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Электронный компонент: RT9261B-15CB

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Preliminary
RT9261B
DS9261B-03 September 2001
www.richtek-ic.com.tw
1
VFM Step-up DC/DC Converter
General Description
The RT9261B Series are VFM Step-up DC/DC
converter ICs with ultra low supply current by CMOS
process and suitable for use with battery-powered
instruments.
The RT9261B 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 with the
RT9261B IC and only three external components.
The CE pin enables the circuit to set the standby
supply current at a maximum of 0.5
A.
Ordering Information
RT9261B-
Features
Minimal Number of External Components
(Only an Inductor, a Diode, and a Capacitor)
Ultra Low Input Current (6.5



A at Switch Off)
Capable of Supplying 50mA Output Current
with Internal Switch



2% Output Voltage Accuracy
Low Ripple and Low Noise
Low Start-up Voltage, 0.8V at 1mA
80% Efficiency with Low Cost Inductor
+50 ppm/



C Low Temperature-Drift
SOT-89 and SOT-25 Small Packages
Applications
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 appliances, which require
higher voltage than that of batteries used in the
appliances
Pin Configurations
Part Number
Pin Configurations
RT9261B-
CX
(Plastic SOT-89)
TOP VIEW
1. GND
2. VOUT (TAB)
3. LX
RT9261B-
CB
(Plastic SOT-25)
TOP VIEW
1. CE
2. VOUT
3. NC
4. GND
5.
LX
Operating temperature range
C: Commercial standard
Package type
B : SOT-25
X : SOT-89
Output voltage
15 : 1.5V
16 : 1.6V
:
49 : 4.9V
50 : 5.0V
5
4
3
2
1
1
2
3
RT9261B
Preliminary
www.richtek-ic.com.tw
DS9261B-03 September 2001
2
Typical Application Circuit
* L1 ranges from 27
H to 120H
Pin Description
Pin No.
-xxCX
-xxCB
Pin Name
Pin Function
1
4
GND
Ground
2
2
VOUT
Output Voltage
3
5
LX
Pin for Switching
--
1
CE
Chip Enable (Active High)
--
3
NC
No Connection
Function Block Diagram
VOUT
Vref
Chip Enable
OSC 190kHz
VFM Control
Buffer
VLX Limiter
Error Amp.
CE
LXSW
+
-
GND
LX
V
OUT
Co
L1
V
IN
LX
VOUT
GND
D1
22
F
27
H
1N5819
+
-
RT9261B
D1
V
OUT
Co
L1
V
IN
LX
VOUT
GND
CE
1N5819
22
F
27
H
+
-
RT9261B
Preliminary
RT9261B
DS9261B-03 September 2001
www.richtek-ic.com.tw
3
Absolute Maximum Ratings
Output Voltage
8V
LX Pin Voltage
8V
CE Pin Voltage
(1)
-0.3 to V
OUT
+0.3V
LX Pin Output Current
400mA
Power Dissipation, P
D
@ T
A
= 25
C
SOT-89
0.5W
SOT-25
0.25W
Package Thermal Resistance
SOT-89,
JC
100
C/W
SOT-89,
JA
300
C/W
SOT-25,
JA
250
C/W
Operating Temperature Range
-20 to +85
C
Storage Temperature Range
-65
C to 150C
Lead Temperature (Soldering, 10 sec.)
260
C
Notes: (1) Applicable to RT9261B-xxCB
Electrical Characteristics
(Refer to Fig. 1)
Parameter
Symbol
Test Conditions
Min
Typ
Max Units
Output Voltage Accuracy
V
OUT
-2
--
+2
%
Input Voltage
V
IN
--
--
7
V
Start-up Voltage
V
ST
I
OUT
= 1mA, V
IN
: 0
2V
--
0.8
1
V
Hold-on Voltage
V
HO
I
OUT
= 1mA, V
IN
: 2
0V
0.7
--
--
V
V
OUT
3.5V
(1)
--
24
36
Input Current 1
3.5V
< V
OUT
5V
(2)
To be measured at V
IN
in
continuous switching
--
36
45
A
Input Current 2
(1) (2)
To be measured at V
OUT
in
switch off condition
--
6.5
10
A
V
OUT
3.5V
(1)
--
18
36
Input Current 3
3.5V
< V
OUT
5V
(2)
To be measured at V
IN
in
