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参数资料
| 型号： | LTC3835EFE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/30页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 20TSSOP |
| 标准包装： | 74 |
| PWM 型： | 电流模式，混合 |
| 输出数： | 1 |
| 频率 - 最大： | 580kHz |
| 占空比： | 99.4% |
| 电源电压： | 4 V ~ 36 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： | 20-TSSOP（0.173"，4.40mm 宽）裸露焊盘 |
| 包装： | 管件 |
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LTC3835
APPLICATIONS INFORMATION
(
) (
)
I MAX 1/ 2
C IN Required I RMS ≈ ? V V IN – V OUT ?
? ?
V
8fC OUT ?
V OUT = 0.8V ? ? 1+ ?
C IN andC OUT Selection
In continuous mode, the source current of the top MOSFET
is a square wave of duty cycle (V OUT )/(V IN ). To prevent
large voltage transients, a low ESR capacitor sized for the
maximum RMS current must be used. The maximum RMS
capacitor current is given by:
OUT
IN
This formula has a maximum at V IN = 2V OUT , where I RMS
= I OUT /2. This simple worst-case condition is commonly
used for design because even significant deviations do not
offer much relief. Note that capacitor manufacturers’ ripple
current ratings are often based on only 2000 hours of life.
This makes it advisable to further derate the capacitor, or
to choose a capacitor rated at a higher temperature than
required. Several capacitors may be paralleled to meet
size or height requirements in the design. Due to the high
operating frequency of the LTC3835, ceramic capacitors
can also be used for CIN. Always consult the manufacturer
if there is any question.
The selection of C OUT is driven by the effective series
resistance (ESR). Typically, once the ESR requirement
is satisfied, the capacitance is adequate for filtering. The
output ripple (?V OUT ) is approximated by:
? 1 ?
? V OUT ≈ I RIPPLE ? ESR + ?
?
where f is the operating frequency, C OUT is the output
capacitance and I RIPPLE is the ripple current in the induc-
tor. The output ripple is highest at maximum input voltage
since I RIPPLE increases with input voltage.
Setting Output Voltage
The LTC3835 output voltage is set by an external feed-
back resistor divider carefully placed across the output,
as shown in Figure 1. The regulated output voltage is
determined by:
? R B ?
? R A ?
To improve the frequency response, a feed-forward ca-
pacitor, C FF , may be used. Great care should be taken to
route the V FB line away from noise sources, such as the
inductor and the SW line.
V OUT
LTC3835 R B C FF
V FB
R A
3835 F01
Figure 1. Setting Output Voltage
200
100
0
–100
–200
–300
–400
–500
–600
–700
0 1 2 3 4 5 6 7 8 9 10
V SENSE COMMON MODE VOLTAGE (V)
3835 F02
Figure 2. SENSE Pins Input Bias Current
vs Common Mode Voltage
SENSE + and SENSE – Pins
The common mode input range of the current comparator
is from 0V to 10V. Continuous linear operation is provided
throughout this range allowing output voltages from 0.8V
to 10V. The input stage of the current comparator requires
that current either be sourced or sunk from the SENSE pins
depending on the output voltage, as shown in the curve in
Figure 2. If the output voltage is below 1.5V, current will
flow out of both SENSE pins to the main output. In these
cases, the output can be easily pre-loaded by the V OUT
resistor divider to compensate for the current comparator’s
negative input bias current. Since V FB is servoed to the
0.8V reference voltage, R A in Figure 1 should be chosen
to be less than 0.8V/I SENSE , with I SENSE determined from
Figure 2 at the specified output voltage.
3835fd
15
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相关代理商/技术参数 |
参数描述 |
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| LTC3835EGN-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP 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 |
| LTC3835EGN-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 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) |
| LTC3835EUFD#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 20-QFN 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) |
| LTC3835EUFD#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 20-QFN 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) |
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