Datasheet MIC2076-1BN, MIC2076-2BM, MIC2076-2BN, MIC2076-1BM, MIC2026-2BN Datasheet (MICREL)

MIC2026/2076 Micrel

MIC2026/2076

Dual-Channel Power Distribution Switch

Preliminary Information

General Description

The MIC2026 and MIC2076 are high-side MOSFET switches
optimized for general-purpose power distribution requiring
circuit protection.

The MIC2026/76 are internally current limited and have
thermal shutdown that protects the device and load.

The MIC2076 offers “smart” thermal shutdown that reduces
current consumption in fault modes. When a thermal shut­down fault occurs, the output is latched off until the faulty load
is removed. Removing the load or toggling the enable input
will reset the device output.

Both devices employ soft-start circuitry that minimizes inrush
current in applications where highly capacitive loads are
employed.

A fault status output flag is asserted during overcurrent and
thermal shutdown conditions. Transient faults are internally
filtered.

The MIC2026/76 are available in 8-pin DIP or 8-lead SOP.

Features

• 140mΩ maximum on-resistance per channel

• 2.7V to 5.5V operating range

• 500mA minimum continuous current per channel

• Short-circuit protection with thermal shutdown

• Thermally isolated channels

• Fault status flag with 3ms filter

eliminates false assertions

• Undervoltage lockout

• Reverse current flow blocking (no “body diode”)

• Circuit breaker mode (MIC2076)

• Logic-compatible inputs

• Soft-start circuit

• Low quiescent current

Pin-compatible with MIC2526

Applications

• USB peripherals

• General purpose power switching

• ACPI power distribution

• Notebook PCs

• PDAs

• PC card hot swap

Typical Application

V

CONT.

Logic Controller

VIN

OVERCURRENT
OVERCURRENT

10k
10k

ON/OFF

ON/OFF

MIC2026-2

ENA OUTA
FLGA IN
FLGB GND
ENB OUTB

V

CC

2.7V to 5.5V

0.1µF

Load

Load

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com

March 2000 1 MIC2026/2076

MIC2026/2076 Micrel

Ordering Information

Part Number Enable Temperature Range Package

MIC2026-1BM Active High –40°C to +85°C 8-lead SOP
MIC2026-2BM Active Low –40°C to +85°C 8-lead SOP
MIC2026-1BN Active High –40°C to +85°C 8-pin DIP
MIC2026-2BN Active Low –40°C to +85°C 8-pin DIP
MIC2076-1BM Active High –40°C to +85°C 8-lead SOP
MIC2076-2BM Active Low –40°C to +85°C 8-lead SOP
MIC2076-1BN Active High –40°C to +85°C 8-pin DIP
MIC2076-2BN Active Low –40°C to +85°C 8-pin DIP

Pin Configuration

ENA
FLGA
FLGB

ENB

Pin Description

Pin Number Pin Name Pin Function

1 ENA Switch A Enable (Input): Logic-compatible enable input. Active high (-1) or

2 FLGA Fault Flag A (Output): Active-low, open-drain output. Indicates overcurrent

3 FLGB Fault Flag B (Output): Active-low, open-drain output. Low indicates

4 ENB Switch B Enable (Input): Logic-compatible enable input. Active-high (-1) or

5 OUTB Switch B (Output)
6 GND Ground
7 IN Input: Switch and logic supply input.
8 OUTA Switch A (Output)

MIC2026/76

1
2
3
4

8
7
6
5

OUTA
IN
GND
OUTB

8-Lead SOP (BM)

8-Pin DIP (BN)

active low (-2).

or thermal shutdown conditions. Overcurrent conditions must last longer
than tD in order to assert FLGA.

overcurrent or thermal shutdown conditions.Overcurrent conditions must last
longer than tD in order to assert FLGB.

active-low (-2).

