MIC5016/5017

Micrel

October 1998

MIC5016/5017

Features

· 2.75V to 30V operation
· 100

A maximum supply current (5V supply)

· 15

A 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
· 1

A control input pull-off

· Inverting and noninverting versions

Applications

· Automotive electrical load control
· Battery-powered computer power management
· Lamp control
· Heater control
· Motor control
· Power bus switching

Ordering Information

Part Number

Temperature Range

Package

Noninverting

MIC5016BWM

C to +85

16-pin Wide SOIC

MIC5016BN

C to +85

14-pin Plastic DIP

Inverting

MIC5017BWM

C to +85

16-pin Wide SOIC

MIC5017BN

C to +85

14-pin Plastic DIP

MIC5016/5017

Low-Cost Dual High- or Low-Side MOSFET Driver

Final Information

Typical Application

Figure 1: 3-Volt "Sleep-Mode" Switches

with Logic-Level MOSFETs

OFF

MIC5016BN

IRLZ24

+3V to +4V

Gate A

Source B

Gnd

In A

V+ B

V+ A

Source A

Gate B

10µF

In B

Back
Light

IRLZ24

Logic

OFF

General Description

MIC5016 and MIC5017 dual MOSFET drivers are designed
for gate control of N-channel, enhancement-mode, power
MOSFETs used as high-side or low-side switches. The
MIC5016/7 can sustain an on-state output indefinitely.

The MIC5016/7 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 MIC5016/7 has two TTL compatible control inputs. The
MIC5016 is noninverting while the MIC5017 is inverting.

The MIC5016/7 features internal charge pumps that can
sustain gate voltages greater than the available supply
voltage. The driver is capable of turning on logic-level
MOSFETs from a 2.75V supply or standard MOSFETs from
a 5V supply. Gate-to-source output voltages are internally
limited to approximately 15V.

The MIC5016/7 is protected against automotive load dump,
reversed battery, and inductive load spikes of 20V. The
driver's overvoltage shutdown feature turns off the external
MOSFETs at approximately 35V to protect the load against
power supply excursions.

The MIC5016 is an improved pin-for-pin compatible replace-
ment in many MIC5012 applications.

The MIC5016/7 is available in plastic 14-pin DIP and 16-pin
SOIC pacakges.

Micrel, Inc. · 1849 Fortune Drive · San Jose, CA 95131 · USA · tel + 1 (408) 944-0800 · fax + 1 (408) 944-0970 · http://www.micrel.com

MIC5016/5017

Micrel

MIC5016/5017

October 1998

Block Diagram

1 of 2 Drivers per Package

Charge Pump

V+

Input

Ground

Source

Gate

15V

* Inverting version only

Connection Diagram

16-pin Wide SOIC

14-pin DIP

Source A

Gnd

Gate A

Source B

Gate B

V+ B

In B

V+ A

In A

N, J

Source A

Gnd

Gate A

Source B

Gate B

V+ B

In B

V+ A

In A

Pin Description

Pin Number

Pin Name

Pin Function

N, J Package

WM Package

Supply Pin A. Must be decoupled to isolate large transients caused by power
MOSFET drain. 10

F is recommended close to pins 12 and/or 10 and

ground. V

A and V

B may be connected to separate supplies.

Supply Pin B. See V

Input A

Turns on power MOSFET A when asserted. Requires approximately 1

A to

switch.

Input B

Turns on power MOSFET B. See Input A.

Gate A

Drives and clamps the gate of power MOSFET A

Gate B

Drives and clamps the gate of power MOSFET B

Source A

Connects the source lead of MOSFET A

Source B

Connects the source lead of MOSFET B

Gnd

Ground

MIC5016/5017

Micrel

October 1998

MIC5016/5017

Parameter

Conditions

Min

Typ

Max

Units

Supply Current

= 30V

De-Asserted (Note 5)

(Each Driver Channel)

Asserted (Note 5)

5.0

= 5V

De-Asserted

Asserted

100

= 3V

De-Asserted

Asserted

Logic Input Voltage Threshold

3.0V

30V

Digital Low Level

0.8

= 25

Digital High Level

2.0

Logic Input Current

3.0V

30V

Low

2.0

MIC5016 (non-inverting)

