MAX14575A Datasheet, PDF (9/11 Pages) Maxim Integrated Products – 250mA to 2.5A Adjustable Current-Limit Switches

MAX14575A/MAX14575AL/
MAX14575B/MAX14575C
250mA to 2.5A Adjustable Current-Limit Switches
Latchoff (MAX14575B)
When the forward current reaches the current thresh-
old, the tBLANK timer begins counting (Figure 3). FLAG
asserts if an overcurrent condition is present for greater
than tBLANK time. The timer resets if the overcurrent con-
dition disappears before tBLANK has elapsed. The switch
turns off if the overcurrent condition continues beyond
the blanking time. Reset the switch by either toggling the
control logic (EN) or cycling the input voltage. If the die
temperature exceeds +160NC (typ) due to self-heating,
the MAX14575B goes into thermal-shutdown mode until
the die temperature drops by approximately 20NC.
Continuous Current Limit (MAX14575C)
When the forward current reaches the forward-current
threshold, the MAX14575C limits the output current to
the programmed current limit. FLAG asserts if the cur-
rent limit is present for tBLANK and deasserts when the
overload condition is removed. In this mode, if the die
temperature exceeds +160NC (typ) due to self-heating,
the MAX14575C goes into thermal-shutdown mode until
the die temperature drops by approximately 20NC.
Switch Enable Control (EN/EN)
The EN input for the MAX14575A/B/C and EN input for
the MAX14575AL control the internal switch. See Table 1.
Reverse Current Protection
The MAX14575A/MAX14575AL/MAX14575B/MAX14575C
feature a reverse current protection circuit that limits the
backflow current to 2FA when the reverse current protec-
tion circuitry has tripped. The switch turns off and FLAG
asserts without waiting for tBLANK to elapse. The switch
turns back on and FLAG deasserts when VOUT - VIN
drops below the reverse blocking threshold.
FLAG Indicator
FLAG is an open-drain fault indicator output and requires
an external pullup resistor to a DC supply. FLAG goes
low when any of the following conditions occur:
• An overcurrent condition after the blanking time has
elapsed and VIN - VOUT > VFA
Table 1. Switch Truth Table
MAX14575A/B/C
EN
0
1
MAX14575AL
EN
1
0
SWITCH
STATUS
OFF
ON
• The reverse current protection has tripped
• The die temperature exceeds +160NC
• SETI is connected to ground
Thermal Shutdown
Thermal shutdown circuitry protects the devices from
overheating. The switch turns off and FLAG goes low
immediately when the junction temperature exceeds
+160NC (typ). The MAX14575A/AL/C switches turn on
again after the device temperature drops by approxi-
mately 20NC (typ).
Applications Information
Setting the Current-Limit Threshold
Connect a resistor between SETI and ground to program
the current-limit threshold value for the MAX14575A/
MAX14575AL/MAX14575B/MAX14575C. Table 2 shows
current-limit thresholds for different resistor values at
SETI. Connecting SETI to ground asserts FLAG.
Use the following formula to calculate the current limit:
R _SET= _I(kΩ)
P(kV) _{− C(kΩ)}
I_LIM(mA)
Do not use an RSETI value smaller than 40kI.
Note: Connecting any capacitor larger than 20pF to SETI
can cause instability.
Table 2. Current-Limit Threshold vs.
Resistor Values
RSETI (kω)
510
470
402
301
261
200
150
100
90
85
75
64
57.6
53
CURRENT LIMIT (A)
0.26
0.28
0.33
0.45
0.51
0.625
0.86
1.32
1.45
1.55
1.75
2.02
2.26
2.5
Maxim Integrated
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