DS9722 00

RT9722
145mΩ
Ω, 1.5A Power Switch with Programmable Current Limit
General Description
Features
The RT9722 is a cost effective, low voltage, single
P-MOSFET high side power switch IC. Typical 145mΩ
switch on resistance and 10μA quiescent current are
realized in this IC. In order to fit different application, a
SET pin is offered for current limit point setting, a resistor
from SET to Ground sets the current limit for this switch.
z
In addition, the RT9722 integrates a thermal shutdown
circuit and under voltage lockout circuit for overall
protection, and a FLAG output with delay is available to
indicate fault conditions to the local controller.
The RT9722 is an ideal solution for high side power load
switch and can support flexible applications since it is
available in various package such as WDFN-6L 2x2,
SOT-23-5 and SOT-23-6.
Ordering Information
RT9722
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Programmable Current Limit : 0.2A to 1.5A
Low Quiescent Current : 10μ
μA
Low Shutdown Current : 0.1μ
μA
145mΩ
Ω Switch On Resistance
Operating Voltage Range : 2.4V to 5.5V
Under Voltage Lockout
Thermal Shutdown Protection
RoHS Compliant and Halogen Free
Applications
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Handheld Devices
Hot Swap Supplies
Notebooks
Peripheral Ports
Personal Communication Devices
Pin Configurations
Package Type
B : SOT-23-5
E : SOT-23-6
QW : WDFN-6L 2x2 (W-Type)
(TOP VIEW)
VIN
EN/EN
5
4
Lead Plating System
G : Green (Halogen Free and Pb Free)
EN Function
A : Active High
B : Active Low
Note :
2
VOUT GND SET
SOT-23-5
VIN FLG EN/EN
Richtek products are :
`
6
5
4
2
3
RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
`
3
Suitable for use in SnPb or Pb-free soldering processes.
VOUT GND SET
SET
1
VIN
VOUT
2
GND
SOT-23-6
3
7
5
EN/EN
NC
4
FLG
6
WDFN-6L 2x2
DS9722-00 August 2011
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1
RT9722
Marking Information
RT9722BGB
RT9722AGB
1H= : Product Code
1H=DNN
1S= : Product Code
1S=DNN
DNN : Date Code
DNN : Date Code
RT9722BGE
RT9722AGE
DQ= : Product Code
DQ=DNN
DT= : Product Code
DT=DNN
DNN : Date Code
RT9722BGQW
RT9722AGQW
H0 : Product Code
H1 : Product Code
W : Date Code
H0W
DNN : Date Code
W : Date Code
H1W
Typical Application Circuit
Pull-Up Resistor (10k to 100k)
Supply
Voltage
5 VIN
CIN
1µF
Enable
SET
3
RT9722
4 EN/EN
RSET
VIN
CIN
1µF
Fault Flag
FLG
RT9722
SET
RSET
VOUT 1
GND
2
0.47µF Peripheral
Figure 1. Typical Application Circuit for SOT-23-5
Package
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2
Supply
Voltage
Enable
EN/EN VOUT
GND
0.47µF Peripheral
Figure 2. Typical Application Circuit for SOT-23-6 and
WDFN-6L 2x2 Package
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RT9722
Functional Pin Description
Pin No.
Pin Name
Pin Function
SOT-23-5
SOT-23-6
WDFN-6L 2x2
1
1
3
2
2
3
3
1
SET
Current Limit Set Input. A resistor from SET to GND sets
the current limit of the switch.
4
4
6
EN/EN
Chip Enable (Active High for RT9722A / Active Low for
RT9722B).
--
5
4
FLG
Fault Flag Open-Drain Output.
5
6
2
VIN
Power Input Voltage.
--
--
5
NC
No Internal Connection.
VOUT
7 (Exposed Pad) GND
Switch Output Voltage.
Ground. The exposed pad must be soldered to a large PCB
and connected to GND for maximum power dissipation.
