Datasheet MIC5013 Datasheet (MICREL)

MIC5013 Micrel

MIC5013

Protected High- or Low-Side MOSFET Driver

General Description

The MIC5013 is an 8-pin MOSFET driver with over-current
shutdown and a fault flag. It is designed to drive the gate of
an N-channel power MOSFET above the supply rail high-side
power switch applications. The MIC5013 is compatible with
standard or current-sensing power MOSFETs in both high­and low-side driver topologies.

The MIC5013 charges a 1nF load in 60µs typical and protects
the MOSFET from over-current conditions. The current sense
trip point is fully programmable and a dynamic threshold
allows high in-rush current loads to be started. A fault pin
indicates when the MIC5013 has turned off the FET due to
excessive current.

Other members of the Micrel driver family include the MIC5011
minimum parts count driver and MIC5012 dual driver.

Typical Application

Features

• 7V to 32V operation

• Less than 1µA standby current in the “OFF” state

• Available in small outline SOIC packages

• Internal charge pump to drive the gate of an N-channel

power FET above supply

• Internal zener clamp for gate protection

• 60µs typical turn-on time to 50% gate overdrive

• Programmable over-current sensing

• Dynamic current threshold for high in-rush loads

• Fault output pin indicates current faults

• Implements high- or low-side switches

Applications

• Lamp drivers

• Relay and solenoid drivers

• Heater switching

• Power bus switching

• Motion control

Ordering Information

Control Input

Note: The MIC5013 is ESD sensitive.

R

TH

20kΩ

1
2
3
4

MIC5013

Input
Thresh
Sense
Source

Part Number Temperature Range Package

MIC5013BN –40°C to +85°C 8-pin Plastic DIP
MIC5013BM –40°C to +85°C 8-pin SOIC

+

=24V

V

+

10µF

8

Fault

7

V+

6

Gate

5

Gnd

SENSE

43Ω

KELVIN

R

S

R1

4.3kΩ

IRCZ44
(S=2590,
R=11mΩ)

SOURCE

LOAD

Figure 1. High-Side Driver with

Current-Sensing MOSFET

SR( +100mV)

V

R I

– ( +100mV)

L

V

100mV

2200

V

TRIP

=30A (trip current)I

=100mV

TRIP

V

TRIP

+

SRR

(SR+R )

S

S

R =

S

R1=

R = –1000

TH

For this example:

L

V

TRIP

Protected under one or more of the following Micrel patents:

patent #4,951,101; patent #4,914,546

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

July 2000 1 MIC5013

MIC5013 Micrel

Absolute Maximum Ratings (Note 1, 2)

Input Voltage, Pin 1 –10 to V
Threshold Voltage, Pin 2 –0.5 to +5V
Sense Voltage, Pin 3 –10V to V
Source Voltage, Pin 4 –10V to V
Current into Pin 4 50mA
Gate Voltage, Pin 6 –1V to 50V
Supply Voltage (V+), Pin 7 –0.5V to 36V
Fault Output Current, Pin 8 –1mA to +1mA
Junction Temperature 150°C

Pin Description (Refer to Figures 1 and 2)

Pin Number Pin Name Pin Function

1 Input Resets current sense latch and turns on power MOSFET when taken above

threshold (3.5V typical). Pin 1 requires <1µA to switch.

2 Threshold Sets current sense trip voltage according to:

where RTH to ground is 3.3k to 20kΩ. Adding capacitor CTH increases the
trip voltage at turn-on to 2V. Use C
constant.

3 Sense The sense pin causes the current sense to trip when V

V

SOURCE

a 3 lead FET or a resistor RS in the sense lead of a current sensing FET.

4 Source Reference for the current sense voltage on pin 3 and return for the gate

clamp zener. Connect to the load side of current shunt or kelvin lead of
current sensing FET. Pins 3 and 4 can safely swing to –10V when turning

off inductive loads.
5 Ground
6 Gate Drives and clamps the gate of the power FET. Pin 6 will be clamped to

approximately –0.7V by an internal diode when turning off inductive loads.
7V

8 Fault Outputs status of protection circuit when pin 1 is high. Fault low indicates

+

Supply pin; must be decoupled to isolate from large transients caused by

the power FET drain. 10µF is recommended close to pins 7 and 5.

normal operation; fault high indicates current sense tripped.

Operating Ratings (Notes 1, 2)

+

Power Dissipation 1.25W

θ

(Plastic DIP) 100°C/W

JA

+

θJA (SOIC) 170°C/W

+

Ambient Temperature: B version –40°C to +85°C
Storage Temperature –65°C to +150°C
Lead Temperature 260°C
(Soldering, 10 seconds)
Supply Voltage (V+), Pin 7 7V to 32V high side

7V to 15V low side

V=

TRIP

=10µF for a 10ms turn-on time

TH

. Pin 3 is used in conjunction with a current shunt in the source of

2200

R +1000

TH

SENSE

is V

TRIP

above

Pin Configuration

MIC5013

1

Input

2

Thresh

3

Sense

4

Source

MIC5013 2 July 2000

Fault

V+

Gate

Gnd

8
7
6
5

MIC5013 Micrel

Electrical Characteristics (Note 3) Test circuit. T

= –55°C to +125°C, V+ = 15V, all switches open, unless

A

otherwise specified.

