RT9711A/B/C/D
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DS9711A/B/C/D-03 April 2011 www.richtek.com
80mΩΩ
ΩΩ
Ω, 1.5A/0.6A High-Side Power Switches with Flag
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
General Description
The RT9711A/B/C/D are cost-effective, low voltage, single
N-MOSFET high-side power switches, optimized for self-
powered and bus-powered Universal Serial Bus (USB)
applications. The RT9711 series are equipped with a
charge pump circuitry to drive the internal MOSFET switch.
The switch's low RDS(ON), 80mΩ, meets USB voltage drop
requirements. A flag output is available to indicate fault
conditions to the local USB controller.
Additional features include soft-start to limit inrush current
during plug-in, thermal shutdown to prevent catastrophic
switch failure from high-current loads, under-voltage
lockout (UVLO) to ensure that the device remains off
unless there is a valid input voltage present, fault current
is limited to typically 2.5A for RT9711A/B in dual ports
and 1A for RT9711C/D in single port in accordance with
the USB power requirements, lower quiescent current as
25μA making this device ideal for portable battery-operated
equipment.
The RT9711 series are available in SOT-23-5, TSOT-23-5,
SOP-8 and MSOP-8 packages fitting different aspect of
broad applications.
Features
zz
zz
zCompliant to USB Specifications
zz
zz
zBuilt-In N-MOSFET
``
``
` T ypical RDS(ON) : 80mΩΩ
ΩΩ
Ω (SOT-23-5 & TSOT-23-5) and
90mΩΩ
ΩΩ
Ω (SOP-8 & MSOP-8)
zz
zz
zOutput Can Be Forced Higher Than Input (Off-State)
zz
zz
zLow Supply Current :
25μμ
μμ
μA Typical at Switch On State
1μμ
μμ
μA Typical at Switch Off State
zz
zz
zGuaranteed 1.5A for RT9711A/B and 0.6A for
RT9711C/D Continuous Load Current
zz
zz
zWide Input Voltage Ranges : 2.5V to 5.5V
zz
zz
zOpen-Drain Fault Flag Output
zz
zz
zHot Plug-In Application (Soft-Start)
zz
zz
z1.7V Typical Under-Voltage Lockout (UVLO)
zz
zz
zCurrent Limiting Protection
zz
zz
zThermal Shutdown Protection
zz
zz
zReverse Current Flow Blocking (no body diode)
zz
zz
zSmallest SOT-23-5 and TSOT-23-5 Packages
Minimizes Board Space
zz
zz
zUL Approved−−
−−
−E219878
zz
zz
zTUV IEC60950-1 : 2005 Certified
zz
zz
zRoHS Compliant and 100% Lead (Pb)-Free
Applications
zUSB Bus/Self Powered Hubs
zUSB Peripherals
zACPI Power Distribution
zPC Card Hot Swap
zNotebook, Motherboard PCs
zBattery-Powered Equipment
zHot-Plug Power Supplies
zBattery-Charger Circuits
Note :
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Ordering Information
RT9711
Package Type
B : SOT-23-5
BG : SOT-23-5 (G-Type)
J5 : TSOT-23-5
S : SOP-8
F : MSOP-8
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Output Current/EN Function
A : 1.5A/Active High
B : 1.5A/Active Low
C : 0.6A/Active High
D : 0.6A/Active Low
RT9711A/B/C/D
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Function Block Diagram
Functional Pin Description
Pin Name Pin Function
VIN Power Input Voltage
VOUT Output Voltage
GND Ground
EN/EN Chip Enable. Never let this pin floating.
(Active High for RT9711A/C, Active Low
for RT9711B/D)
FLG Open-Drain Fault Flag Output
Typical Application Circuit
Pin Configurations
(TOP VIEW)
Note: A low-ESR 150μF aluminum electrolytic or tantalum
between VOUT and GND is strongly recommended to meet
the 330mV maximum droop requirement in the hub VBUS.
