Page 1
MIC2525 Micrel
MIC2525
USB Power Control Switch
Not Recommended for New Designs
Refer to MIC2025
General Description
The MIC2525 is an integrated high-side power switch, optimized for self-powered and bus-powered Universal Serial
Bus (USB) applications. Few external components are necessary to satisfy USB requirements.
The MIC2525 satisfies the following USB requirements: each
switch channel supplies up to 500mA as required by USB
downstream devices; the switch’s low on-resistance meets
USB voltage drop requirements; fault current is limited to
typically 750mA, well below the UL 25VA safety requirements; and a flag output is available to indicate fault conditions to the local USB controller. Soft start eliminates the
momentary voltage drop on the upstream port that may occur
when the switch is enabled in bus-powered applications.
Additional features include thermal shutdown to prevent
catastrophic switch failure from high-current loads,
undervoltage lockout (UVLO) to ensure that the device remains off unless there is a valid input voltage present, and
3.3V and 5V logic compatible enable inputs.
The MIC2525 is a UL recognized component and is available
in active-high and active-low versions in 8-pin DIP and SOIC
packages.
For new designs, please see the MIC2025/2075.
Features
• Compliant to USB specifications
• UL Recognized Component
• 3V to 5.5V input
• 500mA minimum continuous load current per port
• 140mΩ maximum on-resistance
• 1.25A maximum short circuit current limit
• Open-drain fault flag pins
• 110µA typical on-state supply current
• 1µA typical off-state supply current
• Output can be forced higher than input (off-state)
• Thermal shutdown
• 2.4V typical undervoltage lockout (UVLO)
• 1ms turn-on (soft-start) and fast turnoff
• Active-high or active-low enable versions
• 8-pin SOIC and DIP packages
Applications
• USB hosts and self-powered hubs
• USB bus-powered hubs
• Hot plug-in power supplies
• Battery-charger circuits
Typical Application
4.50V to 5.25V
Upstream V
100mA max.
BUS
V
BUS
D+
D–
GND
Data
1µF
MIC5207-3.3
IN OUT
GND
3.3V
VIN
1µF
10k
ON/OFF
OVERCURRENT
GND
100k
MIC2525-23.3V USB Controller
EN OUT
FLG IN
GND OUT
NC
Single-Port USB Self-Powered Hub
NC
V
CC
5.0V
0.1µF
150µF
Ferrite
Beads
Data
V
BUS
D+
D–
GND
USB
Port
UL Recognized Component
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
January 2000 1 MIC2525
Page 2
MIC2525 Micrel
Ordering Information
Part Number Enable Temperature Range Package
MIC2525-1BM Active High –40°C to +85°C 8-Pin SOIC
MIC2525-2BM Active Low –40°C to +85°C 8-Pin SOIC
MIC2525-1BN Active High –40°C to +85°C 8-pin DIP
MIC2525-2BN Active Low –40°C to +85°C 8-pin DIP
Pin Configuration
MIC2525
EN
1
OUT
8
FLG
GND
NC
(EN) 1
(FLG) 2
Pin Description
Pin Number Pin Name Pin Function
1 EN Enable (Input): Logic-compatible enable input. High input > 2.1V typical.
2 FLG Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent,
3 GND Ground: Supply return.
4, 5 NC Not internally connected. (For pin compatibility with the MIC2505, connect
7 IN Supply Input: Output MOSFET drain. Also supplies IC’s internal circuitry.
6, 8 OUT Switch Output: Output MOSFET source. Typically connect to switched side
2
3
4
IN
7
OUT
6
NC
5
8-Pin SOIC (M)
8-Pin DIP (N)
MIC2525
LOGIC,
CHARGE
PUMP
3 (GND)
Low input <1.9V typical (-1 active high, -2 active low).
UVLO and thermal shutdown.
pin 7 to pin 5 and leave pin 4 unconnected.)
Connect to positive supply.
of load.