Parameter Conditions Min Typical Max Units

Supply Current, I

Logic Input Voltage, V

Logic Input Current, I

7

IN

1

Input Capacitance Pin 1 5 pF
Gate Drive, V

GATE

Zener Clamp, S2 closed, VIN = 5V V+ = 15V, VS = 15V 11 12.5 15 V
V

– V

GATE

Gate Turn-on Time, t

SOURCE

ON

(Note 4) for V
Gate Turn-off Time, t

OFF

Threshold Bias Voltage, V
Current Sense Trip Voltage, S2 closed, VIN = 5V, V+ = 7V, S4 closed 75 105 135 mV
V

– V

SENSE

SOURCE

Peak Current Trip Voltage, S3, S4 closed, 1.6 2.1 V
V

– V

SENSE

Fault Output Voltage, V

SOURCE

8

V+ = 32V VIN = 0V, S4 closed 0.1 10 µA

VIN = VS = 32V 8 20 mA

V+ = 4.75V Adjust VIN for V

Adjust VIN for V

V+ =15V Adjust VIN for V

low 2 V

GATE

high 4.5 V

GATE

high 5.0 V

GATE

V+ = 32V VIN = 0V –1 µA

VIN = 32V 1 µA

S1, S2 closed, V+ = 7V, I6 = 0 13 15 V
VS = V+, VIN = 5V V+ = 15V, I6 = 100 µA2427V

V+ = 32V, VS = 32V 11 13 16 V

VIN switched from 0 to 5V; measure time 60 200 µs

to reach 20V

GATE

VIN switched from 5 to 0V; measure time 4 10 µs
for V

I2 = 200 µA 1.7 2 2.2 V

2

Increase I

to reach 1V

GATE

3

I2 = 100 µAVS = 4.9V, S4 open 70 100 130 mV
V+ = 15V S4 closed 150 210 270 mV
I2 = 200 µAVS = 11.8V, S4 open 140 200 260 mV
V+ = 32V VS = 0V, S4 open 360 520 680 mV
I2 = 500 µAVS = 25.5V, S4 open 350 500 650 mV

V+ = 15V, VIN = 5V
VIN = 0V, I8 = –100 µA 0.4 1 V
VIN = 5V, I8 = 100 µA, current sense tripped 14 14.6 V

Note 1 Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when

Note 2 The MIC5010 is ESD sensitive.
Note 3 Minimum and maximum Electrical Characteristics are 100% tested at TA = 25°C and TA = 85°C, and 100% guaranteed over the entire

Note 4 Test conditions reflect worst case high-side driver performance. Low-side and bootstrapped topologies are significantly faster—see

operating the device beyond its specified Operating Ratings.

range. Typicals are characterized at 25°C and represent the most likely parametric norm.

Applications Information.

July 2000 3 MIC5013

MIC5013 Micrel

Test Circuit

V

IN

S3

Typical Characteristics

Supply Current

12

10

8

6

4

2

SUPPLY CURRENT (mA)

V+

I3

50Ω

500Ω

I2

S4

1W

S2

VS

1
2
3
4

3.5k

MIC5013

Input
Thresh
Sense
Source

Fault

V+

Gate

Gnd

8
7
6
5

V

+

1µF

GATE

1nF

I8

S1

I6

DC Gate Voltage
above Supply

14
12
10

8
6

VGATE – V+ (V)

4
2

0

0 5 10 15 20 25 30 35

SUPPLY VOLTAGE (V)

High-side Turn-on Time*

350
300

250
200

150
100

TURN-ON TIME (µS)

50

0

03691215

SUPPLY VOLTAGE (V)

* Time for gate to reach V+ + 5V in test circuit with VS = V+ – 5V (prevents gate clamp from interfering with measurement).

C =1 nF

GATE

0

0 3 6 9 12 15

SUPPLY VOLTAGE (V)

High-side Turn-on Time*

3.5

3.0
C =10 nF

2.5

2.0

1.5

1.0

TURN-ON TIME (mS)

0.5

0

03691215

SUPPLY VOLTAGE (V)

GATE

MIC5013 4 July 2000

MIC5013 Micrel

TURN-ON TIME (µS)

Typical Characteristics (Continued)

Low-side Turn-on Time
for Gate = 5V

1000

300

100

30
10

C =1 nF

GATE

TURN-ON TIME (µS)

3

1

03691215

C =10 nF

GATE

SUPPLY VOLTAGE (V)

Turn-off Time

50

Low-side Turn-on Time
for Gate = 10V

3000

C =10 nF

1000

300

100

C =1 nF

30

10

3

GATE

03691215

GATE

SUPPLY VOLTAGE (V)

