RT9715EGBR [RICHTEK]
IC PWR SWITCH USB 1.1A SOT23-5;型号: | RT9715EGBR |
厂家: | RICHTEK TECHNOLOGY CORPORATION |
描述: | IC PWR SWITCH USB 1.1A SOT23-5 |
文件: | 总15页 (文件大小:332K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
RT9715
90mΩ, 2A/1.5A/1.1A/0.7A High-Side Power Switches
with Flag
General Description
Features
z 90mΩ (typ.) N-MOSFET Switch
z Operating Range : 2.7V to 5.5V
z Reverse Blocking Current
z Under Voltage Lockout
The RT9715 is a cost-effective, low-voltage, single
N-MOSFET high-side Power Switch IC for USB application.
Low switch-on resistance (typ. 90mΩ) and low supply
current (typ. 50uA) are realized in this IC.
z Deglitched Fault Report (FLG)
z Thermal Protection with Foldback
z Over Current Protection
The RT9715 integrates an over-current protection circuit,
a short fold back circuit, a thermal shutdown circuit and an
under-voltage lockout circuit for overall protection. Besides,
a flag output is available to indicate fault conditions to the
local USB controller. Furthermore, the chip also integrates
an embedded delay function to prevent miss-operation from
happening due to inrush-current. The RT9715 is an ideal
solution for USB power supply and can support flexible
applications since it is available in various packages such
as SOT-23-5, SOP-8, MSOP-8 and WDFN-8L 3x3.
z Short Circuit Protection
z UL Approved−E219878
z Nemko Approved−NO49621
z RoHS Compliant and Halogen Free
Applications
z USB Peripherals
z Notebook PCs
Ordering Information
RT9715
Pin Configurations
Package Type
B : SOT-23-5
(TOP VIEW)
VIN
EN/EN
VIN
EN/EN
BG : SOT-23-5 (G-Type)
BR : SOT-23-5 (R-Type)
S : SOP-8
5
4
5
4
2
3
2
3
F : MSOP-8
QW : WDFN-8L 3x3 (W-Type)
VOUT GND FLG
SOT-23-5
VOUT GND NC
SOT-23-5 (G-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
VOUT
VIN
Output Current/EN Function
A : 2A/Active High
B : 2A/Active Low
C : 1.5A/Active High
D : 1.5A/Active Low
E : 1.1A/Active High
F : 1.1A/Active Low
G : 0.7A/Active High
5
4
GND
8
7
6
5
VOUT
VOUT
VOUT
FLG
2
3
4
VIN
VIN
2
3
EN/EN
EN/EN
FLG GND
SOP-8/MSOP-8
SOT-23-5 (R-Type)
H : 0.7A/Active Low
GND
VIN
VIN
1
2
3
4
8
7
6
5
VOUT
VOUT
VOUT
FLG
Note :
Richtek products are :
9
EN/EN
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
WDFN-8L 3x3
` Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
DS9715-03 April 2011
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1
RT9715
Typical Application Circuit
Pull-Up Resistor (10K to 100K)
USB Controller
Over -Current
Supply Voltage
2.7V to 5.5V
VIN
FLG
C
1uF
IN
RT9715
RT9715A/C/E/G
Chip Enable
VOUT
V
BUS
EN/EN
D+
C
10uF
OUT
150uF
GND
D-
RT9715B/D/F/H
Chip Enable
GND
Ferrite
Beads
Data
Note : Alow-ESR 150uF 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)
Functional Pin Description
Pin No.
Pin Name
Pin Function
SOT-23-5 SOT-23-5 SOP-8 / WDFN-8L
SOT-23-5
(G-Type) (R-Type) MSOP-8
3X3
6 , 7 , 8 VOUT
1
2
3
4
5
--
1
2
--
4
5
3
5
2
1
3
4
--
6 , 7 , 8
Output Voltage.
Ground.
1
5
1
5
GND
FLG
EN/EN
VIN
Fault FLAG Output.