6, 8 (OUT)
7 (IN)
MIC2525 2 January 2000
Page 3
MIC2525 Micrel
Absolute Maximum Ratings (Note 1)
Supply Voltage (V
Fault Flag Voltage (V
Fault Flag Current (I
Output Voltage (V
Output Current (I
Control Input (V
) .....................................................+6V
IN
)..............................................+6V
FLG
) ............................................50mA
FLG
) ..................................................+6V
OUT
)...............................Internally Limited
OUT
)......................................... –0.3V to 12V
EN
Operating Ratings (Note 2)
Supply Voltage (V
Ambient Operating Temperature (T
Thermal Resistance
SOIC (θ
).........................................................120°C/W
JA
DIP(θJA).............................................................130°C/W
) ...................................... +3V to +5.5V
IN
) ........ –40°C to +85°C
A
Storage Temperature (TS) ....................... –65°C to +150°C
Lead Temperature (Soldering 5 sec.) ....................... 260°C
ESD Rating, Note 3 ......................................................2kV
Electrical Characteristics
VIN = +5V; TA = 25°C; unless noted.
Parameter Condition Min Typ Max Units
Supply Current Note 4, switch off, OUT = open 0.75 5 µA
Note 4, switch on, OUT = open 110 160 µA
Enable Input Threshold low-to-high transition 2.1 2.4 V
high-to-low transition, Note 4 0.8 1.9 V
Enable Input Current VEN = 0V to 5.5V –1 ±0.01 1 µA
Enable Input Capacitance 1pF
Switch Resistance VIN = 5V, I
VIN = 3.3V, I
Output Turn-On Delay RL = 10Ω each output 0.5 ms
Output Turn-On Rise Time RL = 10Ω each output 1 ms
Output Turnoff Delay RL = 10Ω each output 1 20 µs
Output Turnoff Fall Time RL = 10Ω each output 1 20 µs
Output Leakage Current output disabled 10 µA
Continuous Load Current 0.5 A
Short-Circuit Current Limit enable into load, V
Current-Limit Threshold ramped load applied to enabled output, V
Overtemperature Shutdown TJ increasing 135 °C
Threshold
Error Flag Output Resistance VIN = 5V, IL = 10mA 10 25 Ω
Error Flag Off Current V
UVLO Threshold VIN = increasing 2.5 V
TJ decreasing 125 °C
VIN = 3.3V, IL = 10mA 15 40 Ω
= 5V 0.01 1 µA
FLAG
VIN = decreasing 2.3 V
= 500mA 100 140 mΩ
OUT
= 500mA 140 180 mΩ
OUT
= 4.0V 0.5 0.75 1.25 A
OUT
≤ 4.0V, Note 5 1.6 2.2 A
OUT
Note 1. Exceeding the absolute maximum rating may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Note 4. Off is ≤ 0.8V and on is ≥ 2.4V for the MIC2525-1. Off is ≥ 2.4V and on is ≤ 0.8V for the MIC2525-2. The enable input has approximately
Note 5. See “Functional Characteristics: Current-Limit Response” photo.
200mV of hysteresis. See control threshold charts.
January 2000 3 MIC2525
Page 4
MIC2525 Micrel
Typical Characteristics
VIN = 5V; TA = 25°C; one switch section; unless noted.
