參數(shù)資料
型號: MAX4944BELA+T
廠商: Maxim Integrated Products
文件頁數(shù): 7/10頁
文件大?。?/td> 0K
描述: IC CTLR OVP W/FET 6.35V 8-UDFN
產(chǎn)品培訓(xùn)模塊: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
標(biāo)準(zhǔn)包裝: 2,500
類型: 過壓保護(hù)控制器
應(yīng)用: 手機(jī),數(shù)碼相機(jī),媒體播放器
安裝類型: 表面貼裝
封裝/外殼: 8-WFDFN
供應(yīng)商設(shè)備封裝: 8-uDFN(2x2)
包裝: 帶卷 (TR)
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
Device Operation
The MAX4943–MAX4946/MAX4949 have an internal
oscillator and charge pump that control the turn-on
of the internal switch. The internal oscillator controls
the timers that enable the turn-on of the charge pump
and controls the state of the open-drain
ACOK
output. If VIN < VUVLO or if VIN >VOVLO, the internal
oscillator remains off, thus disabling the charge pump.
If VUVLO < VIN < VOVLO, the internal charge pump is
enabled. The charge-pump startup, after a 15ms (typ)
internal delay, turns on the internal switch (see Figure 2).
ACOK is held high during startup until the ACOK 30ms
(typ) blanking period expires. At this point, the device is
in its on state.
At any time, if VIN drops below VUVLO or rises above
VOVLO, ACOK is pulled high and the charge pump
is disabled.
Internal Switch
The MAX4943–MAX4946/MAX4949 incorporate an
internal nFET with a 80mΩ (typ) RON. The switch is
internally driven by a charge pump that generates a 5V
voltage above the input voltage. The internal switch is
equipped with 1.2A (min) current-limit protection that
turns off the switch within 10s (typ) during an overcur-
rent fault condition.
Autoretry
The MAX4943–MAX4946 have an overcurrent autoretry
function that turns on the switch again after a 15ms (typ)
retry time (see Figure 3). If the faulty load condition is still
present after the blanking time, the switch turns off again
and the cycle is repeated. The fast turn-off time and
15ms retry time result in a very low duty cycle to keep
power consumption low. If the faulty load condition is not
present, the switch remains on.
Latch
The MAX4944B/MAX4945B/MAX4949 do not have the
autoretry function, and the switch latches off after an
overcurrent fault. The switch remains off until the over-
current fault has been removed. The switch turns back
on when the adapter voltage goes below VUVLO and
then returns to the valid operating range.
Overvoltage-Protection Controllers with
Internal FET
6
_______________________________________________________________________________________
OVLO
UVLO
tINDBC
tON
IN
OUT
ACOK
tINDBC
tOFF
tINDBC
80% VIN
tACOK
tOFF
tACOK
10% VIN
Figure 2. Timing Diagram
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