Datasheet ISL6615A Datasheet (intersil)

®

ISL6615A

Data Sheet April 30, 2008

High-Frequency 6A Sink Synchronous
MOSFET Drivers with Protection 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.

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.

FN6608.0

Features

• Dual MOSFET Drives for Synchronous Rectified Bridge

• Advanced Adaptive Zero Shoot-Through Protection

- Body Diode Detection

- LGATE Detection

- Auto-zero of r

• 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)

Conduction Offset Effect

DS(ON)

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”

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.

All other trademarks mentioned are the property of their respective owners.

Copyright Intersil Americas Inc. 2008. All Rights Reserved

ISL6615A

Ordering Information

PART NUMBER

(Note) PART MARKING

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 +70 8 Ld SOIC M8.15
ISL6615AIRZ* 15AI -40 to +70 10 Ld 3x3 DFN L10.3x3
*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.

TEMP.

RANGE (°C)

PACK AGE

(Pb-free)

PKG.

DWG. #

Pinouts

ISL6615ACB

(8 LD SOIC)

TOP VIEW

ISL6615ACR

(10 LD 3x3 DFN)

TOP VIEW

UGATE

BOOT

PWM

GND

Block Diagram

1
2
3
4

VCC

PWM

+5V

10k

8k

8

PHASE

7

PVCC

6

VCC

5

LGATE

(UVCC)

PRE-POR OVP

FEATURES

POR/

CONTROL

LOGIC

ISL6615A

SHOOT-

THROUGH

PROTECTION

10

9
8
7
6

PHASE
PVCC

N/C
VCC

LGATE

BOOT

N/C

PWM

GND

1
2
3
4
5

GND

BOOT

UGATE

PHASE

PVCC

LGATE

GND

UVCC = PVCC

UGATE

RECOMMEND TO CONNECT PIN 3 TO GND AND PIN 8 TO PVCC

(LVCC)

SUBSTRATE RESIST ANCE

PAD

2

FOR DFN DEVICES, THE PAD ON THE BOTTOM SIDE OF
THE PACKAGE MUST BE SOLDERED TO THE CIRCUIT’S GROUND.

FN6608.0

April 30, 2008

Typical Application - 2 Channel Converter

3

+7V TO +13.2V

+5V

GND

GND

BOOT

UGATE

PHASE
LGATE

BOOT

UGATE

PHASE
LGATE

PGOOD

VID

(OPTIONAL)

+5V

FB

VCC

VSEN

PWM

CONTROL

(ISL63xx

OR ISL65xx)

FS/EN

GND

COMP

PWM1
PWM2

ISEN1
ISEN2

PVCC

VCC

PWM

ISL6615A

+7V TO +13.2V

PVCC

VCC

PWM

ISL6615A

V

IN

ISL6615A

+V

V

IN

CORE

THE ISL6615A CAN SUPPORT 5V PWM INPUT

April 30, 2008

FN6608.0

ISL6615A

Absolute Maximum Ratings Thermal Information

Supply Voltage (VCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15V

Supply Voltage (PVCC) . . . . . . . . . . . . . . . . . . . . . . . . . VCC + 0.3V

BOOT Voltage (V
Input Voltage (V

UGATE. . . . . . . . . . . . . . . . . . . V

V

BOOT-GND

PWM

- 3.5V (<100ns Pulse Width, 2µJ) to V

PHASE

LGATE. . . . . . . . . . . . . . . . . . . . . . GND - 0.3V

GND - 5V (<100ns Pulse Width, 2µJ) to V

PHASE. . . . . . . . . . . . . . . . . . . . . . . . . . . . GND - 0.3V

GND - 8V (<400ns, 20µJ) to 30V (<200ns, V

ESD Rating

). . . . . . . . . . . . . . . . . . . . . . . . . . . .36V

) . . . . . . . . . . . . . . . . . . . . . .GND - 0.3V to 7V

PHASE

- 0.3VDC to V

to V

DC

BOOT-GND

BOOT
BOOT
PVCC
PVCC

to 15V

DC

+ 0.3V
+ 0.3V
+ 0.3V
+ 0.3V

DC

< 36V))

Human Body Model . . . . . . . . . . . . . . . . . . . .Class I JEDEC STD

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:

is measured with the component mounted on a high effective thermal conductivity test board in free air.

