MIC5022_05 [MICREL]
Half-Bridge MOSFET Driver; 半桥MOSFET驱动器
| 型号： | MIC5022_05 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | Half-Bridge MOSFET Driver |
| 文件： | 总10页 (文件大小：199K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC5022
Half-Bridge MOSFET Driver
Not Recommended for New Designs
General Description
Features
The MIC5022 half-bridge MOSFET driver is designed to
operate at frequencies up to 100kHz (5kHz PWM for 2%
to 100% duty cycle) and is an ideal choice for high speed
applications such as motor control and SMPS (switch mode
power supplies).
• 12V to 36V operation
• 600ns rise time into 1000pF (high side)
• TTL compatible input with internal pull-down resistor
• Outputs interlocked to prevent cross conduction
• TTL compatible enable
• Fault output indication
• Individual overcurrent limits
• Gate protection
• Internal charge pump (high-side)
• Current source drive scheme reduces EMI
Arising or falling edge on the input results in a current source
pulse or sink pulse on the gate outputs. This output current
pulse can turn on a 2000pF MOSFET in approximately 1µs.
The MIC5022 then supplies a limited current (< 2mA), if
necessary, to maintain the output states.
Two overcurrent comparators with nominal trip voltages of
50mV make the MIC5022 ideal for use with current sensing
MOSFETs. External low value resistors may be used instead
of sensing MOSFETs for more precise overcurrent control.
Optional external capacitors placed on the C and C pins
Applications
• Motor control
• Switch-mode power supplies
TH
TL
may be used to individually control the current shutdown duty
cycles from approximately 20% to <1%. Duty cycles from
20%toabout75%arepossiblewithindividualpull-upresistors
from C and C to V . An open collector output provides
Ordering Information
TL
TH
DD
Part Number
MIC5022BWM
MIC5022BN
Temperature Range
Package
a fault indication when either sense input is tripped.
–40°C to +85°C
16-pin Wide SOIC
14-pin Plastic DIP
The MIC5022 is available in 16-pin wide SOIC and 14-pin
plastic DIP packages.
–40°C to +85°C
Other members of the MIC502x family include the MIC5020
low-side driver and the MIC5021 high-side driver.
Typical Application
+12V to +36V
MIC5022
1
VDD
14
13
12
11
10
9
VBOOST
10µF
2
TTL Input
Input
Gate H
2.7nF
M
(PWM signal)
3
4
5
6
7
Fault Sense H–
RS1
CTH
Sense H+
Gate L
CTH
CTL
Enable
CTL
Sense L–
Sense L+
RS2
8
Gnd
DC Motor Control Application
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
July 2005
1
MIC5022
MIC5022
Micrel, Inc.
Pin Configuration
VDD
VBOOST 14
Gate H 13
1
2
3
4
5
6
7
8
VDD
NC
NC 16
VBOOST 15
Gate H 14
1
2
3
4
5
6
7
Input
Fault Sense H– 12
Input
CTH
Sense H+ 11
Gate L 10
Fault Sense H– 13
CTH Sense H+ 12
Enable Gate L 11
Enable
CTL
Sense L–
Sense L+
9
8
Gnd
CTL
Sense L– 10
Gnd Sense L+
9
DIP Package
(N)
SOIC Package
(WM)
Pin Description
DIP Pin No.
SOIC Pin No.
Pin Name
Pin Function
1
2
1
3
VDD
Supply: +12V to +36V. Decouple with ≥ 10µF capacitor.
Input
TTL Compatible Input: Logic high turns the high-side external MOSFET
on and the low-side external MOSFET off. Logic low turns the high-side
external MOSFET off and the low-side external MOSFET on. An internal
pull-down returns an open pin to logic low.
3
4
4
5
Fault
CTH
When either sense voltage exceeds threshold, open collector output is open
circuit for 5µs (tG(ON)), then pulled low for tG(OFF). tG(OFF) is adjustable from
CT.
