MIC2005/2015
Fixed Current Limit
Power Distribution Switch
Kickstart is a trademark of Micrel, Inc
MLF and
Micro
LeadFrame are trademarks of Amkor Technology, Inc.
Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 http://www.micrel.com
General Description
The MIC2005 and MIC2015 are current limiting, high-
side power switches, designed for general purpose
power distribution and control in PCs, PDAs, printers
and other self-powered systems.
The MIC2005 and MIC2015's primary functions are
current limiting and power switching. They are thermally
protected and will shut down should their internal
temperature reach unsafe levels, protecting both the
device and the load, under high current or fault
conditions.
Features include fault reporting, with fault blanking to
eliminate noise-induced false alarms, output slew rate
limiting and under voltage detection. Both devices are
fully self-contained, with the current limit value being
factory set to one of several convenient levels.
The MIC2015 offers a unique new feature: Kickstart
TM
,
which allows momentary high current surges to pass
unrestricted without sacrificing overall system safety.
The MIC2005 and MIC2015 are excellent choices for
USB and IEEE 1394 (FireWire) applications or for any
system where current limiting and power control are
desired.
The MIC2005 and MIC2015 are offered in space saving
6 pin SOT-23 and 2mm x 2mm MLF packages.
Data sheets and support documentation can be found
on Micrel's web site at: www.micrel.com.
Features
70m typical on-resistance
2.5V - 5.5V operating range
Pre-set current limit values: 0.5A, 0.8A and 1.2A
Kickstart
TM
Fault status flag
Fault masking: prevents nuisance alarms on current
surges or hot plug events
Thermal Protection
Under voltage lock-out
Adjustable slew rate limited Turn-ON
Low quiescent current
Applications
USB / IEEE 1394 Power Distribution
Desktop and Laptop PCs
Set top boxes
Game
consoles
PDAs
Printers
Docking stations
Chargers
_________________________________________________________________________________________________________
Typical Application
VIN
D+/D-
D+/D-
5V Supply
CSLEW
VOUT
GND
ENABLE FAULT/
MIC2005
MIC2015
USB
Controller
V
BUS
V
BUS
USB
Port
USB
Port
Figure 1. Typical Application Circuit
August 2005
M9999-080305
(408) 955-1690
Micrel
MIC2005/MIC2015
August 2005
2
M9999-080305
(408) 955-1690
MIC2000 Family Members
Part Number
Pin Function
Normal Limiting
Kickstart
I Limit
I Adj.
Enable
C
SLEW
FAULT/ DLM*
Load
Discharge
2003 2013
--
--
--
--
--
--
2004 2014
--
-- -- --
2005 2015
--
-- --
2006 2016
Fixed
--
-- --
2007 2017
-- --
2008 2018
-- -- --
2009 2019
Adj.
-- -- --
* Dynamic Load Management Adj = Adjustable current limit
Fixed = Factory programmed current limit
Ordering Information
Part Number
Marking
(1)
Current Limit
Kickstart
Pb-Free
Package
MIC2005-0.5YM6
FF05 0.5A
MIC2005-0.8YM6
FF08 0.8A
MIC2005-1.2YM6
FF12 1.2A
SOT-23-6
MIC2005-0.5YML
(2)
F05 0.5A
MIC2005-0.8YML
(2)
F08 0.8A
MIC2005-1.2YML
(2)
F12 1.2A
No
2mmX2mm MLF
MIC2015-0.5YM6
FN05 0.5A
MIC2015-0.8YM6
FN08 0.8A
MIC2015-1.2YM6
FN12 1.2A
SOT-23-6
MIC2015-0.5YML
(2)
N05 0.5A
MIC2015-0.8YML
(2)
N08 0.8A
MIC2015-1.2YML
(2)
N12 1.2A
Yes
Yes
2mmX2mm MLF
Notes:
1. Under-bar symbol ( _ ) may not be to scale.
2. Contact factory for availability.
Micrel
MIC2005/MIC2015
August 2005
3
M9999-080305
(408) 955-1690
Pin Configuration
N
O
D
A
P
E
D
I
S
K
C
A
B
D
N
U
O
R
G
S
I
V
OUT
1
2
3
4
5
6
C
SLEW
FAULT/
V
IN
GND
ENABLE
6-Lead 2mm x 2mm MLF (ML)
Top View
V
OUT
C
SLEW
FAULT/
V
IN
GND
ENABLE
3
1
6
2
4
5
SOT 23-6 (M6)
Top View
Pin Description
Pin
Number
SOT-23
Pin
Number
MLF
Pin
Name
Type Description
1 6
VIN
Input
Supply input. This pin provides power to both the output switch and the
MIC2005/2015's internal control circuitry.
2 5
GND
--
Ground.
3 4
ENABLE
Input
Output enable pin. A logic HIGH activates the output switch, applying power to
the load attached to V
OUT
.
4 3
FAULT/
Output
Fault status. A logic LOW on this pin indicates the MIC2005/2015 is in current
limiting, or has been shut down by the thermal protection circuit. This is an
`Open Drain' output allowing logical OR'ing of multiple MIC2005/2015s.
5 2
CSLEW
Input
Slew rate control. Adding a small value capacitor between this pin and VIN
slows turn-ON of the power FET.
6 1
VOUT
Output
Switch output. The load being driven by MIC2005/2015 is connected to this
pin.
Micrel
MIC2005/MIC2015
August 2005
4
M9999-080305
(408) 955-1690
Absolute Maximum Ratings
(1)
V
IN
, V
OUT
............................................................ 0.3 to 6V
All other pins.................................................. 0.3 to 5.5V
Power Dissipation.................................. Internally Limited
Continuous Output Current..................................... 2.25A
Maximum Junction Temperature........................... 150
C
Storage Temperature .............................. 65
C to 150C
Operating Ratings
(2)
Supply Voltage............................................. 2.5V to 5.5V
Continuous Output Current Range .................... 0 to 2.1A
Ambient Temperature Range ....................40
C to 85C
Package Thermal Resistance (
JA
)
SOT-23-6
.............................................
230C/W
MLF 2x2 mm............................................ 90C/W
MLF 2x2 mm
JC
(5)
.................................. 45C/W
Electrical Characteristics
V
IN
= 5V, T
AMBIENT
= 25
C unless specified otherwise. Bold indicates 40C to +85C limits.
Symbol Parameter
Conditions
Min
Typ
Max
Units
V
IN
Switch Input Voltage
2.5
5.5
V
I
IN
Internal Supply Current
Switch = OFF,
ENABLE = 0V
1 5
A
I
IN
Internal Supply Current
Switch = ON, I
OUT
= 0
ENABLE = 1.5V
80
330
A
I
LEAK
Output Leakage Current
V
IN
= 5V, V
OUT
= 0 V,
ENABLE = 0
12
100
A
70
100
m
R
DS(ON)
Power Switch Resistance
V
IN
= 5V, I
OUT
= 100 mA
125
m
I
LIMIT
Current Limit: 0.5
V
OUT
= 0.8V
IN
0.5
0.7 0.9 A
I
LIMIT
Current Limit: 0.8
V
OUT
= 0.8V
IN
0.8
1.1 1.5 A
I
LIMIT
Current Limit: 1.2
V
OUT
= 0.8V
IN
1.2
1.6 2.1 A
I
LIMIT_2nd
Secondary current limit
(Kickstart)
MIC2015, V
IN
= 2.5V
2.2
4
6
A
V
IN
rising
2.0
2.25
2.5
V
UVLO
THRESHOLD
Under Voltage Lock Out
threshold
V
IN
falling
1.9
2.15
2.4
V
V
IL
(max.)
0.5
V
EN
ENABLE Input Voltage
V
IH
(min.)
