DATASHEET

ISL6614
®
Data Sheet
May 5, 2008
FN9155.5
Dual Advanced Synchronous Rectified
Buck MOSFET Drivers with Protection
Features
Features
The ISL6614 integrates two ISL6613 MOSFET drivers and is
specifically designed to drive two independent power
channels in a Multi-Phase interleaved buck converter
topology. These drivers combined with HIP63xx or ISL65xx
Multi-Phase Buck PWM controllers and N-Channel
MOSFETs form complete core-voltage regulator solutions for
advanced microprocessors.
• Quad N-Channel MOSFET Drives for Two Synchronous
Rectified Bridges
The ISL6614 drives both the upper and lower gates
simultaneously over a range from 5V to 12V. This drive
voltage provides the flexibility necessary to optimize
applications involving trade-offs between gate charge and
conduction losses.
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. These products add 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 microprocessor if the
upper MOSFET(s) is shorted during startup. The overtemperature protection feature prevents failures resulting
from excessive power dissipation by shutting off the outputs
when its junction temperature exceeds +150°C (typically).
The driver resets once its junction temperature returns to
+108°C (typically).
The ISL6614 also features a three-state PWM input which,
working together with Intersil’s multi-phase PWM controllers,
prevents a negative transient on the output voltage when the
output is shut down. This feature eliminates the Schottky
diode that is used in some systems for protecting the load
from reversed output voltage events.
• Pin-to-pin Compatible with HIP6602 SOIC Family for
Better Performance and Extra Protection Features
• Advanced Adaptive Zero Shoot-Through Protection
- Body Diode Detection
- Auto-zero of rDS(ON) Conduction Offset Effect
• Adjustable Gate Voltage (5V to 12V) for Optimal Efficiency
• Internal Bootstrap Schottky Diode
• Bootstrap Capacitor Overcharging Prevention
• Supports High Switching Frequency (up to 1MHz)
- 3A Sinking Current Capability
- Fast Rise/Fall Times and Low Propagation Delays
• Three-State PWM Input for Output Stage Shutdown
• Three-State PWM Input Hysteresis for Applications With
Power Sequencing Requirement
• Pre-POR Overvoltage +Protection
• VCC Undervoltage Protection
• Over-Temperature Protection (OTP) with +42°C Hysteresis
• Expandable Bottom Copper Pad for Enhanced Heat Sinking
• QFN Package:
- Compliant to JEDEC PUB95 MO-220 QFN - Quad Flat
No Leads - Package Outline
- Near Chip Scale Package Footprint, which Improves
PCB Efficiency and has a Thinner Profile
• Pb-free Available (RoHS compliant)
Applications
• Core Regulators for Intel® and AMD® Microprocessors
• High Current DC/DC Converters
• High Frequency and High Efficiency VRM and VRD
Related Literature
• Technical Brief TB363 “Guidelines for Handling and
Processing Moisture Sensitive Surface Mount Devices
(SMDs)”
• Technical Brief 400 and 417 for Power Train Design,
Layout Guidelines, and Feedback Compensation Design
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. 2004, 2005, 2007. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
ISL6614
PWM2
PWM1
VCC
PHASE1
ISL6614CR, ISL6614CRZ, ISL6614IR, ISL6614IRZ
(16 LD QFN)
TOP VIEW
ISL6614CB, ISL6614CBZ, ISL6614IB
(14 LD SOIC)
TOP VIEW
16
15
14
13
PWM1
1
14 VCC
PWM2
2
13 PHASE1
GND
3
12 UGATE1
LGATE1
4
11 BOOT1
PVCC
5
10 BOOT2
PGND
6
9 UGATE2
PVCC 3
10 BOOT2
LGATE2
7
8 PHASE2
PGND 4
9
GND 1
12 UGATE1
LGATE1 2
11 BOOT1
5
6
7
8
NC
LGATE2
PHASE2
NC
GND
UGATE2
Ordering Information
PART NUMBER
PART MARKING
TEMP. RANGE (°C)
PACKAGE
PKG. DWG. #
ISL6614CB*
ISL6614CB
0 to +85
14 Ld SOIC
M14.15
ISL6614CBZ* (Note)
6614CBZ
0 to +85
14 Ld SOIC (Pb-free)
M14.15
ISL6614CBZA* (Note)
6614CBZ
0 to +85
14 Ld SOIC (Pb-free)
M14.15
ISL6614CR*
ISL 6614CR
0 to +85
16 Ld 4x4 QFN
L16.4x4
ISL6614CRZ* (Note)
66 14CRZ
0 to +85
16 Ld 4x4 QFN (Pb-free)
L16.4x4
ISL6614CRZA* (Note)
66 14CRZ
0 to +85
16 Ld 4x4 QFN (Pb-free)
L16.4x4
ISL6614IB*
ISL6614IB
-40 to +85
14 Ld SOIC
M14.15
ISL6614IBZ* (Note)
6614IBZ
-40 to +85
14 Ld SOIC (Pb-free)
M14.15
ISL6614IR*
ISL 6614IR
-40 to +85
16 Ld 4x4 QFN
L16.4x4
ISL6614IRZ* (Note)
66 14IRZ
-40 to +85
16 Ld 4x4 QFN (Pb-free)
L16.4x4
*Add “-T” suffix for tape and reel. Please refer to TB347 for details on reel specifications.
