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RT9701
100mΩΩΩΩ Power Distribution Switches
General Description
The RT9701 is an integrated 100mΩ power switch
for self-powered and bus-powered Universal Series
Bus (USB) applications. A built-in charge pump is
used to drive the N-channel NMOSFET that is free
of parasitic body diode to eliminate any reversed
current flow across the switch when it is powered
off. Its low quiescent supply current (23µA) and
small package (SOT-25) is particularly suitable in
battery-powered portable equipment.
Several protection functions include soft start to limit
inrush current during plug-in, current limiting at 1.5A
to meet USB power requirement, and thermal
shutdown to protect damage under over current
conditions.
Applications
Battery-Powered Equipment
z
Motherboard USB Power Switch
z
USB Device Power Switch
z
Hot-Plug Power Supplies
z
Battery-Charger Circuits
z
Ordering Information
RT9701-
Package type
BL : SOT-25, w/o CE
B : SOT-25, with CE
X : SOT-89
Operating temperature range
C: Commercial standard
Marking Infromation
Features
z
100mΩΩΩΩ Typ. High-Side NMOSFET (SOT- 25)
Guaranteed 1.1A Continuous Current
z
1.5A Current Limit
z
Small SOT- 25 Package Minimizes Board Space
z
Soft Start
z
Thermal Protection
z
Low 23µµµµA Supply Current
z
Wide Input Voltage Range: 2.2V ~ 6V
z
Pin Configurations
Part Number Pin Configurations
RT9701-CBL
(SOT-25)
RT9701-CB
(SOT-25)
RT9701-CX
(SOT-89)
54
TOP VIEW
321
54
TOP VIEW
321
TOP VIEW
123
1. VOUT
2. GND
3. VIN
4. VIN
5. VOUT
1. VOUT
2. GND
3. VIN
4. CE
5. VOUT
1. VIN
2. GND
3. VOUT
Typical Application Circuit
RT9701 CBL
V
IN
C
IN
1 µF
VIN
VIN
GND
VOUT
VOUT
C
OUT
33 µF
V
OUT
Part Number Marking
RT9701-CBL AH
RT9701-CB C0
RT9701-CX AR
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RT9701
Pin Description
Pin Name Pin Function
VIN Input Pin
VOUT Output Pin
GND Power Ground Pin
CE Chip Enable Control Pin
Test Circuit
IN
V
CE
VINV
CE
GND
Function Block Diagram
CE
Bias
Charge
Pump
Oscillator
VOUT
Control
Thermal
Detection
R
L
Current
Limit
V
C
L
NMOSFET
OUT
RS
VIN
(VIN)
(VOUT)
VOUT
GND
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Absolute Maximum Ratings
)
RT9701
z Supply Voltage V
z Chip Enable V
z Power Dissipation
7V
IN
CE
-0.3V ~ 7V
SOT-25 0.25W
SOT-89 0.5W
z Operating Junction Temperature Range -20°C ~ 100°C
z Storage Temperature Range -65°C ~ 150°C
z Thermal Resistance
SOT-25 θ
SOT-89 θ
z V
OUT
JA
100°C /W
JA
EDS Level
250°C /W
HBM (Human Body Mode) 8KV
MM (Machine Mode) 800V
Electrical Characteristics
(V
= 5V, CIN = C
IN
Input Voltage Range
= 1µF, Ta = 25°C , unless otherwise specified)
OUT
Parameter Symbol Test Conditions Min Typ Max Units
V
IN
2.2 6 V
RT9701-CBL IL = 1A 100 130
Output NMOFET R
DS(ON)
RT9701-CB IL = 1A 105 135
RT9701-CX
R
DS(ON
IL = 1A 110 140
mΩ
VIN = 3V 19 40
Supply Current
Output Turn-On Rising Time
Current Limit Threshold
Short-circuit Output Current
I
DD
T
R
I
LIMIT
I
OS
VIN = 5V 23 45
RL = 10Ω, 90% Settling
RL = 2Ω
V
= 0V 0.5 A
OUT
1.1 1.5 2 A
400
µA
µS
CE Input High Threshold RT9701-CB 2.0 V
V
I
OFF
CE
CE = “0”, V
= 0V 0.5 10
OUT
0.8 V
µA
µA
CE Input Low Threshold RT9701-CB
Shutdown Supply Current RT9701-CBL CE = “0” 0.1 1
Output Leakage Current RT9701-CBL
Under Voltage Lockout UVLO 1.3 1.8 V
Under Voltage Hysteresis 100 mV
Thermal Limit 130
Thermal Limit Hysteresis 20
°C
°C
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RT9701
Typical Operating Charateristics
40
VIN = 5V
35
30
25
20
15
10
Quiessent Current ( µ A)
5
0
-40 -20 0 20 40 60 80 100 120
Temperature (ºC)
On-Resistance vs. Tem p.