High

1.0

2.0

Logic Input Current

3.0V

30V

Low

2.0

1.0

MIC5017 (inverting)

High

1.0

2.0

Input Capacitance

5.0

Gate Enhancement

3.0V

30V

Asserted

4.0

GATE

- V

SUPPLY

Zener Clamp

8.0V

30V

Asserted

GATE

- V

SOURCE

Gate Turn-on Time, t

= 4.5V

switched on, measure

2.5

8.0

(Note 4)

= 1000pF

time for V

GATE

to reach V

+ 4V

= 12V

As above, measure time for

140

= 1000pF

GATE

to reach V

+ 4V

Gate Turn-off Time, t

OFF

= 4.5V

switched off, measure

6.0

(Note 4)

= 1000pF

time for V

GATE

to reach 1V

= 12V

As above, measure time for

6.0

= 1000pF

GATE

to reach 1V

Overvoltage Shutdown

Threshold

Electrical Characteristics

(Note 3) T

= 55

C to +125

C unless otherwise specified

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 MIC5016/5017 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 operating temperature 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. Maximum value of switching time seen at 125

C, unit operated at room temperature will reflect the typical value

shown.
Note 5: "Asserted" refers to a logic high on the MIC5016 and a logic low on the MIC5017.

Absolute Maximum Ratings

(Notes 1,2)

Operating Ratings

(Notes 1,2)

(Plastic DIP) ..................................................... 140

C/W

(SOIC) ............................................................. 110

C/W

Ambient Temperature: B version ................ 40

C to +85

Ambient Temperature: A version ............. +55

C to +125

Storage Temperature ................................ 65

C to +150

Lead Temperature ...................................................... 260

(max soldering time: 10 seconds)
Supply Voltage (V

) ......................................... 2.75V to 30V

Supply Voltage ............................................... 20V to 60V
Input Voltage ..................................................... 20V to V

Source Voltage .................................................. 20V to V

Source Current .......................................................... 50mA
Gate Voltage .................................................. 20V to 50V
Junction Temperature .............................................. 150

MIC5016/5017

Micrel

MIC5016/5017

October 1998

Typical Characteristics

All data measured using FET probe to minimize resistive loading

SUPPLY CURRENT (mA)

SUPPLY VOLTAGE (V)

Supply Current per Channel

(Output Asserted)

GATE ENHANCEMENT (V)

SUPPLY VOLTAGE (V)

Gate Enhancement

vs. Supply Voltage

Gate Enhancement =
V

GATE

SUPPLY

100

150

200

250

300

TURN-ON TIME (

GATE CAPACITANCE (nF)

High-Side Turn-On Time

vs. Gate Capacitance

Supply = 12V

0.01

0.1

100

TURN-ON TIME (ms)

SUPPLY VOLTAGE (V)

High-Side Turn-On Time
Until Gate = Supply + 4V

GATE

= 1300pF

0.01

0.1

100

TURN-ON TIME (ms)

SUPPLY VOLTAGE (V)

High-Side Turn-On Time
Until Gate = Supply + 4V

GATE

= 3000pF

100

120

140

160

180

-60 -30

90 120 150

HIGH-SIDE TURN-ON TIME (

AMBIENT TEMPERATURE (

High-Side Turn-On Time

vs. Temperature

Supply = 12V
C

GATE

= 1000pF

0.01

0.1

100

TURN-ON TIME (ms)

SUPPLY VOLTAGE (V)

High-Side Turn-On Time

Until Gate = Supply + 10V

GATE

= 1300pF

0.01

0.1

100

TURN-ON TIME (ms)

SUPPLY VOLTAGE (V)

High-Side Turn-On Time

Until Gate = Supply + 10V

GATE

= 3000pF

TURN-OFF TIME (

SUPPLY VOLTAGE (V)

High-Side Turn-Off Time

Until Gate = 1V

GATE

= 3000pF

GATE

1300pF

100

1000

OUTPUT CURRENT (

GATE-TO-SOURCE VOLTAGE (V)

Charge-Pump

Output Current

Source connected
to supply: supply
voltage as noted

12V

28V

100

1000

10000

OUTPUT CURRENT (

GATE-TO-SOURCE VOLTAGE (V)

Charge-Pump

Output Current

Source connected
to ground: supply
voltage as noted

12V

28V

100

1000

10000

TURN-ON TIME (

SUPPLY VOLTAGE (V)

Low-Side Turn-On Time

Until Gate = 4V

GATE

= 3000pF

GATE

= 1300pF

MIC5016/5017

Micrel

October 1998

MIC5016/5017

Applications Information

Functional Description

The MIC5016 is functionally compatible with the MIC5012,
and the MIC5017 is an inverting configuration of the MIC5016.

