MIC4608 - Micrel

MIC4608
600V Half Bridge MOSFET or IGBT Driver
General Description
Features
The MIC4608 is a 600V Half Bridge IGBT or MOSFET
driver. The MIC4608 features a 450ns propagation delay
including a 200ns input filtering time to prevent unwanted
pulses. The low-side and high-side gate drivers are
independently controlled (with shoot thru protection) or
controlled with a single PWM signal. The MIC4608 has
TTL input thresholds.
• Gate drive supply voltage up to 20V
• Drives high-side and low-side N-Channel MOSFETs or
IGBTs with independent inputs or with a single PWM
signal
• ±50V/ns dV/dt immunity
• TTL input thresholds
• 200ns input filtering time
• Shoot thru protection
• Low power consumption
• Supply undervoltage protection
• –40°C to +125°C junction temperature range
The robust operation of the MIC4608 ensures that the
outputs are not affected by supply glitches, HS ringing
below ground, or HS slewing with high-speed voltage
transitions. Undervoltage protection is provided on both
the low-side and high-side drivers.
The MIC4608 is available in a 14-pin SOIC package. The
MIC4608 has an operating junction temperature range of
–40°C to +125°C.
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Applications
• Full- and half-bridge motor drive
• Industrial controls
• White goods
Typical Application
Half–Bridge Motor Driver
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
May 12, 2015
Revision 1.0
Micrel, Inc.
MIC4608
Ordering Information
Part Number
Input
Junction Temperature Range
Package
MIC4608YM
TTL
–40°C to +125°C
14-Pin SOIC
Pin Configuration
14-Pin SOIC (M)
(Top View)
Pin Description
Pin Number
Pin Name
1
EN
2
VDD
Input supply for gate drivers. Decouple this pin to VSS with a >2.2µF capacitor. Bootstrap diode
connected to HB.
3
VDD
Input supply for gate drivers. Connect directly to pin 2.
4
NC
No connection.
5
HB
High-side bootstrap supply. External bootstrap capacitor is required. Connect bootstrap capacitor
across this pin and HS. An external bootstrap diode is connected to this pin as well.
6
HO
High-side drive output. Connect to gate of the external low-side power MOSFET or IGBT.
7
HS
High-side drive reference connection. Connect to source/emitter of the external high-side power
MOSFET or IGBT. Decouple this pin with the bootstrap capacitor to HB.
8
NC
No connection
9
HI
High-side drive input and PWM input for single signal drive. This pin has an internal 300kΩ pulldown resistor to VSS.
10
LI
Low-side drive input. This pin has an internal 300kΩ pull-down resistor to VSS.
11
VSS
Driver Reference supply input. Generally connected to power ground of external circuitry.
12
LO
Low-side drive output. Connect to gate of the external low-side power MOSFET or IGBT.
13
ST
State pin. PWM or Independent drive. Logic low allows for independent operation and logic high
allows for single input PWM drive operation. This pin has an internal 300kΩ pull-down resistor to
VSS.
14
NC
No connection.
May 12, 2015
Pin Function
A high level on this pin enables the driver. A low level disables the drivers and places the part in a
low quiescent current state. This pin has an internal 300kΩ pull-down resistor to VSS.
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Revision 1.0
Micrel, Inc.
MIC4608
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VDD, VHB – VHS) ..................... –0.3V to 25V
Input Voltages (VLI, VHI, VST, VEN).......... –0.3V to VDD +0.3V
Voltage on LO (VLO) ............................. –0.3V to VDD + 0.3V
Voltage on HO (VHO) ...................... VHS –0.3V to VHB + 0.3V
Voltage on HS (continuous) ......................... –25V to +630V
Voltage on HB ............................................................ +655V
HS Slew Rate ............................................................ 50V/ns
Storage Temperature (TS) ......................... –60°C to +150°C
ESD Rating(3)
HBM ...................................................................... 1.5kV
MM ......................................................................... 150V
Supply Voltage (VDD) .......................................... 10V to 20V
Input Voltages (VLI, VHI, VST, VEN) ......................... 0V to VDD
Voltage on HS (repetitive transient) ............5V–VDD to 600V
Voltage on HB ................................... VHS +10V to VHS +20V
and/or.......................................... VDD –1V to VDD +600V
Junction Temperature (TJ) ........................ –40°C to +125°C
Junction Thermal Resistance
14-Pin SOIC (θJA) ............................................ 105°C/W
Electrical Characteristics(3)(4)
VDD = VHB = 20V; VSS = VHS = 0V; VST = 0V; No load on LO or HO; TA = 25°C, unless noted. Bold values indicate –40°C≤ TJ ≤ +125°C.
