MIC5010 [MICREL]
Full-Featured High- or Low-Side MOSFET Driver; 全功能高或低侧MOSFET驱动器
| 型号： | MIC5010 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | Full-Featured High- or Low-Side MOSFET Driver |
| 文件： | 总16页 (文件大小：192K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC5010
Full-Featured High- or Low-Side MOSFET Driver
Not Recommended for New Designs
General Description
Features
The MIC5010 is the full-featured member of the Micrel
MIC501X driver family. These ICs are designed to drive the
gate of an N-channel power MOSFET above the supply rail
in high-side power switch applications. The MIC5010 is
compatible with standard or current-sensing power FETs in
both high- and low-side driver topologies.
• 7V to 32V operation
• Less than 1µA standby current in the “OFF” state
• Internal charge pump to drive the gate of an N-channel
power FET above supply
• Available in small outline SOIC packages
• Internal zener clamp for gate protection
• 25µs 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
The MIC5010 charges a 1nF load in 60µs typical and
protects the MOSFET from over-current conditions. Faster
switching is achieved by adding two 1nF charge pump
capacitors. The current sense trip point is fully program-
mable and a dynamic threshold allows high in-rush current
loads to be started. A fault pin indicates when the MIC5010
has turned off the FET due to excessive current.
Applications
Other members of the Micrel driver family include the
MIC5011 minimum parts count 8 pin driver, MIC5012 dual
driver, and MIC5013 protected 8 pin driver.
• Lamp drivers
• Relay and solenoid drivers
• Heater switching
• Power bus switching
• Motion control
• Half or full H-bridge drivers
5
Typical Application
Ordering Information
Part Number Temperature Range
Package
MIC5010BN
MIC5010BM
–40°C to +85°C
–40°C to +85°C
14-pin Plastic DIP
14-pin SOIC
+
MIC5010
V =24V
1
2
3
4
5
6
7
14
13
12
11
10
9
Inhibit Fault
NC
V+
NC
C1
+
Control Input
Input
Thresh
10µF
RTH
SR(
+100mV)
VTRIP
20kΩ
RS
=
Sense Com
R I – (
+100mV)
VTRIP
L
Source
Gnd
C2
+
SRRS
V
IRCZ44
8
Gate
R1=
RTH
(S=2590,
100mV (SR+RS)
R=11mΩ)
2200
SOURCE
RS
=
–1000
SENSE
VTRIP
43Ω
LOAD
KELVIN
For this example:
Note: The MIC5010 is ESD sensitive.
R1
4.3kΩ
IL =30A (trip current)
V
TRIP =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
April 1998
5-87
MIC5010
Micrel
Absolute Maximum Ratings (Note 1, 2)
Operating Ratings (Notes 1, 2)
Inhibit Voltage, Pin 1
Input Voltage, Pin 3
Threshold Voltage, Pin 4
Sense Voltage, Pin 5
Source Voltage, Pin 6
Current into Pin 6
–1V to V+
Power Dissipation
1.56W
80 °C/W
115°C/W
–10V to V+
– 0.5 to +5V
–10V to V+
–10V to V+
50 mA
θ
θ
(Plastic DIP)
(SOIC)
JA
JA
Ambient Temperature: B version
Storage Temperature
Lead Temperature
–40°C to +85°C
–65°C to +150°C
260°C
Gate Voltage, Pin 8
Supply Voltage (V ), Pin 13
Fault Output Current, Pin 14
Junction Temperature
–1V to 50V
–0.5V to 36V
–1mA to +1mA
150°C
(Soldering, 10 seconds)
Supply Voltage (V ), Pin 13
+
+
7V to 32V high side
7V to 15V low side
Pin Description (Refer to Figures 1 and 2)
Pin Number
Pin Name
Pin Function
1
Inhibit
Inhibits current sense function when connected to supply. Normally
grounded.
3
4
Input
Resets current sense latch and turns on power MOSFET when taken above
threshold (3.5V typical). Pin 3 requires <1µA to switch.