NOTE: 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 Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J
STD-020.
2
FN9155.5
May 5, 2008
ISL6614
Block Diagram
BOOT1
PVCC
VCC
UGATE1
OTP AND
PRE-POR OVP
FEATURES
+5V
SHOOTTHROUGH
PROTECTION
10k
PHASE1
CHANNEL 1
PVCC
PWM1
LGATE1
8k
PGND
CONTROL
LOGIC
+5V
PVCC
PGND
BOOT2
10k
UGATE2
PWM2
SHOOTTHROUGH
PROTECTION
8k
GND
PHASE2
CHANNEL 2
PVCC
LGATE2
PGND
PAD
3
FOR ISL6614CR, THE PAD ON THE BOTTOM SIDE OF
THE QFN PACKAGE MUST BE SOLDERED TO THE CIRCUIT’S GROUND.
FN9155.5
May 5, 2008
ISL6614
Typical Application - 4 Channel Converter Using ISL65xx and ISL6614 Gate Drivers
BOOT1
+12V
+12V
UGATE1
VCC
PHASE1
LGATE1
+5V
DUAL
DRIVER
ISL6614
5V TO 12V
BOOT2
COMP
FB
PVCC
+12V
VCC
VSEN
UGATE2
ISEN1
PGOOD
PWM1
EN
PWM2
VID
MAIN ISEN2
CONTROL
ISL65xx
PWM1
PHASE2
PWM2
LGATE2
GND
PGND
+VCORE
ISEN3
FS/DIS
PWM3
PWM4
GND
BOOT1
+12V
+12V
ISEN4
UGATE1
VCC
PHASE1
LGATE1
DUAL
DRIVER
ISL6614
PVCC
5V TO 12V
BOOT2
+12V
UGATE2
PWM1
PHASE2
PWM2
LGATE2
GND
4
PGND
FN9155.5
May 5, 2008
ISL6614
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 Rating
Human Body Model . . . . . . . . . . . . . . . . . . . . Class I JEDEC STD
Thermal Resistance (Typical) . . . . . . . . . . θJA(°C/W) θJC(°C/W)
SOIC Package (Note 1) . . . . . . . . . . . .
90
N/A
QFN Package (Notes 2, 3). . . . . . . . . .
44
4.5
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. . . . . . . . . . . . . . . . . . .-40°C to +85°C
Maximum Operating Junction Temperature. . . . . . . . . . . . . +125°C
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12V ±10%
Supply Voltage Range, PVCC . . . . . . . . . . . . . . . . 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:
1. θJA is measured with the component mounted on a high effective thermal conductivity test board in free air.
2. 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.
3. For θJC, the “case temp” location is the center of the exposed metal pad on the package underside.
Electrical Specifications
Recommended Operating Conditions, Unless Otherwise Noted.