Symbol
Parameter
Condition
Min.
Typ.
Max.
Units
VHI = VLI = 0V
42
100
µA
VEN = 0V, HS = floating
0.1
1
VEN = 0V, VHS = 0V
0.1
1
Supply Current
IDD
VDD Quiescent Current
IDDSH
VDD Shutdown Current
IDDO
VDD Operating Current
f = 20kHz
150
350
µA
IHB
Total HB Quiescent Current
VLI = VHI = 0V or VLI = 0V and VHI = 10V
35
100
µA
IHBO
Total HB Operating Current
f = 20kHz
210
400
µA
0.8
V
µA
Input (TTL: LI and HI)
VIL
Low-Level Input Voltage
VIH
High-Level Input Voltage
VHYS
Input Voltage Hysteresis
IHI_LI
Input Current
RI
Input Pull-Down Resistance
2.2
VLI = VHI = 20V
V
0.2
V
57
µA
300
kΩ
Input (TTL: EN and ST)
VIL
Low-Level Input Voltage
VIH
High-Level Input Voltage
VHYS
Input Voltage Hysteresis
IHI_LI
Pin Current
RI
Input Pull-Down Resistance
0.8
2.2
VLI = VHI = 20V
V
V
0.2
V
57
µA
300
kΩ
Notes:
1. Exceeding the absolute maximum ratings may damage the device.
2. The device is not guaranteed to function outside its operating ratings.
3. Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5kΩ in series with 100pF.
4. Specification for packaged product only.
May 12, 2015
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Revision 1.0
Micrel, Inc.
MIC4608
Electrical Characteristics(3)(4) (Continued)
VDD = VHB = 20V; VSS = VHS = 0V; VST = 0V; No load on LO or HO; TA = 25°C, unless noted. Bold values indicate –40°C≤ TJ ≤ +125°C.
Symbol
Parameter
Condition
Min.
Typ.
Max.
Units
7.0
8.5
9.6
V
Undervoltage Protection
VDDR
VDDH
VHBR
VHBH
VDD Falling Threshold
VDD Rising Threshold
9.0
V
VDD Threshold Hysteresis
0.5
V
7.0
HB Falling Threshold
8.0
9.0
V
HB Rising Threshold
8.5
V
HB Threshold Hysteresis
0.5
V
LO Gate Driver
VOLL
Low-Level Output Voltage
ILO = 50mA
0.46
0.9
V
VOHL
High-Level Output Voltage
ILO = −50mA, VOHL = VDD - VLO
0.46
0.9
V
IOHL
Peak Sink Current
VLO = 0V
IOLL
Peak Source Current
1
A
1
A
HO Gate Driver
VOLH
Low-Level Output Voltage
IHO = 50mA
0.4
0.9
V
VOHH
High-Level Output Voltage
IHO = −50mA, VOHH = VHB – VHO
0.4
0.9
V
IOHH
Peak Sink Current
VHO = 0V
IOLH
Peak Source Current
1
A
1
A
Switching Specifications (VLI/HI high level=10V; CLOAD on HO/LO = 1.15nF)
fs
Switching Frequency Range
25
kHz
tHI_LI_OL
Overlap Timing Between LI/HI
20
ns
tON
Turn-On Propagation Delay
VST = 0V; LI to LO or HI to HO
300
450
600
ns
tOFF
Turn-Off Propagation Delay
VST = 0V; LI to LO or HI to HO
300
450
600
ns
tON
HO Turn-On Propagation Delay
VST = 20V; HI Rising to HO Rising
520
850
1020
ns
tON
LO Turn-On Propagation Delay
VST = 20V; HI Falling to LO Rising
520
750
1020
ns
tOFF
HO Turn-Off Propagation Delay
VST = 20V; HI Falling to HO Falling
300
450
600
ns
tOFF
LO Turn-Off Propagation Delay
VST = 20V; HI Rising to LO Falling
400
615
1020
ns
tEN_RISE
Enable Turn-On Prop Delay
EN to HO or LO
2800
ns
tEN_FALL
Enable Turn-Off Prop Delay
EN to HO or LO
600
ns
tR
Turn-On Rise Time
31
60
ns
tF
Turn-Off Fall Time
31
60
ns
tFLTR
Input Filtering Time
160
200
320
ns
tD
Dead Time
220
300
420
ns
tPW
Minimum Input Pulse Width that
Changes the Output
LI, HI, EN, ST pins
Note 5
350
ns
Note:
5. Guaranteed by design. Not production tested.
May 12, 2015
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Micrel, Inc.
