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LT1109CS8-12 参数 Datasheet PDF下载

LT1109CS8-12图片预览
型号: LT1109CS8-12
PDF下载: 下载PDF文件 查看货源
内容描述: 微低成本DC / DC转换器可调节和固定5V , 12V [Micropower Low Cost DC/DC Converter Adjustable and Fixed 5V, 12V]
分类和应用: 转换器开关光电二极管
文件页数/大小: 8 页 / 214 K
品牌: Linear [ Linear ]
 浏览型号LT1109CS8-12的Datasheet PDF文件第1页浏览型号LT1109CS8-12的Datasheet PDF文件第2页浏览型号LT1109CS8-12的Datasheet PDF文件第3页浏览型号LT1109CS8-12的Datasheet PDF文件第5页浏览型号LT1109CS8-12的Datasheet PDF文件第6页浏览型号LT1109CS8-12的Datasheet PDF文件第7页浏览型号LT1109CS8-12的Datasheet PDF文件第8页  
LT1109  
U W  
TYPICAL PERFOR A CE CHARACTERISTICS  
Minimum/Maximum  
Oscillator Frequency vs tON  
Quiescent Current  
Quiescent Current  
450  
400  
350  
300  
250  
200  
160  
150  
140  
130  
120  
110  
100  
90  
400  
380  
360  
340  
320  
300  
280  
260  
240  
220  
200  
T
= 25°C  
0°C T 70°C  
A
A
T
= 25°C  
A
80  
0
2
4
6
8
10 12 14 16 18 20  
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0  
–50 –25  
0
25  
50  
75  
100  
INPUT VOLTAGE (V)  
T
(µs)  
TEMPERATURE (°C)  
ON  
LT1109 • TPC09  
LT1109 • TPC08  
LT1109 • TPC10  
W
BLOCK DIAGRA S  
LT1109-5, -12 N8, S8 Package  
LT1109-5, -12 Z Package  
V
OUT  
V
FB SENSE  
IN  
R2  
250k  
SW  
R2  
250k  
COMPARATOR  
A1  
SW  
1.25V  
REFERENCE  
+
1.25V  
REFERENCE  
+
120kHz  
OSCILLATOR  
Q1  
120kHz  
OSCILLATOR  
A1  
Q1  
DRIVER  
DRIVER  
COMPARATOR  
R1  
R1  
LT1109 • TA04  
GND  
SHUTDOWN  
LT1109-5: R1 = 83k  
LT1109-12: R1 = 29k  
ON FIXED VERSION PIN 8 IS SENSE  
ON ADJUSTABLE VERSION PIN 8 IS FB AND R1 AND R2 ARE DISCONNECTED  
GND  
LT1109 • TA03  
U
LT1109Z OPERATIO  
The LT1109Z-5 and LT1109Z-12 are fixed output voltage  
step-up DC/DC converters in a 3-pin TO-92 package.  
Power for internal regulator circuitry is taken from the  
VOUT pin, a technique known as “bootstrapping.” Circuit  
operation can be best understood by referring to the block  
diagram. VOUT, attenuated by R1 and R2, is applied to the  
negative input of comparator A1. When this voltage falls  
below the 1.25V reference voltage, the oscillator is turned  
on and the power switch Q1 cycles at the oscillator  
frequency of 120kHz. Switch cycling alternately builds  
current in the inductor, then dumps it into the output  
capacitor, increasing the outputvoltage. WhenA1’s nega-  
tive input rises above 1.25V, it turns off the oscillator. A  
small amount of hysteresis in A1 obviates the need for  
frequencycompensationcircuitry.WhenQ1isoff,current  
into the VOUT pin drops to just 320µA. Quiescent current  
from the battery will be higher because the device oper-  
ates off the stepped-up voltage.  
4