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参数资料
| 型号： | LT1680 |
| 厂商： | Linear Technology Corporation |
| 英文描述： | High Power DC/DC Step-Up Controller(大功率，DC/DC步升转换器) |
| 中文描述： | 高功率DC / DC升压控制器（大功率，直流/直流步升转换器） |
| 文件页数： | 13/16页 |
| 文件大小： | 272K |
| 代理商： | LT1680 |
13
LT1680
APPLICATIO
S I
FOR
ATIO
U
W
U
U
This feature is implemented by referencing this pin via a
resistor divider from the 5V
REF
pin to ground. The addi-
tional slope compensation will be affected at the point in
the oscillator waveform (at pin C
T
) corresponding to the
voltage set by the resistor divider. Additional slope com-
pensation can be calculated using the relation:
(
(
S
f
R
R
X
O
TH
SENSE
=
)( )
)(
)
2500
Amp/s
where R
TH
is the Thevenin resistance of the resistor
divider. Actual compensation will actually be somewhat
greater due to internal curvature correction circuitry that
imposes an exponential increase in the slope compensa-
tion waveform, further increasing the effective compensa-
tion slope up to 20% for a given setting.
Design example:
V
IN
= 20V
V
OUT
= 80V (DC = 0.75)
R
SENSE
= 0.01
f
O
= 100kHz
L = 20
μ
H
The minimum inductor usable with no additional slope
compensation is:
L
V
H
MIN
≥
(
.
)
(
)(
)
(
)
=
μ
20
0 01
.
1. –
– .
0 084 100000 1 0 75
47 6
.
Since L = 20
μ
H is less than L
MIN
, additional slope
compensation is necessary. The total slope compensa-
tion required is:
S
V
H
– .
X
≥
μ
1 0 75
(
)
=
20
20
1 5 1
. –
6
2 10
)
Amp/s
Subtracting the internally generated slope compensation
and solving for the required effective resistance at SL/ADJ
yields:
(
( )
R
f
R
f
k
EQ
O
SENSE
O
≤
)( )
) (
(
)( )
=
2500
2 10
0 084
.
21 5
6
–
.
S =0.084
f
R
O
SENSE
Amp/s
where f
O
is oscillator frequency and R
SENSE
is the external
current sense resistor. This yields a minimum inductance
requirement of:
L
V
[
R
DC
DC
f
MIN
IN
(
0 084
.
SENSE
)( )
O
≥
(
)(
)(
(
1
)
)
]
2
1
–
A down side of slope compensation is that, since the IC
servo loop senses an increase in perceived inductor cur-
rent, the internal current limit functions are affected such
that the maximum current capability of a regulator is
reduced by the same amount as the effective current
referred slope compensation. The LT1680, however, uses
a current limit scheme that is independent of the slope
compensation effects (Average Current Limiting). This
provides operation at any duty cycle with no reduction in
current sourcing capability, provided ripple current peak
amplitude is less than 15% of the current limit value. For
example, if the converter is set up to average current limit
at 10A, as long as the peak inductor current is less than
11.5A, duty cycles up to 90% can be achieved without
compromising the average current limit value.
If an inductor smaller than the minimum required for
internal slope compensation (calculated above as L
MIN
) is
desired, additional slope compensation is necessary. The
LT1680 provides this capability through the SL/ADJ pin.
Figure 10. Maximum Peak Ripple Current (Normalized)
vs Duty Cycle for Average Current Limit
DUTY CYCLE
0
1.10
M
P
/
A
)
1.15
1.25
1.30
1.35
0.2 0.3 0.4 0.5 0.6 0.7 0.8
1680 F10
1.20
0.1
0.9
1.40
1.45
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1680C | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Power DC/DC Step-Up Controller |
| LT1680CN | 功能描述:IC REG CTRLR BST PWM CM 16-DIP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LT1680CN#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-DIP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LT1680CSW | 功能描述:IC REG CTRLR BST PWM CM 16-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LT1680CSW#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
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