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
VCC SUPPLY CURRENT
Bias Supply Current
IVCC
fPWM = 300kHz, VPVCC = 12V
-
7.1
-
mA
Gate Drive Bias Current
IPVCC
fPWM = 300kHz, VPVCC = 12V
-
9.7
-
mA
0°C to +85°C
9.35
9.80
10.05
V
-40°C to +85°C
8.35
-
10.05
V
0°C to +85°C
7.35
7.60
8.00
V
-40°C to +85°C
6.35
-
8.00
V
VPWM = 5V
-
450
-
µA
VPWM = 0V
-
-400
-
µA
PWM Rising Threshold
VCC = 12V
-
3.00
-
V
PWM Falling Threshold
VCC = 12V
-
2.00
-
V
Typical Three-State Shutdown Window
VCC = 12V
1.80
-
2.40
V
Three-State Lower Gate Falling Threshold
VCC = 12V
-
1.50
-
V
Three-State Lower Gate Rising Threshold
VCC = 12V
-
1.00
-
V
Three-State Upper Gate Rising Threshold
VCC = 12V
-
3.20
-
V
Three-State Upper Gate Falling Threshold
VCC = 12V
-
2.60
-
V
-
245
-
ns
POWER-ON RESET AND ENABLE
VCC Rising Threshold
VCC Falling Threshold
PWM INPUT (See “TIMING DIAGRAM” on page 8)
Input Current
IPWM
Shutdown Hold-off Time
tTSSHD
UGATE Rise Time
tRU
VPVCC = 12V, 3nF Load, 10% to 90%
-
26
-
ns
LGATE Rise Time
tRL
VPVCC = 12V, 3nF Load, 10% to 90%
-
18
-
ns
UGATE Fall Time
tFU
VPVCC = 12V, 3nF Load, 90% to 10%
-
18
-
ns
LGATE Fall Time
tFL
VPVCC = 12V, 3nF Load, 90% to 10%
-
12
-
ns
VPVCC = 12V, 3nF Load, Adaptive
-
10
-
ns
UGATE Turn-On Propagation Delay (Note 4)
5
tPDHU
FN9155.5
May 5, 2008
ISL6614
Electrical Specifications
Recommended Operating Conditions, Unless Otherwise Noted. (Continued)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
LGATE Turn-On Propagation Delay (Note 4)
tPDHL
VPVCC = 12V, 3nF Load, Adaptive
-
10
-
ns
UGATE Turn-Off Propagation Delay (Note 4)
tPDLU
VPVCC = 12V, 3nF Load
-
10
-
ns
LGATE Turn-Off Propagation Delay (Note 4)
tPDLL
VPVCC = 12V, 3nF Load
-
10
-
ns
LG/UG Three-State Propagation Delay (Note 4)
tPDTS
VPVCC = 12V, 3nF Load
-
10
-
ns
Upper Drive Source Current
IU_SOURCE
VPVCC = 12V, 3nF Load
-
1.25
-
A
Upper Drive Source Impedance
RU_SOURCE 150mA Source Current
1.4
2.0
3.0
Ω
2
-
A
-
1.3
2.2
Ω
0.9
1.65
3.0
Ω
-
2
-
A
0.85
1.3
2.2
Ω
-
3
-
A
0.60
0.94
1.35
Ω
Thermal Shutdown Setpoint
-
150
-
°C
Thermal Recovery Setpoint
-
108
-
°C
OUTPUT (Note 4)
Upper Drive Sink Current
IU_SINK
VPVCC = 12V, 3nF Load
Upper Drive Transition Sink Impedance
RU_SINK_TR
Upper Drive DC Sink Impedance
RU_SINK_DC 150mA Source Current
Lower Drive Source Current
IL_SOURCE
Lower Drive Source Impedance
RL_SOURCE 150mA Source Current
VPVCC = 12V, 3nF Load
Lower Drive Sink Current
IL_SINK
VPVCC = 12V, 3nF Load
Lower Drive Sink Impedance
RL_SINK
150mA Sink Current
OVER-TEMPERATURE SHUTDOWN
NOTES:
4. Limits should be considered typical and are not production tested.
6
FN9155.5
May 5, 2008
ISL6614
Functional Pin Description
PACKAGE PIN
NUMBER
SOIC
DFN
PIN
SYMBOL
1
15
PWM1
The PWM signal is the control input for the Channel 1 driver. The PWM signal can enter three distinct states during
operation, see “Three-State PWM Input” on page 8 for further details. Connect this pin to the PWM output of the
controller.
2
16
PWM2
The PWM signal is the control input for the Channel 2 driver. The PWM signal can enter three distinct states during
operation, see see “Three-State PWM Input” on page 8 for further details. Connect this pin to the PWM output of the
controller.
3
1
GND
4
2
LGATE1
5
3
PVCC
This pin supplies power to both the lower and higher gate drives in ISL6614. Its operating range is +5V to 12V.
