Synchronous Step-Up DC/DC Converter with PFM Control
CE8401 Series
LESHAN RADIO COMPANY, LTD.
Synchronous Step-Up DC/DC
Converter with PFM Control
LR8401 Series
INTRODUCTION
The LR8 401 Series is a Synchronous
step-up DC/DC Converter with PFM Control.
With the LR8 401 Series, a step-up
switching DC/DC converter can be configured
by using an external coil, capacitor. The
built-in MOSFET is turned off by a protection
circuit when the voltage at the LX pin exceeds
the limit to prevent it from being damaged.
FEATURES
External parts: Coil, capacitor
Output voltage: Settable to between 2.1V
to 5.5 V in 0.1 V steps
Maximum Oscillation frequency:300KHz
Accuracy of ±2%
High efficiency：95%
APPLICATIONS
Digital cameras
Electronic notebooks and PDAs
Portable CD/MD players
Cameras, video equipment,
Communications equipment
Power supply for microcomputers
BLOCK DIAGRAM
ORDER INFORMATION
LR8401①②③④
LX
Current
Limiting
comparator
DESIGNATOR
VOUT
SYMBOL
A
DESCRIPTION
Standard LX
With shutdown, LX
Output Voltage
（2.1½5.5）
e.g.：3.0V=②:3;
③:0
Package：SOT-23-3/5
Package：SOT-23
Package：SOT-89
Package：TO92
①
B
buffer
PFM
control
②③
Error
Amplifier
ref
Integer
M
MB
P
T
EN
Chip
Enable
OSC
VSS
④
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LESHAN RADIO COMPANY, LTD.
PIN CONFIGURATION
Table 1
PIN NO.
1
2
3
LR8401A Series（SOT-23-3/SOT-23 PKG）
FUNCTION
Output voltage pin
GND pin
External inductor connection pin
PIN NAME
V
OUT
V
SS
LX
Table 2
PIN NO.
1
2
3
4
5
Table 3
PIN NO.
1
2
3
Table 4
LR8401B Series（SOT-23-5 PKG）
FUNCTION
Shutdown pin
“H”: Normal operation
“L”: Step-up stopped
Output voltage pin
(N.C.)
GND pin
External inductor connection pin
PIN NAME
EN
V
OUT
NC
V
SS
LX
LR8401A Series
（SOT-89-3
PKG）
FUNCTION
GND pin
Output voltage pin
External inductor connection pin
PIN NAME
V
SS
V
OUT
LX
LR8401A Series
（TO-92
PKG）
FUNCTION
GND pin
Output voltage pin
External inductor connection pin
TO-92
Bottom view
1 2 3
PIN NO.
1
2
3
PIN NAME
V
SS
V
OUT
LX
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LESHAN RADIO COMPANY, LTD.
ABSOLUTE MAXIMUM RATINGS
(Unless otherwise specified, Ta=25°C)
PARAMETER
V
OUT
Pin Voltage
EN
LX
LX
Power
Dissipation
Pin Voltage
Pin Voltage
Pin Current
SOT-23
SOT23-3/SOT-23-5
SOT-89-3
TO-92
Operating Temperature
Storage Temperature
Soldering Temperature & Time
T
opr
T
stg
T
solder
PD
SYMBOL
V
OUT
EN
V
LX
I
LX
RATINGS
V
SS
-0.3 ~ V
SS
+8
V
SS
-0.3 ~ V
SS
+8
V
SS
-0.3 ~ V
SS
+8
1000
250
250
500
500
-40 ~+85
-40 ~+125
260°C, 10s
UNITS
V
V
V
mA
mW
mW
mW
mW
°C
°C
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, Ta=25°C)
PARAMETER
SYNBOL
V
OUT
V
IN
V
ST1
I
SS
I
SS2
I
SSS
f
OSC
CONDITIONS
－
－
I
OUT
= 1 mA
V
IN
=1.8V,V
OUT
=3.0V
V
OUT
=V
OUT
＋0.5
V
V
EN
= 0 V
V
OUT
= 0.95×V
OUT
，
measure
waveform at LX pin
MIN
V
OUT(S)
×0.98
－
－
－
－
－
TYP
V
OUT
－
－
15
6
－
300
MAX
V
OUT(S)
×1.02
5
0.9
-
10
1.0
UNITS
V
V
V
µA
µA
µA
KHz
Output Voltage
Input Voltage
Operation Start Voltage
Input Current At No Load
Current Consumption 2
Current Consumption
During Shutdown
Maximum Oscillation
Frequency
Duty Ratio 1
Efficiency
Shutdown Pin Input
Voltage
Shutdown Pin Input
Current
Duty1
EFFI
V
SH
V
SL1
I
SH
I
SL
V
OUT
= 0.95×V
OUT
，
measure waveform at
LX pin
V
OUT
=0.95×V
OUT
，
judge
oscillation at LX pin
V
OUT
= 0.95×V
OUT
，
judge stop at LX pin
V
EN
＝6V
V
EN
＝0V
70
78
90
85
%
%
0.75
－
-0.1
-0.1
－
－
－
－
－
0.3
0.1
0.1
V
V
µA
µA
Remark：V
OUT(S)
specified above is the set output voltage value, and V
OUT
is the typical value of
the actual output voltage
.
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LESHAN RADIO COMPANY, LTD.
■
STANDARD CIRCUITS
Component:
Inductor：47uH(Sumida)
Capacitor：47uF/16V(Tantalum)
1、
LR8401A：
2、LR8401B：
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LESHAN RADIO COMPANY, LTD.
TYPICAL PERFORMANCE CHARACTERISTICS
Cin=Cout=100uF
L=47uH
5/10
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