MIC2026/2076 2 March 2000

MIC2026/2076 Micrel

Absolute Maximum Ratings (Note 1)

Supply Voltage (V
Fault Flag Voltage (V
Fault Flag Current (I
Output Voltage (V
Output Current (I
Enable Input (I

) ...................................... –0.3V to +6V

IN

)..............................................+6V

FLG

) ............................................25mA

FLG

) ..................................................+6V

OUT

)...............................Internally Limited

OUT

)....................................–0.3V to VIN + 3V

EN

Operating Ratings (Note 2)

Supply Voltage (V
Ambient Temperature (T
Junction Temperature Range (T
Thermal Resistance

SOP (θJA) ..........................................................160°C/W

DIP(θJA).............................................................105°C/W

) ................................... +2.7V to +5.5V

IN

).........................–40°C to +85°C

A

) ........... Internally Limited

J

Storage Temperature (TS) ...................... –65°C to +150 °C

ESD Rating, Note 3

Electrical Characteristics

VIN = +5V; TA = 25°C, bold values indicate –40°C ≤ TA ≤ +85°C; unless noted
Symbol Parameter Condition Min Typ Max Units

I

DD

V

EN

I

EN

R

DS(on)

t

ON

t

R

t

OFF

t

F

I

LIMIT

t

D

Supply Current MIC20x6-1, V

(switch off), OUT = open
MIC20x6-2, V

(switch off), OUT = open
MIC20x6-1, V

(switch on), OUT = open
MIC20x6-2, V

(switch on), OUT = open

ENA

ENA

ENA

ENA

= V

= V

= V

= V

≤ 0.8V 0.75 5 µA

ENB

≥ 2.4V 0.75 5 µA

ENB

≥ 2.4V 100 160 µA

ENB

≤ 0.8V 100 160 µA

ENB

Enable Input Threshold low-to-high transition 1.7 2.4 V

high-to-low transition 0.8 1.45 V
Enable Input Hysteresis 250 mV
Enable Input Current V

= 0V to 5.5V –1 0.01 1 µA

EN

Enable Input Capacitance 1 pF
Switch Resistance VIN = 5V, I

VIN = 3.3V, I
Output Leakage Current MIC20x6-1, V

MIC20x6-1, V

= 500mA 90 140 mΩ

OUT

= 500mA 100 160 mΩ

OUT

≤ 0.8V; 10 µA

ENx

≥ 2.4V, (output off)

ENx

OFF Current in MIC2076 50 µA
Latched Thermal Shutdown (during thermal shutdown state)

Output Turn-On Delay RL = 10Ω, CL = 1µF, see “Timing Diagrams” 1.3 5 ms
Output Turn-On Rise Time RL = 10Ω, CL = 1µF, see “Timing Diagrams” 1.15 4.9 ms
Output Turnoff Delay RL = 10Ω, CL = 1µF, see “Timing Diagrams” 35 100 µs
Output Turnoff Fall Time RL = 10Ω, CL = 1µF, see “Timing Diagrams” 32 100 µs
Short-Circuit Output Current V

= 0V, enabled into short-circuit 0.5 0.9 1.25 A

OUT

Current-Limit Threshold ramped load applied to output 1.0 1.25 A
Short-Circuit Response Time V

OUT

= 0V to I

OUT

= I

LIMIT

20 µs

(short applied to output)
Overcurrent Flag Response VIN = 5V, apply V

Delay

VIN = 3.3V, apply V

= 0V until FLG low 1.5 3 7 ms

OUT

= 0V until FLG low TBD 3 ms

OUT

Undervoltage Lockout VIN rising 2.2 2.4 2.7 V
Threshold

VIN falling 2.0 2.15 2.5 V

March 2000 3 MIC2026/2076

MIC2026/2076 Micrel

Symbol Parameter Condition Min Typ Max Units

Error Flag Output IL = 10mA, VIN = 5V 10 25 Ω
Resistance

Error Flag Off Current V
Overtemperature Threshold T

Note 4

IL = 10mA, VIN = 3.3V 15 40 Ω

= 5V 10 µA

FLAG

increasing, each switch 140 °C

J

TJ decreasing, each switch 120 °C
T

increasing, both switches 160 °C

J

TJ decreasing, both switches 150 °C

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.
Note 4. If there is a fault on one channel, that channel will shut down when the die reaches approximately 140°C. If the die reaches approximately

160°C, both channels will shut down, even if neither channel is in current limit.

