Micrel MIC5013 Protected high- or low-side mosfet driver Datasheet

MIC5013
Micrel, Inc.
MIC5013
Protected High- or Low-Side MOSFET Driver
General Description
Features
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
Ordering Information
•
•
•
•
•
•
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
Part Number
+
V =24V
MIC5013
Control Input
10µF
Standard
Pb-Free
MIC5013BN
MIC5013YN
Package
–40ºC to +85ºC
8-pin Plastic
DIP
MIC5013BM MIC5013YM –40ºC to +85ºC
8-pin SOIC
+
Fault 8
2 Thresh
V+ 7
20kΩ 3
Sense Gate 6
RTH
Temperature
Range
1 Input
R =
S
4 Source Gnd 5
SR(V
TR I P
+100mV)
R I L – (V
TR I P
IRCZ44
(S=2590,
R=11mΩ)
SENSE
R
SOURCE
S
43Ω
KEL VIN
R1=
+100mV)
V+S R RS
100mV (SR+ R S)
R TH =
2200
V
–1000
TR I P
LOAD
For this example:
I =30A (trip current)
R1
4.3kΩ
L
V
TR I P
=100mV
Figure 1. High-Side Driver with
Current-Sensing MOSFET
Protected under one or more of the following Micrel patents:
patent #4,951,101; patent #4,914,546
Note: The MIC5013 is ESD sensitive.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
July 2005
1
MIC5013
MIC5013
Micrel, Inc.
Absolute Maximum Ratings (Note 1, 2)
Input Voltage, Pin 1
Threshold Voltage, Pin 2
Sense Voltage, Pin 3
Source Voltage, Pin 4
Current into Pin 4
Gate Voltage, Pin 6
Supply Voltage (V+), Pin 7
Fault Output Current, Pin 8
Junction Temperature
Operating Ratings (Notes 1, 2)
V+
–10 to
–0.5 to +5V
–10V to V+
–10V to V+
50mA
–1V to 50V
–0.5V to 36V
–1mA to +1mA
150°C
Power Dissipation
θJA (Plastic DIP)
θJA (SOIC)
Ambient Temperature: B version
Storage Temperature
Lead Temperature
(Soldering, 10 seconds)
Supply Voltage (V+), Pin 7
1.25W
100°C/W
170°C/W
–40°C to +85°C
–65°C to +150°C
260°C
7V to 32V high side
7V to 15V low side
Pin Description (Refer to Figures 1 and 2)
Pin Number
Pin Name
1
Input
2
Threshold
Pin Function
Resets current sense latch and turns on power MOSFET when taken above
threshold (3.5V typical). Pin 1 requires <1µA to switch.
Sets current sense trip voltage according to:
V
TR I P
=
2200
R TH + 1000
where RTH to ground is 3.3k to 20kΩ. Adding capacitor CTH increases the
trip voltage at turn-on to 2V. Use CTH =10µF for a 10ms turn-on time constant.
3
Sense
4
Source
The sense pin causes the current sense to trip when VSENSE is VTRIP above
VSOURCE. Pin 3 is used in conjunction with a current shunt in the source of
a 3 lead FET or a resistor RS in the sense lead of a current sensing FET.
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.
7
V+
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.
8
Fault
Outputs status of protection circuit when pin 1 is high. Fault low indicates
normal operation; fault high indicates current sense tripped.
Pin Configuration
MIC5013
Fault 8
2
7
Thresh V+
3
Sense Gate 6
4 Source Gnd 5
1
MIC5013
Input
2
July 2005
MIC5013
Micrel, Inc.
Electrical Characteristics (Note 3, 5)
Test circuit. TA = –55°C to +125°C, V+ = 15V, all switches open, unless otherwise specified.