(see Application Information Section for further details)
SOT-23-5 (G-Type) SOP-8/MSOP-8
SOT-23-5/TSOT-23-5
Gate
Control
Output Voltage
Detection
Delay
Oscillator
UVLO
Charge
Pump
Bias
Thermal
Protection
Current
Limiting
VOUT
VIN
GND
EN/EN
FLG
GND
VOUT VIN
4
23
5
FLG EN/EN VOUT GND NC
VIN
4
23
5
EN/EN
GND
VIN
VIN VOUT
VOUT
VOUT
2
3
45
8
7
6
EN/EN FLG
VIN
VOUT
GND
RT9711A/B/C/D
+
Over -Current
VBUS
D+
D-
GND
USB Controller
1µF
150µF
10µF
Supply
Voltage 5V
Pull-Up Resistor (10K to 100K)
Ferrite
Beads Data
RT9711A/C
Chip Enable
RT9711B/D
Chip Enable
FLG
EN/EN
CIN
COUT
RT9711A/B/C/D
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Absolute Maximum Ratings (Note 1)
zSupply Voltage --------------------------------------------------------------------------------------------------------- 6.5V
zChip Enable Input Voltage ------------------------------------------------------------------------------------------- −0.3V to 6.5V
zFlag Voltage ------------------------------------------------------------------------------------------------------------ 6.5V
zPower Dissipation, PD @ TA = 25°C
SOT-23-5, TSOT-23-5 ------------------------------------------------------------------------------------------------- 0.4W
SOP-8, MSOP-8 ------------------------------------------------------------------------------------------------------- 0.625W
zPackage Thermal Resistance (Note 2)
SOT-23-5, TSOT-23-5, θJA ------------------------------------------------------------------------------------------- 250°C/W
SOP-8, MSOP-8, θJA ------------------------------------------------------------------------------------------------- 160°C/W
zJunction Temperature ------------------------------------------------------------------------------------------------- 150°C
zLead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------- 260°C
zStorage Temperature Range ---------------------------------------------------------------------------------------- −65°C to 150°C
zESD Susceptibility (Note 3)
HBM (Human Body Mode) ------------------------------------------------------------------------------------------ 2kV
MM (Machine Mode) -------------------------------------------------------------------------------------------------- 200V
Electrical Characteristics
Recommended Operating Conditions (Note 4)
zSupply Input Voltage -------------------------------------------------------------------------------------------------- 2.5V to 5.5V
zChip Enable Input Voltage ------------------------------------------------------------------------------------------- 0V to 5.5V
zJunction Temperature Range ---------------------------------------------------------------------------------------- −40°C to 125°C
zAmbient Temperature Range ---------------------------------------------------------------------------------------- −40°C to 85°C
Parameter Symbol Test Conditions Min Typ Max Units
Switch On
Resistance
(RT9711A/B)
SOT-23-5, TSOT-23-5
RDS(ON)
IOUT = 1A, VIN = 5V
-- 80 100
mΩ
SOP-8, MSOP-8 -- 90 110
Switch On
Resistance
(RT9711C/D)
SOT-23-5, TSOT-23-5
IOUT = 0.5A, VIN = 5 V
-- 80 100
mΩ
S OP-8, M SOP -8 -- 90 11 0
Supply C urrent ISW_ON switch on, RLOAD Open -- 25 45 μA
ISW_OFF switch off, RLOAD Open -- 0.1 1
EN /EN
Threshold
Logic-Low Voltage VIL V
IN = 2.5V to 5.5V -- -- 0.8 V
Logic-High Voltage VIH V
IN = 2.5V to 5.5V 2.0 -- -- V
EN/EN Input Current IEN/EN V
EN/EN = 0V to 5.5V -- 0.01 -- μA
Output Leakage Current ILEAK V
EN = 0V, VEN = 5 V, R LOAD = 0Ω -- 0.5 10 μA
Output Turn-On Rise Time TON_RISE 10% to 90% of VOUT ris ing -- 400 -- us
Current Limit RT9711A/B
ILIM Current Ramp (< 0.1A/ms) on
VOUT
1.6 2.5 3. 2 A
RT9711C/D 0.7 1 1.4 A
(VIN = 5V, CIN = COUT = 1μF, TA = 25°C, unless otherwise specified)
To be continued
RT9711A/B/C/D
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Parameter Symbol Test Conditions Min Typ Max Units
Sho rt Circuit
Fold-Back Current
RT9711A/B
ISC_FB VOUT = 0V, measured prior to
thermal shutdown
-- 1 --
A
RT9711C/D -- 0.8 --
FLAG Output R esistance RFLG ISINK = 1 mA -- 20 400
Ω
FLAG Off Current IFLG_OF F V
FLG = 5V -- 0.01 1 μA
FLAG Delay Time (Note 5) tD From fault condition to FLG
assertion 5 12 20 ms
Shutdown Pull-Low Resistance RDS VEN
= 0V, VEN = 5V -- 75 150
Ω
Under-voltage Lockout VUVLO V
IN increasing 1.3 1.7 -- V
Under-voltage Hysteresis ΔVUVLO V
IN decreasing -- 0.1 -- V
Thermal Shutdown Protection TSD -- 130 --
°C
Thermal Shutdown Hysteresis ΔTSD -- 20 --
°C
Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for
stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may remain possibility to affect device reliability.
Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective thermal conductivity single layer test board of
JEDEC 51-3 thermal measurement standard.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Note 5. The FLAG delay time is input voltage dependent, see“ Typical Operating Characteristics” graph for further details.
RT9711A/B/C/D
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Typical Operating Characteristics
Supply Curre nt vs. Input Voltage
0
5
10
15
20
25
30
35
40
22.533.544.555.5
Input Voltage (V)
Supply Current (uA)
SOT-23-5, RL = Open
CIN = COUT = 33μF/Electrolytic
Switch On Resistance vs. Temperature
0
0.05
0.1
0.15
0.2
0.25
-40 -20 0 20 40 60 80 100 120
Temperature
Switch On Resistance (Ω)
(°C)
SOT-23-5, VIN = 5V, ILOAD = 1.5A
CIN = 1μF/X7R, COUT = 10μF/X7R
Switch On Resistance vs. Temperature
0
0.05
0.1
0.15
0.2
0.25
-40 -20 0 20 40 60 80 100 120
Temperature
Switch On Resistance (Ω)
(°C)
SOP-8, VIN = 5V, ILOAD = 1.5A
CIN = 1uF/X7R, COUT = 10μF/X7R
Switch on Resistance vs. Input Voltage
20
40
60
80
100
120
140
22.5 33.5 44.5 55.5
Input Voltage (V)
Switch on Resistance (mΩ
)
SOT-23-5, ILOAD = 1.5A
CIN = COUT = 33μF/Electrolytic
Supply Curre nt vs. Temperature
0
5
10
15
20
25
30
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
Supply Current (uA
)
VIN = 5V, Switch On, RLOAD Open
CIN = COUT = 33μF/Electrolytic
Current Limit vs. Input Voltage
1
1.2
1.4
1.6
1.8
2
22.533.544.555.5
Input Voltage (V)
Current Limit (A)
RT9711A/B, VIN = VEN = 5V
CIN = 1μF/X7R, COUT = 10μF/X7R
RT9711A/B/C/D
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EN Pin Threshold Voltage vs. Tem perature
0
0.4
0.8
1.2
1.6
2
2.4
-40 -20 0 20 40 60 80 100 120
Temperature
EN Pin Threshold Voltage (V)
RT9711B, VIN = 5V, ILOAD = 100mA
CIN = COUT = 33μF/Electrolytic
(°C)
Turn-Off Falling Time vs. Temperature
0
20
40
60
80
100
-40 -20 0 20 40 60 80 100 120
Temperature
Turn-Off Falling Time (us)
VIN = 5V, RLOAD = 30Ω
CIN = 33μF/Electrolytic
COUT = 1μF/Electrolytic
(°C)
Turn-Off Leakage Current v s . Te mpe rature
0
0.5
1
1.5
2
2.5
3
3.5
4
-40 -20 0 20 40 60 80 100 120
Temperature
Turn-Off Leakage Current (uA)
VIN = 5V, RLOAD = 0Ω
CIN = 33μF/Electrolytic
COUT = 1μF/X7R
(°C)
Turn-On Rising Time vs. Temperature
0
100
200
300
400
500
600
700
-40 -20 0 20 40 60 80 100 120
Temperature
Turn-On Rising Time (us)
VIN = 5V, RLOAD = 30Ω
CIN = 33μF/Electrolytic
COUT = 1μF/Electrolytic
(°C)
EN PinThreshold Voltage vs . Input Voltage
0
0.4
0.8
1.2
1.6
2
22.5 33.544.5 55.5
Input Voltage (V)
EN Threshold Voltage (V)
RT9711B, ILOAD = 100mA
CIN = COUT = 33μF/Electrolytic
Current Lim it vs. Tempe rature
1
1.2
1.4
1.6
1.8
2
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
Current Limit (A)
RT9711A/B, VIN = 5V
CIN = 1μF/X7R, COUT = 10μF/X7R
RT9711A/B/C/D
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FLAG Delay Time vs. Input Voltage
0
4
8
12
16
20
22.533.544.555.5
Input Voltage(V)
FLAG Delay Time (ms)
RLOAD = 1Ω