MIC4608
Timing Diagram
Figure 1. Minimum Pulse Width diagram
Figure 2. Dead Time, Propagation Delay and Rise/Fall Time Diagram
May 12, 2015
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Micrel, Inc.
MIC4608
Functional Diagram
May 12, 2015
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Revision 1.0
Micrel, Inc.
MIC4608
Operational Truth Table
ULVO(6, 7)
Inputs
Outputs(8, 9)
ST
HI
LI
EN
HB
UVLO
VDD
UVLO
HO
LO
Disabled
X
X
X
L
X
X
L
L
VDD UVLO
X
X
X
X
X
L
L
L
VHB UVLO
L
X
L or H
H
L
H
L
L or H
VHB UVLO
H
H or L
X
H
L
H
L
L or H
L
H
H
H
H
L
L
L
H
H
H
L
L
L
L
H
H
H
H
L
H
L
H
L
H
H
H
H
L
(10)
Condition
L
Switching
H
L
H
H
H
H
H
L
H
H
H
L
H
H
(10)
L
H
L
H
H
X
H
H
X
H
H
L
X
H
H
H
L
H
H
H
X
H
H
H
H
L
H
H
Note:
6. UVLO = H when VDD > UVLO Threshold.
7. UVLO = L when VDD < UVLO Threshold.
8. HO and LO remain low if both HI and LI are High when VDD rises above the UVLO threshold or when the EN pin is asserted high. Normal switching
operation begins when one of the inputs changes state from H to L.
9. Anti-shoot-through circuit prevents a high on both outputs simultaneously.
10. Output remains low until the other output transitions from high to low, then the output goes high.
May 12, 2015
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Micrel, Inc.
MIC4608
Typical Characteristics
VDD Quiescent Current
vs. Temperature
VDD Quiescent Current
vs. VDD Voltage
60
125°C
EN=VDD
50
40
30
25°C
-40°C
20
50
VHS = GND
VDD = 20V
EN = VDD
50
VHB QUIESCENT CURRENT (µA)
VHS=GND
VDD QUIESCENT CURRENT (µA)
40
VDD = 12V
30
20
VDD = 10V
10
10
10
12
14
16
18
VHS=GND
EN=VDD
40
30
-25
0
25
50
75
125
100
10
40
30
VHB = 12V
20
VHB = 10V
50
75
100
90
125ºC
80
-40ºC
70
60
50
25ºC
40
30
5
TEMPERATURE (°C)
VHB Operating Current
vs. Frequency
160
-40ºC
140
25ºC
120
100
80
60
40
125ºC
20
0
0
5
10
15
FREQUENCY (kHz)
May 12, 2015
150
20
20
-40ºC
140
125ºC
130
120
110
25ºC
100
90
80
70
60
50
10
15
0
20
5
320
300
280
260
240
220
200
180
160
140
120
100
80
60
40
20
10
15
20
FREQUENCY (kHz)
HO Output Sink/Source
On-Resistance vs. Temperature
VHB Operating Current
vs. Frequency
VHB OPERATING CURRENT (µA)
VDD = 12V
VHB = 12V
CLOAD=0nF
180
VDD = 20V
VHB = 20V
CLOAD=0nF
160
FREQUENCY (kHz)
200
18
40
0
125
16
170
VDD = 12V
VHB = 12V
CLOAD=0nF
20
10
25
14
VDD Operating Current
vs. Frequency
VDD OPERATING CURRENT (µA)
VDD OPERATING CURRENT (µA)
VHB QUIESCENT CURRENT (µA)
VHB = 20V
0
12
VHB (V)
100
VHS = GND
-25
-40°C
VDD Operating Current
vs. Frequency
50
-50
25°C
20
TEMPERATURE (°C)
VHB Quiescent Current
vs. Temperature
EN = VDD
125°C
10
-50
20
VDD (V)
20
IHO = 50mA
VDD = 20V
VHB = 20V
CLOAD=0nF
VHS = GND
-40ºC
VHB = VDD = VEN
VDD = 12V
15
ON RESISTANCE (Ω)
VDD QUIESCENT CURRENT (µA)
60
VHB OPERATING CURRENT (µA)
VHB Quiescent Current
vs. VHB Voltage
25ºC
125ºC
10
VDD = 20V
5
0
0
5
10
15
FREQUENCY (kHz)
8
20
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
Revision 1.0
Micrel, Inc.