Parameter
Conditions
Supply Current, I7
V+
Logic Input Voltage, VIN
V+ = 4.75V
= 32V
V+ =15V
Logic Input Current, I1
V+ = 32V
Input Capacitance
Pin 1
Gate Drive, VGATE
Zener Clamp,
VGATE – VSOURCE
Gate Turn-on Time, tON
µs
(Note 4)
Gate Turn-off Time, tOFF
Threshold Bias Voltage, V2
Current Sense Trip Voltage,
VSENSE – VSOURCE
Min
VIN = 0V, S4 closed
VIN = VS = 32V
Adjust VIN for VGATE low
Fault Output Voltage, V8
Max
Units
0.1
10
µA
8
20
mA
2
V
Adjust VIN for VGATE high
4.5
5.0
V
VIN = 0V
–1
µA
Adjust VIN for VGATE high
VIN = 32V
V
1
µA
5
pF
S1, S2 closed,
V+
13
15
V
VS = V+, VIN = 5V
V+ = 15V, I6 = 100 µA
24
27
V
11
12.5
15
V
V+ = 32V, VS = 32V
11
13
16
V
60
200
4
10
µs
2
2.2
V
S2 closed, VIN = 5V
= 7V, I6 = 0
V+ = 15V, VS = 15V
VIN switched from 0 to 5V; measure time
for VGATE to reach 20V
VIN switched from 5 to 0V; measure time
for VGATE to reach 1V
I2 = 200 µA
S2 closed, VIN = 5V,
Increase I3
V+
= 7V,
S3, S4 closed,
V+ = 15V, VIN = 5V
1.7
S4 closed
75
105
135
mV
I2 = 100 µA
VS = 4.9V, S4 open
70
100
130
mV
S4 closed
150
210
270
mV
I2 = 200 µA
VS = 11.8V, S4 open
140
200
260
mV
360
520
680
mV
I2 = 500 µA
VS = 25.5V, S4 open
350
500
650
mV
1.6
2.1
14
14.6
V+ = 15V
V+ = 32V
Peak Current Trip Voltage,
VSENSE – VSOURCE
Typical
VIN = 0V, I8 = –100 µA
VS = 0V, S4 open
0.4
VIN = 5V, I8 = 100 µA, current sense tripped
V
1
V
V
Note 1.
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when
operating the device beyond its specified Operating Ratings.
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
range. Typicals are characterized at 25°C and represent the most likely parametric norm.
Note 4.
Test conditions reflect worst case high-side driver performance. Low-side and bootstrapped topologies are significantly faster—see
Applications Information.
Note 5.
Specification for packaged product only.
July 2005
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MIC5013
MIC5013
Micrel, Inc.
Test Circuit
V+
I3
VIN
MIC5013
1 Input
Fault 8
2 Thresh
V+ 7
3 Sense Gate 6
50Ω
500Ω
1W
S 3 I2
+ 1µF
I8
V GATE
4 Source Gnd 5
1nF S 1
3.5k
I6
S4 S2
VS
Typical Characteristics
Supply Current
14
12
10
VGATE – V+ (V)
SUPPLY CURRENT (mA)
12
8
6
4
2
0
DC Gate Voltage
above Supply
10
8
6
4
2
0
5
10
15
20
25
30
0
35
0
3.5
300
3.0
TURN-ON TIME (mS)
TURN-ON TIME (µS)
350
CGATE =1 nF
200
150
100
12
15
CGATE =10 nF
2.5
2.0
1.5
1.0
0.5
50
0
3
6
9
12
0
0
15
* Time for gate to reach
V+
+ 5V in test circuit with VS =
3
6
9
12
15
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
MIC5013
9
High-side Turn-on Time*
High-side Turn-on Time*
0
6
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
250
3
V+
– 5V (prevents gate clamp from interfering with measurement).
4
July 2005
MIC5013
Micrel, Inc.
