EC9521
USB Power-Distribution Switches
General Description
The EC9521 power switches are designed for USB applications. The 25mΩN-channel MOSFET power switch
satisfies the voltage drop requirements of USB specification. The protection features include current-limit protection,
short-circuit protection, and over-temperature protection. The device limits the output current at current limit
threshold level. The over-temperature protection limits the junction temperature below 140℃in case of short circuit
or over load conditions. An enable input to enable or disable the device.
Features
◆25mΩ High Side MOSFET
◆Voltage Range: 3.5V to 5.5V
◆Current-Limit and Short-Circuit Protections
◆Over-Temperature Protection
◆Iset Input
◆Enable Input
◆Lead Free and Green Devices Available
Applications
◆Notebook and Desktop Computers
◆USB Ports
◆High-Side Power Protection Switches
Pin Configurations
SOT23-5(Top View) Pin Configuration of EC9521
Ordering/Marking Information
EC9521 XX X X
R：Tape & Reel
Package Type： F：Pb Free
B2：SOT23-5 G：Green
Device | Marking | Package | Information |
EC9521B2XR | EC9521 LLLL | SOT23-5 | LLLL：Lot No |
Pin Function Description
Pin Number | Pin Name | Description |
1 | VOUT | Output Voltage Pin. The output voltage follows the input voltage. When ENB is high or EN is low, the output voltage is discharged by an internal resistor. |
2 | GND | Ground. |
3 | ISET | i set pin. ILim=120k*1.14V/Riset |
4 | EN | Enable Input. Pulling this pin to high will enable the device and pulling this pin to low will disable device. The EN pin cannot be left floating. |
5
| VIN | Power Supply Input. Connect this pin to external DC supply. |
Functional Block Diagram
Absolute Maximum Ratings
Symbol | Parameter | Rating | Unit |
VIN | VIN Input Voltage (VIN to GND) | ‐0.3 to 7 | V |
VOUT | VOUT to GND Voltage | ‐0.3 to 7 | V |
VEN | EN to GND Voltage | ‐0.3 to 7 | V |
VISET | ISET to GND Voltage | ‐0.3 to 7 | V |
TJ | Maximum Junction Temperature | 150 | oC |
TSTG | Storage Temperature Range | ‐65 to +150 | oC |
TSDR | Maximum Soldering Temperature Range, 10 seconds | 260 | oC |
Note 1:
Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Recommended Operating Conditions
Symbol | Parameter | Rating | Unit |
VIN | VIN Input Voltage (VIN to GND) | 3.5 to 5.5 | V |
IOUT | Output current | 0 to 3 | A |
TA | Ambient Temperature | ‐40 to 85 | oC |
TJ | Junction Temperature | ‐40 to +125 | oC |
θJA | Junction‐to‐Ambient Resistance in Free Air | 235 | oC/W |
Typical Application Circuit
Electrical Characteristics
Unless otherwise specified, these specifications apply over VIN=5V, VEN =5V and TA= ‐40 ~ 85 ℃. Typical values are at TA=25℃
Symbol | Parameter | Test Conditions | Min. | Typ. | Max. | Unit | ||
SUPPLY CURRENT | ||||||||
| VIN Supply Current | No load, VEN=0V | ‐ | ‐ | 1 | μA | ||
No load, VEN=5V | ‐ | 120 | 150 | μA | ||||
| Leakage Current | VOUT=GND, VEN=0V | ‐ | ‐ | 1 | μA | ||
| Reverse Leakage Current | VIN=GND, VOUT=5V, VEN=0V | ‐ | ‐ | 1 | μA | ||
POWER SWITCH | ||||||||
RDS(ON) | Power Switch On Resistance | IOUT=1A, TA= 25℃ | ‐ | 25 | 36 | mΩ | ||
UNDER‐VOLTAGE LOCKOUT (UVLO) | ||||||||
| VIN UVLO Threshold Voltage | VIN rising, TA= ‐40 ~ 85 ℃ | ‐ | 3.5 | ‐ | V | ||
| VIN UVLO Hysteresis |
| ‐ | 0.2 | ‐ | V | ||
CURRENT‐LIMIT AND SHORT‐CIRCUIT PROTECTIONS | ||||||||
ILIM | Current Limit Threshold | iset | 1.1 | ‐ | 3.9 | A | ||
Iset(Riset=51k) | 2.4 | 2.6 | 2.9 | A | ||||
ISHORT | Short-Circuit Output Current |
| 80% | ‐ | 95% | ‐ | ||
EN INPUT PIN | ||||||||
VIH | Input Logic High | VIN=3.6V to 5V | 2 | ‐ | ‐ | V | ||
VL | Input Logic Low | VIN=3.6V to 5V | ‐ | ‐ | 0.8 | V | ||
| Input Current |
| ‐ | ‐ | 1 | μA | ||
| VOUT Discharge Resistance | VEN=0V, VOUT=1V | ‐ | 40 | ‐ | Ω | ||
tD(ON) | Turn On Delay Time |
| ‐ | 30 | ‐ | μS | ||
tD(OFF) | Turn Off Delay Time |
| ‐ | 30 | ‐ | μS | ||
tSS | Soft‐Start Time | No load, COUT=1μF, VIN=5V | ‐ | 400 | ‐ | μS | ||
OVER‐TEMPERATURE PROTECTION (OTP) | ||||||||
TOTP | Over-Temperature Threshold | TJ rising | ‐ | 140 | ‐ | ℃ | ||
| Over-Temperature Hysteresis |
| ‐ | 20 | ‐ | ℃ | ||
Typical Operating Characteristics
Typical Operating Characteristics(Cont.)