Retry Trimming Capacitor, High Side: Controls the off time (tG(OFF)) of the
overcurrent retry cycle. (Duty cycle adjustment.)
• Open = approx. 20% duty cycle.
• Capacitor to Ground = approx. 20% to < 1% duty cycle.
• Pullup resistor = approx. 20% to approx. 75% duty cycle.
• Ground = maintained shutdown upon overcurrent condition.
5
6
Enable
Output Enable: Disables operation of the output drivers; active high. An
internal pull-down returns an open pin to logic low.
6
7
8
7
8
8
CTL
Retry Trimming Capacitor, Low Side: Same function as CTH
.
Gnd
Circuit Ground
Sense L +
Current Sense Comparator (+) Input, Low Side: Connect to source of low-
side MOSFET. A built-in offset (nominal 50mV) in conjunction with RSENSE
sets the load overcurrent trip point.
9
10
11
Sense L –
Gate L
Current Sense Comparator (–) Input, Low Side: Connect to the negative
side of the low-side sense resistor.
10
Gate Drive, Low Side: Drives the gate of an external power MOSFET. Also
limits VGS to 15V max. to prevent Gate to Source damage. Will sink and
source current.
11
12
Sense H +
Current Sense Comparator (+) Input, High Side: Connect to source of high-
side MOSFET. A built-in offset (nominal 50mV) in conjunction with RSENSE
sets the load overcurrent trip point.
12
13
13
14
Source H –
Gate H
Current Sense Comparator (–) Input, High Side: Connect to the negative
side of the high-side sense resistor.
Gate Drive, High Side: Drives the gate of an external power MOSFET. Also
limits VGS to 15V max. to prevent Gate to Source damage. Will sink and
source current.
14
15
VBOOST
Charge Pump Boost Capacitor: A bootstrap capacitor from VBOOST to
the MOSFET source pin supplies charge to quickly enhance the external
MOSFET’s gate .
MIC5022
2
July 2005
MIC5022
Micrel, Inc.
Block Diagram
6V Internal Regulator
I1
Fault
CTH
VDD
CINT
2I1
Normal
CHARGE
PUMP
VBOOST
Sense H+
Sense H–
Q1
1.4V
50mV
15V
ON
OFF
Input
6V
↑
↓
ONE-
SHOT
10I2
I2
Gate H
6V
I1
Fault
CTL
CINT
2I1
Normal
Fault
Sense L+
Sense L–
Q1
50mV
VDD
15V
ON
OFF
1.4V
6V
↑
↓
ONE-
SHOT
10I2
I2
Gate L
Enable
Transistor Count: 188
Absolute Maximum Ratings
Operating Ratings
Supply Voltage (V )...................................................+40V
Supply Voltage (V )..................................... +12V to +36V
DD
DD
Input Voltage ...................................................–0.5V to 15V
Sense Differential Voltage ..........................................±6.5V
Sense + or Sense – to Gnd...........................–0.5V to +36V
Fault Voltage ...............................................................+36V
Current into Fault........................................................ 50mA
Temperature Range
SOIC ...................................................... –40°C to +85°C
....................................................................
PDIP
–40°C to +85°C
Timer Voltage (C )......................................................+5.5V
T
V
Capacitor..................................................... 0.01µF
BOOST
July 2005
3
MIC5022
MIC5022
Micrel, Inc.