Place a high quality low ESR ceramic capacitor from this pin to GND.
6
4
PGND
It is the power ground return of both low gate drivers.
-
5, 8
N/C
7
6
LGATE2
Lower gate drive output of Channel 2. Connect to gate of the low-side power N-Channel MOSFET.
8
7
PHASE2
Connect this pin to the SOURCE of the upper MOSFET and the DRAIN of the lower MOSFET in Channel 2. This
pin provides a return path for the upper gate drive.
9
9
UGATE2
Upper gate drive output of Channel 2. Connect to gate of high-side power N-Channel MOSFET.
10
10
BOOT2
Floating bootstrap supply pin for the upper gate drive of Channel 2. Connect the bootstrap capacitor between this
pin and the PHASE2 pin. The bootstrap capacitor provides the charge to turn on the upper MOSFET. See the
“Internal Bootstrap Device” on page 9 for guidance in choosing the capacitor value.
11
11
BOOT1
Floating bootstrap supply pin for the upper gate drive of Channel 1. Connect the bootstrap capacitor between this
pin and the PHASE1 pin. The bootstrap capacitor provides the charge to turn on the upper MOSFET. See “Internal
Bootstrap Device” on page 9 for guidance in choosing the capacitor value.
12
12
UGATE1
Upper gate drive output of Channel 1. Connect to gate of high-side power N-Channel MOSFET.
13
13
PHASE1
Connect this pin to the SOURCE of the upper MOSFET and the DRAIN of the lower MOSFET in Channel 1. This
pin provides a return path for the upper gate drive.
14
14
VCC
Connect this pin to a +12V bias supply. It supplies power to internal analog circuits. Place a high quality low ESR
ceramic capacitor from this pin to GND.
-
17
PAD
Connect this pad to the power ground plane (GND) via thermally enhanced connection.
FUNCTION
Bias and reference ground. All signals are referenced to this node.
Lower gate drive output of Channel 1. Connect to gate of the low-side power N-Channel MOSFET.
No Connection.
7
FN9155.5
May 5, 2008
ISL6614
Description
1.5V<PWM<3.2V
1.0V<PWM<2.6V
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 ISL6614 MOSFET
driver controls both high-side and low-side N-Channel FETs
of two half-bridge power trains from two externally provided
PWM signals.
Prior to VCC exceeding its POR level, the Pre-POR
overvoltage protection function is activated; 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” table on page 5), 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 8). After a short propagation delay [tPDLL],
the lower gate begins to fall. Typical fall times [tFL] are provided
in the “Electrical Specifications” table on page 5. Adaptive
shoot-through circuitry monitors the PHASE 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 for details). The
lower gate then rises [tRL], turning on the lower MOSFET.
Advanced Adaptive Zero Shoot-Through Deadtime
Control (Patent Pending)
These drivers incorporate a unique adaptive deadtime control
technique to minimize deadtime, resulting in high efficiency
8
from the reduced freewheeling time of the lower MOSFETs’
body-diode conduction, and to prevent the upper and lower
MOSFETs from conducting simultaneously. This is
accomplished by ensuring either 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 PHASE voltage is
monitored until it reaches a -0.2V/+0.8V trip point for a
forward/reverse current, at which time the UGATE is released
to rise. An auto-zero comparator is used to correct the
rDS(ON) drop in the phase voltage preventing from false
detection of the -0.2V phase level during rDS(ON) conduction
period. In the case of zero current, the UGATE is released
after 35ns delay of the LGATE dropping below 0.5V. During
the phase detection, the disturbance of LGATE’s falling
transition on the PHASE node is blanked out to prevent falsely
tripping. Once the PHASE is high, the advanced adaptive
shoot-through circuitry monitors the PHASE and UGATE
voltages during a PWM falling edge and the subsequent
UGATE turn-off. If either the UGATE falls to less than 1.75V
above the PHASE or the PHASE falls to less than +0.8V, the
LGATE is released to turn on.
Three-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 the “Electrical Specifications” table on
page 5 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
FN9155.5
May 5, 2008
ISL6614
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 three-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.
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.
1.6
1.4
1.2
During initial startup, the VCC voltage rise is monitored.
Once the rising VCC voltage exceeds 9.8V (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 7.6V (typically), operation of the driver is
disabled.
