.8V, VSS = 0V, IOUT = 10mA, TOPT = 25° C, and use External Circuit of Typical
Application
(2)Unless otherwise provided, VIN = 3V, VSS= 0V, IOUT = 10mA, TOPT = 25° C, and External Circuit of Typical Application
DS9261/A-15 April 2010
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5
RT9261/A
Electrical Characteristics
Parameter
Output Voltage Accuracy
Input Voltage
Start-up Voltage
Hold-on Voltage
Efficiency
Input Current 1
Input Current 2
LX Switching Current
LX Leakage Current
(Refer to Figure 3)
Sym bol
ΔVOUT
VIN
VST
VHO
IOUT = 1mA, VIN : 0 → 2V
IOUT = 1mA, VIN : 2 → 0V
(1)
V OUT ≤ 3.5V
(2)
3.5V < VOUT ≤ 5V
(1)
VOUT ≤ 3.5V
VIN at no load
3.5V < V OUT ≤ 5V (2)
(1)
VOUT in switch VOUT ≤ 3.5V
(2)
off condition
3.5V < V OUT ≤ 5V
(1)
VOUT ≤ 3.5V
ISWITCHING V LX = 0.4V
(2)
3.5V < V OUT ≤ 5V
VL X = 6V
ILEAKAGE
VIN = V OUT × 0.9
EN “H” Level
VIN = V OUT × 0.9
EN “ L” Level
EN “ H” Input Current
EN “ L“ Input Current
Maximum Oscillator Frequency FMAX
Oscillator Duty Cycle
VL X Voltage Limit
Test Conditions
DOSC
EN = V OUT
EN = 0V
On (VLX ” L” ) VOUT = 2.5V to 5V
side
VOUT = 1.5V to 2.4V
LX switch on
Min
Typ
Max
Units
−2
--0.7
----
--0.85
-75
85
15
+2
7
1.0
---18
%
V
V
V
---60
80
-0.4 x
V OU T
---
18
5
6
----
24
8
10
--0.5
--
--
---
0.2
0.5
−0.5
80
-120
-160
μA
μA
kHz
65
60
0.65
75
70
0.8
85
80
1.0
%
%
V
%
μA
μA
mA
μA
V
V
Notes:
(1)Unless otherwise provided, VIN = 1.8V, VSS = 0V, IOUT = 10mA, TOPT = 25°C, and use External Circuit of Typical
Application
(2)Unless otherwise provided, VIN = 3V, VSS= 0V, IOUT = 10mA, TOPT = 25°C, and External Circuit of Typical Application
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DS9261/A-15 April 2010
RT9261/A
Electrical Characteristics
Parameter
(Refer to Figure 4)
Symbol
Test Conditions
Min
Typ
Max Units
Output Voltage Accuracy
ΔV OUT
−2
--
+2
%
Input Voltage
VIN
--
--
7
V
Start-up Voltage
VST
V
Efficiency
IOUT = 1mA, V IN : 0 → 2V
(1)
V OUT ≤ 3.5V
--
0.85
1.0
--
75
--
3.5V < VOUT ≤ 5V
--
85
--
--
30
50
--
60
90
--
6
10
−1.5
--
--
−2
--
--
1.5
--
--
2
--
--
(2)
VOUT ≤ 3.5V
(1)
Input Current 1
VIN at no load
Input Current 2
VOUT in switch VOUT ≤ 3.5V
(2)
off condition
3.5V < V OUT ≤ 5V
EXT “H” Output Current
VEXT = VOUT – VOUT ≤ 3.5V
(2)
0.4V
3.5V < V OUT ≤ 5V
3.5V < V OUT ≤ 5V
(2)
%
μA
(1)
(1)
VOUT ≤ 3.5V (1)
μA
mA
EXT “L” Output Current
VEXT = 0.4V
EN “H” Level
VIN = V OUT × 0.9
0.4× VOUT
--
--
V
EN “ L” Level
--
--
0.2
V
EN “ H” Input Current
VIN = V OUT × 0.9
EN = V OUT
--
--
0.5
μA
EN “ L“ Input Current
EN = 0V
−0.5
--
--
μA
Maximum Oscillator Frequency
Oscillator Duty Cycle
VLX Voltage Limit
3.5V < V OUT ≤ 5V
(2)
FMAX
DOSC
On (VLX ” L” )
side
LX switch on
mA
80
120
160
kHz
V OUT = 2.5V to 5V
65
75
85
%
V OUT = 1.5V to 2.4V
60
70
80
%
0.65
0.8
1.0
V
Notes:
(1)Unless otherwise provided, VIN = 1.8V, VSS = 0V, IOUT = 10mA, TOPT = 25°C, and use External Circuit of Typical
Application
(2)Unless otherwise provided, VIN = 3V, VSS= 0V, IOUT = 10mA, TOPT = 25°C, and External Circuit of Typical Application
DS9261/A-15 April 2010
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7
RT9261/A
Typical Operating Characteristics
Output Current vs. Ripple Voltage
Start-up/Hold-on Voltage vs. Output Current
120
1.2
Vstart
Ripple Voltage (mV p-p)
Start-up/Hold-on Voltage
Vstart/Vhold (V)
1.4
1
0.8
Vhold
0.6
0.4
0.2
RT9261
VOUT = 2.7V
