RY2121
1CH ADJ Current-Limited Power Distribution Switch
Features
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Single-Channel Power Distribution Switch
Programmable Current Limit in 0.4A~2A Output
Current
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Enable polarity: Active High
2.4V to 5.5V Supply Range
Under-Voltage Lockout
-40°C to +85°C Ambient Temperature Range
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•
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Accurate Current Limit
15μA Quiescent Current
80mΩ MOSFET
Thermal-Shutdown Protection
Built-In Soft Start
Reverse Current Blocking (No Body Diode)
Available in SOT23-5 Package
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ONT Boxes
USB Ports and Hubs, Laptops, and Desktops
Smartphone and PDA
MiniPCI Accessories
Applications
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Set-Top Boxes
Wi-Fi Router/AP
USB 3G Datacard/ USB Dongle
High-Definition Digital TVs
General Description
The RY2121 Power Distribution Switch features internal current limiting to prevent damage to host devices due to
faulty load conditions. The RY2121 develops ultra-low on-resistance switch with programmable current limiting to
protect the power source from over current and short circuit conditions. It integrates the over temperature protection
and discharges the output capacitor during the shutdown. In case the output is pulled higher than the input voltage
under the shutdown, the RY2121 can block the current flowing from the output to the input. The RY2121 is available
in SOT23-5 package.
Typical Application Circuit
VIN
CIN
IN
ON/
OFF
VOUT
OUT
EN
SET
GND
COUT
RSET
Basic Application Circuit
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RY2121
1CH ADJ Current-Limited Power Distribution Switch
Pin Description
Pin Configuration
TOP VIEW
OUT
1
GND
2
SET
3
5
IN
4
EN
SOT23-5
Top Marking: MEYLL (device code: ME, Y=year code, LL= lot number code)
Pin Description
Pin
Name
Function
1
OUT
Output Pin.
2
GND
Ground Pin.
3
SET
Current limit programming Pin. Connect a resistor RSET from this pin to GND to
program the current limit.
4
EN
ON/OFF control. Pull high to enable IC, Do not float.
5
IN
Power Supply Pin
Order Information
Marking
Part No.
Model
Description
Package
T/R Qty
MEYLL
70702013
RY2121
RY2121 1CH Current Limited IC, VIN 2.4VSOT23-5
5.5V, ILIM ADJ, Active High, SOT23-5
3000PCS
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RY2121
1CH ADJ Current-Limited Power Distribution Switch
Absolute Maximum Ratings (1) (2) (3)
All Pins Voltage ……………...……………………...………….…………………..……..………...… -0.3V to +6V
Operating Virtual Junction (TJ) ……………...………......……………….……..……..………..… -40°C to +150°C
Ambient Temperature Operating Range (TA) …………………..…………………………………... -40°C to +85°C
Storage Temperature Range (TS) …………………………………...……………………………... -55°C to +150°C
Lead Temperature (Soldering, 10s) (TL) ………………………..…………………………………………... +260°C
Junction-to-ambient thermal resistance (RθJA) …………………...…………..…………..…………….…. 200°C/W
Junction-to-case thermal resistance (RθJC) ……………..……….………………………...…………….… 130°C/W
Note 1: Exceeding these ratings may damage the device.
Note 2: The device is not guaranteed to function outside of its operating conditions.
Note 3: 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. Pin 2 of SOT23-5 packages is the case position for θJC
measurement.
Recommended Operating Conditions
Input Voltage Pin …….………....…………..……………………….……………..……..……....… +2.4V to +5.5V
All Other Pins …………...…….…...…………..……….……………………..………..........……....… 0V to +5.5V
Junction Temperature Range (Tj) …………..………………………………………………….….. -40°C to +125°C
Ambient Temperature Range (TA) ………...………………..………………………..……………... -40°C to +85°C
Electrical Characteristics(4)
(VIN = 5V, CL=1μF, per channel, TA = 25°C unless otherwise specified)
Parameter
Symbol
Input Voltage Range
VIN
Shutdown Input Current
ISHDN
Open load, IC Disabled
0.6
Quiescent Supply Current
IQ
Open load, IC Enabled
20
μA
FET RON
RDS(ON)1
80
mΩ
ENB Rising Threshold
VENB(H)
ENB Falling Threshold
VENB(L)
ENB Leakage
IENB
IN UVLO Threshold
VIN,UVLO
IN UVLO Hysteresis
VIN,HYS
ILIM
Over Current Limit
Turn-ON Time
(5)
Turn-OFF Time
(5)
Test Conditions
Min
Typ.
2.4
Max
Unit
5.5
V
1
μA
1.2
V
VENB=5.5V
0.8
V
1
μA
2.3
V
0.1
RSET=6.8kΩ
0.75
1.0
V
1.25
A
ILIM(MIN)
0.4
A
ILIM(MAX)
2
A
TON
RL=10Ω, CL=1uF
120
μS
TOFF
RL=10Ω, CL=1μF
10
μS
OUT Shutdown Discharge Resistance
RDIS
150
Ω
Thermal Shutdown Temperature
TSD
130
℃
Thermal Shutdown Hysteresis
THYS
20
℃
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RY2121
1CH ADJ Current-Limited Power Distribution Switch
Note 4: The device is not guaranteed to function outside its operating conditions.
Note 5: Measured from (50%) EN signal to (90%) output signal.
