Datasheet

UNISONIC TECHNOLOGIES CO., LTD
US211/A/B/C
CMOS IC
HIGH-SIDE POWER SWITCHES
WITH FLAG

DESCRIPTION
The UTC US211/A/B/C series are 80mΩ high-side power
switches. There’s internal single low voltage N-Channel MOSFET
which makes it an ideal for all USB applications. This MOSFET
should be driven by a charge pump circuitry inside. Its switch on
resistance is as low as 80mΩ which we know specially meets the
drop voltage for USB applications.
The flag pin can output an open-drain fault flag to next controller.
There’re lots internal special ways for protecting the chip’s
operation.
When in hot-plug events, there’s large current which can create
the upstream voltage droop to match the USB’s voltage droop
requirements and soft-start for isolating the power source.
As soon as the die temperature is higher than 130℃, the internal
shutdown circuit will work.
Only when there’s a normal input voltage in the VIN pin, the
UVLO (under-voltage lockout, 1.3V/2.5V typ.) can make sure the
chip is till in the off state.
Because of the requirement of USB power the fault current
should be ensured less than 0.6A/1.1A (UTC US211/A, single port)
and 1.3A /1.5A (UTC US211B/C, dual ports).

FEATURES
* 80mΩ(Typ) N-Channel MOSFET
* Supply Current:
– Switch On : 25μA(Typ)
– Switch Off : 1μA (Typ)
* Load Current 500mA for US211 and 1.0A for US211A/B/C
* Input Voltage from 2V ~ 5.5V
* In Off-State: Output Voltage can be Higher than Input

ORDERING INFORMATION
Ordering Number
US211XXG-AF5-R
www.unisonic.com.tw
Copyright © 2014 Unisonic Technologies Co., Ltd
Package
SOT-25
Packing
Tape Reel
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QW-R502-A67.C
US211/A/B/C

CMOS IC
MARKING
4
5
Current Code:
1: 0.6A, A: 1.1A,
B: 1.3A, C: 1.5A
U1
1
G
2
Logic Level Enable Pin
3

PIN CONFIGURATION

PIN DESCRIPTION
PIN NO
1
2
PIN NAME
CTL
GND
3
FLG
Open-drain fault flag output
4
5
VIN
VOUT
Power input voltage
Output voltage

DESCRIPTION
Enable Input pin, H: High active, L: Low active
Ground
BLOCK DIAGRAM
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US211/A/B/C

CMOS IC
ABSOLUTE MAXIMUM RATING(TA=25°C, unless otherwise specified)
PARAMETER
SYMBOL
Supply Voltage
VCC
Input/Output Pins
VCTL
VCTL
V FLG
V FLG
RATINGS
6.5
+2 ~ +5.5 (Note 2)
-0.3~ +6.5
0 ~ +5.5 (Note 2)
UNIT
V
V
V
V
6.5
V
150
°C
Junction Temperature
TJ
-20 ~ +100 (Note 2)
°C
Storage Temperature
TSTG
-65 ~ +150
°C
Note: 1. 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.
2. The device is not guaranteed to function when it’s beyond its operating conditions.