100
80
2.0V
60
2.5V
1.5V
40
0.9V
20
0
0
0
10
20
30
40
0
50
20
60
80
100
Output Voltage vs. Temperature
Output Voltage vs. Output Current
2.90
3
2.0V
1.5V
2.5
0.9V
2.5V
1.0V
2.85
Output Voltage (V)
Output Voltage (V)
40
Output Current (mA)
Output Current (mA)
2
1.5
1
0.5
RT9261
VOUT = 2.7V
2.80
2.75
2.70
2.65
RT9261
VOUT = 2.7V
2.60
0
0
20
40
60
80
-40
100
-20
Efficiency vs. Output Current
70
80
2.5V
1.5V
1.0V
0.9V
50
40
30
20
RT9261
VOUT = 2.7V
10
Supply Current (uA)
60
2.0V
60
20
40
60
80
Supply Current vs. Temperature
90
70
0
Temperature (° C)
Output Current (mA)
Efficiency (%)
RT9261
VOUT = 2.7V
RT9261
VOUT = 2.7V
50
40
30
20
Input Current 2
Input Current 1
10
0
0
0
20
40
60
Output Current (mA)
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8
80
100
-40
-20
0
20
40
60
80
Temperature (° C)
DS9261/A-15 April 2010
Maximum Oscillator Frequency
vs. Temperature
Output Voltage vs. Output Current
3
160
140
2.5V
1.5V
2.5
120
Output Voltage (V)
Maximum Oscillator Frequency (kHz) A
RT9261/A
100
80
60
40
2.0V
0.9V
2
1.5
1
0.5
RT9261
VOUT = 2.7V
20
1.0V
0
RT9261A
VOUT = 2.7V
0
-40
-20
0
20
40
60
80
0
30
Temperature (° C)
60
90
120
Efficiency vs. Output Current
Oscillator Duty Cycle vs. Temperature
100
80
2.5V
90
60
Efficiency (%)
Oscillator Duty Cycle (%)
70
80
70
2.0V
0.9V
50
1.5V
1.0V
40
30
20
60
RT9261
VOUT = 2.7V
RT9261A
VOUT = 2.7V
10
50
0
-40
-20
0
20
40
60
80
0
30
Temperature (° C)
60
90
120
150
Output Current (mA)
Start-up/Hold-on Voltage vs. Output Current
Output Current vs. Ripple Voltage
1.6
120
1.4
Ripple Voltage (mV p-p)
Start-up/Hold-on Voltage1
Vstart/Vhold (V)
150
Output Current (mA)
Vstart
1.2
1
0.8
Vhold
0.6
0.4
RT9261A
VOUT = 2.7V
0.2
0
100
2.5V
80
2.0V
60
1.5V
40
0.9V
20
RT9261A
VOUT = 2.7V
0
0
30
60
90
Output Current (mA)
DS9261/A-15 April 2010
120
150
0
30
60
90
120
150
Output Current (mA)
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RT9261/A
Outline Dimension
H
D
L
B
C
b
A
A1
e
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
0.889
1.295
0.035
0.051
A1
0.000
0.152
0.000
0.006
B
1.397
1.803
0.055
0.071
b
0.356
0.559
0.014
0.022
C
2.591
2.997
0.102
0.118
D
2.692
3.099
0.106
0.122
e
0.838
1.041
0.033
0.041
H
0.080
0.254
0.003
0.010
L
0.300
0.610
0.012
0.024
SOT-23-5 Surface Mount Package
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DS9261/A-15 April 2010
RT9261/A
D
D1
A
B
C
C1
e
e
H
A
b
Symbol
b1
b
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
1.397
1.600
0.055
0.063
b
0.356
0.483
0.014
0.019
B
2.388
2.591
0.094
0.102
b1
0.406
0.533
0.016
0.021
C
3.937
4.242
0.155
0.167
C1
0.787
1.194
0.031
0.047
D
4.394
4.597
0.173
0.181
D1
1.397
1.753
0.055
0.069
e
1.448
1.549
0.057
0.061
H
0.356
0.432
0.014
0.017
3-Lead SOT-89 Surface Mount
Richtek Technology Corporation
Richtek Technology Corporation
Headquarter
Taipei Office (Marketing)
5F, No. 20, Taiyuen Street, Chupei City
8F, No. 137, Lane 235, Paochiao Road, Hsintien City
Hsinchu, Taiwan, R.O.C.
Taipei County, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Tel: (8862)89191466 Fax: (8862)89191465
Email: marketing@richtek.com
Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit
design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be
guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.
DS9261/A-15 April 2010
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