1.5
V
I
EN
ENABLE Input Current
V
EN
= 0V to 5.0V
1
5
A
V
FAULT
Fault status Output Voltage
I
OL
= 10mA
.25
0.4
V
T
J
increasing
145
OT
THRESHOLD
Over-temperature Threshold
T
J
decreasing
135
C
Micrel
MIC2005/MIC2015
August 2005
5
M9999-080305
(408) 955-1690
AC Characteristics
Symbol Parameter
Condition
Min
Typ
Max
Units
t
RISE
Output turn-ON rise time
R
L
= 10
, C
LOAD
= 1
F,
V
OUT
= 10% to 90%
500 1000 1500
s
Time from current limiting to
FAULT/ state change.
MIC2005
20
32
49
ms
t
D_FAULT
Delay before asserting or
releasing FAULT/
Time from Iout continuously
exceeding primary current limit
condition to FAULT/ state
change.
MIC2015
77
128
192
ms
t
D_LIMIT
Delay before current limiting
MIC2015
77
128
192
ms
t
RESET
Delay before resetting
Kickstart current limit delay,
t
D_LIMIT
Out of current limit following a
current limit event.
(MIC2015 only)
77
128
192
ms
t
ON_DLY
Output Turn-on Delay
R
L
= 43
, C
L
= 120F,
C
SLEW
10pF,
V
EN
= 50% to V
OUT
= 10%
1000
1500
s
t
OFF_DLY
Output Turn-off Delay
R
L
= 43
, C
L
= 120F,
C
SLEW
10pF,
V
EN
= 50% to V
OUT
= 90%
700
s
ESD
Symbol Parameter
Condition
Min
Typ
Max
Units
V
OUT
and GND
4
kV
V
ESD_HB
Electro Static Discharge
Voltage: Human Body Model
All other pins
2
kV
V
ESD_MCHN
Electro Static Discharge
Voltage; Machine Model
All pins
Machine Model
200
V
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
5. Requires proper thermal mounting to achieve this performance.
Micrel
MIC2005/MIC2015
August 2005
6
M9999-080305
(408) 955-1690
Timing Diagrams
ENABLE
VOUT
50%
90%
10%
t
ON_DLY
t
OFF_DLY
50%
Switching Delay Times
90%
10%
90%
10%
t
FALL
t
RISE
Rise and Fall Times
90%
10%
t
RISE
VOUT
Output Rise Time
Micrel
MIC2005/MIC2015
August 2005
7
M9999-080305
(408) 955-1690
Typical Characteristics
0
20
40
60
80
100
2
3
4
5
6
SUP
P
LY CUR
RENT
(
A)
V
IN
(V)
Supply Current
Output Enabled
-40C
85C
25C
0
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
2
3
4
5
6
7
SUP
P
L
Y
CURRE
N
T
(
A)
V
IN
(V)
Supply Current
Output Disabled
-40C
85C
25C
0
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
-50 -30 -10 10 30 50 70 90
(
A)
TEMPERATURE (C)
Switch Leakage Current - OFF
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
-50 -30 -10 10 30 50 70 90
I
LI
MI
T
(A)
TEMPERATURE (C)
I
LIMIT
vs.
Temperature
1.2A
0.8A
0.5A
1.25
1.30
1.35
1.40
1.45
1.50
1.55
1.60
1.65
-50 -30 -10 10 30 50 70 90
I
LI
M
I
T
(A
)
TEMPERATURE (C)
I
LIMIT
vs. Temperature
(MIC20xx-1.2)
V
IN
= 2.5V
V
IN
= 5V
V
IN
= 3V
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
-50 -30 -10 10 30 50 70 90
I
LI
M
I
T
(A)
TEMPERATURE (C)
5V
3V
2.5V
I
LIMIT
vs. Temperature
(MIC20xx - 0.8)
Please note that
the 3 plots
overlay each
other.
0.55
0.57
0.59
0.61
0.63
0.65
0.67
0.69
0.71
0.73
0.75
-50 -30 -10 10 30 50 70 90
I
LI
MI
T
(A
)
TEMPERATURE (C)
5V
3V
2.5V
I
LIMIT
vs. Temperature
(MIC20xx - 0.5)
0
20
40
60
80
100
2
2.5
3
3.5
4
4.5
5
5.5
R
ON
(mOhm)
V
IN
(V)
R
ON
vs.