Function Block Diagram
SET
VIN
Current
Limiting
UVLO
EN/EN
Bias
Thermal
Protection
Gate
Control
Output
Voltage
Detection
VOUT
FLG
Flag
Control
GND
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RT9722
Absolute Maximum Ratings
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(Note 1)
Supply Input Voltage, VIN ------------------------------------------------------------------------------------------------ 6V
EN Voltage ------------------------------------------------------------------------------------------------------------------ −0.3V to 6V
FLAG, SET Voltage ------------------------------------------------------------------------------------------------------- 6V
Power Dissipation, PD @ TA = 25°C
SOT-23-5/SOT-23-6 ------------------------------------------------------------------------------------------------------WDFN-6L 2x2 -------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2)
SOT-23-5/SOT-23-6 ------------------------------------------------------------------------------------------------------WDFN-6L 2x2, θJA --------------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3)
HBM -------------------------------------------------------------------------------------------------------------------------MM ----------------------------------------------------------------------------------------------------------------------------
Recommended Operating Conditions
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0.4W
0.606W
250°C/W
165°C/W
260°C
150°C
−65°C to 150°C
2kV
200V
(Note 4)
Supply Input Voltage, VIN -----------------------------------------------------------------------------------------------EN Voltage -----------------------------------------------------------------------------------------------------------------Junction Temperature Range -------------------------------------------------------------------------------------------Ambient Temperature Range --------------------------------------------------------------------------------------------
2.4V to 5.5V
0V to 5.5V
−40°C to 125°C
−40°C to 85°C
Electrical Characteristics
(VIN = 5V, CIN = 1μF, COUT = 0.47μF, TA = 25°C, unless otherwise specified)
Parameter
Symbol
Test Conditions
VIN = 5V, RSET = 20kΩ,
IOUT = 100mA
EN = Active, SET Pin Open,
IOUT = 0
EN = Inactive, VOUT = Open
Min
Typ
Max
Unit
--
145
180
mΩ
--
10
25
μA
--
0.1
1
μA
Switch On Resistance
R DS(ON)
Quiescent Current
IQ
Shutdown Current
I SHDN
EN/EN Threshold Logic-Low
Voltage
Logic-High
VIL
--
--
0.6
VIH
1.4
--
--
EN/EN Input Current
I EN/EN
VEN/EN = 5V
--
0.01
0.1
μA
Output Leakage Current
I LEAKAGE
Switch Off, VOUT = 0V
--
0.01
1
μA
Turn On Time
t ON
VIN = 5V, RLOAD = 10Ω
--
12
200
μs
Turn Off Time
t OFF
VIN = 5V, RLOAD = 10Ω
--
10
--
μs
Current Limit
I LIM
RSET = 6.8kΩ, VOUT = 4V
0.75
1
1.25
A
Minimum Current Limit
I LIM(MIN)
--
0.2
--
A
Current Limit Response Time
t Response
--
10
--
μs
RLOAD = 0Ω
V
To be continued
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RT9722
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
FLG Output Resistance
RFLG
ISINK = 1mA
--
20
--
Ω
FLG Off Current
IFLG_Off
VFLG = 5V
--
0.01
1
μA
FLG Delay Time
tD
From Fault Condition to FLG
Assertion
5
12
20
ms
Under Voltage Lockout
Threshold
VUVLO
VIN Increasing
--
2
2.4
V
Under Voltage Hysteresis
ΔVUVLO
VIN Increasing
--
0.1
--
V
Thermal Shutdown Protection
TSD
--
150
--
°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.