Electrical Characteristics
TA = 25°C, Gnd = 0V, VDD = 12V, Gate CL = 1500pF (IRF540 MOSFET) unless otherwise specificed
Symbol
Parameter
Condition
Min
Typ
2.5
6.0
2.4
3.0
1.4
0.1
20
Max
Units
mA
mA
mA
mA
V
D.C. Supply Current
VDD = 12V, Input = 0V
VDD = 36V, Input = 0V
VDD = 12V, Input = 5V
VDD = 36V, Input = 5V
5
10
5
25
2.0
Input Threshold
0.8
Input Hysteresis
V
Input Pull-Down Current
Enable Threshold
Enable Hysteresis
Input = 5V
10
40
µA
V
0.8
1.4
0.1
0.15
2.0
V
Fault Output
Fault Current = 1.6mA
0.4
V
Saturation Voltage
Note 1
Fault Output Leakage
Fault = 36V
–1
30
30
16
46
10
14
2
0.01
50
+1
70
70
21
52
µA
mV
mV
V
Current Limit Thresh., Low-Side
Current Limit Thresh., High-Side
Gate On Voltage, High-Side
Note 2
Note 2
50
VDD = 12V, Note 3
VDD = 36V, Note 3
VDD = 12V, Note 3
VDD = 36V, Note 3
Sense Differential > 70mV
Sense Differential > 70mV, CT = 0pF
Note 4
18
49
V
Gate On Voltage, Low-Side
11
V
15
18
10
V
tG(ON)
tG(OFF)
tDLH
tR
Gate On Time, Fixed
5
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
Gate Off Time, Adjustable
Gate Turn-On Delay, High-Side
Gate Rise Time, High-Side
Gate Turn-Off Delay, High-Side
Gate Fall Time, High-Side
Gate Turn-On Delay, Low-Side
Gate Rise Time, Low-Side
Gate Turn-Off Delay, Low-Side
Gate Fall Time, Low-Side
10
20
50
1.4
0.8
1.2
0.6
1.7
0.7
0.5
1.0
2.0
1.5
2.0
1.5
2.5
1.5
1.0
1.5
Note 5
tDHL
tF
tDLH
tR
tDHL
tF
Note 6
Note 7
Note 4
Note 8
Note 9
Note 10
Note 1 Voltage remains low for time affected by CT.
Note 2 When using sense MOSFETs, it is recommended that RSENSE < 50Ω. Higher values may affect the sense MOSFET’s current transfer ratio.
Note 3 DC measurement.
Note 4 Input switched from 0.8V (TTL low) to 2.0V (TTL high), time for Gate transition from 0V to 2V.
Note 5 Input switched from 0.8V (TTL low) to 2.0V (TTL high), time for Gate transition from 2V to 17V.
Note 6 Input switched from 2.0V (TTL high) to 0.8V (TTL low), time for Gate transition from 20V (Gate on voltage) to 17V.
Note 7 Input switched from 2.0V (TTL high) to 0.8V (TTL low), time for Gate transition from 17V to 2V.
Note 8 Input switched from 0.8V (TTL low) to 2.0V (TTL high), time for Gate transition from 2V to 10V.
Note 9 Input switched from 2.0V (TTL high) to 0.8V (TTL low), time for Gate transition from 15V (Gate on voltage) to 10V.
Note 10 Input switched from 2.0V (TTL high) to 0.8V (TTL low), time for Gate transition from 10V to 2V.
MIC5022
4
July 2005
MIC5022
Micrel, Inc.
Typical Characteristics
Gate to Source Voltage
vs. Supply Voltage
Gate Turn-On Delay vs.
Supply Current vs.
Supply Voltage
Supply Voltage
6.0
25
20
15
10
5
2.5
2.0
1.5
1.0
0.5
0.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
VIN = 0V
VGATE = VSUPPLY + 4V
CL = CH = 1500pF
CBOOST = 0.01µF
VIN = 5V
NOTE: INCLUDES PROPAGATION
DELAY & CROSS CONDUCTION
LOCKOUT
0
5
10 15 20 25 30 35 40
VSUPPLY (V)
5
10 15 20 25 30 35 40
VSUPPLY (V)
5
10 15 20 25 30 35 40
VSUPPLY (V)
Gate Turn-On Delay vs.
Supply Voltage
Gate Turn-On/Off Delay vs.
Gate Capacitance
Gate Turn-On/Off Delay vs.