160
Supply Current vs. Temp.
140
120
100
80
RT9701CX
RT9701CBL
VIN = 5V
RT9701CB
Supply Current vs. Voltage
40
Ta = 25
35
30
25
20
15
10
Quiescent Current (µ A)
5
0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Voltage (V)
On-Resistance vs. Voltage
160
140
120
100
80
Ta = 25
RT9701CBL
C
°
C
°
60
40
On-Resistance (m Ohm)
20
0
-40 -20 0 20 40 60 80 100 120
Temperature (
C)
°
Current Limit vs. Temp.
1.80
1.60
1.40
1.20
1.00
0.80
0.60
Current Limit (A)
0.40
0.20
0.00
-40 -20 0 20 40 60 80 100 120
Temperature (
C)
°
VIN = 5V
60
40
On-Resistance (mOhm)
20
0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Voltage (V)
Current Limit vs. Voltage
1.80
1.58
1.35
1.13
0.90
0.68
Current Limit (A)
0.45
0.23
0.00
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Voltage (V)
Ta = 25
C
°
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RT9701
)
g
g
µ
µ
Short Circuit Current vs. Temp.
880
795
710
625
540
455
370
Short Circuit Current (mA)
285
200
-40-20 0 20 406080100120
Temperature ( C)
°
V
IN
CE Threshold vs. Temp.
1.6
1.4
1.2
1.0
0.8
0.6
CE Threshold (V)
0.4
0.2
0.0
-40 -20 0 20 40 60 80 100 120
Temperature (ºC)
VIN = 5V
= 5V
Rising
Falling
Short Circuit Current vs. Voltage
900
800
700
600
500
400
Short Circuit Current (mA)
300
200
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Voltage (V)
Ta = 25
CE Threshold vs. Voltage
1.6
1.4
1.2
1.0
0.8
0.6
CE Threshold (V)
0.4
0.2
0.0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Voltage (V
Risin
Ta = 25
C
°
Fallin
C
°
Turn On Rising Time vs. Temp.
560
490
µS)
(
420
350
280
210
140
Turn-On Rising Time
70
0
-40 -20 0 20 40 60 80 100 120
Temperature (
RL = 30
CL = 1
C)
°
Ω
F Ceramic
VIN = 5V
Turn-Off Falling Time (µ S)
Turn Off Falling Time vs. Temp.
140
VIN = 5V
120
100
80
60
40
20
RL = 30
CL = 1
0
-40 -20 0 20 40 60 80 100 120
Temperature (° C)
Ω
F Ceramic
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RT9701
>
>
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>
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>2 >
>
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>
>
>2 >
>
>3 >
>
>
Shutdown Supply Current vs. Temp.
1.6
1.4
1.2
1.0
0.8
0.6
0.4
Turn-Off Supply Current (µ A)
0.2
0.0
-40 -20 0 20 40 60 80 100 120
Temperature (ºC)
UVLO Threshold vs. Temp.
2.00
1.75
1.50
1.25
1.00
VIN = 5V
VIN = 5V
Turn-Off Leakage Current vs. Temp.
