Page 1
SC5826
© 2000 SEMTECH CORP.
HotSwitch™
USB Power Distribution Switch
PRELIMINARY - February 18, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
1
ORDERING INFORMATION
DESCRIPTION
USB power distribution switches are high-side nchannel MOSFET switches with built-in overcurrent
protection and low on-state resistance. The SC5826
switch is designed to meet the USB requirements for
power switching and maintenance-free fault protection
for self-powered & bus-powered hub applications. The
SC5826 features low on-state resistance to meet the
USB requirement for voltage drop and regulation. The
switch is controlled by an enable input that is
compatible with 3V and 5V logic. The enable input is
available with an active high or active low input for
maximum design flexibility. The device provides short
circuit current limiting at a value of less than 1.6A, well
below the USB limit of 5A. During an overcurrent
condition the device provides a fault notification to
signal the USB controller. An integrated thermal
protection circuit automatically shuts the switch off
when the junction temperature reaches its thermal
limit. The switch remains off until the junction
temperature drops approximately 10°C. The switch will
continue to cycle on and off until the fault is removed.
Inrush current limiting prevents the voltage drop on an
upstream port when the switch is enabled. An
undervoltage lockout circuit guarantees the switch is
initially off during start-up.
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
Note:
(1) Add suffix ‘TR’ for tape and reel.
DEVICE
(1)
ENABLE PACKAGE
SC5826-1CS Active High SO-8
SC5826-2CS Active Low SO-8
FEATURES
•
Designed to meet
USB specification 1.1
power
management requirements
•
500mA continuous load current
•
High-side MOSFET switch with low R
DS(ON)
•
Short-circuit current protection
•
Internal thermal shutdown
•
Undervoltage lockout
•
Logic overcurrent output
•
Soft start circuit with slow turn-on time
APPLICATIONS
•
Universal Serial Bus (USB) power management
•
Self-powered or bus-powered USB hubs
•
Root hubs in desktop PCs & servers
•
Notebook PCs
•
Peripherals
BLOCK DIAGRAM
PIN CONFIGURATION
Top View
(8-Pin SOIC)
Page 2
SC5826
© 2000 SEMTECH CORP.
HotSwitch™
USB Power Distribution Switch
PRELIMINARY - February 18, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
2
Parameter Symbol Maximum Units
Input Voltage Range V
IN
-0.3 to +7 V
Output Voltage Range` V
OUT
-0.3 to +7 V
Enable Input V
EN
-0.3 to +7 V
Continuous Output Current I
O
Internally Limited mA
Operating Ambient Temperature Range T
A
-40 to +85 °C
Operating Junction Temperature Range T
J
-40 to +125 °C
Storage Temperature Range T
STG
-65 to +150 °C
Lead Temperature (Soldering) 10 seconds T
L
300 °C
ABSOLUTE MAXIMUM RATINGS
PIN DESCRIPTION
Pin # Pin Name Pin Function
1, 4 ENA/ENB Enable input: TTL compatible switch enable input.
2, 3 FLGA/FLGB Error flag output: FLG is asserted active low during fault condition.
6 GND Ground.
7 IN Input voltage: Output MOSFET Drain. Connect to supply voltage.
5, 8 OUTA/OUTB Power switch output: Output MOSFET Source. Connect to switched side of load.
PIN CONFIGURATION
Top View
(8-Pin SOIC)
Page 3
SC5826
© 2000 SEMTECH CORP.
HotSwitch™
USB Power Distribution Switch
PRELIMINARY - February 18, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
3
ELECTRICAL CHARACTERISTICS
(1)(2)
Unless specified: TA = 25°C, VIN = 5V, IOA/IOB = 500mA (Switches ON).
