參數資料
型號: MAX891LEUA
廠商: MAXIM INTEGRATED PRODUCTS INC
元件分類: 穩(wěn)壓器
英文描述: Single Peripheral Driver
中文描述: SWITCHING REGULATOR, PDSO8
封裝: 1.11 MM HEIGHT, ULTRA SMALL, UMAX-8
文件頁數: 6/8頁
文件大?。?/td> 734K
代理商: MAX891LEUA
M
1.2A, Current-Limited, High-Side
P-Channel Switch with Thermal Shutdown
6
_______________________________________________________________________________________
Pin Description
Switch Output. P-channel MOSFET drain. Bypass OUT with a 0.1
μ
F capacitor to ground.
OUT
6, 7
Fault-Indicator Output. This open-drain output goes low when in current limit or when the die temperature
exceeds +135°C.
FAULT
8
Set Current-Limit Input. A resistor from SET to ground sets the current limit for the switch.
R
SET
= 1.38 x 10
3
/ I
LIMIT,
where I
LIMIT
is the desired current limit in amperes.
SET
5
Ground
GND
4
PIN
1, 2
Active-Low Switch On Input. A logic low turns the switch on.
ON
3
Input. P-channel MOSFET source. Bypass IN with a 1
μ
F capacitor to ground.
IN
FUNCTION
NAME
Detailed Description
The MAX890L P-channel MOSFET power switch limits
output current to a programmed level. When the output
current is increased beyond the programmed current
limit, or 1.2A (I
MAX
), the current also increases through
the replica switch (I
OUT
/1110) and through R
SET
(Figure 1). The current-limit error amplifier compares
the voltage across R
SET
to the internal +1.24V refer-
ence, and regulates the current back to the lesser of
the programmed limit (I
LIMIT
) or 1.2A.
This switch is not bidirectional; therefore, the input volt-
age must be higher than the output voltage.
Setting the Current Limit
The MAX890L features internal current-limiting circuitry
with a maximum programmable value (I
MAX
) of 1.2A.
For best performance, set the current limit (I
LIMIT
)
between 0.2 I
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
) from
SET to ground (Figure 2) as follows:
I
SET
= I
LIMIT
/ 1110
R
SET
= 1.24V / I
8
= 1.38 x 10
3
/ I
LIMIT
where I
LIMIT
is the desired current limit.
Short-Circuit Protection
The MAX890L is a short-circuit-protected switch. In the
event of an output short circuit or current-overload con-
dition, the current through the 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 will set the current limit back to I
LIMIT
.
For a high dV
DS
/dt during an output short-circuit condi-
tion, the switch turns off and disconnects the input supply
from the output. The current-limiting amplifier then slow-
ly turns the switch on with the output current limited to
1.5 x I
LIMIT
. When the fault condition is removed, the
current limit is set back to I
LIMIT
. Refer to Output Short-
Circuit Fast-Loop Response and Output Over-Load
MAX890L
P
P
P
R
SET
SET
OUT
GND
1.24V
N
FAULT
ON
ON
CURRENT-LIMIT
AMPLIFIER
REPLICA
AMPLIFIER
ON
HOT
IN
CONTROL
CIRCUITRY
Figure 1. Functional Diagram
相關PDF資料
PDF描述
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MAX891LEUA+T 功能描述:電源開關 IC - 配電 Current-Limited High-Side PCh Switch RoHS:否 制造商:Exar 輸出端數量:1 開啟電阻(最大值):85 mOhms 開啟時間(最大值):400 us 關閉時間(最大值):20 us 工作電源電壓:3.2 V to 6.5 V 電源電流(最大值): 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-23-5
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