4
4
Chip Enable (Active High/Low).
Power Input Voltage.
2 , 3
--
2 , 3
--
NC
No Internal Connection.
The exposed pad must be soldered to a large
PCB and connected to GND for maximum
power dissipation.
9 (Exposed
Pad)
--
--
--
--
Function Block Diagram
VIN
Bias
EN/EN
Current
Limiting
UVLO
Gate
Control
Charge
Pump
Oscillator
Output Voltage
Detection
VOUT
Thermal
Protection
Auto Discharge
FLG
Delay
GND
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DS9715-03 April 2011
2
RT9715
Absolute Maximum Ratings (Note 1)
z Supply Input Voltage, VIN -------------------------------------------------------------------------------------------- 6V
z ENVoltage -------------------------------------------------------------------------------------------------------------- −0.3V to 6V
z FLAGVoltage ---------------------------------------------------------------------------------------------------------- 6V
z Power Dissipation, PD @ TA = 25°C
SOT-23-5 ---------------------------------------------------------------------------------------------------------------- 300mW
SOP-8 -------------------------------------------------------------------------------------------------------------------- 469mW
MSOP-8 ----------------------------------------------------------------------------------------------------------------- 469mW
WDFN-8L 3x3 ---------------------------------------------------------------------------------------------------------- 694mW
z Package Thermal Resistance (Note 2)
SOT-23-5, θJA ----------------------------------------------------------------------------------------------------------- 250°C/W
SOP-8, θJA -------------------------------------------------------------------------------------------------------------- 160°C/W
MSOP-8, θJA ------------------------------------------------------------------------------------------------------------ 160°C/W
WDFN-8L 3x3, θJA ----------------------------------------------------------------------------------------------------- 108°C/W
z Junction Temperature ------------------------------------------------------------------------------------------------- 150°C
z Lead Temperature (Soldering, 10 sec.)--------------------------------------------------------------------------- 260°C
z Storage Temperature Range ---------------------------------------------------------------------------------------- −65°C to 150°C
z ESD Susceptibility (Note 3)
HBM (Human Body Mode) ------------------------------------------------------------------------------------------ 2kV
MM (Machine Mode) -------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions (Note 4)
z Supply Input Voltage, VIN -------------------------------------------------------------------------------------------- 2.7V to 5.5V
z ENVoltage -------------------------------------------------------------------------------------------------------------- 0V to 5.5V
z Junction Temperature Range---------------------------------------------------------------------------------------- −40°C to 100°C
z Ambient Temperature Range---------------------------------------------------------------------------------------- −40°C to 85°C
Electrical Characteristics
(VIN = 5V, CIN = 1uF, COUT = 10uF, TA = 25°C, unless otherwise specified)
Parameter
Input Quiescent Current
Input Shutdown Current
RT9715A/B
Symbol
IQ
Test Conditions
Min
Typ
Max
Unit
Switch On, VOUT = Open
Switch Off, VOUT = Open
VIN = 5V, IOUT = 1.5A
VIN = 5V, IOUT =1.3A
VIN = 5V, IOUT = 1A
--
--
--
--
--
--
50
0.1
90
90
90
90
70
1
uA
ISHDN
110
110
110
110
RT9715C/D
RT9715E/F
RT9715G/H
Switch On
Resistance
RDS(ON)
mΩ
V
IN = 5V, IOUT = 0.6A
RT9715A/B
RT9715C/D
RT9715E/F
RT9715G/H
RT9715A/B
RT9715C/D
RT9715E/F
RT9715G/H
2
1.5
1.1
0.7
--
2.5
2
3.2
2.8
2.1
1.4
--
Current
Limit
ILIM
VOUT = 4V
