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参数资料
| 型号： | LTC3832-1ES8#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 8-SOIC |
| 标准包装： | 2,500 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 360kHz |
| 占空比： | 95% |
| 电源电压： | 3 V ~ 8 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： | -40°C ~ 85°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
LTC3832/LTC3832-1
APPLICATIO S I FOR ATIO
remains at a reduced voltage until the overload is re-
moved. Serious overloads generate a large overdrive at
CC, allowing it to pull SS down quickly and preventing
damage to the output components. By using the R DS(ON)
of Q1 to measure the output current, the current limiting
circuit eliminates an expensive discrete sense resistor that
would otherwise be required. This helps minimize the
number of components in the high current path.
The current limit threshold can be set by connecting an
external resistor R IMAX from the I MAX pin to the main V IN
supply at the drain of Q1. The value of R IMAX is determined
by:
R IMAX = (I LMAX )(R DS(ON)Q1 )/I IMAX
where:
I LMAX = I LOAD + (I RIPPLE /2)
I LOAD = Maximum load current
meant to prevent damage to the power supply circuitry
during fault conditions. The exact current level where the
limiting circuit begins to take effect will vary from unit to
unit as the R DS(ON) of Q1 varies. Typically, R DS(ON) varies
as much as ± 40%, and with ± 33% variation on the
LTC3832’s I MAX current, this can give a ± 73% variation on
the current limit threshold.
The R DS(ON) is high if the V GS applied to the MOSFET is
low. This occurs during power up when PV CC1 is ramping
up. To prevent the high R DS(ON) from activating the current
limit, the LTC3832 will disable the current limit circuit if
PV CC1 is less than 2.5V above V CC . To ensure proper
operation of the current limit circuit, PV CC1 must be at
least 2.5V above V CC when G1 is high. PV CC1 can go low
when G1 is low, allowing the use of the external charge
pump to power PV CC1 .
V IN
( V IN – V OUT )( V OUT )
( f OSC ) ( L O IN )
)( V
I RIPPLE = Inductor ripple current
=
f OSC = LTC3832 oscillator frequency = 300kHz
L O = Inductor value
LTC3832
CC
+
–
12 μ A
R IMAX
12
I MAX
I FB
13
1k
G1
G2
0.1 μ F
Q1
Q2
L O
+
+
C IN
V OUT
C OUT
3832 F04
R DS(ON)Q1 = On-resistance of Q1 at I LMAX
I IMAX = Internal 12 μ A sink current at I MAX
The R DS(ON) of Q1 usually increases with temperature. To
keep the current limit threshold constant, the internal
12 μ A sink current at I MAX is designed with a positive
temperature coefficient to provide first order correction
for the temperature coefficient of R DS(ON)Q1 .
In order for the current limit circuit to operate properly and
to obtain a reasonably accurate current limit threshold, the
I IMAX and I FB pins must be Kelvin sensed at Q1’s drain and
source pins. In addition, connect a 0.1 μ F decoupling
Figure 4. Current Limit Setting
Oscillator Frequency
The LTC3832 includes an onboard current controlled
oscillator that typically free-runs at 300kHz. The oscillator
frequency can be adjusted by forcing current into or out of
the FREQSET pin. With the pin floating, the oscillator runs
at about 300kHz. Every additional 1 μ A of current into/out
of the FREQSET pin decreases/increases the frequency by
10kHz. The pin is internally servoed to 1.265V. The
frequency can be estimated as:
1 . 265 V – V EXT 10 kHz
1 μ A
capacitor across R IMAX to filter switching noise. Other-
wise, noise spikes or ringing at Q1’s source can cause the
actual maximum current to be greater than the desired
f = 300 kHz +
R FSET
?
current limit set point. Due to switching noise and varia-
tion of R DS(ON) , the actual current limit trip point is not
highly accurate. The current limiting circuitry is primarily
where R FSET is a frequency programming resistor con-
nected between FREQSET and the external voltage source
V EXT .
sn3832 3832fs
10
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相关代理商/技术参数 |
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| LTC3832EGN | 功能描述:IC REG CTRLR BUCK PWM VM 16-SSOP 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) |
| LTC3832EGN#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 16-SSOP RoHS:是 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) |
| LTC3832EGN#TR | 功能描述:IC REG CTRLR BUCK PWM VM 16-SSOP 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) |
| LTC3832EGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 16-SSOP RoHS:是 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) |
| LTC3832EG-T | 制造商:LINEAR TECHNOLOGY CORPORA 功能描述: 制造商:LINTEC 功能描述: |
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