MIC4421A/4422A
9A Peak Low-Side MOSFET Driver
Bipolar/CMOS/DMOS Process
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
June 2007
M9999-062707
General Description
MIC4421A and MIC4422A MOSFET drivers are rugged,
efficient, and easy to use. The MIC4421A is an inverting
driver, while the MIC4422A is a non-inverting driver.
Both versions are capable of 9A (peak) output and can
drive the largest MOSFETs with an improved safe
operating margin. The MIC4421A/4422A accepts any logic
input from 2.4V to V
S
without external speed-up capacitors
or resistor networks. 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.
MIC4421A/4422A 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
freedom from latch-up. The rail-to-rail swing capability of
CMOS/DMOS insures adequate gate voltage to the
MOSFET during 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.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
• High peak-output current: 9A Peak (typ.)
• Wide operating range: 4.5V to 18V (typ.)
• Minimum pulse width: 50ns
• Latch-up proof: fully isolated process is inherently
immune to any latch-up
• Input will withstand negative swing of up to 5V
• High capacitive load drive: 47,000pF
• Low delay time: 15ns (typ.)
• Logic high input for any voltage from 2.4V to V
S
• Low equivalent input capacitance: 7pF (typ.)
• Low supply current: 500µA (typ.)
• 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
___________________________________________________________________________________________________________
Typical Application
On
Off
VS OUT
OUT
MIC4422A
1µF
Si9410DY*
N-Channel
MOSFET
Load
Voltage
6
17
Load
0.1µF
VS
GNDIN
8
2 4,5
VS
+15V
0.1µF
* Siliconix 30m, 7A max.
†
Load voltage limited by MOSFET drain-to-source rating
Low-Side Power Sw itch
Micrel, Inc. MIC4421A/4422A
June 2007
2 M9999-062707
Ordering Information
Part Number
Standard Pb-Free
Configuration Temperature Range Package
MIC4421AAM* Inverting –55° to +125°C 8-Pin SOIC
MIC4421ABM MIC4421AYM Inverting –40° to +85°C 8-Pin SOIC
MIC4421ACM MIC4421AZM Inverting 0° to +70°C 8-Pin SOIC
MIC4421ABN MIC4421AYN Inverting –40° to +85°C 8-Pin PDIP
MIC4421ACN MIC4421AZN Inverting 0° to +70°C 8-Pin PDIP
MIC4421ACT MIC4421AZT Inverting 0° to +70°C 5-Pin TO-220
MIC4422AAM* Non-Inverting –55° to +125°C 8-Pin SOIC
MIC4422ABM MIC4422AYM Non-Inverting –40° to +85°C 8-Pin SOIC
MIC4422ACM MIC4422AZM Non-Inverting 0° to +70°C 8-Pin SOIC
MIC4422ABN MIC4422AYN Non-Inverting –40° to +85°C 8-Pin PDIP
MIC4422ACN MIC4422AZN Non-Inverting 0° to +70°C 8-Pin PDIP
MIC4422ACT MIC4422AZT Non-Inverting 0° to +70°C 5-Pin TO-220
* Special order. Contact factory.
Pin Configur ation
1
2
3
4
8
7
6
5
VS
OUT
OUT
GND
VS
IN
NC
GND
TAB
5 OUT
4 GND
3VS
2 GND
1IN
8-Pin PDIP (N)
8-Pin SOIC (M)
5-Pin TO-220 (T)
Pin Description
Pin Number
DIP, SOIC Pin Number
TO-220-5
Pin Name Pin Name
2 1 IN Control Input.
4, 5 2, 4 GND Ground: Duplicate pins must be externally connected
together.
1, 8 3, TAB VS Supply Input: Duplicate pins must be externally connected
together.
6, 7 5 OUT Output: Duplicate pins must be externally connected
together.
3 — NC Not connected.