4.0
3.5
VIN = 5V
3.0
2.5
2.0
1.5
1.0
0.5
Turn-Off Leakage Current (µ A)
0.0
-40 -20 0 20 40 60 80 100 120
Temperature (ºC)
Inrush Current Response
CL = 100µF
CL = 33µF
0.75
UVLO Threshold (V)
0.50
0.25
0.00
-40 -20 0 20 40 60 80 100 120
Temperature ( C)
°
Turn-On Response
CH1
CH2
1
1
1 >1
2
2 >2
CH1: V
CH2: V
T
T
CE
OUT
: 5V/Div
: 1V/Div
100µS/Div
RL = 30 ohm, CL = 1µF
CH1
CH2
CH3
2
2 >3
3 >4
4
2 >2
3 >3
4 >4
I
1
1
1 >1
2
2 >2
CH1: V
3
3 >3
CH2: I
OUT
CL = 1µF
T
T
T
=1A/Div
100µS/Div
Turn-Off Response
T
T
T
: 5V/Div
CE
: 100mA/Div; CH3: V
OUT
50µS/Div
VIN = 5V, RL = 1 ohm
RL = 30 ohm, CL = 1µF
: 2V/Div
OUT
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RT9701
>
>
>2 >
>
>
g
>
>
>2 >
>
>
>
>
>2 >
>
>
g
>
>
>2 >
>
>
>
>
>2 >
>
>
>
>
>2 >
>
>
CH1
CH2
CH1
UVLO at Risin
UVLO at Fallin
CH1
CH2
T
1
1
1 >1
2
2 >2
1
1
1 >1
T
T
CH1: V
CH2: V
: 1V/Div
IN
:
OUT
VCE = 3V, RL = 30 ohm, CL = 1µF
500µS/Div
Short Circuit Response
T
CH1
1
1
1 >1
CH1: V
2
2 >2
CH2: V
1
1
1 >1
: 1V/Div
IN
: 1V/Div
OUT
RL = 30 ohm, CL = 1µF
10mS/Div
Thermal Shut Down Response
T
T
CH2
CH1
CH2
2
2 >2
CH1: V
CH2: I
V
OUT
1
1
1 >1
2
2 >2
CH2: I
T
: 5V/Div
CE
: 500mA/Div
OUT
VIN = 5V, CL = 1µF
250µS/Div
Ramped Load Response
= 5V
Current Limit Threshold
: 500mA/Div
OUT
VIN = 5V, CL = 1µF
1mS/Div
V
OUT
= 4.6V
CH3
Thermal Shut Down
2
CH2
2 >2
CH1: V
CH3: I
CH2: I
1
1
1 >1
CH1
2
2 >2
CH2
CH2: I
T
: 5V/Div
CE
OUT@RL
OUT
1ohm : 500mA/Div
@short : 500mA/Div
50mS/Div
Current Limit Response
T
Loading trigger
T
VIN = 5V, CL = 0.1µF
: 1A/Div
LOAD
RL = 1 ohm
5µS/Div
V
= 5V
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RT9701
Functional Description
The RT9701 is a high-side single N-channel switch
with active-high enable input.
Input and Output
VIN (input) is the power supply connection to the
circuitry and the drain of the output MOSFET. VOUT
(output) is the source of the output MOSFET. In a
typical circuit, current flows through the switch from
VIN to VOUT toward the load. Both VOUT pins must
be short on the board and connected to the load and
so do both VIN pins but connected to the power
source.
Thermal Shutdown
Thermal shutdown shuts off the output MOSFET if
the die temperature exceeds 130°C and 20°C of
hysteresis forces the switch turning off until the die
temperature drops to 110°C.
Soft Start
In order to eliminate the upstream voltage droop
caused by the large inrush current during hot-plug
events, the “soft-start” feature effectively isolates
power supplies from such highly capacitive loads.
Undervoltage Lockout
UVLO prevents the MOSFET switch from turning on
until input voltage exceeds 1.8V (typical). If input
voltage drops below 1.8V (typical), UVLO shuts off
the MOSFET switch.
Current Limiting and Short Protection
The current limit circuit is designed to protect the
system supply, the MOSFET switch and the load
from damage caused by excessive currents. The
current limit threshold is set internally to allow a
minimum of 1.1A through the MOSFET but limits the
output current to approximately 1.5A typical. When
the output is short to ground, it will limit to a constant
current 0.5A until thermal shutdown or short condition
removed.
Applications Information
RT9701 CX
V
IN
C
IN
1 µF
VIN
VOUT
GND
Fig. 1 High Side Power Switch
RT9701CB
V
IN
C
IN
1 µF
V
CE
ON
VIN
VOUT
CE
GND
OFF
Fig. 2 High Side Power Switch with Chip Enable Control
Filtering
To limit the input voltage drop during hot-plug events,
connect a 1µF ceramic capacitor from VIN to GND.