The internal functions of these devices are controlled via a
logic block (refer to block diagram) connected to the control
input (pin 14). When the input is off (low for the MIC5016, and
high for the MIC5017), 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;
15

A 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. This is a feature not found on the MIC5012.

The charge pump incorporates a 100kHz oscillator and on-
chip pump capacitors capable of charging a 1,000pF load in
90

s typical. In addition to providing active regulation, the

internal 15V zener is included to prevent exceeding the V

rating of the power MOSFET at high supply voltages.

The MIC5016/17 devices have been improved for greater
ruggedness and durability. All pins can withstand being
pulled 20 V 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 reaches 35V.

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 measure-
ments be affected, but it is possible to overstress various
components, especially electrolytic capacitors, with possibly
catastrophic results. A 10

F 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 50m

power MOSFET for

low voltage drop, but unless careful construction techniques
are used, one could easily add 50 to 100m

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 con-
tributing excess drop under load.

Low Voltage Testing As the MIC5016/5017 have 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 MIC5016 and MIC5017 are well suited for use with
standard power MOSFETs in both low and high side driver
configurations. In addition, the lowered supply voltage re-
quirements 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 V

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 V

CC.

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 consider-
ably by bootstrapping 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.

High Side Driver (Figure 1) The high side topology shown
here 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.

Low Side Driver (Figure 2) A key advantage of this topology,
as previously mentioned, is speed. The MOSFET gate is

Figure 2. Low Side Driver

Load

1/2 MIC5016

OFF

+3V to +30V

Gate

Gnd

Source

Input

V+

10µF

MIC5016/5017

Micrel

MIC5016/5017

October 1998

driven to near supply immediately when the MIC5016/17 is
turned on. Typical circuits reach full enhancement in 50

s or

less with a 15V supply.

Bootstrapped High Side Driver (Figure 3) The turn-on time
of a high side driver can be improved to faster than 40

s 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 current in the "OFF" state is only a
small leakage, the 100nF bypass capacitor tends to remain
charged for several seconds after the MIC5016/17 is turned
off. Faster switching 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 3. Bootstrapped High-Side Driver

High Side Driver With Current Sense (Figure 4) Although no
current sense function is included on the MIC5016/17 de-
vices, 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

TRIP

. The noninverting 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 above V

TRIP

, and

the output of the compara-

tor will be high which feeds the control input of the MIC5016
(polarities should be reversed if the MIC5017 is used). Once
the overcurrent trip point has been reached, the comparator

Load

1/2 MIC5016

Control Input

OFF

+2.75V to +30V

Gate

Gnd

Source

Input

V+

1µF

100nF

1N4001 (2)

1N5817

IRF540

will go low, which shuts off the MIC5016. When the short is
removed, feedback to the input pin insures that the MIC5016
will turn back on. This output can also be level shifted and sent
to an I/O port of a microcontroller for intelligent control.

Current Shunts (R

). Low valued resistors are necessary for

use at R

. Resistors are available with values ranging from 1

to 50m

, at 2 to10W. If a precise overcurrent trip point is not

necessary, then a nonprecision resistor or even a measured
PCB trace can serve as R

. 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.

