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SC2041IS.TR

Datasheet SC2041IS.TR Datasheet (Semtech Corporation)

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HotSwitch™ USB Power Distribution Switch With Shutdown
SC2041
July 18, 2000
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DESCRIPTION
FEATURES
•= Designed to meet USB specification revisions 1.1
and 2.0 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
•= Open drain fault output
•= Soft start circuit with slow turn-on time
•= Wide supply voltage range: 2.8V to 5.5V
•= 2.5kV ESD rating (Human Body Model)
•= Full industrial temperature range
APPLICATIONS
•= Universal Serial Bus (USB) power management
•= Self-powered or bus-powered USB hubs
•= Root hubs in desktop PCs & servers
•= Notebook PCs
•= Peripherals
ORDERING INFORMATION
DEVICE
SC2041IS.TR SO-8
(1)
PACKAGE
TYPICAL APPLICATION CIRCUIT
VBUS IN
Shutdown Signal From USB Controller
R1
Flag Output To USB Controller
Note: (1) Only available in tape and reel packaging. A reel contains 2500 devices.
U1 SC2041
C1
0.1uF
1
GND
2
IN
3
IN
4 5
SHDN FLG
OUT OUT OUT
8 7 6
C2
0.1uF
C3 22uF
VBUS OUT
© 2000 SEMTECH CORP.
1
652 MITCHELL ROAD NEWBURY PARK CA 91320
HotSwitch™ USB Power Distribution
SC2041
Switch With Shutdown
July 18, 2000
ABSOLUTE MAXIMUM RATINGS
Parameter Symbol Maximum Units
Input Voltage Range V Output Voltage Range V Shutdown Input V Flag Output V Continuous Output Current I Thermal Impedance Junction to Ambient Thermal Impedance Junction to Case
θ θ
Operating Ambient Temperature Range T Operating Junction Temperature Range T Storage Temperature Range T Lead Temperature (Soldering, 10 seconds) T
IN
OUT
EN
FLG
O
JA
JC
A
J
STG
L
-0.3 to +7 V
-0.3 to +7 V
-0.3 to +7 V
-0.3 to (V
+ 0.3) V
IN
Internally Limited mA
130 °C/W
47 °C/W
-40 to +85 °C
-40 to +125 °C
-65 to +150 °C 300 °C
ESD Rating (Human Body Model) ESD 2.5 kV
ELECTRICAL CHARACTERISTICS
Unless specified: TA = 25°C, V
Parameter Symbol Conditions M in Typ Max Units IN
Supply Voltage Range V Supply Current I
= 5V, V
IN
SHDN
= GND, I
IN
Q
= 500mA. Values in bold apply over the full operating temperature range.
OUT
2.8 5.5
VIN = 3.3V 85 130 µA
V
200
Power Switch
On Resistance r
OUT
Output Leakage Current I
L(OFF)
Output Turn On Delay t Output Turn On Rise Time t Output Turn Off Delay t
d(OFF)
Output Turn Off Fall Time t
© 2000 SEMTECH CORP.
ON
d(ON)
r
f
V
SHDN
VIN = V
R R R R
V
= 5.0V 100 130 µA
IN
200
= VIN = 5.5V (OFF) 0.1
VIN = 3.3V 85 105
150
V
= 5.0V 80 100
IN
135
SHDN
= 10Ω, C
OUT
= 10Ω, C
OUT
= 10Ω, C
OUT
= 10Ω, C
OUT
= 5.5V, V
= GND 0.01
OUT
= 1µF
OUT
= 1µF
OUT
= 1µF
OUT
= 1µF
OUT
0.9 ms
1.7 ms 20 µs 25 µs
652 MITCHELL ROAD NEWBURY PARK CA 91320
1
µA
mΩ
1
µA
2
HotSwitch™ USB Power Distribution
SC2041
Switch With Shutdown
July 18, 2000
ELECTRICAL CHARACTERISTICS (Cont.)