CIN = COUT = 33μF/Electrolytic
Flag Response with Ramped Load
Time (2.5ms/Div)
IOUT
(1A/Div)
VOUT
(5V/Div)
SOT-23-5, VIN = 5V
CIN = COUT = 33μF/Electrolytic
VLAG
(5V/Div)
Load Transient Response
Time (1ms/Div)
VOUT
(1V/Div)
IOUT
(1A/Div)
VIN = 5V, COUT = 1μF
CIN = 33μF/Electrolytic
RLOAD = 1kΩ to 2.2Ω
4.8V
1.5A
Swith Off Supply Current vs. Temperature
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
-40 -20 0 20 40 60 80 100 120
Temperature
Swith Off Supply Current (uA)
VIN = 5V, RLOAD = Open
CIN = COUT = 33μF/Electrolytic
(°C)
Flag Delay Tim e vs. Temperature
7
8
9
10
11
12
13
14
15
16
-40 -20 0 20 40 60 80 100 120
Temperature
Flag Delay Time (ms)
RLOAD = 1Ω, VIN = 5V
CIN = COUT = 33μF/Electrolytic
(°C)
UVLO Threshold vs. Temperature
0
0.4
0.8
1.2
1.6
2
2.4
-40 -20 0 20 40 60 80 100 120
Temperature
UVLO Threshold (V)
VIN Increasing, ILOAD = 15mA
CIN = COUT = 33μF/Electrolytic
(°C)
RT9711A/B/C/D
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Turn Off Response
Time (100μs/Div)
VEN
(5V/Div)
VOUT
(5V/Div) RT9711B, VIN = 5V, RLOAD = 30Ω
CIN = 33μF/Electrolytic
COUT = 1μF/Electrolytic
UVLO at Rising
VIN
(1V/Div)
VOUT
(1V/Div)
SOT-23-5, VIN = 5V,
RLOAD = 30Ω, COUT = 1μF
CIN = 33μF/Electrolytic
Time (2.5ms/Div)
Flag Response during Short Circuit
Time (5ms/Div)
VFLG
(5V/Div)
IOUT
(1A/Div)
VIN = 5V, RLOAD = 0Ω
CIN = COUT = 33μF/Electrolytic
VEN
(5V/Div)
UVLO at Falling
Time (5ms/Div)
VIN
(1V/Div)
VOUT
(1V/Div)
VIN = 5V, RLOAD = 30Ω
COUT = 1μF
CIN = 33μF/Electrolytic
Flag Response during Over Load
Time (5ms/Div)
VFLG
(5V/Div)
IOUT
(1A/Div)
VIN = 5V, RLOAD = 2Ω
CIN = COUT = 33μF/Electrolytic
VOUT
(5V/Div)
Turn On Response
Time (100μs/Div)
RT9711B, VIN = 5V
RLOAD = 30Ω
CIN = 33μF/Electrolytic
COUT = 1μF/Electrolytic
VEN
(5V/Div)
VOUT
(5V/Div)
RT9711A/B/C/D
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Output Voltage vs . Output Curre nt
0.6
1.0
1.4
1.8
2.2
2.6
3.0
3.4
3.8
4.2
4.6
5.0
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Output Current (A)
Output Voltage (V)
RT9711A, VIN = 5V
TA = 25°C
TA = -45°CTA = 85°C
Output Voltage vs. Output Curren t
0.6
1.0
1.4
1.8
2.2
2.6
3.0
3.4
3.8
4.2
4.6
5.0
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Output Current (A)
Output Voltage (V)
RT9711C, VIN = 5V
TA = 25°C
TA = -45°C
TA = 85°C
Current L imit Thresh old vs . In put Voltag e
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
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Input Voltage (V)
Current Limit Threshold (A
)
RT9711C, VIN = 5V
TA = 25°C
TA = -45°C
TA = 85°C
Current Limit Threshold vs. Input Voltage
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
Current Limit Threshold (A
)
RT9711A, VIN = 5V
TA = 25°C
TA = -45°C
TA = 85°C
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Soft Start for Hot Plug-In Applications
In order to eliminate the upstream voltage droop caused
by the large inrush current during hot-plug events, the