A
A
1.5
1
1.7
1.4
1
Short
Current
VOUT = 0V, Measured Prior to
Thermal Shutdown
--
--
ISC_FB
--
--
--
--
0.7
To be continued
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3
RT9715
Parameter
Symbol
Test Conditions
VIN = 2.7V to 5.5V
Min
2
Typ
--
Max
--
Unit
V
Logic_High Voltage VIH
Logic_Low Voltage VIL
EN/EN
Threshold
VIN = 2.7V to 5.5V
--
--
0.8
0.1
1
V
--
0.01
0.5
200
20
uA
uA
us
Ω
EN/EN Input Current
Output Leakage Current
Output Turn-On Rise Time
FLG Output Resistance
FLG Off Current
IEN/EN
VEN = 5V
ILEAKAGE
--
VEN = 0V, RLOAD = 0Ω
10% to 90% of VOUT Rising
TON_RISE
RFLG
IFLG_OFF
--
--
I
SINK = 1mA
--
--
--
0.01
1
uA
VFLG = 5V
From fault condition to FLG
assertion
FLG Delay Time
TD
5
12
20
ms
VEN = 0V, VEN = 5V
Shutdown Auto-Discharge
Resistance
RDischarge
--
100
150
Ω
Under-Voltage Lockout
VUVLO
VIN Rising
1.3
--
1.7
0.1
120
100
20
--
--
--
--
--
V
V
Under-Voltage Hysteresis
ΔVUVLO
VIN Decreasing
VOUT > 1V
--
°C
°C
°C
Thermal Shutdown Protection
Thermal Shutdown Hysteresis
TSD
VOUT = 0V
--
VOUT = 0V
--
Note 1. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
These are stress ratings only, and 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 affect device reliability.
Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity 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.
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DS9715-03 April 2011
RT9715
Typical Operating Characteristics
On Resistance vs. Input Voltage
On Resistance vs. Temperature
108
125
120
115
110
105
100
95
IOUT = 2A
VIN = 5V, IOUT = 2A
106
SOP-8
104
102
100
98
SOP-8
SOT-23-5
90
96
SOT-23-5
85
94
92
90
80
75
70
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
-40
-25
-10
5
20
35
50
65
80
Input Voltage (V)
(°C)
Temperature
Quiescent Current vs. Input Voltage
Quiescent Current vs. Temperature
60
58
56
54
52
50
48
46
44
42
40
60
59
58
57
56
55
54
53
52
51
50
No Load
VIN = 5V,No Load
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
-40 -25 -10
5
20 35 50 65 80 95 110
Input Voltage (V)
Temperature (°C)
Shutdown Current vs. Input Voltage
Shutdown Current vs. Temperature
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
No Load
VIN = 5V
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
-40 -25 -10
5
20 35 50 65 80 95 110
Input Voltage (V)
Temperature
(°C)
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5
RT9715
UVLO Threshold vs. Temperature
Output Voltage vs. Output Current
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
2.2
2.0
1.8
1.6
1.4
1.2
1.0
VIN = 5V
Rising
Falling
VIN = 3.3V
0
0.25 0.5 0.75
1
1.25 1.5 1.75
2
2.25 2.5
-40 -25 -10
5
20 35 50 65 80 95 110
(°C)
Temperature
Output Current (A)
Current Limit vs. Input Voltage
Current Limit vs. Temperature
2.4
2.3
2.2
2.1
2.0
1.9
1.8
1.7
1.6
2.40
2.35
2.30
2.25
2.20
2.15
2.10
2.05
2.00
VIN = 5V
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
-40 -25 -10
5
20 35 50 65 80 95 110
Input Voltage (V)
Temperature (°C)
Short Current vs. Input Voltage
Short Current vs. Temperature
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
2.00
1.90
1.80
1.70
1.60
1.50
1.40
1.30
1.20
1.10
1.00
VIN = 5V
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
-40 -25 -10
5
20 35 50 65 80 95 110
Input Voltage (V)
Temperature
(°C)
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DS9715-03 April 2011
RT9715
FLG Delay Time vs. Temperature
FLG Delay Time vs. Input Voltage
12.0
11.5
11.0
10.5
10.0
9.5
12
11
10
9
VIN = 5V
8
7
9.0
6
8.5
5
8.0
4
-40 -25 -10
5
20 35 50 65 80 95 110
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Temperature (°C)
Power On from VIN
Power Off from VIN
EN = 0V, No Load
EN = 0V, No Load
VIN
(2V/Div)
VIN
(2V/Div)
VOUT
(2V/Div)
VOUT
(2V/Div)
Time (25ms/Div)
Time (25ms/Div)
FLG Response
Power On from EN
VIN = 5V, RLOAD = 2.7Ω
