MIC5060 - Micrel

MIC5060
High-or Low-Side MOSFET Driver
General Description
Features
The MIC5060 MOSFET driver is designed for gate control
of N-Channel, enhancement-mode, and power MOSFETs
used as high-side or low-side switches. The MIC5060 can
sustain an on-state output indefinitely.
The MIC5060 operates from a 2.75V to 30V supply. In
high-side configurations, the driver can control MOSFETs
that switch loads of up to 30V. In low-side configurations,
with separate supplies, the maximum switched voltage is
limited only by the MOSFET.
The MIC5060 has a non-inverting, TTL-compatible control
input.
The MIC5060 features an internal charge pump that can
sustain a gate voltage greater than the available supply
voltage. The driver is capable of turning on a logic-level
MOSFET from a 2.75V supply or a standard MOSFET
from a 5V supply. The gate-to-source output voltage is
internally limited to approximately 15V.
The MIC5060 is protected against automotive load dump,
reversed battery, and inductive load spikes of –20V.
The driver’s overvoltage shutdown feature turns off the
external MOSFET at approximately 35V to protect the load
against power supply excursions.
The MIC5060 is available in 3mm x 3mm MLF® package.
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
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2.75V to 30V operation
100µA maximum supply current (5V supply)
15µA typical off-state current
Internal charge pump
TTL-compatible input
Withstands 60V transient (load dump)
Reverse battery protected to –20V
Inductive spike protected to –20V
Overvoltage shutdown at 35V
Internal 15V gate protection
Minimum external parts
Operates in high-side or low-side configurations
1µA control input pull-off
Available in 8-pin 3mm x 3mm MLF® package
Applications
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Notebook Battery safety switches
UMPC and Web Tablet Battery protection
Battery-powered computer power management
General MOSFET switch applications
Power bus switching
_________________________________________________________________________________________________________________________
Typical Application
3V “Sleep-Mode” Switch with a Logic-Level MOSFET
MLF is a registered trademark of Amkor Technology, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
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Micrel, Inc.
MIC5060
Ordering Information(1, 2)
Part Number
Marking Code
Temperature Range
Configuration
Package
MIC5060YML
MIC5060
-40°C to +85°C
Non-Inverting
8-pin 3mm x 3mm MLF®
Note:
1. Pin 1 identifier symbol is “•”.
®
2. MLF is a Green RoHS-compliant package. Lead finish is NiPdAu. Mold compound is Halogen free.
Pin Configuration
8-Pin (3mm x 3mm) MLF® (ML)
Top View
Pin Description
Pin Number
Pin Name
1
V+
2
Input
Turns on power MOSFET when taken above (or below) threshold (1.0V typical). Pin 2
requires ~ 1µA to switch.
3
Source
Connects to source lead of power MOSFET and is the return for the gate clamp zener.
Pin 3 can safely swing to –20V when turning off inductive loads.
4
Ground
5
Gate
6, 7, 8
NC
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Pin Function
Supply. Must be decoupled to isolate from large transients caused by the power MOSFET
drain. 10µF is recommended close to pins 1 and 4.
Ground.
Drives and clamps the gate of the power MOSFET.
Not internally connected.
2
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MIC5060
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage ................................................. –20V to 60V
Input Voltage .......................................... –20V to V(+)+0.3V
Source Voltage................................................... –20V to V+
Source Current ............................................................50mA
Gate Voltage .................................................... –20V to 50V
Lead Temperature (Soldering, 10 sec) ...................... 260°C
Junction Temperature ................................................ 150°C
Storage Temperature (Ts)............................-65°C to 150°C
Ambient Temperature: ................................ –40°C to +85°C
Supply Voltage (V+) ........................................ 2.75V to 30V
Junction Thermal Resistance
3mm x 3mm MLF® (θJA).....................................60°C/W
Electrical Characteristics
TJ = TA = -40°C to +85°C unless otherwise specified.
Parameter
Condition
Supply Current
V+ = 30V
Typ.
Max.
Units
VIN De-Asserted, Note 3
10
25
µA
VIN Asserted, Note 3
5.0
10
mA
VIN De-Asserted, Note 3
10
25
µA
VIN Asserted, Note 3
60
100
µA
VIN De-Asserted, Note 3
10
25
µA
VIN Asserted, Note 3
25
35
µA
VINPUT=V+
TA = 25°C
V+ On Threshold
2.6
2.75
2.75V ≤ V+ ≤ 30V
TA = 25°C
Digital Low Level
Digital High Level
2.0
2.75V ≤ V+ ≤ 30V
VIN Low
-2.0
V+ = 5V
V+ = 3V
Minimum Input Voltage
Logic Input Voltage Threshold VIN
Logic Input Current MIC5060
Min.
