Datasheet

UNISONIC TECHNOLOGIES CO., LTD
US2076A
Preliminary
CMOS IC
DUAL USB HIGH-SIDE POWER
SWITCH
„
DESCRIPTION
The UTC U2076A is a dual integrated high-side power switch
particularly designed for self-powered and bus-powered Universal
Serial Bus (USB) applications.
The UTC U2076A meets the requirements of the USB. The low
on-resistance of the switch satisfies USB voltage drop requirements.
Fault current is limited to typically 750mA, well below the UL 25VA
safety requirement. Flag outputs are available to indicate fault
conditions to the local USB controller. In addition, soft start can
eliminate the momentary voltage drop which is generated on the
upstream port that may occur when the switch is enabled in
bus-powered applications.
This device has independent functions enable and flag, and an
enable input is compatible with both 3.3V and 5V logic.
The UTC U2076A includes protection circuits. Thermal shutdown
circuit is designed to protect the device from being damaged when
high-current loads exist. UVLO (Under-voltage lockout) is used to keep
the device off unless there is a valid input voltage present.
The UTC U2076A is use in applications, such as USB host and
self-powered hubs, bus-powered hubs, hot plug-in power supplies,
and battery-charger circuits.
„
SOP-8
FEATURES
* MOSFET with Low On-Resistance: 140mΩ max.@5.0V per Channel
* Continuous Load Current: 500mA (MIN.) per Channel
* Off-State Supply Current: 1µA (TYP.)
* Output can be Forced Higher than Input (Off-State)
* Current Limit up to 1.25A (MAX.)
* Input Supply Voltage: 3.0V ~ 5.5V
* On-State Supply Current: 110µA (TYP.)
* Thermal Shutdown Protection Circuit
* UVLO (Undervoltage Lockout): 2.4V (TYP.)
* Open-Drain Fault Flag
* 1ms Turn-On (Soft-Start) and Fast Turn-Off
* Compliant to USB Specifications
* Available with Active-Low Enable
„
ORDERING INFORMATION
Ordering Number
US2076AG-S08-R
Package
SOP-8
www.unisonic.com.tw
Copyright © 2010 Unisonic Technologies Co., Ltd
Packing
Tape Reel
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US2076A
Preliminary
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PIN CONFIGURATION
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PIN DESCRIPTION
PIN NO.
PIN NAME
1, 4
EN (A/B)
2, 3
FLG(A/B)
6
GND
7
IN
5, 8
OUT(A/B)
CMOS IC
DESCRIPTION
Enable (Input): Logic-compatible enable input.
Active – Low; Do Not Float.
Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent, UVLO, and
thermal shutdown.
Ground: Supply return.
Supply Input: Output MOSFET source. Also supplies IC's internal circuitry. Connect to
positive supply.
Switch Output: Output MOSFET drain. Typically connect to switched side of load.
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US2076A
„
Preliminary
CMOS IC
BLOCK DIAGRAM
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US2076A
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Preliminary
CMOS IC
ABSOLUTE MAXIMUM RATING
PARAMETER
SYMBOL
RATINGS
UNIT
Output Current
IOUT
Internally Limited
Fault Flag Current
IFLG
50
mA
Fault Flag Voltage
VFLG
+6.0
V
Supply Voltage
VIN
+6.0
V
Output Voltage
VOUT
+6.0
V
Control Input
VEN
-0.3 ~ 6
V
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.
„
OPERATING RATINGS
PARAMETER
Supply Voltage
Ambient Operating Temperature
„
RATINGS
+3 ~ +5.5
-40 ~ +85
UNIT
V
°C
SYMBOL
θJA
RATINGS
160
UNIT
°C/W
THERMAL DATA
PARAMETER
Junction to Ambient
„
SYMBOL
VIN
TOPR
ELECTRICAL CHARACTERISTICS (VIN=+5V, TA=25°C, unless otherwise specified.)
PARAMETER
Supply Current (Note)
Enable Input Threshold
Enable Input Current
SYMBOL
IS(OFF)
IS(ON)
VIH
VIL
IEN
TEST CONDITIONS
switch off, OUT = open
switch on, OUT = open
low to high transition
high to low transition
VEN = VOH(min) = 2.4V
VEN = VOL(max) = 0.8V
MIN
1.0
Enable Input Capacitance
Switch Resistance
Output Turn-On Delay
Output Turn-On Rise Time
Output Turn-Off Delay
Output Turn-Off Fall Time
Output Leakage Current
Short Circuit Current Limit
Overtemperature Shutdown
Threshold
RON
tON(DLY)
tRISE
tOFF(DLY)
tOFF
IO(LEAK)
ISHORT
OTThreshold
Error Flag Output Resistance
Error Flag Off Current
UVLO Threshold
VUVLO
VIN = 5V
VIN = 3V
RL = 10Ω each output
RL = 10Ω each output
RL = 10Ω each output
RL = 10Ω each output
each output
each output
TJ increasing
TJ decreasing
VIN = 5V, IL=10mA
VIN = 3.3V, IL =10mA
VFLAG = 5V
VIN = increasing
VIN = decreasing
UNISONIC TECHNOLOGIES CO., LTD
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0.5
TYP
25
110
2.4
2.2
0.01
0.01
1
100
140
1
0.5
1
1
0.75
135
125
10
15
0.01
2.5
2.3
MAX
2.5
1
1
20
20
10
1.25
1
UNIT
μA
μA
V
V
μA
μA
pF
mΩ
mΩ
ms
ms
μs
μs
μA
A
°C
°C
Ω
Ω
μA
V
V
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Preliminary
CMOS IC
FUNCTIONAL DESCRIPTION
The UTC US2076A is dual high-side switch with active-low enable inputs. Fault conditions turn off or inhibit
turn-on one or both of the output transistors, controlling by the type of fault, and the FLG pin is pulled to ground by
being activated the open-drain error flag transistors.