Output On-Resistance
vs. Supply Voltage
110
100
90
OUTPUT RESISTANCE (mΩ)
80
3.0 3.5 4.0 4.5 5 5.5
Awaiting Full
Characterization
Data
RL = 44Ω
T = 25°C
SUPPLY VOLTAGE (V)
On-State Supply Current
vs. Supply Voltage
250
200
150
100
50
SUPPLY CURRENT (µA)
0
0246
SWITCH ON
SUPPLY VOLTAGE (V)
Output On-Resistance
140
120
100
ON-RESISTANCE (mΩ)
vs. Temperature
80
60
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
RL = 44Ω
VIN = 5V
Off-State Supply Current
vs. Supply Voltage
2.0
1.5
1.0
0.5
SUPPLY CURRENT (µA)
0
SWITCH OFF
23456
SUPPLY VOLTAGE (V)
UVLO Threshold Voltage
3.0
2.5
2.0
THRESHOLD VOLTAGE (V)
1.5
vs. Temperature
VIN RISING
VIN FALLING
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Control Threshold
vs. Supply Voltage
2.5
2.0
1.5
THRESHOLD VOLTAGE (V)
1.0
2345
V
RISING
CTL
V
FALLING
CTL
SUPPLY VOLTAGE (V)
On-State Supply Current
200
150
100
SUPPLY CURRENT (µA)
vs. Temperature
50
SWITCH ON
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Output Rise Time
vs. Temperature
5
4
3
2
TIME (µs)
1
0
-40 -20 0 20 40 60 80 100
Awaiting Full
Characterization
Data
TEMPERATURE (°C)
Off-State Supply Current
2.0
1.5
1.0
0.5
SUPPLY CURRENT (µA)
vs. Temperature
SWITCH OFF
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Output Fall Time
1.0
0.8
0.6
0.4
TIME (ms)
0.2
vs. Temperature
Awaiting Full
Characterization
Data
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Control Threshold
2.5
2.0
1.5
ENABLE VOLTAGE (V)
1.0
vs. Temperature
VEN RISING
VEN FALLING
VIN = 5V
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Current-Limit Threshold
2.0
1.8
1.6
1.4
CURRENT (A)
1.2
1.0
vs. Temperature
CURRENT LIMIT
THRESHOLD
SHORT CIRCUIT
CURRENT LIMIT
-25 0 25 50 75 100
TEMPERATURE (°C)
MIC2525 4 January 2000
Page 5
MIC2525 Micrel
Functional Characteristics
V
V
V
I
V
V
IN
OUT
FLG
OUT
EN
FLG
Input V oltage
Response
EN
V
(5V/div.)
2.6V (UVLO) Threshold
(2V/div.)
V
V
FLG
(5V/div.)
OUT
(2V/div.)
T urn-On, T urnoff
Characteristics
(2V/div.)
VEN = V
(5V/div.)
(200mA/div.)
TIME (100ns/div.)
T urn-On, T urnoff
Characteristics
(5V/div.)
RL = 35Ω
= 15µF
C
L
IN
OUT
I
(100mA/div.)
TIME (2.5ms/div.)
Short Circuit Response
(Short Applied to Output)
FLG
V
(5V/div.)
144mA
RL = 35Ω
CL = 10µF
(5V/div.)
V
I
OUT
OUT
OUT
V
I
OUT
(2V/div.)
1A Short Circuit Current Limit
(1A/div.)
Thermal Shutdown
TIME (500ms/div.)
(2V/div.)
144mA
RL = 35Ω
= 150µF
C
L
(100mA/div.)
TIME (2.5ms/div.)
Short Circuit Response
Enable into Short Circuit
EN
V
(5V/div.)
FLG
V
(5V/div.)
OUT
V
I
OUT
(2V/div.)
1.1A Short Circuit
(1A/div.)
Current-Limiting
TIME (250ms/div.)
Thermal
Shutdown
January 2000 5 MIC2525
Page 6
MIC2525 Micrel
OUT
V
(5V/div.)
FLG
V
(5V/div.)
OUT
I
(1A/div.)
Test Circuit
Short Circuit Transient Response
(Short Applied to Output)
2.76A
1A Current Limit
TIME (500µs/div.)
5V
10k
0.1µF
MIC2525
EN OUT
FLG IN
GND OUT
NC NC
Current-Limit Response
(Ramped Load)
FLG
V
(5V/div.)
OUT
V
(2V/div.)
Current Limit
Threshold
OUT
I
(1A/div.)
TIME (1ms/div.)
Ferrite
Bead
I
OUT
I
C
L
R
L
LOAD
(for Current
Limit Response)
1A Current
Limit
Functional Characteristics Test Circuit
MIC2525 6 January 2000
Page 7
MIC2525 Micrel
Block Diagram
EN
OSC.
CHARGE
PUMP
THERMAL
SHUTDOWN
UVLO
GND
REFERENCE
GATE
CONTROL
1.2V
CURRENT
LIMIT
IN
OUT
FLG
January 2000 7 MIC2525
Page 8
MIC2525 Micrel
Functional Description
The MIC2525-1 and MIC2525-2 are high-side switches with
active-high and active-low enable inputs, respectively. Fault
conditions turn off or inhibit turn-on of the output transistor,
depending upon the type of fault, and activate the open-drain
error flag transistor making it sink current to ground.