Gate Capacitance
2.5
2
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
3.5
3.0
2.5
VGATE H = VSUPPLY + 4V
CL = CH
VSUPPLY = 12V
VGATE L = 4V
CL = CH
VSUPPLY = 12V
1.5
1
LOW-SIDE
VGATE H = VSUPPLY + 10V
CL = CH = 1500pF
CBOOST = 0.01µF
HIGH-SIDE
2.0 NOTE: INCLUDES
PROPAGATION
PROP.
DELAY
DELAY & CROSS
CONDUCTION
1.5 LOCKOUT
PROP.
DELAY
NOTE: INCLUDES PROPAGATION
DELAY & CROSS CONDUCTION
LOCKOUT
0.5
0
NOTE: INCLUDES PROPAGATION
DELAY & CROSS CONDUCTION
LOCKOUT
1.0
5
10 15 20 25 30 35 40
VSUPPLY (V)
0
1
2
5
0
1
2
5
1x10 1x10 1x10 1x103 1x104 1x10
1x10 1x10 1x10 1x103 1x104 1x10
CGATE (pF)
CGATE (pF)
Overcurrent Retry Duty
Overcurrent Retry Duty
Cycle vs. Timing Capacitance
Input Current vs.
Input Voltage
Cycle vs. Timing Capacitance
25
25.0
100
tON = 5µS
VSUPPLY = 12V
tON = 5µS
VSUPPLY = 12V
20.0
VSUPPLY = 12V
20
15
10
5
80
60
40
20
0
HIGH SIDE
15.0
10.0
5.0
LOW SIDE
NOTE:
tON, tOFF TIME
INDEPENDENT
OF V
SUPPLY
0
0.0
0
5
10
VIN (V)
15
20
25
0.1
1
10 100 1000 10000
CTH (pF)
0.1
1
10 100 1000 10000
CTL (pF)
Sense Threshold vs.
Temperature
80
70
60
50
40
30
20
-60 -30
0
30 60 90 120 150
TEMPERATURE°(C)
July 2005
5
MIC5022
MIC5022
Micrel, Inc.
TTL (H)
0V
Input
TTL (H)
0V
Enable
Gate H 15V (max.)
Source
Gate L 15V (max.)
0V
50mV
Sense H+, H–
Differential
0V
50mV
0V
Sense L+, L–
Differential
Off
Fault
On
Timing Diagram 1. Normal Operation
5µs
20µs
TTL (H)
0V
Input
TTL (H)
0V
Enable
Gate H 15V (max.)
0V
Gate L 15V (max.)
0V
Sense H+, H–
50mV
0V
Differential
Sense L+, L–
Differential
50mV
0V
Off
Fault
On
Timing Diagram 2. Overcurrent Fault with Retry
5µs
TTL (H)
Input
0V
TTL (H)
Enable
0V
Gate H 15V (max.)
Source
Gate L 15V (max.)
0V
Sense H+, H–
50mV
0V
Differential
Sense L+, L–
Differential
50mV
0V
Off
Fault
On
Timing Diagram 3. Overcurrent Fault with Maintained Off
MIC5022
6
July 2005
MIC5022
Micrel, Inc.
Functional Description
Refer to the MIC5022 block diagram.
Input
the voltage on the source side of the capacitor increases
(because it is on the high side of the load) raising the V
BOOST
pin voltage. The boost capacitor charge is directed through
thegatepintoquicklychargetheFET’sgateto15Vmaximum
A signal greater than 1.4V (nominal) applied to the MIC5022
INPUT causes gate enhancement on an external MOSFET
connected to GATE H turning the high-side MOSFET on.
above V . The internal charge pump maintains the gate
DD
voltage by supplying a small current as needed.
At the same time internal logic removes gate enhancement
from an external MOSFET connected to GATE L, turning the
low-side MOSFET off.
Overcurrent Limiting (High or Low-Side)
Current source I charges C
upon power up. An optional
INT
1
externalcapacitorconnectedtoC iskeptdischargedthrough
T
An internal pull-down resistor insures that an open INPUT
remains low, keeping the external high-side MOSFET turned
off and the low-side MOSFET turned on.
a FET Q1.