1.0
0.8
0.6
QGATE = 100nC
0.4
50nC
Pre-POR Overvoltage Protection
0.2
Prior to VCC exceeding its POR level, the upper gate is held
low and the lower gate is controlled by the overvoltage
protection circuits during initial startup. 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 initial startup. For
complete protection, the low side MOSFET should have a
gate threshold well below the maximum voltage rating of the
load/microprocessor.
When VCC drops below its POR level, both gates pull low
and the Pre-POR overvoltage protection circuits are not
activated until VCC resets.
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 UVCC + 5V and its capacitance value can be
chosen from Equation 1:
Q GATE
C BOOT_CAP ≥ -------------------------------------ΔV BOOT_CAP
CBOOT_CAP (µF)
Power-On Reset (POR) Function
(EQ. 1)
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 ISL6614 provides the user flexibility in choosing the
gate drive voltage for efficiency optimization. The ISL6614
ties the upper and lower drive rails together. Simply applying
a voltage from 5V up to 12V on PVCC sets both gate drive
rail voltages simultaneously. Connecting a SOT-23 package
type of dual Schottky diodes from the VCC to BOOT1 and
BOOT2 can bypass the internal bootstrap devices of both
upper gates so that the part can operate as a dual ISL6612
driver, which has a fixed VCC (12V typically) on the upper
gate and a programmable lower gate drive voltage.
Over-Temperature Protection (OTP)
When the junction temperature of the IC exceeds +150°C
(typically), both upper and lower gates turn off. The driver
stays off and does not return to normal operation until its
junction temperature comes down below +108°C (typically).
For high frequency applications, applying a lower voltage to
PVCC helps reduce the power dissipation and lower the
junction temperature of the IC. This method reduces the risk
of tripping OTP.
Power Dissipation
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 per channel. 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
9
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
FN9155.5
May 5, 2008
ISL6614
the SO14 package is approximately 1W at room
temperature, while the power dissipation capacity in the
QFN packages, with an exposed heat escape pad, is around
2W. See “Layout Considerations” on page 10 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 using Equations 2 and 3,
respectively:
P Qg_TOT = 2 • P Qg_Q1 + 2 • P Qg_Q2 + I Q • VCC
BOOT
PVCC
D
CGD
RHI1
RLO1
G
RG1
CDS
RGI1
CGS
Q1
S
PHASE
FIGURE 3. TYPICAL UPPER-GATE DRIVE TURN-ON PATH
(EQ. 2)
Q G1 • PVCC 2
P Qg_Q1 = --------------------------------------- • F SW • N Q1
V GS1
PVCC
D
• PVCC 2
Q G2
P Qg_Q2 = --------------------------------------- • F SW • N Q2
V GS2
CGD
RHI2
RLO2
G
RG2
CDS
RGI2
CGS
⎛ Q G1 • N Q1 Q G2 • N Q2⎞
I DR = ⎜ ------------------------------ + ------------------------------⎟ • F SW • 2 + I Q
V GS2 ⎠
⎝ V GS1
Q2
S
(EQ. 3)
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 number of upper and lower MOSFETs,
respectively; PVCC is the drive voltages for both upper and
lower FETs, respectively. The IQ*VCC product is the
quiescent power of the driver without capacitive load and is
typically 200mW at 300kHz.
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:
P DR = 2 • P DR_UP + 2 • P DR_LOW + I Q • VCC
(EQ. 4)
R LO1
R HI1
⎛
⎞ P Qg_Q1
P DR_UP = ⎜ -------------------------------------- + ----------------------------------------⎟ • --------------------R
+
R
R
+
R
2
⎝ HI1
EXT1
LO1
EXT1⎠
FIGURE 4. TYPICAL LOWER-GATE DRIVE TURN-ON PATH
Layout Considerations
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 copper 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.
Place each channel power component as close to each
other as possible to reduce PCB copper losses and PCB
parasitics: shortest distance between DRAINs of upper FETs
and SOURCEs of lower FETs; shortest distance between
DRAINs of lower FETs and the power ground. Thus, smaller
amplitudes of positive and negative ringing are on the
switching edges of the PHASE node. However, some space
in between the power components is required for good
airflow. The traces from the drivers to the FETs should be
kept short and wide to reduce the inductance of the traces
and to promote clean drive signals.