1. θ

JA

is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See

2. θ

JA

Tech Brief TB379.

3. For θ

, the “case temp” location is the center of the exposed metal pad on the package underside.

JC

Thermal Resistance θ

(°C/W) θJC (°C/W)

JA

SOIC Package (Note 1) . . . . . . . . . . . . 100 N/A

DFN Package (Notes 2, 3). . . . . . . . . . 48 7

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

Maximum Operating Junction Temperature. . . . . . . . . . . . . . +125°C

VCC Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8V to 13.2V

PVCC Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . 5V to 12V ±10%

Electrical Specifications Recommended Operating Conditions; 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.

PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNITS

VCC SUPPLY CURRENT

Bias Supply Current I
Gate Drive Bias Current I

VCC

PVCC

POWER-ON RESET AND ENABLE

VCC Rising Threshold 6.1 6.4 6.7 V
VCC Falling Threshold 4.7 5.0 5.3 V

PWM INPUT (See “TIMING DIAGRAM” on page 6)

Input Current I

PWM

PWM Rising Threshold (Note 4) VCC = 12V - 3.00 - V
PWM Falling Threshold (Note 4) VCC = 12V - 2.00 - V
Typical Tri-State Shutdown Window VCC = 12V 1.80 - 2.40 V
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
Shutdown Holdoff Time t
UGATE Rise Time (Note 4) t
LGATE Rise Time (Note 4) t
UGATE Fall Time (Note 4) t
LGATE Fall Time (Note 4) t

TSSHD

RU

RL
FU
FL

f

= 300kHz, V

PWM

f

= 300kHz, V

PWM

V

= 5V - 510 - µA

PWM

V

= 0V - -475 - µA

PWM

= 12V - 4.5 - mA

VCC

= 12V - 8 - mA

PVCC

-65-ns

V

= 12V, 3nF Load, 10% to 90% - 13 - ns

PVCC

V

= 12V, 3nF Load, 10% to 90% - 10 - ns

PVCC

V

= 12V, 3nF Load, 90% to 10% - 10 - ns

PVCC

V

= 12V, 3nF Load, 90% to 10% - 10 - ns

PVCC

4

FN6608.0

April 30, 2008

ISL6615A

Electrical Specifications Recommended Operating Conditions; 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. (Continued)

PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNITS

UGATE Turn-On Propagation Delay (Note 4) t
LGATE Turn-On Propagation Delay (Note 4) t
UGATE Turn-Off Propagation Delay (Note 4) t
LGATE Turn-Off Propagation Delay (Note 4) t
LG/UG Tri-State Propagation Delay (Note 4) t

PDHU
PDHL
PDLU

PDLL

PDTS

OUTPUT (Note 4)

Upper Drive Source Current I
Upper Drive Source Impedance R
Upper Drive Sink Current I
Upper Drive Sink Impedance R
Lower Drive Source Current I
Lower Drive Source Impedance R
Lower Drive Sink Current I
Lower Drive Sink Impedance R

U_SOURCEVPVCC

U_SOURCE

U_SINK

U_SINK

L_SOURCEVPVCC

L_SOURCE

L_SINK

L_SINK

NOTE:

4. Limits established by characterization and are not production tested.

V

= 12V, 3nF Load, Adaptive - 10 - ns

PVCC

V

= 12V, 3nF Load, Adaptive - 10 - ns

PVCC

V

= 12V, 3nF Load - 10 - ns

PVCC

V

= 12V, 3nF Load - 10 - ns

PVCC

V

= 12V, 3nF Load - 10 - ns

PVCC

= 12V, 3nF Load - 2.5 - A
150mA Source Current - 1 - Ω
V

= 12V, 3nF Load - 4 - A

PVCC

150mA Sink Current - 0.8 - Ω

= 12V, 3nF Load - 4 - A
150mA Source Current - 0.7 - Ω
V

= 12V, 3nF Load - 6 - A

PVCC

150mA Sink Current - 0.45 - Ω

Functional Pin Description

PACKAGE PIN #

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

- 3, 8 N/C No Co nnectio n. Recom mend to con nect pin 3 to GND an d pin 8 to PV CC.