MIC4608
Typical Characteristics (Continued)
Input to Output Propagation
Delay (ST = Low) vs. VDD Voltage
LO Output Sink/Source
On-Resistance vs. Temperature
500
20
500
ILO=50mA
VHS=GND
490
VDD = 12V
VHB=VDD=VEN
15
TA = 25°C
VHS = 0V
VST = 0V
CLOAD = 1.3nF
VDD= 12V
VHS = 0V
VST=0V
CLOAD=1.3nF
490
DELAY (ns)
480
DELAY (ns)
ON RESISTANCE (Ω)
Input to Output Propagation
Delay (ST=Low) vs. Temperature
470
10
VDD = 20V
480
460
5
470
450
440
0
0
25
50
75
100
460
12
10
125
14
TEMPERATURE (°C)
Input to Output Propagation Delay
(ST=High) vs. VDD Voltage
18
20
1000
850
950
DELAY (ns)
600
TA = 25°C
VHS = 0V
VST=VDD
CLOAD=1.3nF
550
500
650
HI Fall to HO Fall
500
450
400
400
12
HI Rise to LO Fall
550
HI Fall to HO Fall
450
10
HI Fall to LO Rise
700
600
14
16
18
-25
0
VDD (V)
4900
4800
4700
4600
4500
4400
4300
4200
4100
PROPAGATION DELAYY (ns)
5000
PROPOGATION DELAY (ns)
25
50
75
100
-25
0
25
50
75
TEMPERATURE (°C)
May 12, 2015
4000
3500
3000
2500
10
12
14
100
125
16
18
20
VDD (V)
Enable Turn-Off Propagation
Delay vs. Temperature
700
TA = 25°C
VHS = 0V
VST = 0V
CLOAD = 1.3nF
680
660
640
620
600
580
560
VDD = 12V
VHS = 0V
VST = 0V
CLOAD = 1.3nF
690
680
670
660
650
640
630
540
4000
125
4500
125
700
VDD = 12V
VHS = 0V
VST = 0V
CLOAD = 1.3nF
-50
5000
Enable Turn-Off Propagation
Delay vs. VDD
EN Turn-On Propagation Delay
vs. Temperature
5100
100
TA = 25°C
VHS = 0V
VST = 0V
CLOAD = 1.3nF
TEMPERATURE (°C)
5200
75
2000
-50
20
50
5500
800
750
25
6000
PROPOGATION DELAY (ns)
DELAY (ns)
HI Fall to LO Rise
650
0
Enable Turn-On Propagation
Delay vs. VDD
850
750
HI Rise to LO Fall
-25
TEMPERATURE (°C)
VDD= 12V
VHS = 0V
HI Rise to HO Rise V =V
ST
DD
CLOAD=1.3nF
900
HI Rise to HO Rise
700
-50
Input to Output Propagation
Delay (ST=High) vs. Temperature
900
800
16
VDD (V)
PROPOGATION DELAY (ns)
-25
-50
10
12
14
VDD (V)
9
16
18
20
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
Revision 1.0
Micrel, Inc.
MIC4608
Typical Characteristics (Continued)
260
80
VHS = 0V
VST = 0V
CLOAD = 1.3nF
75
70
400
VHS = 0V
CLOAD=1.3nF
250
240
360
230
60
55
50
45
25°C
40
220
25°C
210
200
125°C
190
35
180
30
-40°C
25
160
10
12
14
VDD (V)
May 12, 2015
16
18
20
320
300
25°C
280
260
125°C
240
170
20
-40°C
340
DEAD TIME (ns)
125°C
VHS = 0V
CLOAD=1.3nF
380
-40°C
65
tFLTR (ns)
TRANSITION TIME (ns)
Dead Time
vs. VDD Voltage
Input Filter Time
vs. VDD Voltage
HO/LO Rise Time and Fall Time
220
10
12
14
16
VDD (V)
10
18
20
10
12
14
16
18
20
VDD (V)
Revision 1.0
Micrel, Inc.