Micrel, Inc. MIC4421A/4422A
June 2007
3 M9999-062707
Absolute Maximum Ratings(1)
Supply Voltage (V
S
)......................................................+20V
Control Input Voltage (V
IN
). ............. V
S
+ 0.3V to GND – 5V
Control Input Current (V
IN
> V
S
). .................................50mA
Power Dissipation, T
A
< +25°C
(4)
PDIP (θ
JA
) ........................................................1478mW
SOIC (θ
JA
) ..........................................................767mW
TO-220 (θ
JA
)........................................................1756W
Lead Temperature (soldering, #sec.)......................... 300°C
Storage Temperature (T
s
) .........................–65°C to +150°C
ESD Rating
(3)
.................................................................. 2kV
Operating Ratings(2)
Supply Voltage (V
S
)....................................... +4.5V to +18V
Ambient Temperature (T
A
)
A Version ............................................ –55°C to +125°C
B Version .............................................. –40°C to +85°C
C Version .................................................. 0°C to +70°C
Junction Temperature (T
J
) ......................................... 150°C
Package Thermal Resistance
(4)
PDIP (θ
JA
) .......................................................84.6°C/W
SOIC (θ
JA
).....................................................163.0°C/W
TO-220 (θ
JA
)....................................................71.2°C/W
PDIP (θ
JC
) .......................................................41.2°C/W
SOIC (θ
JC
).......................................................38.8°C/W
TO-220 (θ
JC
) .....................................................6.5°C/W
Electrical Characteristics
T
A
= 25°C with 4.5V V
S
18V, bold values indicate –55°C< T
A
< +125°C, unless noted.
Symbol Parameter Condition Min Typ Max Units
Power Supply
V
S
Operating Input Voltage 4.5 18 V
High Output Quiescent Current V
IN
= 3V (MIC4422A), V
IN
= 0 (MIC4421A) 0.5 1.5
3
mA
mA
I
S
Low Output Quiescent Current V
IN
= 0V (MIC4422A), V
IN
= 3V (MIC4421A) 50 150
200
µA
µA
Input
V
IH
Logic 1 Input Voltage See Figure 3 3.0 2.1 V
V
IL
Logic 0 Input Voltage See Figure 3 1.5 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 µA
Output
V
OH
High Output Voltage See Figure 1 V
S
+.025 V
V
OL
Low Output Voltage See Figure 1 0.025 V
Output Resistance,
Output High
I
OUT
= 10mA, V
S
= 18V 0.6 1.0
3.6
R
O
Output Resistance,
Output Low
I
OUT
= 10mA, V
S
= 18V 0.8 1.7
2.7
I
PK
Peak Output Current V
S
= 18V (See Figure 8) 9 A
I
DC
Continuous Output Current 2 A
I
R
Latch-Up Protection
Withstand Reverse Current
Duty Cycle 2%
t 300µs, Note 5
>1500 mA
Switching Time (Note 5)
t
R
Rise Time Test Figure 1, C
L
= 10,000pF 20 75
120
ns
ns
t
F
Fall Time Test Figure 1, C
L
= 10,000pF 24 75
120
ns
ns
t
D1
Delay Time Test Figure 1 15 68
80
ns
ns
Micrel, Inc. MIC4421A/4422A
June 2007
4 M9999-062707
Symbol Parameter Condition Min Typ Max Units
Switching Time (Note 5) continued
t
D2
Delay Time Test Figure 1 35 60
80
ns
ns
t
PW
Minimum Input Pulse Width See Figure 1 and Figure 2. 50 ns
f
max
Maximum Input Frequency See Figure 1 and Figure 2. 1 MHz
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Minimum footprint.
5. Guaranteed by design.
Test Circuit
MIC4421A
10,000pF
= 18V
0.1µF 4.7µF
0.1µF
V
IN
V
OUT
V
S
MIC4422A
10,000pF
= 18V
0.1µF 4.7µ
F
0.1µF
V
IN
V
OUT
V
S
t
D1
90%
10%
t
F
10%
0V
5V
t
D2
t
R
V
S
OUTPUT
INPUT 90%
0V
t
PW
50ns
2.5V
t
PW
90%
10%
t
R
10%
0V
5V
t
F
V
S
OUTPUT
INPUT 90%
0V
t
PW
50ns
t
D1
t
D2
t
PW
2.5V
Figure 1. Inverting Driver Switching Time Figure 2. Non-Inverting Dri ver Switching Time
Control Input Behavior
Logic 1
Logic 0
V
IH
V
IH
V
IL
V
IL
0.8V
1.5V0V 2.1V V
S
3V
Figure 3. Input Hysteresis
Micrel, Inc. MIC4421A/4422A
June 2007
5 M9999-062707
Typical Characteristics
Micrel, Inc. MIC4421A/4422A
June 2007
6 M9999-062707
Typical Characteristics (continued)
Micrel, Inc. MIC4421A/4422A
June 2007
7 M9999-062707
Functional Diagram
IN
OU
T
MIC4421A
INVERTING
MIC4422A
NONINVERTING
0.1mA
0.3mA
Q1
VS
GND
Q2 Q3
Q4
Figure 4. MIC4421A/22 A Block Diagram
Functional Description
Refer to the functional diagram.