Typical Performance Characteristics (6) (7)
Note 6: Performance waveforms are tested on the evaluation board.
Note 7: VIN = 5V, COUT = 1µF, RSET = 6.8kΩ, TA = +25ºC, unless otherwise noted.
VEN
tr
90%
VoUT
10%
90%
50%
50%
tf
ton
10%
toff
90%
VoUT
10%
Figure 1 Tr, Tf, Ton, Toff waveforms
Turn on Delay vs. Input Voltage
Turn off Delay vs. Input Voltage
Supply Current, Output Enabled vs.
Input Voltage
VEN=5V,RLOAD=5Ω
VEN=5V,RLOAD=5Ω
Supply Current, Output Disabled vs.
Static Drain-Source On-State
Input to Output Voltage vs.
Input Voltage
Resistance vs. Input Voltage
Load Current
VEN = 0V
VEN = 5V,ILOAD=0.5A
VEN = 5V
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VEN = 5V
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RY2121
1CH ADJ Current-Limited Power Distribution Switch
Current Limit vs. Input Voltage
Threshold Trip Current vs.
Current Limit vs. RSET
Input Voltage
Turn on Delay Rise Time
Turn off Delay Fall Time
Threshold Trip Current with Ramped Load
Enabled Device
VEN = 5V,RLOAD=5Ω
1Ω Load Connected to Enabled Device
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Short Circuit Current,Device Enabled
Current Limit vs. RSET
into Short
ILIM=0.4~1.5A
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RY2121
1CH ADJ Current-Limited Power Distribution Switch
Function Block Diagram
UVLO
REVERSE CURRENT BLOCKING
CURRENT
SENSE
LOGIC
AMPLIFER
IN
EN
OUT
-
SET
+
+
VREF
-
THERMAL SENSE
GND
Figure 2 Function Block Diagram
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RY2121
1CH ADJ Current-Limited Power Distribution Switch
Functions Description
Current Limit
The RY2121 provides a constant current limit that can be programmed by an external resistor. Once the device
reaches its current limit threshold, the internal circuit regulates the gate voltage to hold the current in the power
MOSFET constant. Below table can be taken as a reference to choose RSET to set the current limit threshold.
RSET (kΩ)
Typical Current Limit (mA)
5.1
1500
5.6
1420
6.8
1180
7.5
1080
8.2
980
9.1
880
10
820
11
760
12
700
13
640
15
580
16
540
18
510
20
480
30
340
43
238
51
202
68
160
82
128
100
94
150
56
180
52
200
48
Table 1 Current Limit Threshold Setting
Over Current
When the load exceeds trip current (minimum threshold current triggering constant-current mode) or short circuited,
RY2121 switches into to constant-current mode (current limit value). RY2121 will be shut down only if the
overcurrent condition stays long enough to trigger thermal protection.
Trigger overcurrent protection for different overload conditions occurring in applications:
1) The output has been shorted or overloaded before the device is enabled or input applied. RY2121 detects the
short or overload and immediately switches into a constant-current mode.
2) A short or an overload occurs after the device is enabled. The device switches into constant current mode after
the current-limit circuit has been tripped (reached the trip current threshold). However, high current may flow for a
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RY2121
1CH ADJ Current-Limited Power Distribution Switch
short period of time before the current-limit circuit can react.
3) Output current has been gradually increased beyond the recommended operating current. The load current rises
until the trip current threshold is reached or until the thermal limit of the device is exceeded. Once the trip threshold
has been reached, the device switches into its constant-current mode.
Thermal Protection
If the current limit block starts to regulate the output current, the power loss on power MOSFET will cause the IC
temperature rise. The die temperature is internally monitored until the thermal limit is reached. Once this
temperature is reached, the switch will turn off to allow the chip to cool until the over temperature fault remove.
The over temperature threshold is 130℃ and hysteresis is 20℃.
Under-voltage Lockout (UVLO)
This circuit is used to monitor the input voltage to ensure that the RY2121 is operating correctly. This UVLO circuit
also ensures that there is no operation until the input voltage reaches the minimum spec.
Reverse Current Blocking
In case the output is pulled higher than the input voltage under the shutdown, the RY2121 can block the current
flowing from the output to the input. This prevents damage to devices on the input side of the RY2121 by
preventing significant current from sinking into the input capacitance.
Output Discharge
RY2121 has output discharge function. It can discharge the output capacitor by internal pulldown resistance during
shutdown.
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RY2121
1CH ADJ Current-Limited Power Distribution Switch
Package Description
SOT23-5
2.80
3.00
0.95
BSC
0.60
TYP
1.20
TYP
EXAMPLE
TOP MARK
AAAAA
1.50
2.60
1.70
3.00
2.60
TYP
PIN 1
TOP VIEW
RECOMMENDED PAD LAYOUT
GAUGE PLANE
0.25 BSC
0.90
1.30
1.45 MAX
SEATING PLANE
0.30
0.50
0.95 BSC
FRONT VIEW
0.00
0.15
0° ~8°
0.30
0.55
0.09
0.20
SIDE VIEW
NOTE:
1. CONTROL DIMENSION IS IN INCHES. DIMENSION IN BRACKET IS IN MILLIMETERS.
2. PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
3. PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
4. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.004" INCHES MAX.
5. DRAWING CONFORMS TO JEDEC MS-012, VARIATION BA.
6. DRAWING IS NOT TO SCALE.
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