Unless specified: TA = 25°C, V
Parameter Symbol Conditions M in Typ Max Units Current Limit
Short Circuit Current Limit I Current Limit Trip Threshold I
SHDN
= 5V, V
IN
SHDN
= GND, I
CL
TH(CL)
= 500mA. Values in bold apply over the full operating temperature range.
OUT
V
= GND
OUT
0.60
0.85
1.5 A
1.10
A
High Level Input Voltage V Low Level Input Voltage V Input Current I
IH
IL
SHDN
V
SHDN
2.8V ≤ VIN ≤ 5.50V
2.8V ≤ VIN ≤ 5.50V
V
= VIN = 5.5V, V
SHDN
= GND, I
= 0mA, V
OUT
= OPEN
OUT
OUT
= OPEN
2.4
0.8 1 1
Undervoltage Lockout
UVLO Threshold V
UVLO
VIN rising 2.7 V
falling 2.4 V
V
IN
FLG
Output Resistance r Leakage Current (OFF) I
FLG
FLG
I
= 10mA, VO = GND, Switch ON
FLG
V
= 5.0V, Switch OFF
FLG
50
1
Over Temperature Protection
High Trip Level T Hysteresis T
HI
HYST
150 °C
20 °C
TIMING DIAGRAM: OUTPUT TURN ON/OFF DELAY TIMES AND RISE/FALL TIMES
V V
µA
Ω
µA
© 2000 SEMTECH CORP.
3
652 MITCHELL ROAD NEWBURY PARK CA 91320
July 18, 2000
BLOCK DIAGRAM
HotSwitch™ USB Power Distribution Switch With Shutdown
SC2041
PIN CONFIGURATION
Top View
(8-Pin SOIC)
PIN DESCRIPTION
Pin # Pin Name Pin Function
1 GND Ground.
2, 3 IN Input voltage: drain of N-channel power MOSFET. Connect to supply voltage.
4 SHDN Shutdown input: TTL compatible. N-channel power MOSFET is turned on when this
pin is pulled low.
5 FLG Error flag output: FLG is asserted active low during a fault condition (overcurrent, input
undervoltage or thermal shutdown).
6, 7,8 OUT Power switch output: source of N-channel power MOSFET. Connect to load.
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
4
July 18, 2000
TYPICAL CHARACTERISTICS
HotSwitch™ USB Power Distribution Switch With Shutdown
SC2041
On-State Quiescent Current vs. Junction
Temperature vs. Input Voltage
120
100
80
(µA)
60
Q(ON)
I
40
20
0
-50 -25 0 25 50 75 100 125
I
OUT
V
SHDN
V
V
V
= 500mA
= GND
= 5.0V
IN
= 3.3V
IN
= 3.0V
IN
T
(°C)
J
Off-State Quiescent Current vs. Input
Voltage vs. Junction Temperature
300
250
200
(nA)
150
Q(OFF)
I
100
50
V
= V
SHDN
IN
0
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
(V)
IN
T
T
TA = 25°C
= 125°C
A
= -40°C
A
On-State Quiescent Current
vs. Input Voltage
120
TJ = 25°C I
= 500mA
OUT
100
V
= GND
SHDN
80
(µA)
60
Q(ON)
I
40
20
0
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
(V)
IN
Power Switch On Resistance vs. Junction
Temperature vs. Input Voltage
135
V
= GND
SHDN
I
= 500mA
OUT
125
115
105
)
Ω
Ω
Ω
Ω
95
(m
ON
r
85
75
65
55
-50 -25 0 25 50 75 100 125
T
(°C)
J
Top to bottom: V
= 3.0V
IN
V
= 3.3V
IN
V
= 5.0V
IN
Power Switch On Resistance vs. Input
Voltage vs. Junction Temperature
135
125
115
105
)
Ω
Ω
Ω
Ω
95
(m
ON
r
85
75
65
55
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
SHDN
I
OUT
= GND
= 500mA
V
(V)
IN
© 2000 SEMTECH CORP.
