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BL2556
1A USB Load Current Switch with 5V Output Voltage Limit
DESCRIPTION
FEATURES
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The BL2556 is 1A USB Load Current Switch with
output voltage limit at 5V, designed for high-side
load switching applications. The internal currentlimiting circuit protects the input supply against
large output short circuit current which may
cause the supply to fall out of regulation.
The output voltage limiting function protects the
output over voltage when BL2556’s Vin sees
voltage surge.
The current limit is fixed around 1.4A which allow
1A USB application. The quiescent supply current
is typically 15μA, making the device ideal for
portable battery-operated equipment. In
shutdown mode, the supply current decreases to
less than 0.1μA.
Additional features include thermal shutdown
and short-circuit protection and current fold-back.
Stand input voltage as high as 10V
Output voltage limiting at 5V
Controlled turn-on
Fixed current limit large than 1A
0.25ohm on resistance
Extremely low quiescent current at 15uA typ.
Logic Control Shutdown (IQ<1uA)
Thermal shutdown
Short-circuit protection
Short-circuit current fold-back
SOT23-5 package
APPLICATIONS
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Portable Devices
MID, MP4…
Set top boxes
Notebook and PC mother board
USB supplied Devices
The part is available in a tiny SOT23-5 package.
TYPICAL APPLICATION
PIN OUT & MARKING
CE
VIN
1uF
CE
Vout
4
Vin
Vout
5
Vin
LC4001
BL2556
Gnd
4.7uF
P0YW |
VOUT GND
3
2
1
CE
NC
SOT23-5
P0: product code;
YW: data code
ORDERING INFORMATION
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1
BL2556
PART No.
BL2556CB5TR
PACKAGE
SOT23-5
Tape&Reel
3000/Reel
ABSOLUTE MAXIMUM RATING
Parameter
Value
Max Input Voltage
Max Operating Junction Temperature(Tj)
Ambient Temperature(Ta)
Maximum Power Dissipation
SOT23-5
Storage Temperature(Ts)
Lead Temperature & Time
ESD (HBM)
10V
125C
-40C – 85C
0.35W
-40C - 150C
260C, 10S
>2000V
Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect
device reliability.
RECOMMENDED WORK CONDITIONS
Parameter
Value
Input Voltage Range
Operating Junction Temperature(Tj)
Max. 5.5V
-20C –125C
ELECTRICAL CHARACTERISTICS
(Vin=5V, TA=25C)
Symbol
Parameter
Vin
Input Voltage Range
Iq
Quiescent Current
Rdson
Switch Rdson
Ilimit
fixed current limit
Vovp
Output voltage limiting
Vh_on
ON Input High Voltage
Vl_on
ON Input Low Voltage
Tsd
Conditions
Typ
1.5
Active, Vfb=0.65, No Switching
15
Shutdown
Iout=500mA
250
Max
Unit
5.5
V
50
uA
1
uA
350
mohm
1.5
Vin=6V
4.9
5
A
5.1
1.5
165
2
V
V
0.3
Thermal shutdown Temp.
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Min
V
o
C
BL2556
PIN DESCRIPTION
PIN #
1
2
3
4
5
NAME
Vout
GND
NC
CE
Vin
DESCRIPTION
Switch Output, the output of power switch
Ground
Not connected
Control input, enable pin, active high
Supply input voltage
ELECTRICAL PERFORMANCE
Tested under TA=25C, Cin=1uF, Cout=1uF, unless otherwise specified
BLOCK DIAGRAM
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3
BL2556
DETAILED DESCRIPTION
Operation
The BL2556 is a current limited switch that protects
systems and loads which can be damaged or
disrupted by the application of high currents. The
core of each device is a 0.25Ω P-channel MOSFET
and a controller capable of functioning over a wide
input operating range up to 10V. The chip protects
against system malfunctions through current
limiting, undervoltage lockout and thermal
shutdown. The current limit is set around 1.5A and
it offers an unique function to limit output voltage
at 5V.
On/Off control
The CE pin controls the state of the switch. When
CE is high, the switch is in the ON state. Activating
CE continuously holds the switch in the on state
so long as there is no fault. An under voltage on
VIN or a junction temperature in excess of 165°C
overrides the CE control to turn off the switch.
Output Over-Voltage Limiting
BL2556 provides an unique output voltage
limiting function, to protect the load which
follows it. When BL2556 find out input voltage
higher than 5.3V, it will limit the output voltage,
so the output will not exceed standard USB
voltage even when input comes across a voltage
surge.
Current limiting
The current limit is internally set around 1.5A to
ensure a 1A application.
Thermal and Short Circuit Protection
BL2556 will shut off its output when its
temperature higher than 165°C (typical value).
And it has unique short circuit fold-back function
to keep itself cold when output is shorted to GND.
PACKAGE OUTLINE
Package
SOT23-5
Devices per reel
Package specification:
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4
3000
Unit
mm