Supply Voltage
0
20
40
60
80
100
120
-50 -30 -10 10 30 50 70 90
R
ON
(mOhm)
TEMPERATURE (C)
R
ON
vs.
Temperature
2.5V
3.3V
5V
2.05
2.1
2.15
2.2
2.25
2.3
-50
0
50
100
150
TH
RESH
O
L
D (
V
)
TEMPERATURE (C)
UVLO Threshold
vs. Temperature
V RISING
V FALLING
Micrel
MIC2005/MIC2015
August 2005
8
M9999-080305
(408) 955-1690
Functional Characteristics
FAULT/
(2.5V/div)
ENABLE
(2.5V/div)
V
OUT
(1V/div)
I
OUT
(150mA/div)
0
Time (s)
2000
6000
10000
14000
18000
22000
C
SLEW
Response
V
IN
= 5.0V
R
LOAD
C
LOAD
= 0F
0pF 100pF
820pF
1800pF
2700pF 3500pF
FAULT/
(2.5V/div)
ENABLE
(2.5V/div)
V
OUT
(1V/div)
I
OUT
(250mA/div)
0
Time (ms)
50
100
150
200
250
300
350
400
450
500
550
Current Limit Response Thermal Shutdown
V
IN
= 5.0V
R
LOAD
C
LOAD
= 47F
FAULT/
(2.5V/div)
ENABLE
(2.5V/div)
V
OUT
(1V/div)
I
OUT
(0.5A/div)
0
Time (ms)
50
100
150
200
250
300
350 400 450 500
550
Kickstart Response
Normal Load with Temporary High Load
FAULT/
(1V/div)
ENABLE
(1V/div)
V
OUT
(1V/div)
I
OUT
(0.5A/div)
0
Time (ms)
50
100
150
200
250
300
350
400
450 500
550
Kickstart Response
No Load to Short Circuit
FAULT/
(2.5V/div)
ENABLE
(2.5V/div)
V
OUT
(1V/div)
I
OUT
(0.5A/div)
0
Time (ms)
50
100
150
200
250
300
350
400 450 500
550
Kickstart Response
Normal Load with Temporary Short Circuit
FAULT/
(2.5V/div)
ENABLE
(2.5V/div)
V
OUT
(1V/div)
I
OUT
(0.5A/div)
0
Time (ms)
50
100
150
200
250
300
350
400 450 500
550
Kickstart Response
Device Enabled into a Short Circuit
Micrel
MIC2005/MIC2015
August 2005
9
M9999-080305
(408) 955-1690
FAULT/
(2.5V/div)
ENABLE
(2.5V/div)
V
OUT
(1V/div)
I
OUT
(200mA/div)
0
Time (ms)
R
L
C
SLEW
= 0pF
4
8
12
16
20
24
28
32
36
40
Inrush Current Response
MIC20xx-0.5
0F
10F
22F47F 100F
220F
470F
FAULT/
(2.5V/div)
ENABLE
(2.5V/div)
V
OUT
(1V/div)
I
OUT
(200mA/div)
0
Time (ms)
2
4
6
8
10
12
14
V
IN
= 5.0V
R
LOAD
C
LOAD
= 100F
C
SLEW
= 0pF
Turn-On/Turn-Off
FAULT/
(2.5V/div)
ENABLE
(2.5V/div)
V
OUT
(1V/div)
V
IN
(1/div)
0
Time (s)
4
8
12
16
20
24
28
32
36
40
44
48
UVLO Increasing
Enable tied to V
IN
FAULT/
(2.5V/div)
ENABLE
(2.5V/div)
V
OUT
(1V/div)
V
IN
(1/div)
0
Time (s)
Enable tied to V
IN
4
8
12
16
20
24
28
32
36
40
44
48
UVLO Decreasing
Micrel
MIC2005/MIC2015
August 2005
10
M9999-080305
(408) 955-1690
Functional Diagram
V
F
E
R
r
e
w
o
P
T
E
F
r
e
d
n
U
e
g
a
tl
o
V
r
o
t
c
e
t
e
D
l
a
m
r
e
h
T
r
o
s
n
e
S
e
t
a
R
w
e
l
S
l
o
r
t
n
o
C
t
n
e
r
r
u
C
T
E
F
r
o
r
ri
M
y
r
o
t
c
a
F
d
e
t
s
u
j
d
a
ti
m
i
L
t
n
e
r
r
u
C
p
o
o
L
l
o
r
t
n
o
c
l
o
r
t
n
o
C
e
t
a
G
c
i
g
o
L
l
o
r
t
n
o
C
r
e
m
i
T
y
a
l
e
D
d
n
a
ENABLE
FAULT/
CSLEW
GND
VOUT
VIN
Figure 2. MIC2005/2015 Block Diagram
Micrel
MIC2005/MIC2015
August 2005
11
M9999-080305
(408) 955-1690
Functional Description
Input and Output
V
IN
is both the power supply connection for the internal
circuitry driving the switch and the input (Source
connection) of the power MOSFET switch. V
OUT
is the
Drain connection of the power MOSFET and supplies
power to the load. In a typical circuit, current flows from
V
IN
to V
OUT