TJ = 125°C
T
= 25°C
J
= -40°C
T
J
Output Turn-On Rise Time vs. Input
Voltage vs Junction Temperature
2.5
2.0
1.5
(ms)
r
t
1.0
C
= 1µF
OUT
0.5 = 6.6Ω (VIN = 2.8V and 3.3V)
R
OUT
= 10Ω (VIN = 5V and 5.5V)
R
OUT
0.0
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
(V)
IN
TJ = 125°C
= 25°C
T
J
T
= -40°C
J
5
652 MITCHELL ROAD NEWBURY PARK CA 91320
HotSwitch™ USB Power Distribution Switch With Shutdown
July 18, 2000
TYPICAL CHARACTERISTICS (Cont.)
SC2041
Short Circuit Current Limit vs. Input
Voltage vs. Junction Temperature
0.95
0.90
0.85
0.80
(A)
CL
I
0.75
0.70
0.65
0.60
= V
V
SHDN
IN
V
= GND
OUT
Top to bottom:
= -40°C
T
J
T
= 25°C
J
T
= 125°C
J
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
(V)
IN
Current Limit Trip Threshold vs. Junction
Temperature vs. Input Voltage
1.6
1.5
1.4
(A)
1.3
TH(CL)
I
1.2
1.1
V V
SHDN OUT
= V
= GND
IN
1.0
-50 -25 0 25 50 75 100 125
T
(°C)
J
VIN = 5.0V
V
V
= 3.3V
IN
= 3.0V
IN
Short Circuit Current Limit vs. Junction
Temperature vs. Input Voltage
0.90
0.85
0.80
(A)
0.75
CL
I
0.70
0.65
V
= V
SHDN
IN
V
= GND
OUT
0.60
-50 -25 0 25 50 75 100 125
T
(°C)
J
Shutdown Threshold vs. Input Voltage
vs. Junction Temperature
2.00
1.75
1.50
1.25
(V)
1.00
TH(SHDN)
V
0.75
0.50
0.25
0.00
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
(V)
IN
Top to bottom:
= -40°C
T
J
T
= 25°C
J
T
= 125°C
J
V
V
V
= 5.0V
IN
= 3.3V
IN
= 3.0V
IN
Error Flag Output Resistance vs. Input
Voltage vs. Junction Temperature
40
35
30
25
)
Ω
Ω
Ω
Ω
(
20
FLG
r
15
10
I
= 10mA
FLG
V
= GND
OUT
5
Switch ON
Top to bottom:
= 125°C
T
J
T
= 25°C
J
T
= -40°C
J
0
2.53.03.54.04.55.05.5
V
(V)
IN
© 2000 SEMTECH CORP.
Undervoltage Lockout vs.
Junction Temperature
2.80
2.75
2.70
2.65
(V)
2.60
UVLO
V
2.55
2.50
2.45
2.40
-50 -25 0 25 50 75 100 125
T
(°C)
J
VIN rising
V
falling
IN
6
652 MITCHELL ROAD NEWBURY PARK CA 91320
HotSwitch™ USB Power Distribution Switch With Shutdown
July 18, 2000
TYPICAL CHARACTERISTICS (Cont.)
SC2041
Figure 1: Output Turn On Delay and Rise Time with
0.1µF Output Capacitor and No Load
Top Trace: V Bottom Trace: V
SHDN
, 5V/div.
, 2V/div.
OUT
Timebase: 1ms/div.
= 5V, R
V
IN
= open, C
OUT
= 0.1µF
OUT
Figure 2: Output Turn On Delay and Rise Time with 1µF Output Capacitor and 10ΩΩΩΩ Load
Top Trace: V Bottom Trace: V
SHDN
, 5V/div.
, 2V/div.
OUT
Timebase: 1ms/div.
= 5V, R
V
IN
= 10Ω, C
OUT
OUT
= 1µF
Figure 3: Output Turn Off Delay and Fall Time with 1µF Output Capacitor and 10ΩΩΩΩ Load
Top Trace: V Bottom Trace: I
, 5V/div.
