首页 |元器件品牌

L1937 [UTC]

WHITE LED STEP-UP CONVERTER; 白光LED升压转换器
L1937
型号： L1937
厂家： Unisonic Technologies    Unisonic Technologies
描述：

WHITE LED STEP-UP CONVERTER
白光LED升压转换器

转换器 升压转换器
文件： 总7页 (文件大小：60K)
中文：  中文翻译
下载：  下载PDF数据表文档文件
 查看货源
UTC L1937  
LINEAR INTEGRATED CIRCUIT  
WHITE LED STEP-UP  
CONVERTER  
1
2
3
DESCRIPTION  
The UTC L1937 is a step-up DC/DC converter  
5
specifically designed to drive white LEDs with  
constant current. The device can drive two, three or  
four LEDs in series from Li-Ion cell. Series  
a
4
a
SOT-25  
connection of the LEDs provides identical LED  
currents resulting in uniform brightness and  
eliminating the need for ballast resistors. The UTC  
LT1937 switches at 1.2MHz, allowing the use of tiny  
external components. The output capacitor can be as  
small as 0.22 μF, saving space and cost versus  
alternative solutions. A low 95mV feedback voltage  
minimizes power loss in the current setting resistor for  
better efficiency.  
1
SOT-363  
FEATURES  
* Inherently Matched LED Current  
* High Efficiency: 84% Typical  
* Drives Up to Four LEDs from a 3.2V Supply  
* Drives Up to Six LEDs from a 5V Supply  
* 36V Rugged Bipolar Switch  
*Pb-free plating product number: L1937L  
* Fast 1.2MHz Switching Frequency  
* Uses Tiny 1mm Tall Inductors  
* Requires Only 0.22μFOutput Capacitor  
APPLICATIONS  
* Marking code: LTCG  
* Cellular Phones  
* PDAs, Handheld Computers  
* Digital Cameras  
* MP3 Players  
* GPS Receivers  
PIN FUNCTION  
PIN NO. PIN NO.  
(SOT-25) (SOT-363).  
PIN NAME  
SYMBOL  
FUNCTION  
Connect inductor/diode here. Minimize trace area at this pin to  
reduce EMI.  
SW  
1
2
Switch  
GND  
Ground  
Connect directly to local ground plane.  
Reference voltage is 95mV. Connect cathode of lowest LED and  
resistor here. Calculate resistor value according to the formula:  
RFB = 95mV/ILED  
FB  
3
4
Feedback  
Connect to 1.5V or higher to enable device;0.4V or less to  
disable device.  
Shutdown  
SHDN  
VIN  
5
6
5
Input Supply  
Ground  
Input Supply Pin. Must be locally bypassed.  
Connect to Pin 2 and to local ground plane  
GND  
UTC UNISONIC TECHNOLOGIES CO., LTD.  
1
QW-R103-021,A  
UTC L1937  
LINEAR INTEGRATED CIRCUIT  
BLOCK DIAGRAM  
V
IN  
FB  
SW  
1
( PIN 6 FOR SOT-363  
PACKAGE )  
3
5
COMPARATOR  
A2  
DRIVER  
-
-
95mV  
A1  
V
1.25V  
REF  
Q
Q1  
R
+
S
+
Rc  
Cc  
+
-
0.2Ω  
Σ
RAMP  
GENERATOR  
SHDN  
4
GND  
SHUTDOWN  
2
1.2MHz  
OSCILIATOR  
( PINS 2 AND 5 FOR  
SOT-363 PACKAGE )  
ABSOLUTE MAXIMUM RATINGS  
PARAMETER  
SYMBOL  
RATINGS  
UNIT  
Input Voltage  
V
IN  
SW  
FB  
SHDN  
10  
36  
V
V
SW Voltage  
V
FB Voltage  
V
10  
V