Typical Characteristics (Continued)
Low-side Turn-on Time
for Gate = 5V
3000
300
CGATE =10 nF
100
30
10
CGATE =1 nF
3
1
0
3
6
9
12
100
CGATE =1 nF
30
10
3
0
3
6
9
12
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
Turn-off Time
Turn-on Time
NORMALIZED TURN-ON TIME
TURN-OFF TIME (µS)
300
15
50
CGATE =10 nF
40
30
20
CGATE =1 nF
10
0
0
CGATE =10 nF
1000
TURN-ON TIME (µS)
TURN-ON TIME (µS)
1000
Low-side Turn-on Time
for Gate = 10V
3
6
9
12
2.0
1.75
1.5
1.25
1.0
0.75
0.5
15
–25
SUPPLY VOLTAGE (V)
CHARGE-PUMP CURRENT (µA)
15
0
25
50
75
100 125
DIE TEMPERATURE (°C)
Charge Pump
Output Current
250
VGATE =V+
200
150
VGATE =V++5V
100
50
VS=V +–5V
0
0
5
10
15
20
25
30
SUPPLY VOLTAGE (V)
July 2005
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MIC5013
MIC5013
Micrel, Inc.
Block Diagram
V+
7
CHARGE
PUMP
6 Gate
500Ω
Input 1
LOGIC
CURRENT
SENSE
LATCH
Fault 8
12.5V
V+
Q
MIC5013
R
S
+
–
3 Sense
I2
+
VTR I P
V. REG
–
1k
4 Source
1k
5
Ground
2
Threshold
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
turn-on 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
on-chip 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 (VSENSE – VSOURCE) exceeds VTRIP,
the 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 VTRIP.
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.
MIC5013
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 high-side 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—especially 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.
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July 2005
MIC5013
Micrel, Inc.
Applications Information (Continued)
VLOAD
V+=7 to 15V
RS=
MIC5013
Control Input
RTH
10kΩ
1 Input
Fault 8
2 Thresh V+ 7
3 Sense Gate 6
10µF
R
+
LOAD
VTR I P
IL
2200
=
TH
VTR I P
–1000
For this example:
4 Source Gnd 5
IRF540
I =20A (trip current)
L
V
TR I P
= 200mV
RS
10mΩ
IRC 4LPW-5
(International Resistive Company)
Figure 2. Low-Side Driver
with Current Shunt
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 VGS = 1V). The choice 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 overcurrent comparator monitors RS and trips if IL × RS exceeds
VTRIP. R is selected to produce the desired trip voltage.
As a guideline, keep VTRIP within the limits of 100mV and
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
V+ =24V
10µF +
MIC5013
Control Input
Fault 8
2 Thresh
V+ 7
20kΩ 3
Sense Gate 6
RTH
V+
R1=
1 Input
1mA
R2=100Ω
RS =
4 Source Gnd 5
IRF541
RTH=
100Ω
R2
R1
24kΩ
RS
18mΩ
IRC 4LPW-5*
LOAD
100mV+ VTR I P
IL
2200
VTR I P
–1000
For this example:
I L =10A (trip current)
VTR I P =100mV
*International Resistive Company
Figure 3. High-Side Driver
with Current Shunt
July 2005
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MIC5013
MIC5013
Micrel, Inc.
Applications Information (Continued)
V LOAD
MIC5013
Control Input
+
V =15V
1 Input
Fault 8
2 Thresh
V+ 7
20kΩ 3
Sense Gate 6
RS =
SR V
TR I P
RI –V
L
10µF
R TH
+
LOAD
R
=
TH
TR I P
2200
V
–1000
TR I P
4 Source Gnd 5
IRCZ44
(S=2590,
R=11mΩ)
SENSE
RS
22Ω
For this example:
I L =20A (trip current)
V
TR I P
=100mV
SOURCE
KEL VIN
Figure 4. Low-Side Driver with
Current-Sensing MOSFET
inductive switching transients. The MIC5013 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 (RS) on top of the load. R1 and R2
add a small, additional potential to VTRIP to prevent falsetriggering 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, “fourterminal” units supplied by a number of manufacturers†
†
(see next page). Kelvin-sensed resistors eliminate errors
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. VTRIP must be less than R × IL, or else RS will
become negative. Substituting a MOSFET with higher onresistance, or reducing VTRIP fixes this problem. VTRIP = 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. RDS(ON) as specified on MOSFET data sheets
includes bond resistances. A Kelvin-connected ohmmeter
Suppliers of Kelvin-sensed power resistors:
Dale Electronics, Inc., 2064 12th Ave., Columbus, NE 68601. Tel: (402) 564-3131
International Resistive Co., P.O. Box 1860, Boone, NC 28607-1860. Tel: (704) 264-8861
Kelvin, 14724 Ventura Blvd., Ste. 1003, Sherman Oaks, CA 91403-3501. Tel: (818) 990-1192
RCD Components, Inc., 520 E. Industrial Pk. Dr., Manchester, NH 03103. Tel: (603) 669-0054
Ultronix, Inc., P.O. Box 1090, Grand Junction, CO 81502. Tel: (303) 242-0810
MIC5013
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July 2005
MIC5013
Micrel, Inc.