Load

1/2 MIC5016

Gate

Gnd

Source

Input

V+

10µF

0.06

12V

R1
1k

R2
120k

LM301A

2.2k

TRIP

= V

TRIP

= 1.7A
V

TRIP

= R1/(R1+R2)

Figure 4. High Side Driver with Overcurrent Shutdown

Suppliers of Precision Power Resistors:
Dale Electronics, Inc., 2064 12th Ave., Columbus, NE 68601. (402) 565-3131
International Resistive Co., P.O. Box 1860, Boone,NC 28607-1860.
(704) 264-8861
Isotek Corp., 566 Wilbur Ave. Swansea, MA 02777. (508) 673-2900
Kelvin, 14724 Ventura Blvd., Ste. 1003, Sherman Oaks, CA 91403-3501.
(818) 990-1192
RCD Components, Inc., 520 E. Industrial Pk. Dr., Manchester, NH 03103.
(603) 669-0054
Ultronix, Inc., P.O. Box 1090, Grand Junction, CO 81502 (303) 242-0810

High Side Driver With Delayed Current Sense (Figure 5)
Delay of the overcurrent detection to accomodate high inrush
loads such as incandescent or halogen lamps can be accom-
plished by adding an LM3905 timer as a one shot to provide
an open collector pulldown for the comparator output such
that the control input of the MIC5017 stays low for a preset
amount of time without interference from the current sense
circuitry. Note that an MIC5017 must be used in this applica-
tion (figure 5), as an inverting control input is necessary. The
delay time is set by the RC time constant of the external
components on pins 3 and 4 of the timer; in this case, 6ms was
chosen.

An LM3905 timer was used instead of a 555 as it provides a
clean transition, and is almost impossible to make oscillate.
Good bypassing and noise immunity is essential in this circuit
to prevent spurious op amp oscillations.

MIC5016/5017

Micrel

October 1998

MIC5016/5017

1/2 MIC5016

OFF

IRFZ40

24V

Gate

Gnd

Source

Input

V+

1N4005

ASCO

8320A

Solenoid

Typical Applications

Variable Supply Low Side Driver for Motor Speed Control
(Figure 6) The internal regulation in the MIC5016/17 allows
a steady gate enhancement to be supplied while the MIC5016/
17 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: DC Motor Speed Control/Driver

Solenoid Valve Driver (Figure 7) 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 momen-
tarily 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 inadvertantly be dispensed at the wrong time with
possibly disasterous consequences. Also, too large of a
kickback voltage (as is found in larger solenoids) can damage
the MIC5016 or the power FET by forcing the Source node
below ground (the MIC5016 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 5k

resistor in series

with this diode has been included to set the recovery time of
the solenoid valve.

Figure 7: Solenoid Valve Driver

Figure 5. High Side Driver with Delayed Overcurrent Shutdown

Load

1/2 MIC5017

Gate

Gnd

Source

Input

V+

10µF

0.06

12V

120k

LM301A

2.2k

0.01µF

LM3905N

Logic

V+

Gnd

R/C

REF

Trigger

Emit

Coll

12V

1000pF

1/2 MIC5017

OFF

IRF540

= +5V to +30V

Gate

Gnd

Source

Input

V+

MIC5016/5017

Micrel

MIC5016/5017

October 1998

Motor Driver With Stall Shutdown (Figure 10) 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 MIC5016 input ON.
If the motor slows down, the tach output is reduced, and the
MIC5016 switches OFF. Resistor "R" sets the shutdown
threshold.

Figure 10. Motor Stall Shutdown

Simple DC-DC Converter (Figure 11) The simplest applica-
tion for the MIC5016 is as a basic one-chip DC-DC converter.
As the output (Gate) pin has a relatively high impedance, the
output voltage shown will vary significantly with applied load.

Incandescent/Halogen Lamp Driver (Figure 8) The combi-
nation of an MIC5016/5017 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.

If overcurrent sense is to be used, first measure the duration
of the inrush, then use the topology of Figure 5 with the RC of
the timer chosen to accomodate the duration with suitable
guardbanding.

Figure 8: Halogen Lamp Driver

Relay Driver (Figure 9) Some power relay applications re-
quire 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 MIC5016/
5017 and a power FET also provides an elegant solution to
power relay drive.

