MIC4421/4422
Micrel
5-42
April 1998
MIC4421/4422
9A-Peak Low-Side MOSFET Driver
Bipolar/CMOS/DMOS
Process
General Description
MIC4421 and MIC4422 MOSFET drivers are rugged, effi-
cient, and easy to use. The MIC4421 is an inverting driver,
while the MIC4422 is a non-inverting driver.
Both versions are capable of 9A (peak) output and can drive
the largest MOSFETs with an improved safe operating mar-
gin. The MIC4421/4422 accepts any logic input from 2.4V to
V
S
without external speed-up capacitors or resistor net-
works. Proprietary circuits allow the input to swing negative
by as much as 5V without damaging the part. Additional
circuits protect against damage from electrostatic discharge.
MIC4421/4422 drivers can replace three or more discrete
components, reducing PCB area requirements, simplifying
product design, and reducing assembly cost.
Modern Bipolar/CMOS/DMOS construction guarantees free-
dom from latch-up. The rail-to-rail swing capability of CMOS/
DMOS insures adequate gate voltage to the MOSFET dur-
ing power up/down sequencing. Since these devices are
fabricated on a self-aligned process, they have very low
crossover current, run cool, use little power, and are easy to
drive.
Features
BiCMOS/DMOS Construction
Latch-Up Proof: Fully Isolated Process is Inherently
Immune to Any Latch-up.
Input Will Withstand Negative Swing of Up to 5V
Matched Rise and Fall Times ............................... 25ns
High Peak Output Current .............................. 9A Peak
Wide Operating Range .............................. 4.5V to 18V
High Capacitive Load Drive ........................... 47,000pF
Low Delay Time ........................................... 30ns Typ.
Logic High Input for Any Voltage from 2.4V to V
S
Low Equivalent Input Capacitance (typ) ................. 7pF
Low Supply Current .............. 450
A With Logic 1 Input
Low Output Impedance ........................................ 1.5
Output Voltage Swing to Within 25mV of GND or V
S
Applications
Switch Mode Power Supplies
Motor Controls
Pulse Transformer Driver
Class-D Switching Amplifiers
Line Drivers
Driving MOSFET or IGBT Parallel Chip Modules
Local Power ON/OFF Switch
Pulse Generators
Functional Diagram
IN
OUT
MIC4421
INVERTING
MIC4422
NON-INVERTING
0.1mA
0.3mA
2k
V
S
GND
MIC4421/4422
Micrel
April 1998
5-43
5
Ordering Information
Part No.
Temperature Range
Package
Configuration
MIC4421CN
0
C to +70
C
8-Pin PDIP
Inverting
MIC4421BN
40
C to +85
C
8-Pin PDIP
Inverting
MIC4421CM
0
C to +70
C
8-Pin SOIC
Inverting
MIC4421BM
40
C to +85
C
8-Pin SOIC
Inverting
MIC4421CT
0
C to +70
C
5-Pin TO-220
Inverting
MIC4422CN
0
C to +70
C
8-Pin PDIP
Non-Inverting
MIC4422BN
40
C to +85
C
8-Pin PDIP
Non-Inverting
MIC4422CM
0
C to +70
C
8-Pin SOIC
Non-Inverting
MIC4422BM
40
C to +85
C
8-Pin SOIC
Non-Inverting
MIC4422CT
0
C to +70
C
5-Pin TO-220
Non-Inverting
Pin Configurations
1
2
3
4
8
7
6
5
VS
OUT
OUT
GND
VS
IN
NC
GND
Plastic DIP (N)
SOIC (M)
TAB
5
OUT
4
GND
3
VS
2
GND
1
IN
TO-220-5 (T)
Pin Description
Pin Number
Pin Number
Pin Name
Pin Function
TO-220-5
DIP, SOIC
1
2
IN
Control Input
2, 4
4, 5
GND
Ground: Duplicate pins must be externally connected together.
3,
TAB
1, 8
V
S
Supply Input: Duplicate pins must be externally connected together.
5
6, 7
OUT
Output: Duplicate pins must be externally connected together.
3
NC
Not connected.
