MIC4120/4129
Micrel
December 2004
1
M9999-123104
MIC4120/4129
6A-Peak Low-Side MOSFET Driver
Bipolar/CMOS/DMOS Process
General Description
MIC4120 and MIC4129 MOSFET drivers are tough, effi-
cient, and easy to use. The MIC4129 is an inverting driver,
while the MIC4120 is a non-inverting driver. The MIC4120
and MIC4129 are improved versions of the MIC4420 and
MIC4429.
They are capable of 6A (peak) output and can drive the
largest MOSFETs with an improved safe operating margin.
The MIC4120/4129 accept 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.
MIC4120/4129 drivers can replace three or more discrete
components, reducing PCB area requirements, simplifying
product design, and reducing assembly cost.
Modern BiCMOS/DMOS construction guarantees freedom
from latch-up. The rail-to-rail swing capability insures ad-
equate gate voltage to the MOSFET during power up/down
sequencing.
Features
CMOS Construction
Latch-Up Protected: Will Withstand >500mA
Reverse Output Current
Logic Input Withstands Negative Swing of Up to 5V
Matched Rise and Fall Times ................................ 25ns
High Peak Output Current ............................... 6A Peak
Wide Operating Range ............................... 4.5V to 20V
High Capacitive Load Drive ............................10,000pF
Low Delay Time .............................................. 55ns Typ
Logic High Input for Any Voltage From 2.4V to V
S
Low Equivalent Input Capacitance (typ) ..................6pF
Low Supply Current ...............450A With Logic 1 Input
Low Output Impedance ......................................... 2.5
Output Voltage Swing Within 25mV of Ground or V
S
Exposed backside pad packaging reduces heat
- ePAD SOIC-8L (
JA
= 58C/W
)
- ePAD MSOP-8L
(
JA
= 60C/W
)
- 3mm x 3mm MFLTM-8L
(
JA
= 60C/W
)
Applications
Switch Mode Power Supplies
Motor Controls
Pulse Transformer Driver
Class-D Switching Amplifiers
Functional Diagram
IN
OUT
MIC4129
INVERTING
MIC4120
NONINVERTING
0.1mA
0.4mA
2k
V
S
GND
Micrel, Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 http://www.micrel.com
MIC4120/4129
Micrel
M9999-123104
2
December 2004
Pin Configurations
1
2
3
4
8
7
6
5
V S
OUT
OUT
GND
V S
IN
NC
GND
Ordering Information
Part Number
Package
Configuration
Lead Finish
MIC4120YME
EPAD 8-Lead SOIC
Non-Inverting
Pb-Free
MIC4120YMME
EPAD 8-Lead MSOP
Non-Inverting
Pb-Free
MIC4120YML
8-Lead MLF
Non-Inverting
Pb-Free
MIC4129YME
EPAD 8-Lead SOIC
Inverting
Pb-Free
MIC4129YMME
EPAD 8-Lead MSOP
Inverting
Pb-Free
MIC4129YML
8-Lead MLF
Inverting
Pb-Free
Pin Description
Pin Number
DIP, SOIC, MSOP
Pin Name
Pin Function
2
IN
Control Input
4, 5
GND
Ground: Duplicate pins must be externally connected together
1, 8
VS
Supply Input: Duplicate pins must be externally connected together
6, 7
OUT
Output: Duplicate pins must be externally connected together
3
NC
Not connected
EP
GND
Ground: Backside
MIC4120/4129
Micrel
December 2004
3
M9999-123104
Electrical Characteristics:
(T
A
= 25C with 4.5V V
S
20V unless otherwise specified. Note 4.)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
INPUT
V
IH
Logic 1 Input Voltage
2.4
1.9
V
V
IL
Logic 0 Input Voltage
1.5
0.8
V
V
IN
Input Voltage Range
5
1.4
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
0.025
V
V
OL
Low Output Voltage
See Figure 1
0.025
V
R
O
Output Resistance,
I
OUT
= 10 mA, V
S
= 20 V
1.4
5
Output Low
R
O
Output Resistance,
I
OUT
= 10 mA, V
S
= 20 V
1.5
5
Output High
I
PK
Peak Output Current
V
S
= 18 V (See Figure 6)
6
A
I
R
Latch-Up Protection
500
mA
Withstand Reverse Current
SWITCHING TIME (Note 3)
t
R
Rise Time
Test Figure 1, C
L
= 2500 pF
12
30
ns
t
F
Fall Time
Test Figure 1, C
L
= 2500 pF
13
30
ns
t
D1
Delay Time
Test Figure 1
45
100
ns
t
D2
Delay Time
Test Figure 1
50
100
ns
POWER SUPPLY
I
S
Power Supply Current
V
IN
= 3 V
0.45
3
mA
V
IN
= 0 V
80
400
A
V
S
Operating Input Voltage
4.5
20
V
Notes:
1. Functional operation above the absolute maximum stress ratings is not implied.
2. Static-sensitive device. Store only in conductive containers. Handling personnel and equipment should be grounded to prevent
damage from static discharge.
3. Switching times guaranteed by design.
4. Specification for packaged product only.
Absolute Maximum Ratings
(Notes 1, 2 and
3)
Supply Voltage ...........................................................24V
Input Voltage ...............................V
S
+ 0.3V to GND 5V
Input Current (V
IN
> V
S
) ..........................................50mA
Storage Temperature ............................. 65C to +150C
Lead Temperature (10 sec.) ................................... 300C
Operating Ratings
Supply Voltage .............................................. 4.5V to 20V
Junction Temperature ............................ 40C to +125C
Package Thermal Resistance
3x3 MLFTM (
JA
) ...............................................60C/W
EPAD MSOP-8L (
JA
) .......................................60C/W
EPAD SOIC-8L (
JA
) .........................................58C/W
MIC4120/4129
Micrel
M9999-123104
4
December 2004
Figure 1. Inverting Driver Switching Time
IN
MIC4129
OUT
2500pF
V
S
= 20V
0.1F
1.0F
0.1F
IN
MIC4120
OUT
2500pF
V
S
= 20V
0.1F
1.0F
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
Test Circuits
MIC4120/4129
Micrel
December 2004
5
M9999-123104
Typical Characteristics
0
10
20
30
40
50
60
5
10
15
20
RISE TIME (ns)
INPUT VOLTAGE (V)
R is e T ime
4700pF
10000pF
2200pF
0
10
20
30
40
50
60
5
10
15
20
FALL TIME (ns)
INPUT VOLTAGE (V)
F all T ime
4700pF
10000pF
2200pF
0
10
20
30
40
50
60
5
10
15
20
DELAY TIME (ns)
INPUT VOLTAGE (V)
Delay T ime
vs . Input V oltage
td1
td2
0
0.5
1.0
1.5
2.0
2.5
3.0
5
10
15
20
RESISTANCE (
)
SUPPLY VOLTAGE (V)
Output R es is tance
vs . S upply V oltage
Output Low
Output High
MIC4120/4129
Micrel
M9999-123104
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December 2004
Applications Information
Supply Bypassing
Charging and discharging large capacitive loads quickly
requires large currents. For example, charging a 2500pF
load to 18V in 25ns requires a 1.8 A current from the device
power supply.
The MIC4120/4129 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.
To guarantee low supply impedance over a wide frequency
range, a parallel capacitor combination is recommended
for supply bypassing. Low inductance ceramic capacitors
should be used. A 1F low ESR film capacitor in parallel with
two 0.1 F low ESR ceramic capacitors provide 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 MIC4120/4129 demands
careful PC board layout for best performance Since the
MIC4129 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.