V+ Off Threshold
2.4
2.6
0.8
VIN High
0
1.0
V
V
µA
2.0
µA
17
V
15
17
V
Gate Enhancement
VGATE – VSUPPLY
3.0V ≤ V+ ≤ 30V
VIN Asserted
3.0
Zener Clamp
VGATE – VSOURCE
8.0V ≤ V+ ≤ 30V
VIN Asserted
13
Gate Turn-on Time, tON
Note 4
V+ = 4.5V
CL = 1000pF
VIN switched on, measure time
for VGATE to reach V+ + 4V
2.5
8.0
ms
V+ = 12V
CL = 1000pF
As above, measure time for
VGATE to reach V+ + 4V
90
140
µs
V+ = 4.5V
CL = 1000pF
VIN switched off, measure time
for VGATE to reach 1V
6.0
30
µs
V+ = 12V
CL = 1000pF
As above, measure time for
VGATE to reach 1V
6.0
30
µs
37
41
V
Gate Turn-off Time, tOFF
Note 4
Overvoltage Shutdown Threshold
35
Notes:
1.
Exceeding the absolute maximum rating may damage the device.
2.
The device is not guaranteed to function outside its operating rating.
3.
“Asserted” refers to a logic high on the MIC5060.
4.
Test conditions reflect worst-case high-side driver performance. Low-side and bootstrapped topologies are significantly faster—see Applications
Information.
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MIC5060
Typical Characteristics
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MIC5060
Typical Characteristics (continued)
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MIC5060
Block Diagram
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MIC5060
affected, but also it is possible to overstress various
components, especially electrolytic capacitors, with
possibly catastrophic results. A 10µF supply bypass
capacitor at the chip is recommended. Residual
resistances: Resistances in circuit connections may also
cause confusing results. For example, a circuit may
employ a 50mΩ power MOSFET for low voltage drop, but
unless careful construction techniques are used, one could
easily add 50mΩ to 100mΩ resistance. Do not use a
socket for the MOSFET. If the MOSFET is a TO-220 type
package, make high current connections to the drain tab.
Wiring losses have a profound effect on high-current
circuits. A floating milliohmeter can identify connections
that are contributing excess drop under load.
Application Information
Minimum V+ Operation
For V+ voltages less than 2.4V, the input comparator that
determines the output of the gate overrides INPUT and
forces the gate-source voltage low. This input comparator
is fully operational when the V+ voltage is equal to, or
greater than, 2.75V. For more detail, refer to the typical
characteristics graph that demonstrates VGATE-SOURCE vs.
V+.
Functional Description
The internal functions of the MIC5060 is controlled via a
logic block (refer to block diagram) connected to the
control input (pin 2). When the input is off (low), all
functions are turned off, and the gate of the external power
MOSFET is held low via two N-Channel switches. This
results in a very low standby current, 15µA typical, which is
necessary to power an internal bandgap.
When the input is driven to the “ON” state, the N-Channel
switches are turned off, the charge pump is turned on, and
the P-Channel switch between the charge pump and the
gate turns on, allowing the gate of the power FET to be
charged. The op amp and internal zener form an active
regulator which shuts off the charge pump when the gate
voltage is high enough.
The charge pump incorporates a 100kHz oscillator and onchip pump capacitors capable of charging a 1000pF load
in 90µs typical. In addition to providing active regulation,
the internal 15V zener is included to prevent exceeding the
VGS rating of the power MOSFET at high supply voltages.
The MIC5060 device has been improved for greater
ruggedness and durability. All pins can withstand being
pulled 20V below ground without sustaining damage, and
the supply pin can withstand an overvoltage transient of
60V for 1s. An overvoltage shutdown has also been
included, which turns off the device when the supply
exceeds 35V.
Low Voltage Testing
As the MIC5060 has relatively high output impedances, a
normal oscilloscope probe will load the device. This is
especially pronounced at low voltage operation. It is
recommended that a FET probe or unity gain buffer be
used for all testing.
