DATASHEET

High-Frequency 6A Sink Synchronous MOSFET Drivers
with Protection Features
ISL6615A
Features
The ISL6615A is a high-speed MOSFET driver optimized to drive
upper and lower power N-Channel MOSFETs in a synchronous
rectified buck converter topology. This driver, combined with an
Intersil Digital or Analog multiphase PWM controller, forms a
complete high frequency and high efficiency voltage regulator.
• Dual MOSFET Drives for Synchronous Rectified Bridge
The ISL6615A drives both upper and lower gates over a range of
4.5V to 13.2V. This drive-voltage provides the flexibility necessary
to optimize applications involving trade-offs between gate charge
and conduction losses.
The ISL6615A features 6A typical sink current for the low-side
gate driver, enhancing the lower MOSFET gate hold-down
capability during PHASE node rising edge, preventing power loss
caused by the self turn-on of the lower MOSFET due to the high
dV/dt of the switching node.
An advanced adaptive zero shoot-through protection is integrated
to prevent both the upper and lower MOSFETs from conducting
simultaneously and to minimize the dead-time. The ISL6615A
includes an overvoltage protection feature operational before
VCC exceeds its turn-on threshold, at which the PHASE node is
connected to the gate of the low side MOSFET (LGATE). The
output voltage of the converter is then limited by the threshold of
the low side MOSFET, which provides some protection to the load
if the upper MOSFET(s) is shorted.
The ISL6615A also features an input that recognizes a
high-impedance state, working together with Intersil multiphase
PWM controllers to prevent negative transients on the controlled
output voltage when operation is suspended. This feature
eliminates the need for the Schottky diode that may be utilized in
a power system to protect the load from negative output voltage
damage.
• Advanced Adaptive Zero Shoot-Through Protection
- Body Diode Detection
- LGATE Detection
- Auto-zero of rDS(ON) Conduction Offset Effect
• Adjustable Gate Voltage for Optimal Efficiency
• 36V Internal Bootstrap Schottky Diode
• Bootstrap Capacitor Overcharging Prevention
• Supports High Switching Frequency (up to 1MHz)
- 6A LGATE Sinking Current Capability
- Fast Rise/Fall Times and Low Propagation Delays
• Support 5V PWM Input Logic
• Tri-State PWM Input for Safe Output Stage Shutdown
• Tri-State PWM Input Hysteresis for Applications with Power
Sequencing Requirement
• Pre-POR Overvoltage Protection
• VCC Undervoltage Protection
• Expandable Bottom Copper PAD for Better Heat Spreading
• Dual Flat No-Lead (DFN) Package
- Near Chip-Scale Package Footprint; Improves PCB Efficiency
and Thinner in Profile
• Pb-free (RoHS compliant)
Applications
• Optimized for POL DC/DC Converters for IBA Systems
• Core Regulators for Intel® and AMD® Microprocessors
• High Current Low-Profile DC/DC Converters
• High Frequency and High Efficiency VRM and VRD
• Synchronous Rectification for Isolated Power Supplies
Related Literature
• Technical Brief TB363 “Guidelines for Handling and Processing
Moisture Sensitive Surface Mount Devices (SMDs)”
• Technical Brief TB389 “PCB Land Pattern Design and Surface
Mount Guidelines for QFN Packages”
April 13, 2012
FN6608.2
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2008, 2010, 2012. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
ISL6615A
Block Diagram
ISL6615A
(UVCC)
BOOT
VCC
UGATE
PRE-POR OVP
FEATURES
+5V
10k
POR/
PWM
PHASE
SHOOTTHROUGH
PROTECTION
(LVCC)
PVCC
UVCC = PVCC
CONTROL
LOGIC
8k
LGATE
GND
SUBSTRATE RESISTANCE
FOR DFN DEVICES, THE PAD ON THE BOTTOM SIDE OF
THE PACKAGE MUST BE SOLDERED TO THE CIRCUIT’S GROUND.
PAD
Typical Application - 2 Channel Converter
VIN
+7V TO +13.2V
+5V
+5V
BOOT
PVCC
FB
COMP
VCC
VCC
VSEN
PWM1
UGATE
PWM
ISL6615A
PHASE
PWM2
PGOOD
LGATE
PWM
CONTROL
(ISL63xx
OR ISL65xx)
GND
ISEN1
VID
(OPTIONAL)
ISEN2
+VCORE
+7V TO +13.2V
PVCC
VIN
BOOT
FS/EN
GND
VCC
UGATE
PWM
ISL6615A
PHASE
LGATE
GND
THE ISL6615A CAN SUPPORT 5V PWM INPUT
2
FN6608.2
April 13, 2012
ISL6615A
Ordering Information
PART NUMBER
(Notes 1, 2, 3)
PART
MARKING
TEMP.
