Datasheet

UNISONIC TECHNOLOGIES CO., LTD
US202
Preliminary
CMOS IC
100mΩ POWER DISTRIBUTION
SWITCHES

DESCRIPTION
The US202 is a power distribution switch. It is particularly suitable
for self-powered and bus-powered USB (Universal Series bus)
applications. It has 23μA low quiescent supply current that meets the
requirements of battery-powered portable equipments.
A built-in charge pump is used to drive the N-channel N-MOSFET
that is free of parasitic body diode to eliminate any reversed current
flow across the switch when it is powered off.
The US202 incorporates some protection circuits such as current
limit and short protection circuits, soft start circuit, thermal shutdown
and UVLO (Under-voltage Lockout) protection circuits. The thermal
shutdown circuits protect this device from damage when over current
occurs, and the soft start circuits are used to prevent inrush current
when plug-in event occurs.
The US202 can be used in such applications such as
battery-powered equipments, motherboard USB power switchs, USB
device power switchs, hot-plug power supplies, battery-charger
circuits and so on.

FEATURES
* Input Voltage Varies From 2.2V to 6V
* Guaranteed Continuous Current: 1.0A
* High-Side NMOSFET: 85mΩ (TYP)
* Soft Start
* Current Limit:1.5A
* Thermal Protection
* Low Supply Current: 23μA

ORDERING INFORMATION
Ordering Number
US202XG-AF5-R
www.unisonic.com.tw
Copyright © 2016 Unisonic Technologies Co., Ltd
Package
SOT-25
Packing
Tape Reel
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US202
Preliminary

MARKING

PIN CONFIGURATION

EN
5
4
1
2
3
VOUT
GND
VIN
PIN DESCRIPTION
PIN NO.
1, 5
2
3
4

VOUT
CMOS IC
PIN NAME
VOUT
GND
VIN
EN
DESCRIPTION
Output Voltage
Ground
Power Input
Chip Enable (Active High)
BLOCK DIAGRAM
VIN
Bias
Oscillator
Charge
Pump
Current
Limiting
Current sense
Control
VOUT
VOUT
Thermal
Detection
NMOSFET
GND
EN
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
Preliminary
CMOS IC
ABSOLUTE MAXIMUM RATING
PARAMETER
SYMBOL
RATINGS
UNIT
Supply Voltage
VIN
7
V
Chip Enable
VCE
-0.3 ~ 7
V
Power Dissipation (TA = 25°C)
PD
0.25
W
Junction Temperature
TJ
-20 ~ 100
°C
Storage Temperature
TSTG
-65 ~ 150
°C
Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.

ELECTRICAL CHARACTERISTICS
(VIN = 5V, CIN = COUT = 1μF, TA = 25°C, unless otherwise specified)
PARAMETER
SYMBOL
TEST CONDITIONS
Input Voltage Range
VIN
Output NMOSFET RDS(ON)
RDS(ON) IL = 1A
VIN= 3V
Supply Current
VIN= 5V
Output Turn-On Rising Time
TR
RL= 10Ω, 90% Settling
Current Limit Threshold
ILIMIT
VOUT = 0V, measured prior to
Short-Circuit Fold Back Current
IOS
thermal shutdown
EN Input High Threshold
VIH
EN Input Low Threshold
VIL
Shutdown Supply Current
IOFF
EN = “0”
Output Leakage Current
II(LEAK)
EN = “0”, VOUT = 0V
VIN Under Voltage Lockout
UVLO
VIN Under Voltage Hysteresis
Thermal Limit
TSD
Thermal Limit Hysteresis
∆TSD
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
MIN
2.2
1.1
TYP
85
19
23
400
1.5
MAX UNIT
6
V
100 mΩ
40
µA
45
µS
2
A
1.0
A
2.0
1.3
0.1
0.5
1.8
100
130
20
0.8
1
10
V
V
µA
µA
V
mV
°C
°C
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Preliminary
CMOS IC
TEST CIRCUIT
IOUT
VIN
VEN
CIN
1µF
VIN
VOUT
EN
VOUT
+
GND
On
CL
1µF
VOUT
+
RL
IL
Off
Test Circuit 2
Test Circuit 1 is performed by charging an external tank of bulk capacitor to the input then applying this voltage to
the input of the unit.
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US202