no load (guaranteed by I
1
and I
2
)
--
20
45
A
V
OUT
3.5V
(1)
120
--
--
LX Switching Current
3.5V
< V
OUT
5V
(2)
I
SWITCHING
V
LX
= 0.4V
160
--
--
mA
LX Leakage Current
I
LEAKAGE
V
LX
= 6V
--
--
0.5
A
Maximum Oscillator Frequency
F
MAX
140
190
240
KHz
Oscillator Duty Cycle
D
OSC
On (V
LX
"L") side
65
75
85
%
Efficiency
--
80
--
%
V
LX
Voltage Limit
LX switch on
0.65
0.8
1.0
V
Notes:
(1) V
IN
= 1.8V, V
SS
= 0V, I
OUT
= 1mA, Topt = 25
C, and External Circuit of Typical Application
(2) V
IN
= 3V, V
SS
= 0V, I
OUT
= 1mA, Topt = 25
C, and External Circuit of Typical Application
RT9261B
Preliminary
www.richtek-ic.com.tw
DS9261B-03 September 2001
4
Electrical Characteristics
(Refer to Fig. 2)
Parameter
Symbol
Test Conditions
Min
Typ
Max Units
Output Voltage Accuracy
V
OUT
-2
--
+2
%
Input Voltage
V
IN
--
--
7
V
Start-up Voltage
V
ST
I
OUT
= 1mA, V
IN
: 0
2V
--
0.8
1
V
Hold-on Voltage
V
HO
I
OUT
= 1mA, V
IN
: 2
0V
0.7
--
--
V
Efficiency
--
80
--
%
V
OUT
3.5V
(1)
--
24
36
Input Current 1
3.5V
< V
OUT
5V
(2)
To be measured at V
IN
in
continuous switching
--
36
45
A
Input Current 2
(1) (2)
To be measured at V
OUT
in switch off condition
--
6.5
10
A
V
OUT
3.5V
(1)
--
18
36
Input Current 3
3.5V
< V
OUT
5V
(2)
To be measured at V
IN
in
no load (guaranteed by I
1
and
I
2
)
--
20
45
A
V
OUT
3.5V
(1)
120
--
--
LX Switching Current
3.5V
< V
OUT
5V
(2)
I
SWITCHING
V
LX
= 0.4V
160
--
--
mA
LX Leakage Current
I
LEAKAGE
V
LX
= 6V
--
--
0.5
A
CE "H" Level
V
IN
= V
OUT
* 0.9
0.4
V
OUT
--
--
V
CE "L" Level
V
IN
= V
OUT
* 0.9
--
--
0.2
V
CE "H" Input Current
CE = V
OUT
--
--
0.5
A
CE " L" Input Current
CE = 0V
-0.5
--
--
A
Maximum Oscillator Frequency
F
MAX
140
190
240
KHz
Oscillator Duty Cycle
D
OSC
On (V
LX
"L") side
65
75
85
%
V
LX
Voltage Limit
LX switch on
0.65
0.8
1.0
V
Notes:
(1) V
IN
= 1.8V, V
SS
= 0V, I
OUT
= 1mA, Topt = 25
C, and External Circuit of Typical Application
(2) V
IN
= 3V, V
SS
= 0V, I
OUT
= 1mA, Topt = 25
C, and External Circuit of Typical Application
Preliminary
RT9261B
DS9261B-03 September 2001
www.richtek-ic.com.tw
5
Typical Operating Charateristics
Output Current vs. Ripple Voltage
0
50
100
150
200
250
300
0
50
100
150
200
Output Current (mA)
R
i
p
p
l
e V
o
l
t
ag
e
(
m
V
p
-
p
)
V
OUT
= 3.3V
C
OUT
= 20uF
L = 47uH
1.0V
1.5V
2.0V
2.5V
3.0V
Output Current vs. Ripple Voltage
0
10
20
30
40
50
60
70
80
90
0
50
100
150
200
Output Current (mA)
R
i
p
p
l
e V
o
l
t
ag
e
(
m
V
p
-
p
)
V
OUT
= 3.3V
C
OUT
= 68uF
L = 47uH
1.0V
1.5V
2.0V
2.5V
3.0V
Output Current vs. Ripple Voltage
0
5
10
15
20
25
0
50
100
150
200
Output Current (mA)
R
i
p
p
l
e V
o
l
t
ag
e
(
m
V
p
-
p
)
V
OUT
= 3.3V
C
OUT
= 170uF
L = 47uH
1.0V
1.5V
2.0V
2.5V
3.0V
Start-up/Hold-on Voltage vs. Output Current
0
0.5
1
1.5
2
2.5
0
30
60
90
120
150
180
Output Current (mA)
S
t
a
r
t
-
u
p
/
H
ol
d
-
on
V
o
l
t
a
g
e V
s
t
a
r
t
/
V
h
o
l
d
(
V
)
V
OUT
= 3.3V
L = 47uH
V
start
V
hold
Efficiency vs. output Current
0
10
20
30
40
50
60
70
80
90
0
50
100
150
200
Output Current (mA)
E
f
fi
ci
e
n
cy
(
%
)
V
OUT
= 3.3V
L = 47uH
1.0V
1.5V
2.0V
2.5V
3.0V
Output Voltage vs. Output Current
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
50
100
150
200
Output Current (mA)
O
u
t
put
V
o
l
t
a
g
e