OUT
OUT
, 0.5A/div.
Timebase: 100ms/div.
= 5V, R
V
IN
ramping from open to 1.1Ω, C
OUT
= 22µF
OUT
Figure 4: Current Limit and Trip Threshold With Ramped Load on Enabled Device
Top Trace: V Bottom Trace: I
, 5V/div.
OUT
OUT
, 0.5A/div.
Timebase: 100ms/div.
= 5V, R
V
IN
ramping from open to 1.1Ω, C
OUT
= 22µF
OUT
© 2000 SEMTECH CORP.
7
652 MITCHELL ROAD NEWBURY PARK CA 91320
HotSwitch™ USB Power Distribution Switch With Shutdown
July 18, 2000
TYPICAL CHARACTERISTICS (Cont.)
SC2041
Figure 5: Current Limit and Trip Threshold With Ramped Load on Enabled Device
Top Trace: V Bottom Trace: I
, 5V/div.
FLG
OUT
, 0.5A/div.
Timebase: 100ms/div.
= 5V, R
V
IN
ramping from open to 1.1Ω, C
OUT
= 22µF
OUT
Figure 6: Short Circuit Current, Device Enabled Into Short
Top Trace: V Bottom Trace: I
SHDN
OUT
, 5V/div.
, 0.2A/div.
Timebase: 1ms/div.
= 5V, R
V
IN
OUT
= 0Ω
Figure 7: Short Circuit Current, Shor t Applied to Enabled Device
Top Trace: V Bottom Trace: I
, 5V/div.
FLG
OUT
, 5A/div.
Timebase: 250µs/div.
= 5V, R
V
IN
= 0Ω, C
OUT
= 22µF
OUT
Note initial output current spike from output capacitor discharge
Figure 8: Current Limit, 1.1ΩΩΩΩ Load Applied to Enabled Device
Top Trace: V Bottom Trace: I
, 5V/div.
FLG
OUT
, 1A/div.
Timebase: 250µs/div.
= 5V, R
V
IN
= 1.1Ω, C
OUT
OUT
= 1µF
© 2000 SEMTECH CORP.
8
652 MITCHELL ROAD NEWBURY PARK CA 91320
HotSwitch™ USB Power Distribution Switch With Shutdown
July 18, 2000
TYPICAL CHARACTERISTICS (Cont.)
SC2041
Figure 9: Inrush Current, Device Enabled Into 100µF and 10ΩΩΩΩ
Top Trace: V Bottom Trace: I
SHDN
OUT
, 5V/div.
, 0.2A/div.
Timebase: 2.5ms/div.
= 5V, R
V
IN
= 10Ω, C
OUT
= 100µF
OUT
Figure 10: Inrush Current, Device Enabled Into 470µF and 10ΩΩΩΩ
Top Trace: V Bottom Trace: I
SHDN
OUT
, 5V/div.
, 0.2A/div.
Timebase: 2.5ms/div.
= 5V, R
V
IN
= 10Ω, C
OUT
= 470µF
OUT
APPLICATIONS INFORMATION
Theory Of Operation
The SC2041 is a current limited 80mΩ power switch with error reporting and enable features. The power switch is an N-channel MOSFET with its gate driven by an internal charge pump. The switch has been de­signed to turn on slowly (1.7ms typical) to minimize inrush currents at turn-on.
The Shutdown pin (SHDN) is compatible with 3V or 5V logic, and when pulled high, shuts off the power switch, causing the device to enter a very low power shutdown mode, where it will draw less than 1µA from the supply. While enabled, the SC2041 draws only 100µA from the supply.