RANGE (°C)
PACKAGE
(Pb-free)
PKG.
DWG. #
ISL6615ACBZ
6615A CBZ
0 to +70
8 Ld SOIC
M8.15
ISL6615ACRZ
615A
0 to +70
10 Ld 3x3 DFN
L10.3x3
ISL6615AIBZ
6615A IBZ
-40 to +85
8 Ld SOIC
M8.15
ISL6615AIRZ
15AI
-40 to +85
10 Ld 3x3 DFN
L10.3x3
ISL6615AFRZ
15AF
-40 to +125
10 Ld 3x3 DFN
L10.3x3
NOTES:
1. Add “-T*” suffix for tape and reel. Please refer to TB347 for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte
tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil Pbfree products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for ISL6615A. For more information on MSL please see techbrief TB363.
Pin Configurations
ISL6615A
(10 LD 3x3 DFN)
TOP VIEW
ISL6615A
(8 LD SOIC)
TOP VIEW
UGATE
1
8
PHASE
BOOT
2
7
PVCC
PWM
3
6
VCC
GND
4
5
LGATE
UGATE
1
BOOT
2
10 PHASE
9 PVCC
GND
N/C
3
PWM
4
7 VCC
GND
5
6 LGATE
8 N/C
*RECOMMEND TO CONNECT PIN 3 TO GND AND PIN 8 TO PVCC
Functional Pin Descriptions
PACKAGE PIN #
SOIC
DFN
PIN
SYMBOL
1
1
UGATE
Upper gate drive output. Connect to gate of high-side power N-Channel MOSFET.
2
2
BOOT
Floating bootstrap supply pin for the upper gate drive. Connect the bootstrap capacitor between this pin and the
PHASE pin. The bootstrap capacitor provides the charge to turn on the upper MOSFET. See the Internal Bootstrap
Device “TIMING DIAGRAM” on page 6 under Description for guidance in choosing the capacitor value.
-
3, 8
N/C
No Connection. Recommend to connect pin 3 to GND and pin 8 to PVCC.
3
4
PWM
The PWM signal is the control input for the driver. The PWM signal can enter three distinct states during operation, see the
“TIMING DIAGRAM” on page 6 section under Description for further details. Connect this pin to the PWM output of the
controller.
4
5
GND
Bias and reference ground. All signals are referenced to this node. It is also the power ground return of the driver.
5
6
LGATE
6
7
VCC
Its operating range is +6.8V to 13.2V. Place a high quality low ESR ceramic capacitor from this pin to GND.
7
9
PVCC
This pin supplies power to both upper and lower gate drives. Its operating range is +4.5V to 13.2V. Place a high quality
low ESR ceramic capacitor from this pin to GND.
8
10
PHASE
Connect this pin to the SOURCE of the upper MOSFET and the DRAIN of the lower MOSFET. This pin provides a return
path for the upper gate drive.
9
11
PAD
FUNCTION
Lower gate drive output. Connect to gate of the low-side power N-Channel MOSFET.
Connect this pad to the power ground plane (GND) via thermally enhanced connection.
3
FN6608.2
April 13, 2012
ISL6615A
Absolute Maximum Ratings
Thermal Information
Supply Voltage (VCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15V
Supply Voltage (PVCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VCC + 0.3V
BOOT Voltage (VBOOT-GND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36V
Input Voltage (VPWM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND - 0.3V to 7V
UGATE. . . . . . . . . . . . . . . . . . . . . . . . . . . . VPHASE - 0.3VDC to VBOOT + 0.3V
. . . . . . . . . . . .VPHASE - 3.5V (<100ns Pulse Width, 2µJ) to VBOOT + 0.3V
LGATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND - 0.3VDC to VPVCC + 0.3V
. . . . . . . . . . . . . . . . .GND - 5V (<100ns Pulse Width, 2µJ) to VPVCC + 0.3V
PHASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND - 0.3VDC to 15VDC
GND - 8V (<400ns, 20µJ) to
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30V (<200ns, VBOOT-GND < 36V))
ESD Ratings
HBM (Tested per JESD22-A114E). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV
MM (Tested per JESD22-A115-A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200V
CDM (Tested per JESD22-C101C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV
Latchup . . . . . . . . . . . . . . . . . . . . . . Tested per JESD78A, Class II at +85°C
Thermal Resistance
θJA (°C/W)
θJC (°C/W)
SOIC Package (Notes 4, 5) . . . . . . . . . . . . . 98
56
DFN Package (Notes 6, 7) . . . . . . . . . . . . . 47
5
Maximum Junction Temperature (Plastic Package) . . . . . . . . . . . .+150°C
Maximum Storage Temperature Range . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Recommended Operating Conditions
Ambient Temperature Range
ISL6615ACRZ, ISL6615ACBZ . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C
ISL6615AIRZ, ISL6615AIBZ . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
ISL6615AFRZ (Note 8). . . . . . . . . . . . . . . . . . . . . . . . . . .-40°C to +125°C
Maximum Operating Junction Temperature . . . . . . . . . . . . . . . . . . .+125°C
VCC Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8V to 13.2V
PVCC Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5V to 12V ±10%
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
4. θJA is measured with the component mounted on a high effective thermal conductivity test board in free air.