Parameter Symbol Conditions Min Typ Max Units
Power Switch
On Resistance r
ON
4.25V ≤ VIN ≤ 5.50V
100 140
m
Ω
Output Leakage Current I
L(OFF)
VO = 5.5V, Switches OFF 1 µA
Output Turn On Rise Time t
R
CO = 1µF, RO = 10
Ω
1ms
Output Turn Off Fall Time t
F
CO = 1µF, RO = 10
Ω
0.1 1 ms
Enable Input
High Level Input Voltage V
EN(HI)
4.25V ≤ VIN ≤ 5.50V
2.4 V
Low Level Input Voltage V
EN(LO)
4.25V ≤ VIN ≤ 5.50V
0.8 V
Input Current I
EN
EN = VIN, OUTA/B = OPEN 0 1 µA
EN = 0V, I
OA/IOB
= 0mA, OUTA/B = OPEN 0 1
Output Turn On Delay t
D(ON)
0.25 ms
Output Turn Off Delay t
D(OFF)
25 50 µs
Current Limit
Short Circuit Current Limit I
OS
VOA/VOB = GND, Switches ON 0.65 0.90 1.60 A
Supply Current
Outputs Off I
IN(OFF)
Switches OFF 0.02 1 µA
Outputs On I
IN(ON)
IOA/IOB = 0mA 130 200 µA
Undervoltage Lockout
UVLO Threshold V
UVLO
2.2 2.7 V
Hysteresis V
HYST
90 mV
Error Flag
Output Resistance r
FLG
I
FLG
= 10mA, VOA/VOB = GND, Switches ON 10 50
Ω
Leakage Current (Off) I
FLG
V
FLG
= 5.0V, Switches OFF 0.01 1 µA
Over Temperature Protection
High Trip Level T
HI
160 °C
Hysteresis T
HYST
10 °C
NOTE:
(1) For SC5826-1, Switch OFF is V
EN
≤ 0.8V and Switch ON is VEN ≥ 2.4V (“Active High”).
For SC5826-2, Switch ON is V
EN
≤ 0.8V and Switch OFF is VEN ≥ 2.4V (“Active Low”).
For testing purposes EN will be 0V or V
IN
as applicable, unless otherwise specified.
(2) This device is ESD sensitive. Use of standard ESD handling precautions is required.
Page 4
SC5826
© 2000 SEMTECH CORP.
HotSwitch™
USB Power Distribution Switch
PRELIMINARY - February 18, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
4
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-50 -25 0 25 50 75 100 125 150
T
J
(°C)
I
OS
(A)
VIN = 5V
2.000
2.100
2.200
2.300
2.400
2.500
2.600
2.700
2.800
2.900
3.000
-50 -25 0 25 50 75 100 125 150
T
J
(°C)
V
UVLO
(V)
VIN Rising
VIN Falling
0
25
50
75
100
125
150
175
200
-50 -25 0 25 50 75 100 125 150
T
J
(°C)
I
IN(ON)
(µA)
VIN = 5V
TYPICAL CHARACTERISTICS
Supply Current (Outputs On)
vs. Junction Temperature
Short Circuit Output Current
vs. Junction Temperature
UVLO Threshold vs.
Junction Temperature
50
60
70
80
90
100
110
120
130
140
150
-50 -25 0 25 50 75 100 125 150
T
J
(°C)
r
ON
(m
Ω
ΩΩ
Ω
)
IO = 0.5A
V
IN
= 4.25V
V
IN
= 5.5V
On Resistance vs. Junction Temperature
vs. Input Voltage
Page 5
SC5826
© 2000 SEMTECH CORP.
HotSwitch™
USB Power Distribution Switch
PRELIMINARY - February 18, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
5
DETAILED DESCRIPTION
The SC5826 HotSwitch™ is a dual port, high-side
switch optimized for power control & distribution in Universal Serial Bus (USB) applications. It features an nchannel power MOSFET with a low on-state resistance
for meeting USB voltage regulation requirements. It
available with active high (SC5826-1) or active low
(SC5826-2) inputs.
In/Out
The input is the supply voltage connection to the drain
of the power switch MOSFET. The output is connected to the source of the MOSFET. Under normal
operating conditions when the power switch is enabled,
current flows from the input to the output towards the
load. The power switch is designed to sustain a minimum load current of 500mA in accordance with USB
specifications.
Charge Pump
An internal charge pump powers the MOSFET gate
drive circuit and provides the necessary voltage to pull
the gate above the source.
Control Logic
The gate drive circuit controls the gate voltage of the
MOSFET power switch. The gate drive circuit also
controls the rise & fall times of the power switch output
voltage. The typical “soft start” or output voltage rise
time is 1ms.