toward the load. Since the switch is bi-
directional when enabled, if V
OUT
is greater than V
IN
,
current will flow from V
OUT
to V
IN
.
When the switch is disabled, current will not flow to the
load, except for a small unavoidable leakage current of
a few microamps. However, should V
OUT
exceed V
IN
by
more than a diode drop (~0.6V), while the switch is
disabled, current will flow from output to input via the
power MOSFET's body diode. This effect can be used
to advantage when large bypass capacitors are placed
on MIC2005/2015's's output. When power to the switch
is removed, the output capacitor will be automatically
discharged.
If discharging C
LOAD
is required by your application,
consider using MIC2004/2014 or MIC2007/2017 in place
of MIC2005/2015. These MIC2000 family members are
equipped with a discharge FET to insure complete
discharge of C
LOAD
.
Current Sensing and Limiting
The MIC2005/2015 protects the system power supply
and load from damage by continuously monitoring
current through the on-chip power MOSFET. Load
current is monitored by means of a current mirror in
parallel with the power MOSFET switch. Current limiting
is invoked when the load exceeds an internally set over-
current threshold. When current limiting is activated, the
output current is constrained to the limit value, and
remains at this level until either the load/fault is
removed, the load's current requirement drops below
the limiting value, or the MIC2005/2015 goes into
thermal shutdown.
Kickstart (MIC2015 only)
The MIC2015 is designed to allow momentary current
surges (Kickstart) before the onset of current limiting,
which permits dynamic loads, such as small disk drives
or portable printers to draw the energy needed to
overcome inertial loads without sacrificing system
safety. In this respect, the MIC2015 differs markedly
from MIC2005 and its peers, which immediately limit
load current, potentially starving the motor and causing
the appliance to stall or stutter.
During this delay period, typically 128 ms, a secondary
current limit is in effect. If the load demands a current in
excess of the secondary limit, MIC2015 acts
immediately to restrict output current to the secondary
limit for the duration of the Kickstart period. After this
time, the MIC2015 reverts to its normal current limit. An
example of Kickstart operation is shown below.
T
U
O
T
U
O
Figure 3. Kickstart Operation
Picture Key:
A) MIC2015 is enabled into an excessive load (slew
rate limiting not visible at this time scale) The initial
current surge is limited by either the overall circuit
resistance and power supply compliance, or the
secondary current limit, whichever is less.
B) R
ON
of the power FET increases due to internal
heating (effect exaggerated for emphasis).
C) Kickstart period.
D) Current limiting initiated. FAULT/ goes LOW.
E) V
OUT
is non-zero (load is heavy, but not a dead short
where V
OUT
= 0. Limiting response will be the same
for dead shorts).
F) Thermal shutdown followed by thermal cycling.