MIC4421/4422
Micrel
5-44
April 1998
Electrical Characteristics:
(T
A
= 25
C with 4.5 V
V
S
18 V unless otherwise specified.)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
INPUT
V
IH
Logic 1 Input Voltage
2.4
1.3
V
V
IL
Logic 0 Input Voltage
1.1
0.8
V
V
IN
Input Voltage Range
5
V
S
+0.3
V
I
IN
Input Current
0 V
V
IN
V
S
10
10
A
OUTPUT
V
OH
High Output Voltage
See Figure 1
V
S
.025
V
V
OL
Low Output Voltage
See Figure 1
0.025
V
R
O
Output Resistance,
I
OUT
= 10 mA, V
S
= 18 V
0.6
Output High
R
O
Output Resistance,
I
OUT
= 10 mA, V
S
= 18 V
0.8
1.7
Output Low
I
PK
Peak Output Current
V
S
= 18 V (See Figure 5)
9
A
I
DC
Continuous Output Current
2
A
I
R
Latch-Up Protection
Duty Cycle
2%
>1500
mA
Withstand Reverse Current
t
300
s
SWITCHING TIME (Note 3)
t
R
Rise Time
Test Figure 1, C
L
= 10,000 pF
20
75
ns
t
F
Fall Time
Test Figure 1, C
L
= 10,000 pF
24
75
ns
t
D1
Delay Time
Test Figure 1
15
60
ns
t
D2
Delay Time
Test Figure 1
35
60
ns
Power Supply
I
S
Power Supply Current
V
IN
= 3 V
0.4
1.5
mA
V
IN
= 0 V
80
150
A
V
S
Operating Input Voltage
4.5
18
V
Absolute Maximum Ratings
(Notes 1, 2 and 3)
Supply Voltage .............................................................. 20V
Input Voltage .................................. V
S
+ 0.3V to GND 5V
Input Current (V
IN
> V
S
) ............................................ 50 mA
Power Dissipation, T
A
25
C
PDIP .................................................................... 960mW
SOIC ................................................................. 1040mW
5-Pin TO-220 .............................................................. 2W
Power Dissipation, T
CASE
25
C
5-Pin TO-220 ......................................................... 12.5W
Derating Factors (to Ambient)
PDIP ................................................................ 7.7mW/
C
SOIC ............................................................... 8.3mW/
C
5-Pin TO-220 .................................................... 17mW/
C
Storage Temperature ............................... 65
C to +150
C
Lead Temperature (10 sec) ....................................... 300
C
Operating Ratings
Junction Temperature ............................................... 150
C
Ambient Temperature
C Version ................................................... 0
C to +70
C
B Version ................................................ 40
C to +85
C
Thermal Resistance
5-Pin TO-220
(
JC
) .............................................. 10
C/W
MIC4421/4422
Micrel
April 1998
5-45
5
Figure 1. Inverting Driver Switching Time
Electrical Characteristics:
(Over operating temperature range with 4.5V
V
S
18V unless otherwise specified.)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
INPUT
V
IH
Logic 1 Input Voltage
2.4
1.4
V
V
IL
Logic 0 Input Voltage
1.0
0.8
V
V
IN
Input Voltage Range
5
V
S
+0.3
V
I
IN
Input Current
0V
V
IN
V
S
10
10
A
OUTPUT
V
OH
High Output Voltage
Figure 1
V
S
.025
V
V
OL
Low Output Voltage
Figure 1
0.025
V
R
O
Output Resistance,
I
OUT
= 10mA, V
S
= 18V
0.8
3.6
Output High
R
O
Output Resistance,
I
OUT
= 10mA, V
S
= 18V
1.3
2.7
Output Low
SWITCHING TIME (Note 3)
t
R
Rise Time
Figure 1, C
L
= 10,000pF
23
120
ns
t
F
Fall Time
Figure 1, C
L
= 10,000pF
30
120
ns
t
D1
Delay Time
Figure 1
20
80
ns
t
D2
Delay Time
Figure 1
40
80
ns
POWER SUPPLY
I
S
Power Supply Current
V
IN
= 3V
0.6
3
mA
V
IN
= 0V
0.1
0.2
V
S
Operating Input Voltage
4.5
18
V
NOTE 1:
Functional operation above the absolute maximum stress ratings is not implied.