“soft-start” feature effectively isolates the power source
from extremely large capacitive loads, satisfying the USB
voltage droop requirements.
Fault Flag
The RT9711 series provides a FLG signal pin which is an
N-Channel open drain MOSFET output. This open drain
output goes low when VOUT < VIN − 1V, current limit or the
die temperature exceeds 130°C approximately. The FLG
output is capable of sinking a 10mA load to typically 200mV
above ground. The FLG pin requires a pull-up resistor,
this resistor should be large in value to reduce energy
drain. A 100kΩ pull-up resistor works well for most
applications. In the case of an over-current condition, FLG
will be asserted only after the flag response delay time,
tD, has elapsed. This ensures that FLG is asserted only
upon valid over-current conditions and that erroneous error
reporting is eliminated.
For example, false over-current conditions may occur
during hot-plug events when extremely large capacitive
loads are connected and causes a high transient inrush
current that exceeds the current limit threshold. The FLG
response delay time tD is typically 10ms.
Under-Voltage Lockout
Under-voltage lockout (UVLO) prevents the MOSFET
switch from turning on until input voltage exceeds
approximately 1.7V. If input voltage drops below
approximately 1.3V, UVLO turns off the MOSFET switch,
FLG will be asserted accordingly. Under-voltage detection
functions only when the switch is enabled.
Current Limiting and Short-Circuit Protection
The current limit circuitry prevents damage to the MOSFET
switch and the hub downstream port but can deliver load
current up to the current limit threshold of typically 2.5A
through the switch of RT9711A/B and 1A for RT9711C/D
respectively. When a heavy load or short circuit is applied
to an enabled switch, a large transient current may flow
until the current limit circuitry responds. Once this current
Applications Information
The RT9711A/B/C/D are single N-MOSFET high-side
power switches with enable input, optimized for self-
powered and bus-powered Universal Serial Bus (USB)
applications. The RT9711 series are equipped with a
charge pump circuitry to drive the internal N-MOSFET
switch; the switch's low RDS(ON), 80mΩ, meets USB
voltage drop requirements; and a flag output is available
to indicate fault conditions to the local USB controller.
Input and Output
VIN (input) is the power source connection to the internal
circuitry and the drain of the MOSFET. VOUT (output) is
the source of the MOSFET. In a typical application, current
flows through the switch from VIN to VOUT toward the load.
If VOUT is greater than VIN, current will flow from VOUT to
VIN since the MOSFET is bidirectional when on.
Unlike a normal MOSFET, there is no a parasitic body
diode between drain and source of the MOSFET, the
RT9711A/B/C/D prevents reverse current flow if VOUT being
externally forced to a higher voltage than VIN when the
output disabled (VEN < 0.8V or VEN > 2V).