Input and Output
IN (input) is the power supply connection to the logic circuitry
and the drain of the output MOSFET. OUT (output) is the
source of the output MOSFET. In a typical circuit, current
flows through the switch from IN to OUT toward the load. If
V
is greater than VIN when the switch is enabled, current
OUT
will flow from OUT to IN since the MOSFET is bidirectional
when on.
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 (V
this situation, the MIC2525 avoids undesirable current flow
from OUT to IN. If VIN < 2.5V, UVLO disables the switch.
Thermal Shutdown
Thermal shutdown shuts off the output MOSFET and signals
the fault flag if the die temperature exceeds 135°C. 10°C of
hysteresis prevents the switch from turning on until the die
temperature drops to 125°C. Overtemperature detection
functions only when the switch is enabled.
Current Limit Induced Thermal Shutdown
Internal circuitry increases the output MOSFET on-resistance until the series combination of the MOSFET on-resistance and the load impedance limit current to typically 750mA.
The increase in power dissipation, in most cases, will cause
the MIC2525 to go into thermal shutdown. When this is
undesirable, thermal shutdown can be avoided by externally
responding to the fault and disabling the current limited
channel before the shutdown temperature is reached. The
delay between the flag indication of a current limit fault and
thermal shutdown will vary with ambient temperature, board
layout, and load impedance, but is typically several hundred
milliseconds. The USB controller must therefore recognize a
fault and disable the switch within this time. If the fault is not
removed or the switch is not disabled within this time, then the
device will enter into a thermal oscillation of about 2Hz. This
does not cause any damage to the device. Refer to “Func-
tional Characteristics: Thermal Shutdown Response.”
> VIN) when the output is off. In
OUT
Undervoltage Lockout
UVLO (undervoltage lockout) prevents the output MOSFET
from turning on until VIN exceeds approximately 2.5V. In the
undervoltage state, the FLAG will be low. After the switch
turns on, if the voltage drops below approximately 2.3V,
UVLO shuts off the output MOSFET and signals fault flag.
Undervoltage detection functions only when the switch is
enabled.
Current Sensing and Limiting
The current-limit threshold is preset internally. The preset
level prevents damage to the output MOSFET and external
load but allows a minimum current of 0.5A through the output
MOSFET.
The current-limit circuit senses a portion of the output FET
switch current. The current sense resistor shown in the block
diagram is virtual and has no voltage drop. The reaction to an
overcurrent condition varies with three scenarios:
Switch Enabled into Short Circuit
If a switch is powered on or enabled into a heavy load or shortcircuit, the switch immediately goes into a constant-current
mode, reducing the output voltage. The fault flag goes low
until the load is reduced. See the “Functional Characteristics:
Short Circuit Response, Enabled into Short Circuit” photo.
Short Circuit Applied to Output
When a heavy load is applied, a large transient current may
flow until the current limit circuitry responds. Once this
occurs, the device limits current to less than the short-circuit
current limit specification. See the “Short Circuit Transient
Response, Short Applied to Output” graph.
Current-Limit Response
The MIC2525 current-limit profile exhibits a small foldback
effect of approximately 500mA. Once this current-limit threshold is exceeded the device enters constant-current mode.
This constant current is specified as the short circuit current
limit in the “Electrical Characteristics” table. It is important to
note that the MIC2525 will deliver load current up to the
current-limit threshold which is typically 1.6A. Refer to “Func-
tional Characteristics: Current-Limit Response” photo for
details.
Fault Flag
FLG is an N-channel, open-drain MOSFET output. The faultflag is active (low) for one or more of the following conditions:
undervoltage (while 2V < VIN < 2.7), current limit, or thermal
shutdown. The flag output MOSFET is capable of sinking a
10mA load to typically 100mV above ground.
MIC2525 8 January 2000
Page 9
MIC2525 Micrel
Applications Information
Supply Filtering
A 0.1µF to 1µF bypass capacitor from IN to GND, located at
the device, is strongly recommended to control supply transients. Without a bypass capacitor, an output short may
cause sufficient ringing on the input (from supply lead inductance) to damage internal control circuitry.
Input or output transients must not exceed the absolute
maximum supply voltage (V
duration.