The MIC4422A is a non-inverting driver. A logic high on
the IN produces gate drive output. The MIC4421A is an
inverting driver. A logic low on the IN produces gate
drive output. The output is used to turn on an external N-
channel MOSFET.
Supply
V
S
(supply) is rated for +4.5V to +18V. External
capacitors are recommended to decouple noise.
Input
IN (control) is a TTL-compatible input. IN must be forced
high or low by an external signal. A floating input will
cause unpredictable operation.
A high input turns on Q1, which sinks the output of the
0.1mA and the 0.3mA current source, forcing the input of
the first inverter low.
Hysteresis
The control threshold voltage, when IN is rising, is
slightly higher than the control threshold voltage when
CTL is falling.
When IN is low, Q2 is on, which applies the additional
0.3mA current source to Q1. Forcing IN high turns on Q1
which must sink 0.4mA from the two current sources.
The higher current through Q1 causes a larger drain-to-
source voltage drop across Q1. A slightly higher control
voltage is required to pull the input of the first inverter
down to its threshold.
Q2 turns off after the first inverter output goes high. This
reduces the current through Q1 to 0.1mA. The lower
current reduces the drain-to-source voltage drop across
Q1. A slightly lower control voltage will pull the input of
the first inverter up to its threshold.
Drivers
The second (optional) inverter permits the driver to be
manufactured in inverting and non-inverting versions.
The last inverter functions as a driver for the output
MOSFETs Q3 and Q4.
Output
OUT is designed to drive a capacitive load. V
OUT
(output
voltage) is either approximately the supply voltage or
approximately ground, depending on the logic state
applied to IN.
If IN is high, and V
S
(supply) drops to zero, the output
will be floating (unpredictable).
Micrel, Inc. MIC4421A/4422A
June 2007
8 M9999-062707
Application 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 MIC4421A/4422A 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.
1µF
MIC4421A
Drive
Logic
V
S
V
S
V
S
MIC4422A
V
S
1µF
Ø1 Drive Signal
Conduction Angle
Control 0°C to 180°C
Conduction Angle
Control 180°C to 360°
C
Ø1
Ø2
Ø3
Phase 1 of 3 Phase Motor
Driver Using MIC4421A/22A
Figure 5. Direct Motor Drive
To guarantee low supply impedance over a wide
frequency range, a parallel capacitor combination is
recommended for supply bypassing. Low inductance
ceramic disk capacitor swith short lead lengths (< 0.5
inch) should be used. A 1µF low ESR film capacitor in
parallel with two 0.1µF low ESR ceramic capacitors,
(such as AVX RAM Guard
®
), provides adequate
bypassing. Connect one ceramic capacitor directly
between pins 1 and 4. Connect the second ceramic
capacitor directly between pins 8 and 5.
Grounding
The high current capability of the MIC4421A/4422A
demands careful PC board layout for best performance.
Since the MIC4421A is an inverting driver, any ground
lead impedance will appear as negative feedback which
can degrade switching speed. Feedback is especially
noticeable with slow-rise time inputs. The MIC4421A
input structure includes about 600mV of hysteresis to
ensure clean transitions and freedom from oscillation,
but attention to layout is still recommended.
Figure 7 shows the feedback effect in detail. As the
MIC4421A 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 MIC4421A
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 MIC4421A
GND pins will ensure full logic drive to the input and
ensure fast output switching. Both of the MIC4421A
GND pins should, however, still be connected to power
ground.
