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PDF RT9702A Data sheet ( Hoja de datos )
| Número de pieza | RT9702A | |
| Descripción | 500mA/1.1A High Side Power Switches | |
| Fabricantes | RichTek | |
| Logotipo |  |
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RT9702/A
80mΩ, 500mA/1.1A High Side Power Switches with Flag
General Description
Features
The RT9702 and RT9702A are cost-effective, low voltage,
single N-Channel MOSFET high-side power switches,
optimized for self-powered and bus- powered Universal
Serial Bus (USB) applications. The RT9702/A equipped
with a charge pump circuitry to drive the internal MOSFET
switch; the switch's low RDS(ON), 80mΩ, meets USB
voltage drop requirements; and a flag output is available
to indicate fault conditions to the local USB controller.
Additional features include soft-start to limit inrush current
during plug-in, thermal shutdown to prevent catastrophic
switch failure from high current loads, under-voltage
lockout (UVLO) to ensure that the device remains off
unless there is a valid input voltage present, fault current
is limited to typically 800mA for RT9702 in single port and
1.5A for RT9702A in dual ports in accordance with the
USB power requirements, lower quiescent current as 25μA
making this device ideal for portable battery-operated
equipment.
The RT9702/A is available in SOT-23-5 and TSOT-23-5
packages requiring minimum board space and smallest
components.
z Compliant to USB Specifications
z Built-In (Typically 80mΩ) N-Channel MOSFET
z Output Can Be Forced Higher Than Input (Off-State)
z Low Supply Current :
25uA Typical at Switch On State
1uA Typical at Switch Off State
z Guaranteed 500mA/RT9702 and 1.1A/RT9702A
Continuous Load Current
z Wide Input Voltage Ranges : 2V to 5.5V
z Open-Drain Fault Flag Output
z Hot Plug-In Application (Soft-Start)
z 1.7V Typical Under Voltage Lockout (UVLO)
z Current Limiting Protection
z Thermal Shutdown Protection
z Reverse Current Flow Blocking (no body diode)
z Smallest SOT-23-5 and TSOT-23-5 Packages
Minimizes Board Space
z UL Approved−E219878
z TUV IEC60950-1 : 2005 Certified
z RoHS Compliant and 100% Lead (Pb)-Free
Applications
Ordering Information
RT9702/A
Package Type
B : SOT-23-5
J5 : TSOT-23-5
z USB Bus/Self Powered Hubs
z USB Peripherals
z ACPI Power Distribution
z PC Card Hot Swap
z Notebook, Motherboard PCs
Lead Plating System
z Battery-Powered Equipment
P : Pb Free
z Hot-Plug Power Supplies
G : Green (Halogen Free and Pb Free) z Battery-Charger Circuits
1.1A Output Current
Note :
500mA Output Current
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
` Suitable for use in SnPb or Pb-free soldering processes.
DS9702/A-15 April 2011
www.richtek.com
1
1 page  
RT9702/A
Parameter
S ymbo l
Test Conditions
Min Typ Max Unit
Under Voltage Lockout
Under Voltage Hysteresis
Thermal Shutdown Protection
Thermal Shutdown Hysteresis
VUV LO
ΔVUVLO
TSD
ΔTSD
VIN Increasing
VIN Decreasing
1.3 1.7
-- 0.1
-- 130
-- 20
--
--
--
--
V
V
°C
°C
Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for
stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may remain possibility to affect device reliability.
Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective thermal conductivity single layer test board of
JEDEC 51-3 thermal measurement standard.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Note 5. The FLAG delay time is input voltage dependent, see“ Typical Operating Characteristics” graph for further details.
DS9702/A-15 April 2011
www.richtek.com
5
5 Page 
Applications Information
The RT9702 and RT9702A are single N-Channel MOSFET
high-side power switches with active-high enable input,
optimized for self-powered and bus-powered Universal
Serial Bus (USB) applications. The RT9702/A equipped
with a charge pump circuitry to drive the internal NMOS
switch; the switch's low RDS(ON), 80mΩ, meets USB
voltage drop requirements; and a flag output is available
to indicate fault conditions to the local USB controller.
Input and Output
VIN (input) is the power source connection to the internal
circuitry and the drain of the MOSFET. VOUT (output) is
the source of the MOSFET. In a typical application, current
flows through the switch from VIN to VOUT toward the load.
If VOUT is greater than VIN, current will flow from VOUT to
VIN since the MOSFET is bidirectional when on.
Unlike a normal MOSFET, there is no a parasitic body
diode between drain and source of the MOSFET, the
RT9702/A prevents reverse current flow if VOUT being
externally forced to a higher voltage than VIN when the
output disabled (VEN < 0.8V).
D SD
S
G
Normal MOSFET
G
RT9702/A
Chip Enable Input
The switch will be disabled when the EN pin is in a logic
low condition. During this condition, the internal circuitry
and MOSFET are turned off, reducing the supply current
to 0.1μA typical. The maximum guaranteed voltage for a
logic low at the EN pin is 0.8V. A minimum guaranteed
voltage of 2V at the EN pin will turn the RT9702/A back
on. Floating the input may cause unpredictable operation.
EN should not be allowed to go negative with respect to
GND. The EN pin may be directly tied to VIN to keep the
part on.
RT9702/A
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
“soft-start” feature effectively isolates the power source
from extremely large capacitive loads, satisfying the USB
voltage droop requirements.
Fault Flag
The RT9702/A provides a FLG signal pin which is an N-
Channel open drain MOSFET output. This open drain
output goes low when VOUT < VIN – 1V, current limit or
the die temperature exceeds 130°C approximately. The
FLG output is capable of sinking a 10mA load to typically
200mV above ground. The FLG pin requires a pull-up
resistor, this resistor should be large in value to reduce
energy drain. A 100kΩ 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,
tD, has elapsed. This ensures that FLG is asserted only
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 extremely large capacitive
loads are connected and causes a high transient inrush
current that exceeds the current limit threshold. The FLG
response delay time tD is typically 10ms.
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 switch is enabled.
Current Limiting and Short-Circuit Protection
The current limit circuitry prevents damage to the MOSFET
switch and the hub downstream port but can deliver load
current up to the current limit threshold of typically 800mA
through the switch of RT9702 and 1.5A for RT9702A
respectively. When a heavy load or short circuit is applied
to an enabled switch, a large transient current may flow
DS9702/A-15 April 2011
www.richtek.com
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet RT9702A.PDF ] | |
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