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| 型号： | LT1109CS8-12#TR |
| 厂商： | Linear Technology |
| 文件页数： | 5/8页 |
| 文件大小： | 0K |
| 描述： | IC REG BOOST 12V 0.1A 8SOIC |
| 标准包装： | 2,500 |
| 类型： | 升压（升压） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 12V |
| 输入电压： | 3V，5V |
| 频率 - 开关： | 120kHz |
| 电流 - 输出： | 100mA |
| 同步整流器： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 8-SOIC |
LT1109
LT1109 S8 A D 8 OPER ATIO
The 8-pin versions of the LT1109 have separate pins for
V IN and SENSE or FB and also have a SHUTDOWN pin.
Separating the device V IN pin from the SENSE pin allows
the device to be powered from the (lower) input voltage
rather than the (higher) output voltage. Although quies-
cent current remains constant, quiescent power will be
reduced by using the 8-pin version since the quiescent
curren t flows from a lower voltage source. The SHUT-
DOWN pin disables the oscillator when taken to a logic “0.”
If left floating or tied high, the converter operates nor-
mally. With SHUTDOWN low, quiescent current remains
at 320 μ A.
A PPLICATI
Inductor Selection
S I FOR ATIO
where V D is the diode drop (0.5V for a 1N5818 Schottky).
A DC/DC converter operates by storing energy as mag-
netic flux in an inductor core, and then switching this
Energy required by the inductor per cycle must be equal or
greater than
( )
energy into the load. To operate as an efficient energy
transfer element, the inductor must fulfill three require-
ments. First, the inductance must be low enough for the
P L
F OSC
02
inductor to store adequate energy under the worst case
condition of minimum input voltage and switch-ON time.
The inductance must also be high enough so that maxi-
mum current ratings of the LT1109 and inductor are not
in order for the converter to regulate the output.
When the switch is closed, current in the inductor builds
according to
()
I L t = IN ? 1 – e L ?
( )
exceeded at the other worst case condition of maximum
input voltage and ON time. Additionally, the inductor core
must be able to store the required flux; i.e., it must not
V ? –R' t ?
R ' ? ?
03
saturate. At power levels generally encountered with
LT1109 designs, small ferrite surface-mount inductors
will function well. Lastly, the inductor must have suffi-
ciently low DC resistance so that excessive power is not
where R' is the sum of the switch equivalent resistance
(0.8 typical at 25 ° C) and the inductor DC resistance. When
the drop across the switch is small compared to V IN , the
simple lossless equation
()
I L t = IN t
lost as heat in the windings. Look for DCR values in the
inductors’ specification tables; values under 0.5 ? will give
best efficiency. An additional consideration is Electro-
Magnetic Interference (EMI). Toroid and pot core type
V
L
( 04 )
inductors are recommended in applications where EMI
must be kept to a minimum; for example, where there are
sensitive analog circuitry or transducers nearby. Rod core
types are a less expensive choice where EMI is not a
problem.
Specifying a proper inductor for an application requires
first establishing minimum and maximum input voltage,
can be used. These equations assume that at t = 0,
inductor current is zero. This situation is called “discon-
tinuous mode operation” in switching regulator parlance.
Setting “t” to the switch-ON time from the LT1109 speci-
fication table (typically 4.2 μ s) will yield I PEAK for a specific
“L” and V IN . Once I PEAK is known, energy in the inductor
at the end of the switch-ON time can be calculated as
LI PEAK
output voltage, and output current. In a step-up converter,
the inductive events add to the input voltage to produce the
output voltage. Power required from the inductor is deter-
E L =
1
2
2
( 05 )
mined by
E L must be greater than P L /F OSC for the converter to deliver
P L = (V OUT + V D – V IN ) (I OUT )
(01)
the required power. For best efficiency I PEAK should be
5
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| LT1109CS8-5 | 功能描述:IC REG BOOST 5V 0.1A 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LT1109CS8-5#PBF | 功能描述:IC REG BOOST 5V 0.1A 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LT1109CS8-5#TR | 功能描述:IC REG BOOST 5V 0.1A 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LT1109CS8-5#TRPBF | 功能描述:IC REG BOOST 5V 0.1A 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:20 系列:SIMPLE SWITCHER® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:12V 输入电压:4 V ~ 60 V PWM 型:电压模式 频率 - 开关:52kHz 电流 - 输出:1A 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 包装:管件 供应商设备封装:16-DIP 其它名称:*LM2575HVN-12LM2575HVN-12 |
| LT1109CZ-12 | 功能描述:IC REG BOOST 12V 0.1A TO92-3 RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:500 系列:- 类型:切换式电容器（充电泵），反相 输出类型:固定 输出数:1 输出电压:-3V 输入电压:2.3 V ~ 5.5 V PWM 型:Burst Mode? 频率 - 开关:900kHz 电流 - 输出:100mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 细型，TSOT-23-6 包装:带卷 (TR) 供应商设备封装:TSOT-23-6 其它名称:LTC1983ES6-3#TRMTR |
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