R LO2
R HI2
⎛
⎞ P Qg_Q2
P DR_LOW = ⎜ -------------------------------------- + ----------------------------------------⎟ • --------------------2
⎝ R HI2 + R EXT2 R LO2 + R EXT2⎠
R GI1
R EXT1 = R G1 + ------------N
Q1
R GI2
R EXT2 = R G2 + ------------N
Q2
10
FN9155.5
May 5, 2008
ISL6614
Quad Flat No-Lead Plastic Package (QFN)
Micro Lead Frame Plastic Package (MLFP)
L16.4x4
16 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
(COMPLIANT TO JEDEC MO-220-VGGC ISSUE C)
MILLIMETERS
SYMBOL
MIN
NOMINAL
MAX
NOTES
A
0.80
0.90
1.00
-
A1
-
-
0.05
-
A2
-
-
1.00
A3
b
0.23
D
0.28
9
0.35
5, 8
4.00 BSC
D1
D2
9
0.20 REF
-
3.75 BSC
1.95
2.10
9
2.25
7, 8
E
4.00 BSC
-
E1
3.75 BSC
9
E2
1.95
e
2.10
2.25
7, 8
0.65 BSC
-
k
0.25
-
-
-
L
0.50
0.60
0.75
8
L1
-
-
0.15
10
N
16
2
Nd
4
3
Ne
4
3
P
-
-
0.60
9
θ
-
-
12
9
Rev. 5 5/04
NOTES:
1. Dimensioning and tolerancing conform to ASME Y14.5-1994.
2. N is the number of terminals.
3. Nd and Ne refer to the number of terminals on each D and E.
4. All dimensions are in millimeters. Angles are in degrees.
5. Dimension b applies to the metallized terminal and is measured
between 0.15mm and 0.30mm from the terminal tip.
6. The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 identifier may be
either a mold or mark feature.
7. Dimensions D2 and E2 are for the exposed pads which provide
improved electrical and thermal performance.
8. Nominal dimensions are provided to assist with PCB Land Pattern
Design efforts, see Intersil Technical Brief TB389.
9. Features and dimensions A2, A3, D1, E1, P & θ are present when
Anvil singulation method is used and not present for saw
singulation.
10. Depending on the method of lead termination at the edge of the
package, a maximum 0.15mm pull back (L1) maybe present. L
minus L1 to be equal to or greater than 0.3mm.
11
FN9155.5
May 5, 2008
ISL6614
Small Outline Plastic Packages (SOIC)
M14.15 (JEDEC MS-012-AB ISSUE C)
N
INDEX
AREA
H
0.25(0.010) M
14 LEAD NARROW BODY SMALL OUTLINE PLASTIC
PACKAGE
B M
E
INCHES
-B-
1
2
3
L
SEATING PLANE
-A-
h x 45o
A
D
-C-
α
e
A1
B
0.25(0.010) M
C A M
SYMBOL
MIN
MAX
MIN
MAX
NOTES
A
0.0532
0.0688
1.35
1.75
-
A1
0.0040
0.0098
0.10
0.25
-
B
0.013
0.020
0.33
0.51
9
C
0.0075
0.0098
0.19
0.25
-
D
0.3367
0.3444
8.55
8.75
3
E
0.1497
0.1574
3.80
4.00
4
e
C
0.10(0.004)
B S
0.050 BSC
1. Symbols are defined in the “MO Series Symbol List” in Section 2.2 of
Publication Number 95.
1.27 BSC
-
H
0.2284
0.2440
5.80
6.20
-
h
0.0099
0.0196
0.25
0.50
5
L
0.016
0.050
0.40
1.27
6
N
NOTES:
MILLIMETERS
α
14
0o
14
8o
0o
7
8o
Rev. 0 12/93
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Dimension “D” 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.
4. Dimension “E” does not include interlead flash or protrusions. Interlead
flash and protrusions shall not exceed 0.25mm (0.010 inch) per side.
5. The chamfer on the body is optional. If it is not present, a visual index
feature must be located within the crosshatched area.
6. “L” is the length of terminal for soldering to a substrate.
7. “N” is the number of terminal positions.
8. Terminal numbers are shown for reference only.
9. The lead width “B”, 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).
10. Controlling dimension: MILLIMETER. Converted inch dimensions
are not necessarily exact.
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
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 without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
12
FN9155.5
May 5, 2008