5. For θJC, the “case temp” location is taken at the package top center.
6. θJA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
Brief TB379.
7. For θJC, the “case temp” location is the center of the exposed metal pad on the package underside.
8. When using ISL6615AFRZ, care should be taken to minimize power dissipation.
Electrical Specifications
PARAMETER
Recommended Operating Conditions; Boldface limits apply over the operating temperature ranges.
SYMBOL
TEST CONDITIONS
MIN
(Note 9)
TYP
MAX
(Note 9)
UNITS
VCC SUPPLY CURRENT
Bias Supply Current
IVCC
fPWM = 300kHz, VVCC = 12V
-
4.5
-
mA
Gate Drive Bias Current
IPVCC
fPWM = 300kHz, VPVCC = 12V
-
8
-
mA
VCC Rising Threshold
6.1
6.4
6.7
V
VCC Falling Threshold
4.7
5.0
5.3
V
VPWM = 5V
-
510
-
µA
VPWM = 0V
-
-475
-
µA
PWM Rising Threshold (Note 10)
VCC = 12V
-
3.00
-
V
PWM Falling Threshold (Note 10)
VCC = 12V
-
2.00
-
V
Typical Tri-State Shutdown Window
VCC = 12V
1.80
-
2.40
V
POWER-ON RESET AND ENABLE
PWM INPUT (See “TIMING DIAGRAM” on page 6)
Input Current
IPWM
Tri-State Lower Gate Falling Threshold
VCC = 12V
-
1.50
-
V
Tri-State Lower Gate Rising Threshold
VCC = 12V
-
1.00
-
V
Tri-State Upper Gate Rising Threshold
VCC = 12V
-
3.20
-
V
Tri-State Upper Gate Falling Threshold
VCC = 12V
-
2.70
-
V
-
55
-
ns
Shutdown Holdoff Time
tTSSHD
UGATE Rise Time (Note 10)
tRU
VPVCC = 12V, 3nF Load, 10% to 90%
-
13
-
ns
LGATE Rise Time (Note 10)
tRL
VPVCC = 12V, 3nF Load, 10% to 90%
-
10
-
ns
4
FN6608.2
April 13, 2012
ISL6615A
Electrical Specifications
PARAMETER
Recommended Operating Conditions; Boldface limits apply over the operating temperature ranges. (Continued)
SYMBOL
TEST CONDITIONS
MIN
(Note 9)
TYP
MAX
(Note 9)
UNITS
UGATE Fall Time (Note 10)
tFU
VPVCC = 12V, 3nF Load, 90% to 10%
-
10
-
ns
LGATE Fall Time (Note 10)
tFL
VPVCC = 12V, 3nF Load, 90% to 10%
-
10
-
ns
UGATE Turn-On Propagation Delay
(Note 10)
tPDHU
VPVCC = 12V, 3nF Load, Adaptive
-
30
-
ns
LGATE Turn-On Propagation Delay
(Note 10)
tPDHL
VPVCC = 12V, 3nF Load, Adaptive
-
20
-
ns
UGATE Turn-Off Propagation Delay
(Note 10)
tPDLU
VPVCC = 12V, 3nF Load
-
10
-
ns
LGATE Turn-Off Propagation Delay
(Note 10)
tPDLL
VPVCC = 12V, 3nF Load
-
20
-
ns
LG/UG Tri-State Propagation Delay
(Note 10)
tPDTS
VPVCC = 12V, 3nF Load
-
20
-
ns
Upper Drive Source Current
IU_SOURCE
VPVCC = 12V, 3nF Load
-
2.5
-
A
Upper Drive Source Impedance
RU_SOURCE
150mA Source Current
-
1
-
Ω
Upper Drive Sink Current
IU_SINK
VPVCC = 12V, 3nF Load
-
4
-
A
Upper Drive Sink Impedance
RU_SINK
150mA Sink Current
-
0.8
-
Ω
Lower Drive Source Current
IL_SOURCE
VPVCC = 12V, 3nF Load
-
4
-
A
Lower Drive Source Impedance
RL_SOURCE
150mA Source Current
-
0.7
-
Ω
Lower Drive Sink Current
IL_SINK
VPVCC = 12V, 3nF Load
-
6
-
A
Lower Drive Sink Impedance
RL_SINK
150mA Sink Current
-
0.45
-
Ω
OUTPUT (Note 10)
NOTES:
9. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization
and are not production tested.
