參數(shù)資料
型號(hào)： MAX4789EUK
廠商： Maxim Integrated Products, Inc.
英文描述： 200mA/250mA/300mA Current-Limit Switches
中文描述： 200mA/250mA/300mA限流開關(guān)
文件頁(yè)數(shù)： 7/12頁(yè)
文件大?。?/td> 334K
代理商： MAX4789EUK
off.
FLAG
is an open-drain output transistor and requires
an external pullup resistor from
FLAG
to IN. During shut-
down (ON is low), the pulldown on
FLAG
output is
released in order to limit power dissipation.
FLAG
goes
low when any of the following conditions occur:
The die temperature exceeds the thermal-shutdown
temperature limit of +150°C.
The device is in current limit for more than the fault-
blanking period.
V
IN
is below UVLO threshold.
Autoretry (MAX4790/MAX4792/MAX4794)
When the forward or reverse current-limit threshold is
exceeded, t
BLANK
timer begins counting (Figure 2).
The timer resets if the overcurrent condition disappears
before t
BLANK
has elapsed. A retry time delay, t
RETRY
,
is started immediately after t
BLANK
has elapsed and
during that time, the switch is latched off. At the end of
t
RETRY
, the switch is turned on again. If the fault still
exists, the cycle is repeated. If the fault has been
removed, the switch stays on.
The autoretry feature saves system power in the case
of an overcurrent or short-circuit condition. During
t
BLANK
, when the switch is on, the supply current is at
the current limit. During t
RETRY
, when the switch is off,
the current through the switch is zero. Instead of
observing the full load current, the switch sees the
equivalent load current times duty cycle or I
SUPPLY
=
I
LOAD
t
BLANK
/(t
BLANK
+ t
RETRY
). With a typical
t
BLANK
= 37ms and typical t
RETRY
= 259ms, the duty
cycle is 12%, which results in an 88% power savings
over the switch being on the entire time. The duty cycle
is consistent across the process and devices.
Latch Off (MAX4789/MAX4791/MAX4793)
When the forward or reverse current-limit threshold is
exceeded, t
BLANK
timer begins counting. The timer
resets if the overcurrent condition disappears before
t
BLANK
has elapsed. The switch is shut off if the over-
current condition continues up to the end of the blank-
ing time. Reset the switch by either toggling ON (Figure
3a) or cycling the input voltage below UVLO, typically
2V (Figure 3b).
Fault Blanking
The MAX4789–MAX4794 feature 14ms (min) fault blank-
ing. Fault blanking allows current-limit faults, including
momentary short-circuit faults that occur when hot
swapping a capacitive load, and also ensures that no
fault is issued during power-up. When a load transient
causes the device to enter current limit, an internal
counter starts. If the load-transient fault persists beyond
the fault-blanking timeout, the MAX4789/MAX4791/
MAX4793
FLAG
asserts low. Load-transient faults less
than t
BLANK
do not cause a
FLAG
output assertion. Only
current-limit faults are blanked.
A thermal fault and input voltage drops below the
UVLO threshold cause
FLAG
to assert immediately and
do not wait for the blanking time.
Thermal Shutdown
The MAX4789–MAX4794 have a thermal shutdown fea-
ture to protect the devices from overheating. The switch
turns off and
FLAG
goes low immediately (no fault blank-
ing) when the junction temperature exceeds +150°C.
The switch turns back on when the device temperature
drops approximately 15°C.
M
200mA/250mA/300mA Current-Limit Switches
_______________________________________________________________________________________
7
ON
Low
High
High
FAULT
X
SWITCH ON/OFF
SUPPLY CURRENT MODE
Shutdown
Shutdown
Latch off
Latch off
OFF
OFF
OFF immediately (t
BLANK
period does not apply)
OFF after t
BLANK
period has elapsed
ON during t
BLANK
period, OFF during t
RETRY
period for the
MAX4790, MAX4792, and MAX4794; cycle repeats until fault
is removed
Undervoltage Lockout
Thermal
High
Current Limit
See the
Autoretry
section
Table 1. MAX4789–MAX4794 Switch Truth Table
LOAD
CURRENT
SWITCH
STATUS
t
BLANK
OFF
ON
t
RETRY
CURRENT
LIMIT
SHORT
CONDITION
REMOVED
t
BLANK
t
BLANK
Figure 2. MAX4790/MAX4792/MAX4794 Autoretry Fault
Blanking Diagram
相關(guān)PDF資料
PDF描述
MAX4789EUS 200mA/250mA/300mA Current-Limit Switches
MAX4793EUK 200mA/250mA/300mA Current-Limit Switches
MAX4793EUS 200mA/250mA/300mA Current-Limit Switches
MAX4794EUS 200mA/250mA/300mA Current-Limit Switches
MAX478 Dual, Single-Supply,Precision Op Amps(單電源，輸入失調(diào)電壓70~250μV,等效輸入噪聲電壓49nV/√Hz,增益帶寬積60KHz的運(yùn)算放大器)
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX4789EUK+T 功能描述:電源開關(guān) IC - 配電 200/250/300mA Crnt Limit Switch RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻（最大值）:85 mOhms 開啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)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(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
MAX4789EUK-T 功能描述:電源開關(guān) IC - 配電 RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻（最大值）:85 mOhms 開啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)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(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
MAX4789EUS 制造商:Maxim Integrated Products 功能描述:- Cut Tape Product
MAX4789EUS-T 功能描述:電源開關(guān) IC - 配電 RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻（最大值）:85 mOhms 開啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)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(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5
MAX478ACPA 功能描述:運(yùn)算放大器 - 運(yùn)放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel
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