Test Circuit

V

Device
Under
Test

OUT

C

R

L

L

OUT

Timing Diagrams

t

R

V

OUT

90%

10%

90%

10%

t

F

Output Rise and Fall Times

V

EN

V

OUT

50%

t

OFF

t

ON

90%

10%

Active-Low Switch Delay Times (MIC20x6-2)

V

EN

50%

t

OFF

t

ON

V

OUT

90%

10%

Active-High Switch Delay Times (MIC20x6-1)

MIC2026/2076 4 March 2000

MIC2026/2076 Micrel

0

1

2

3

4

5

-40 -20 0 20 40 60 80 100

RISE TIME (ms)

TEMPERATURE (°C)

Turn-On Rise Time

vs. Temperature

RL=10Ω
C

L

=1µF

VIN = 5V

VIN = 3.3V

0

0.5

1.0

1.5

2.0

2.5

2.5 3.0 3.5 4.0 4.5 5.0 5.5

RISE TIME (ms)

INPUT VOLTAGE (V)

Turn-On Rise Time

vs. Input Voltage

RL=10Ω
C

L

=1µF

+85°C

+25°C

-40°C

0

100

200

300

400

-40 -20 0 20 40 60 80 100

FALL TIME (µs)

TEMPERATURE (°C)

Fall Time

vs. Temperature

RL=10Ω
C

L

=1µF

VIN = 3.3V

0

50

100

150

200

250

300

2.5 3.0 3.5 4.0 4.5 5.0 5.5

RISE TIME (µs)

INPUT VOLTAGE (V)

Fall Time

vs. Input Voltage

TA = 25°C

C

L

= 1µF

R

L

= 10Ω

Supply On-Current

180
160
140
120
100

CURRENT (µA)

vs. Temperature

5V

80

3.3V

60
40
20

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Supply On-Current

vs. Input Voltage

200

150

100

CURRENT (µA)

+85°C

50

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

INPUT VOLTAGE (V)

-40°C

+25°C

On-Resistance

160
140
120
100

ON-RESISTANCE (mΩ)

vs. Temperature

3.3V

I

OUT

5V

= 500mA

80
60
40
20

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

On-Resistance

200

150

100

RESISTANCE (mΩ)

vs. Input Voltage

+85°C
+25°C

50

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

-40°C

I

= 500mA

OUT

INPUT VOLTAGE (V)

CURRENT LIMIT (mA)

March 2000 5 MIC2026/2076

Short-Circuit Current-Limit

1000

800

600

400

200

vs. Temperature

VIN = 3.3V

VIN = 5V

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Short-Circuit Current-Limit

vs. Input Voltage

800
700
600
500
400
300
200

CURRENT LIMIT (mA)

100

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

+25°C

+85°C

INPUT VOLTAGE (V)

-40°C

Current-Limit Threshold

1200

1000

800

600

400

200

CURRENT LIMIT THRESHOLD (mA)

vs. Temperature

VIN = 5V

VIN = 3.3V

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Current-Limit Threshold

1200

1000

800

600

400

200

CURRENT LIMIT THRESHOLD (mA)

vs. Input Voltage

+25°C

+85°C

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

INPUT VOLTAGE (V)

-40°C

MIC2026/2076 Micrel

Enable Threshold

vs. Temperature

2.5

2.0

1.5

1.0

0.5

ENABLE THRESHOLD (V)

0

-40 -20 0 20 40 60 80 100

VEN RISING

VEN FALLING

VIN = 5V

TEMPERATURE (°C)

Enable Threshold

vs. Input Voltage

2.5

2.0

1.5

1.0

0.5

ENABLE THRESHOLD (V)

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

VEN RISING

VEN FALLING

TA = 25°C

INPUT VOLTAGE (V)

Flag Delay

vs. Temperature

5

4

3

2

DELAY TIME (ms)

1

0

-40 -20 0 20 40 60 80 100

VIN = 3.3V

VIN = 5V

TEMPERATURE (°C)

Flag Delay

vs. Input Voltage

5

+85°C

4

3

2

DELAY TIME (ms)

1

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

+25°C

-40°C

INPUT VOLTAGE (V)

Supply Off Current

vs. Temperature

5V

0.1

3.3V

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

0.16

0.14

0.12

0.08

0.06

0.04

0.02

Supply Off Current

vs. Input Voltage

+85°C

+25°C

-40°C

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

VOLTAGE (V)

SUPPLY CURRENT (µA)

0.18

0.16

0.14

0.12

0.10

0.08

0.06

0.04

0.02

UVLO Threshold
vs. Temperature

3.0

2.5

2.0

1.5

1.0

0.5

UVLO THRESHOLD (V)

0

-40 -20 0 20 40 60 80 100

VIN RISING

VIN FALLING

TEMPERATURE (°C)

MIC2026/2076 6 March 2000

MIC2026/2076 Micrel

Functional Characteristics

V

V

V

I

V

V

V

I

IN

FLG

OUT

OUT

EN

FLG

OUT

OUT

UVLO—VIN Rising

(MIC2026-1)

IN

V

V

(2V/div.)