Threshold
Sets current sense trip voltage according to:
2200
V
=
TRIP
R
+1000
TH
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.
5
6
Sense
The sense pin causes the current sense to trip when VSENSE is VTRIP above
VSOURCE. Pin 5 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.
Source
Reference for the current sense voltage on pin 5 and return for the gate
clamp zener. Connect to the load side of current shunt or kelvin lead of
current sensing FET. Pins 5 and 6 can safely swing to –10V when turning
off inductive loads.
7
8
Ground
Gate
Drives and clamps the gate of the power FET. Pin 8 will be clamped to
approximately –0.7V by an internal diode when turning off inductive loads.
9, 10, 11
13
C2, Com, C1
V+
Optional 1nF capacitors reduce gate turn-on time; C2 has dominant effect.
Supply pin; must be decoupled to isolate from large transients caused by
the power FET drain. 10µF is recommended close to pins 13 and 7.
14
Fault
Outputs status of protection circuit when pin 3 is high. Fault low indicates
normal operation; fault high indicates current sense tripped.
Pin Configuration
MIC5010
1
2
3
4
5
6
7
14
13
12
11
10
Inhibit Fault
NC
V+
NC
C1
Input
Thresh
Sense Com
Source C2
9
8
Gnd
Gate
5-88
April 1998
MIC5010
Micrel
Electrical Characteristics (Note 3) Test circuit. TA = –55°C to +125°C, V+ = 15V, V1 = 0 V, I4 = I = I = 0, all
5
14
switches open, unless otherwise specified.
Parameter
Conditions
Min Typical Max
Units
Supply Current, I13
V+ = 32V
VIN = 0V, S4 closed
VIN = VS = 32V, I4 = 200µA
Adjust VIN for VGATE low
Adjust VIN for VGATE high
Adjust VIN for VGATE high
VIN = 0V
0.1
8
10
20
2
µA
mA
V
Logic Input Voltage, VIN
Logic Input Current, I3
V+ = 4.75V
4.5
5.0
–1
V
V+ = 15V
V+ = 32V
V
µA
µA
pF
V
VIN = 32V
1
Input Capacitance
Gate Drive, VGATE
Pin 3
5
15
S1, S2 closed,
VS = V+, VIN = 5V
S2 closed, VIN = 5V
V+ = 7V, I8 = 0
13
24
11
11
V+ = 15V, I8 = 100 µA
V+ = 15V, VS = 15V
V+ = 32V, VS = 32V
27
V
Zener Clamp,
12.5
13
15
16
50
V
VGATE – VSOURCE
V
Gate Turn-on Time, tON
(Note 4)
VIN switched from 0 to 5V; measure time
for VGATE to reach 20V
25
µs
Gate Turn-off Time, tOFF
VIN switched from 5 to 0V; measure time
for VGATE to reach 1V
4
10
µs
Threshold Bias Voltage, V4
Current Sense Trip Voltage,
VSENSE – VSOURCE
I4 = 200 µA
1.7
75
2
2.2
135
130
270
260
680
650
V
S2 closed, VIN = 5V,
Increase I5
V+ = 7V,
S4 closed
VS = 4.9V
S4 closed
VS = 11.8V
VS = 0V
105
100
210
200
520
500
2.1
mV
mV
mV
mV
mV
mV
V
5
I4 = 100 µA
V+ = 15V
70
150
140
360
350
1.6
I4 = 200 µA
V+ = 32V
I4 = 500 µA
VS = 25.5V
Peak Current Trip Voltage,
VSENSE – VSOURCE
S3, S4 closed,
V+ = 15V, VIN = 5V
Fault Output Voltage, V14
VIN = 0V, I14 = –100 µA
0.4
14.6
7.5
1
1
V
V
V
V
VIN = 5V, I14 = 100 µA, current sense tripped
V1 above which current sense is disabled
Minimum possible V1
14
Current Sense Inhibit, V1
13
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 T = 25°C and T = 85°C, and 100% guaranteed over the entire
A
A
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.