10. Limits established by characterization and are not production tested.
5
FN6608.2
April 13, 2012
ISL6615A
Description
1.18V < PWM < 2.36V
0.76V < PWM < 1.96V
PWM
tPDLU
tPDHU
tTSSHD
tPDTS
tPDTS
UGATE
tFU
tRU
LGATE
tFL
tRL
tTSSHD
tPDLL
tPDHL
FIGURE 1. TIMING DIAGRAM
Operation
Designed for versatility and speed, the ISL6615A MOSFET driver
controls both high-side and low-side N-Channel FETs of a halfbridge power train from one externally provided PWM signal.
Prior to VCC exceeding its POR level, the Pre-POR overvoltage
protection function is activated during initial start-up; the upper
gate (UGATE) is held low and the lower gate (LGATE), controlled
by the Pre-POR overvoltage protection circuits, is connected to
the PHASE. Once the VCC voltage surpasses the VCC Rising
Threshold (see “Electrical Specifications” on page 4) the PWM
signal takes control of gate transitions. A rising edge on PWM
initiates the turn-off of the lower MOSFET (see “TIMING
DIAGRAM” on page 6). After a short propagation delay [tPDLL],
the lower gate begins to fall. Typical fall times [tFL] are provided
in the “Electrical Specifications” on page 4. Adaptive shootthrough circuitry monitors the LGATE voltage and determines the
upper gate delay time [tPDHU]. This prevents both the lower and
upper MOSFETs from conducting simultaneously. Once this delay
period is complete, the upper gate drive begins to rise [tRU] and
the upper MOSFET turns on.
A falling transition on PWM results in the turn-off of the upper
MOSFET and the turn-on of the lower MOSFET. A short
propagation delay [tPDLU] is encountered before the upper gate
begins to fall [tFU]. Again, the adaptive shoot-through circuitry
determines the lower gate delay time, tPDHL. The PHASE voltage
and the UGATE voltage are monitored, and the lower gate is
allowed to rise after PHASE drops below a level or the voltage of
UGATE to PHASE reaches a level depending upon the current
direction (See the following section titled “Advanced Adaptive
Zero Shoot-Through Dead-Time Control” for details). The lower
gate then rises [tRL], turning on the lower MOSFET.
Advanced Adaptive Zero Shoot-Through
Dead-time Control
The ISL6615A driver incorporates a unique adaptive dead-time
control technique to minimize dead-time, resulting in high
efficiency from the reduced freewheeling time of the lower
MOSFETs’ body-diode conduction, and to prevent the upper and
6
lower MOSFETs from conducting simultaneously. This is
accomplished by ensuring the rising gate turns on its MOSFET
with minimum and sufficient delay after the other has turned off.
During turn-off of the lower MOSFET, the LGATE voltage is
monitored until it drops below 1.75V. Prior to reaching this level,
there is a 25ns blanking period to protect against sudden dips in
the LGATE voltage. Once 1.75V is reached, the UGATE is released
to rise after 20ns of propagation delay. Once the PHASE is high,
the adaptive shoot-through circuitry monitors the PHASE and
UGATE voltages during PWM falling edge and subsequent UGATE
turn-off. If PHASE falls to less than +0.8V, the LGATE is released
to turn on after 10ns of propagation delay. If the UGATE-PHASE
falls to less than 1.75V and after 40ns of propagation delay,
LGATE is released to rise.
Tri-state PWM Input
A unique feature of these drivers and other Intersil drivers is the
addition of a shutdown window to the PWM input. If the PWM
signal enters and remains within the shutdown window for a set
holdoff time, the driver outputs are disabled and both MOSFET
gates are pulled and held low. The shutdown state is removed
when the PWM signal moves outside the shutdown window.