FLG

(2V/div.)

2.4V

(2V/div.)

UVLO—VIN Falling

(MIC2026-1)

2.2V

(2V/div.)

VEN = V

IN

(2V/div.)

CL = 57µF

= 35Ω

R

L

V

I

OUT

OUT

(5V/div.)

VEN = V

IN

CL = 57µF

= 35Ω

R

L

(100mA/div.)

(100mA/div.)

TIME (10ms/div.)

Turn-On/Turnoff

(MIC2026-1)

EN

V

V

V

I

(10V/div.)

FLG

(5V/div.)

OUT

(5V/div.)

OUT

(200mA/div.)

(10V/div.)

(5V/div.)

(5V/div.)

712mA
(Inrush Current)

VIN = 5V

= 147µF

C

L

= 35Ω

R

L

140mA

(200mA/div.)

TIME (100ms/div.)

Turn-On

(MIC2026-1)

VIN = 5V

= 147µF

C

L

= 35Ω

R

L

140mA

V

V

V

I

EN

FLG

OUT

OUT

TIME (10ms/div.)

Turnoff

(MIC2026-1)

EN

(10V/div.)

(5V/div.)

(5V/div.)

VIN = 5V

= 147µF

C

L

= 35Ω

R

140mA

L

V

V

V

I

(10V/div.)

FLG

(5V/div.)

OUT

(5V/div.)

OUT

TIME (500µs/div.)

Enabled Into Short

(MIC2026-1)

3.1ms (tD)

700mA

VIN = 5V

(500mA/div.)

(200mA/div.)

TIME (5ms/div.)

TIME (500µs/div.)

March 2000 7 MIC2026/2076

MIC2026/2076 Micrel

V

V

I

V

V

V

EN

FLG

OUT

EN

FLG

OUT

Inrush Current Response

(MIC2026-1)

IN

(10V/div.)

(5V/div.)

CL = 110µF

CL = 210µF

CL = 310µF

VIN = 5V

= 31Ω

R

L

(200mA/div.)

= 10µF

C

L

V

V

V

I

(10V/div.)

FLG

(10V/div.)

OUT

(5V/div.)

OUT

(500mA/div.)

Current-Limit
Threshold
(1A)

TIME (1ms/div.)

Current-Limit Response

(Stepped Short—MIC2026-1)

(10V/div.)

(5V/div.)

VIN = 5V

= 47µF

C

L

= stepped short

R

L

V

OUT

(5V/div.)

Current-Limit Response

(Ramped Load–MIC2026-1)

Short-Circuit
Current (800mA)

Thermal Shutdown

Thermal
Shutdown
Hysteresis

TIME (100ms/div.)

Current-Limit Response

(MIC2026-1)

VIN = 5V

= 0

C

L

= stepped short

R

L

VIN = 5V
C

L

Short
Removed

= 47µF

(5V/div.)

OUT

I

ENB

V

FLGA

V

FLGB

V

OUTB

I

OUT

I

ENA

V

FLGA

V

FLGB

V

(5A/div.)

TIME (50µs/div.)

Independent Thermal Shutdown

(MIC2026-1)

(10V/div.)

(5V/div.)

(5V/div.)

(2A/div.)

800mA

TIME (1ms/div.)

Independent Thermal Shutdown

(MIC2026-1)

(10V/div.)

V

= No Load

(5V/div.)

OUTA

(No Thermal Shutdown)

Short-Circuit (800mA)

V

= No Load

OUTB

(No Thermal Shutdown)

(5V/div.)

Thermal Shutdown

OUTA

I

Thermal Shutdown

(500mA/div.)

(500mA/div.)

TIME (100ms/div.)

TIME (100ms/div.)

