MAX14588 Datasheet, PDF (11/15 Pages) Maxim Integrated Products – 1A Adjustable Overcurrent and Overvoltage Protector with High Accuracy

MAX14588
1A Adjustable Overcurrent and Overvoltage
Protector with High Accuracy
Detailed Description
The MAX14588 is an adjustable overvoltage and over-
current protection device designed to protect systems
against positive and negative input voltage faults up to
±40V, and features a low 190mΩ (typ) on-resistance
FET. If the input voltage exceeds the OVLO threshold
or falls below the UVLO, the internal FETs are turned off
to prevent damage to the protected components. If the
OVLO or the UVLO pin is set below the external OVLO
or UVLO select threshold (V_{SEL_OVLO}, V_{SEL_UVLO}), the
device automatically selects the internal ±5% accurate
trip thresholds. The internal OVLO threshold is preset to
33V (typ), and the internal UVLO threshold is preset to
19V (typ).
Current-Limit Type Select
The MAX14588 power-up current-limit default is continu-
ous mode when CLTS_MODE is low. After power up, the
current-limit type can be programmed externally through
CLTS1 and CLTS2 (Table 1). When CLTS_MODE is high,
CLTS1 and CLTS2 are sampled continuously. When
CLTS_MODE is low, CLTS1 and CLTS2 are sampled
only when V_IN-V_OUT < 0.6V. Connect CLTS1, CLTS2,
and CLTS_MODE to CLHS for logic-high or to GND for
logic-low.
Autoretry
When the current threshold is reached, the t_BLANK timer
begins counting. The FLAG asserts if the overcurrent con-
dition is present for t_BLANK .The timer resets if the over-
current condition disappears before tBLANK has elapsed.
A retry time delay, t_RETRY, is started immediately after
tBLANK has elapsed and during t_RETRY time, the FETs
are off. At the end of t_RETRY, the FETs are turned on
again. If the fault still exists, the cycle is repeated and the
FLAG stays low. When the fault is removed, the FETs stay
on. (Figure 1)
Table 1. Current-Limit Type Select
CLTS2
0
0
1
1
CLTS1
0
1
0
1
CURRENT-LIMIT TYPE
LATCH OFF
AUTORETRY
CONTINUOUS
CONTINUOUS
The autoretry feature reduces the system power in case
of overcurrent or short-circuit conditions. During tBLANK
time, when the switch is on, the supply current is held
at the current limit. During t_RETRY time, when the switch
is off, there is no current through the switch. Thus, the
output current is much less than the programmed current
limit. Calculate the average output current using the fol-
lowing equation.
I_LOAD
=
I_LIM



t
t _BLANK
BLANK ^{+ t} RETRY



With a 21ms (typ) t_BLANK and 620ms (typ) t_RETRY, the
duty cycle is 3.3%, resulting in a 96.7% power saving.
Latch-Off
When the current threshold is reached, the tBLANK timer
begins counting. The FLAG asserts if the overcurrent
condition is present for t_BLANK .The timer resets when
the overcurrent condition disappears before tBLANK has
elapsed. The switch turns off and stays off if the over-
current condition continues beyond the blanking time.
To reset the switch, either toggle the control logic EN or
HVEN or cycle the input voltage. (Figure 2)
Continuous
When the current threshold is reached, the MAX14588
limits the output current to the programmed current limit.
The FLAG asserts if the overcurrent condition is present
for t_BLANK and deasserts when the overload condition is
removed. (Figure 3)
Reverse-Current Block Enable (RIEN)
This feature disables the reverse-current protection and
enables reverse-current flow from OUT to IN. The reverse-
current block enable feature is useful in applications with
inductive loads.
Fault Flag Output
FLAG is an open-drain fault indicator output and requires
an external pull-up resistor to a DC supply. FLAG goes
low when any of the following conditions occur:
● The blanking time has elapsed
● The reverse-current protection has tripped
● The die temperature exceeds +150ºC
● SETI is connected to ground
● OVLO threshold is reached
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