A fault condition (> 50mV from SENSE + to SENSE –) causes
the overcurrent comparator to enable current sink 2I which
1
Enable (Active Low)
overcomes current source I to discharge C
in about 5µs
1
INT
A signal greater than 1.4V (nominal) applied to the MIC5022
ENABLE keeps both GATE outputs off. An internal pull-down
resistor insures that the MIC5022 is enabled if the pin is
open.
time. When C
is discharged, the INPUT is disabled, the
INT
FAULT output is enabled, and C
and C are ready to be
INT
T
charged. Since the INPUT is disabled the GATE output turns
off.
Gate Outputs
When the GATE output turns off the FET, the overcurrent
signal is removed from the sense inputs which deactivates
Rapid rise and fall times on the GATE output are possible
because each input state change triggers a one-shot which
activates a high-value current sink (10I ) for a short time.
current sink 2I . This allows C
and the optional capacitor
1
INT
connected to C to recharge. A Schmitt trigger delays the
2
T
This draws a high current though a current mirror circuit
causing the output transistors to quickly charge or discharge
the external FET’s gate.
retrywhilethecapacitor(s)recharge. Retrydelayisincreased
by connecting a capacitor connected to C (optional).
T
The MIC5022’s low-side driver may be used without current
sensing by grounding both SENSE + and SENSE – pins. The
high-side driver may be used without current sensing by con-
necting SENSE + and SENSE – to the source of the external
high-side MOSFET.
A second current sink continuously draws the lower value
of current used to maintain the gate voltage for the selected
state.
Internal 15V Zener diodes protect the external high-side and
low-side MOSFETs by limiting the gate to source voltage.
Fault Output
Charge Pump (High-Side)
The FAULT output is an open collector transistor. FAULT is
active at approximately the same time the output is disabled
by a fault condition (5µs after an overcurrent condition is
sensed). The FAULT output is open circuit (off) during each
successive retry (5µs).
Aninternalchargepumputilizesanexternal“boost”capacitor
connected between V
and the source of the external
BOOST
FET(refer toTypicalApplication). The boost capacitor stores
charge when the FET is off. As the FET begins to turn on
Typical Full-Bridge Application
+12V to +20V
MIC5022
MIC5022
VBOOST
Gate H
10µF
10µF
1
2
3
4
5
6
7
14
13
12
11
10
9
14
13
12
11
10
9
1
2
3
4
5
6
7
VDD
VBOOST
Gate H
VDD
0.01µF
0.01µF
TTL Input
(PWM signal)
TTL Input
(PWM signal)
Input
Input
Fault Sense H–
CTH Sense H+
Enable Gate L
Sense H– Fault
Sense H+ CTH
Gate L Enable
Load
CTL
Sense L–
Sense L–
CTL
8
8
Gnd Sense L+
Sense L+ Gnd
Figure 1. Basic Full-Bridge Circuit
July 2005
7
MIC5022
MIC5022
Micrel, Inc.
Applications Information
The MIC5022 MOSFET driver is designed for half-bridge
switching applications where overcurrent limiting and high
speed are required. The MIC5022 can control MOSFETs
that switch voltages up to 36V.
Circuits Without Current Sensing
Current sensing may be omitted by connecting the high-side
SENSE+andSENSE–pinstothesourceoftheMOSFETorthe
supplyandthelow-sideSENSE+andSENSE–pinstoground.
Do not connect the high-side sense pins to ground.
TheMIC5022functionallyincludestheMIC5020andMIC5021
withadditionalcircuitrytocoordinatetheoperationofthehigh
and low-side drivers. Since most output considerations are
similar, refer to the MIC5020 and MIC5021 data sheets for
additional applications information.
Inductive Load Precautions
Circuits controlling inductive loads require precautions when
controlled by the MIC5022. Wire wound resistors, which
are sometimes used to simulate other loads, can also show
significant inductive properties.
Supply Voltage
The MIC5022’s supply input (V ) is rated up to 36V. The
supply voltage must be equal to or greater than the voltage
applied to the drain of the external N-channel MOSFET.