Applications Information (Continued)
7 to 15V
1N5817
12V
MIC5013
Control Input
RTH2
1kΩ
CTH
22µF
RTH1
22kΩ
10µF +
Control Input
Fault 8
2 Thresh
V+ 7
3 Sense Gate 6
1 Input
RTH
20kΩ
4 Source Gnd 5
IRCZ4 4
1N4001 (2)
MIC5013
1 Input
2 Thresh
+
Fault 8
V+ 7
3 Sense Gate 6
4 Source Gnd 5
10µF
100nF
IRF540
100Ω
R2
43Ω
R1
3.9kΩ
+
R1= V
1mA
#6014
Figure 5. Time-Variable
Trip Threshold
LOAD
Figure 6. Bootstrapped
High-Side Driver
(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
(RDS(ON) ≤ 100mΩ) by simply halving the stated RDS(ON),
or by subtracting 20 to 50mΩ from the stated RDS(ON) for
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
low-side version). Let VTRIP = 100mV, and calculate RS for
a 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.
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 overcurrent 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). RTH1 functions in the conventional manner, providing a current limit of approximately twice that required by
the lamp. RTH2 acts to increase the current limit at turn-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. RTH2 could be eliminated
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 RTH2/CTH network to allow for lamp
start-up. Let RTH2 = (RTH1÷10)–1kΩ, and choose a capacitor that provides the desired time constant working against
RTH2 and the internal 1kΩ resistor.
When the MIC5013 is turned off, the threshold pin (2) appears as an open circuit, and CTH is discharged through
RTH1 and RTH2. This is much slower than the turn-on time
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
modulated (100Hz to 20kHz), or where it is energized
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
hundred milliseconds. It is unwise to set the over-current
July 2005
RS
18mΩ
9
MIC5013
MIC5013
Micrel, Inc.
Applications Information (Continued)
12V
100kΩ
100kΩ
100nF
100kΩ
MIC5013
10kΩ
+
Fault 8
1 Input
10µF
2 Thresh
V+ 7
20kΩ 3
Sense Gate 6
4 Source Gnd 5
MPSA05
IRFZ40
100Ω
22mΩ
CPSL-3 (Dale)
1N4148
10kΩ
15V
33kΩ
33pF
Figure 7. 10-Ampere
Electronic Circuit Breaker
To MIC5013 Input
100kΩ
MPSA05
10mA
Control Input
LOAD
4N35
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+ = VDD –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.
100kΩ
1kΩ
Figure 8. Improved
Opto-Isolator Performance
24V
24V
100kΩ
CR2943-NA102A
( GE )
ON
OFF
MIC5013
20kΩ
10µF
1 Input
Fault 8
2 Thresh
V+ 7
3 Sense Gate 6
+
4 Source Gnd 5
IRFP044 (2)
100Ω
5mΩ
330kΩ
LVF-15 (RCD)
15kΩ
LOAD
Figure 9. 50-Ampere
Industrial Switch
MIC5013
10
July 2005
MIC5013
Micrel, Inc.