Function Description
VIN Under-Voltage Lockout (UVLO)
The EC9521power switches have a built-in under-voltage lockout circuit to keep the output shutting off until internal circuitry is
operating properly. The UVLO circuit has hysteresis and a de-glitch feature so that it will typically ignore undershoot transients
on the input. When input voltage exceeds the UVLO threshold, the output voltage starts a soft-start to reduce the inrush current.
Power Switch
The power switch is an N-channel MOSFET with a low RDS (ON). The internal power MOSFET does not have the body diode.
When IC is off, the MOSFET prevents a current flowing from the VOUT back to VIN and VIN to VOUT.
Current-Limit Protection
The EC9521power switches provide the current- limit protection function. During current-limit, the devices limit output current
at current limit threshold. For reliable operation, the device should not be operated in current-limit for extended period.
Short-Circuit Protection
When the output voltage drops below 1.5V, which is caused by an over-load or a short-circuit, the devices limit the output
current down to a safe level. The short-circuit current limit is used to reduce the power dissipation during short-circuit
conditions. If the junction temperature reaches over-temperature threshold, the device will enter the thermal shutdown.
ISET
ISET pin can set the current limit by Riset: ILim =120k*1.14V/Riset
Enable/Disable
Pull the EN below 0.8V will disable the device, and pull EN above 2V will enable the device. When the IC is disabled, the
supply current is reduced to less than 1μA. The enable input is compatible with both TTL and CMOS logic levels. The EN pin
cannot be left floating.
Over-Temperature Protection
When the junction temperature exceeds 140℃, the internal thermal sense circuit turns off the power FET and allows
the device to cool down. When the device’s junction temperature cools by 20℃, the internal thermal sense circuit will
enable the device, resulting in a pulsed output during continuous thermal protection. Thermal protection is designed to
protect the IC in the event of over temperature conditions. For normal operation, the junction temperature cannot exceed
TJ=+125℃.
Application Information
Input Capacitor
A 1μF ceramic bypass capacitor from VIN to GND, located near the EC9521, is strongly recommended to suppress
the ringing during short circuit fault event. Without the bypass capacitor, the output short may cause sufficient ringing on the
input (from supply lead inductance) to damage internal control circuitry.
Output Capacitor
A low-ESR 10μF aluminum electrolytic or tantalum between VOUT and GND is strongly recommended to reduce the voltage
drop during hot-attachment of downstream peripheral. (Per USB 2.0, output ports must have a minimum 120μF of low-ESR
bulk capacitance per hub). Higher-value output capacitor is better when the output load is heavy. Additionally, bypassing the
output with a 0.1μF ceramic capacitor improves the immunity of the device to short-circuit transients.
Layout Consideration
The PCB layout should be carefully performed to maximize thermal dissipation and to minimize voltage drop, droop and EMI.
The following guidelines must be considered:
1. Please place the input capacitors near the VIN pin as close as possible.
2. Output decoupling capacitors for load must be placed near the load as close as possible for decoupling high frequency
ripples.
3. Locate EC9521and output capacitors near the load to reduce parasitic resistance and inductance for excellent load transient
performance.
4. The negative pins of the input and output capacitors and the GND pin must be connected to the ground plane of the load.
5. Keep VIN and VOUT traces as wide and short as possible.
Package Information
SOT23-5
Symbol | SOT23-5 | |||
MILLMETER | INCHES | |||
MIN. | MAX. | MIN. | MAX. | |
A |
| 1.45 |
| 0.057 |
A1 | 0.00 | 0.15 | 0.000 | 0.006 |
A2 | 0.90 | 1.30 | 0.035 | 0.051 |
b | 0.30 | 0.50 | 0.012 | 0.020 |
c | 0.08 | 0.22 | 0.003 | 0.009 |
D | 2.70 | 3.10 | 0.106 | 0.122 |
E | 2.60 | 3.00 | 0.102 | 0.118 |
E1 | 1.40 | 1.80 | 0.055 | 0.071 |
e | 0.95BSC | 0.037BSC | ||
e1 | 1.90BSC | 0.075BSC | ||
L | 0.30 | 0.60 | 0.012 | 0.024 |
θ | 0° | 8° | 0° | 8° |
