RT9727A
N-MOSFET Load Switch Controller
General Description
Features
The RT9727A is a load switch controller to control the
external N-MOSFET load switch. The input voltage range
of the RT9727A is from 6V to 25V. The RT9727A adopts
the constant power discharge method to discharge the
residual storages. Besides, the RT9727A also provides
enable control function and over temperature protection
function.
z
Driver N-MOSFET Load Switch
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Input Voltage Range : 6V to 25V
Constant Power Discharge
Over Temperature Protection
Enable Control
RoHS Compliant and Halogen Free
The RT9727A is available in a SC-70-6 package.
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z
z
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Applications
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Notebook Computers
Ordering Information
RT9727A
Pin Configurations
Package Type
U6 : SC-70-6
Lead Plating System
G : Green (Halogen Free and Pb Free)
(TOP VIEW)
EN
DC2
DC1
6
5
4
2
3
GND
CT
Note :
Richtek products are :
`
VCC
RoHS compliant and compatible with the current require-
SC-70-6
ments of IPC/JEDEC J-STD-020.
`
Suitable for use in SnPb or Pb-free soldering processes.
Typical Application Circuit
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
5V Source
1
VCC
VCC
C1
Chip Enable
CT 3
DC2 5
Q1
To Systrm
C3
RT9727A
6 EN
2 GND
DC1
4
To Systrm
C2
DS9727A-01 April 2011
3V Source
Q2
C4
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RT9727A
Function Block Diagram
VCC
Regulator
EN
Bias
CT
Thermal
Protection
Gate
Control
DC2
Gate
Control
DC1
GND
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
VCC
Power Supply Input.
2
GND
Ground.
3
CT
Current Source Output. There is an internal 10μA current source from VCC to CT.
4
DC1
Discharge Path when EN Pulls Low.
5
DC2
Discharge Path when EN Pulls Low.
6
EN
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2
Chip Enable (Active High). Enable Control of the Internal 10μA current source and DCx
discharge.
DS9727A-01 April 2011
RT9727A
Absolute Maximum Ratings
z
z
z
z
z
z
z
z
(Note 1)
VCC, CT to GND ----------------------------------------------------------------------------------------------------------EN, DC1, DC2 to GND ---------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C
SC-70-6 ---------------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2)
SC-70-6, θJA ---------------------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3)
HBM (Human Body Mode) ---------------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------------
Recommended Operating Conditions
z
z
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−0.3V to 28V
−0.3V to 6V
0.3W
333°C/W
260°C
150°C
−65°C to 150°C
2kV
200V
(Note 4)
Supply Input Voltage, VCC ----------------------------------------------------------------------------------------------- 6V to 25V
Junction Temperature Range -------------------------------------------------------------------------------------------Ambient Temperature Range --------------------------------------------------------------------------------------------
−40°C to 125°C
−40°C to 85°C
Electrical Characteristics
(VCC = 10V, VEN = 5V, TA = 25°C, unless otherwise specified)
Parameter
Symbol
Shutdown Current
ISHDN
Test Conditions
VCC = 6V to 25V, EN = Low,
DC1 and DC2 = 0
Quiescent Current
IQ
VCC = 6V to 25V, EN = High
Power On Reset Threshold
VCCR_TH
VCC Rising
Power On Reset Hysteresis
VCC_hys
Min
Typ
Max
Unit
--
5
10
μA
--
40
65
μA
3.8
4.2
4.6
V
--
0.25
--
V
CT Output
CT Source Current
ICTsr
EN = High, CT = 0V
7
10
13
μA
CT Sink Current
ICTsk
EN = Low, CT = 0.5V
200
--
--
μA
EN = Low, DCx = 5V
18
--
--
EN = Low, DCx = 3.3V
20
--
--
EN = Low, DCx = 1.6V
50
--
--
Discharge Current
Discharge Current
IDCx
mA
Thermal Shutdown
Thermal Shutdown
tSHDN
--
160
--
°C
Thermal Shutdown Hysteresis
tSHDN_hys
--
20
--
°C
Rising
2.4
--
--
Falling
--
--
0.8
Logic Input
EN Threshold
Voltage
Logic-High
Logic-Low
DS9727A-01 April 2011
VIH
VIL
V
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RT9727A
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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DS9727A-01 April 2011
RT9727A
Typical Operating Characteristics
Quiescent Current vs. Input Voltage
Shutdown Current vs. Input Voltage
10
Shutdown Current (μA)1
Quiescent Current (μA)
50
48
46
44
42
VEN = 5V
40
5
7
9
11
13
15
17
19
21
23
8
6
4
2
VEN = 0.5V
0
5
25
7
9
11
17
19
21
23
25
Shutdown Current vs. Temperature
Quiescent Current vs. Temperature
60
10
Shutdown Current (μA)1
Quiescent Current (μA)
15
Input Voltage (V)
Input Voltage (V)
55
VCC = 25V
50
VCC = 6V
45
40
VEN = 5V
35
-50
-25
0
25
50
75
100
8
6
VCC = 25V
VCC = 6V
4
2
VEN = 0.5V
0
125
-50
-25
0
Temperature (°C)
25
50
75
100
125
Temperature (°C)
