SP1937
DC-DC Step-Up Converter for White LED
DESCRIPTION
The SP1937 is a step-up DC/DC converter for white
LED driver with constant current. The device can driver
one to four LEDs in series from a single cell Lithium
Ion battery. Internal functions include current limiting;
thermal shutdown and soft-start to prevent damage
operate status. The SP1937 DC/DC converter operates
at 1.2MHz and low output capacitor as small as 0.22uF;
apply to Lithium-Ion powered systems. A low 95mV
(Typ) reference voltage minimizes power loss in the
current setting resistor for better efficiency.
APPLICATIONS
Battery Power Equipment
Notebook Computers
PDA
Cellular Phone
Digital Cameras
MP3 Players
GPS Receivers
FEATURES
Fast 1.2MHz Switching Frequency
High Efficiency up to 85%
Drives up to Four LEDs From 3.2V Supply
Low Quiescent Current
Disconnects LEDs in Shutdown Mode
Internal Over Temperature and Current Limiting
Shutdown Function
36V Rugged Bipolar Switch
Small Package SOT-23-5L & SOT-353
PIN CONFIGURATION
SOT-23-5L
SOT-353 ( SC-70-5L )
PART MARKING
SOT-23-5L
SOT-353 ( SC-70-5L )
2009/06/15
Ver.5
Page 1
SP1937
DC-DC Step-Up Converter for White LED
TYPICAL APPLCATION CIRCUIT
PIN DESCRIPTION
SP1937S25RG / SP1937S25RGB
Pin
Symbol
Description
1
SW
Switch Pin.
2
GND
Ground Pin
3
FB
Feedback Pin.
4
SHDN
Shutdown Pin. Active-low enable
5
VIN
Supply Voltage Input
SP1937S36RG / SP1937S36RGB
Pin
Symbol
Description
1
SW
Switch Pin.
2
GND
Ground Pin
3
FB
Feedback Pin.
4
SHDN
Shutdown Pin. Active-low enable
5
GND
Ground Pin
6
VIN
Supply Voltage Input
ORDERING INFORMATION
Part Number
Package
SP1937S25RG
SOT-23-5L
SP1937S25RGB
SOT-23-5L
SP1937S35RG
SOT-353 ( SC-70-5L )
SP1937S35RGB
SOT-353 ( SC-70-5L )
※
Week Code : A ~ Z( 1 ~ 26 ) ; a ~ z( 27 ~ 52 )
※
SP1937S25RG : Tape Reel ; Pb – Free
※
SP1937S25RGB : Tape Reel ; Pb – Free ; Halogen - Free
※
SP1937S35RG : Tape Reel ; Pb – Free
※
SP1937S35RGB : Tape Reel ; Pb – Free ; Halogen - Free
Part
Marking
97YW
97YW
97YW
97YW
2009/06/15
Ver.5
Page 2
SP1937
DC-DC Step-Up Converter for White LED
BLOCK DIAGRAM
ABSOULTE MAXIMUM RATINGS
(T
A
=25
℃
Unless otherwise specified)
Parameter
DC Supply Voltage
SW Voltage
FB Voltage
SHDN Voltage
Operating Temperature
Maximum Junction Temperature
Storage Temperature
Symbol
V
IN
V
SW
V
FB
V
SHDN
T
OPR
T
J(Max)
T
S
Value
20
36
10
10
-40½85
125
-65½150
Unit
V
V
V
V
℃
℃
℃
The IC has a protection circuit against static electricity. Do not apply high static electricity or high voltage that
exceeds the performance of the protection circuit to the IC.
2009/06/15
Ver.5
Page 3
SP1937
DC-DC Step-Up Converter for White LED
ELECTRICAL CHARACTERISTICS
(T
A
=25
℃
, V
IN
=3V, V
SHDN
=3V, Unless otherwise specified)
Parameter
Operating Voltage
Feedback Voltage
FB Pin Bias Current
Supply Current
Switching Frequency
Maximum Duty Cycle
Switch Current Limit
Switch Leakage Current
Switch Vcesat
SHDN Voltage High
SHDN Voltage Low
SHDN Pin Bias Current
Conditions
I
SW
=100mA, Duty Cycle = 66%
V
SHDN
= 0V
0.8
V
SW
= 5V
I
SW
= 200mA
1.5
0.4
90
Min.
2.5
86
Typ.
Max.
20.0
110
150
3.5
1.0
1.6
5
Unit
V
mV
nA
mA
μA
MHz
%
mA
μA
mV
V
V
uA
2.8
0.1
1.2
85
320
0.01
150
2009/06/15
Ver.5
Page 4
SP1937
DC-DC Step-Up Converter for White LED
TYPICAL PERFORMERCE CHARACTERISTICS
2009/06/15
Ver.5
Page 5
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