MIC4422A
V
IN
+15V
0.1µF
50V
United Chemcon SXE
0.1µF
WIMA
MKS2
1µF
WIMA
MKS2
BYV 10
(x2)
100µF
50V
500µF
50V
1N4448
(x2)
30
29
28
27
26
25
mA
VOLTS
Output
V
oltage
vs. Load Current
0 50 100 150 200 250 300 350
Figure 6. Self Contained Voltage Doubler
Micrel, Inc. MIC4421A/4422A
June 2007
9 M9999-062707
Input Stage
The input voltage level of the MIC4421A changes the
quiescent supply current. The N-Channel MOSFET input
stage transistor drives a 320µA current source load. With
a logic “1” input, the quiescent supply current is typically
500µA. Logic “0” input level signals reduce quiescent
current to 80µA typical.
The MIC4421A/4422A input is designed to provide
600mV of hysteresis. This provides clean transitions,
reduces noise sensitivity, and minimizes output stage
current spiking when changing states. Input voltage
threshold level is approximately 1.5V, making the device
TTL compatible over the full temperature and operating
supply voltage ranges. Input current is less than ±10µA.
The MIC4421A can be directly driven by the TL494,
SG1526/1527, SG1524, TSC170, MIC38C42, and
similar switch mode power supply integrated circuits. By
off loading the power-driving duties to the MIC4421A/
4422A, 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 (6.4mARMS) with the input.
No damage will occur to MIC4421A/4422A 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
MIC4421A/4422A on the other hand, can source or sink
several amperes and drive large capacitive loads at high
frequency. The package power 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.
MIC4421A
V
IN
+18V
0.1µF
1
86, 7
5
4
0.1µF 2500pF
Polycarbonate
TEK Current
Probe 6302
Logic
Ground
Power
Ground
300mV
6 Amps
PC Trace
+18V
0V
+5.0V
0V
WIMA
MKS-2
1µF
Figure 7. Switching Time Due to Negati ve Feedback
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 dissipation 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 84.6°C/W. In a 25°C
ambient, then, using a maximum junction temperature of
150°C, this package will dissipate 1478mW.
Accurate power dissipation numbers can be obtained by
summing the three sources of power dissipation in the
device:
• Load Power Dissipation (PL)
• Quiescent power dissipation (PQ)
• Transition power dissipation (PT)
Calculation of load power dissipation differs depending
on whether the load is capacitive, resistive or inductive.
Resistive Load Po wer 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).
Micrel, Inc. MIC4421A/4422A
June 2007
10 M9999-062707
Table 1. MIC4421 A Maximum Operating Frequency
V
S
Max Frequency
18V 220kHz
15V 300kHz
10V 640kHz
5V 2MHz
Conditions:
1. θ
JA
= 150°C/W
2. T
A
= 25°C
3. C
L
= 10,000pF
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:
PL = f C (VS)2
where:
f = Operating Frequency
C = Load Capacitance
VS = 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 (PQ, 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
Transition Po wer 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
(A•s)
where (A•s) 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.
Micrel, Inc. MIC4421A/4422A
June 2007
11 M9999-062707
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 repetitions 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.
MIC4421A
+18V
0.1µF
1
8
6, 7
5
4
0.1µF 10,000pF
Polycarbonate
TEK Current
Probe 6302
+18V
0V
+5.0V
0V
WIMA
MK22
1µF
Figure 8. Peak Output Current Test Circuit
Micrel, Inc. MIC4421A/4422A
June 2007
12 M9999-062707
Package Information
0.380 (9.65)
0.370 (9.40) 0.135 (3.43)
0.125 (3.18)
PIN 1
DIMENSIONS:
INCH (MM)
0.018 (0.57)
0.100 (2.54)
0.013 (0.33
0
0.010 (0.25
4
0.300 (7.62)
0.255 (6.48)
0.245 (6.22)
0.380 (9.65)
0.320 (8.13)
0.0375
(
0.952
)
0.130 (3.30)
8-Pin Plastic DIP (N)
8-Pin SOIC (M)
Micrel, Inc. MIC4421A/4422A
June 2007
13 M9999-062707
5-Pin TO-220 (T)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2002 Micrel, Incorporated.