Figure 3 shows the feedback effect in detail. As the MIC4129
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 MIC4129 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. Con-
necting the logic ground directly to the MIC4129 GND pins
will ensure full logic drive to the input and ensure fast output
switching. Both of the MIC4129 GND pins should, however,
still be connected to power ground.
The E-Pad and MLF packages have an exposed pad under
the package. It's important for good thermal performance that
this pad is connected to a ground plane.
MIC4120/4129
Micrel
December 2004
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M9999-123104
Table 1: MIC4129 Maximum
Operating Frequency
V
S
Max Frequency
20V
1MHz
15V
1.5MHz
10V
3.5MHz
Conditions:
T
A
= 25C, 3. C
L
= 2500pF
Input Stage
The input voltage level of the 4129 changes the quiescent
supply current. The N channel MOSFET input stage transistor
drives a 450A current source load. With a logic "1" input, the
maximum quiescent supply current is 450A. Logic "0" input
level signals reduce quiescent current to 55A maximum.
The MIC4120/4129 input is designed to provide 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 4 .5V to 20V
operating supply voltage range. Input current is less than
10A over this range.
The MIC4129 can be directly driven by the MIC9130,
MIC3808, MIC38HC42 and similar switch mode power
supply integrated circuits. By offloading the power-driving
duties to the MIC4120/4129, 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 propagation delay for T
D2
will increase to as much as 400ns at room temperature. The
input currents can be as high as 30mA p-p (6.4mA
RMS
) with
the input, 6 V greater than the supply voltage. No damage
will occur to MIC4120/4129 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. Care should be
taken so that the input does not go more than 5 volts below
the negative rail.
Power Dissipation
CMOS circuits usually permit the user to ignore power dis-
sipation. 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 MIC4120/4129 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.
The supply current vs frequency and supply current vs capaci-
tive load characteristic curves aid in determining power dissi-
pation calculations. Table 1 lists the maximum safe operating
frequency for several power supply voltages when driving a
2500pF 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 ther-
mal resistance of the 8-pin EPAD MSOP package, from the
data sheet, is 60C/W. In a 25C ambient, then, using a
maximum junction temperature of 150C, this package will
dissipate 2W.
Accurate power dissipation numbers can be obtained by sum-
ming 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 3. Switching Time Degradation Due to
Negative Feedback
MIC4121
1
8
6, 7
5
4
+18 V
0.1 F
0.1F
T E K C U R R E N T
PROBE 6302
2,500 pF
PO LY C A R B O N A T E
5.0V
0 V
18 V
0 V
WIMA
MK22
1 F
LOGIC
GROUND
POWER
GROUND
6 AMPS
PC TRACE RESISTANCE = 0.05
MIC4120/4129
Micrel
M9999-123104
8
December 2004
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 Power Dissipation
Transition power is dissipated in the driver each time its out-
put 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 curves.
Total power (P
D
) then, as previously described is:
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 shown by the "Typical Characteristic Curve :
Crossover Area vs. Supply Voltage and is in am-
pere-seconds. 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.
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 on 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 induc-
tor 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 2.0mA.
Quiescent power can therefore be found from:
P
Q
= V
S
[D I
H
+ (1-D) I
L
]
where:
MIC4120/4129
Micrel
December 2004
9
M9999-123104
Figure 4. Peak Output Current Test Circuit
MIC4129
1
8
6, 7
5
4
+18 V
0.1F
0.1F
T E K C U R R E N T
PROBE 6302
10,000 pF
PO LY C A R B O N A T E
5.0V
0 V
18 V
0 V
WIMA
MK22
1 F
2
MIC4120/4129
Micrel
M9999-123104
10
December 2004
Package Information
8-Pin 3x3 MLF (ML)
8-Pin Exposed Pad SOIC (ME)
MIC4120/4129
Micrel
December 2004
11
M9999-123104
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
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.
2004 Micrel Incorporated
8-Pin Exposed Pad MSOP (MME)
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