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RT9722
Typical Operating Characteristics
Supply Current vs. Temperature
Supply Current vs. Input Voltage
20
RSET = Open, RLOAD = Open
18
VIN = 5V, RSET = Open, RLOAD = Open
18
16
16
Supply Current (μA)
Supply Current (μA)
20
14
12
10
8
6
4
2
14
12
10
8
6
4
2
0
0
2.5
3
3.5
4
4.5
5
5.5
-50
-25
0
Input Voltage (V)
VIN = 5V, EN = 0V, RSET = 6.8kΩ, RLOAD = Open
100
125
VIN = 5V, RSET = 16kΩ
500
0.8
Output Current (mA)
Shutdown Current (μA)1
75
Output Current vs. Output Voltage
600
0.6
0.4
0.2
400
300
200
100
0
0
-50
-25
0
25
50
75
100
125
0
1
Temperature (°C)
2
3
4
5
Output Voltage (V)
RDS(ON) vs. Input Voltage
250
RDS(ON) vs. Temperature
300
RSET = 16kΩ, ILOAD = 100mA
RSET = 16kΩ, ILOAD = 100mA
250
RDS(ON) (mΩ)
200
RDS(ON) (mΩ)
50
Temperature (°C)
Shutdown Current vs. Temperature
1
25
150
100
50
VIN = 3V
200
150
VIN = 5V
100
50
0
0
2.5
3
3.5
4
4.5
Input Voltage (V)
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5
5.5
-50
-25
0
25
50
75
100
125
Temperature (°C)
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RT9722
UVLO Threshold Voltage vs. Temperature
EN Threshold Voltage vs. Input Voltage
1.4
2.6
Rising
1.8
1.6
1.4
EN Threshold Voltage (V)
UVLO Threshold Voltage (V)
2.4
2.2
2.0
Falling
1.2
1.0
0.8
0.6
0.4
0.2
VIN = 5V, RSET = 16kΩ, RLOAD = 510Ω
0.0
-50
-25
0
25
50
75
100
1.2
V IH
1.0
VIL
0.8
0.6
0.4
0.2
RSET = 16kΩ, RLOAD = 510Ω
0.0
2.5
125
3
3.5
Current Limit vs. RSET
5.5
Flag Delay Time vs. Input Voltage
VIN = 5V, RLOAD = 1Ω
12
1200
Flag Delay Time (ms)
Current Limit (mA)
5
14
1400
1000
800
600
400
10
8
6
4
200
2
0
0
0
10
20
30
40
50
60
70
VIN = 5V, RSET = 6.8kΩ, RLOAD = 0Ω, COUT = 0.47μF
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
RSET (kΩ)
Turn-Off Time vs. Temperature
Turn-On Time vs. Temperature
12
30
25
10
VIN = 3V
Turn-Off Time (μs)
Turn-On Time (μs)
4.5
Input Voltage (V)
Temperature (°C)
1600
4
20
VIN = 5V
15
10
VIN = 5V
8
6
VIN = 3V
4
2
5
RSET = 6.8kΩ, RLOAD = 10Ω, COUT = 0.47μF
0
-50
-25
0
25
50
Temperature (°C)
DS9722-00 August 2011
75
100
125
RSET = 6.8kΩ, RLOAD = 10Ω, COUT = 0.47μF
0
-50
-25
0
25
50
75
100
125
Temperature (°C)
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RT9722
Power Off from EN
Power On from EN
VEN
(5V/Div)
VEN
(5V/Div)
VOUT
(2V/Div)
VOUT
(2V/Div)
IOUT
(200mA/Div)
IOUT
(200mA/Div)
VIN = 5V, RSET = 6.8kΩ, RLOAD = 10Ω, COUT = 0.47μF
VIN = 5V, RSET = 6.8kΩ, RLOAD = 10Ω, COUT = 0.47μF
Time (25μs/Div)
Time (10μs/Div)
Current Limit with Thermal Shutdown
VIN
(5V/Div)
VOUT
(1V/Div)
VIN
(5V/Div)
VOUT
(5V/Div)
Flag
(5V/Div)
Flag
(5V/Div)
IOUT
(500mA/Div)
Short Circuit Protection
IOUT
(500mA/Div)
VIN = 5V, RSET = 16kΩ, RLOAD = 1Ω, COUT = 0.47μF
VIN = 5V, RSET = 6.8kΩ, RLOAD = 0Ω, COUT = 0.47μF
Time (250ms/Div)
Time (25ms/Div)
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RT9722
Application Information
The RT9722 is a high-side power switch with programmable
current limit function. The RT9722 provides active-high
(RT9722A) and active-low (RT9722B) enable input and full
protection functions make it optimized to replace complex
discrete on/off control circuitry.