G) Excessive load released, normal load remains.
MIC2015 drops out of current limiting.
H) FAULT/ delay period followed by FAULT/ going
HIGH.
Under Voltage Lock Out
Under voltage lock-out insures no anomalous operation
occurs before the device's minimum input voltage of
2.5V had been achieved. Prior to reaching this voltage,
the output switch (power MOSFET) is OFF and no
circuit functions, such as FAULT/ or ENABLE, are
considered to be valid or operative.
Micrel
MIC2005/MIC2015
August 2005
12
M9999-080305
(408) 955-1690
Enable
ENABLE is a HIGH true control signal, which activates
the main MOSFET switch. ENABLE will operate with
logic running from supply voltages as low as 1.8V.
ENABLE can be wire-OR'd with other MIC2005/2015s
or similar devices without damage to the device.
ENABLE may be driven higher than V
IN
, but no higher
than 5.5V.
FAULT/
FAULT/ is an N-channel `open drain' output, which is
asserted (LOW true) when MIC2005/2015's either
begins current limiting or enters thermal shutdown.
In MIC2005, FAULT/ asserts after a brief delay period,
usually 32 ms. This delay ensures that FAULT/ is
asserted only upon valid, enduring, over-current
conditions and that transitory event error reports are
filtered out.
MIC2015's FAULT/ asserts at the end of the Kickstart
period. This masks initial current surges, such as would
be seen by a motor load starting up. If the load current
remains above the current limit threshold after the
Kickstart has timed out, then FAULT/ will be asserted.
After a fault clears, FAULT/ remains asserted for the
delay period; 32ms for the MIC2005 or 128 ms for the
MIC2015.
Because FAULT/ is an `open drain' it must be pulled
HIGH with an external resistor output and it may be
wire-OR'd with other similar outputs, sharing a single
pull-up resistor. FAULT/ may be tied to a pull-up voltage
source which is higher than V
IN
, but no greater than
5.5V.
Slew Rate Control
Large capacitive loads can create significant current
surges when charged through a high-side switch such
as the MIC2005/2015. For this reason, the
MIC2005/2015 provides built-in slew rate control to limit
the initial inrush currents upon enabling the power
MOSFET switch.
Slew rate control is active upon powering up, and upon
re-enabling the load. At shutdown, the discharge slew
rate is controlled by the external load and output
capacitor.
On MIC2005/2015 Slew Rate is adjustable and can be
further reduced by adding an external capacitance
between VIN and the CSLEW pins.
Thermal Shutdown
Thermal shutdown is employed to protect the
MIC2005/2015 from damage should the die temperature
exceed safe operating levels. Thermal shutdown shuts
off the output MOSFET and asserts the FAULT/ output if
the die temperature reaches 145C.
The MIC2005/2015 will automatically resume operation
when the die temperature cools down to 135C. If
resumed operation results in reheating of the die,
another shutdown cycle will occur and the
MIC2005/2015 will continue cycling between ON and
OFF states until the offending load has been removed.
Depending upon PCB layout, package type, ambient
temperature, etc., hundreds of milliseconds may elapse
from the incidence of a fault to the output MOSFET
being shut off. This delay is due to thermal time
constants within the system itself. In no event will the
device be damaged due to thermal overload because
die temperature is monitored continuously by on-chip
circuitry.
Micrel
MIC2005/MIC2015
August 2005
13
M9999-080305
(408) 955-1690
Application Information
I
LIMIT
vs. I
OUT
measured
The MIC2005/2015's current limiting circuitry is
designed to act as a constant current source to the load.
As the load tries to pull more than the allotted current,
V
OUT
drops and the input to output voltage differential
increases. When V
IN
-V
OUT
exceeds 1V, I
OUT
drops below
I
LIMIT
to reduce the drain of fault current on the system's
power supply and to limit internal heating of the
MIC2005/2015.
When measuring I
OUT
, it is important to bear this voltage
dependence in mind, otherwise, the measurement data
may appear to indicate a problem when none really
exists. This voltage dependence is illustrated in Figures
4 and 5.