VOUT
(2V/Div)
VOUT
(2V/Div)
IIN
(1A/Div)
EN
(5V/Div)
EN
(5V/Div)
IIN
(1A/Div)
FLG
(5V/Div)
VIN = 5V, RLOAD = 0.5Ω
Time (2.5ms/Div)
Time (100us/Div)
DS9715-03 April 2011
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7
RT9715
Applications Information
Fault Flag
The RT9715 is a single N-MOSFET high-side power
switches with enable input, optimized for self-powered and
bus-powered Universal Serial Bus (USB) applications. The
RT9715 is equipped with a charge pump circuitry to drive
The RT9715 series provides a FLGsignal pin which is an
N-Channel open drain MOSFET output. This open drain
output goes low when current limit or the die temperature
exceeds 120°C approximately. The FLGoutput is capable
of sinking a 10mA load to typically 200mV above ground.
The FLGpin requires a pull-up resistor, this resistor should
be large in value to reduce energy drain. A100kΩ pull-up
resistor works well for most applications. In the case of an
over-current condition, FLGwill be asserted only after the
flag response delay time, tD, has elapsed. This ensures
that FLGis asserted only upon valid over-current conditions
and that erroneous error reporting is eliminated.
the internal N-MOSFET switch; the switch's low RDS(ON)
,
90mΩ, 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.
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 12ms.
Unlike a normal MOSFET, there is no parasitic body diode
between drain and source of the MOSFET, the RT9715
prevents reverse current flow if VOUT is externally forced to
Under-Voltage Lockout
a higher voltage than VIN when the chip is disabled (VEN
0.8V or VEN > 2V).
<
Under-voltage lockout (UVLO) prevents the MOSFETswitch
from turning on until input the voltage exceeds
approximately 1.7V. If input voltage drops below
approximately 1.3V, UVLO turns off the MOSFET switch.
Under-voltage detection functions only when the switch is
enabled.
S
D
S
D
G
G
Current Limiting and Short-Circuit Protection
Normal MOSFET
RT9715
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 2A
through the switch of the RT9715A/B, 1.5A for
RT9715C/D, 1.1A for RT9715E/F and 0.7A for
RT9715G/H 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 limit threshold is exceeded, the device enters
constant current mode until the thermal shutdown occurs
or the fault is removed.
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 MOSFETwill be turned off, reducing the supply
current to 0.1uA 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.
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.
Thermal Shutdown
Thermal protection limits the power dissipation in RT9715.
When the operation junction temperature exceeds 120°C,
the OTP circuit starts the thermal shutdown function and
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DS9715-03 April 2011
RT9715
turns the pass element off. The pass element turn on again
after the junction temperature cools to 80°C. The RT9715
lowers its OTP trip level from 120°C to 100°C when output
short circuit occurs (VOUT < 1V) as shown in Figure 1.
The junction to ambient thermal resistance (θJA) for
SOT-23-5/TSOT-23-5, SOP-8/MSOP-8 and WDFM-8L3x3
packages at recommended minimum footprint are 250°C/
W, 160°C/W and 108°C/W respectively (θJA is layout
dependent).
V
Short to GND
OUT
Universal Serial Bus (USB) & Power Distribution
1V
V
OUT
The goal of USB is to enable 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 implementation. 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.
I
OUT
Thermal
Shutdown
120°C
100 C
°
OTP Trip Point
100 °C
80 °C
IC Temperature
Figure 1. Short Circuit Thermal Folded Back Protection
when Output Short Circuit Occurs (Patent)
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
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.