Table 1. Current Limit vs. RSET Resistance
Design Current Limit (mA)
RSET (kΩ)
Min
Typ
Max
4.7
1125.0
1500
1875.0
5.49
937.5
1250
1562.5
Current Limit Setting
6.8
750.0
1000
1250.0
The current limit value ILIM, can be set by an external
resistor between SET and GND. Figure 3 shows the typical
current limit value under various setting resistance, RSET.
7.32
675.0
900
1125.0
8.66
600.0
800
1000.0
10.5
525.0
700
875.0
13
450.0
600
750.0
16
375.0
500
625.0
18
337.5
450
562.5
Current Limit vs. RSET
1600
Current Limit (mA)
1400
1200
20
300.0
400
500.0
1000
22.6
262.5
350
437.5
800
30
225.0
300
375.0
600
34.8
187.5
250
312.5
400
47
150.0
200
250.0
200
Chip Enable Input
0
A few standard resistor values of the RSET and its typical
current limit set point with ±25% tolerance are listed in
Table 1.
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 typically. The maximum guaranteed
voltage for a logic low at the EN pin is 0.6V. A minimum
guaranteed voltage of 1.4V at the EN pin will turn on the
RT9722 again. Floating the input may cause unpredictable
operation. EN should not be allowed to go negative with
respect to GND. The EN pin can be directly tied to VIN to
keep the part on.
Input and Output
Soft-Start for Hot Plug-In Applications
VIN (input) is the power source connected to the internal
circuitry and the source of the MOSFET. VOUT (output) is
the drain 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. The
RT9722 is designed to control current flowing from VIN to
VOUT. If a voltage applied to VOUT is greater than the voltage
on VIN, large currents may flow and cause damage to the
device.
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.
0
10
20
30
40
50
60
70
(kΩ)
RSET (kΩ)
Figure 3. Current Limit vs. RSET Resistance
The accuracy of current limit set point may vary with
operating temperature and supply voltage, see “Typical
Operating Characteristics” graph for further details.
DS9722-00 August 2011
Fault Flag
The RT9722 provides a FLG signal pin which is an
N-Channel open drain MOSFET output. This open drain
output goes low when current limit VOUT < VIN − 1V, or the
die temperature exceeds 150°C approximately. The FLG
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RT9722
pin requires a pull-up resistor, this resistor should be large
in value to reduce energy drain. A 100k pull-up resistor
works well for most applications. In the case of an overcurrent 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 a highly large capacitive load
is connected and causes a high transient inrush current
that exceeds the current limit threshold. The FLG response
delay time tD is typically 12ms at VIN = 5V.
Under-Voltage Lockout
Under-voltage lockout (UVLO) prevents the MOSFET
switch from turning on until input voltage exceeds
approximately 2V. Under-voltage detection functions only
when the chip enable input is enabled.
Thermal Shutdown
Thermal shutdown is employed to protect the device from
damage if the die temperature exceeds approximately
150°C. If enabled, the switch automatically restarts when
the die temperature falls 20°C (typ.). The output will
continue to cycle on and off until the device is disabled or
the fault is removed.
Short Circuit Protection
The current limit circuitry prevents damage to the MOSFET
switch and external load. 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
occurred or the fault is removed.
Supply Filter/Bypass Capacitor
A 1μF low-ESR ceramic capacitor from VIN to GND (the
amount of the capacitance may be increased without limit),
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
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control circuitry. An important note to be award of is the
parasitic inductance of PCB traces can cause over-voltage
transients if the PCB trace has even a few tens of nH of
inductance. The input transient must not exceed 6.0V of
the absolute maximum supply voltage even for a short
duration.