Turn-on Time

2.0

C =10 nF

40

30

20

TURN-OFF TIME (µS)

10

0

03691215

GATE

C =1 nF

GATE

SUPPLY VOLTAGE (V)

250

200

150

100

Charge Pump
Output Current

V =V

GATE

+

V =V +5V

GATE

1.75

1.5

1.25

1.0

0.75

NORMALIZED TURN-ON TIME

0.5
–25 0 25 50 75 100 125

DIE TEMPERATURE (°C)

+

July 2000 5 MIC5013

50

+

VS=V –5V

CHARGE-PUMP CURRENT (µA)

0

0 5 10 15 20 25 30

SUPPLY VOLTAGE (V)

MIC5013 Micrel

Block Diagram

V+

7

1

Input

Fault

8

LOGIC

CURRENT

SENSE
LATCH

R

Q

S

V. REG

52

Ground Threshold

MIC5013

Applications Information

Functional Description (refer to block diagram)

The various MIC5013 functions are controlled via a logic
block connected to the input pin 1. When the input is low, all
functions are turned off for low standby current and the gate
of the power MOSFET is also held low through 500Ω to an
N-channel switch. When the input is taken above the turn­on threshold (3.5V typical), the N-channel switch turns off
and the charge pump is turned on to charge the gate of the
power FET. A bandgap type voltage regulator is also turned
on which biases the current sense circuitry.

The charge pump incorporates a 100kHz oscillator and on­chip pump capacitors capable of charging 1nF to 5V above
supply in 60µs typical. The charge pump is capable of
pumping the gate up to over twice the supply voltage. For
this reason, a zener clamp (12.5V typical) is provided
between the gate pin 6 and source pin 4 to prevent exceed­ing the VGS rating of the MOSFET at high supplies.

The current sense operates by comparing the sense volt­age at pin 3 to an offset version of the source voltage at pin

4. Current I2 flowing in threshold pin 2 is mirrored and
returned to the source via a 1kΩ resistor to set the offset, or
trip voltage. When (V
current sense trips and sets the current sense latch to turn
off the power FET. An integrating comparator is used to
reduce sensitivity to spikes on pin 3. The latch is reset to turn
the FET back on by “recycling” the input pin 1 low and then
high again.

A resistor RTH from pin 2 to ground sets I2, and hence V
An additional capacitor CTH from pin 2 to ground creates a
higher trip voltage at turn-on, which is necessary to prevent
high in-rush current loads such as lamps or capacitors from
false-tripping the current sense.

SENSE

– V

SOURCE

) exceeds V

TRIP

, the

TRIP

CHARGE

PUMP

500Ω

V+

+

I2

–

1k

V

TRIP

+

1k

–

6

12.5V

3

4

Gate

Sense

Source

When the current sense has tripped, the fault pin 8 will be
high as long as the input pin 1 remains high. However, when
the input is low the fault pin will also be low.

Construction Hints

High current pulse circuits demand equipment and assem­bly techniques that are more stringent than normal low
current lab practices. The following are the sources of
pitfalls most often encountered during prototyping: Sup­plies: many bench power supplies have poor transient
response. Circuits that are being pulse tested, or those that
operate by pulse-width modulation will produce strange
results when used with a supply that has poor ripple
rejection, or a peaked transient response. Monitor the
power supply voltage that appears at the drain of a high­side driver (or the supply side of the load in a low-side driver)
with an oscilloscope. It is not uncommon to find bench
power supplies in the 1kW class that overshoot or under­shoot by as much as 50% when pulse loaded. Not only will
the load current and voltage measurements be affected, but
it is possible to over-stress various components—espe-
cially electrolytic capacitors—with possibly catastrophic
results. A 10µF supply bypass capacitor at the chip is
recommended.

Residual Resistances:

Resistances in circuit connections
may also cause confusing results. For example, a circuit
may employ a 50mΩ power MOSFET for low drop, but
careless construction techniques could easily add 50 to
100mΩ resistance. Do not use a socket for the MOSFET. If
the MOSFET is a TO-220 type package, make high-current

.

drain connections to the tab. Wiring losses have a profound
effect on high-current circuits. A floating millivoltmeter can
identify connections that are contributing excess drop un­der load.

MIC5013 6 July 2000

MIC5013 Micrel

Applications Information (Continued)

V

MIC5013

Control Input

R

TH

10kΩ

1

Input

2

Thresh

3

Sense

4

Source

Figure 2. Low-Side Driver with

Circuit Topologies

The MIC5013 is suited for use in high- or low-side driver
applications with over-current protection for both current­sensing and standard MOSFETs. In addition, the MIC5013
works well in applications where, for faster switching times,
the supply is bootstrapped from the MOSFET source out­put. Low voltage, high-side drivers (such as shown in the
Test Circuit) are the slowest; their speed is reflected in the
gate turn-on time specifications. The fastest drivers are the
low-side and bootstrapped high-side types. Load current
switching times are often much faster than the time to full
gate enhancement, depending on the circuit type, the
MOSFET, and the load. Turn-off times are essentially the
same for all circuits (less than 10µs to V

= 1V). The choice

GS

of one topology over another is based on a combination of
considerations including speed, voltage, and desired sys­tem characteristics. Each topology is described in this
section. Note that IL, as used in the design equations, is the
load current that just trips the over-current comparator.