SHDN Voltage  
V
10  
V
℃
℃
℃
℃
Operating Temperature  
Storage Temperature  
Maximum Junction Temperature  
Lead Temperature (Soldering, 10 sec)  
Topr  
Tstg  
-40 ~ +85  
-65 ~ +150  
125  
Tj  
TLead  
300  
ELECTRICAL CHARACTERISTICS (Ta=25℃, VIN=3V, VSHDN=3V, unless otherwise noted.)  
PARAMETER  
SYMBOL  
TEST CONDITIONS MIN TYP MAX UNIT  
Operating Voltage  
V
IN  
FB  
FB  
10  
104  
100  
2.5  
1.0  
V
Feedback Voltage  
FB Pin Bias Current  
Supply Current  
V
I
SW=100mA,Duty Cycle=66%  
86  
10  
95  
45  
mV  
nA  
mA  
µA  
I
1.9  
0.1  
1.2  
90  
Icc  
SHDN=0V  
Switching Frequency  
Maximum Duty Cycle  
Switch Current Limit  
Switch VCESAT  
f
osc  
0.8  
85  
1.6 MHz  
DC  
%
I
SW  
CESAT(SW)  
SW(OFF)  
IH  
IL  
SHDN  
320  
350  
0.01  
mA  
mV  
V
I
SW=250mA  
SW=5V  
Switch Leakage Current  
SHDN Voltage High  
SHDN Voltage Low  
SHDN Pin Bias Current  
I
V
5
µA  
V
V
1.5  
V
0.4  
V
I
65  
µA  
UTC UNISONIC TECHNOLOGIES CO., LTD.  
2
QW-R103-021,A  
UTC L1937  
LINEAR INTEGRATED CIRCUIT  
TYPICAL APPLICATIONS  
Conversion Efficiency  
90  
L1  
D1  
22μF  
VIN  
3V ~ 5V  
85  
C1  
1μF  
C2  
0.22μF  
LED 1  
LED 2  
LED 3  
80  
V
IN  
SW  
FB  
15mA  
VIN=3V  
V
IN=3.6V  
75  
70  
65  
60  
OFF ON  
SHDN  
GND  
R1  
6.34Ω  
Li-Ion Powered Driver for Three White LEDs  
10  
LED CURRENT (mA)  
15  
5
20  
0
Two LED Efficiency  
86  
L
22μH  
V
IN=3.6V  
84  
82  
80  
D
V
IN  
3V ~ 5V  
C
1μF  
IN  
C
1μF  
OUT  
V
DC  
V
IN=3V  
DIMMING  
V
IN  
SW  
90k  
5k  
78  
76  
SHDN  
GND  
FB  
R1  
2Ω  
74  
72  
70  
Li-Ion to Two White LEDs  
20  
LED CURRENT (mA)  
30  
10  
40  
0
UTC UNISONIC TECHNOLOGIES CO., LTD.  
3
QW-R103-021,A  
UTC L1937  
LINEAR INTEGRATED CIRCUIT  
Three LED Efficiency  
90  
L
22μH  
D
85  
V
IN  
3V ~ 5V  
C
1μF  
IN  
C
OUT  
V
DC  
0.22μF  
DIMMING  
80  
75  
70  
V
IN  
SW  
V
IN=3V  
V
IN=3.6V  
90k  
5k  
UTC LT1937  
SHDN FB  
GND  
R1  
4Ω  
65  
60  
Li-Ion to Three White LEDs  
10  
LED CURRENT (mA)  
15  
5
20  
0
Five LED Efficiency  
85  
80  
75  
L
22μH  
D
V
IN  
3V ~ 5V  
C
1μF  
IN  
C
OUT  
V
DC  
0.22μF  
DIMMING  
VIN  
SW  
V
IN=3V  
90k  
5k  
SHDN  
GND  
FB  
R1  
4Ω  
V
IN=3.6V  
70  
65  
Li-Ion to Five White LEDs  
2
6
0
8
12  
4
10  
LOAD CURRENT (mA)  
UTC UNISONIC TECHNOLOGIES CO., LTD.  
4
QW-R103-021,A  
UTC L1937  
LINEAR INTEGRATED CIRCUIT  
Seven LED Efficiency  
85  
L
22μH  
D
VIN  
5V  
80  
C
1μF  
IN  
C
OUT  
V
DC  
0.22μF  
DIMMING  
SW  
VIN  
90k  
5k  
75  
70  
65  
SHDN  
GND  
FB  
R1  
4Ω  
5V to Seven White LEDs  
0
5
10  
15  
LOAD CURRENT (mA)  
Four LED Efficiency  
85  
80  
75  
70  
L
22μH  
D
V
IN  
C
1μF  
IN  
