
M
USB Current-Limited Switch
in Pin-Compatible Package
6
_______________________________________________________________________________________
Detailed Description
The MAX1607 P-channel MOSFET power switch limits
output current to 0.7A min and 1.0A max. When the out-
put current is increased beyond the current limit (I
LIMIT
),
the current also increases through the replica switch
(I
OUT
/ 6500). The current-limit error amplifier compares
the voltage to the internal 1.24V reference and regu-
lates the current back to the I
LIMIT
(Figure 1).
These switches are not bidirectional; therefore, the
input voltage must be higher than the output voltage.
Continuous Short-Circuit Protection
The MAX1607 is a short-circuit-protected switch. In the
event of an output short-circuit condition, the current
through the switch is foldback-current-limited to 500mA
continuous.
Thermal Shutdown
The MAX1607 has a thermal shutdown feature. The
switch turns off and the
OC
output goes low immediate-
ly (no overcurrent blanking) when the junction tempera-
ture exceeds +165°C. When the MAX1607 cools 20°C,
the switch turns back on. If the fault short-circuit condi-
tion is not removed, the switch will cycle on and off,
resulting in a pulsed output.
OC
Indicator
The MAX1607 provides an overcurrent output (
OC
). A
100k
pull-up resistor from
OC
to IN provides a logic
control signal. This open-drain output goes low when
any of the following conditions occur:
The input voltage is below the 2.4V undervoltage-
lockout (UVLO) threshold.
The die temperature exceeds the thermal shutdown
temperature limit of +165°C.
The device is in current limit for greater than 10ms.
OC
Blanking
The MAX1607 features 10ms overcurrent blanking.
Blanking allows brief current-limit faults, including
momentary short-circuit faults that occur when hot-
swapping a capacitive load, and also ensures that no
OC
is issued during power-up. When a load transient
causes the device to enter current limit, an internal
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
NAME
FUNCTION
1
GND
Ground
2, 3
IN
Input. P-channel MOSFET source—connect all IN pins together and bypass with a 1μF capacitor to ground.
PIN
4
EN
Active-Low Switch Enable Input. A logic low turns on the switch.
5
OC
Overcurrent-Indicator Output. This open-drain output goes low when the device is in thermal shutdown or
undervoltage lockout, or during a sustained (>10ms) current-limit condition.
6, 7, 8
OUT
Switch Output. P-channel MOSFET drain—connect all OUT pins together and bypass with a 0.1μF
capacitor to ground.
Pin Description
MAX1607
P
P
P
OUT
GND
1.24V
N
ON
CURRENT-LIMIT
AMPLIFIER
REPLICA
AMPLIFIER
ON
EN
HOT
IN
CONTROL
CIRCUITRY
OC
10ms
TIMER
Figure 1. Functional Diagram