rt9703 ETC-unknow, rt9703 Datasheet - Page 11

• Manufacturer Part Number: rt9703
• Description: Smart Universal Power Switch With Flag
• Manufacturer: ETC-unknow

Applications Information
The RT9703 is a high-side, N-Channel, power switch
available with active-high enable input. Low R
80m
replace complex discrete on/off control circuitry.
Input and Output
V
circuitry and the drain of the MOSFET. V
the source of the MOSFET. In a typical application, current
flows through the switch from V
If V
V
Unlike a normal MOSFET, there is no a parasitic body
diode between drain and source of the MOSFET, the
RT9703 prevents reverse current flow if V
externally forced to a higher voltage than V
output disabled (V
D
D
D
Chip Enable Input
The switch will be disabled when the CE pin is in a logic
low condition. During this condition, the internal circuitry
and MOSFET are turned off, reducing the supply current
to 0.1 A typically. The maximum guaranteed voltage for
a logic low at the CE pin is 0.8V. A minimum guaranteed
voltage of 2V at the CE pin will turn the RT9703 back on.
Floating the input may cause unpredictable operation. CE
should not be allowed to go negative with respect to GND.
The CE pin may be directly tied to V
Soft-Start for Hot Plug-In Applications
In order to eliminate the upstream voltage droop caused
by the large inrush current during hot-plug events, the
“
from extremely large capacitive loads.
soft-start
IN
IN
Normal MOSFE T
Normal MOSFE T
OUT
(input) is the power source connection to the internal
since the MOSFET is bidirectional when on.
and full protection functions make it optimized to
is greater than V
”
G
G
G
feature effectively isolates the power source
CE
< 0.8V).
S
S
S
IN
, current will flow from V
D
D
D
IN
to V
IN
OUT
to keep the part on.
RT9704
RT9704
toward the load.
G
G
G
OUT
IN
(output) is
OUT
when the
DS(ON)dd
OUT
being
Preliminary
S
S
S
to
11
Fault Flag
The RT9703 provides a FLG signal pin which is an
N-Channel open drain MOSFET output. This open drain
output goes low when V
die temperature exceeds 130°C approximately. The FLG
output is capable of sinking a 10mA load to typically
150mV above ground. The FLG pin requires a pull-up
resistor, this resistor should be large in value to reduce
energy drain. A 100k pull-up resistor works well for most
applications. In the case of an over-current condition, FLG
will be asserted only after the flag response delay time,
t
upon valid over-current conditions and that erroneous
error reporting is eliminated.
For example, false over-current conditions may occur
during hot-plug events when a highly large capacitive load
is connected and causes a high transient inrush current
that exceeds the current limit threshold. The FLG
response delay time t
Under-Voltage Lockout
Under-Voltage lockout (UVLO) prevents the MOSFET
switch from turning on until input voltage exceeds
approximately 1.7V. If input voltage drops below
approximately 1.3V, UVLO turns off the MOSFET switch,
FLG will be asserted accordingly. Under- Voltage detection
functions only when the chip enable input is enabled.
Current Limiting and Short-Circuit Protection
The current limit circuitry prevents damage to the
MOSFET switch and external load. It is user adjust- able
with an external set resistor, R
the range of 500mA to 3.5A. The accuracy of current limit
set point may vary with operating temperature and supply
voltage. See
for further details.
D
, has elapsed. This ensures that FLG is asserted only
“
Typical Operating Characteristics
D
is typically 4.6ms.
OUT
< V
SET
IN
-1V, current limit or the
, I
LIMIT
RT9703
= 180k/R
”
SET
graph
in