The power switch has current limit detection circuitry which will limit the current through the s witch to 0.85A (typical) and reduce the output voltage accordingly. When c urrent limit is entered, the open drain Flag pin (FLG) is asserted low, indicating a fault condition. If an overcurrent or short condition is continuous , the power dissipation in the switch will cause the junction temper­ature to rise, triggering the therm al protection circuitry
to shut the switch down (at TJ = 150°C typical). This will shut off the output current altogether, and also cause the Flag pin to be asserted low. Once the junction temperature has dropped by 20°C (typical), the device will start up once more in a controlled manner.
The SC2041 will operate from supply voltages as low as 2.8V, and internal undervoltage lockout circuitry ensures that the power switch will be turned off at power-up, even if the device is enabled. Once the UVLO threshold voltage (2.7V typical) is reached, the switch will turn on (if enabled) and slowly ramp up the output.
The SC2041 has been designed for use in USB appli­cations such as:
1) hosts or self- powered hubs that need to cur rent lim it downstream ports and report overcurrent conditions;
2) bus-powered hubs that need to be able to switch power to downstream ports, limit inrush currents at power-up (to less than a 44Ω resistor in par allel with a 10µF capacitor) and power-up and draw less than 100mA;
3) bus-powered functions that need to limit inrush currents at power-up (to less than a 44Ω resistor in parallel with a 10µF capacitor) and power-up and draw less than 100mA.
© 2000 SEMTECH CORP.
9
652 MITCHELL ROAD NEWBURY PARK CA 91320
July 18, 2000
HotSwitch™ USB Power Distribution Switch With Shutdown
SC2041
APPLICATIONS INFORMATION (Cont.)
Component Selection - General
A 0.1µF or greater ceram ic bypass capacitor is recom ­mended at the device input. This should be placed
U1 SC2041
1
C1
0.1uF
2 3 4 5
VBUS IN
Shutdown Signal From USB Controller
Flag Output To USB Controller
R1
close to the input pin (IN) and routed directly to ground. A low ESR electrolytic capacitor is recommended at the output, higher values should be used for heavy loads to reduce ringing at the output (and hence input). Bypass the output with a 0.1µF to 1µF ceramic capacitor to improve immunity to short circuit transients.
Shutdown
The shutdown pin (SHDN) input is a 3V or 5V compatible enable/disable. Pulling this pin high shuts down the power switch and the SC2041 will draw < 1µA from the supply. Pulling this pin low will enable the device.
Error Flag
The error flag (F LG) output is an open drain N-channel MOSFET. Its output is pulled low during overcurrent, input undervoltage and thermal shutdown conditions. Connection of high capacitance loads to the output c an cause momentar y overcurrent conditions due to inr ush current and trigger fals e error flag assertion. This c an be reduced by using low ESR output capacitors to provide a low impedance source for hot-plug events. The addition of an RC filter between FLG and the USB controller can resolve this easily. This pin also requires a pull-up resistor for a high signal when not asserted.
Overcurrent
GND IN IN SHDN FLG
8
OUT
7
OUT
6
OUT
C2
0.1uFC322uF
VBUS OUT
overcurrent circuitry reacts. Once the cur rent limit cir­cuitry trips, the current is lim ited to 0.85A and FLG is asserted low. Refer to Figure 7 on page 8.
3) the load gradually increases beyond 500mA. In this case, the current will be allowed to rise until it reaches the Current Limit Trip Threshold, at which point the current will drop back to 0.85A and F LG will ass ert low. Refer to figures 4 and 5 on page 7 and 8.
Thermal Sensing
An internal thermal shutdown circuit turns off the power switch when the die temperature exceeds 150°C (typical). The FLG pin asserts low signaling a fault condition. Built-in hysteresis prevents the switch f rom turning back on until the die temperature has cooled approximately 20°C. The switch will continue to cycle on and off until the fault condition is removed. The thermal sense c ircuit functions only when the switch is enabled.
Undervoltage Lockout
An undervoltage lockout circ uit monitors the input volt­age and prevents the power switch from turning on until the input voltage (IN) exceeds 2.7V (typical). If the input voltage falls and drops below 2.4V (typical), the under­voltage circuitry turns off the power switch and the FLG pin asserts low. The undervoltage lockout functions only when the switch is enabled.