D
G
S
D
G
S
Normal MOSFET RT9711A/B/C/D
Chip Enable Input
The switch will be disabled when the EN/EN pin is in a
logic low/high condition. During this condition, the internal
circuitry and MOSFET are turned off, reducing the supply
current to 0.1μA typical. Floating the EN/EN may cause
unpredictable operation. EN should not be allowed to go
negative with respect to GND. The EN/EN pin may be
directly tied to VIN (GND) to keep the part on.
RT9711A/B/C/D
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DS9711A/B/C/D-03 April 2011 www.richtek.com
limit threshold is exceeded the device enters constant
current mode until the thermal shutdown occurs or the
fault is removed.
And for SOP-8 and MSOP-8 packages, the thermal
resistance θJA is 160°C/W. The maximum power
dissipation at TA = 25°C can be calculated by following
formula :
PD(MAX) = (125°C − 25°C) / 250°C/W = 0.4W for
SOT-23-5 and TSOT-23-5 packages
PD(MAX) = (125°C − 25°C) / 160°C/W = 0.625W for
SOP-8 and MSOP-8 packages
The maximum power dissipation depends on operating
ambient temperature for fixed TJ(MAX) and thermal
resistance θJA. For RT9711A/B/C/D packages, the Figure
1 of derating curves allows the designer to see the effect
of rising ambient temperature on the maximum power
allowed.
Figure 1. Derating Curves for RT9711A/B/C/D Package
Universal Serial Bus (USB) & Power Distribution
The goal of USB is to be enabled device from different
vendors to interoperate in an open architecture. USB
features include ease of use for the end user, a wide range
of workloads and applications, robustness, synergy with
the PC industry, and low-cost implement- ation. Benefits
include self-identifying peripherals, dynamically attachable
and reconfigurable peripherals, multiple connections
(support for concurrent operation of many devices), support
for as many as 127 physical devices, and compatibility
with PC Plug-and-Play architecture.
The Universal Serial Bus connects USB devices with a
USB host: each USB system has one USB host. USB
devices are classified either as hubs, which provide
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 25 50 75 100 125
Ambient Temperature
Maximum Power Dissipation (W)
Single Layer PCB
(°C)
SOP-8, MSOP-8
SOT-23-5, TSOT-23-5
Thermal Shutdown
Thermal shutdown is employed to protect the device from
damage if the die temperature exceeds approxi- mately
130°C. If enabled, the switch automatically restarts when
the die temperature falls 20°C. The output and FLG signal
will continue to cycle on and off until the device is disabled
or the fault is removed.
Power Dissipation
The junction temperature of the RT9711 series depend on
several factors such as the load, PCB layout, ambient
temperature and package type. The output pin of
RT9711A/B/C/D can deliver the current of up to 1.5A
(RT9711A/B), and 0.6A (RT9711C/D) respectively over the
full operating junction temperature range. However, the
maximum output current must be derated at higher
ambient temperature to ensure the junction temperature
does not exceed 100°C. With all possible conditions, the
junction temperature must be within the range specified
under operating conditions. Power dissipation can be
calculated based on the output current and the RDS(ON) of
switch as below.
PD = RDS(ON) x IOUT2
Although the devices are rated for 1.5A and 0.6A of output
current, but the application may limit the amount of output
current based on the total power dissipation and the
ambient temperature. The final operating junction
temperature for any set of conditions can be estimated
by the following thermal equation :
PD (MAX) = (TJ (MAX) - TA) / θJA
Where TJ(MAX) is the maximum operation junction
temperature 125°C, TA is the ambient temperature and the
θJA is the junction to ambient thermal resistance.
The junction to ambient thermal resistance θJA is layout
dependent. For SOT-23-5 and TSOT-23-5 packages, the
thermal resistance θJA is 250°C/W on the standard JEDEC
51-3 single-layer thermal test board.
RT9711A/B/C/D
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DS9711A/B/C/D-03 April 2011www.richtek.com
additional attachment points to the USB, or as functions,
which provide capabilities to the system (for example, a
digital joystick). Hub devices are then classified as either
Bus-Power Hubs or Self-Powered Hubs.