MIC2026/2076 8 March 2000

MIC2026/2076 Micrel

Thermal Shutdown

(MIC2076-2—Output Latched Off)

Thermal
Shutdown

TIME (2.5s/div.)

Load Removed

Output
Reset

VIN = 5V
C
V

FLG

V

OUT

V

OUTB

I

RL = 0

(10V/div.)

(5V/div.)

(500mV/div.)

Thermal Shutdown

(Output Reset by Removing Load—MIC2076-2)

EN

V

(10V/div.)

V

V

I

FLG

(5V/div.)

OUT

(5V/div.)

OUT

(500mA/div.)

Output
Latched Off

Ramp Load
to Short

Thermal
Shutdown

VIN = 5V
C

No Load

= 47µF

L

= 0V

ENB

Load Removed
(Output Reset)

= 47µF

L

(Output Reset by Toggling Enable—MIC2076-2)

Thermal Shutdown

EN

V

(10V/div.)

FLG

V

V

I

(5V/div.)

OUT

(5V/div.)

OUT

C

L

R

L

= 57µF
= 35Ω

Ramp Load
to Short

Thermal
Shutdown

VIN = 5V

(500mA/div.)

TIME (100ms/div.)

Independent Thermal Shutdown

(MIC2076-2)

R

= 0

FLGB

V

FLGA

V

OUTA

I

L

No Thermal Shutdown on Channel B

(5V/div.)

(5V/div.)

Thermal
Shutdown

(500mA/div.)

Load
Removed

Output Reset

VIN = 5V
C
V
V

Enable
Reset

Output
Reset

No
Load

= 47µF

L

= 0V

ENB

= 0V

ENA

TIME (100ms/div.)

FLGB

V

FLGA

V

OUTB

I

TIME (2.5s/div.)

Independent Thermal Shutdown

(MIC2076-2)

Load

RL = 0

Removed

(10V/div.)

No Thermal Shutdown on Channel A

(5V/div.)

Thermal
Shutdown

(500mA/div.)

TIME (2.5s/div.)

No
Load

Output Reset

VIN = 5V
C
V
V

= 47µF

L
ENB
ENA

= 0V
= 0V

March 2000 9 MIC2026/2076

MIC2026/2076 Micrel

Block Diagram

FLGA

FLAG

RESPONSE

ENA

CHARGE

PUMP

GATE

CONTROL

DELAY

CURRENT

LIMIT

OUTA

THERMAL

SHUTDOWN

ENB

MIC2026/2076

OSC.

CHARGE

PUMP

Functional Description

Input and Output

IN is the power supply connection to the logic circuitry and the
drain of the output MOSFET. OUT is the source of the output
MOSFET. In a typical circuit, current flows from IN to OUT
toward the load. If V
from OUT to IN, since the switch is bidirectional when
enabled. 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
switch is disabled. In this situation, the MIC2026/76 prevents
undesirable current flow from OUT to IN.

Thermal Shutdown

Thermal shutdown is employed to protect the device from
damage should the die temperature exceed safe margins
due mainly to short circuit faults. Each channel employs its
own thermal sensor. Thermal shutdown shuts off the output
MOSFET and asserts the FLG output if the die temperature
reaches 140°C and the overheated channel is in current limit.
The other channel is not effected. If however, the die tem­perature exceeds 160°C, both channels will be shut off. Upon
determining a thermal shutdown condition, the MIC2076 will
latch the output off. In this case, a pull-up current source is
activated. This allows the output latch to automatically reset
when the load (such as a USB device) is removed. The output
can also be reset by toggling EN. Refer to Figure 1 for timing
details.

is greater than VIN, current will flow

OUT

> VIN) when the

OUT

GND

UVLO

REFERENCE

GATE

CONTROL

1.2V

RESPONSE

DELAY

CURRENT

LIMIT

FLAG

IN

OUTB

FLGB

The MIC2026 will automatically reset its output when the die
temperature cools down to 120°C. The MIC2026 output and
FLG signal will continue to cycle on and off until the device is
disabled or the fault is removed. Figure 2 depicts typical
timing.

Depending on PCB layout, package, ambient temperature,
etc., it may take several hundred milliseconds from the
incidence of the fault to the output MOSFET being shut off.
This time will be shortest in the case of a dead short on the
output.