Otherwise, the PWM rising and falling thresholds outlined in
“Electrical Specifications” on page 4, determine when the lower
and upper gates are enabled.
This feature helps prevent a negative transient on the output
voltage when the output is shut down, eliminating the Schottky
diode that is used in some systems for protecting the load from
reversed output voltage events.
In addition, more than 400mV hysteresis also incorporates into
the Tri-State shutdown window to eliminate PWM input
oscillations due to the capacitive load seen by the PWM input
through the body diode of the controller’s PWM output when the
power-up and/or power-down sequence of bias supplies of the
driver and PWM controller are required.
FN6608.2
April 13, 2012
ISL6615A
Power-On Reset (POR) Function
1.6
During initial start-up, the VCC voltage rise is monitored. Once the
rising VCC voltage exceeds 6.4V (typically), operation of the driver
is enabled and the PWM input signal takes control of the gate
drives. If VCC drops below the falling threshold of 5.0V (typically),
operation of the driver is disabled.
Prior to VCC exceeding its POR level, the upper gate is held low
and the lower gate is controlled by the overvoltage protection
circuits. The upper gate driver is powered from PVCC and will be
held low when a voltage of 2.75V or higher is present on PVCC as
VCC surpasses its POR threshold. The PHASE is connected to the
gate of the low side MOSFET (LGATE), which provides some
protection to the microprocessor if the upper MOSFET(s) is
shorted during start-up, normal, or shutdown conditions. For
complete protection, the low side MOSFET should have a gate
threshold well below the maximum voltage rating of the
load/microprocessor.
Internal Bootstrap Device
Both drivers feature an internal bootstrap Schottky diode. Simply
adding an external capacitor across the BOOT and PHASE pins
completes the bootstrap circuit. The bootstrap function is also
designed to prevent the bootstrap capacitor from overcharging
due to the large negative swing at the trailing-edge of the PHASE
node. This reduces voltage stress on the boot to phase pins.
The bootstrap capacitor must have a maximum voltage rating
above PVCC + 5V and its capacitance value can be chosen from
Equation 1:
Q GATE
C BOOT_CAP ≥ --------------------------------ΔV BOOT_CAP
(EQ. 1)
Q G1 • PVCC
Q GATE = ------------------------------- • N Q1
V GS1
where QG1 is the amount of gate charge per upper MOSFET at
VGS1 gate-source voltage and NQ1 is the number of control
MOSFETs. The ΔVBOOT_CAP term is defined as the allowable
droop in the rail of the upper gate drive.
As an example, suppose two IRLR7821 FETs are chosen as the
upper MOSFETs. The gate charge, QG , from the data sheet is
10nC at 4.5V (VGS) gate-source voltage. Then the QGATE is
calculated to be 53nC for PVCC = 12V. We will assume a 200mV
droop in drive voltage over the PWM cycle. We find that a
bootstrap capacitance of at least 0.267µF is required. The next
larger standard value capacitance is 0.33µF. A good quality
ceramic capacitor is recommended.
1.2
CBOOT_CAP (µF)
Pre-POR Overvoltage Protection
1.4
1.0
0.8
0.6
QGATE = 100nC
0.4
50nC
0.2
20nC
0.0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
ΔVBOOT_CAP (V)
FIGURE 2. BOOTSTRAP CAPACITANCE vs BOOT RIPPLE
VOLTAGE
Gate Drive Voltage Versatility
The ISL6615A provides the user with flexibility in choosing the
gate drive voltage for efficiency optimization. The ISL6615A ties
the upper and lower drive rails together. Simply applying a
voltage from +4.5V up to 13.2V on PVCC sets both gate drive rail
voltages simultaneously, while VCC’s operating range is from
+6.8V up to 13.2V.