Low-Side Driver with Current Shunt (Figure 2). The over-

MIC5013

Control Input

R

TH

20kΩ

1
2

Thresh

3
4

Source

Input

Sense

Fault

Gate

8

Fault

7

V+

6

Gate

5

Gnd

Current Shunt

10µF

8
7

V+

6
5

Gnd

R1

24kΩ

V

LOAD

+

=7 to 15V

10µF

+

LOAD

IRF540

R

S

10mΩ
IRC 4LPW-5

(International Resistive Company)

V

TRIP

R =

S

I

L

2200

R =

TH

For this example:
I =20A (trip current)

L

V

TRIP

–1000

V

TRIP

= 200mV

current comparator monitors RS and trips if IL × RS exceeds
V

. R is selected to produce the desired trip voltage.

TRIP

As a guideline, keep V

within the limits of 100mV and

TRIP

500mV (RTH = 3.3kΩ to 20kΩ). Thresholds at the high end
offer the best noise immunity, but also compromise switch
drop (especially in low voltage applications) and power
dissipation.

The trip current is set higher than the maximum expected
load current—typically twice that value. Trip point accuracy
is a function of resistor tolerances, comparator offset (only
a few millivolts), and threshold bias voltage (V2). The values
shown in Figure 2 are designed for a trip current of 20
amperes. It is important to ground pin 4 at the current shunt
RS, to eliminate the effects of ground resistance.

A key advantage of the low-side topology is that the load
supply is limited only by the MOSFET BVDSS rating.
Clamping may be required to protect the MOSFET drain
terminal from inductive switching transients. The MIC5013

+

=24V

100Ω

R2

V

+

IRF541

LOAD

R

S

18mΩ
IRC 4LPW-5*

R1=

R2=100Ω

R =

R =

For this example:
I =10A (trip current)

V =100mV

*International Resistive Company

S

TH

L

TRIP

+

V

1mA

100mV+

I
2200
V

TRIP

V

TRIP

L

–1000

Figure 3. High-Side Driver

with Current Shunt

July 2000 7 MIC5013

MIC5013 Micrel

Applications Information (Continued)

V

LOAD

MIC5013

Control Input

R

TH

20kΩ

1
2

Thresh

3
4

Source

Input

Sense

Fault

V+

Gate

Gnd

8
7
6
5

Figure 4. Low-Side Driver with

Current-Sensing MOSFET

supply should be limited to 15V in low-side topologies;
otherwise, a large current will be forced through the gate
clamp zener.

Low-side drivers constructed with the MIC501X family are
also fast; the MOSFET gate is driven to near supply
immediately when commanded ON. Typical circuits achieve
10V enhancement in 10µs or less on a 12 to 15V supply.

High-Side Driver with Current Shunt (Figure 3). The
comparator input pins (source and sense) float with the
current sensing resistor (R
add a small, additional potential to V

) on top of the load. R1 and R2

S

to prevent false-

TRIP

triggering of the over-current shutdown circuit with open or
inductive loads. R1 is sized for a current flow of 1mA, while
R2 contributes a drop of 100mV. The shunt voltage should
be 200 to 500mV at the trip point. The example of Figure 3
gives a 10A trip current when the output is near supply. The
trip point is somewhat reduced when the output is at ground
as the voltage drop across R1 (and therefore R2) is zero.

High-side drivers implemented with MIC5013 drivers are
self-protected against inductive switching transients. Dur­ing turn-off an inductive load will force the MOSFET source
5V or more below ground, while the driver holds the gate at
ground potential. The MOSFET is forced into conduction,
and it dissipates the energy stored in the load inductance.
The MIC5013 source and sense pins (3 and 4) are designed
to withstand this negative excursion without damage. Exter­nal clamp diodes are unnecessary.

Current Shunts (RS). Low-valued resistors are necessary
for use at RS.Values for RS range from 5 to 50mΩ, at 2 to
10W. Worthy of special mention are Kelvin-sensed, “four-
terminal” units supplied by a number of manufacturers
(see next page). Kelvin-sensed resistors eliminate errors

+

V

SENSE

=15V

10µF

+

R

S

22Ω

KELVIN

LOAD

IRCZ44
(S=2590,
R=11mΩ)

SOURCE

SR

V

R I

–

V

L

2200
V

TRIP

=100mV

TRIP

TRIP

R =

S

R = –1000

TH

For this example:
I

=20A (trip current)

L

V

TRIP

caused by lead and terminal resistances, and simplify
product assembly. 10% tolerance is normally adequate,
and with shunt potentials of 200mV thermocouple effects
are insignificant. Temperature coefficient is important; a
linear, 500 ppm/°C change will contribute as much as 10%
shift in the over-current trip point. Most power resistors
designed for current shunt service drift less than 100 ppm/
°C.

