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| 型号： | LTC1473IGN#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/16页 |
| 文件大小： | 0K |
| 描述： | IC SWITCH DVR PWRPATH DUAL16SSOP |
| 标准包装： | 2,500 |
| 系列： | PowerPath™ |
| 应用： | 手持/移动设备 |
| FET 型： | N 沟道 |
| 输出数： | 2 |
| 内部开关： | 无 |
| 延迟时间 - 开启： | 22µs |
| 延迟时间 - 关闭： | 1µs |
| 电源电压： | 4.75 V ~ 30 V |
| 电流 - 电源： | 100µA |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SSOP |
| 包装： | 带卷 (TR) |
LTC1473
APPLICATIO N S I N FOR M ATIO N
As a general rule, select the switch with the lowest R DS(ON)
and able to withstand the maximum allowable V DS . This
will minimize the heat dissipated in the switches while
increasing the overall system efficiency. Higher switch
resistances can be tolerated in some systems with lower
current requirements, but care should be taken to ensure
that the power dissipated in the switches is never allowed
to rise above the manufacturers’ recommended level.
Inrush Current Sense Resistor, R SENSE
A small valued sense resistor (current shunt) is used by
the two switch pair drivers to measure and limit the inrush
or short-circuit current flowing through the conducting
switch pair.
The inrush current limit should be set at approximately 2 ×
or 3 × the maximum required output current. For example,
if the maximum current required by the DC/DC converter
is 2A, an inrush current limit of 6A is set by selecting a
0.033 ? sense resistor, R SENSE , using the following for-
mula:
R SENSE = (200mV)/I INRUSH
Note that the voltage drop across the resistor in this
example is only 66mV under normal operating conditions.
Therefore, the power dissipated in the resistor is ex-
tremely small (132mW), and a small 1/4W surface mount
resistor can be used in this application (the resistor will
The fault time delay is programmed with an external
capacitor between the TIMER pin and GND. At the instant
the MOSFET switch enters current limit, a 5.5 μ A current
source starts charging C TIMER through the TIMER pin.
When the voltage across C TIMER reaches 1.2V an internal
latch is set and the MOSFET switch is turned off. To reset
the latch, the logic input of the MOSFET gate driver is
deselected.
The fault time delay should be programmed as large as
possible, at least 3 × to 5 × the maximum switching transi-
tion period, to avoid prematurely tripping the protection
circuit. Conversely, for the protection circuit to be effec-
tive, the fault time delay must be within the safe operating
area of the MOSFET switches, as stated in the
manufacturer’s data sheet.
The maximum switching transition period happens during
a cold start, when a fully charged battery is connected to
an unpowered system. The inrush current charging the
system supply capacitor to the battery voltage determines
the switching transition period.
The following example illustrates the calculation of C TIMER.
Assume the maximum battery voltage is 20V, the system
supply capacitor is 68 μ F, the inrush current limit is 6A and
the maximum current required by the DC/DC converter is
2A. Then, the maximum switching transition period is
calculated using the following formula:
tolerate the higher power dissipation during current limit
for the duration of the fault time-out). A number of small
valued surface mount resistors are available that have
t SW(MAX) =
(V BAT(MAX) )(C IN(DC/DC) )
I INRUSH – I LOAD
been specifically designed for high efficiency current
sensing applications.
t SW(MAX) =
(20)(68 μ F)
6A – 2A
= 340 μ s
Programmable Fault Timer Capacitor, C TIMER
A fault timer capacitor, C TIMER , is used to program the time
duration the MOSFET switches are allowed to be in con-
tinuous current limit.
In the event of a fault condition, the MOSFET switch is
Multiplying 3 by 340 μ s gives 1.02ms, the minimum fault
delay time. Make sure this delay time does not fall outside
of the safe operating area of the MOSFET switch dissipat-
ing 60W (6A ? 20V/2). Using this delay time the C TIMER can
be calculated using the following formula:
) )
driven into current limit by the inrush current limit loop.
The MOSFET switch operating in current limit is in a high
dissipation mode and can fail catastrophically if not
promptly terminated.
C TIMER = 1.02ms
5.5 μ A
1.20V
= 4700pF
Therefore, C TIMER should be 4700pF.
10
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| LTC1473LCGN | 功能描述:IC SWITCH DVR PWRPATH DUAL16SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - O 圈控制器 系列:PowerPath™ 标准包装:1,000 系列:- 应用:电池备份，工业/汽车，大电流开关 FET 型:- 输出数:5 内部开关:是 延迟时间 - 开启:100ns 延迟时间 - 关闭:- 电源电压:3 V ~ 5.5 V 电流 - 电源:250µA 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC N 包装:带卷 (TR) |
| LTC1473LCGN#PBF | 功能描述:IC SWITCH DVR PWRPATH DUAL16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - O 圈控制器 系列:PowerPath™ 标准包装:1,000 系列:- 应用:电池备份，工业/汽车，大电流开关 FET 型:- 输出数:5 内部开关:是 延迟时间 - 开启:100ns 延迟时间 - 关闭:- 电源电压:3 V ~ 5.5 V 电流 - 电源:250µA 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC N 包装:带卷 (TR) |
| LTC1473LCGN#TR | 功能描述:IC DRIVER SWITCH DUAL LV 16SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - O 圈控制器 系列:PowerPath™ 标准包装:1,000 系列:- 应用:电池备份，工业/汽车，大电流开关 FET 型:- 输出数:5 内部开关:是 延迟时间 - 开启:100ns 延迟时间 - 关闭:- 电源电压:3 V ~ 5.5 V 电流 - 电源:250µA 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC N 包装:带卷 (TR) |
| LTC1473LCGN#TRPBF | 功能描述:IC SWITCH DVR PWRPATH DUAL16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - O 圈控制器 系列:PowerPath™ 标准包装:1,000 系列:- 应用:电池备份，工业/汽车，大电流开关 FET 型:- 输出数:5 内部开关:是 延迟时间 - 开启:100ns 延迟时间 - 关闭:- 电源电压:3 V ~ 5.5 V 电流 - 电源:250µA 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC N 包装:带卷 (TR) |
| LTC1474CMS8 | 功能描述:IC REG BUCK ADJ 0.75A 8MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
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