April 1998
5-89
MIC5010
Micrel
Test Circuit
V+
+
1µF
I5
V1
MIC5010
1
2
3
4
5
6
7
14
13
12
11
10
9
Inhibit Fault
NC
V+
NC
C1
I14
Input
Thresh
V3
1nF
1nF
50Ω
Sense Com
Source C2
500Ω
1W
8
3.5k
Gnd
Gate
S3 I4
1nF
S1
S4 S2
I8
VS
Typical Characteristics
Supply Current
DC Gate Voltage
above Supply
14
12
10
8
12
10
8
6
6
4
4
2
0
2
0
0
3
6
9
12
15
0
5
10 15 20 25 30 35
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
5-90
April 1998
MIC5010
Micrel
Typical Characteristics (Continued)
High-side Turn-on Time*
High-side Turn-on Time*
350
140
120
100
80
300
C
GATE
=1 nF
C
GATE
=1 nF
250
200
150
100
50
C2=1 nF
60
40
20
0
0
0
3
6
9
12
15
0
3
6
9
12
15
15
30
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
High-side Turn-on Time*
High-side Turn-on Time*
3.5
3.0
2.5
2.0
1.5
1.0
0.5
1.4
1.2
1.0
0.8
0.6
0.4
0.2
C
GATE
=10 nF
C
=10 nF
GATE
5
C2=1 nF
0
0
0
3
6
9
12
15
0
3
6
9
12
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
Charge Pump
Output Current
Charge Pump
Output Current
250
200
150
100
50
1.0
0.8
+
V
=V
GATE
+
V
=V
GATE
0.6
0.4
+
=V +5V
V
GATE
+
=V +5V
V
GATE
0.2
0
C2=1 nF
VS=V –5V
+
VS=V –5V
+
0
0
5
10
15 20 25
30
0
5
10
15 20 25
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
+
+
* Time for gate to reach V + 5V in test circuit with VS = V – 5V (prevents gate clamp from interfering with measurement).
April 1998
5-91
MIC5010
Micrel
Typical Characteristics (Continued)
Turn-on Time
Turn-off Time
2.0
1.75
1.5
50
C
GATE
=10 nF
40
30
20
1.25
1.0
C
=1 nF
12
10
GATE
0.75
0.5
0
0
3
6
9
15
15
15
–25
0
25
50 75 100 125
SUPPLY VOLTAGE (V)
DIE TEMPERATURE (°C)
Low-side Turn-on Time
for Gate = 5V
Low-side Turn-on Time
for Gate = 5V
1000
300
100
30
1000
300
100
30
C2=1 nF
C
GATE
=10 nF
C
GATE
=10 nF
10
10
C
=1 nF
GATE
C
=1 nF
GATE
3
3
1
1
0
3
6
9
12
0
3
6
9
12
15
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
Low-side Turn-on Time
for Gate = 10V
Low-side Turn-on Time
for Gate = 10V
3000
1000
300
100
30
3000
1000
300
100
30
C2=1 nF
C
GATE
=10 nF
C
GATE
=10 nF
C
GATE
=1 nF
C
=1 nF
GATE
10
10
3
0
3
3
6
9
12
15
0
3
6
9
12
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
5-92
April 1998
MIC5010
Micrel
AresistorR frompin4togroundsetsI4,andhenceV
.
Applications Information
Functional Description (Refer to Block Diagram)
TH
TRIP
An additional capacitor C from pin 4 to ground creates a
TH
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.
The various MIC5010 functions are controlled via a logic
block connected to the input pin 3. When the input is low all
functionsareturnedoffforlowstandbycurrent,andthegate
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
powerFET. Abandgaptypevoltageregulatorisalsoturned
on which biases the current sense circuitry.
When the current sense has tripped, the fault pin 14 will be
highaslongastheinputpin3remainshigh. However, when
the input is low the fault pin will also be low.