In Figure
4, output current is measured as V
OUT
is pulled
below V
IN
, with the test terminating when V
OUT
is 1V
below V
IN
. Observe that once I
LIMIT
is reached, I
OUT
remains constant throughout the remainder of the test.
In Figure
5,
this test is repeated but with V
IN
- V
OUT
exceeding 1V.
When V
IN
- V
OUT
> 1V, the MIC2005/2015's current
limiting circuitry responds by decreasing I
OUT
, as can be
seen in Figure 5. In this demonstration, V
OUT
is being
controlled and I
OUT
is the measured quantity. In real life
applications, V
OUT
is determined in accordance with
Ohm's law by the load and the limiting current.
Figure 4. I
OUT
in Current Limiting for V
IN
- V
OUT
1V
Figure 5. I
OUT
in Current Limiting for V
IN
- V
OUT
>1V
This folding back of I
LIMIT
can be generalized by plotting
I
LIMIT
as a function of V
OUT
, as shown below. The slope
of V
OUT
between I
OUT
= 0 and I
OUT
= I
LIMIT
(where I
LIMIT
=
1) is determined by R
ON
of MIC2005/2015 and I
LIMIT
.
0
0.2
0.4
0.6
0.8
1.0
1.2
0
1
2
3
4
5
6
NORMALIZED OU
TPUT CUR
RENT (A)
OUTPUT VOLTAGE (V)
Normalized Output Current
vs. Output Voltage (5V)
Figure 6.
Micrel
MIC2005/MIC2015
August 2005
14
M9999-080305
(408) 955-1690
0
0.2
0.4
0.6
0.8
1.0
1.2
0
0.5 1.0 1.5 2.0 2.5 3.0
NORMALIZED
OUTPU
T
C
URREN
T
(A)
OUTPUT VOLTAGE (V)
Normalized Output Current
vs. Output Voltage (2.5V)
Figure 7.
C
SLEW
The CSLEW input is provided to increase control of the
output voltage ramp at turn-on. This input allows
designers the option of decreasing the output's slew rate
(slowing the voltage rise) by adding an external
capacitance between the pin, CSLEW, and VIN. This
capacitance slows the rate at which the pass FET gate
voltage increases and thus, slows both the response to
an Enable command as well as V
OUT
's ascent to its final
value.
Figure 8 illustrates effect of C
SLEW
on turn-ON delay and
output rise time.
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0 0 0 0 0 0 0 0 0 0
TIME
(mS)
C
SLEW
(nF)
Typical Turn-on Times
vs. External C
SLEW
Capacitance
2
4
6
8
10
12
14
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
T
RISE
T
DELAY
T
ON
Figure 8.
C
SLEW
's effect on I
LIMIT
An unavoidable consequence of adding C
capacitance is a reduction in the MIC2005/2015's ability
to quickly limit current transients or surges. A
sufficiently large capacitance can prevent both the
primary and secondary current limits from acting in time
to prevent damage to the MIC2005/2015 or the system
from a short circuit fault. For this reason, the upper limi
SLEW
t
on the value of C
SLEW
is 4nF.
Kickstart (MIC2015)
Kickstart allows brief current surges to pass to the load
before the onset of normal current limiting, which
permits dynamic loads to draw bursts of energy without
sacrificing system safety.
Functionally, Kickstart is a forced override of the normal
current limiting function provided by the MIC2015. The
Kickstart period is governed by an internal timer which
allows current to pass unimpeded to the load for 128ms
and then normal (primary) current limiting goes into
action.
During Kickstart, a secondary current limiting circuit
monitors output current to prevent damage to the
MIC2015, as a hard short combined with a robust power
supply can result in currents of many tens of amperes.
This secondary current limit is nominally set at 4 Amps
and reacts immediately and independently of the
Kickstart period. Once the Kickstart timer has finished its
count, the primary current limiting circuit takes over and
holds I
OUT
to its programmed limit for as long as the
excessive load persists.