Low-Side Driver with Current Sensing MOSFET (Figure

4). Several manufacturers now supply power MOSFETs in
which a small sampling of the total load current is diverted
to a “sense” pin. One additional pin, called “Kelvin source,”
is included to eliminate the effects of resistance in the
source bond wires. Current-sensing MOSFETs are speci­fied with a sensing ratio “S” which describes the relationship
between the on-resistance of the sense connection and the
body resistance “R” of the main source pin. Current sensing
MOSFETs eliminate the current shunt required by standard
MOSFETs.

The design equations for a low-side driver using a current
sensing MOSFET are shown in Figure 4. “S” is specified on
the MOSFET’s datasheet, and “R” must be measured or
estimated. V

must be less than R × IL, or else RS will

TRIP

become negative. Substituting a MOSFET with higher on­resistance, or reducing V

fixes this problem. V

TRIP

100 to 200mV is suggested. Although the load supply is
limited only by MOSFET ratings, the MIC5013 supply
should be limited to 15V to prevent damage to the gate
clamp zener. Output clamping is necessary for inductive
loads.

†

“R” is the body resistance of the MOSFET, excluding bond

resistances. R

as specified on MOSFET data sheets

DS(ON)

TRIP

=

† Suppliers of Kelvin-sensed power resistors:

Dale Electronics, Inc., 2064 12th Ave., Columbus, NE 68601. Tel: [phone]
International Resistive Co., P.O. Box 1860, Boone, NC 28607-1860. Tel: [phone]
Kelvin, 14724 Ventura Blvd., Ste. 1003, Sherman Oaks, CA 91403-3501. Tel: [phone]
RCD Components, Inc., 520 E. Industrial Pk. Dr., Manchester, NH 03103. Tel: [phone]
Ultronix, Inc., P.O. Box 1090, Grand Junction, CO 81502. Tel: [phone]

MIC5013 8 July 2000

MIC5013 Micrel

Applications Information (Continued)

12V

+

V+

8
7
6
5

10µF

R1

3.9kΩ

43Ω

DS(ON)

DS(ON)

IRCZ44

#6014

, or

for

MIC5013

Control Input

R

TH2

1kΩ

C

TH

22µF

R

TH1

22kΩ

1
2
3
4

Input
Thresh
Sense
Source

Fault

Gate

Gnd

Figure 5. Time-Variable

Trip Threshold

includes bond resistances. A Kelvin-connected ohmmeter
(using TAB and SOURCE for forcing, and SENSE and
KELVIN for sensing) is the best method of evaluating “R.”
Alternatively, “R” can be estimated for large MOSFETs
(R

≤ 100mΩ) by simply halving the stated R

DS(ON)

by subtracting 20 to 50mΩ from the stated R
smaller MOSFETs.

High-Side Driver with Current Sensing MOSFET (Figure

5). The design starts by determining the value of “S” and “R”
for the MOSFET (use the guidelines described for the low­side version). Let V

= 100mV, and calculate RS for a

TRIP

desired trip current. Next calculate RTH and R1. The trip
point is somewhat reduced when the output is at ground as
the voltage drop across R1 is zero. No clamping is required
for inductive loads, but may be added to reduce power
dissipation in the MOSFET.

Typical Applications

Start-up into a Dead Short. If the MIC5013 attempts to turn
on a MOSFET when the load is shorted, a very high current
flows. The over-current shutdown will protect the MOSFET,
but only after a time delay of 5 to 10µs. The MOSFET must
be capable of handling the overload; consult the device’s
SOA curve. If a short circuit causes the MOSFET to exceed
its 10µs SOA, a small inductance in series with the source
can help limit di/dt to control the peak current during the 5
to 10µs delay.

When testing short-circuit behavior, use a current probe
rated for both the peak current and the high di/dt.

The over-current shutdown delay varies with comparator
overdrive, owing to noise filtering in the comparator. A delay
of up to 100µs can be observed at the threshold of shut­down. A 20% overdrive reduces the delay to near minimum.

Incandescent Lamps. The cold filament of an incandes­cent lamp exhibits less than one-tenth as much resistance
as when the filament is hot. The initial turn-on current of a
#6014 lamp is about 70A, tapering to 4.4A after a few

7 to 15V

1N5817

Control Input

R

TH

20kΩ

1

Input

2

Thresh

3

Sense

4

Source

MIC5013

Fault

Gate

Gnd

V+

8
7

100nF

6
5

+

V

R1=

1mA

+

10µF

100Ω

R2

1N4001 (2)

IRF540

LOAD

R

S

18mΩ

Figure 6. Bootstrapped

High-Side Driver

hundred milliseconds. It is unwise to set the over-current trip
point to 70A to accommodate such a load. A “resistive” short
that draws less than 70A could destroy the MOSFET by
allowing sustained, excessive dissipation. If the over-cur­rent trip point is set to less than 70A, the MIC5013 will not
start a cold filament. The solution is to start the lamp with a
high trip point, but reduce this to a reasonable value after the
lamp is hot.