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 over-current
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
+
1N4003 (2)
33kΩ
33pF
100kΩ
10mA
Control Input
MPSA05
4N35
1N4003
MIC5013
1 Input
Fault 8
2 Thresh
V+ 7
3 Sense Gate 6
6.2kΩ
100µF
90V
1N4746
IRFP250
4 Source Gnd 5
100kΩ
10mΩ
KC1000-4T
(Kelvin)
1kΩ
1/4 HP, 90V
5BPB56HAA100 M
( GE )
100nF
200V
15Vp-p, 20kHz
Squarewave
Figure 10. High-Voltage
Bootstrapped Driver
July 2005
11
MIC5013
MIC5013
Micrel, Inc.
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 H-bridge
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
1N5817
100nF
1N4148
22kΩ
1N4001 (2)
MIC5013
1 Input
Fault 8
2 Thresh
V+ 7
3 Sense Gate 6
220pF
20kΩ
+
1µF
4 Source Gnd 5
IRF541
100Ω
22mΩ
CP S L - 3
(Dale)
15kΩ
PWM
INPUT
12V,
M 10A Stalled
15V
MIC5013
10kΩ
22kΩ
1nF
10kΩ
2N3904
1 Input
Fault 8
2 Thresh
V+ 7
3 Sense Gate 6
+
10µF
4 Source Gnd 5
IRF541
22mΩ
CP S L - 3
(Dale)
Figure 11. Half-Bridge
Motor Driver
MIC5013
12
July 2005
MIC5013
Micrel, Inc.
Applications Information (Continued)
12V
100kΩ
1N4148
20kΩ
MIC5013
+
10µF
Fault 8
2 Thresh
V+ 7
3 Sense Gate 6
1 Input
4 Source Gnd 5
100µF
IRCZ44
SOURCE
+
SENSE
10kΩ
KEL VIN
43Ω
100Ω
OUT P UT
(Delay=5s)
4.3kΩ
Figure 12. Time-Delay Relay
with 30A Over-Current Protection
1N4148
330kΩ
12V
RESET
10µF +
MIC5013
330kΩ
R
330kΩ
20kΩ
1 Input
Fault 8
2 Thresh
V+ 7
3 Sense Gate 6
4 Source Gnd 5
IRCZ44
SOURCE
SENSE
43Ω
1N4148
KEL VIN
4.3kΩ
100nF
T
ST A R T
M
12V
RUN
STOP
Figure 13. Motor Stall
Shutdown
July 2005
13
MIC5013
MIC5013
Micrel, Inc.
Applications Information (Continued)
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.
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
+
V
Q3
Q5
Q1
125pF
125pF
COM
C1
C1
100 kHz
OSCILLATOR
C2
C2
Q2
G
Q4
500Ω
Q6
OFF
GATE CLAMP
ZENER
12.5V
S
ON
Figure 14. Gate Control
Circuit Detail
MIC5013
14
July 2005
MIC5013
Micrel, Inc.
Package Information
PIN 1
DIMENSIONS:
INCH (MM)
0.380 (9.65)
0.370 (9.40)
0.255 (6.48)
0.245 (6.22)
0.135 (3.43)
0.125 (3.18)
0.300 (7.62)
0.013 (0.330)
0.010 (0.254)
0.018 (0.57)
0.130 (3.30)
0.100 (2.54)
0.0375 (0.952)
0.380 (9.65)
0.320 (8.13)
8-Pin Plastic DIP (N)
0.026 (0.65)
MAX)
PIN 1
0.157 (3.99)
0.150 (3.81)
DIMENSIONS:
INCHES (MM)
0.050 (1.27)
TYP
0.064 (1.63)
0.045 (1.14)
0.197 (5.0)
0.189 (4.8)
0.020 (0.51)
0.013 (0.33)
45°
0.0098 (0.249)
0.0040 (0.102)
0°–8°
0.010 (0.25)
0.007 (0.18)
0.050 (1.27)
0.016 (0.40)
SEATING
PLANE
0.244 (6.20)
0.228 (5.79)
8-Pin SOIC (M)
MICREL INC.
TEL
2180 FORTUNE DRIVE
SAN JOSE, CA 95131
USA
+ 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB http://www.micrel.com
This 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.
© 1998 Micrel, Inc.
July 2005
15
MIC5013