Datasheet

UNISONIC TECHNOLOGIES CO., LTD
US1528
Preliminary
CMOS IC
USB HIGH-SIDE POWER SWITCH
ADVANCE INFORMATION
„
DESCRIPTION
The UTC US1528 is an integrated high-side power switch. It is
designed particularly for self-powered and bus-powered USB (Universal
serial bus) applications.
The UTC US1528 meets the requirements of the USB. The low
on-resistance of the switch meets USB voltage drop requirements.
When the output load becomes higher than the current-limit threshold,
the UTC US1528 switches into constant- current mode and limits the
output current at 1.4A (TYP).
An open-drain flag, playing a role as the MOSFET output, is included
to indicate error conditions to the local USB controller. A thermal
shutdown circuit protects this device from catastrophic switch failure,
which is caused by increasing power dissipation when continuous heavy
loads or short circuit occurs. In addition, soft start is used to avoid the
momentary voltage drop generated on the upstream port that may occur
when the switch is enabled in bus-powered applications. A UVLO
(under-voltage lockout) circuit is used to keep the device off unless there
is a valid input voltage present, and an enable input that is compatible
with both 3.3V and 5V logic.
The UTC US1528 can be used for high-side power protection switch,
USB power management, USB host and self-powered hubs, hot plug-in
power supplies and battery-charger circuits.
„
FEATURES
* Open-Drain Fault Flag
* Low on-Resistance MOSFET: Typical 110mΩ(at 5.0V)
* Operating Voltage Varying From 3.0V to 5.5V
* Output can be Forced Higher than Input when Operating in Off State.
* Slow Turn-On (Soft-Start) and Fast Turn-Off
* On-State Supply Current: 100 µA (TYP)
* Standby Supply Current: 1µA (TYP)
* Current Limit: 1.4A (TYP)
* Thermal Shutdown Protection Circuit
* UVLO (Under-Voltage Lockout): 2.4V (TYP)
* Logic Level Enable Pin, Available with Active-High/Low Version
„
ORDERING INFORMATION
Ordering Number
US1528XG-S08-R
Package
SOP-8
www.unisonic.com.tw
Copyright © 2010 Unisonic Technologies Co., Ltd
Packing
Tape Reel
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US1528
Preliminary
„
PIN CONFIGURATION
„
PIN DESCRIPTION
PIN NO.
1
PIN NAME
GND
2, 3
IN
4
EN
EN
5
FLG
6, 7, 8
OUT
CMOS IC
DESCRIPTION
Ground.
Input Supply: Output MOSFET source, which also supplies IC's internal circuitry.
Connect to positive supply.
Active-High switch enable input. A logic low turns on the switch.
Active-Low switch enable input. A logic low turns on the switch.
Open-Drain Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent,
thermal shutdown and UVLO.
Switch Output: Output MOSFET drain. Typically connect to switched side of load.
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US1528
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Preliminary
CMOS IC
BLOCK DIAGRAM
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Preliminary
CMOS IC
ABSOLUTE MAXIMUM RATING
PARAMETER
SYMBOL
RATINGS
UNIT
Supply Voltage
VIN
+6.0
V
Fault Flag Voltage
VFLG
+6.0
V
Fault Flag Current
IFLG
50
mA
Output Voltage
VOUT
+6.0
V
Output Current
IOUT
Internally Limited
Enable Input
VEN
-0.3~6
V
Storage Temperature
TSTG
-65~+150
°C
Notes: 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)
PARAMETER
SYMBOL
IS(OFF)
IS(ON)
VIH
VIL
IEN(H)
IEN(L)
TEST CONDITIONS
switch off, OUT = open
switch on, OUT = open
low to high transition
high to low transition(Note)
VEN= VOH(min)= 2.5V
VEN= VOL(max)= 1.0V
UNIT
µA
IN Supply Current (Note)
µA
V
EN/ EN Enable Threshold
0.8
V
0.01
1
µA
EN/ EN Input Current
0.01
1
µA
1
pF
EN/ EN Input Capacitance
VIN= 5V, IOUT=500mA
110
140
mΩ
Switch Resistance
RON
130
180
mΩ
VIN= 3.3V, IOUT=500mA
OUT Turn-On Delay
tON
RL=10Ω
0.03
ms
OUT Turn-On Rise Time
tR
RL=10Ω, CL=100µF
0.5
ms
OUT Turn-Off Delay
tOFF
RL=10Ω
1
20
µs
OUT Turn-Off Fall Time
tF
RL=10Ω
1
20
µs
OUT Leakage Current
IO(LEAK)
1
10
µA
Short Circuit Current Limit
ISHORT Enable into load
1.0
1.4
2.0
A
Circuit Limit Threshold
Ramped load applied to enabled output
2.0
2.7
3.5
A
Overtemperature Shutdown
TJ increasing
135
°C
OTThreshold
Threshold
125
°C
TJ decreasing
VIN=5V, IL=10mA
10
25
Ω
FLG Output Resistance
RON(FLAG)
VIN=3.3V, IL=10mA
15
40
Ω
FLG Off Current
IFLAG
VFLAG=5V
0.01
1
µA
VIN=increasing
2.5
V
UVLO Threshold
VUVLO
VIN=decreasing
2.3
V
Note:For the UTC US1528, off is ≥ 2.5V and on is ≤ 0.8V. The enable input, EN has approximately 200mV of hysteresis.
UNISONIC TECHNOLOGIES CO., LTD
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MIN
TYP
1
100
MAX
5
160
2.5
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Preliminary
CMOS IC
FUNCTIONAL DESCRIPTION
The UTC US1528 is high-side single channel power switch; it has an enable input in active low. Fault
conditions turn off or inhibit turn-on of the output transistors.
Input and Output
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 driving 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 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. The reaction to an overcurrent is measured with
the following scenarios:
Switch Enabled into Heavy Load
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.
Heavy Load Applied 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.
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.
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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.
EN/ EN , The Active-High/Low Enable Input
For a clearly defined input, the EN/ EN pin, with 0.2V hysteresis, must be driven logic high or logic low. Floating
the input may cause unpredictable operation. EN/ EN should not be allowed to go negative with respect to GND.
Soft Start
The UTC US1528 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.
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.
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Preliminary
CMOS IC
TYPICAL APPLICATION CIRCUIT
VCC
5.0V
10k
Upstream
VBUS
100mA max.
3.3V LDO
VBUS
D+
IN
3.3V USB Controller
OUT
VIN
ON/OFF
1μF
OC
GND
1μF
D-
100k
UTC
US1528L
EN
Ferrite
Beads V
BUS
OUT
FLG
GND
+
D+
150μF
D-
IN
GND
0.1μF
USB
Port1
GND
Ferrite
Beads
GND
Data
Data
Single-Port Self-Powered USB Hub Application
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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