3 4 PWM The PWM signal is the control input for the driver. The PWM signal can enter three distinct states during operation, see

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 Lower gate drive output. Connect to gate of the low-side power N-Channel MOSFET.
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

8 10 PHASE Connect this pin to the SOURCE of the upper MOSFET and the DRAIN of the lower MOSFET. This pin provides

9 11 PAD Connect this pad to the power ground plane (GND) via thermally enhanced connection.

PIN

SYMBOL FUNCTIONSOIC DFN

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.

the “TIMING DIAGRAM” on page 6 section under Description for further details. Connect this pin to the PWM output of
the controller.

quality low ESR ceramic capacitor from this pin to GND.

a return path for the upper gate drive.

5

FN6608.0

April 30, 2008

Description

ISL6615A

PWM

t

PDLU

t

FU

t

RL

FIGURE 1. TIMING DIAGRAM

UGATE

LGATE

t

PDLL

t

PDHU

t

RU

t

FL

t

PDHL

Operation

Designed for versatility and speed, the ISL6615A MOSFET
driver controls both high-side and low-side N-Channel FETs
of a half-bridge 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 [t
gate begins to fall. Typical fall times [t

] are provided in the

FL

“Electrical Specifications” on page 4. Adaptive shoot-through
circuitry monitors the LGATE voltage and determines the
upper gate delay time [t

]. This prevents both the lower

PDHU

and upper MOSFETs from conducting simultaneously. Once
this delay period is complete, the upper gate drive begins to
rise [t

] and the upper MOSFET turns on.

RU

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 [t
gate begins to fall [t

] is encountered before the upper

PDLU

]. Again, the adaptive shoot-through

FU

circuitry determines the lower gate delay time, t
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
[t

], turning on the lower MOSFET.

RL

PDLL

PDHL

], the lower

. The

1.18V < PWM < 2.36V

t

TSSHD

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 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 peri od 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 propogation delay. If the
UGATE-PHASE falls to less than 1.75V and after 40ns of
propogation 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

t

PDTS

0.76V < PWM < 1.96V

t

TSSHD

t

PDTS

6

FN6608.0

April 30, 2008

ISL6615A

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.

Power-On Reset (POR) Function

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.

Pre-POR Overvoltage Protection

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

Q

GATE

where Q
at V

GS1

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 FET s are chosen as
the upper MOSFETs. The gate charge, Q

--------------------------------------

≥

ΔV

BOOT_CAP

QG1PVCC•

----------------------------------- -

V

GS1

is the amount of gate charge per upper MOSFET

G1

•=

N

Q1

gate-source voltage and NQ1 is the number of

, from the data

G

(EQ. 1)

sheet is 10nC at 4.5V (V
Q

is calculated to be 53nC for PVCC = 12V. We will

GATE

) gate-source voltage. Then the

GS

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.

1.6

1.6

1.4

1.2

1.0

(µF)

0.8

0.6

BOOT_CAP

C

0.4

0.2
20nC

0.0

FIGURE 2. BOOTSTRAP CAPACITANCE vs BOOT RIPPLE

Q

50nC

VOLTAGE

= 100nC

GATE

0.30.0 0.1 0.2 0.4 0.5 0.6 0.90.7 0.8 1.0
ΔV

BOOT_CAP

(V)

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 1 3. 2V on PVC C
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 i s mai nl y a fu nction of the
switching frequency (F
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 MOSFET s. The tot al gate
drive power losses due to the gate charge of MOSFETs and
the driver’s internal circuitry and their corresponding average

), the output drive impedance, the

SW

7

FN6608.0

April 30, 2008

ISL6615A

driver current can be estimated with Equations 2 and 3,
respectively:

