US2075A(2009) 查看數據表（PDF） - Unisonic Technologies
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US2075A Datasheet PDF : 10 Pages
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US2075A
CMOS IC
FUNCTIONAL DESCRIPTION
The UTC US2075A is dual P-Channel switch with active-low and active-high enabled inputs, respectively. Fault
conditions (such as UVLO, thermal shutdown and over-current) that appear will turn off the power switch, and the
FLAG pin will go low. Of course, the two internal FLAG circuits also operate respectively.
INPUT AND OUTPUT
IN (Input) is the power supply connection to the control circuitry and the source of the output MOSFET. OUTX
(Output) is the connection to the drain of the output MOSFET. In a typical application circuit, current flows through
the switch from IN to OUTX towards the load. If VOUT is greater than VIN when the switch is enabled, current will flow
from OUTX to IN since the MOSFET is bi-directional.
POWER ON AND OFF
The UTC US2075A performs a soft-start operation on power application, which is to prevent an over-current or
inrush-current from flowing through the switch from IN to OUTX towards to the load, while the high-capacity
capacitor is connected to the OUTX.
THERMAL SHUTDOWN
The UTC US2075A is internally protected against excessive power dissipation by thermal shutdown protection
circuit. If device junction temperature rise above approximately 150℃, both switches are turned off, both fault FLAG
outputs are activated, and they goes low. Hysteresis ensures that both switches turned off by thermal shutdown will
not be turned on again until the die temperature is reduced to 145℃. When the thermal shutdown circuit is activated,
the output pins are in the OFF status. However, the UTC US2075A enters the standby status when CTL pins are all
inactive.
CURRENT LIMIT
The current limit circuit is designed to protect the output MOSFET, the load and the IC supply from damage
caused by excessive currents. The current limit threshold is preset internally, If an over-current is detected, the IC
performs a slow-start operation again, it is assumed that output is short circuit, and FLAG pin will go low, FLAG
output is available to indicate fault conditions independently to the USB controller.
UNDER-VOLTAGE LOCKOUT
UVLO prevents the output MOSFET switch from turning on until input voltage exceeds 2.5V (typical). If input
voltage drops below 2.3V (typical), UVLO shuts off the both output MOSFET switches and signals the FLAG.
FAULT FLAG
The fault FLAG is an output with open-drain of N-channel. The fault FLAG is pulled down when any of the
conditions such as under-voltage, current limit and thermal shutdown. In a typical application circuit, the FALG pin
has a pull-up resistor of 10kΩ to input voltage.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
7 of 10
QW-R502-060,G
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