MIC4608
Functional Description
The MIC4608 is a 600V half-bridge driver designed to
drive both high-side and low-side IGBTs or MOSFETs.
Minimum input pulse width filters and anti-shoot-through
logic circuitry improve the driver’s noise immunity. A
STATE pin allows either a single input or two
independent inputs to control both FETs.
Startup and UVLO Circuitry
The VDD pins supply power directly to the low-side gate
driver and to the high-side driver through an external
bootstrap diode. VDD also supplies power to the internal
logic and control circuitry.
Figure 3. Input Stage
An internal pull-down resistor is connected to the HI and
LI pins. This keeps the driver output pins low if the inputs
are disconnected or left floating. A small amount of
hysteresis is programmed into the input to prevent false
triggering of the output. In addition, there is a minimum
pulse width filter on the HI and LI inputs for additional
noise immunity protection. The input pulse width must
exceed the TFLTR time before the outputs will change
state. Refer to the Electrical Characteristics table and
Figure 1 for additional information.
The high-side and low-side drivers each have a separate
UVLO circuit that force the driver output low until the
supply voltage exceeds the UVLO threshold. The lowside UVLO circuit monitors the voltage between the VDD
and VSS pins. The high-side UVLO circuit monitors the
voltage between the HB and HS pins. Hysteresis in the
UVLO circuits prevents noise and finite circuit impedance
from causing chatter during turn-on.
Low-Side Driver
The low-side driver is designed to drive a ground (VSS
pin) referenced N-channel MOSFET or IGBT. Low driver
impedances allow the external IGBT to be turned on and
off quickly. The rail-to-rail drive capability of the output
ensures a low RDSON from the external power device.
Refer to the low-side driver block diagram in the
Functional Diagram section for further details.
State Pin (ST)
The state pin configures the driver for single (PWM) input
or independent (HI/LI) input operation. Setting the ST pin
low allows the HO and LO outputs to be independently
controlled by the HI and LI pins, respectively. Setting the
ST pin high will disable the LI input. The HO and LO pins
are controlled by the HI pin.
The dead time is
automatically added between the HO and LO outputs in
this mode.
When driving the external IGBT on, the driver’s Pchannel MOSFFET is turned on and VDD is applied to the
external IGBT’s gate. To turn off the external IGBT, the
driver’s N-channel FET is turned on, which will discharge
the external IGBT’s gate to ground.
In either mode, the internal anti-shoot-through circuitry
prevents overlap of the HO and LO signals. An internal
pull-down resistor is connected from the ST pin to VSS.
Enable Pin (EN)
Setting the EN pin low puts the device into a low IQ state
and turns off both the LO and HO outputs. A high level
on the EN pin turns on the internal bias in the driver and
allows the driver to operate normally. An internal pulldown resistor is connected from the EN pin to VSS.
Input Stage
The HI and LI pins are referenced to the VSS pin and
have a CMOS/TTL compatible input range. The input
threshold voltage is independent of the VDD supply. The
input voltage must not exceed the VDD pin voltage. The
voltage state of the input signal(s) does not change the
quiescent current draw of the driver.
The input stage block diagram is shown in Figure 3.
Figure 4. Low-Side Block Diagram
May 12, 2015
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Micrel, Inc.
MIC4608
High-Side Driver and Bootstrap Circuit
A block diagram of the high-side driver and bootstrap
circuit is shown in Figure 5. This driver is designed to
drive a floating N-channel FET or IGBT, whose
source/emitter terminal is referenced to the HS pin.
Figure 6. MIC4608 Driving a Motor
Figure 5. High-Side Driver and Bootstrap Circuit
Block Diagram
A low-power, high-speed, level-shifting circuit isolates the
low side (VSS pin) referenced circuitry from the high-side
(HS pin) referenced driver. Power to the high-side driver
and UVLO circuit is supplied by the bootstrap circuit while
the voltage level of the HS pin is shifted high.