However, higher capacitor values will further reduce
the voltage drop at the input.
Connect a 33µF capacitor from VOUT to GND. This
capacitor helps to prevent inductive parasitics from
pulling VOUT negative during turn-off or EMI damage
to other components during the hot-detachment. If
RT9701 is implanted in device end application,
minimum 1uF capacitor from VOUT to GND is
recommended and higher capacitor values are also
preferred.
In choosing these capacitors, special attention must
be paid to the Effective Series Resistance, ESR, of
the capacitors to minimize the IR drop across the
capacitor’s ESR.
C
OUT
33 µF
C
V
OUT
33 µF
OUT
V
OUT
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Ferrite beads in series with all power and ground
lines are recommended to eliminate or significantly
reduce EMI. In selecting a ferrite bead, the DC
resistance of the wire used must be kept to a
minimum to reduce the voltage drop.
Reverse current preventing
The output MOSFET and driver circuitry are also
designed to allow the MOSFET source to be
externally forced to a higher voltage than the drain
(VOUT > VIN ≥ 0). To prevent reverse current from
such condition, disable the switch (RT9701CBL) or
connect VIN to a fixed voltage under 1.3V.
Layout and Thermal Dissipation
z Place the switch as close to the USB connector as
possible. Keep all traces as short as possible to
reduce the effect of undesirable parasitic
inductance.
RT9701
z Place the output capacitor and ferrite beads as
close to the USB connector as possible.
z If ferrite beads are used, use wires with minimum
resistance and large solder pads to minimize
connection resistance.
z If the package is with dual VOUT or VIN pins,
short both the same function pins to reduce the
internal turn-on resistance.
z Under normal operating conditions, the package
can dissipate the channel heat away. Wide power-
bus planes connected to VIN and VOUT and a
ground plane in contact with the device will help
dissipate additional heat.
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RT9701
Package Information
HE
A1
8° (x2)
b
D
D1
e e
b1 b
A
C
E
A
Symbols
A 1.40 1.50 1.60 0.055 0.059 0.063
A1 0.90 1.00 1.10 0.035 0.039 0.043
b 0.36 0.42 0.48 0.014 0.016 0.018
b1 0.41 0.42 0.53 0.016 0.018 0.020
C 0.38 0.40 0.43 0.014 0.015 0.017
D 4.20 4.50 4.60 0.173 0.177 0.181
D1 1.40 1.60 1.75 0.055 0.062 0.069
HE -- -- 4.25 -- -- 0.167
E 2.40 2.50 2.60 0.094 0.098 0.102
e 1.45 1.50 1.55 0.057 0.059 0.061
Dimensions In Millimeters Dimensions In Inches
Min Typ Max Min Typ Max
3-Lead SOT-89 Surface Mount
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RT9701
C
A
D
e
45
B
31
b
1
θ
H
3
θ
2
θ
A1
L
Symbols
A 1.000 1.100 1.300 0.039 0.043 0.051
A1 -- -- 0.100 -- -- 0.004
B 1.400 1.600 1.800 0.055 0.063 0.071
C 2.600 2.800 3.000 0.102 0.110 0.118
D 2.700 2.900 3.100 0.106 0.114 0.122
H 0.100 0.150 0.250 0.004 0.006 0.010
L 0.300 0.450 0.600 0.012 0.018 0.024
b 0.300 0.400 0.500 0.012 0.016 0.020
e -- 0.950 -- -- 0.037 --
θ12°
θ25°
θ3
Dimensions In Millimeters Dimensions In Inches
Min Typ Max Min Typ Max
-- --
5-Lead SOT- 25 Surface Mount Package
--
--
8°
10°
10°
-- -- --
-- -- --
-- -- --
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RT9701
RichTek Technology Corp.
6F, No. 35, Hsintai Road, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5510047 Fax: (8863)5537749
www.richtek-ic.com.tw DS9701-01 Dec. 2000
Taipei Office (Marketing)
4F-1, No. 127, Lane 235, Paochiao Road, Hsintien City
Taipei County, Taipei, R.O.C.
Tel: (8862)89191466 Fax: (8862)89191465
Email: marketing@richtek-ic.com.tw
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