Power Dissipation

The device’s junction temperature depends on several fac­tors such as the load, PCB layout, ambient temperature and
package type. Equations that can be used to calculate power
dissipation of each channel and junction temperature are
found below.

PD = R

DS(on)

× I

OUT

2

Total power dissipation of the device will be the summation of
PD for both channels. To relate this to junction temperature,
the following equation can be used:

TJ = PD × θJA + T

A

where:

TJ = junction temperature
TA = ambient temperature

θJA = is the thermal resistance of the package

MIC2026/2076 10 March 2000

MIC2026/2076 Micrel

Current Sensing and Limiting

The current-limit threshold is preset internally. The preset
level prevents damage to the device and external load but still
allows a minimum current of 500mA to be delivered to the
load.

The current-limit circuit senses a portion of the output MOS­FET 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 enabled into a heavy load or short-circuit, the
switch immediately enters into a constant-current mode,
reducing the output voltage. The FLG signal is asserted
indicating an overcurrent condition.

Short-Circuit Applied to Enabled Output

When a heavy load or short-circuit is applied to an enabled
switch, a large transient current may flow until the current­limit circuitry responds. Once this occurs the device limits
current to less than the short-circuit current limit specification.

Current-Limit Response—Ramped Load

The MIC2026/76 current-limit profile exhibits a small foldback
effect of about 200mA. Once this current-limit threshold is
exceeded the device switches into a constant current mode.
It is important to note that the device will supply current up to
the current-limit threshold.

Fault Flag

The FLG signal is an N-channel open-drain MOSFET output.
FLG is asserted (active-low) when either an overcurrent or
thermal shutdown condition occurs. In the case of an overcur­rent condition, FLG will be asserted only after the flag
response delay time, t

, has elapsed. This ensures that FLG

D

is asserted only upon valid overcurrent conditions and that
erroneous error reporting is eliminated. For example, false
overcurrent conditions can occur during hot-plug events
when a highly capacitive load is connected and causes a high
transient inrush current that exceeds the current-limit thresh­old for up to 1ms. The FLG response delay time t

is typically

D

3ms.

Undervoltage Lockout

Undervoltage lockout (UVLO) prevents the output MOSFET
from turning on until VIN exceeds approximately 2.5V. Under­voltage detection functions only when the switch is enabled.

Load and Fault Removed

(Output Reset)

V

V

OUT

I

LIMIT

I

LOAD

I

OUT

V

EN

FLG

Short-Circuit Fault

Thermal

Shutdown

Reached

3ms typ.

delay

Figure 1. MIC2076-2 Fault Timing: Output Reset by Removing Load

V

V

OUT

I

LIMIT

I

LOAD

I

OUT

V

FLG

EN

3ms typ.

delay

Short-Circuit Fault

Load/Fault

Removed

Thermal

Shutdown

Reached

Figure 2. MIC2026-2 Fault Timing

March 2000 11 MIC2026/2076

MIC2026/2076 Micrel

Applications Information

Supply Filtering

A 0.1µF to 1µF bypass capacitor positioned close to VIN and
GND of 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.

Printed Circuit Board Hot-Plug

The MIC2026/76 are ideal inrush current-limiters for hot-plug
applications. Due to the integrated charge pump, the
MIC2026/76 presents a high impedance when off and slowly
becomes a low impedance as it turns on. This “soft-start”
feature effectively isolates power supplies from highly ca­pacitive loads by reducing inrush current. Figure 3 shows how
the MIC2076 may be used in a card hot-plug application.

In cases of extremely large capacitive loads (>400µF), the
length of the transient due to inrush current may exceed the
delay provided by the integrated filter. Since this inrush
current exceeds the current-limit delay specification, FLG will
be asserted during this time. To prevent the logic controller
from responding to FLG being asserted, an external RC filter,
as shown in Figure 4, can be used to filter out transient FLG
assertion. The value of the RC time constant should be
selected to match the length of the transient, less t
MIC2026/76.

