MAX1607
USB Current-Limited Switch
in Pin-Compatible Package
counter starts. If the load fault persists beyond the
10ms overcurrent-blanking timeout, the OC output
asserts low. Ensure that the MAX1607 input is ade-
quately bypassed to prevent input glitches from trigger-
ing spurious OC outputs. Input voltage glitches less
than 150mV will not cause a spurious OC output. Load-
transient faults less than 10ms (typ) will not cause an
OC output assertion.
Only current-limit faults are blanked. Die overtempera-
ture faults and input voltage droops below the UVLO
threshold will cause an immediate OC output.
Applications Information
Input Capacitor
To limit the input voltage drop during momentary output
short-circuit conditions, connect a capacitor from IN to
GND. A 1µF ceramic capacitor will be adequate for
most applications; however, higher capacitor values will
further reduce the voltage drop at the input (Figure 2).
Output Capacitor
Connect a 0.1µF capacitor from OUT to GND. This
capacitor helps to prevent inductive parasitics from
pulling OUT negative during turn-off.
Layout and Thermal Dissipation
Important: Optimize the switch response time to output
short-circuit conditions by keeping 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 (no more than 5mm away). All
IN and OUT pins must be connected with short traces
to the power bus. Wide power-bus planes will provide
superior heat dissipation through the MAX1607’s IN
and OUT pins.
Under normal operating conditions, the package can
dissipate and channel heat away. Calculate the maxi-
mum power dissipation as follows:
P = (I
LIMIT
)
2
✕
R
ON
where I
LIMIT
is the preset current limit (1.0A max) and
R
ON
is the on-resistance of the switch (125mΩ max).
When the output is short circuited, foldback-current lim-
iting activates and the voltage drop across the switch
equals the input supply. The power dissipated across
the switch increases, as does the die temperature. If
the fault condition is not removed, the thermal-over-
load-protection circuitry activates (see Thermal
Shutdown section). Wide power-bus planes connected
to IN and OUT and a ground plane in contact with the
device will help dissipate additional heat.
Figure 2. Typical Application Circuit