Circuit Topologies
The MIC5060 is well suited for use with standard power
MOSFETs in both low and high side driver configurations.
In addition, the lowered supply voltage requirements of
these devices make them ideal for use with logic level
FETs in high side applications with a supply voltage of 3V
to 4V. (If higher supply voltages [>4V] are used with logic
level FETs, an external zener clamp must be supplied to
ensure that the maximum VGS rating of the logic FET [10V]
is not exceeded.) In addition, a standard IGBT can be driven
using these devices.
Choice of one topology over another is usually based on
speed vs. safety. The fastest topology is the low side
driver, however, it is not usually considered as safe as
high side driving as it is easier to accidentally short a load
to ground than to VCC. The slowest, but safest topology is
the high side driver; with speed being inversely
proportional to supply voltage. It is the preferred topology
for most military and automotive applications. Speed can
be improved considerably by bootstrapping from the
supply.
All topologies implemented using these devices are well
suited to driving inductive loads, as either the gate or the
source pin can be pulled 20V below ground with no effect.
External clamp diodes are unnecessary, except for the
case in which a transient may exceed the overvoltage trip
point.
Construction Hints
High current pulse circuits demand equipment and
assembly techniques that are more stringent than normal,
low current lab practices. The following are the sources of
pitfalls most often encountered during prototyping:
Supplies: Many bench power supplies have poor transient
response. Circuits that are being pulse tested, or those
that operate by pulse-width modulation will produce
strange results when used with a supply that has poor
ripple rejection, or a peaked transient response. Always
monitor the power supply voltage that appears at the drain
of a high side driver (or the supply side of the load for a
low side driver) with an oscilloscope. It is not uncommon to
find bench power supplies in the 1kW class that overshoot
or undershoot by as much as 50% when pulse loaded. Not
only will the load current and voltage measurements be
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MIC5060
current in the “off” state is only a small leakage, the 100nF
bypass capacitor tends to remain charged for several
seconds after the MIC5060 is turned off. Faster speeds
can be obtained at the expense of supply voltage (the
overvoltage shutdown will turn the part off when the
bootstrapping action pulls the supply pin above 35V) by
using a larger capacitor at the junction of the two 1N4001
diodes. In a PWM application (this circuit can be used for
either PWM’ed or continuously energized loads), the chip
supply is sustained at a higher potential than the system
supply, which improves switching time.
Figure 1. 3V “Sleep-Mode” Switch
with a Logic-Level MOSFET
High Side Driver
The high side topology shown in Figure 1 is an
implementation of a “sleep-mode” switch for a laptop or
notebook computer, which uses a logic level FET. A
standard power FET can easily be substituted when
supply voltages above 4V are required.
Figure 3. Bootstrapped High-Side Driver
High Side Driver with Current Sense
Although no current sense function is included on the
MIC5060, a simple current sense function can be realized
via the addition of one more active component; an
LM301A op amp used as a comparator. The positive rail of
the op amp is tied to V+, and the negative rail is tied to
ground. This op amp was chosen as it can withstand
having input transients that swing below the negative rail,
and has common mode range almost to the positive rail.
The inverting side of this comparator is tied to a voltage
divider, which sets the voltage to V+ – VTRIP. The non
inverting side is tied to the node between the drain of the
FET and the sense resistor. If the overcurrent trip point is
not exceeded, this node will always be pulled above V+ –
VTRIP, and the output of the comparator will be high which
feeds the control input of the MIC5060. Once the
overcurrent trip point has been reached, the comparator
will go low, which shuts off the MIC5060. When the short is
removed, feedback to the input pin insures that the
MIC5060 will turn back on. This output can also be level
shifted and sent to an I/O port of a microcontroller for
intelligent control.
Figure 2. Low Side Driver
Low Side Driver
A key advantage of this topology, as previously mentioned,
is speed. The MOSFET gate is driven to near supply
immediately when the MIC5060 is turned on. Typical
circuits reach full enhancement in 50µs or less with a 15V
supply.