Input and Output
IN (input) is the power supply connection to the logic circuitry and the source of the output MOSFET. OUT(output)
is the drain of the output A or B MOSFET.
IN pin (input) is the power supply connection to the logic circuitry and the source of the output MOSFET. OUT pin
(output) is the output MOSFET’s drain. Current flows through the switch from IN pin to OUT pin toward the load in
many applications. All OUT pins must be connected together to the load.
The output MOSFET and driver circuit are also designed to allow the MOSFET drain to be externally forced to a
higher voltage than the source (VOUT > VIN) when the switch is off. This avoids undesirable drain-to-body diode
current flow by connecting the body to the most positive voltage. If VOUT >VIN when switch is enabled, current will
flow from VOUT to VIN.
Thermal Shutdown
Thermal shutdown is designed to prevent this device from being damaged due to excessive power dissipation. It is
used to turn off the output MOSFET if the temperature is higher than135°C, 10°C of hysteresis prevents the switch
from turning on until the die temperature drops to 125°C. Thermal shutdown circuit functions only when the switch is
enabled.
Undervoltage Lockout
UVLO (Undervoltage Lockout) turns off the MOSFET switch and signals the fault flag pin once the input voltage
falls below 2.3V (TYP.) and if the input voltage exceeds 2.5V (TYP.), the switch will be turned on. UVLO detection
functions only when the switch is enabled.
Current Sensing and Limiting
The current limit threshold is fixed internally, allowing a 0.5A minimum current to flow through the output MOSFET.
However, the current limit threshold can prevent the output MOSFET and external load from being damage. A
current sense circuit protects the MOSFET switch’s output current. If output current becomes higher than the current
limit threshold, the output MOSFET switch is turned off and a fault flag is pulled low. The reaction to an overcurrent
is measured with the following scenarios:
Switch Enable into Heavy Load
If a switch is powered-on or enabled into a heavy load or short-circuit, the switch immediately goes into a
constant-current mode, reducing output voltage. The fault flag goes low until the load is reduced or thermal
shutdown occurs.
If the switch is powered on or enabled into a heavy load or short-circuit, the switch enters a constant-current mode
immediately, reducing the output voltage. The fault flag drops low until thermal shutdown occurs or the load is
reduced.
Heavy Load Applied Suddenly to Enabled Switch
When a heavy load is applied, a large-undesired transient current occurs which may damage the switch. Then the
current limit circuit may turn off the switch, folding back into constant-current mode. In that case, the fault flag falls
until the load is reduced.
Fault Flag
Fault flag is an open-drained output of an N-channel MOSFET. It drops low to indicate error conditions as follows:
current limiting, UVLO, or thermal shutdown. The flag output MOSFET is capable of sinking a 10mA load to typically
100mV above ground. Both flag pins may be "wire-NORed" to a common pull-up resistor.
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Preliminary
CMOS IC
APPLICATIONS INFORMATION
Supply filtering
In order to control supply transients, a bypass capacitor is located nearly between IN to GND. 0.1µF ~ 1µF is
suitable (See Figure 1). Without a bypass capacitor, an output short may cause sufficient ringing on the input (from
supply lead inductance) to damage internal control circuitry.
Input transients must not exceed the absolute maximum supply voltage (VIN max = 6V) even for a short duration.
Enable Input
For a clearly defined input, the EN pin must be driven logic high or logic low. Floating the input may cause
unpredictable operation. EN should not be allowed to go negative with respect to GND.
Soft Start
The UTC US2076A is high impedance when off and slowly becomes a low impedance as it turns on. This reduces
inrush current and related voltage drop that results from charging a capacitive load, satisfying the USB voltage drop
requirements, for bus-powered applications as shown in Figure 2.
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Preliminary
CMOS IC
APPLICATIONS INFORMATION (Cont.)
In Figure 3, the soft start circuit is shown, and the soft start circuit can be utilized to meet USB transient regulation
specifications with large load capacitances (CBULK >10µF). The device will provide inrush current limiting for these
applications.
USB
Controller
US2076A
1
VBUS
4.7
µF
USB Hub
ENA
OUTA
2 FLGA
3
FLGB
4
ENB
IN
GND
OUTB
8
USB
Function
7
6
CBULK
USB
Function
5
CBULK
GND
USB Peripheral
Cable
Figure 3. Inrush Current-Limit Application
If an inrush current which is from the connection of a heavy capacitive load, the inrush current may cause the fault
flag to fall for a short duration, while the switch is in a constant-current mode, or charging the capacitance. In that
case, to protect this circuit from damage due to erroneous overcurrent reporting, the fault flag circuit can be in series
with a simple 1ms RC low-pass filter (see Figure 4)
Transient Overcurrent Filter
V
+
UTC
US2076A
10k
USB Controller
10k
OC
0.1µF
1 ENA
2
FLGA
3
FLGB
OUTA
8
IN
7
4 ENB
OUTB
GND 6
5
Figure 4. Transient Filter
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Preliminary
CMOS IC
TYPICAL APPLICATION CIRCUIT
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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