NOTE 2:
Static-sensitive device. Store only in conductive containers. Handling personnel and equipment should be grounded to
prevent damage from static discharge.
NOTE 3:
Switching times guaranteed by design.
Test Circuits
IN
MIC4421
OUT
15000pF
V
S
= 18V
0.1F
4.7F
0.1F
IN
MIC4422
OUT
15000pF
V
S
= 18V
0.1F
4.7F
0.1F
t
D1
90%
10%
t
F
10%
0V
5V
t
D2
t
R
V
S
OUTPUT
INPUT
90%
0V
t
PW
0.5s
2.5V
t
PW
90%
10%
t
R
10%
0V
5V
t
F
V
S
OUTPUT
INPUT
90%
0V
t
PW
0.5s
t
D1
t
D2
t
PW
2.5V
Figure 2. Noninverting Driver Switching Time
MIC4421/4422
Micrel
5-46
April 1998
4
6
8
10
12
14
16
18
220
200
180
160
140
120
100
80
60
40
0
SUPPLY VOLTAGE (V)
RISE TIME (ns)
Rise Time
vs. Supply Voltage
20
22,000pF
10,000pF
47,000pF
4
6
8
10
12
14
16
18
220
200
180
160
140
120
100
80
60
40
0
SUPPLY VOLTAGE (V)
FALL TIME (ns)
Fall Time
vs. Supply Voltage
20
22,000pF
10,000pF
47,000pF
60
50
40
30
20
10
0
TEMPERATURE (
C)
TIME (ns)
Rise and Fall Times
vs. Temperature
-40
0
40
80
120
C
L
= 10,000pF
V
S
= 18V
t
FALL
t
RISE
100
1000
10k
100k
300
250
200
150
100
50
0
CAPACITIVE LOAD (pF)
RISE TIME (ns)
Rise Time
vs. Capacitive Load
18V
10V
5V
100
1000
10k
100k
300
250
200
150
100
50
0
CAPACITIVE LOAD (pF)
FALL TIME (ns)
Fall Time
vs. Capacitive Load
18V
10V
5V
4
6
8
10
12
14
16
18
10
-7
10
-8
10
-9
VOLTAGE (V)
CROSSOVER ENERGY (As)
Crossover Energy
vs. Supply Voltage
PER TRANSITION
100
1000
10k
100k
75
30
0
CAPACITIVE LOAD (pF)
SUPPLY CURRENT (mA)
Supply Current
vs. Capacitive Load
15
45
60
V
S
= 5V
50kHz
1 MHz
200kHz
100
1000
10k
100k
220
160
100
40
0
CAPACITIVE LOAD (pF)
SUPPLY CURRENT (mA)
Supply Current
vs. Capacitive Load
20
60
80
120
140
180
200
V
S
= 18V
50kHz
200kHz
1 MHz
100
1000
10k
100k
150
60
0
CAPACITIVE LOAD (pF)
SUPPLY CURRENT (mA)
Supply Current
vs. Capacitive Load
30
90
120
V
S
= 12V
50kHz
1 MHz
200kHz
Typical Characteristic Curves
MIC4421/4422
Micrel
April 1998
5-47
5
10k
100k
1M
10M
120
100
40
0
FREQUENCY (Hz)
SUPPLY CURRENT (mA)
Supply Current
vs. Frequency
20
60
80
V
S
= 12V
0.1F
0.01F
1000pF
10k
100k
1M
10M
60
50
20
0
FREQUENCY (Hz)
SUPPLY CURRENT (mA)
Supply Current
vs. Frequency
10
30
40
V
S
= 5V
0.1F
0.01F
1000pF
4
6
8
10
12
14
16
18
50
40
30
20
0
SUPPLY VOLTAGE (V)
TIME (ns)
Propagation Delay
vs. Supply Voltage
10
t
D2
t
D1
0
2
4
6
8
10
120
110
100
70
60
50
40
30
20
10
0
INPUT (V)
TIME (ns)
Propagation Delay
vs. Input Amplitude
80
90
t
D2
t
D1
V
S
= 10V
-40
0
40
80
120
1000
100
10
TEMPERATURE (
C)
QUIESCENT SUPPLY CURRENT (A)
Quiescent Supply Current
vs. Temperature
INPUT = 0
INPUT = 1
V
S
= 18V
4
6
8
10
12
14
16
18
2.4
2.2
2.0
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
SUPPLY VOLTAGE (V)
HIGH-STATE OUTPUT RESISTANCE (
)
High-State Output Resist.