Construction Hints
High current pulse circuits demand equipment and assem-
bly techniques that are more stringent than normal, low
current lab practices. The following are the sources of
common pitfalls encountered while prototyping:Supplies:
many bench power supplies have poor transient response.
Circuitsthatarebeingpulsetested, orthosethatoperateby
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 volt-
age that appears at the drain of a high-side driver (or the
supply side of the load in a low-side driver) with an oscillo-
scope. 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—withpossiblycatastrophicresults. A10µFsup-
ply bypass capacitor at the chip is recommended.
The charge pump incorporates a 100kHz oscillator and on-
chip pump capacitors capable of charging 1 nF to 5V above
supply in 60µS typical. With the addition of 1nF capacitors
at C1 and C2, the turn-on time is reduced to 25µS typical.
The charge pump is capable of pumping thegate up to over
twice the supply voltage. For this reason a zener clamp
(12.5V typical) is provided between the gate pin 8 and the
source pin 6 to prevent exceeding the V
MOSFET at high supplies.
rating of the
GS
The current sense operates by comparing the sense volt-
age at pin 5 to an offset version of the source voltage at pin
6. Current I4 flowing in threshold pin 4 is mirrored and
returned to the source via a 1kΩ resistor to set the offset or
tripvoltage.When(V
–V
)exceedsV
,the
SENSE
SOURCE
TRIP
current sense trips and sets the current sense latch to turn
off the power FET. An integrating comparator is used to
reducesensitivitytospikesonpin5.Thelatchisresettoturn
the FET back on by “recycling” the input pin 3 low and then
high again.
5
Block Diagram
V+
13
C1 Com C2
11 10
9
CHARGE
PUMP
Gate
8
500Ω
Input 3
LOGIC
V+
12.5V
CURRENT
SENSE
LATCH
MIC5010
R
Q
Sense
5
6
+
-
Fault
14
S
I4
+
VTRIP
-
1k
TEMP
SENSE
V. REG
Source
1k
7
1
4
Ground
Inhibit Threshold
April 1998
5-93
MIC5010
Micrel
500mV (R = 3.3kΩ to 20kΩ). Thresholds at the high end
offer the best noise immunity, but also compromise switch
Applications Information (Continued)
TH
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
carelessconstructiontechniquescouldeasilyadd50to100
mΩ 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 un-
der load.
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
afewmillivolts), andthresholdbiasvoltage(V ). Thevalues
4
shown in Figure 2 are designed for a trip current of 20
amperes. It is important to ground pin 6 at the current shunt
R , to eliminate the effects of ground resistance.
S
A key advantage of the low-side topology is that the load
Circuit Topologies
supplyislimitedonlybytheMOSFETBV
rating. Clamp-
DSS
The MIC5010 is suited for use in high- or low-side driver
applications with over-current protection for both current-
sensing and standard MOSFETs. In addition, the MIC5010
works well in applications where, for faster switching times,
the supply is bootstrapped from the MOSFET source out-
put. 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
ing may be required to protect the MOSFET drain terminal
from inductive switching transients. The MIC5010 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
immediatelywhencommandedON.Typicalcircuitsachieve
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 ) on top of the load. R1 and R2
S
add a small, additional potential to V
to prevent false-
TRIP
sameforallcircuits(lessthan10µstoV =1V).Thechoice
GS
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.
of one topology over another is based on a combination of
considerations including speed, voltage, and desired sys-
tem characteristics. Each topology is described in this
section. Note that I , as used in the design equations, is the
L
load current that just trips the over-current comparator.
Low-SideDriverwithCurrentShunt(Figure2). Theover-
current comparator monitors R and trips if I × R exceeds
S
L
S
High-side drivers implemented with MIC501X drivers are
V
. R is selected to produce the desired trip voltage.