Power Dissipation
The junction temperature of the RT9715 series depend on
several factors such as the load, PCB layout, ambient
temperature and package type. The output pin of the
RT9715 can deliver the current of up to 2A (RT9715A/B),
1.5A(RT9715C/D), 1.1A(RT9715E/F) and 0.7A(RT9715G/
H) 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 the switch as below.
ABus-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 100mAfrom 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.
2
PD = RDS(ON) x IOUT
Although the devices are rated for 2A, 1.5A, 1.1Aand 0.7A
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 :
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.
PD (MAX) = ( TJ (MAX) - T ) / θJA
A
Where TJ (MAX) is the maximum junction temperature of
the die (100°C) andTA is the maximum ambient temperature.
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9
RT9715
The faster trip time of the RT9715 power distribution allows
designers to design hubs that can operate through faults.
The RT9715 provides low on-resistance and internal fault-
reporting circuitry to meet voltage regulation and fault
notification requirements.
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) :
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.
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)
Supply Filter/Bypass Capacitor
RCABLE = Resistance of upstream cable wires
(one 5V and one GND)
A1uF low-ESR ceramic capacitor from VIN toGND, 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 6V of the
absolute maximum supply voltage even for a short duration.
RSWITCH = Resistance of power switch
(90mΩ typical for RT9715)
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.
Output Filter Capacitor
A low-ESR 150uF aluminum electrolytic or tantalum
between VOUT andGNDis strongly recommended to meet
the 330mV maximum droop requirement in the hub VBUS
(Per USB 2.0, output ports must have a minimum 120uF
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 0.1uF 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.
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 − V ) ( 0.1A x NPORTS
)
÷
PCB
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 RT9715, with its maximum
100mΩ on-resistance over temperature, can fit the demand
of this requirement.
Thermal Considerations
Voltage Drop
For continuous operation, do not exceed absolute
maximum operation junction temperature. The maximum
power dissipation depends on the thermal resistance of IC
package, PCB layout, the rate of surroundings airflow and
temperature difference between junction to ambient. The
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
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10
DS9715-03 April 2011
RT9715
maximum power dissipation can be calculated by following
formula :
PCB Layout Guide
In order to meet the voltage drop, droop, and EMI
requirements, careful PCB layout is necessary. The
following guidelines must be followed :
PD(MAX) = (TJ(MAX) − TA) / θJA
Where TJ(MAX) is the maximum operation junction
temperature 100°C, TAis the ambient temperature and the
θJA is the junction to ambient thermal resistance.
` Locate the ceramic bypass capacitors as close as
possible to the VIN pins of the RT9715.
` Place a ground plane under all circuitry to lower both
resistance and inductance and improveDC and transient
performance (Use a separate ground and power plans if
possible).
For recommended operating conditions specification of
RT9715, where TJ(MAX) is the maximum junction
temperature of the die (100°C) and TA is the maximum
ambient temperature. The junction to ambient thermal
resistance θJA is layout dependent. For SOT-23-5
packages, the thermal resistance θJA is 250°C/W on the
standard JEDEC 51-3 single-layer thermal test board.And
for SOP-8 and MSOP-8 packages, the thermal resistance
` Keep all VBUS traces as short as possible and use at
least 50-mil, 2 ounce copper for all VBUS traces.
` Avoid vias as much as possible. If vias are necessary,
make them as large as feasible.
θJA is 160°C/W. The maximum power dissipation at TA =
` Place cuts in the ground plane between ports to help
25°C can be calculated by following formula :
reduce the coupling of transients between ports.
PD(MAX) = (100°C - 25°C) / (250°C/W) = 0.3W for
` Locate the output capacitor and ferrite beads as close to
the USB connectors as possible to lower impedance
(mainly inductance) between the port and the capacitor
and improve transient load performance.