Thermal Considerations
Since the on-resistance of the power switch is so low, the SC2041 can pass large currents without requiring a large package to dissipate the heat. The worst-case power dissipation (under norm al operating conditions) is given by:
PIr
DMAX OUT ONMAX() ()
So for I
2
()=•
= 500mA and r
OUT
= 150mΩ (at VIN =
ON(MAX)
3.3V), the maximum power dissipation is:
There are three overcurrent situations to be consid­ered:
1) the output is already short before the device is enabled or power is applied. In this case, the SC2041 immediately detects the short, and the output current will slowly ramp up to the current limit value, and FLG will assert low. Refer to Figure 6 on page 8.
2) a short occurs while the device is enabled. In this case, very high current may flow initially while the
© 2000 SEMTECH CORP.
PmW
DMAX()
2
(.) . .=•=0 5 0 150 37 5
The junction temperatur e can be calculated using the following equation:
TT P
=+ •θ
JAJADMAX
Inserting T
()
= 85°C, θJA = 130°C/W (pack age thermal
A
impedance for minimum line widths and no internal
10
652 MITCHELL ROAD NEWBURY PARK CA 91320
July 18, 2000
HotSwitch™ USB Power Distribution Switch With Shutdown
SC2041
APPLICATIONS INFORMATION (Cont.)
power planes) and P worst-case T
TC
=+ • =°85 130 0 0375 90.
J
to be:
J
Thus it can be seen that this device does not require any additional copper area for heatsinking under normal operating conditions. Sustained overcurr ents or short circuits will rapidly heat T activating the thermal shutdown circuitry.
= 37.5mW , we calculate the
D(MAX)
> 150°C, thus
J
TYPICAL APPLICATIONS CIRCUITS
Self-Powered Hub, Individual Port Power Management:
A self-powered hub must supply a continuous 500m A of current to each downstream port. Since an internal power supply is used to supply the power, self-powered hubs are required to implem ent 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 SC2041 to provide individual port overcurrent protection & power switching for maximum port protection. Under fault conditions, the SC2041 provides the short-circuit current limiting function and has a fault flag logic output
Layout Considerations
The ceramic bypass capacitors for IN and O UT should be connected as close to the relevant device pins as possible. The bulk output capacitors required by the USB specification should be plac ed close to the USB connector to provide a low impedance source for hot plug purposes. Ferrite beads should be placed on the
and Ground pins of the downstream connectors to
V
BUS
reduce the droop on adjacent ports during hot plug events.
for notifying the hub controller. The USB hub can use the SC2041 to remove power from the faulty port, allowing the other ports to operate normally.
Since USB is a hot insertion and re m oval system, USB ports are subject to electrostatic dis charge (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 requirem ents of IEC 1000-4-2. The SC5205 LDO regulator is used to power the hub controller from the hub’s 5V power supply.
+5V
GND
5V Power Supply
D+
D-
VBUS
GND
Upstream Port
C1
4.7uF
U2
1
VIN
VO
2
GND
3 4
EN BYP
SC5205-3.3
R1 100k
EN
OC
D0D+ D0D-
5
C2 10nF
C3
4.7uF
VCC
D1D+ D1D-
USB Controller
C4
0.1uF
U3 SC2041
1
GND
OUT
2
IN
OUT
3
IN
OUT
4 5
SHDN FLG
U4
I/O1 I/O2 I/O3 I/O4 REF2
SRDA05-4
8 7 6
C5 33uF
REF1 REF1 REF2
Ferrite Bead
Ferrite Bead
VBUS D+ D­GND
Downstream Port
Notes: (1) One port only shown for simplicity. (2) 33µF output capacitor assumes four downstream ports for this hub, therefore meeting the USB specification requirement of 120µF minimum capacitance per hub. (3) The SRDA05-4 shown would also protect lines D2D+ and D2D-.