3V ~ 5V  
C
OUT  
VDC  
0.22μF  
DIMMING  
VIN=3V  
VIN  
SW  
FB  
VIN=3.6V  
90k  
5k  
SHDN  
GND  
R1  
4Ω  
Li-Ion to Four White LEDs  
65  
0
5
10  
LOAD CURRENT (mA)  
15  
20  
UTC UNISONIC TECHNOLOGIES CO., LTD.  
5
QW-R103-021,A  
UTC L1937  
LINEAR INTEGRATED CIRCUIT  
TYPICAL PERFORMANCE CHARACTERISTICS  
Quiescent Current  
2.2  
SHDN Pin Bias Current  
400  
-50℃  
2.0  
350  
300  
250  
200  
150  
1.8  
100℃  
25℃  
1.6  
SHDN=10V  
1.4  
1.2  
1.0  
0.8  
0.6  
0.4  
0.2  
0
SHDN=3.6V  
SHDN=2.7V  
SHDN=3V  
100  
50  
0
-50  
2
4
0
6
8
10  
0
100  
100  
100  
-25  
25  
50  
75  
V
IN (V)  
TEMPERATURE (℃)  
Switching Frequency  
Feedback Bias Current  
1.4  
1.2  
60  
50  
40  
30  
1.0  
0.8  
0.6  
0.4  
20  
10  
0
0.2  
0
-50  
-25  
0
-25  
0
25  
50  
75  
100  
-50  
25  
50  
75  
TEMPERATURE (℃)  
TEMPERATURE (℃)  
Efficiency vs Temperature  
Current Limit vs Duty Cycle  
350  
300  
250  
85  
V
IN=3.6V  
3 LEDs  
I
LED=20mA  
84  
83  
ILED=15mA  
200  
150  
ILED=10mA  
82  
81  
80  
100  
50  
0
0
100  
20  
60  
DUTY CYCLE (%)  
80  
-50  
50  
0
40  
TEMPERATURE (℃)  
UTC UNISONIC TECHNOLOGIES CO., LTD.  
6
QW-R103-021,A  
UTC L1937  
LINEAR INTEGRATED CIRCUIT  
UTC assumes no responsibility for equipment failures that result from using products at values that  
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or  
other parameters) listed in products specifications of any and all UTC products described or contained  
herein. UTC products are not designed for use in life support appliances, devices or systems where  
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in  
whole or in part is prohibited without the prior written consent of the copyright owner. The information  
presented in this document does not form part of any quotation or contract, is believed to be accurate  
and reliable and may be changed without notice.  
UTC UNISONIC TECHNOLOGIES CO., LTD.  
7
QW-R103-021,A  

相关型号：

L1937(SOT-363)

 Display Driver, PDSO6
UTC

L1939

 300 レm emission spot, no electrode in emission area
HAMAMATSU

L1939-04

 300 レm emission spot, no electrode in emission area
HAMAMATSU

L1939_15

 Infrared LED
HAMAMATSU

L193GD

 RECTANGULAR LED LAMP,GREEN,DIFFUSED,LED-6B
KINGBRIGHT

L193ID

 RECTANGULAR LED LAMP,RED,DIFFUSED,LED-6B
KINGBRIGHT

L193YD

 RECTANGULAR LED LAMP,YELLOW,DIFFUSED,LED-6B
KINGBRIGHT

L1A

 Surface Mount Glass Passivated Rectifier
GOOD-ARK

L1A23A150MAB2F

 L1A23A150MAB2F, CHIP
KYOCERA AVX

L1A23A3R9M4X2F

 L1A23A3R9M4X2F, CHIP
KYOCERA AVX

L1A23A8R2KAB2A

 L1A23A8R2KAB2A, CHIP
KYOCERA AVX

L1A23C272K4X2A

 L1A23C272K4X2A, CHIP
KYOCERA AVX
©2020 ICPDF网 联系我们和版权申明