Power Dissipation
Package power dissipation is mainly a function of the switching
frequency (FSW), the output drive impedance, the external gate
resistance and the selected MOSFET’s internal gate resistance and
total gate charge. Calculating the power dissipation in the driver for
a desired application is critical to ensure safe operation. Exceeding
the maximum allowable power dissipation level will push the IC
beyond the maximum recommended operating junction
temperature of +125°C. The maximum allowable IC power
dissipation for the SO8 package is approximately 800mW at room
temperature, while the power dissipation capacity in the DFN
package (with an exposed heat escape pad) is more than 1.5W. The
DFN package is more suitable for high frequency applications. See
“Layout Considerations” on page 8 for thermal transfer
improvement suggestions. When designing the driver into an
application, it is recommended that the following calculation is used
to ensure safe operation at the desired frequency for the selected
MOSFETs. The total gate drive power losses due to the gate charge
of MOSFETs and the driver’s internal circuitry and their
corresponding average driver current can be estimated with
Equations 2 and 3, respectively:
P Qg_TOT = P Qg_Q1 + P Qg_Q2 + I Q • VCC
(EQ. 2)
Q G1 • PVCC 2
P Qg_Q1 = ----------------------------------- • F SW • N Q1
V GS1
Q G2 • PVCC 2
P Qg_Q2 = ----------------------------------- • F SW • N Q2
V GS2
⎛ Q G1 • PVCC • N Q1 Q G2 • PVCC • N Q2⎞
I DR = ⎜ ------------------------------------------------ + ------------------------------------------------⎟ • F SW + I Q
V GS1
V GS2
⎝
⎠
7
(EQ. 3)
FN6608.2
April 13, 2012
ISL6615A
where the gate charge (QG1 and QG2) is defined at a particular
gate to source voltage (VGS1and VGS2) in the corresponding
MOSFET datasheet; IQ is the driver’s total quiescent current with
no load at both drive outputs; NQ1 and NQ2 are the number of
upper and lower MOSFETs, respectively; PVCC is the drive voltage
for both upper and lower FETs. The IQ*VCC product is the
quiescent power of the driver without capacitive load and is
typically 200mW at 300kHz and VCC = PVCC = 12V.
The total gate drive power losses are dissipated among the
resistive components along the transition path. The drive
resistance dissipates a portion of the total gate drive power
losses; the rest will be dissipated by the external gate resistors
(RG1 and RG2) and the internal gate resistors (RGI1 and RGI2) of
MOSFETs. Figures 3 and 4 show the typical upper and lower gate
drives turn-on transition path. The power dissipation on the driver
can be roughly estimated, as shown in Equation 4.
P DR = P DR_UP + P DR_LOW + I Q • VCC
(EQ. 4)
R HI1
R LO1
⎛
⎞ P Qg_Q1
P DR_UP = ⎜ ----------------------------------- + -------------------------------------⎟ • ------------------2
⎝ R HI1 + R EXT1 R LO1 + R EXT1⎠
Q1
PVCC
Q2
D
CGD
G
RG1
CDS
RGI1
CGS
Q1
S
PHASE
FIGURE 3. TYPICAL UPPER-GATE DRIVE TURN-ON PATH
D
CGD
RLO2
G
RG2
CDS
RGI2
CGS
Q2
S
FIGURE 4. TYPICAL LOWER-GATE DRIVE TURN-ON PATH
8
• Minimize trace inductance, especially on low-impedance lines.
All power traces (UGATE, PHASE, LGATE, GND, PVCC, VCC,
GND) should be short and wide (at least 25 mils). Try to place
power traces on a single layer, otherwise, two vias on
interconnection are preferred where possible. For no
connection (NC) pins on the QFN part, connecting them to the
adjacent net (LGATE2/PHASE2) can reduce trace inductance.
• Avoid routing relatively high impedance nodes (such as PWM
and ENABLE lines) close to high dV/dt UGATE and PHASE
nodes.
In addition, for heat spreading, place copper underneath the IC
whether it has an exposed pad or not. The copper area can be
extended beyond the bottom area of the IC and/or connected to
buried power ground plane(s) with thermal vias. This
combination of vias for vertical heat escape, extended copper
plane, and buried planes for heat spreading allows the IC to
achieve its full thermal potential.
Upper MOSFET Self Turn-On Effects at
Start-up
PVCC
RHI2
• Keep decoupling loops (VCC-GND, PVCC-GND and BOOT-PHASE)
short and wide (at least 25 mils). Avoid using vias on decoupling
components other than their ground terminals, which should be
on a copper plane with at least two vias.
• Minimize the current loop of the output and input power trains.
Short the source connection of the lower MOSFET to ground as
close to the transistor pin as feasible. Input capacitors
(especially ceramic decoupling) should be placed as close to
the drain of upper and source of lower MOSFETs as possible.
BOOT
RLO1
The parasitic inductances of the PCB and of the power devices’
packaging (both upper and lower MOSFETs) can cause serious
ringing, exceeding the absolute maximum ratings of the devices.