The bootstrap circuit consists of an external diode and
capacitor, CB. In a typical application, such as the motor
drive circuit shown in Figure 6, the HS pin is at ground
potential while the low-side IGBT is on. The diode allows
capacitor CB to charge up to VDD-VF during this time
(where VF is the diode’s forward voltage drop). When the
high-side IGBT is ready to turn on, the voltage across
capacitor CB is applied to the IGBT’s gate. As the upper
IGBT turns on, voltage on the HS pin rises with the
emitter of the high-side IGBT until it reaches VIN. As the
HS and HB pins rise, the internal diode is reverse biased
preventing capacitor CB from discharging.
May 12, 2015
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Micrel, Inc.
MIC4608
Application Information
HS Node Clamp
A resistor/diode clamp between the switching node and
the HS pin is recommended to minimize large negative
glitches or pulses on the HS pin.
Bootstrap Circuit
Figure 8 shows the high-side and low-side IGBTs in on
and off mode, which regulate the speed of the motor.
There is a brief period of time (dead time) between
switching to prevent both IGBTs from being on at the same
time. When the high-side IGBT is conducting during the
on-time state, current flows into the motor. After the highside IGBT turns off, but before the low-side IGBT turns on,
current from the motor flows through the diode in parallel
with the low-side IGBT. Depending upon the turn-on time
of the diode, the motor current, and circuit parasitics, the
initial negative voltage on the switch node can be several
volts or more. The forward voltage drop of the diode can
be several volts, depending on the diode and motor
current.
Even though the HS pin is rated for negative voltage, it is
good practice to clamp the negative voltage on the HS pin
with a resistor and diode to prevent excessive negative
voltage from damaging the driver. Depending upon the
application and amount of negative voltage on the switch
node, a 1A fast recovery diode and minimum 10 ohm
resistor are recommended. The diode reverse voltage
must be greater than the high-voltage input supply (VIN).
Larger values of resistance can be used if necessary.
Figure 7. Bootstrap Circuit
Figure 7 shows the bootstrap circuit, where the capacitor
voltage drops each time it delivers charge to turn on the
IGBT. The voltage drop depends on the gate charge
required by the IGBT. Most IGBT and MOSFET
specifications contain a gate charge versus VGE or VGS
voltage information or graphs. Based on this information
and a recommended ΔVHB of less than 0.1V, the minimum
value of bootstrap capacitance is calculated as:
CB ≥
Q gate
∆VHB
Adding a series resistor in the switch node limits the peak
high-side driver current during turn-off, which affects the
switching speed of the high-side driver. The resistor in
series with the HO pin may be reduced to help
compensate for the extra HS pin resistance.
Eq. 1
Where:
Qgate = total gate charge at VHB
∆VHB = voltage drop at the HB pin
The decoupling capacitor for the VDD input may be
calculated in with the same formula; however, the two
capacitors are usually equal in value.
Figure 8. Negative HS Pin Voltage
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MIC4608
Power Dissipation Considerations
Power dissipation in the driver can be separated into two
areas:
•
Gate driver dissipation
•
Quiescent current dissipation used to supply the
internal logic and control functions.
Gate Driver Power Dissipation
Power dissipation in the output driver stage is mainly
caused by charging and discharging the gate to emitter
and gate to collector capacitance of the external IGBT.
Figure 9 shows a simplified equivalent circuit of the
MIC4608 driving an external high-side IGBT.
Figure 10. Typical Gate Charge vs. VGE
PDRIVER = Q G × VGE × fS
Eq. 2
Where:
PDRIVER = Average drive circuit power due to switching
QG = Total gate charge at VGE
VGE = Gate to emitter voltage on the IGBT
fS = Switching frequency of the gate drive circuit
The power dissipated by each of the internal gate drivers
(high-side or low-side) is equal to the ratio of RON and ROFF
to the external resistive losses in RG and RG_INT. Letting
RON = ROFF, the power dissipated in either the high or low
driver in the MIC4608 due to driving the external IGBT is:
Figure 9. MIC4608 High-Side Driving and External IGBT
Dissipation during External IGBT/MOSFET Turn-On
Energy from capacitor CB is used to charge up the input
capacitance of the IGBT (CGE and CGC). The energy
delivered to the gate is dissipated in the three resistive
components, RON, RG and RG_INT. RG is the series resistor
(if any) between the driver IC and the IGBT. RG_INT is the
gate resistance of the IGBT. RG_INT is usually listed in the
IGBT or MOSFET specifications. The ESR of capacitor CB
and the resistance of the connecting etch can be ignored
since they are much less than RON and RG_INT.
