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参数资料
| 型号： | LTC3786EUD#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PQCC16 |
| 封装： | 3 X 3 MM, LEAD FREE, PLASTIC, MO-220WEED-2,QFN-16 |
| 文件页数： | 15/34页 |
| 文件大小： | 397K |
| 代理商： | LTC3786EUD#PBF |
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LTC3786
22
3786fa
applicaTions inForMaTion
The RSENSE resistor value can be calculated by using the
maximum current sense voltage specification with some
accommodation for tolerances:
RSENSE ≤
75mV
9.25A
= 0.008
Choosing 1% resistors: RA = 5k and RB = 95.3k yields an
output voltage of 24.072V.
ThepowerdissipationonthetopsideMOSFETineachchan-
nelcanbeeasilyestimated.ChoosingaVishaySi7848BDP
MOSFET results in: RDS(ON) = 0.012Ω, CMILLER = 150pF. At
maximum input voltage with T(estimated) = 50°C:
PMAIN =
24V – 12V
(
)24V
12V
(
)
2
4A
( )
2
1
+ 0.005
(
) 50°C – 25°C
(
)
0.008
+ 1.7
( ) 24V
(
)
3 4A
12V
150pF
(
) 350kHz
(
) = 0.7W
COUT is chosen to filter the square current in the output.
The maximum output current peak is:
IOUT(PEAK) =IOUT(MAX) 1+
RIPPLE%
2
= 4 1+
31%
2
= 4.62A
A low ESR (5mΩ) capacitor is suggested. This capacitor
will limit output voltage ripple to 23.1mV (assuming ESR
dominate ripple).
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of
the IC. These items are also illustrated graphically in the
layout diagram of Figure 6. Figure 7 illustrates the current
waveforms present in the various branches the synchro-
nous regulator operating in the continuous mode. Check
the following in your layout:
1. Put the bottom N-channel MOSFET MBOT and the top
N-channel MOSFET MTOP in one compact area with
COUT.
2. Are the signal and power grounds kept separate? The
combined IC signal ground pin and the ground return
of CINTVCC must return to the combined COUT (–)
terminals. The path formed by the bottom N-channel
MOSFET and the capacitor should have short leads and
PC trace lengths. The output capacitor (–) terminals
should be connected as close as possible to the (–)
source terminal of the bottom MOSFET.
3. Does the LTC3786 VFB pin’s resistive divider connect
to the (+) terminal of COUT? The resistive divider must
be connected between the (+) terminal of COUT and
signal ground and placed close to the VFB pin. The
feedback resistor connections should not be along the
high current input feeds from the input capacitor(s).
4. Are the SENSE– and SENSE+ leads routed together with
minimumPCtracespacing?Thefiltercapacitorbetween
SENSE+ and SENSE– should be as close as possible
to the IC. Ensure accurate current sensing with Kelvin
connections at the sense resistor.
5. Is the INTVCC decoupling capacitor connected close
to the IC, between the INTVCC and the power ground
pin? This capacitor carries the MOSFET drivers’ cur-
rent peaks. An additional 1F ceramic capacitor placed
immediately next to the INTVCC and GND pins can help
improve noise performance substantially.
6. Keep the switching node (SW), top gate node (TG) and
boost node (BOOST) away from sensitive small-signal
nodes. All of these nodes have very large and fast
moving signals and, therefore, should be kept on the
output side of the LTC3786 and occupy a minimal PC
trace area.
7. Use a modified “star ground” technique: a low imped-
ance, large copper area central grounding point on
the same side of the PC board as the input and output
capacitors with tie-ins for the bottom of the INTVCC
decouplingcapacitor,thebottomofthevoltagefeedback
resistive divider and the GND pin of the IC.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3786IMSE#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-MSOP 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) |
| LTC3786IMSE#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 16-MSOP 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) |
| LTC3786IUD#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-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) |
| LTC3786IUD#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 16-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) |
| LTC3787EGN#PBF | 功能描述:IC REG CTRLR BST PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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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