MAX4826–MAX4831
Detailed Description
The MAX4826–MAX4831 are forward-/reverse-current-
limited switches that operate from a +2.3V to +5.5V
input voltage range and guarantee a 50mA and 100mA
minimum current-limit threshold for different options.
The voltage drop across an internal sense resistor is
compared to two reference voltages to indicate a for-
ward- or reverse-current-limit fault. When the load cur-
rent exceeds the preset current limit for greater than
the fault-blanking time, the switch opens.
The MAX4827/MAX4829/MAX4831 have an autoretry
function that turns on the switch again after an internal
retry time expires. If the faulty load condition is still pre-
sent after the blanking time, the switch turns off again
and the cycle is repeated. If the faulty load condition is
not present, the switch remains on.
The MAX4826/MAX4828/MAX4830 do not have the
autoretry option, and the switch remains in latchoff mode
until ON or the input power is cycled from high to low
and then high again.
The undervoltage lockout (UVLO) circuit prevents erro-
neous switch operation when the input voltage goes too
low during startup conditions.
Reverse-Current Protection
The MAX4826–MAX4831 limit the reverse current (V
OUT
to V
IN
) from exceeding the maximum I
REV
value. The
switch is shut off and FFLG is asserted if the reverse-
current-limit condition persists for more than the blank-
ing time. This feature prevents excessive reverse cur-
rents from flowing through the device.
Switch-On/Off Control
Toggle ON high to enable the current-limited switches.
The switches are continuously on only if V
IN
exceeds
the UVLO threshold (typically 2V) and there is no fault.
When a forward-/reverse-current fault is present or the
die exceeds the thermal-shutdown temperature of
+150°C, OUT is internally disconnected from IN, and
the supply current decreases to 8µA (latchoff). The
switch is now operating in one of its off states. The
switch off state also occurs when driving ON low, thus
reducing the supply current (shutdown) to 0.01µA.
Table 1 illustrates the ON/OFF state of the MAX4826–
MAX4831 current-limit switches.
50mA/100mA Current-Limit Switches with
NO-LOAD Flag in µDFN
6 _______________________________________________________________________________________
Pin Description
Current-Limit Fault Output. FFLG is an open-drain output. FFLG goes low when the device stays in
forward- or reverse-current limit for more than the blanking time period. FFLG is high impedance
when a fault is not present or when ON is low.
No-Load Flag Output. NOLD is an open-drain output. NOLD goes low when a load of less than 10mA
(MAX4826–MAX4829) or 5mA (MAX4830/MAX4831) is delivered to the output. NOLD is high
impedance when a fault is not present or when ON is low.