TRIP
TH
As a guideline, keep V
within the limits of 100mV and
TRIP
+
V
V =7 to 15V
LOAD
MIC5010
Inhibit Fault
1
2
3
4
5
6
7
14
13
12
11
10
9
VTRIP
IL
NC
V+
RS=
+
NC
C1
Control Input
Input
10µF
2200
RTH
RTH
=
–1000
Thresh
V
LOAD
10kΩ
TRIP
Sense Com
For this example:
I =20A (trip current)
Source
Gnd
C2
8
Gate
IRF540
L
VTRIP = 200mV
RS
10mΩ
IRC 4LPW-5
(International Resistive Company)
Figure 2. Low-Side Driver with
Current Shunt
5-94
April 1998
MIC5010
Micrel
Applications Information (Continued)
+
MIC5010
Inhibit Fault
V =24V
+
1
2
3
4
5
6
7
14
13
12
11
10
9
V
R1=
1mA
NC
V+
NC
C1
+
Control Input
Input
Thresh
R2=100Ω
10µF
RTH
20kΩ
100mV+
IL
V
Sense Com
TRIP
RS
=
Source
Gnd
C2
8
2200
Gate
IRF541
RS
–1000
RTH
=
V
TRIP
100Ω
R2
For this example:
18mΩ
IRC 4LPW-5*
IL =10A (trip current)
V
TRIP =100mV
R1
24kΩ
LOAD
*International Resistive Company
Figure 3. High-Side Driver
with Current Shunt
self-protected against inductive switching transients. Dur-
ing 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.
TheMIC5010sourceandsensepins(5and6)aredesigned
towithstandthisnegativeexcursionwithoutdamage.Exter-
nal clamp diodes are unnecessary, but may be added to
reduce power dissipation in the MOSFET.
bodyresistance“R”ofthemainsourcepin. Currentsensing
MOSFETseliminatethecurrentshuntrequiredbystandard
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
5
estimated. V
must be less than R × I , or else R will
TRIP
L S
become negative. Substituting a MOSFET with higher on-
resistance, or reducing V fixes this problem. V
=
TRIP
TRIP
Current Shunts (R ). Low-valued resistors are necessary
100 to 200mV is suggested. Although the load supply is
limited only by MOSFET ratings, the MIC5010 supply
should be limited to 15V to prevent damage to the gate
clamp zener. Output clamping is necessary for inductive
loads.
S
for use at R .Values for R range from 5 to 50mΩ, at 2 to
S
S
10W. Worthy of special mention are Kelvin-sensed, “four-
†
terminal” units supplied by a number of manufacturers .
Kelvin-sensed resistors eliminate errors that are caused by
lead and terminal resistances, and simplify product assem-
bly. 10% tolerance is normally adequate, and with shunt
potentials of 200mV thermocouple effects are insignificant.
Temperature coefficient is important; a linear, 500ppm/°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 100ppm/°C.
“R” is the body resistance of the MOSFET, excluding bond
resistances. R
as specified on MOSFET data sheets
DS(ON)
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)bysimplyhalvingthestatedR
, or
for
DS(ON)
DS(ON)
DS(ON)
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 speci-
fiedwithasensingratio“S”whichdescribestherelationship
between the on-resistance of the sense connection and the
by subtracting 20 to 50mΩ from the stated R
smaller MOSFETs.
High-SideDriverwithCurrentSensingMOSFET(Figure
1). Thedesignstartsbydeterminingthevalueof“S”and“R”
for the MOSFET (use the guidelines described for the low-
side version). Let V
= 100 mV, and calculate R for a
TRIP
S
desired trip current. Next calculate R and R1. The trip
TH
†
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
April 1998
5-95
MIC5010
Micrel
Applications Information (Continued)
+
VLOAD
V =15V
MIC5010
Inhibit Fault
1
2
3
4
5
6
7
14
13
12
11
10
9
SRVTRIP
NC
RS =
V+
NC
C1
+
R IL – VTRIP
10µF
Control Input
Input
Thresh
RTH
2200
RTH=
–1000
LOAD
20kΩ
VTRIP
Sense Com
Source
Gnd
C2
IRCZ44
8
Gate
For this example:
(S=2590,
R=11mΩ)
I
L =20A (trip current)
SENSE
V
TRIP =100mV
RS
SOURCE
22Ω
KELVIN
Figure 4. Low-Side Driver with
Current-Sensing MOSFET
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.
by the lamp. R
acts to increase the current limit at turn-
TH2
ontoapproximately10timesthesteady-statelampcurrent.