DD
Sense Pin Considerations
The sense pins of the MIC5022 are sensitive to negative volt-
ages. If a voltage spike is too negative (below approximately
–0.5V), current will be drawn from functional sections of the
IC resulting in unpredictable circuit behavior or damage.
Resistors and Schottky diodes may be used to protect the
sense pins from the negative spikes. Refer to the MIC5021
data sheet for details.
A16V minimum supply is recommended to produce continu-
ous on-state, gate drive voltage for standard MOSFETs (10V
nominal gate enhancement).
When the driver is powered from a 12V to 16V supply, a
logic-level MOSFET is recommended (5V nominal gate
enhancement).
High-Side Sensing
PWMoperationmayproducesatisfactorygateenhancement
at lower supply voltages. This occurs when fast switching
repetition makes the boost capacitor a more significant volt-
age supply than the internal charge pump.
For the high-side driver, sensing the current on the supply
side of the high-side MOSFET locates the SENSE pins away
from the inductive spike. Refer to the MIC5021 data sheet
for details.
Overcurrent Limiting
Low-Temperature Operation
Separate high and low-side 50mV comparators are provided
for current sensing. The low level trip point minimizes I R
losses when a power resistor is used for current sensing.
As the temperature of the MIC5022AJB (extended tempera-
ture range version—no longer available) approaches –55°C,
thedriver’soff-state,gate-outputoffsetfromgroundincreases.
If the operating environment of the MIC5022AJB includes
low temperatures (–40°C to –55°C), add an external 2.2MΩ
resistor from gate-to-source or from gate-to-ground. This
assures that the driver’s gate-to-source voltage is far below
the external MOSFET’s gate threshold voltage, forcing the
MOSFET fully off. Refer to the MIC5020 and MIC5021 data
sheets for examples.
2
The adjustable retry feature can be used to handle loads with
high initial currents, such as lamps or heating elements, and
can be adjusted from the C connection.
T
C to ground causes maintained gate drive shutdown follow-
T
ing an overcurrent condition.
C open, or a capacitor to ground, causes automatic retry.
T
The default duty cycle (C open) is approximately 20% (the
T
The gate-to-source configuration is appropriate for resistive
and inductive loads. This also causes the smallest decrease
in gate output voltage.
high side is slightly greater than the low side). Refer to the
typical characteristics when selecting a capacitor for a re-
duced duty cycle.
The gate-to-ground configuration is appropriate for resistive,
inductive,orcapacitiveloads.Thisconfigurationwillde-crease
the gate output voltage slightly more than the gate-to-source
configuration.
C through a pull-up resistor to V increases the duty cycle.
T
DD
Increasing the duty cycle increases the power dissipation
in the load and MOSFET under a “fault” condition. Circuits
may become unstable at a duty cycle of about 75% or higher,
depending on conditions. Caution: The MIC5022 may be
Full-Bridge Motor Control
damaged if the voltage applied to C exceeds the absolute
maximum voltage rating.
T
An application for two MIC5022s is the full-bridge motor
control circuit.
Boost Capacitor Selection
Two high or two low-side sense inputs may be used for over-
current detection. (Low-side sensing is shown in Figure 2).
Sensing at four locations is usually unnecessary.
For 12V to 20V operation, the boost capacitor should be
0.01µF; and for 12V to 36V operation, the boost capacitor
should be 2.7nF; both connected between V
MOSFET source. The preferred configuration for 20V to 36V
operation is a 0.01µF capacitor connected between V
and the
BOOST
Whenswitchinginductiveloads,suchasmotors,itisdesirable
to place the high-side sense inputs on the supply side of the
MOSFETs. The helps prevent the inductive spikes that occur
upon load shutoff from affecting the sense inputs.
BOOST
and V . Refer to the MIC5021 data sheet for examples.