Figure 9: Relay Driver

Figure 11. DC - DC Converter

1/2 MIC5016

Control Input

OFF

IRF540

12V

Gate

Gnd

Source

Input

V+

10µF

OSRAM

HLX64623

1/2 MIC5016

Control Input

OFF

IRF540

12V

Gate

Gnd

Source

Input

V+

10µF

Guardian Electric

1725-1C-12D

1/2 MIC5016

Gate

Gnd

Source

Input

V+

10µF

OUT

= 12V

1/2 MIC5016

IRFZ44

12V

Gate

Gnd

Source

Input

V+

10µF

330k

1N4148

MIC5016/5017

Micrel

October 1998

MIC5016/5017

High Side Driver With Load Protection (Figure 12) Al-
though the MIC5016/17 devices are reverse battery pro-
tected, 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 to drive the load.

An MBR2035CT dual Schottky diode was used to eliminate
this problem. This particular diode can handle 20A continu-
ous current and 150A peak current; therefore it should survive
the rigors of an automotive environment. The diodes are
paralleled to reduce the switch loss (forward voltage drop).

Figure 12: High Side Driver WIth Load Protection

Push-Pull Driver With No Cross-Conduction (Figure 13)
As the turn-off time of the MIC5016/17 devices is much faster
than the turn-on time, a simple dual push-pull driver with no
cross conduction can be made using one MIC5016 and one
MIC5017. The same control signal is applied to both inputs;
the MIC5016 turns on with the positive signal, and the
MIC5017 turns on when it swings low.

Figure 13: Push-Pull Driver

This scheme works with no additional components as the
relative time difference between the rise and fall times of the
MIC5014 is large. However, this does mean that there is
considerable deadtime (time when neither driver is turned
on). If this circuit is used to drive an inductive load, catch
diodes must be used on each half to provide an alternate path
for the kickback current that will flow during this deadtime.

This circuit is also a simple H-bridge which can be driven with
a PWM signal on the input for SMPS or motor drive applica-
tions in which high switching frequencies are not desired.

Synchronous Rectifier (Figure 14) In applications where
efficiency in terms of low forward voltage drops and low diode
reverse-recovery losses is critical, power FETs are used to
achieve rectification instead of a conventional diode bridge.
Here, the power FETs are used in the third quadrant of the IV
characteristic curve (FETs are installed essentially "back-
wards"). The two FETs are connected such that the top FET
turns on with the positive going AC cycle, and turns off when
it swings negative. The bottom FET operates opposite to the
top FET.

In the first quadrant of operation, the limitation of the device
is determined by breakdown voltage. Here, we are limited by
the turn-on of a parasitic p-n body drain diode. If it is allowed
to conduct, its reverse recovery time will crowbar the other
power FET and possibly destroy it. The way to prevent this
is to keep the IR drop across the device below the cut-in
voltage of this diode; this is accomplished here by using a fast
comparator to sense this voltage and feed the appropriate
signal to the control inputs of the MIC5016 device. Obviously,
it is very important to use a comparator with a fast slew rate
such as the LM393, and fast recovery diodes. 3mV of positive
feedback is used on the comparator to prevent oscillations.

At 3A, with an R

(ON) of 0.077

, our forward voltage drop

per FET is ~ 0.2 V as opposed to the 0.7 to 0.8 V drop that a
normal diode would have. Even greater savings can be had
by using FETs with lower R

(ON)s, but care must be taken

that the peak currents and voltages do not exceed the SOA
of the chosen FET.

Figure 14: High Efficiency 60 Hz
Synchronous Rectifier

Load

1/2 MIC5016

Control Input

OFF

IRF540

12V

Gate

Gnd

Source

Input

V+

10µF

MBR2035CT

MIC5016

Control Input 1

IRFZ40

12V

Gate A

Source B

Gnd

In B

In A

V+ A

Source A

Gate B

10µF

MIC5017

Gate A

Gate B

In B

In A

V+ B

V+ A

Source A

Source B

12V

IRFZ40

OUT

Gnd

V+ B

Control Input 2

OUT

IRFZ40

IRFZ40
4

MIC5016

Gate A

Gate B

Gnd

In B

In A

V+ A

Source A

Source B

10µF

V+ B

56k

110V AC

Caltronics

T126C3

25.2V

30m

10k

1/2 LM393

1N914 (2)

1N914

1RF540

4700µF

OUT

18V, 3A

1RF540

1N914

* Parasitic body diode

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: MIC5017

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: MIC5017