CT Sink Current vs. Input Voltage
CT Source Current vs. Input Voltage
13
147.0
CT Sink Current (μA)
12
CT Source Current (μA)
13
11
10
9
8
146.6
146.2
145.8
145.4
VEN = 5V
7
VEN = 0V, VCT = 0.5V
145.0
5
7
9
11
13
15
17
19
Input Voltage (V)
DS9727A-01 April 2011
21
23
25
5
7
9
11
13
15
17
19
21
23
25
Input Voltage (V)
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RT9727A
CT Source Current vs. Temperature
CT Sink Current vs. Temperature
13
200
180
CT Sink Current (μA)
CT Source Current (μA)
VCC = 25V
12
11
VCC = 6V
10
9
8
160
VCC = 25V
140
VCC = 6V
120
100
VEN = 5V
7
-50
-25
0
25
50
75
100
VEN = 0V, VCT = 0.5V
80
125
-50
-25
0
Temperature (°C)
Discharge Current vs. Temperature
50
75
100
125
VDCx Discharge Characteristic
6
70
System Residual Voltage (V)1
80
Discharge Current (mA)
25
Temperature (°C)
VDCx = 1.6V
60
50
40
VDCx = 3.3V
30
VDCx = 5V
20
10
VEN = 0V
0
-50
-25
0
25
50
75
100
125
5
4
3
2
1
COUT = 300μF
0
0
20
40
60
80
100
Time (ms)
Temperature (°C)
Discharge Current vs. System Residual Voltage
VDCx Discharge Current (mA)
70
60
50
40
30
20
10
VEN = 0V, COUT = 300μF
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
System Residual Voltage (V)
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DS9727A-01 April 2011
RT9727A
Applications Information
Enable & POR
Power-On reset (POR) occurs when the input voltage rises
above to approximately 4.5V, the RT9727A will be turned
on once the EN pin voltage is higher than 2.4V. After the
RT9727A is turned on, there is 10μA (typ.) current flows
from CT pin to the gate of the external MOSFET, while
both DCx pin discharge MOSFET are off.
Discharge Operation
When EN is low, the RT9727A will discharge the system
residual voltage using internal MOSFET connected
between the DCx and GND, while CT pin is pulled low.
The discharge current depends on the voltage at the DCx
pin. While both of the voltages at the DC1 and DC2 pins
are lower than 0.5V, the RT9727A will fully turn the internal
MOSFET on to pull the DCx pins low.
Thermal Protection
The RT9727A provides thermal shutdown detection to
protect the device from over-heating in discharge mode.
Once the junction temperature reaches 160°C, the
RT9727A will stop discharging until the junction
temperature is recovered.
Thermal Considerations
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 maximum power dissipation can be calculated by
following formula :
DS9727A-01 April 2011
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 condition specification of
RT9727A, the maximum junction temperature is 125°C
and TA is the maximum ambient temperature. The junction
to ambient thermal resistance θJA is layout dependent.
For SC-70-6 packages, the thermal resistance θJA is
333°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 :
PD(MAX) = (125°C − 25°C) / (333°C /W) = 0.3W for
SC-70-6 package
The maximum power dissipation depends on operating
ambient temperature for fixed T J(MAX) and thermal
resistance θJA . For RT9727A package, the Figure 1 of
derating curves allows the designer to see the effect of
rising ambient temperature on the maximum power
dissipation allowed.
0.40
Maximum Power Dissipation (W)1
The RT9727A is a load switch with wide input voltage range
from 6V to 25V. It provides two paths for discharging the
residual voltage when system shutdown. Besides, the
external MOSFET switch On/Off can be controlled by an
internal current source from the CT pin to the gate of the
MOSFET switch. A novel control is implemented for nearly
constant power to discharge the system residual voltages.
Single Layer PCB
0.35
0.30
0.25
SC-70-6
0.20
0.15
0.10
0.05
0.00
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 1. Derating Curves for RT9727A Package
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RT9727A
Layout Consideration
For best performance of the RT9727A, the following
guidelines must be followed :
`
Input capacitor should be placed close to the IC and
connected to ground plane to reduce noise coupling.
`
Keep the main current traces as short and wide as
possible.
The input capacitor should be placed
as close as possible to the IC.
VCC
6
EN
CIN
GND
2
5
DC2
CT
3
4
DC1
The main current trace should be as
short and wide as possible.
Figure 2. PCB Layout Guide
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DS9727A-01 April 2011
RT9727A
Outline Dimension
H
D
L
C
B
b
A
A1
e
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
0.800
1.100
0.031
0.044
A1
0.000
0.100
0.000
0.004
B
1.150
1.350
0.045
0.054
b
0.150
0.400
0.006
0.016
C
1.800
2.450
0.071
0.096
D
1.800
2.250
0.071
0.089
e
0.650
0.026
H
0.080
0.260
0.003
0.010
L
0.210
0.460
0.008
0.018
SC-70-6 Surface Mount 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.
DS9727A-01 April 2011
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