Power Dissipation
The device's junction temperature depends on several
factors such as the load, PCB layout, ambient temperature
and package type. The maximum output current must be
derated at higher ambient temperature to ensure the
junction temperature does not exceed operating junction
temperature 125°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
The application may limit the amount of output current
based on the total power dissipation and the ambient
temperature.
Thermal Considerations
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 maximum power dissipation can
be calculated by following formula :
PD(MAX) = (TJ(MAX) − TA) / θJA
Where T J(MAX) is the maximum operation junction
temperature, TA is the ambient temperature and the θJA is
the junction to ambient thermal resistance.
For recommended operating conditions specification of
RT9722, the maximum operating junction temperature is
125°C. The junction to ambient thermal resistance θJA for
SOT-23-5/SOT-23-6 package is 250°C/W and WDFN-6L
2x2 package is 165°C/W on the standard JEDEC 51-3
single-layer thermal test board. The maximum power
dissipation at TA = 25°C can be calculated by following
formula :
P D(MAX) = (125°C − 25°C) / (250°C/W) = 0.4W for
SOT-23-5/SOT-23-6 package
DS9722-00 August 2011
RT9722
PD(MAX) = (125°C − 25°C) / (165°C/W) = 0.606W for
WDFN-6L 2x2 package
The maximum power dissipation depends on operating
ambient temperature for fixed T J(MAX) and thermal
resistance θJA. For the RT9722 Figure 4 shows the
maximum power dissipation allowed under various ambient
temperatures.
0.70
Power Dissipation (W)
For the best performance of the RT9722, careful PCB
layout is necessary. The following guidelines must be
considered:
`
Keep all input and output traces as short and wide as
possible.
`
Locate the bypass capacitors as close as possible to
the input and output pin of the RT9722.
`
Avoid vias as much as possible. If vias are necessary,
make them as large as feasible.
`
Place a ground plane under all circuitry to lower both
resistance and inductance and improve DC and transient
performance (Use a separate ground and power plane if
possible).
Single Layer PCB
0.60
WDFN-6L 2x2
0.50
0.40
0.30
Layout Consideration
SOT-23-5/SOT-23-6
0.20
CIN R
pull-up
0.10
0.00
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 4. RT9722 Maximum Power Dissipation Derating
Curve
The main current
trace should be
as possible as
short and wide.
VIN FLG EN/EN
6
5
4
2
3
VOUT GND SET
The input and output
capacitors should be
placed as close as
possible to the IC.
COUT RSET
Figure 5. PCB Layout Guide
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RT9722
Outline Dimension
H
D
L
B
C
b
A
A1
e
Symbol
Dimensions In Millimeters
Dimensions In Inches
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
SOT-23-5 Surface Mount Package
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DS9722-00 August 2011
RT9722
H
D
L
C
B
b
A
A1
e
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
0.889
1.295
0.031
0.051
A1
0.000
0.152
0.000
0.006
B
1.397
1.803
0.055
0.071
b
0.250
0.560
0.010
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
SOT-23-6 Surface Mount Package
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RT9722
D2
D
L
E
E2
1
2
e
1
2
1
b
A
A1
SEE DETAIL A
DETAIL A
Pin #1 ID and Tie Bar Mark Options
A3
Note : The configuration of the Pin #1 identifier is optional,
but must be located within the zone indicated.
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
0.700
0.800
0.028
0.031
A1
0.000
0.050
0.000
0.002
A3
0.175
0.250
0.007
0.010
b
0.200
0.350
0.008
0.014
D
1.950
2.050
0.077
0.081
D2
1.000
1.450
0.039
0.057
E
1.950
2.050
0.077
0.081
E2
0.500
0.850
0.020
0.033
e
L
0.650
0.300
0.026
0.400
0.012
0.016
W-Type 6L DFN 2x2 Package
Richtek Technology Corporation
Richtek Technology Corporation
Headquarter
Taipei Office (Marketing)
5F, No. 20, Taiyuen Street, Chupei City
5F, No. 95, Minchiuan Road, Hsintien City
Hsinchu, Taiwan, R.O.C.
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.
www.richtek.com
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DS9722-00 August 2011