Pdiss HS(LS) = PDRIVER
R ON
R ON + R G + R G_INT
The total power dissipated is equal to the sum of the highside and low-side driver dissipations.
Supply Current Power Dissipation
Power is dissipated in the MIC4608 even if nothing is
being driven. The supply current is drawn by the bias for
the internal circuitry, the level shifting circuitry, and shootthrough current in the output drivers. The supply current is
proportional to operating frequency and the VDD and VHB
voltages. The Typical Characteristics graphs show how
supply current varies with switching frequency and supply
voltage.
The effective capacitances of CGE and CGC are difficult to
calculate because they vary non-linearly with IC, VGE, and
VCE. Fortunately, most power IGBT and MOSFET
specifications include a graph of total gate charge versus
VGE. Figure 10 shows a typical gate charge curve for an
arbitrary IGBT. This chart shows that for a gate voltage of
12V, the IGBT requires 12nC of charge. The power
dissipated by the resistive components of the gate drive
circuit during turn-on is calculated as:
The power dissipated by the MIC4608 due to supply
current is:
Pdiss SUPPLY = VDD × IDD + VHB × IHB
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Eq. 3
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MIC4608
Total Power Dissipation and Thermal Considerations
Total power dissipation in the MIC4608 is equal to the
power dissipation caused by driving the external IGBTs
and the supply current.
Placement of the decoupling capacitors is critical. The
bypass capacitor for VDD should be placed as close as
possible between the VDD and VSS pins. The bypass
capacitor (CB) for the HB supply pin must be located as
close as possible between the HB and HS pins. The etch
connections must be short, wide, and direct. The use of a
ground plane to minimize connection impedance is
recommended. Refer to the section “Grounding,
Component Placement and Circuit Layout” for more
information.
Pdiss TOTAL = Pdiss SUPPLY + PdissDRIVE(HS ) + PdissDRIVE(LS )
Eq. 5
The die temperature can be calculated after the total
power dissipation is known.
Eq. 6
TJ = TA + Pdiss TOTAL × θ JA
Where:
TA = maximum ambient temperature
TJ = junction temperature (°C)
PdissTOTAL = power dissipation of the MIC4608
θJA = thermal resistance from junction to ambient air
Grounding, Component Placement and Circuit Layout
Nanosecond switching speeds and ampere peak currents
in and around the MIC4608 driver requires proper
placement and trace routing of all components. Improper
placement may cause degraded noise immunity, false
switching, excessive ringing, or circuit latch-up.
Other Timing Considerations
Make sure the input signal pulse width is greater than the
minimum specified pulse width. An input signal that is less
than the minimum pulse width may result in no output
pulse or an output pulse whose width is significantly less
than the input.
Figure 11 shows the critical current paths when the driver
outputs go high and turn on the external IGBTs. It also
helps demonstrate the need for a low impedance ground
plane. Charge needed to turn-on the IGBT gates comes
from the decoupling capacitors CVDD and CB. Current in the
low-side gate driver flows from CVDD through the internal
driver, into the IGBT gate, and out the emitter. The return
connection back to the decoupling capacitor is made
through the ground plane. Any inductance or resistance in
the ground return path causes a voltage spike or ringing to
appear on the emitter of the IGBT. This voltage works
against the gate drive voltage and can either slow down or
turn off the IGBT during the period when it should be
turned on.
The maximum duty cycle (ratio of high side on-time to
switching period) is controlled by the minimum pulse width
of the low side and by the time required for the CB
capacitor to charge during the off-time. Adequate time
must be allowed for the CB capacitor to charge up before
the high-side driver is turned on.