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
11
HotSwitch™ USB Power Distribution Switch With Shutdown
July 18, 2000
TYPICAL APPLICATIONS CIRCUITS (Cont.)
SC2041
Bus-Powered Hub, Ganged-Port Power Management:
A bus-powered hub distributes power and data from an input port to downstream ports. It m us t 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 lim iting is als o r equired to pr event power supply drooping. The circuit below utilizes the SC2041 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,
R1 100k
D+
D-
VBUS
GND
Upstream Port
U1
1 2 3
C1
4.7uF
4
1
4
23
SR05
U2
1
VIN
2
GND
3 4
EN BYP
SC5205-3.3
5
VO
C3
4.7uF
C2 10nF
D0D+ D0D-
VCC
D1D+
D1D-
D2D+
D2D-
D3D+
D3D-
D4D+
D4D-
USB Controller
EN OC OC OC OC
the USB controller will remove power to all of the ganged ports. For individual port management, additional SC2041s may be used.
Since USB is a hot insertion and re m oval system, USB ports are subject to electrostatic dis charge (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 requirem ents of IEC 1000-4-2. On the upstream port, the SR05 provides ESD pr otec­tion to the above levels for one line pair. The SC5205 LDO regulator is used to power the hub controller from the upstream bus.
U3 SC2041
C4
0.1uF
1 2 3 4 5
GND IN IN SHDN FLG
OUT OUT OUT
8 7 6
U4
I/O1 I/O2 I/O3 I/O4 REF2
SRDA05-4
REF1 REF1 REF2
U5
I/O1 I/O2 I/O3 I/O4 REF2
SRDA05-4
REF1 REF1 REF2
C5 33uF
C6 33uF
C7 33uF
C8 33uF
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
Ferrite Bead
VBUS D+ D­GND
Downstream Port
VBUS D+ D­GND
Downstream Port
VBUS D+ D­GND
Downstream Port
VBUS D+ D­GND
Downstream Port
Note: (1) 33µF output capacitor per port meets the USB specification minimum capacitance requirement of 120µF per hub.
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
12
HotSwitch™ USB Power Distribution Switch With Shutdown
July 18, 2000
TYPICAL APPLICATIONS CIRCUITS (Cont.)
SC2041
High-Power or Low-Power Bus-Powered Function:
Both low-power and high-power bus-powered functions must draw less than 100mA at startup. At this time, they must also present a load of less than the parallel combination of a 44Ω resistor and a 10µF capacitor. After startup, high powered functions may then draw up to 500mA. The circuit below utilizes the SC2041 to provide inrush current lim iting and power switching for the internal function.
U1
D+
D-
VBUS
GND
Upstream Port
1 2 3
C1 10uF
4
1
4
23
SR05
U2
1
VIN
2
GND
3 4
EN BYP
SC5205-3.3
D0D+ D0D-
5
VO
C2 10nF
C3
4.7uF
VCC
USB Controller
Since USB is a hot insertion and re m oval system, USB ports are subject to electrostatic dis charge (ESD). The SR05 provides ESD protection on the upstream data and power lines. With proper layout the port is hard­ened to greater than 15kV, meeting the requirements of IEC 1000-4-2. The SC5205 LDO regulator is used to power the hub controller from the upstream bus.
U3 SC2041
1
R1 100k
EN OC
2 3 4 5
C4
0.1uF
GND IN IN SHDN FLG
OUT OUT OUT
8 7 6
C5 10uF
VCC GND
Internal Function
Note: (1) 33µF output capacitor per port meets the USB specification minimum capacitance of 120µF per hub.
13
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
July 18, 2000
OUTLINE DRAWING - SO-8
HotSwitch™ USB Power Distribution Switch With Shutdown
JEDEC
REF: MS-012AA
SC2041
LAND PATTERN - SO-8
ECN00-1199
© 2000 SEMTECH CORP.
14
652 MITCHELL ROAD NEWBURY PARK CA 91320
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