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參數(shù)資料
| 型號： | LTC1709-8 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | CHOKE COIL 2.7UH 950MA SMD |
| 中文描述： | 2相，5位VID，電流模式，高效率同步降壓型開關(guān)穩(wěn)壓器 |
| 文件頁數(shù)： | 23/28頁 |
| 文件大小： | 319K |
| 代理商： | LTC1709-8 |
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23
LTC1709-7
(from 0.2 to 5 times their suggested values) to optimize
transient response once the final PC layout is done and the
particular output capacitor type and value have been
determined. The output capacitors need to be decided
upon first because the various types and values determine
the loop gain and phase. An output current pulse of 20%
to 80% of full-load current having a rise time of <2
μ
s will
produce output voltage and I
TH
pin waveforms that will
give a sense of the overall loop stability without breaking
the feedback loop. The initial output voltage step resulting
from the step change in output current may not be within
the bandwidth of the feedback loop, so this signal cannot
be used to determine phase margin. This is why it is
better to look at the Ith pin signal which is in the feedback
loop and is the filtered and compensated control loop
response. The gain of the loop will be increased by
increasing R
C
and the bandwidth of the loop will be
increased by decreasing C
C
. If R
C
is increased by the
same factor that C
C
is decreased, the zero frequency will
be kept the same, thereby keeping the phase the same in
the most critical frequency range of the feedback loop.
The output voltage settling behavior is related to the
stability of the closed-loop system and will demonstrate
the actual overall supply performance.
Automotive Considerations: Plugging into the
Cigarette Lighter
As battery-powered devices go mobile, there is a natural
interest in plugging into the cigarette lighter in order to
conserve or even recharge battery packs during opera-
tion. But before you connect, be advised: you are plugging
into the supply from hell. The main battery line in an
automobile is the source of a number of nasty potential
transients, including load-dump, reverse-battery, and
double-battery.
Load-dump is the result of a loose battery cable. When the
cable breaks connection, the field collapse in the alternator
can cause a positive spike as high as 60V which takes
several hundred milliseconds to decay. Reverse-battery is
just what it says, while double-battery is a consequence of
tow truck operators finding that a 24V jump start cranks
cold engines faster than 12V.
The network shown in Figure 9 is the most straightfor-
ward approach to protect a DC/DC converter from the
ravages of an automotive power line. The series diode
prevents current from flowing during reverse-battery,
while the transient suppressor clamps the input voltage
during load-dump. Note that the transient suppressor
should not conduct during double-battery operation, but
must still clamp the input voltage below breakdown of the
converter. Although the LT1709-7 has a maximum input
voltage of 36V, most applications will be limited to 30V by
the MOSFET BV
DSS
.
APPLICATIU
W
U
U
Figure 9. Automotive Application Protection
V
IN
17097 F09
12V
50A I
PK
RATING
TRANSIENT VOLTAGE
SUPPRESSOR
GENERAL INSTRUMENT
1.5KA24A
LTC1709-7
Design Example
As a design example, assume V
IN
= 5V (nominal), V
IN
=5.5V
(max), V
OUT
= 1.8V, I
MAX
= 20A, T
A
= 70
°
C and f=300kHz.
The inductance value is chosen first based on a 30% ripple
current assumption. The highest value of ripple current
occurs at the maximum input voltage. Tie the FREQSET pin
to the INTV
CC
pin for 300kHz operation. The minimum
inductance for 30% ripple current is:
L
V
f
L
V
V
V
kHz
H
μ
A
V
V
OUT
(
OUT
IN
≥
)
≥
(
≥
)(
)(
)
1
1 8
.
300
1 35
.
30
10
1
1 8
5 5
.
%
.
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| LTC1709EG#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 36-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC1709EG#TR | 功能描述:IC REG CTRLR BUCK PWM CM 36-SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
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| LTC1709EG7 | 制造商:Linear Technology 功能描述: |
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