Preliminary
CMOS IC
APPLICATION INFORMATION
The UTC US202 is a high-side single N-Channel MOSFET switch with active-high enable input.
Input and Output
VIN pin (input) is the power supply connection to the circuitry and the drain of the output MOSFET. VOUT pin (output)
is the source of the output MOSFET. In a typical circuit, current flows through the switch from VIN to VOUT toward the
load. Both VOUT pins must be short on the board and connected to the load and so do both VIN pins but connected to
the power source.
Thermal Shutdown
Thermal shutdown is used to turn off the output MOSFET when the if the temperature is higher than130°C, 20°C
of hysteresis prevents the switch turn on until the die temperature drops to 110°C.
Soft Start
When hot-plug events occur, the soft start is used to eliminate the upstream voltage droop due to the inrush
current. The soft-start protects power supplies from damage caused by highly capacitive loads.
Under-Voltage Lockout
UVLO (Under voltage Lockout) turn off the MOSFET switch once the input voltage falls below 1.8V (TYP.) and if
the input voltage exceeds 1.8V, the switch will be turned on.
Current Limiting and Short Protection
The current limit threshold is preset internally. The minimum value is 1.1A. The current limit circuit protects this
device from damage resulting from undesired excess inrush current, which is encountered during hot plug-in events.
The output current is limited to approximately 1.5A (TYP). When the output is short to ground, it will limit to a
constant current 1A until thermal shutdown or short condition removed.
VIN
CIN
1µF
VEN
VIN
VOUT
EN
VOUT
GND
On
VOUT
COUT
1µF
Off
Figure 1. High Side Power Switch with Chip Enable Control
Filtering
During the hot-plug events, in order to limit the input voltage drop, a 1μF ceramic capacitor is recommended to
be placed between VIN to GND. However special care must be taken to the values of the capacitor, because higher
capacitor values will further reduce the voltage drop at the input.
In order to prevent inductive parasitic from pulling VOUT negative during turn-off or EMI damage to other
components during the hot detachment, it’s better to connect a sufficient capacitor from VOUT to GND. This capacitor
is also necessary for meeting the USB specification during hot plug-in operation.
If the UTC US202 is implanted in device and application, minimum 1μF capacitor from VOUT to GND is
recommended and higher capacitor values are also preferred.
Choosing these capacitors properly is critical. A lower ESR on the capacitor can get a lower IR drop during the
operation, so the Effective Series Resistance (ESR) of the capacitors must be considered.
For ferrite beads, if they are in series with all power and ground lines, the EMI will be eliminated or reduced. The
DC resistance of the wire kept to a minimum to reduce the voltage drop should be considered in choosing ferrite
beads.
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
Preliminary
CMOS IC
APPLICATION INFORMATION (Cont.)
Reverse Current Preventing
Since the UTC US202’s MOSFET is bi-directional, it allows the voltage on VOUT pin is higher than that on VIN pin.
In order to avoid reverse current occur, turn off this switch or connect VIN to a fixed voltage less than 1.3V.
Layout and Thermal Dissipation
The switch should be placed as close to the USB connector as possible and all traces should be as short as
possible to reduce the effect of undesirable parasitic inductance.
Also, place the output capacitor and ferrite beads to the USB connector as close to as possible.
If ferrite beads are used, use wires kept to a minimum resistance and large solder pads to minimize connection
resistance.
If the package is with dual VOUT or VIN pins, short both the same function pins as Fig.1 or Fig.2 to reduce the
internal turn-on resistance. If the output power is delivered to two individual ports, it is specially necessary to short
both VOUT pin at the switch output side in order to protect the switch when each port are plug-in separately.
Under normal operating conditions, the package can dissipate the channel heat away. Wide power bus planes
connected to VIN and VOUT and a ground plane in contact with the device will help dissipate additional heat.

TYPICAL APPLICATION CIRCUIT
VIN
CIN
1µF
VIN
VOUT
EN
VOUT
GND
VOUT
COUT (Note)
470µF
Note: 470µF, Low ESR Electrolytic
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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www.unisonic.com.tw
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