MIC2525
18
EN OUT
27
FLG
36
GND OUT
45
NC NC
IN
Figure 1. Supply Bypassing
= 6V) even for a short
IN max
3V to 5.5V
0.1µF to 1µF
Enable Input
EN must be driven logic high or logic low for a clearly defined
input. Floating the input may cause unpredictable operation.
EN should not be allowed to go negative with respect to GND.
Soft Start
The MIC2525 presents a high impedance when off, and
slowly becomes a low impedance as it turns on. This reduces
inrush current and related voltage drop that results from
charging a capacitive load, satisfying the USB voltage droop
requirements for bus-powered applications as shown in
Figure 2.
The soft start circuit shown in Figure 3 can be utilized to meet
USB transient regulation specifications with large load capacitances (C
> 10uF). The MIC2525 will provide inrush
BULK
current limiting for these applications.
Transient Overcurrent Filter
When the MIC2525 is enabled, large values of capacitance
at the output of the device will cause inrush current to exceed
the short circuit current-limit threshold of the device and
assert the flag. The duration of this time will depend on the
size of the output capacitance. Refer to the “Functional
Characteristics” turn-on and turnoff behaviors for details.
V
BUS
USB Host
GND
Cable
V
BUS
USB Hub
MIC2525-xBM
18
EN OUT
27
FLG
36
GND OUT
4.7
4
µF
NC
Bus Powered Hub
NC
IN
5
0.1µF
Figure 2. Soft-Start Application
4.7
µF
USB
Controller
C
BULK
C
BULK
Controller
Function
MIC2525-2
18
EN OUT
27
FLG
36
GND OUT
4
NC
IN
NC
5
Downstream USB DeviceCable
USB
USB
Capacitive
Load
GND
Cable
USB Peripheral
Figure 3. Inrush Current-Limit Application
January 2000 9 MIC2525
Page 10
MIC2525 Micrel
During the capacitance charging time, the device enters into
constant-current mode. As the capacitance is charged, the
current decreases below the short circuit current-limit threshold, and the flag will then be deasserted.
In USB applications, it is required that output bulk capacitance is utilized to support hot-plug events. When the MIC2525
is enabled, the flag may go active for about 1ms due to inrush
current exceeding the current-limit setpoint. Additionally,
during hot-plug events, inrush currents may also cause the
flag to go active for 30µs. Since these conditions are not valid
overcurrent faults, the USB controller must ignore the flag
during these events. To prevent this erroneous overcurrent
reporting, a 1ms RC filter as shown in Figure 4 may be used.
Alternatively, a 1ms debounce routine may be programmed
into the USB logic controller, eliminating the need for the RC
filter.
V+
USB Controller
OVERCURRENT
0.1
µF
10k
10k
MIC2525
18
EN OUT
27
FLG
36
GND OUT
45
NC NC
IN
Figure 4. Transient Filter
MIC2525 10 January 2000
Page 11
MIC2525 Micrel
Package Information
0.026 (0.65)
MAX)
PIN 1
0.157 (3.99)
0.150 (3.81)
0.050 (1.27)
0.064 (1.63)
0.045 (1.14)
TYP
0.197 (5.0)
0.189 (4.8)
0.380 (9.65)
0.370 (9.40)
DIMENSIONS:
INCHES (MM)
0.020 (0.51)
0.013 (0.33)
0.0098 (0.249)
0.0040 (0.102)
0°–8°
SEATING
PLANE
8-Pin SOP (M)
PIN 1
0.135 (3.43)
0.125 (3.18)
0.050 (1.27)
0.016 (0.40)
0.244 (6.20)
0.228 (5.79)
DIMENSIONS:
INCH (MM)
45°
0.010 (0.25)
0.007 (0.18)
0.255 (6.48)
0.245 (6.22)
0.300 (7.62)
0.018 (0.57)
0.100 (2.54)
0.130 (3.30)
0.0375 (0.952)
0.380 (9.65)
0.320 (8.13)
8-Pin Plastic DIP (N)
0.013 (0.330)
0.010 (0.254)
January 2000 11 MIC2525
Page 12
MIC2525 Micrel
MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
© 2000 Micrel Incorporated
MIC2525 12 January 2000
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