D(min)

of the

Universal Serial Bus (USB) Power Distribution

The MIC2026/76 is ideally suited for USB (Universal Serial
Bus) power distribution applications. The USB specification
defines power distribution for USB host systems such as PCs
and USB hubs. Hubs can either be self-powered or bus­powered (that is, powered from the bus). Figure 5 shows a
typical USB Host application that may be suited for mobile PC
applications employing USB. The requirement for USB host
systems is that the port must supply a minimum of 500mA at
an output voltage of 5V ±5%. In addition, the output power
delivered must be limited to below 25VA. Upon an overcurrent
condition, the host must also be notified. To support hot-plug
events, the hub must have a minimum of 120µF of bulk
capacitance, preferably low ESR electrolytic or tantulum.
Please refer to Application Note 17 for more details on
designing compliant USB hub and host systems.

For bus-powered hubs, USB requires that each downstream
port be switched on or off under control by the host. Up to four
downstream ports each capable of supplying 100mA at 4.4V
minimum are allowed. In addition, to reduce voltage droop on
the upstream V

, soft-start is necessary. Although the hub

BUS

can consume up to 500mA from the upstream bus, the hub
must consume only 100mA max at start-up, until it enumer­ates with the host prior to requesting more power. The same
requirements apply for bus-powered peripherals that have no
downstream ports. Figure 6 shows a bus-powered hub.

V

BUS

to "Hot"
Receptacle

GND

Cable

Logic Controller

OVERCURRENT

MIC2026-2BM

18

ENA OUTA

27

FLGA

4.7
µF

36

FLGB GND

4

ENB

USB Peripheral

OUTB

IN

5

Figure 3. Hot-Plug Application

V+

10k

R

C

MIC2026

18

EN OUTA

27

FLGA

36

FLGB GND

45

ENB OUTB

USB

Controller

USB

Function

C

BULK

USB

Function

C

BULK

IN

Figure 4. Transient Filter

MIC2026/2076 12 March 2000

MIC2026/2076 Micrel

V

CC

4.50V to 5.25V
Upstream V

100mA max.

BUS

V

D+

D–

GND

BUS

Data

1µF

MIC5207-3.3

IN OUT

GND

VIN

OVERCURRENT

1µF

OVERCURRENT

10k
10k

ON/OFF

ON/OFF

MIC2026-23.3V USB Controller

ENA OUTA
FLGA IN
FLGB GND
ENB OUTB

5.0V

47µF

0.1µF

47µF

Ferrite
Beads

Data

(Two Pair)

to USB

Controller

V

BUS

D+

D–

GND

V

BUS

D+

D–

GND

USB

Port 1

USB

Port 2

4.50V to 5.25V
Upstream V

BUS

V

D+

D–

GND

BUS

Data

1µF

1.5k 2%

MIC5207-3.3

IN OUT

GND

Figure 5. USB Two-Port Host Application

10k
10k

MIC2026-23.3V USB Controller

VIN

OVERCURRENT

1µF

OVERCURRENT

ON/OFF

ON/OFF

ENA OUTA
FLGA IN
FLGB GND
ENB OUTB

Figure 6. USB Two-Port Bus-Powered Hub

0.1µF

47µF

47µF

Ferrite
Beads

Data

(Two Pair)

to USB

Controller

V

BUS

D+

D–

GND

V

BUS

D+

D–

GND

USB

Port 1

USB

Port 2

March 2000 13 MIC2026/2076

MIC2026/2076 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)

DIMENSIONS:

INCHES (MM)

0.020 (0.51)

0.013 (0.33)

0.0098 (0.249)

0.0040 (0.102)

0°–8°

SEATING

PLANE

8-Lead SOP (M)

PIN 1

DIMENSIONS:

0.050 (1.27)

0.016 (0.40)

0.244 (6.20)

0.228 (5.79)

INCH (MM)

45°

0.010 (0.25)

0.007 (0.18)

0.018 (0.57)

0.100 (2.54)

0.380 (9.65)

0.370 (9.40)

0.135 (3.43)

0.125 (3.18)

0.130 (3.30)

0.0375 (0.952)

8-Pin DIP (N)

0.255 (6.48)

0.245 (6.22)

0.300 (7.62)

0.013 (0.330)

0.010 (0.254)

0.380 (9.65)

0.320 (8.13)

MIC2026/2076 14 March 2000

MIC2026/2076 Micrel

March 2000 15 MIC2026/2076

MIC2026/2076 Micrel

MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL + 1 [phone] FAX + 1 [phone] 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

MIC2026/2076 16 March 2000