The high initial trip point decays away according to a 20ms
time constant contributed by C . R
could be eliminated
TH TH2
Typical Applications
with C working against the internal 1kΩ resistor, but this
TH
Start-upintoaDeadShort.IftheMIC5010attemptstoturn
on a MOSFET when the load is shorted, a very high current
flows. Theover-currentshutdownwillprotecttheMOSFET,
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.
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
/C network to allow for lamp
TH2 TH
start-up. Let R
= (R
÷ 10) – 1kΩ, and choose a
TH2
TH1
capacitor that provides the desired time constant working
against R and the internal 1kΩ resistor.
TH2
When the MIC5010 is turned off, the threshold pin (4)
appears as an open circuit, and C is discharged through
TH
R
and R
. This is much slower than the turn-on time
TH1
TH2
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, owingtonoisefilteringinthecomparator. Adelay
of up to 100µs can be observed at the threshold of shut-
down. A20%overdrivereducesthedelaytonearminimum.
MIC5010
Inhibit Fault
12V
1
2
3
4
5
6
7
14
13
12
11
10
9
NC
V+
NC
C1
+
RTH2
1kΩ
Control Input
Input
Thresh
10µF
Incandescent Lamps. The cold filament of an incandes-
cent 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
hundredmilliseconds.Itisunwisetosettheover-currenttrip
pointto70Atoaccommodatesuchaload.A“resistive”short
that draws less than 70A could destroy the MOSFET by
allowing sustained, excessive dissipation. If the over-cur-
rent trip point is set to less than 70A, the MIC5010 will not
start a cold filament. The solution is to start the lamp with a
hightrippoint,butreducethistoareasonablevalueafterthe
lamp is hot.
RTH1
22kΩ
Sense Com
Source
Gnd
C2
8
IRCZ44
#6014
Gate
CTH
22µF
43Ω
3.9kΩ
The MIC5010 over-current shutdown circuit is designed to
handle this situation by varying the trip point with time (see
Figure 5. Time-Variable
Trip Threshold
Figure 5). R
functions in the conventional manner,
TH1
providingacurrentlimitofapproximatelytwicethatrequired
5-96
April 1998
MIC5010
Micrel
In a PWM application the chip supply is actually much
higher than the system supply, which improves switching
time.
Applications Information (Continued)
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 C
.
TH
Modifying Switching Times. Do not add external capaci-
tors to the gate to slow down the switching time. Add a
resistor (1kΩ to 51kΩ) in series with the gate of the MOS-
FET to achieve this result.
=7 to 15V
VDD
MIC5010
Inhibit Fault
1N5817
1
2
3
4
5
6
7
14
13
12
11
10
9
External capacitors can be added at C1 and C2 for faster
switching times (see Block Diagram). Values of 100pF to
1nF produce useful speed increases. If component count is
critical, C2(pins9to10)canbeusedalonewithonlyasmall
loss of speed compared to using both capacitors.
NC
V+
1N4001 (2)
100nF
Control Input
+
NC
C1
Input
10µF
Thresh
20kΩ
Sense Com
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-
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
Source
Gnd
C2
8
Gate
IRF540
100Ω
18mΩ
+
+
discharge and the MIC5010 supply pin will fall to V = V
V
DD
R1=
LOAD
– 1.4. Under this condition pins 5 and 6 will be held above
1mA
+
V and may false trigger the over-current circuit. A larger
capacitor will lengthen the maximum “on” time; 1000µF will
holdthecircuitupfor2.5seconds,butrequiresmorecharge
time when the circuit is turned off. The optional Schottky
barrier diode improves turn-on time on supplies of less than
10V.