Enable Input
A logic signal at the enable (EN) pin activates the
power MOSFET switch. A logic 1 (SC5826-1) or logic
0 (SC5826-2) will bias the charge pump, gate drive,
and control circuitry turning on the power switch. A
logic signal of opposite polarity turns off the switch. If
both outputs are off, the device powers down. The enable input is compatible with 3V & 5V logic levels.
Error Flag
The error flag (FLG) output is an n-channel, open drain
MOSFET. The FLG pin is an active low during short
circuit, undervoltage, or thermal shutdown conditions.
The output remains low until the fault condition is removed.
Thermal Sense
An internal thermal shutdown circuit turns off the power
switch output MOSFET when the die junction temperature exceeds 160°C. The output FLG pin is asserted
to a logic low signaling a fault condition. A built in hys-
teresis prevents the switch from turning on until the die
temperature has cooled approximately 10°C. The
switch will continue to cycle on and off until the fault
condition is removed. The thermal sense circuit functions only when the switch is enabled.
Undervoltage Lockout
An undervoltage lockout circuit monitors the input voltage and prevents the power switch MOSFET from
turning on until the input voltage (IN) exceeds 2.5V
(typical). If the input voltage falls 90mV (typical) below
that point after the switch has been turned on, the undervoltage lockout turns off the power switch output
MOSFET and asserts the FLG output to logic low. The
undervoltage lockout functions only when the switch is
enabled.
Page 6
SC5826
© 2000 SEMTECH CORP.
HotSwitch™
USB Power Distribution Switch
PRELIMINARY - February 18, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
6
TYPICAL APPLICATIONS
Figure 1 - Self-powered hub with individual port power management
Self-powered hub, indidual port power
management:
A self-powered hub must supply a continuous 500mA
of current to each downstream port. Since an internal
power supply is used to supply the power, self-powered
hubs are required to implement overcurrent protection
for safety. The self-powered hub must also have a
method to detect and report fault conditions to the USB
controller. The circuit below utilizes the SC5826 to provide individual port overcurrent protection & power
switching for maximum port protection. Under fault
conditions, the SC5826 provides the short-circuit current limiting function and has a fault flag logic output for
notifying the hub controller. The USB hub can use the
SC5826 to remove power from the faulty port, allowing
the other ports to operate normally.
Since USB is a hot insertion and removal system, USB
ports are subject to electrostatic discharge (ESD). The
SRDA05-4 provides ESD protection on the downstream data and power lines. Each device will protect
two USB ports. With proper layout the port is hardened to greater than 15kV, meeting the requirements
of IEC 1000-4-2. On the upstream port, the LCDA05
provides ESD protection to the above levels for one
line pair. The SC5203 (or SC5205) LDO regulator is
used to power the hub controller from the upstream
bus.
Page 7
SC5826
© 2000 SEMTECH CORP.
HotSwitch™
USB Power Distribution Switch
PRELIMINARY - February 18, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
7
TYPICAL APPLICATIONS
Figure 2 - Bus-powered hub with ganged port power management
Bus-powered hub, ganged port power
management:
A bus-powered hub distributes power and data from an
input port to downstream ports. It must supply a continuous 100mA of current to each downstream port. A
bus-powered hub must be able to switch power to
downstream ports to prevent illegal device hook-up.
Inrush current limiting is also required to prevent power
supply drooping. The circuit below utilizes the SC5826
to provide ganged port power switching, inrush current
limiting and overcurrent protection for maximum port
protection. In a ganged switch configuration, all ports
are switched simultaneously. Under fault conditions,
the USB controller will remove power to all of the
ganged ports. For individual port management, an additional SC5826 may be used.
Since USB is a hot insertion and removal system, USB
ports are subject to electrostatic discharge (ESD). The
SRDA05-4 provides ESD protection on the downstream data and power lines. Each device will protect
two USB ports. With proper layout the port is hardened to greater than 15kV, meeting the requirements
of IEC 1000-4-2. On the upstream port, the LCDA05
provides ESD protection to the above levels for one
line pair. The SC5203 (or SC5205) LDO regulator is
used to power the hub controller from the upstream
bus.
Page 8
SC5826
© 2000 SEMTECH CORP.
HotSwitch™
USB Power Distribution Switch
PRELIMINARY - February 18, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
8
OUTLINE DRAWING - SO-8
JEDEC
REF: MS-012AA
LAND PATTERN - SO-8
ECN00-886
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