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參數資料
| 型號： | LT1308B |
| 廠商： | Linear Technology Corporation |
| 英文描述： | High Current, Micropower Single Cell, 600kHz DC/DC Converters |
| 中文描述： | 大電流，微功耗單細胞，600kHz的直流/直流轉換器 |
| 文件頁數： | 7/12頁 |
| 文件大?。?/td> | 185K |
| 代理商： | LT1308B |
7
LT1308A/LT1308B
APPLICATIO
S I
FOR
ATIO
U
LAYOUT HINTS
W
U
U
The LT1308A/LT1308B switch current at high speed, man-
dating careful attention to layout for proper performance.
You will not get advertised performance with careless
layouts Figure 4 shows recommended component place-
ment for a boost (step-up) converter. Follow this closely in
your PC layout. Note the direct path of the switching loops.
Input capacitor C1 mustbe placed close (<5mm) to the IC
package. As little as 10mm of wire or PC trace from C
IN
to
V
IN
will cause problems such as inability to regulate or
oscillation.
The negative terminal of output capacitor C2 should tie
close to Pin 4 of the LT1308A/LT1308B. Doing this
reduces dI/dt in the ground copper which keeps high
frequency spikes to a minimum. The DC/DC converter
ground should tie to the PC board ground plane at one
place only, to avoid introducing dI/dt in the ground plane.
A SEPIC (Single-Ended Primary Inductance Converter)
schematic is shown in Figure 5. This converter topology
produces a regulated output over an input voltage range
that spans (i.e., can be higher or lower than) the output.
Recommended component placement for a SEPIC is
shown in Figure 6.
COMPONENT SELECTION
Inductors
Suitable inductors for use with the LT1308A/LT1308B
must fulfill two requirements. First, the inductor must be
able to handle current of 2A steady-state, as well as
support transient and start-up current over 3A without
inductance decreasing by more than 50% to 60%. Second,
the DCR of the inductor should have low DCR, under 0.05
so that copper loss is minimized. Acceptable inductance
values range between 2
μ
H and 20
μ
H, with 4.7
μ
H best for
most applications. Lower value inductors are physically
smaller than higher value inductors for the same current
capability.
Table 1 lists some inductors we have found to perform well
in LT1308A/LT1308B application circuits. This is not an
exclusive list.
Table 1
VENDOR
PART NO.
VALUE
PHONE NO.
Murata
LQH6C4R7
4.7
μ
H
770-436-1300
Sumida
CDRH734R7
4.7
μ
H
847-956-0666
Coiltronics
CTX5-1
5
μ
H
561-241-7876
Capacitors
Equivalent Series Resistance (ESR) is the main issue
regarding selection of capacitors, especially the output
capacitors.
The output capacitors specified for use with the LT1308A/
LT1308B circuits have low ESR and are specifically
designed for power supply applications. Output voltage
ripple of a boost converter is equal to ESR multiplied by
switch current. The performance of the AVX TPSD227M006
220
μ
F tantalum can be evaluated by referring to Figure 4.
When the load is 800mA, the peak switch current is
approximately 2A. Output voltage ripple is about 60mV
P-
P
, so the ESR of the output capacitor is 60mV/2A or 0.03
.
Ripple can be further reduced by paralleling ceramic units.
Table 2 lists some capacitors we have found to perform
well in the LT1308A/LT1308B application circuits. This is
not an exclusive list.
Table 2
VENDOR
SERIES
PART NO.
VALUE
PHONE NO.
AVX
TPS
TPSD227M006
220
μ
F, 6V
803-448-9411
AVX
TPS
TPSD107M010
100
μ
F, 10V
803-448-9411
Taiyo Yuden
X5R
LMK432BJ226
22
μ
F, 10V
408-573-4150
Taiyo Yuden
X5R
TMK432BJ106
10
μ
F, 25V
408-573-4150
Diodes
We have found Motorola MBRS130 and International
Rectifier 10BQ015 to perform well. For applications where
V
OUT
exceeds 30V, use 40V diodes such as MBRS140 or
10BQ040.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LT1308BCF | 功能描述:IC REG BOOST 5V 1A 14TSSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:20 系列:SIMPLE SWITCHER® 類型:降壓（降壓） 輸出類型:固定 輸出數:1 輸出電壓:12V 輸入電壓:4 V ~ 60 V PWM 型:電壓模式 頻率 - 開關:52kHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:16-DIP（0.300"，7.62mm） 包裝:管件 供應商設備封裝:16-DIP 其它名稱:*LM2575HVN-12LM2575HVN-12 |
| LT1308BCF#PBF | 功能描述:IC REG BOOST 5V 1A 14TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:20 系列:SIMPLE SWITCHER® 類型:降壓（降壓） 輸出類型:固定 輸出數:1 輸出電壓:12V 輸入電壓:4 V ~ 60 V PWM 型:電壓模式 頻率 - 開關:52kHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:16-DIP（0.300"，7.62mm） 包裝:管件 供應商設備封裝:16-DIP 其它名稱:*LM2575HVN-12LM2575HVN-12 |
| LT1308BCF#TR | 功能描述:IC REG BOOST 5V 1A 14TSSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:20 系列:SIMPLE SWITCHER® 類型:降壓（降壓） 輸出類型:固定 輸出數:1 輸出電壓:12V 輸入電壓:4 V ~ 60 V PWM 型:電壓模式 頻率 - 開關:52kHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:16-DIP（0.300"，7.62mm） 包裝:管件 供應商設備封裝:16-DIP 其它名稱:*LM2575HVN-12LM2575HVN-12 |
| LT1308BCF#TRPBF | 功能描述:IC REG BOOST 5V 1A 14TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:20 系列:SIMPLE SWITCHER® 類型:降壓（降壓） 輸出類型:固定 輸出數:1 輸出電壓:12V 輸入電壓:4 V ~ 60 V PWM 型:電壓模式 頻率 - 開關:52kHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:16-DIP（0.300"，7.62mm） 包裝:管件 供應商設備封裝:16-DIP 其它名稱:*LM2575HVN-12LM2575HVN-12 |
| LT1308BCF-PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Current, Micropower Single Cell, 600kHz DC/DC Converters |
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