DD
DonotconnectcapacitorsbetweenV
andtheMOSFET
BOOST
sourceandbetweenV
andV atthesametime. Larger
BOOST
DD
capacitors than specified may damage the MIC5022.
MIC5022
8
July 2005
MIC5022
Micrel, Inc.
+12V to +20V
MIC5022
MIC5022
VBOOST
Gate H
10µF
10µF
1
2
3
4
5
6
7
14
13
12
11
10
9
14
13
12
11
10
9
1
2
3
4
5
6
7
VDD
Input
VBOOST
Gate H
VDD
TTL Input
(PWM signal)
TTL Input
(PWM signal)
Input
Fault Sense H–
CTH Sense H+
Enable Gate L
Sense H– Fault
Sense H+ CTH
Gate L Enable
0.01µF
0.01µF
M
CTL
Sense L–
Sense L–
CTL
RS2
RS1
8
8
Gnd Sense L+
Sense L+ Gnd
Figure 2. Full-Bridge Motor Control Application
Synchronous Rectifier Converter
The MIC5022 can be part of a synchronous rectifier in SMPS
(switch mode power supply) applications.
forced through the inductor to the output capacitor and load.
When the pass transistor is switched off, the synchronous
rectifier is switched on allowing current to continue to flow
as the inductor returns stored energy.
This circuit uses the MIC38C43 SMPS controller IC to switch
a pass transistor (Q1) and a “synchronous rectifier” transistor
(Q2) using the MIC5022.
The synchronous rectifier MOSFET has a lower voltage drop
than the forward voltage drop across a Schottky diode. This
increases converter efficiency which extends battery life in
portable equipment.
The MIC38C43 controller switches the transistors at 50kHz.
Output regulation is maintained using PWM. When the pass
transistor is on, the synchronous rectifier is off and current is
+12V
10k
0.1µF
470µF
25V
SMP06N06-14
Q1
MIC5022
13k
13
14
10
11
12
3
1
5
2
8
9
7
VOUT
0.1µF
V+
Gate H
VPP
70µH
5V, 8A
300k
5mΩ
0.15µF
47k
Enable
Input
S L+
S L–
MIC38C43
Gate L
S H+
S H–
Fault
4.7nF
4.3k
1
2
3
4
8
7
6
5
Q2
Comp
VREF
VDD
1000µF
Low ESR
FB
IS
VOUT
Gnd
Gnd
3.3k
RT/CT
2200pF
10k
Figure 3. 50kHz Synchronous Rectifier Converter
July 2005
9
MIC5022
MIC5022
Micrel, Inc.
Package Information
.770 (19.558) MAX
PIN 1
.235 (5.969)
.215 (5.461)
.060 (1.524)
.045 (1.143)
.310 (7.874)
.280 (7.112)
.160 MAX
(4.064)
.080 (1.524)
.015 (0.381)
.015 (0.381)
.008 (0.2032)
.160 (4.064)
.100 (2.540)
.110 (2.794)
.090 (2.296)
.023 (.5842)
.015 (.3810)
.400 (10.180)
.330 (8.362)
.060 (1.524)
.045 (1.143)
14-Pin Plastic DIP (N)
PIN 1
DIMENSIONS:
INCHES (MM)
0.301 (7.645)
0.297 (7.544)
0.027 (0.686)
0.031 (0.787)
0.297 (7.544)
0.293 (7.442)
0.103 (2.616)
0.099 (2.515)
0.050 (1.270) 0.016 (0.046)
TYP TYP
0.022 (0.559)
0.018 (0.457)
7°
TYP
R
0.015
(0.381)
5°
TYP
0.330 (8.382)
0.326 (8.280)
0.015
(0.381)
MIN
0.409 (10.389)
0.405 (10.287)
10° TYP
0.094 (2.388)
0.090 (2.286)
SEATING
PLANE
0.032 (0.813) TYP
0.408 (10.363)
0.404 (10.262)
16-Pin Wide SOIC (M)
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.
© 2003 Micrel, Inc.
MIC5022
10
July 2005
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