A Bus-Powered Hub draws all of the power to any internal
functions and downstream ports from the USB connector
power pins. The hub may draw up to 500mA from the
upstream device. External ports in a Bus-Powered Hub
can supply up to 100mA per port, with a maximum of four
external ports.
Self-Powered Hub power for the internal functions and
downstream ports does not come from the USB, although
the USB interface may draw up to 100mA from its
upstream connect, to allow the interface to function when
the remainder of the hub is powered down. The hub must
be able to supply up to 500mA on all of its external
downstream ports. Please refer to Universal Serial
Specification Revision 2.0 for more details on designing
compliant USB hub and host systems.
Over-Current protection devices such as fuses and PTC
resistors (also called polyfuse or polyswitch) have slow
trip times, high on-resistance, and lack the necessary
circuitry for USB-required fault reporting.
The faster trip time of the RT9711A/B/C/D power
distribution allow designers to design hubs that can operate
through faults. The RT9711A/B/C/D have low on-resistance
and internal fault-reporting circuitry that help the designer
to meet voltage regulation and fault notification
requirements.
Because the devices are also power switches, the designer
of self-powered hubs has the flexibility to turn off power to
output ports. Unlike a normal MOSFET, the devices have
controlled rise and fall times to provide the needed inrush
current limiting required for the bus-powered hub power
switch.
Supply Filter/Bypa ss Ca pa citor
A 1μF low-ESR ceramic capacitor from VIN to GND,
located at the device is strongly recommended to prevent
the input voltage drooping during hot-plug events. However,
higher capacitor values will further reduce the voltage droop
on the input. Furthermore, without the bypass capacitor,
an output short may cause sufficient ringing on the input
(from source lead inductance) to destroy the internal
control circuitry. The input transient must not exceed 6.5V
of the absolute maximum supply voltage even for a short
duration.
Output Filter Capacitor
A low-ESR 150μF aluminum electrolytic or tantalum
between VOUT and GND is strongly recommended to meet
the 330mV maximum droop requirement in the hub VBUS
(Per USB 2.0, output ports must have a minimum 120μF
of low-ESR bulk capacitance per hub). Standard bypass
methods should be used to minimize inductance and
resistance between the bypass capacitor and the
downstream connector to reduce EMI and decouple voltage
droop caused when downstream cables are hot-insertion
transients. Ferrite beads in series with VBUS, the ground
line and the 0.1μF bypass capacitors at the power
connector pins are recommended for EMI and ESD
protection. The bypass capacitor itself should have a low
dissipation factor to allow decoupling at higher frequencies.
Voltage Drop
The USB specification states a minimum port-output
voltage in two locations on the bus, 4.75V out of a Self-
Powered Hub port and 4.40V out of a Bus-Powered Hub
port. As with the Self-Powered Hub, all resistive voltage
drops for the Bus-Powered Hub must be accounted for to
guarantee voltage regulation (see Figure 7-47 of Universal
Serial Specification Revision 2.0 ).
The following calculation determines VOUT (MIN) for multi-
ple ports (NPORTS) ganged together through one switch (if
using one switch per port, NPORTS is equal to 1) :
VOUT (MIN) = 4.75V − [ II x ( 4 x RCONN + 2 x RCABLE ) ] −
(0.1A x NPORTS x RSWITCH ) − VPCB
Where
RCONN = Resistance of connector contacts
(two contacts per connector)
RCABLE = Resistance of upstream cable wires
(one 5V and one GND)
RSWITCH = Resistance of power switch
(80mΩ typical for RT9711A/B/C/D)
RT9711A/B/C/D
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DS9711A/B/C/D-03 April 2011 www.richtek.com
VPCB = PCB voltage drop
The USB specification defines the maximum resistance
per contact (RCONN) of the USB connector to be 30mΩ
and the drop across the PCB and switch to be 100mV.
This basically leaves two variables in the equation: the
resistance of the switch and the resistance of the cable.