The MIC5013 over-current shutdown circuit is designed to
handle this situation by varying the trip point with time (see
Figure 5). R

functions in the conventional manner,

TH1

providing a current limit of approximately twice that required
by the lamp. R

acts to increase the current limit at turn-

TH2

on to approximately 10 times the steady-state lamp current.
The high initial trip point decays away according to a 20ms
time constant contributed by CTH. R

could be eliminated

TH2

with CTH working against the internal 1kΩ resistor, but this
results in a very high over-current threshold. As a rule of
thumb design the over-current circuitry in the conventional
manner, then add the R
start-up. Let R

TH2

= (R

TH1

TH2/CTH

network to allow for lamp

÷10)–1kΩ, and choose a capaci­tor that provides the desired time constant working against
R

and the internal 1kΩ resistor.

TH2

When the MIC5013 is turned off, the threshold pin (2)
appears as an open circuit, and CTH is discharged through
R

TH1

and R

. This is much slower than the turn-on time

TH2

constant, and it simulates the thermal response of the
filament. If the lamp is pulse-width modulated, the current
limit will be reduced by the residual charge left in CTH.

Modifying Switching Times. Do not add external capaci­tors to the gate to slow down the switching time. Add a
resistor (1kΩ to 51kΩ) in series with the gate of the MOS­FET to achieve this result.

Bootstrapped High-Side Driver (Figure 6). The speed of
a high-side driver can be increased to better than 10µs by
bootstrapping the supply off of the MOSFET source. This
topology can be used where the load is pulse-width modu-

July 2000 9 MIC5013

MIC5013 Micrel

Fault

V+

Gate

1
2
3
4

8

MIC5013

Gnd

7
6
5

Thresh
Sense
Source

Input

IRFZ40

10µF

20kΩ

Figure 7. 10-Ampere

Electronic Circuit Breaker

+

100Ω

22mΩ

LOAD

12V

10kΩ

10kΩ

100nF

1N4148

100kΩ100kΩ100kΩ

MPSA05

CPSL-3 (Dale)

Applications Information (Continued)

15V

10mA
Control Input

33pF

100kΩ

4N35

100kΩ

1kΩ

33kΩ

To MIC5013 Input

MPSA05

Figure 8. Improved

Opto-Isolator Performance

24V

100kΩ

OFF

ON

CR2943-NA102A
(GE)

330kΩ

20kΩ

1
2
3
4

lated (100Hz to 20kHz), or where it is energized for only a
short period of time (≤25ms). If the load is left energized for
a long period of time (>25ms), the bootstrap capacitor will
discharge and the MIC5013 supply pin will fall to V+ = V
–1.4. Under this condition pins 3 and 4 will be held above V+
and may false trigger the over-current circuit. A larger
capacitor will lengthen the maximum “on” time; 1000µF will
hold the circuit up for 2.5 seconds, but requires more charge
time when the circuit is turned off. The optional Schottky
barrier diode improves turn-on time on supplies of less than
10V.

24V

MIC5013

Input
Thresh
Sense
Source

Fault

V+

Gate

Gnd

8
7
6
5

15kΩ

10µF

+

IRFP044 (2)

100Ω

5mΩ

LVF-15 (RCD)

LOAD

DD

Figure 9. 50-Ampere

MIC5013 10 July 2000

Industrial Switch

MIC5013 Micrel

Applications Information (Continued)

Since the supply current in the “OFF” state is only a small
leakage, the 100nF bypass capacitor tends to remain
charged for several seconds after the MIC5013 is turned off.
In a PWM application the chip supply is actually much
higher than the system supply, which improves switching
time.

Electronic Circuit Breaker (Figure 7). The MIC5013 forms
the basis of a high-performance, fast-acting circuit breaker.
By adding feedback from FAULT to INPUT the breaker can
be made to automatically reset. If an over-current condition
occurs, the circuit breaker shuts off. The breaker tests the
load every 18ms until the short is removed, at which time the
circuit latches ON. No reset button is necessary.

Opto-Isolated Interface (Figure 8). Although the MIC5013
has no special input slew rate requirement, the lethargic
transitions provided by an opto-isolator may cause oscilla­tions on the rise and fall of the output. The circuit shown
accelerates the input transitions from a 4N35 opto-isolator
by adding hysteresis. Opto-isolators are used where the
control circuitry cannot share a common ground with the
MIC5013 and high-current power supply, or where the
control circuitry is located remotely. This implementation is
intrinsically safe; if the control line is severed the MIC5013
will turn OFF.