vs. Supply Voltage
1.6
1.8
T
J
= 25
C
T
J
= 150
C
4
6
8
10
12
14
16
18
2.4
2.2
2.0
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
SUPPLY VOLTAGE (V)
LOW-STATE OUTPUT RESISTANCE (
)
Low-State Output Resist.
vs. Supply Voltage
1.6
1.8
T
J
= 25
C
T
J
= 150
C
-40
0
40
80
120
50
40
30
20
10
0
TEMPERATURE (
C)
TIME (ns)
Propagation Delay
vs. Temperature
t
D2
t
D1
Typical Characteristic Curves (Cont.)
10k
100k
1M
10M
180
160
100
40
0
FREQUENCY (Hz)
SUPPLY CURRENT (mA)
Supply Current
vs. Frequency
20
60
80
120
140
V
S
= 18V
0.1F
0.01F
1000pF
MIC4421/4422
Micrel
5-48
April 1998
Applications Information
Supply Bypassing
Charging and discharging large capacitive loads quickly
requires large currents. For example, charging a 10,000pF
load to 18V in 50ns requires 3.6A.
The MIC4421/4422 has double bonding on the supply pins,
the ground pins and output pins. This reduces parasitic lead
inductance. Low inductance enables large currents to be
switched rapidly. It also reduces internal ringing that can
cause voltage breakdown when the driver is operated at or
near the maximum rated voltage.
Internal ringing can also cause output oscillation due to
feedback. This feedback is added to the input signal since
it is referenced to the same ground.
Figure 3. Direct Motor Drive
Figure 4. Self Contained Voltage Doubler
30
29
28
27
26
25
0
50
100 150 200 250 300 350
mA
VOLTS
12
LINE
OUTPUT VOLTAGE vs LOAD CURRENT
DRIVE
LOGIC
1 DRIVE SIGNAL
CONDUCTION ANGLE
CONTROL 0
TO 180
CONDUCTION ANGLE
CONTROL 180
TO 360
MIC4451
VS
1F
VS
MIC4452
VS
1F
VS
1
M
3
2
PHASE 1 of 3 PHASE MOTOR
DRIVER USING MIC4420/4429
MIC4421
1F
50V
MKS 2
UNITED CHEMCON SXE
0.1F
WIMA
MKS 2
1
8
6, 7
5
4
0.1F
50V
5.6 k
560
+15
560F 50V
BYV 10 (x 2)
100F 50V
(x2) 1N4448
2
+
+
+
To guarantee low supply impedance over a wide frequency
range, a parallel capacitor combination is recommended for
supply bypassing. Low inductance ceramic disk capacitors
with short lead lengths (< 0.5 inch) should be used. A 1
F
low ESR film capacitor in parallel with two 0.1
F low ESR
ceramic capacitors, (such as AVX RAM Guard
), provides
adequate bypassing. Connect one ceramic capacitor di-
rectly between pins 1 and 4. Connect the second ceramic
capacitor directly between pins 8 and 5.
Grounding
The high current capability of the MIC4421/4422 demands
careful PC board layout for best performance. Since the
MIC4421 is an inverting driver, any ground lead impedance
will appear as negative feedback which can degrade switch-
ing speed. Feedback is especially noticeable with slow-rise
time inputs. The MIC4421 input structure includes about
200mV of hysteresis to ensure clean transitions and free-
dom from oscillation, but attention to layout is still recom-
mended.
Figure 5 shows the feedback effect in detail. As the MIC4421
input begins to go positive, the output goes negative and
several amperes of current flow in the ground lead. As little
as 0.05
of PC trace resistance can produce hundreds of
millivolts at the MIC4421 ground pins. If the driving logic is
referenced to power ground, the effective logic input level is
reduced and oscillation may result.