A good layout helps reduce the ringing on the switching node
(PHASE) and significantly lowers the stress applied to the output
drives. The following advice is meant to lead to an optimized
layout and performance:
• Minimize the inductance of the PHASE node. Ideally, the
source of the upper and the drain of the lower MOSFET should
be as close as thermally allowable.
R GI2
R EXT2 = R G2 + -----------N
RHI1
Layout Considerations
• Shorten all gate drive loops (UGATE-PHASE and LGATE-GND)
and route them closely spaced.
R HI2
R LO2
⎛
⎞ P Qg_Q2
P DR_LOW = ⎜ ----------------------------------- + -------------------------------------⎟ • ------------------R
+
R
R
+
R
2
⎝ HI2
EXT2
LO2
EXT2⎠
R GI1
R EXT1 = R G1 + -----------N
Application Information
Should the driver have insufficient bias voltage applied, its
outputs are floating. If the input bus is energized at a high dV/dt
rate while the driver outputs are floating due to the self-coupling
via the internal CGD of the MOSFET, the UGATE could
momentarily rise up to a level greater than the threshold voltage
of the MOSFET. This could potentially turn on the upper switch
and result in damaging inrush energy. Therefore, if such a
situation (when input bus powered up before the bias of the
controller and driver is ready) could conceivably be encountered,
it is a common practice to place a resistor (RUGPH) across the
gate and source of the upper MOSFET to suppress the Miller
coupling effect. The value of the resistor depends mainly on the
input voltage’s rate of rise, the CGD/CGS ratio, as well as the
FN6608.2
April 13, 2012
ISL6615A
VIN
BOOT
D
CBOOT
CGD
DU
DL
UGATE G
RUGPH
The coupling effect can be roughly estimated with the formulas
in Equation 5, which assume a fixed linear input ramp and
neglect the clamping effect of the body diode of the upper drive
and the bootstrap capacitor. Other parasitic components such as
lead inductances and PCB capacitances are also not taken into
account. These equations are provided for guidance purpose
only. Therefore, the actual coupling effect should be examined
using a very high impedance (10MΩ or greater) probe to ensure
a safe design margin.
PVCC
ISL6615A
gate-source threshold of the upper MOSFET. A higher dV/dt, a
lower CDS/CGS ratio, and a lower gate-source threshold upper
FET will require a smaller resistor to diminish the effect of the
internal capacitive coupling. For most applications, the
integrated 20kΩ typically sufficient, not affecting normal
performance and efficiency.
CDS
RGI
CGS
QUPPER
S
PHASE
FIGURE 5. GATE-TO-SOURCE RESISTOR TO REDUCE UPPER
MOSFET MILLER COUPLING
–V
DS
⎛
-------------------------------⎞
dV
⎜
-----⋅ R ⋅ C iss⎟
dV
⎟
V GS_MILLER = ------ ⋅ R ⋅ C rss ⎜ 1 – e dt
⎜
⎟
dt
⎜
⎟
⎝
⎠
R = R UGPH + R GI
C rss = C GD
9
(EQ. 5)
C iss = C GD + C GS
FN6608.2
April 13, 2012
ISL6615A
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to web to make
sure you have the latest Rev.
DATE
REVISION
5/16/11
FN6608.2
7/21/10
4/20/10
Converted to new template
Added Tjc and applicable note to “Thermal Information” on page 4 for SOIC package.
Updated “Package Outline Drawing” on page 12 (M8.15) to new POD format by removing table and moving
dimensions onto drawing and adding land pattern
Added “ESD Ratings” and “Latchup Tested per JESD78A, Class II at +85°C” to page 4.
FN6608.1
2/24/10
04/30/08
CHANGE
Electrical Specifications Table changes:
PWM Input - Shutdown Holdoff Time - Typ from “65” to “55”
UGATE Turn-On Propagation Delay (Note 10) tPDHU VPVCC = 12V, 3nF Load, Adaptive - from “10” to “30” - ns
LGATE Turn-On Propagation Delay (Note 10) tPDHL VPVCC = 12V, 3nF Load, Adaptive - from “10” to “20” - ns
LGATE Turn-Off Propagation Delay (Note 10) tPDLL VPVCC = 12V, 3nF Load, Adaptive - from “10” to “20” - ns
LG/UG Tri-State Propagation Delay (Note 10) tPDTS VPVCC = 12V, 3nF Load, Adaptive - from “10” to “20” - ns
Converted to New Intersil Template.
Updated Ordering Information Industrial parts Temp Range from "-40C to +70C" to "-40C to +85C".
Added MSL Note to Ordering Information.