Decoupling and Bootstrap Capacitor Selection
Decoupling capacitors are required for both the low side
(VDD) and high side (HB) supply pins. These capacitors
supply the charge necessary to drive the external IGBTs
and MOSFETs and also minimize the voltage ripple on
these pins. The capacitor from HB to HS has two
functions: it provides decoupling for the high-side circuitry
and also provides current to the high-side circuit while the
high-side external IGBT/MOSFET is on. Ceramic
capacitors are recommended because of their low
impedance and small size. Z5U type ceramic capacitor
dielectrics are not recommended because of the large
change in capacitance over temperature and voltage. A
minimum value of 0.1µF is required for each of the
capacitors, regardless of the IGBT/MOSFETs being
driven. Larger IGBT/MOSFETs and low switching
frequencies may require larger capacitance values for
proper operation. The voltage rating of the capacitors
depends on the supply voltage, ambient temperature and
the voltage derating used for reliability. 25V rated X5R or
X7R ceramic capacitors are recommended for most
applications. The minimum capacitance value should be
increased if low voltage capacitors are used because even
good quality dielectric capacitors, such as X5R, will lose
40% to 70% of their capacitance value at the rated
voltage.
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Current in the high-side driver is sourced from capacitor CB
and flows into the HB pin and out the HO pin, into the gate
of the high side IGBT. The return path for the current is
from the emitter of the IGBT and back to capacitor CB. The
high-side circuit return path usually does not have a lowimpedance ground plane so the etch connections in this
critical path should be short and wide to minimize parasitic
inductance. As with the low-side circuit, impedance
between the IGBT emitter and the decoupling capacitor
causes negative voltage feedback that fights the turn-on of
the IGBT.
It is important to note that capacitor CB must be placed
close to the HB and HS pins. This capacitor not only
provides all the energy for turn-on but it must also keep HB
pin noise and ripple low for proper operation of the highside drive circuitry.
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MIC4608
Figure 11. Turn-On Current Paths
Figure 12 shows the critical current paths when the driver
outputs go low and turn off the external IGBTs. Short, lowimpedance connections are important during turn-off for
the same reasons given in the turn-on explanation. Current
flowing through the internal diode replenishes charge in
the bootstrap capacitor, CB.
Figure 12. Turn-Off Current Paths
Use the following layout guidelines for optimum circuit
performance:
Use a ground plane to minimize parasitic inductance and
impedance of the return paths. The MIC4608 is capable of
greater than 1A peak currents and any impedance
between the MIC4608, the decoupling capacitors, and the
external IGBT/MOSFET will degrade the performance of
the driver.
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MIC4608
Typical Application Schematic
Bill of Materials
Item
Part Number
C1
No Fill
Manufacturer
CKG57NX7T2J105M500JH
TDK
C10
SK100M450ST
Cornell
Dubilier(12)
C3
EEE-FK1V330P
Panasonic
C4, C6, C9
C2012X7S2A105K125AE
TDK
C5
C2012X7R2A102M085AA
TDK
US1M-E3
Qty.
0
(11)
C2, C7
D1, D2, D3, D4
Description
(13)
(14)
Vishay
(15)
1µF, 630V, X7T, Ceramic Capacitor
2
10µF, 450V, Aluminum Electrolytic
1
33µF, 35V, Aluminum Electroltyic
1
1µF, 100V, X7S, 0805
3
1nF, 100V, X7R, 0805
1
1A, 1kV, Fast Recovery Diode
4
Q1, Q2
IRG4RC10UDTRLP
IR
IGBT, 600V, 8.5A, DPAK
2
R1, R2, R14
CRCW060310R0FRT1
Vishay Dale
10Ω (0603 size), 1%
4
R3
No Fill
R6, R7
CRCW0600000FRT1
Vishay Dale
0Ω (0603 size)
2
R8, R9, R10, R13
CRCW06031002FRT1
Vishay Dale
10kΩ (0603 size), 1%
4
600V Half Bridge MOSFET or IGBT Driver
1
U1
MIC4608YM
0
Micrel
(16)
Notes:
11. TDK: www.tdk.com.
12. Cornell Dubilier: www.cde.com.
13. Panasonic: www.panasonic.com.
14. Vishay: www.vishay.com.
15. IR: www.IRF.com.
16. Micrel, Inc.: www.micrel.com.
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MIC4608
PCB Layout Recommendations
Top Layer
Bottom Layer
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MIC4608
Package Information and Recommended Landing Pattern(17)
14-Pin SOIC (M)
Note:
17. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com.
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Micrel, Inc.
MIC4608
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
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markets. The Company’s products include advanced mixed-signal, analog & power semiconductors; high-performance communication, clock
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Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this datasheet. This
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specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
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