If the hub consumes the maximum current (II) of 500mA,
the maximum resistance of the cable is 90mΩ.
The resistance of the switch is defined as follows :
RSWITCH = { 4.75V − 4.4V − [ 0.5A x ( 4 x 30mΩ + 2 x
90mΩ) ] − VPCB } ÷( 0.1A x NPORTS )
= (200mV − VPCB ) ÷( 0.1A x NPORTS )
If the voltage drop across the PCB is limited to 100mV,
the maximum resistance for the switch is 250mΩ for four
ports ganged together. The RT9711A/B/C/D, with its
maximum 100mΩ on-resistance over temperature, easily
meets this requirement.
Layout Considerations
For best performance of the RT9711 series, the following
guidelines muse be strictly followed :
`Input and output capacitors should be placed close to
the IC and connected to ground plane to reduce noise
coupling.
`The GND should be connected to a strong ground plane
for heat sink.
`Keep the main current traces as possible as short and
wide.
GND
EN
VIN
VOUT
The input and output capacitors should be
placed as close as possible to the IC.
GND
FLG
VIN
Figure 2. PCB Layout Guide
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Outline Dimension
AA1
e
b
B
D
C
H
L
SOT-23-5 Surface Mount Package
Dimensions In Millimeter s Dimensions In Inches
Symbol Min Max Min Max
A 0.889 1.295 0.035 0.051
A1 0.000 0.152 0.000 0.006
B 1.397 1.803 0.055 0.071
b 0.356 0.559 0.014 0.022
C 2.591 2.997 0.102 0.118
D 2.692 3.099 0.106 0.122
e 0.838 1.041 0.033 0.041
H 0.080 0.254 0.003 0.010
L 0.300 0.610 0.012 0.024
RT9711A/B/C/D
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DS9711A/B/C/D-03 April 2011 www.richtek.com
TSOT-23-5 Surface Mount Package
Dimensions In Millimeters Dimensions In Inches
Symbol Min Max Min Max
A 0.700 1.000 0.028 0.039
A1 0.000 0.100 0.000 0.004
B 1.397 1.803 0.055 0.071
b 0.300 0.559 0.012 0.022
C 2.591 3.000 0.102 0.118
D 2.692 3.099 0.106 0.122
e 0.838 1.041 0.033 0.041
H 0.080 0.254 0.003 0.010
L 0.300 0.610 0.012 0.024
AA1
e
b
B
D
C
H
L
RT9711A/B/C/D
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A
B
J
F
H
M
C
D
I
8-Lead SOP Plastic Package
Dimensions In Millimeters Dimension s In Inches
Symbol Min Max Min Max
A 4.801 5.004 0.189 0.197
B 3.810 3.988 0.150 0.157
C 1.346 1.753 0.053 0.069
D 0.330 0.508 0.013 0.020
F 1.194 1.346 0.047 0.053
H 0.170 0.254 0.007 0.010
I 0.050 0.254 0.002 0.010
J 5.791 6.200 0.228 0.244
M 0.400 1.270 0.016 0.050
RT9711A/B/C/D
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DS9711A/B/C/D-03 April 2011 www.richtek.com
Richtek Technology Corporation
Headquarter
5F, No. 20, Taiyuen Street, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit
design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be
guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.
Richtek Technology Corporation
Taipei Office (Marketing)
5F, No. 95, Minchiuan Road, Hsintien City
Taipei County, Taiwan, R.O.C.
Tel: (8862)86672399 Fax: (8862)86672377
Email: marketing@richtek.com
L
D
EE1
e
A
bA1 A2
Dimensions In Millimeters Dimension s In Inches
Symbol Min Max Min Max
A 0.810 1.100 0.032 0.043
A1 0.000 0.150 0.000 0.006
A2 0.750 0.950 0.030 0.037
b 0.220 0.380 0.009 0.015
D 2.900 3.100 0.114 0.122
e 0.650 0.026
E 4.800 5.000 0.189 0.197
E1 2.900 3.100 0.114 0.122
L 0.400 0.800
0.016 0.031
8-Lead MSOP Plastic Package
