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参数资料
| 型号： | MAX894LESA+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 7/8页 |
| 文件大小： | 0K |
| 描述： | IC SW P-CH HS 8-SOIC |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 100 |
| 类型： | 高端开关 |
| 输出数： | 2 |
| Rds（开）： | 225 毫欧 |
| 内部开关： | 是 |
| 电流限制： | 500mA |
| 输入电压： | 2.7 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOIC |
| 包装： | 管件 |
Dual, Current-Limited, High-Side P-Channel
Switches with Thermal Shutdown
_______________Detailed Description
The MAX894L/MAX895L P-channel MOSFET power
switches limit output current to a user-programmed
level. When the output current is increased beyond the
SET
set current level, the current also increases through the
replica switch (I OUT /1050) (MAX895) and through R SET
(Figure 1). The current-limit error amplifier compares
the voltage across R SET to the internal 1.24V reference,
and regulates the current back to the lesser of the pro-
MAX894L
MAX895L
GND
R SET
grammed current limit (I LIMIT ) or the maximum current
limit (I MAX ).
These switches are not bidirectional; therefore, the
input voltage must be higher than the output voltage.
Setting the Current Limit
The MAX894L/MAX895L feature internal current-limiting
circuitry with maximum programmable values (I MAX ) of
500mA, and 250mA, respectively. For best perfor-
mance, set the current limit (I LIMIT ) between 0.2I MAX ≤
I LIMIT ≤ I MAX . This current limit remains in effect
throughout the input supply-voltage range.
Program the current limit with a resistor (R SET_ ) con-
nected from SET_ to ground (Figure 2) as follows:
I SET = I LIMIT / I RATIO
R SET = 1.24V / I SET = (1.24V x I RATIO ) / I LIMIT
where I LIMIT is the desired current limit for either switch
and I RATIO is the I OUT to I SET current ratio (1085A/A for
the MAX894L and 1050A/A for the MAX895L.
Short-Circuit Protection
The MAX894L/MAX895L are short-circuit-protected
switches. In the event of an output short circuit or cur-
rent-overload condition, the current through either switch
is limited by the internal current-limiting error amplifier to
1.5 x I LIMIT . When the fault condition is removed, the
replica error amplifier sets the current limit back to I LIMIT .
For a high ? V DS / ? t during an output short-circuit condi-
tion, the switch turns off and disconnects the input supply
from the output. The current-limiting amplifier then slowly
turns the switch on with the output current limited to
1.5 x I SET . When the fault condition is removed, the current
limit is set back to I LIMIT . Refer to Current-Limit Response
graphs in the Typical Operating Characteristics .
Thermal Shutdown
The MAX894L/MAX895L feature thermal shutdown. The
switch turns off when the junction temperature exceeds
+135°C. Once the device cools by 10°C, the switch turns
back on. If the fault short-circuit condition is not
removed, the switch cycles on and off, resulting in a
pulsed output.
Figure 2. Setting the Current Limit
__________Applications Information
Input Capacitor
To limit input voltage drop during momentary output
short-circuit conditions, place a capacitor from IN to
GND. A 1 μ F ceramic capacitor is adequate for most
applications; however, higher capacitor values further
reduce voltage drop at the input.
Output Capacitor
Connect a 0.1 μ F capacitor from OUT to GND. This
capacitor prevents inductive parasitics from pulling
OUT negative during turn-off.
Layout and Thermal-Dissipation
Consideration
To take full advantage of the switch-response time to
output short-circuit conditions, it is very important to
keep all traces as short as possible, reducing the effect
of undesirable parasitic inductance. Place input and
output capacitors as close as possible to the device
(no more than 5mm).
Under normal operating conditions, the package can
dissipate and channel heat away. Calculate the maxi-
mum power as follows:
P = I 2LIMITA x R ONA + I 2LIMITB x R ONB
where R ONA and R ONB are the on-resistances of
switches A and B, respectively.
When one or both outputs are short circuited, the volt-
age drop across the switch equals the input supply.
Hence, the power dissipated across the switch increas-
es, as does the die temperature. If the fault condition is
not removed, the thermal-overload-protection circuitry
turns the switch off until the die temperature falls by
10°C. A ground plane in contact with the device helps
to further dissipate heat.
_______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX894LESA+ | 功能描述:电源开关 IC - 配电 Current-Limited High-Side PCh Switch RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
| MAX894LESA+T | 功能描述:电源开关 IC - 配电 Current-Limited High-Side PCh Switch RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
| MAX894LESA-T | 功能描述:电源开关 IC - 配电 Current-Limited High-Side PCh Switch RoHS:否 制造商:Exar 输出端数量:1 开启电阻（最大值）:85 mOhms 开启时间（最大值）:400 us 关闭时间（最大值）:20 us 工作电源电压:3.2 V to 6.5 V 电源电流（最大值）: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOT-23-5 |
| MAX894LESA-TG116 | 制造商:Maxim Integrated Products 功能描述:CURRENT-LIMITED, HIGH-SIDE, P-CHANNEL DUAL SW - Bulk |
| MAX8951EVKIT+ | 制造商:Maxim Integrated Products 功能描述:PWM STEP DOWN CONVERTER - Boxed Product (Development Kits) |
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