Figure 6. Bootstrapped
High-Side Driver
5
ElectronicCircuitBreaker(Figure7).TheMIC5010forms
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
Since the supply current in the “off” state is only a small
leakage, the 100nF bypass capacitor tends to remain
chargedforseveralsecondsaftertheMIC5010isturnedoff.
12V
12V
100kΩ 100kΩ
100kΩ
10kΩ
MIC5010
Inhibit Fault
100nF
1
2
3
4
5
6
7
14
13
NC
V+
NC
C1
+
12
11
10
9
Input
Thresh
MPSA05
10µF
20kΩ
Sense Com
Source
Gnd
C2
8
Gate
IRFZ40
100Ω
22mΩ
CPSL-3 (Dale)
1N4148
10kΩ
LOAD
Figure 7. 10-Ampere
Electronic Circuit Breaker
April 1998
5-97
MIC5010
Micrel
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 prece-
dence.Ifthereisafaultconditionthecircuitwilllatchoff,and
it can be reset by pushing the “on” button.
Applications Information (Continued)
15V
33kΩ
33pF
Thisapplicationalsoillustrateshowtwo(ormore)MOSFETs
canbeparalleled. Thisreducestheswitchdrop, anddistrib-
utes the switch dissipation into multiple packages.
To MIC5010 Input
MPSA05
100kΩ
High-VoltageBootstrap(Figure10).AlthoughtheMIC5010
is limited to operation on 7 to 32V supplies, a floating
bootstrap arrangement can be used to build a high-side
switchthatoperatesonmuchhighervoltages.TheMIC5010
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.
4N35
10mA
Control Input
100kΩ
1kΩ
Figure 8. Improved
Opto-Isolator Performance
Power for the MIC5010 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 MIC5010 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.
occurs, the circuit breaker shuts off. The breaker tests the
loadevery18msuntiltheshortisremoved,atwhichtimethe
circuit latches ON. No reset button is necessary.
Opto-Isolated Interface (Figure 8). Although the MIC5010
has no special input slew rate requirement, the lethargic
transitions provided by an opto-isolator may cause oscilla-
tions 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
MIC5010 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 MIC5010
will turn OFF.
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 dissipa-
tion and, in the case of the MIC5010, could trip the over-
current comparator. Speed is also important, since PWM
control requires the outputs to switch in the 2 to 20kHz
range.
Fault-Protected Industrial Switch (Figure 9). The most
commonmanualcontrolforindustrialloadsisapushbutton
on/off switch. The “on” button is physically arranged in a
recess so that in a panic situation the “off” button, which
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
24V
24V
MIC5010
Inhibit Fault
100kΩ
1
2
3
4
5
6
7
14
13
12
11
10
9
NC
V+
ON
+
CR2943-NA102A
(GE)
NC
C1
Input
10µF
Thresh
OFF
20kΩ
Sense Com
Source
Gnd
C2
8
Gate
IRFP044 (2)
100Ω
5mΩ
LVF-15 (RCD)
330kΩ
15kΩ
LOAD
Figure 9. 50-Ampere
Industrial Switch
5-98
April 1998
MIC5010
Micrel
Applications Information (Continued)
15V
1N4003 (2)
MIC5010
Inhibit Fault
1
14
13
12
11
10
1N4746
2
3
4
V+
33kΩ
NC
33pF
+
NC
Input
100µF
90V
MPSA05
100kΩ
Thresh
Sense
Source
Gnd
C1
6.2kΩ
5
6
Com
4N35
10mA
9
8
C2
1nF
Control Input
100kΩ
7
Gate
IRFP250
1kΩ
10mΩ
KC1000-4T
(Kelvin)
100nF
200V
1/4 HP, 90V
5BPB56HAA100
(GE)
1N4003
M
15Vp-p, 20kHz
Squarewave
Figure 10. High-Voltage
Bootstrapped Driver
cross conduction. Both the top- and bottom-side drivers are
protected, so the output can be shorted to either rail without
damage.
couldbeindependentlydrivenfromanexternalsourcesuch
as a switch or another high-side driver to give a delay
relative to some other event in the system.