Bootstrapped High Side Driver
The turn-on time of a high side driver can be improved to
faster than 40µs by bootstrapping the supply with the
MOSFET source. The Schottky barrier diode prevents the
supply pin from dropping more than 200mV below the
drain supply and improves turn-on time. Since the supply
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MIC5060
Current Shunts (RS). Low valued resistors are necessary
for use at RS. Resistors are available with values ranging
from 1 mΩ to 50mΩ, at 2 to 10W. If a precise overcurrent
trip point is not necessary, then a non-precision resistor or
even a measured PCB trace can serve as RS. The major
cause of drift in resistor values with such resistors is
temperature coefficient; the designer should be aware that
a linear, 500ppm/°C change will contribute as much as
10% shift in the overcurrent trip point. If this is not
acceptable, a power resistor designed for current shunt
service (drifts less than 100ppm/°C), or a Kelvin-sensed
resistor may be used.†
Figure 4. High Side Driver with Overcurrent Shutdown
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MIC5060
Typical Applications
Variable Supply Low Side Driver for Motor Speed
Control
The internal regulation in the MIC5060 allows a steady
gate enhancement to be supplied while the MIC5060
supply varies from 5V to 30V, without damaging the
internal gate to source zener clamp. This allows the
speed of the DC motor shown to be varied by varying
the supply voltage.
Figure 6. Solenoid Valve Driver
Incandescent/Halogen Lamp Driver
The combination of an MIC5060 and a power FET
makes an effective driver for a standard incandescent or
halogen lamp load. Such loads often have high inrush
currents, as the resistance of a cold filament is less than
one-tenth as much as when it is hot. Power MOSFETs
are well suited to this application as they have wider safe
operating areas than do power bipolar transistors. It is
important to check the SOA curve on the data sheet of
the power FET to be used against the estimated or
measured inrush current of the lamp in question prior to
prototyping to prevent “explosive” results.
Figure 5. DC Motor Speed Control/Driver
Solenoid Valve Driver
High power solenoid valves are used in many industrial
applications requiring the timed dispensing of chemicals
or gases. When the solenoid is activated, the valve
opens (or closes), releasing (or stopping) fluid flow. A
solenoid valve, like all inductive loads, has a
considerable “kickback” voltage when turned off, as
current cannot change instantaneously through an
inductor. In most applications, it is acceptable to allow
this voltage to momentarily turn the MOSFET back on as
a way of dissipating the inductor’s current. However, if
this occurs when driving a solenoid valve with a fast
switching speed, chemicals or gases may be
inadvertently be dispensed at the wrong time with
possibly disastrous consequences. Also, too large of a
kickback voltage (as is found in larger solenoids) can
damage the MIC5060 or the power FET by forcing the
Source node below ground (the MIC5060 can be driven
up to 20V below ground before this happens). A catch
diode has been included in this design to provide an
alternate route for the inductive kickback current to flow.
The 5kΩ resistor in series with this diode has been
included to set the recovery time of the solenoid valve.
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Figure 7. Halogen Lamp Driver
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MIC5060
Relay Driver
Some power relay applications require the use of a
separate switch or drive control, such as in the case of
microprocessor control of banks of relays where a logic
level control signal is used, or for drive of relays with
high power requirements. The combination of an
MIC5060 and a power FET also provides an elegant
solution to power relay drive.
Simple DC-DC Converter
The simplest application for the MIC5060 is as a basic
one-chip DC-DC converter.
As the output (Gate) pin has relatively high impedance,
the output voltage shown will vary significantly with
applied load.
Figure 10. DC-DC Converter
Figure 8. Relay Driver
High Side Driver with Load Protection
Although the MIC5060 is reverse battery protected, the
load and power FET are not, in a typical high side
configuration. In the event of a reverse battery condition,
the internal body diode of the power FET will be forward
biased. This allows the reversed supply access to the
load.
The addition of a Schottky diode between the supply and
the FET eliminates this problem. The MBR2035CT was
chosen as it can withstand 20A continuous and 150A
peak, and should survive the rigors of an automotive
environment. The two diodes are paralleled to reduce
switch loss (forward voltage drop)
Motor Driver with Stall Shutdown
Tachometer feedback can be used to shut down a motor
driver circuit when a stall condition occurs. The control
switch is a 3-way type; the “START” position is
momentary and forces the driver ON. When released,
the switch returns to the “RUN” position, and the
tachometer’s output is used to hold the MIC5060 input
ON. If the motor slows down, the tach output is reduced,
and the MIC5060 switches OFF. Resistor “R” sets the
shutdown threshold.
Figure 11. High-Side Driver with Load Protection
Figure 9. Motor Stall Shutdown
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MIC5060
Package Information
8-Pin (3mm x 3mm) MLF® (ML)
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.
© 2009 Micrel, Incorporated.
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