MAX4945BELA+T Maxim Integrated Products, MAX4945BELA+T Datasheet - Page 6

• Manufacturer Part Number: MAX4945BELA+T
• Description: IC CTLR OVP W/FET 5.80V 8-UDFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX4945BELA+T

• Applications: *
• Mounting Type: Surface Mount
• Package / Case: 8-µDFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Overvoltage-Protection Controllers with
Internal FET
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 V
oscillator remains off, thus disabling the charge pump.
If V
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 V
V
is disabled.
The MAX4943–MAX4946/MAX4949 incorporate an
internal nFET with a 80mΩ (typ) R
internally driven by a charge pump that generates a 5V
Figure 2. Timing Diagram
6
OVLO
UVLO
_______________________________________________________________________________________
, ACOK is pulled high and the charge pump
< V
OUT
ACOK
IN
IN
IN
< V
< V
IN
UVLO
drops below V
OVLO
or if V
, the internal charge pump is
t
INDBC
t
ACOK
Internal Switch
IN
t
ON
Device Operation
>V
10% V
UVLO
80% V
ON
OVLO
IN
IN
. The switch is
or rises above
, the internal
t
OFF
t
INDBC
t
ACOK
voltage above the input voltage. The internal switch is
equipped with 1.2A (min) current-limit protection that
turns off the switch within 10µs (typ) during an overcur-
rent fault condition.
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.
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 V
then returns to the valid operating range.
t
OFF
OVLO
t
UVLO
INDBC
Autoretry
UVLO
Latch
and