MAX14544 Maxim, MAX14544 Datasheet - Page 9

• Manufacturer Part Number: MAX14544
• Description: The MAX14544/MAX14545 are overcurrent detection switches that can provide power to external accessories while preventing the host device from damage due to faulty overload conditions
• Manufacturer: Maxim

fault-blanking timeout, FLAG asserts low. FLAG is not
asserted when load-transient fault is less than t
The fault blanking time only applies to forward current-
limit faults.
A reverse current-limit fault, thermal fault, or OVP fault
causes FLAG to assert immediately and does not wait
for the blanking time.
The MAX14544/MAX14545 have a thermal-shutdown
feature to protect the devices from overheating. The
device turns off and FLAG goes low immediately (no
fault blanking) when the junction temperature exceeds
+150NC. The MAX14544/MAX14545 turns back on when
the device temperature drops approximately 15NC.
The MAX14544/MAX14545 feature an overvoltage pro-
tection. When IN goes above V
switch turns off and FLAG goes low immediately with
no fault-blanking time. When IN drops below V
(1.8V min), the switch turns off but FLAG stays high. The
MAX14544/MAX14545 turns back on when IN is in the
operating range.
To limit the input-voltage drop during momentary output
short-circuit conditions, connect a capacitor from IN to
GND. A 10FF ceramic capacitor is adequate for most
applications; however, higher capacitor values further
reduce the voltage drop at the input and are recom-
mended for lower voltage applications.
Connect a 1FF ceramic capacitor from OUT to GND.
This capacitor helps prevent inductive parasitics from
pulling OUT negative during turn-off, thus preventing
28V-Capable, I
Applications Information
Thermal Shutdown
OVLO
Output Capacitor
OVLO and UVLO
Input Capacitor
(6.0V max), the
LIM
BLANK
UVLO
.
V
the MAX14544/MAX14545 from tripping erroneously. If
the load capacitance is too large, then current may not
have enough time to charge the capacitance and the
device assumes that there is faulty load condition. The
maximum capacitive load value that can be driven from
OUT is obtained by the following formula:
To optimize the switch response time to output short-
circuit conditions, it is very important to keep all traces
as short as possible to reduce the effect of undesirable
parasitic inductance. Place input and output capacitors
as close as possible to the device. IN and OUT must be
connected with short traces to the power bus.
During normal operation, the power dissipation is small
and the package temperature change is minimal. If the
output is continuously shorted to ground at the maximum
supply voltage, the operation of the switches with the
autoretry option does not cause problems because the
total power dissipated during the short is scaled by the
duty cycle:
where V
10.5ms, and t
Attention must be given to the MAX14545 where the
latchoff condition can be manually reset by toggling EN
from high to low. If the latchoff time duration is not suf-
ficiently high, it is possible for the device to reach the
thermal-shutdown threshold and never be able to turn
the device on until it cools down.
BUS
P
MAX
IN_MAX
=
Accessory Switch
C
V
IN_MAX
MAX
RETRY
Layout and Thermal Dissipation
= 5.5V, I
<
t
RETRY
I
= 661.5ms.
FWD_MIN
×
I
OUT_MAX
OUT_MAX
+
t
BLANK
×
V
IN
t
BLANK_MIN
×
t
BLANK
= 600mA, t
=
51.6mW
BLANK
=
9