Once the MIC2015 drops out of current limiting, the
Kickstart timer initiates a lock-out period of 128ms such
that no further bursts of current, above the primary
current limit, will be allowed until the lock-out period has
expired.
Kickstart may be over-ridden by the thermal protection
circuit and if sufficient internal heating occurs, Kickstart
will be terminated and I
OUT
0. Upon cooling, if the
load is still present I
OUT
I
LIMIT
, not I
KICKSTART
.
FAULT/
ENABLE
V
OUT
I
OUT
0
Time (ms )
100
200
300
400
500
600
Kickstart
Current Limiting
Load Removed
Micrel
MIC2005/MIC2015
August 2005
15
M9999-080305
(408) 955-1690
Figure 9. Kickstart
Supply Filtering
A 0.1F to 1F bypass capacitor positioned close to the
V
IN
and GND pins of the MIC2005/2015 is both good
design practice and required for proper operation of the
MIC2005/2015. This will control supply transients and
ringing. Without a bypass capacitor, large current surges
or an output short may cause sufficient ringing on V
IN
(from supply lead inductance) to cause erratic operation
of the MIC2005/2015's control circuitry. Good quality,
low ESR capacitors, such as Panasonic's TE or ECJ
series, are suggested.
When bypassing with capacitors of 10F and up, it is
good practice to place a smaller value capacitor in
parallel with the larger to handle the high frequency
components of any line transients. Values in the range
of 0.01F to 0.1F are recommended. Again, good
quality, low ESR capacitors should be chosen.
Power Dissipation
Power dissipation depends upon several factors such as
the load, PCB layout, ambient temperature, and supply
voltage. Calculation of power dissipation can be
accomplished by the following equation:
(
)
2
OUT
DS(ON)
D
I
R
P
=
To relate this to junction temperature, the following
equation can be used:
A
A)
-
(J
D
J
T
R
P
T
+
=
Where: T
J
= junction temperature,
T
A
= ambient temperature
R
(J-A)
is the thermal resistance of the package
In normal operation, the MIC2005/2015's Ron is low
enough that no significant I
2
R heating occurs. Device
heating is most often caused by a short circuit, or very
heavy load, when a significant portion of the input
supply voltage appears across the MIC2005/2015's
power MOSFET. Under these conditions the heat
generated will exceed the package and PCB's ability to
cool the device and thermal limiting will be invoked.
In Figure 10, die temperature is plotted against I
OUT
assuming a constant case temperature of 85C. The
plots also assume a worst case R
ON
of 140 m at a die
temperature of 135C. Under these conditions, it is clear
that an SOT-23 packaged device will be on the verge of
thermal shutdown, typically 145C die temperature,
when operating at a load current of 1.25A. For this
reason, it is recommend that MLF package be used for
any MIC2005/2015 designs intending to supply
continuous currents of 1A or more.
Die Temperature vs. Iout for Tcase = 85C
0
20
40
60
80
100
120
140
160
0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
Iout - Amps
D
i
e T
e
m
p
er
at
u
r
e -
C
SOT-23
MLF
Figure 10.
Figure 10 assumes no backside contact is made to the
thermal pad provided on the MLF package. For optimal
performance at higher current levels, or in higher
temperature environments, thermal contact with the
PCB and the exposed power paddle on the back side of
the MLF package should be made. This significantly
reduces the package's thermal resistance thereby
extending the MIC2005/2015's operating range. It
should be noted that this backside paddle is electrically
active and is connected to the MIC2005/2015's GND
pin.
2 Vias
0.3 mm diam.
to Ground Plane
0.8 mm
1.4 mm
Figure 11. Pad for thermal mounting to PCB
Micrel
MIC2005/MIC2015
August 2005
16
M9999-080305
(408) 955-1690
Package Information
6-Pin SOT-23 (M6)
6 Pin 2mmX2mm MLF (ML)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for
its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a
product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for
surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant
injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk
and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale.
2005 Micrel, Incorporated.
Micrel
MIC2005/MIC2015
August 2005
17
M9999-080305
(408) 955-1690
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