參數(shù)資料
型號(hào)： LT1339
廠商： Linear Technology Corporation
英文描述： High Efficiency, Synchronous, 4-Switch Buck-Boost Controller
中文描述： 高效率，同步，四開(kāi)關(guān)降壓升壓控制器
文件頁(yè)數(shù)： 13/20頁(yè)
文件大?。?/td> 415K
代理商： LT1339
13
LT1339
APPLICATIO
S I
N
FOR
ATIO
U
W
U
For duty cycles less than 50% (DC < 0.5), S
X
is negative
and is not required. For duty cycles greater than 50%, S
X
takes on values dependent on S1 and duty cycle. This leads
to a minimum inductance requirement for a given V
IN
and
duty cycle of:
(
L
V
S
DC
MIN
IN
X
=
)
2
1
The LT1339 contains an internal S
X
slope compensation
ramp that has an equivalent current referred value of:
0.084
f
R
O
SENSE
Amp/s
where f
O
is oscillator frequency. This yields a minimum
inductance requirement of:
≥
( )(
(
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 LT1339, however, uses
a current limit scheme that is independent of slope com-
pensation effects (average current limit). This provides
operation at any duty cycle with no reduction in current
sourcing capability, provided ripple current peak ampli-
tude is less than 15% of the current limit value. For
example, if the supply is set up to 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.
L
V
R
DC
2
f
MIN
IN
SENSE
0 084
O
)
(
)
)( )
1
If an inductor smaller than the minimum required for
internal slope compensation (calculated above as L
MIN
) is
desired, additional slope compensation is required. The
LT1339 provides this capability through the SL/ADJ pin.
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 CT) corresponding to the
voltage set by the resistor divider. Additional slope com-
pensation can be calculated using the relation:
(
(
where R
EQ
is the effective resistance of the resistor divider.
Actual compensation will be somewhat greater due to
internal curvature correction circuitry that imposes an
exponential increase in the slope compensation wave-
form, further increasing the effective compensation slope
up to 20% for a given setting.
S
f
R
R
XADD
O
EQ
SENSE
=
)( )
)(
)
2500
Amp/s
OSCILLATOR
PERIOD
TIME
0
0
a
b
I
T1
I
2
I
1
S1
S1
S2
S2
S1 + S
X
1339 F05
Figure 5. Inductor Current at DC > 50% and
Slope Compensation Adjusted Signal
DUTY CYCLE (DC)
0
P
A
0.4
1.45
1.40
1.35
1.30
1.25
1.20
1.15
1.10
LT1339 F06
0.2
0.6
0.1
0.5
0.3
0.7 0.8 0.9
Figure 6. Maximum Ripple Current (Normalized)
vs Duty Cycle for Average Current Limit
Design Example:
V
IN
= 20V
V
OUT
= 15V (DC = 0.75)
R
SENSE
= 0.01
f
O
= 100kHz
L = 5
μ
H
The minimum inductor usable with no additional slope
compensation is:
相關(guān)PDF資料
PDF描述
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LT1339CSW Octal Buffers/Drivers With 3-State Outputs 20-SOIC 0 to 70
LT1339I Octal Buffers/Drivers With 3-State Outputs 20-SOIC 0 to 70
LT1339IN Octal Buffers/Drivers With 3-State Outputs 20-PDIP 0 to 70
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LT1339C 制造商:LINER 制造商全稱(chēng):Linear Technology 功能描述:High Power Synchronous DC/DC Controller
LT1339CN 功能描述:IC REG CTRLR BST PWM CM 20-DIP RoHS:否 類(lèi)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(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤(pán) 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱(chēng):LM1771SSDX
LT1339CN#PBF 功能描述:IC REG CTRLR BST PWM CM 20-DIP RoHS:是 類(lèi)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:2,000 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:50% 電源電壓:9 V ~ 10 V 降壓:無(wú) 升壓:是 回掃:是 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 85°C 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 包裝:帶卷 (TR)
LT1339CN#PBF 制造商:Linear Technology 功能描述:DC-DC CONTROLLER CURRENT MODE 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, CURRENT MODE, 150KHZ,
LT1339CSW 功能描述:IC REG CTRLR BST PWM CM 20-SOIC RoHS:否 類(lèi)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(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤(pán) 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱(chēng):LM1771SSDX
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