(
V
)
V
OUT
= 3.3V
L = 47uH
1.0V
1.5V
2.0V
2.5V
3.0V
RT9261B
Preliminary
www.richtek-ic.com.tw
DS9261B-03 September 2001
6
Start-up/Hold-on Voltage vs. Output Current
0
0.5
1
1.5
2
2.5
0
20
40
60
80
100
120
Output Current (mA)
S
t
a
r
t
-
up/
H
o
l
d-
o
n
V
o
l
t
a
g
e
V
s
t
a
r
t
/
V
ho
l
d
(
V
)
V
OUT
= 3.3V
L = 100uH
V
start
V
hold
Output Voltage vs. Output Current
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
50
100
150
200
Output Current (mA)
O
u
tp
u
t
Vo
l
t
a
g
e

(
V
)
V
OUT
= 3.3V
L = 100uH
1.0V
1.5V
2.0V
2.5V
3.0V
Output Current vs. Ripple Voltage
0
50
100
150
200
250
300
0
50
100
150
200
Output Current (mA)
R
i
p
p
l
e
V
o
l
t
ag
e
(
m
V
p
-
p
)
V
OUT
= 3.3V
C
OUT
= 20uF
L = 100uH
1.0V
1.5V
2.0V
2.5V
3.0V
Output Current vs. Ripple Voltage
0
10
20
30
40
50
60
70
80
90
0
50
100
150
200
Output Current (mA)
R
i
p
p
le
V
o
lt
a
g
e

(
m
V
p
-
p
)
V
OUT
= 3.3V
C
OUT
= 68uF
L = 100uH
1.0V
1.5V
2.0V
2.5V
3.0V
Output Current vs. Ripple Voltage
0
2
4
6
8
10
12
14
16
18
0
50
100
150
200
Output Current (mA)
R
i
p
p
l
e
V
o
l
t
ag
e
(
m
V
p
-
p
)
V
OUT
= 3.3V
C
OUT
= 170uF
L = 100uH
1.0V
1.5V
2.0V
2.5V
3.0V
Efficiency vs. output Current
0
10
20
30
40
50
60
70
80
90
100
0
50
100
150
200
Output Current (mA)
E
f
f
i
ci
e
n
cy
(
%
)
V
OUT
= 3.3V
L = 100uH
1.0V
1.5V
2.0V
2.5V
3.0V
Preliminary
RT9261B
DS9261B-03 September 2001
www.richtek-ic.com.tw
7
Package Information
Dimensions In Millimeters
Dimensions In Inches
Symbol
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
--
4.242
--
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
0.381
0.432
0.015
0.017
3-Lead SOT-89 Surface Mount
D
D1
C
C1
B
e
e
A
b
b1
b
A
H
RT9261B
Preliminary
www.richtek-ic.com.tw
DS9261B-03 September 2001
8
Dimensions In Millimeters
Dimensions In Inches
Symbol
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
0.102
0.254
0.004
0.010
L
0.356
0.610
0.014
0.024
SOT- 25 Surface Mount Package
b
B
C
D
L
H
A1
e
A
Preliminary
RT9261B
DS9261B-03 September 2001
www.richtek-ic.com.tw
9
RT9261B
Preliminary
www.richtek-ic.com.tw
DS9261B-03 September 2001
10
RICHTEK TECHNOLOGY CORP.
Headquarter
6F, No. 35, Hsintai Road, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5510047 Fax: (8863)5537749
RICHTEK TECHNOLOGY CORP.
Taipei Office (Marketing)
8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City
Taipei County, Taiwan, R.O.C.
Tel: (8862)89191466 Fax: (8862)89191465
Email: marketing@richtek-ic.com.tw