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參數(shù)資料
| 型號： | LT1110-12 |
| 廠商： | Linear Technology Corporation |
| 元件分類： | DC/DC變換器 |
| 英文描述： | Micropower DC-DC Converter Adjustable and Fixed 5V, 12V |
| 中文描述： | 微功率DC - DC轉(zhuǎn)換可調(diào)和固定5V，12V的 |
| 文件頁數(shù)： | 12/16頁 |
| 文件大?。?/td> | 310K |
| 代理商： | LT1110-12 |
LT1110
12
U
S
A
O
PPLICATI
IU
U
Using the I
LIM
Pin
The LT1110 switch can be programmed to turn off at a set
switch current, a feature not found on competing devices.
This enables the input to vary over a wide range without
exceeding the maximum switch rating or saturating the
inductor. Consider the case where analysis shows the
LT1110 must operate at an 800mA peak switch current
with a 2.0V input. If V
IN
rises to 4V, peak current will rise
to 1.6A, exceeding the maximum switch current rating.
With the proper resistor selected (see the “Maximum
Switch
Current vs R
LIM
” characteristic), the switch current
will be limited to 800mA, even if the input voltage
increases.
Another situation where the I
LIM
feature is useful occurs
when the device goes into continuous mode operation.
This occurs in step-up mode when
V
V
V
V
DC
IN
SW
1
When the input and output voltages satisfy this relation-
ship, inductor current does not go to zero during the
switch OFF time. When the switch turns on again, the
current ramp starts from the non-zero current level in the
inductor just prior to switch turn on. As shown in Figure 9,
the inductor current increases to a high level before the
comparator turns off the oscillator. This high current can
cause excessive output ripple and requires oversizing the
output capacitor and inductor. With the I
LIM
feature,
however, the switch current turns off at a programmed
level as shown in Figure 10, keeping output ripple to a
minimum.
OUT
DIODE
+
<
1
25
(
.
)
Figure 11 details current limit circuitry. Sense transistor
Q1, whose base and emitter are paralleled with power
switch Q2, is ratioed such that approximately 0.5% of Q2’s
collector current flows in Q1’s collector. This current is
passed through internal 80
resistor R1 and out through
the I
LIM
pin. The value of the external resistor connected
between I
LIM
and V
IN
set the current limit. When sufficient
switch current flows to develop a V
BE
across R1 + R
LIM
, Q3
turns on and injects current into the oscillator, turning off
the switch. Delay through this circuitry is approximately
800ns. The current trip point becomes less accurate for
switch ON times less than 3
μ
s. Resistor values program-
ming switch ON time for 800ns or less will cause spurious
response in the switch circuitry although the device will
still maintain output regulation.
LT1110 TA05
I
OFF
L
ON
SWITCH
Figure 9. No Current Limit Causes Large Inductor
Current Build-Up
LT1110 TA06
I
ON
OFF
L
SWITCH
PROGRAMMED CURRENT LIMIT
Figure 10. Current Limit Keeps Inductor Current Under Control
LT1110 TA17
SW2
SW1
Q2
DRIVER
OSCILLATOR
V
IN
I
LIM
R1
80
(INTERNAL)
R
(EXTERNAL)
Q1
Q3
Figure 11. LT1110 Current Limit Circuitry
Using the Gain Block
The gain block (GB) on the LT1110 can be used as an error
amplifier, low battery detector or linear post regulator. The
gain block itself is a very simple PNP input op amp with an
open collector NPN output. The negative input of the gain
block is tied internally to the 220mV reference. The posi-
tive input comes out on the SET pin.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT1110-5 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Micropower DC-DC Converter Adjustable and Fixed 5V, 12V |
| LT1110CN8 | 功能描述:IC REG BUCK BOOST ADJ 0.4A 8DIP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
| LT1110CN8#PBF | 功能描述:IC REG BUCK BOOST ADJ 0.4A 8DIP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤 |
| LT1110CN8-12 | 功能描述:IC REG BUCK BOOST 12V 0.4A 8DIP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 產(chǎn)品培訓(xùn)模塊:MIC23xxx HyperLight Load™ Regulators 標(biāo)準(zhǔn)包裝:5,000 系列:HyperLight Load® 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.8V 輸入電壓:2.7 V ~ 5.5 V PWM 型:混合物 頻率 - 開關(guān):4MHz 電流 - 輸出:2A 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:8-VFDFN 裸露焊盤，8-MLF? 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-MLF?（2x2） 產(chǎn)品目錄頁面:1094 (CN2011-ZH PDF) 其它名稱:576-3303-2 |
| LT1110CN8-12#PBF | 功能描述:IC REG BUCK BOOST 12V 0.4A 8DIP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 產(chǎn)品培訓(xùn)模塊:MIC23xxx HyperLight Load™ Regulators 標(biāo)準(zhǔn)包裝:5,000 系列:HyperLight Load® 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.8V 輸入電壓:2.7 V ~ 5.5 V PWM 型:混合物 頻率 - 開關(guān):4MHz 電流 - 輸出:2A 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:8-VFDFN 裸露焊盤，8-MLF? 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-MLF?（2x2） 產(chǎn)品目錄頁面:1094 (CN2011-ZH PDF) 其它名稱:576-3303-2 |
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