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參數(shù)資料
| 型號(hào)： | LT1308BIS8 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | High Current, Micropower Single Cell, 600kHz DC/DC Converters |
| 中文描述： | 4.5 A SWITCHING REGULATOR, 750 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 0.150 INCH, PLASTIC, SOP-8 |
| 文件頁數(shù)： | 9/12頁 |
| 文件大?。?/td> | 185K |
| 代理商： | LT1308BIS8 |
9
LT1308A/LT1308B
APPLICATIO
S I
FOR
ATIO
U
SHDN PIN
W
U
U
The LT1308A/LT1308B SHDN pin is improved over the
LT1308. The pin does not require tying to V
IN
to enable the
device, but needs only a logic level signal. The voltage on
the SHDN pin can vary from 1V to 10V independent of V
IN
.
Further, floating this pin has the same effect as grounding,
which is to shut the device down, reducing current drain
to 1
μ
A or less.
LOW-BATTERY DETECTOR
The low-battery detector on the LT1308A/LT1308B fea-
tures improved accuracy and drive capability compared to
the LT1308. The 200mV reference has an accuracy of
±
2%
and the open-collector output can sink 50
μ
A. The LT1308A/
LT1308B low-battery detector is a simple PNP input gain
stage with an open-collector NPN output. The negative
input of the gain stage is tied internally to a 200mV
reference. The positive input is the LBI pin. Arrangement
as a low-battery detector is straightforward. Figure 7
details hookup. R1 and R2 need only be low enough in
value so that the bias current of the LBI pin doesn’t cause
large errors. For R2, 100k is adequate. The 200mV refer-
ence can also be accessed as shown in Figure 8.
A cross plot of the low-battery detector is shown in
Figure 9. The LBI pin is swept with an input which varies
from 195mV to 205mV, and LBO with a 100k pull-up
resistor, is displayed.
START-UP
The LT1308A/LT1308B can start up into heavy loads,
unlike many CMOS DC/DC converters that derive operat-
ing voltage from the output (a technique known as
“bootstrapping”). Figure 10 details start-up waveforms of
Figure 1’s circuit with a 20
load and V
IN
of 1.5V. Inductor
current rises to 3.5A as the output capacitor is charged.
After the output reaches 5V, inductor current is about 1A.
In Figure 11, the load is 5
and input voltage is 3V. Output
voltage reaches 5V 500
μ
s after the device is enabled.
Figure 12 shows start-up behavior of Figure 5’s SEPIC
circuit, driven from a 9V input with a 10
load. The output
reaches 5V in about 1ms after the device is enabled.
GSM AND CDMA PHONES
The LT1308A/LT1308B are suitable for converting a single
Li-Ion cell to 5V for powering RF power stages in GSM or
CDMA phones. Improvements in the LT1308A/LT1308B
error amplifiers allow external compensation values to be
reduced, resulting in faster transient response compared
to the LT1308. The circuit of Figure 13 (same as Figure 1,
printed again for convenience) provides a 5V, 1A output
from a Li-Ion cell. Figure 14 details transient response at
the LT1308A operating at a V
IN
of 4.2V, 3.6V and 3V.
Ripple voltage in Burst Mode operation can be seen at
10mA load. Figure 15 shows transient response of the
LT1308B under the same conditions. Note the lack of
Burst Mode ripple at 10mA load.
Figure 7. Setting Low-Battery Detector Trip Point
Figure 8. Accessing 200mV Reference
LBO
LBI
TO PROCESSOR
R1
100k
R2
100k
V
IN
V
BAT
LT1308A
LT1308B
1308 F07
5V
GND
200mV
INTERNAL
REFERENCE
–
+
R1 =V
LB
– 200mV
2
μ
A
V
IN
V
BAT
LT1308A
LT1308B
LBI
LBO
200k
10
μ
F
GND
10k
1308 F08
2N3906
V
REF
200mV
+
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LT1308A | CAPACITOR 3900UF 35V ELECT TSUP |
| LT1308ACF | High Current, Micropower Single Cell, 600kHz DC/DC Converters |
| LT1308ACS8 | High Current, Micropower Single Cell, 600kHz DC/DC Converters |
| LT1308B | High Current, Micropower Single Cell, 600kHz DC/DC Converters |
| LT1308BCF | High Current, Micropower Single Cell, 600kHz DC/DC Converters |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT1308BIS8#PBF | 功能描述:IC REG BOOST 5V 1A 8SOIC 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:250 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 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LT1308BIS8#PBF | 制造商:Linear Technology 功能描述:DC-DC CONVERTER BOOST 600KHZ 3A SOIC 制造商:Linear Technology 功能描述:DC-DC CONVERTER, BOOST, 600KHZ, 3A, SOIC |
| LT1308BIS8#TR | 功能描述:IC REG BOOST 5V 1A 8SOIC 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 |
| LT1308BIS8#TRPBF | 功能描述:IC REG BOOST 5V 1A 8SOIC 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 |
| LT1308BIS8PBF | 制造商:Linear Technology 功能描述:DC-DC 1-Cell Micropower 1A 600kHz SOIC8 |
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