THERMAL DATA
PARAMETER
Junction to Ambient
Junction to Case

SYMBOL
θJA
θJC
RATINGS
260
81
UNIT
°C/W
°C/W
ELECTRICAL CHARACTERISTICS
PARAMETER
ENABLE INPUT
CTL Threshold
SYMBOL
Low
High
CTL Input Current
UNDER VOLTAGE LOCK
Under-Voltage Lockout
Under-Voltage Hysteresis
SUPPLY CURRENT
Supply Current
Output Leakage Current
CURRENT LIMIT
VIL
VIH
II(CTL)
TEST CONDITIONS
VIN=2V~5.5V, Switch OFF
VIN=2V~5.5V, Switch ON
VCTL=0V~5.5V
0.8
VIN increasing
VIN decreasing
ISW(ON)
ISW(OFF)
IO(LEAK)
Switch on, VOUT=OPEN, VCTL =VIN or GND
Switch off, VOUT=OPEN, VCTL =VIN or GND
VCTL=0V, RLOAD=0Ω
ILIMIT
Short Circuit Fold-Back Current
ISC(FB)
0.01
V
V
µA
2.1
0.1
V
V
2.0
VUVLO
∆VUVLO
Current Limit
MIN TYP MAX UNIT
1.0
US211
US211A
US211B
US211C
US211
VOUT=0V, measured prior to US211A
thermal shutdown
US211B
US211C
0.6
1.1
1.3
1.5
25
0.1
0.5
45
1
10
µA
µA
µA
0.8
1.5
1.7
2.0
0.8
1.0
1.0
1.3
1.1
1.9
2.1
2.4
A
A
A
A
A
A
A
A
80
80
400
110
110
mΩ
mΩ
µs
0.01 1
20 400
µA
Ω
POWER SWITCH
Switch ON Resistance
RDS(ON)
Output Turn-ON Rise Time
OVER CURRENT FLAG
FLAG OFF Current
FLAG Output Resistance
tON(RISE)
FLAG Delay Time
THERMAL SHUTDOWN
Thermal Shutdown Protection
Thermal Shutdown Hysteresis
IOUT= 500mA
IOUT=1.0A
10% ~ 90% of VOUT rising
I FLG(OFF)
V FLG =5V
RFLG
ISINK=1mA
tD
From fault condition to FLG assertion
TSD
∆TSD
UNISONIC TECHNOLOGIES CO., LTD
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US211
US211A/B/C
2
10
130
20
15
ms
°C
°C
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CMOS IC
APPLICATION INFORMATION
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.
Because the MOSFET is bidirectional when on, if VOUT is greater than VIN, current will flow from VOUT to VIN
There is no a parasitic body diode of N-MOSFET between the drain and source compared to a normal MOSFET,.
The US211 can protect damage from reverse current flow if VOUT being externally forced to a higher voltage than VIN
when the output disabled (VEN > 2V).
Enable Input
The switch will be disabled when the EN pin is in a logic low/high condition. During this condition, the internal
circuitry and MOSFET are turned off, reducing the supply current to 0.1μA typical. Floating the EN 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 (GND) to keep the part on.
Soft Start for Hot Plug-In Applications
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.
Fault Flag
The fault flag is an open-drained output of an N-channel MOSFET. The flag drops low to indicate fault conditions:
current limit, thermal shutdown or VOUT < VIN − 1V. In order to reduce energy drain, a large pull-up resistor is required.
100kΩ pull-up resistor is recommended for most applications.
In the case of over current condition, the fault flag is active only if 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.
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CMOS IC
APPLICATION INFORMATION(Cont.)
Current Limiting and Short-Circuit Protection
The current limit circuit protects the MOSFET switch and the hub downstream port from damage. This circuit can
deliver load current up to the current limit threshold of typically 0.8A through the switch of US211, 1.5A for US211A,
1.7A for US211B and 2.0A for US211C. When an enabled switch applies a heavy load or short circuit, a
large-desired transient current occurs which can cause the current limit circuit response. If this current becomes
higher than the current limit threshold, the devices enter constant current mode until thermal shutdown occurs or the
fault is removed.
Thermal Shutdown
The thermal shutdown circuit is used to prevent damage occurs when the die temperature becomes higher than
approximately 130°C. After 20°C of hysteresis, the switch will automatically restart if it enabled. When these devices
are disabled or the fault is removed, the output and FLG signal will continue to cycle on and off.
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CMOS IC
TEST CIRCUIT
RFG
VIN
VIN
FLG
VFLG
S1
UTC
US211/A/B/C
CI
Chip
Enable
CTL
VOUT
GND
A
IOUT
VOUT
CO
RL
IL
Fig.1 Turn-On & Off Response, Flag Response
ISupply
A
VIN
VIN
CIN
FLG
UTC
US211/A/B/C
Chip
Enable
VOUT
EN
VFLG
ILEAK AGE
A
RL
GND
Fig.2 Supply Current
VRDS(ON)
V
IOUT
VOUT
VIN
VIN
CIN
Chip
Enable
UTC
US211/A/B/C
COUT
FLG
EN
GND
Fig.3 On-Resistance
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CMOS IC
TEST CIRCUIT
RFG
VIN
VIN
FLG
VFLG
UTC
US211/A/B/C
CI
CTL
VCTL
GND
VOUT
VOUT
CO
RL
IL
Fig.4 UVLO at Rising & Falling
S2
RFG
VIN
VIN
CI
FLG
VFLG
UTC
US211/A/B/C
CTL
GND
VOUT
VOUT
CO
IOUT
A
S3
RL
IL
Fig.5 Current Limit vs. Input Voltage, Inrush Current Response,
Current Limit Transient Response
Note: Above test circuits reflected the graphs shown on “Typical Operating Characteristics” are as follows:
Fig.1 Turn-On Rising & Falling Time vs. Temperature, Turn-On & Off Response, Flag Response.
Fig.2 Supply Current vs. Input Voltage & Temperature, Switch Off Supply Current vs. Temperature, Turn-Off
Leakage Current vs. Temperature.
Fig.3 On-Resistance vs. Input Voltage & Temperature.
Fig.4 EN Threshold Voltage vs. Input Voltage & Temperature, Flag Delay Time vs. Input Voltage &
Temperature, UVLO Threshold vs. Temperature, UVLO at Rising & Falling.
Fig.5 Current Limit vs. Input Voltage/Temperature, Short Circuit Current Response, Short Circuit Current vs.
Temperature, Inrush Current Response, Soft-start Response, Ramped Load Response, Current Limit
Transient Response, Thermal Shutdown Response.
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CMOS IC
TYPICAL APPLICATION CIRCUIT
Pull-Up Resistor (10K ~ 100K)
RFG
Supply Voltage 5V
10K
VIN
FLG
USB
Controller
Over Current
0.1µF
UTC
US211/A/B/C
1µF
Chip Enable
Flag Transient Filtering
CTL
VBUS
D+
DGND
VOUT
GND
10µF
150µF
Ferrite Beades
Data
Note. A low-ESR 150μF aluminum electrolytic or tantalum between VOUT and GND is strongly recommended to meet
the 330mV maximum droop requirement in the hub VBUS.
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CMOS IC
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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