SOT-23-5 packages
PD(MAX) = (100°C - 25°C) / (160°C/W) = 0.469W for
SOP-8/MSOP-8 packages
PD(MAX) = (100°C - 25°C) / (108°C/W) = 0.694W for
WDFN-8L 3x3 packages
` Locate the RT9715 as close as possible to the output
port to limit switching noise.
The maximum power dissipation depends on operating
ambient temperature for fixedTJ(MAX) and thermal resistance
θJA. For RT9715 packages, the Figure 2 of derating curves
allows the designer to see the effect of rising ambient
temperature on the maximum power allowed.
The input capacitor should
be placed as close as
possible to the IC.
V
V
V
BUS
OUT
IN
0.8
Single Layer PCB
WDFN-8L 3x3
GND
0.7
0.6
SOP-8/MSOP-8
0.5
GND_BUS
EN
FLG
0.4
SOT-23-5
0.3
V
IN
Figure 3
0.2
0.1
0
0
10 20 30 40 50 60 70 80 90 100
Ambient Temperature (°C)
Figure 2. Derating Curves for RT9715 Package
DS9715-03 April 2011
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11
RT9715
Outline Dimension
H
D
L
B
C
A
b
A1
e
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
A1
B
0.889
0.000
1.397
0.356
2.591
2.692
0.838
0.080
0.300
1.295
0.152
1.803
0.559
2.997
3.099
1.041
0.254
0.610
0.035
0.000
0.055
0.014
0.102
0.106
0.033
0.003
0.012
0.051
0.006
0.071
0.022
0.118
0.122
0.041
0.010
0.024
b
C
D
e
H
L
SOT-23-5 Surface Mount Package
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12
DS9715-03 April 2011
RT9715
H
A
M
J
B
F
C
I
D
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
B
C
D
F
H
I
4.801
3.810
1.346
0.330
1.194
0.170
0.050
5.791
0.400
5.004
3.988
1.753
0.508
1.346
0.254
0.254
6.200
1.270
0.189
0.150
0.053
0.013
0.047
0.007
0.002
0.228
0.016
0.197
0.157
0.069
0.020
0.053
0.010
0.010
0.244
0.050
J
M
8-Lead SOP Plastic Package
DS9715-03 April 2011
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13
RT9715
D
L
E
E1
e
A2
A
A1
b
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
A1
A2
b
0.810
0.000
0.750
0.220
2.900
1.100
0.150
0.950
0.380
3.100
0.032
0.000
0.030
0.009
0.114
0.043
0.006
0.037
0.015
0.122
D
e
0.650
0.026
E
4.800
2.900
0.400
5.000
3.100
0.800
0.189
0.114
0.016
0.197
0.122
0.031
E1
L
8-Lead MSOP Plastic Package
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DS9715-03 April 2011
RT9715
D2
D
L
E
E2
SEE DETAIL A
1
e
b
2
1
2
1
A
A3
DETAILA
Pin #1 ID and Tie Bar Mark Options
A1
Note : The configuration of the Pin #1 identifier is optional,
but must be located within the zone indicated.
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
A1
A3
b
0.700
0.000
0.175
0.200
2.950
2.100
2.950
1.350
0.800
0.050
0.250
0.300
3.050
2.350
3.050
1.600
0.028
0.000
0.007
0.008
0.116
0.083
0.116
0.053
0.031
0.002
0.010
0.012
0.120
0.093
0.120
0.063
D
D2
E
E2
e
0.650
0.026
L
0.425
0.525
0.017
0.021
W-Type 8L DFN 3x3 Package
Richtek Technology Corporation
Headquarter
Richtek Technology Corporation
Taipei Office (Marketing)
5F, No. 20, Taiyuen Street, Chupei City
Hsinchu, Taiwan, R.O.C.
5F, No. 95, Minchiuan Road, Hsintien City
Taipei County, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Tel: (8862)86672399 Fax: (8862)86672377
Email: marketing@richtek.com
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.
DS9715-03 April 2011
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15
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