Updated Thermal Information Tja and Tjc for SOIC - from "100, N/A" to "98, N/A" DFN - "48, 7" to "47, 5".
Moved over-temp note from conditions of Electrical Specifications table to end of table as "Note".
Added Bold text to conditions of Electrical Specifications table indicating over-temp.
Added note to Min and Max columns of Electrical Specifications table.
Changed layout to meet new standard flow.
Added part # ISL6615AFRZ with temp range of -40°C to +125°C to Ordering Information, Recommended
Operating Conditions and Note 8 reference.
Updated POD L10.3x3 to latest revision.
POD changes are as follows:
Changed Note 4 from "Dimension b applies..." to "Lead width applies..."
Changed Note callout in Detail X from 4 to 5
Changed height in side view from 0.90 MAX to 1.00 MAX
Added Note 4 callout next to lead width in Bottom View
In Land Pattern, corrected lead shape for 4 corner pins to "L" shape (was rectangular and did not match bottom
view).
FN6608.0
Initial Release to web
Products
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*For a complete listing of Applications, Related Documentation and Related Parts, please see the respective device information page
on intersil.com: ISL6615A
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Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time
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10
FN6608.2
April 13, 2012
ISL6615A
Package Outline Drawing
L10.3x3
10 LEAD DUAL FLAT PACKAGE (DFN)
Rev 6, 09/09
3.00
6
PIN #1 INDEX AREA
A
B
1
6
PIN 1
INDEX AREA
(4X)
3.00
2.00
8x 0.50
2
10 x 0.23
4
0.10
1.60
TOP VIEW
10x 0.35
BOTTOM VIEW
4
(4X)
0.10 M C A B
0.415
PACKAGE
OUTLINE
0.200
0.23
0.35
(10 x 0.55)
SEE DETAIL "X"
(10x 0.23)
1.00
MAX
0.10 C
BASE PLANE
2.00
0.20
C
SEATING PLANE
0.08 C
SIDE VIEW
(8x 0.50)
C
0.20 REF
5
1.60
0.05
TYPICAL RECOMMENDED LAND PATTERN
DETAIL "X"
NOTES:
1.
Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2.
Dimensioning and tolerancing conform to AMSE Y14.5m-1994.
3.
Unless otherwise specified, tolerance : Decimal ± 0.05
4.
Lead width applies to the metallized terminal and is measured
between 0.18mm and 0.30mm from the terminal tip.
5.
Tiebar shown (if present) is a non-functional feature.
6.
The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 indentifier may be
either a mold or mark feature.
11
FN6608.2
April 13, 2012
ISL6615A
Package Outline Drawing
M8.15
8 LEAD NARROW BODY SMALL OUTLINE PLASTIC PACKAGE
Rev 3, 3/11
DETAIL "A"
1.27 (0.050)
0.40 (0.016)
INDEX
6.20 (0.244)
5.80 (0.228)
AREA
0.50 (0.20)
x 45°
0.25 (0.01)
4.00 (0.157)
3.80 (0.150)
1
2
8°
0°
3
0.25 (0.010)
0.19 (0.008)
SIDE VIEW “B”
TOP VIEW
2.20 (0.087)
SEATING PLANE
5.00 (0.197)
4.80 (0.189)
1.75 (0.069)
1.35 (0.053)
1
8
2
7
0.60 (0.023)
1.27 (0.050)
3
6
4
5
-C-
1.27 (0.050)
0.51(0.020)
0.33(0.013)
SIDE VIEW “A
0.25(0.010)
0.10(0.004)
5.20(0.205)
TYPICAL RECOMMENDED LAND PATTERN
NOTES:
1. Dimensioning and tolerancing per ANSI Y14.5M-1982.
2. Package length does not include mold flash, protrusions or gate burrs.
Mold flash, protrusion and gate burrs shall not exceed 0.15mm (0.006
inch) per side.
3. Package width does not include interlead flash or protrusions. Interlead
flash and protrusions shall not exceed 0.25mm (0.010 inch) per side.
4. The chamfer on the body is optional. If it is not present, a visual index
feature must be located within the crosshatched area.
5. Terminal numbers are shown for reference only.
6. The lead width as measured 0.36mm (0.014 inch) or greater above the
seating plane, shall not exceed a maximum value of 0.61mm (0.024 inch).
7. Controlling dimension: MILLIMETER. Converted inch dimensions are not
necessarily exact.
8. This outline conforms to JEDEC publication MS-012-AA ISSUE C.
12
FN6608.2
April 13, 2012