Fault-Protected Industrial Switch (Figure 9). The most
common manual control for industrial loads is a push button
on/off switch. The “on” button is physically arranged in a
recess so that in a panic situation the “off” button, which
extends out from the control box, is more easily pressed.
This circuit is compatible with control boxes such as the
CR2943 series (GE). The circuit is configured so that if both
switches close simultaneously, the “off” button has prece­dence. If there is a fault condition the circuit will latch off, and
it can be reset by pushing the “ON” button.

This application also illustrates how two (or more) MOSFETs
can be paralleled. This reduces the switch drop, and distrib­utes the switch dissipation into multiple packages.

High-Voltage Bootstrap (Figure 10). Although the MIC5013
is limited to operation on 7 to 32V supplies, a floating
bootstrap arrangement can be used to build a high-side
switch that operates on much higher voltages. The MIC5013
and MOSFET are configured as a low-side driver, but the
load is connected in series with ground. The high speed
normally associated with low-side drivers is retained in this
circuit.

Power for the MIC5013 is supplied by a charge pump. A
20kHz square wave (15Vp-p) drives the pump capacitor
and delivers current to a 100µF storage capacitor. A zener
diode limits the supply to 18V. When the MIC5013 is off,
power is supplied by a diode connected to a 15V supply.
The circuit of Figure 8 is put to good use as a barrier
between low voltage control circuitry and the 90V motor
supply.

Half-Bridge Motor Driver (Figure 11). Closed loop control
of motor speed requires a half-bridge driver. This topology
presents an extra challenge since the two output devices
should not cross conduct (shoot-through) when switching.
Cross conduction increases output device power dissipa­tion and, in the case of the MIC5013, could trip the over­current comparator. Speed is also important, since PWM
control requires the outputs to switch in the 2 to 20kHz
range.

The circuit of Figure 11 utilizes fast configurations for both
the top- and bottom-side drivers. Delay networks at each
input provide a 2 to 3µs dead time effectively eliminating
cross conduction. Both the top- and bottom-side drivers are
protected, so the output can be shorted to either rail without
damage.

15V

+

10mA
Control Input

100nF
200V

15Vp-p, 20kHz

Squarewave

1N4003 (2)

100kΩ

4N35

1N4003

33pF

33kΩ

MPSA05

6.2kΩ

100kΩ

1kΩ

Figure 10. High-Voltage

1
2

Thresh

3
4

Source

Input

Sense

MIC5013

Fault

Gate

Gnd

V+

8
7
6
5

100µF

1N4746

1/4 HP, 90V

5BPB56HAA100

(GE)

90V

IRFP250

10mΩ

KC1000-4T
(Kelvin)

M

Bootstrapped Driver

July 2000 11 MIC5013

MIC5013 Micrel

Applications Information (Continued)

The top-side driver is based on the bootstrapped circuit of
Figure 6, and cannot be switched on indefinitely. The
bootstrap capacitor (1µF) relies on being pulled to ground
by the bottom-side output to recharge. This limits the
maximum duty cycle to slightly less than 100%.

Two of these circuits can be connected together to form an
H-bridge. If the H-bridge is used for locked antiphase
control, no special considerations are necessary. In the
case of sign/magnitude control, the “sign” leg of the H­bridge should be held low (PWM input held low) while the
other leg is driven by the magnitude signal.

If current feedback is required for torque control, it is
available in chopped form at the bottom-side driver's 22 mΩ
current-sensing resistor.

Time-Delay Relay (Figure 12). The MIC5013 forms the
basis of a simple time-delay relay. As shown, the delay
commences when power is applied, but the 100 kΩ/1N4148
could be independently driven from an external source such

as a switch or another high-side driver to give a delay
relative to some other event in the system.

Hysteresis has been added to guarantee clean switching at
turn-on. Note that an over-current condition latches the
relay in a safe, OFF condition. Operation is restored by
either cycling power or by momentarily shorting pin 1 to
ground.

Motor Driver with Stall Shutdown (Figure 13). Tachom­eter feedback can be used to shut down a motor driver
circuit when a stall condition occurs. The control switch is a
3-way type; the “START” position is momentary and forces
the driver ON. When released, the switch returns to the
“RUN” position, and the tachometer’s output is used to hold
the MIC5013 input ON. If the motor slows down, the tach
output is reduced, and the MIC5013 switches OFF. Resis­tor “R” sets the shutdown threshold. If the output current
exceeds 30A, the MIC5013 shuts down and remains in that
condition until the momentary “RESET” button is pushed.
Control is then returned to the START/RUN/STOP switch.