To insure optimum performance, separate ground traces
should be provided for the logic and power connections.
Connecting the logic ground directly to the MIC4421 GND
pins will ensure full logic drive to the input and ensure fast
output switching. Both of the MIC4421 GND pins should,
however, still be connected to power ground.
MIC4421/4422
Micrel
April 1998
5-49
5
Table 1: MIC4421 Maximum
Operating Frequency
V
S
Max Frequency
18V
220kHz
15V
300kHz
10V
640kHz
5V
2MHz
Conditions: 1.
JA
= 150
C/W
2. T
A
= 25
C
3. C
L
= 10,000pF
dissipation limit can easily be exceeded. Therefore, some
attention should be given to power dissipation when driving
low impedance loads and/or operating at high frequency.
The supply current vs. frequency and supply current vs
capacitive load characteristic curves aid in determining
power dissipation calculations. Table 1 lists the maximum
safe operating frequency for several power supply voltages
when driving a 10,000pF load. More accurate power dissi-
pation figures can be obtained by summing the three
dissipation sources.
Given the power dissipation in the device, and the thermal
resistance of the package, junction operating temperature
for any ambient is easy to calculate. For example, the
thermal resistance of the 8-pin plastic DIP package, from
the data sheet, is 130
C/W. In a 25
C ambient, then, using
a maximum junction temperature of 150
C, this package
will dissipate 960mW.
Accurate power dissipation numbers can be obtained by
summing the three sources of power dissipation in the
device:
Load Power Dissipation (P
L
)
Quiescent power dissipation (P
Q
)
Transition power dissipation (P
T
)
Calculation of load power dissipation differs depending on
whether the load is capacitive, resistive or inductive.
Resistive Load Power Dissipation
Dissipation caused by a resistive load can be calculated as:
P
L
= I
2
R
O
D
where:
I =
the current drawn by the load
R
O
=
the output resistance of the driver when the output is
high, at the power supply voltage used. (See data
sheet)
D =
fraction of time the load is conducting (duty cycle)
Figure 5. Switching Time Degradation Due to
Negative Feedback
MIC4421
1
8
6, 7
5
4
+18
0.1
F
0.1
F
TEK CURRENT
PROBE 6302
2,500 pF
POLYCARBONATE
5.0V
0 V
18 V
0 V
300 mV
6 AMPS
PC TRACE RESISTANCE = 0.05
LOGIC
GROUND
POWER
GROUND
WIMA
MKS-2
1
F
Input Stage
The input voltage level of the MIC4421 changes the quies-
cent supply current. The N channel MOSFET input stage
transistor drives a 320
A current source load. With a logic "1"
input, the maximum quiescent supply current is 400
A. Logic
"0" input level signals reduce quiescent current to 80
A
typical.
The MIC4421/4422 input is designed to provide 300mV of
hysteresis. This provides clean transitions, reduces noise
sensitivity, and minimizes output stage current spiking when
changing states. Input voltage threshold level is approxi-
mately 1.5V, making the device TTL compatible over the full
temperature and operating supply voltage ranges. Input
current is less than
10
A.
The MIC4421 can be directly driven by the TL494, SG1526/
1527, SG1524, TSC170, MIC38C42, and similar switch
mode power supply integrated circuits. By offloading the
power-driving duties to the MIC4421/4422, the power supply
controller can operate at lower dissipation. This can improve
performance and reliability.
The input can be greater than the V
S
supply, however, current
will flow into the input lead. The input currents can be as high
as 30mA p-p (6.4mA
RMS
) with the input. No damage will
occur to MIC4421/4422 however, and it will not latch.
The input appears as a 7pF capacitance and does not change
even if the input is driven from an AC source. While the device
will operate and no damage will occur up to 25V below the
negative rail, input current will increase up to 1mA/V due to
the clamping action of the input, ESD diode, and 1k
resistor.
