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参数资料
| 型号： | LTC4217IFE#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO20 |
| 封装： | 4.40 MM, LEAD FREE, PLASTIC, SSOP-20 |
| 文件页数： | 5/18页 |
| 文件大小： | 238K |
| 代理商： | LTC4217IFE#PBF |
LTC4217
13
4217fe
applicaTions inForMaTion
12V Fixed Version
In the LTC4217-12 the UV, OV and FB pins are driven by
internal dividers which may need to be filtered to prevent
false faults. By placing a bypass capacitor on these pins
the faults are delayed by the RC time constant. Use the
RIN value from the electrical characteristics table for this
calculation.
In cases where the fixed thresholds need a slight adjust-
ment, placing a resistor from the UV or OV pins to VDD
or GND will adjust the threshold up or down. Likewise
placing a resistor between FB pin to OUT or GND adjusts
the threshold. Again use the RIN value from the electrical
characteristics table for this calculation.
An example in Figure 5 raises the UV turn-on voltage from
9.88V to 10.5V. Increasing the UV level requires adding a
resistorbetweenUVandground.Theresistor,RSHUNT1,can
be calculated using electrical table parameters as follows:
RSHUNT1=
R IN
( ) VOLD
VNEW – VOLD
(
)
=
18k 9.88
10.5 – 9.88
(
)
= 287k
In this same figure the OV threshold is lowered from
15.05V to 13.5V. Decreasing the OV threshold requires
adding a resistor between VDD and OV. This resistor can
be calculated as follows:
RSHUNT2 =
R IN
( ) VOLD
V TH
( )
VNEW – VOV TH
( )
(
)
VOLD – VNEW
(
)
=
18k 15.05
1.235
13.5 – 1.235
(
)
15.05 – 13.5
(
)
= 1.736M
Use the equation for RSHUNT1 for increasing the OV and
FB thresholds. Likewise use the equation for RSHUNT2 for
decreasing the UV and FB thresholds.
Design Example
Consider the following design example (Figure 6): VIN =
12V, IMAX = 2A. IINRUSH = 100mA, CL = 330F, VUVON =
9.88V,VOVOFF=15.05V,VPWRGD=10.5V.Acurrentlimitfault
triggers an automatic restart of the power-up sequence.
Figure 5. Adjusting LTC4217-12 Thresholds
4217 F05
LTC4217-12
RSHUNT1
RSHUNT2
VDD
OV
UV
Figure 6. 1.5A, 12V Card Resident Application
ADC
C1
0.1F
12V
VOUT
12V
1.5A
R2
20k
4217 F06
R1
10k
CL
330F
VDD
UV
OUT
PG
GND
IMON
LTC4217-12DHC
INTVCC
TIMER
FLT
12V
+
The inrush current is defined by the current required to
charge the output capacitor using the fixed 0.3V/ms GATE
charge-up rate. The inrush current is defined as:
IINRUSH =CL
0.3V
ms
=
330F
0.3V
ms
=
100mA
As mentioned previously the charge-up time is the out-
put voltage (12V) divided by the output rate of 0.3V/ms
resulting in 40ms. The peak power dissipation of 12V at
100mA (or 1.2W) is within the SOA of the pass MOSFET
for 40ms (see MOSFET SOA curve in the Typical Perfor-
mance Characteristics section).
NextthepowerdissipatedintheMOSFETduringovercurrent
must be limited. The active current limit uses a timer to
prevent excessive energy dissipation in the MOSFET. The
worst-case power dissipation occurs when the voltage
versus current profile of the foldback current limit is at
the maximum. This occurs when the current is 2A and the
voltage is one half of the 12V or 6V. See the Current Limit
Sense Voltage vs FB Voltage in the Typical Performance
Characteristics section to view this profile. In order to
survive 12W, the MOSFET SOA dictates a maximum time
of 10ms (see SOA graph). Use the internal 2ms timer
相关PDF资料 |
PDF描述 |
|---|---|
| LTC4217IDHC#TR | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO16 |
| LTC4217CDHC#TR | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO16 |
| LTC4217HFE#PBF | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO20 |
| LTC4217CDHC | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO16 |
| LTC4217CDHC-12#TRPBF | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO16 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4217IFE-TR | 制造商:LINER 制造商全称:Linear Technology 功能描述:2A Integrated Hot Swap Controller |
| LTC4217IFE-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:2A Integrated Hot Swap Controller |
| LTC4218 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Hot Swap Controller |
| LTC4218CDHC-12#PBF | 功能描述:IC CTLR HOT SWAP 16-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
| LTC4218CDHC-12#TRPBF | 功能描述:IC CNTRLR HOT SWAP 16-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
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