15V

100nF

1N5817

PWM

INPUT

1N4148

22kΩ

22kΩ

2N3904

220pF

20kΩ

10kΩ

1nF

1
2
3
4

10kΩ

MIC5013

Input
Thresh
Sense
Source

1
2
3
4

Fault

V+

Gate

Gnd

MIC5013

Input
Thresh
Sense
Source

8
7
6
5

Fault

V+

Gate

Gnd

8
7
6
5

15kΩ

15V

+

1µF

100Ω

+

10µF

1N4001 (2)

IRF541

22mΩ
CPSL-3
(Dale)

M

12V,
10A Stalled

IRF541

22mΩ
CPSL-3
(Dale)

Figure 11. Half-Bridge

Motor Driver

MIC5013 12 July 2000

MIC5013 Micrel

Applications Information (Continued)

12V

+

100kΩ

1N4148

20kΩ

1

Input

2

Thresh

3

Sense

4

Source

MIC5013

Fault

V+

Gate

Gnd

10µF

8
7
6
5

IRCZ44

100µF

100Ω

+

10kΩ

Figure 12. Time-Delay Relay

with 30A Over-Current Protection

1N4148

RESET

1

R

330kΩ

330kΩ

20kΩ

2
3
4

SENSE

MIC5013

Input

Thresh

Sense

Source

330kΩ

Fault

Gate

Gnd

43Ω

4.3kΩ

V+

8
7
6
5

SOURCE

KELVIN

10µF

OUTPUT
(Delay=5s)

12V

+

IRCZ44

SOURCE

SENSE

43Ω

KELVIN

1N4148

100nF

T

12V

START

RUN

STOP

4.3kΩ

M

Figure 13. Motor Stall

Shutdown

July 2000 13 MIC5013

MIC5013 Micrel

Applications Information (Continued)

Gate Control Circuit

When applying the MIC5010, it is helpful to understand the
operation of the gate control circuitry (see Figure 14). The
gate circuitry can be divided into two sections: 1) charge
pump (oscillator, Q1-Q5, and the capacitors) and 2) gate
turn-off switch (Q6).

When the MIC5010 is in the OFF state, the oscillator is
turned off, thereby disabling the charge pump. Q5 is also
turned off, and Q6 is turned on. Q6 holds the gate pin (G) at
ground potential which effectively turns the external MOS­FET off.

Q6 is turned off when the MIC5013 is commanded on. Q5
pulls the gate up to supply (through 2 diodes). Next, the
charge pump begins supplying current to the gate. The gate
accepts charge until the gate-source voltage reaches 12.5V
and is clamped by the zener diode.

A 2-output, three-phase clock switches Q1-Q4, providing a
quasi-tripling action. During the initial phase Q4 and Q2 are
ON. C1 is discharged, and C2 is charged to supply through

Q5. For the second phase Q4 turns off and Q3 turns on,
pushing pin C2 above supply (charge is dumped into the
gate). Q3 also charges C1. On the third phase Q2 turns off
and Q1 turns on, pushing the common point of the two
capacitors above supply. Some of the charge in C1 makes
its way to the gate. The sequence is repeated by turning Q2
and Q4 back on, and Q1 and Q3 off.

In a low-side application operating on a 12 to 15V supply,
the MOSFET is fully enhanced by the action of Q5 alone. On
supplies of more than approximately 14V, current flows
directly from Q5 through the zener diode to ground. To
prevent excessive current flow, the MIC5010 supply should
be limited to 15V in low-side applications.

The action of Q5 makes the MIC5013 operate quickly in
low-side applications. In high-side applications Q5
precharges the MOSFET gate to supply, leaving the charge
pump to carry the gate up to full enhancement 10V above
supply. Bootstrapped high-side drivers are as fast as low­side drivers since the chip supply is boosted well above the
drain at turn-on.

OFF

ON

100 kHz

OSCILLATOR

C1

Q1

Q2

+

V

Q3

125pF125pF

COM

C1 C2

Q4

Figure 14. Gate Control

Circuit Detail

C2

Q5

500Ω

Q6

GATE CLAMP

ZENER

G

12.5V

S

MIC5013 14 July 2000

MIC5013 Micrel

Package Information

PIN 1

DIMENSIONS:

INCH (MM)

0.018 (0.57)

0.100 (2.54)

0.026 (0.65)
MAX)

0.157 (3.99)

0.150 (3.81)

0.050 (1.27)

0.064 (1.63)

0.045 (1.14)

0.380 (9.65)

0.370 (9.40)

TYP

0.197 (5.0)

0.189 (4.8)

0.135 (3.43)

0.125 (3.18)

0.130 (3.30)

0.0375 (0.952)

0.380 (9.65)

0.320 (8.13)

8-Pin Plastic DIP (N)

PIN 1

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)

45°

0.050 (1.27)

0.016 (0.40)

0.244 (6.20)

0.228 (5.79)

0.255 (6.48)

0.245 (6.22)

0.300 (7.62)

0.013 (0.330)

0.010 (0.254)

0.010 (0.25)

0.007 (0.18)

July 2000 15 MIC5013

MIC5013 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.

© 1998 Micrel Incorporated

MIC5013 16 July 2000