Power Dissipation
CMOS circuits usually permit the user to ignore power
dissipation. Logic families such as 4000 and 74C have
outputs which can only supply a few milliamperes of current,
and even shorting outputs to ground will not force enough
current to destroy the device. The MIC4421/4422 on the other
hand, can source or sink several amperes and drive large
capacitive loads at high frequency. The package power
MIC4421/4422
Micrel
5-50
April 1998
Transition Power Dissipation
Transition power is dissipated in the driver each time its
output changes state, because during the transition, for a
very brief interval, both the N- and P-channel MOSFETs in
the output totem-pole are ON simultaneously, and a current
is conducted through them from V
S
to ground. The transition
power dissipation is approximately:
P
T
= 2 f V
S
(As)
where (As) is a time-current factor derived from the typical
characteristic curve "Crossover Energy vs. Supply Voltage."
Total power (P
D
) then, as previously described is just
P
D
= P
L
+ P
Q
+ P
T
Definitions
C
L
= Load Capacitance in Farads.
D = Duty Cycle expressed as the fraction of time the
input to the driver is high.
f = Operating Frequency of the driver in Hertz
I
H
= Power supply current drawn by a driver when both
inputs are high and neither output is loaded.
I
L
= Power supply current drawn by a driver when both
inputs are low and neither output is loaded.
I
D
= Output current from a driver in Amps.
P
D
= Total power dissipated in a driver in Watts.
P
L
= Power dissipated in the driver due to the driver's
load in Watts.
P
Q
= Power dissipated in a quiescent driver in Watts.
P
T
= Power dissipated in a driver when the output
changes states ("shoot-through current") in Watts.
NOTE: The "shoot-through" current from a dual
transition (once up, once down) for both drivers is
stated in Figure 7 in ampere-nanoseconds. This
figure must be multiplied by the number of repeti-
tions per second (frequency) to find Watts.
R
O
= Output resistance of a driver in Ohms.
V
S
= Power supply voltage to the IC in Volts.
Capacitive Load Power Dissipation
Dissipation caused by a capacitive load is simply the energy
placed in, or removed from, the load capacitance by the
driver. The energy stored in a capacitor is described by the
equation:
E = 1/2 C V
2
As this energy is lost in the driver each time the load is
charged or discharged, for power dissipation calculations the
1/2 is removed. This equation also shows that it is good
practice not to place more voltage in the capacitor than is
necessary, as dissipation increases as the square of the
voltage applied to the capacitor. For a driver with a capacitive
load:
P
L
= f C (V
S
)
2
where:
f = Operating Frequency
C = Load Capacitance
V
S
= Driver Supply Voltage
Inductive Load Power Dissipation
For inductive loads the situation is more complicated. For the
part of the cycle in which the driver is actively forcing current
into the inductor, the situation is the same as it is in the
resistive case:
P
L1
= I
2
R
O
D
However, in this instance the R
O
required may be either the
on resistance of the driver when its output is in the high state,
or its on resistance when the driver is in the low state,
depending on how the inductor is connected, and this is still
only half the story. For the part of the cycle when the inductor
is forcing current through the driver, dissipation is best
described as
P
L2
= I V
D
(1 D)
where V
D
is the forward drop of the clamp diode in the driver
(generally around 0.7V). The two parts of the load dissipation
must be summed in to produce P
L
P
L
= P
L1
+ P
L2
Quiescent Power Dissipation
Quiescent power dissipation (P
Q
, as described in the input
section) depends on whether the input is high or low. A low
input will result in a maximum current drain (per driver) of
0.2mA; a logic high will result in a current drain of
3.0mA.
Quiescent power can therefore be found from:
P
Q
= V
S
[D I
H
+ (1 D) I
L
]
where:
I
H
= quiescent current with input high
I
L
= quiescent current with input low
D = fraction of time input is high (duty cycle)
V
S
= power supply voltage
MIC4421/4422
Micrel
April 1998
5-51
5
MIC4421
1
8
6, 7
5
4
+18 V
0.1
F
0.1
F
TEK CURRENT
PROBE 6302
10,000 pF
POLYCARBONATE
5.0V
0 V
18 V
0 V
WIMA
MK22
1
F
2
Figure 6. Peak Output Current Test Circuit
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