5
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%.
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 3 to
ground.
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.
Motor Driver with Stall Shutdown (Figure 13). Tachom-
eter 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 MIC5010 input ON. If the motor slows down, the tach
output is reduced, and the MIC5010 switches OFF. Resis-
tor “R” sets the shutdown threshold. If the output current
exceeds 30A, the MIC5010 shuts down and remains in that
condition until the momentary “RESET” button is pushed.
Control is then returned to the START/RUN/STOP switch.
If current feedback is required for torque control, it is
available in chopped form at the bottom-side driver's 22mΩ
current-sensing resistor.
Time-Delay Relay (Figure 12). The MIC5010 forms the
basis of a simple time-delay relay. As shown, the delay
commenceswhenpowerisapplied, butthe100kΩ/1N4148
April 1998
5-99
MIC5010
Micrel
Applications Information (Continued)
15V
MIC5010
Inhibit Fault
1N5817
1
2
3
4
5
6
7
14
13
12
11
10
9
1N4148
NC
V+
1N4001 (2)
100nF
+
NC
C1
Input
220pF
20kΩ
22kΩ
1µF
Thresh
Sense Com
Source
Gnd
C2
8
Gate
IRF541
100Ω
22mΩ
CPSL-3
(Dale)
15kΩ
PWM
INPUT
15V
12V,
10A Stalled
M
MIC5010
Inhibit Fault
1
14
13
12
11
10
9
2
3
4
5
6
7
NC
V+
NC
C1
+
10kΩ
10µF
Input
Thresh
22kΩ
1nF
10kΩ
Sense Com
2N3904
Source
Gnd
C2
8
Gate
IRF541
22mΩ
CPSL-3
(Dale)
Figure 11. Half-Bridge
Motor Driver
5-100
April 1998
MIC5010
Micrel
Applications Information (Continued)
MIC5010
Inhibit Fault
12V
1
14
13
12
11
10
9
2
3
4
5
6
7
NC
V+
NC
C1
100kΩ
+
1N4148
Input
Thresh
10µF
20kΩ
Sense Com
Source
Gnd
C2
IRCZ44
8
Gate
+
OUTPUT
(Delay=5S)
100µF
10kΩ
43Ω
100Ω
4.3kΩ
Figure 12. Time-Delay Relay
with 30A Over-Current Protection
5
1N4148
330kΩ
MIC5010
Inhibit Fault
12V
RESET
1
2
3
4
5
6
7
14
13
12
11
10
9
NC
V+
NC
C1
+
Input
Thresh
10µF
330kΩ
R
330kΩ
20kΩ
Sense Com
Source
Gnd
C2
8
IRCZ44
Gate
43Ω
1N4148
4.3kΩ
100nF
M
T
12V
START
RUN
STOP
Figure 13. Motor Stall
Shutdown
April 1998
5-101
MIC5010
Micrel
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.
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).
In a low-side application operating on a 12 to 15V supply,
theMOSFETisfullyenhancedbytheactionofQ5alone.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.
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 MOS-
FET off.
Q6 is turned off when the MIC5010 is commanded on. Q5
pulls the gate up to supply (through 2 diodes). Next, the
chargepumpbeginssupplyingcurrenttothegate. Thegate
acceptschargeuntilthegate-sourcevoltagereaches12.5V
and is clamped by the zener diode.
The action of Q5 makes the MIC5010 operate quickly in
low-side applications. In high-side applications Q5
prechargestheMOSFETgatetosupply, leavingthecharge
pump to carry the gate up to full enhancement 10V above
supply. Bootstrapped high-side drivers are as fast as low-
side drivers since the chip supply is boosted well above the
drain at turn-on.
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
C2
C2
C1
COM
C1
G
S
Q2
100 kHz
OSCILLATOR
Q4
500Ω
GATE CLAMP
ZENER
12.5V
OFF
ON
Q6
Figure 14. Gate Control
Circuit Detail
5-102
April 1998
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