P

Qg_TOTPQg_Q1PQg_Q2IQ

QG1PVCC

•

P

Qg_Q1

P

Qg_Q2

⎛⎞

I

⎜⎟

DR

⎝⎠

---------------------------------------

V

QG2PVCC

•

---------------------------------------

V

QG1PVCC NQ1••

-----------------------------------------------------

V

GS1

where the gate charge (Q

2

GS1

2

GS2

+

G1

particular gate to source voltage (V

VCC•++=

• NQ1•=

F

SW

• NQ2•=

F

SW

Q

PVCC NQ2••

G2

-----------------------------------------------------

V

GS2

and QG2) is defined at a

and V

GS1

GS2

(EQ. 2)

+•=

F

SWIQ

(EQ. 3)

) in the
corresponding MOSFET datasheet; IQ is the driver’s total
quiescent current with no load at both drive outputs; N
and N

are the number of upper and lower MOSFETs,

Q2

Q1

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 (R
(R

and R

GI1

and RG2) and the internal gate resistors

G1

) of MOSFETs. Figures 3 and 4 show the

GI2

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

DRPDR_UPPDR_LOWIQ

R

⎛⎞

HI1

P

DR_UP

P

DR_LOW

R

EXT1RG1

--------------------------------------

⎜⎟

R

+

⎝⎠

HI1REXT1

R

⎛⎞

HI2

--------------------------------------

⎜⎟

R

+

⎝⎠

HI2REXT2

R

GI1

-------------

+=

N

Q1

VCC•++=

R

LO1

----------------------------------------

+

R

+

LO1REXT1

R

LO2

----------------------------------------

+

R

+

LO2REXT2

R

EXT2RG2

P

Qg_Q1

---------------------

•=

P

---------------------

•=

R

-------------

+=

N

(EQ. 4)

2

Qg_Q2

2

GI2

Q2

Application Information

Layout Considerations

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
lower the stress applied to the output drives. The following
advice is meant to lead to an optimized layout and
performance:

• Keep decoupling loops (VCC-GND, PVCC-GND and

• Minimize trace inductance, especially on low-impedance

PVCC

BOOT

R

PHASE

R

HI1

LO1

D

C

GD

G

R

GI1

R

G1

C

GS

S

Q1

C

DS

FIGURE 3. TYPICAL UPPER-GATE DRIVE TURN-ON PATH

PVCC

D

C

GD

R

HI2

R

LO2

G2

G

R

GI2R

C

GS

S

Q2

C

DS

FIGURE 4. TYPICAL LOWER-GATE DRIVE TURN-ON PATH

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.

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, connect it to the adjacent net (LGA TE2/PHASE2) can
reduce trace inductance.

8

FN6608.0

April 30, 2008

ISL6615A

• Shorten all gate drive loops (UGATE-PHASE and

LGATE-GND) and route them closely spaced.

• 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.

• 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.

• 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

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 C
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 (R

) across the gate and source of the

UGPH

upper MOSFET to suppress the Miller coupling effect. The
value of the resistor depends mainly on the input voltage’s
rate of rise, the C

GD/CGS

ratio, as well as the gate-source

threshold of the upper MOSFET. A higher dV/dt, a lower

of the MOSFET, the

GD

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.

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.

V–

--------------------------------- -

dV

-------

⋅

dt

G

UGPH

DS

RC⋅

iss

C

issCGDCGS

C

GD

R

GI

C

GS

(EQ. 5)

+=

VIN

D

C

DS

Q

UPPER

S

⎛⎞

dV

V

GS_MILLER

RR

UGPHRGI

PVCC

ISL6615A

FIGURE 5. GATE-TO-SOURCE RESISTOR TO REDUCE

-------

⋅⋅=

dt

+=

DU
DL

UPPER MOSFET MILLER COUPLING

⎜⎟
⎜⎟

1e

RC

–

rss

⎜⎟
⎜⎟
⎝⎠

C

=

rssCGD

BOOT

C

BOOT

UGATE

R

PHASE

9

FN6608.0

April 30, 2008

Dual Flat No-Lead Plastic Package (DFN)

ISL6615A

INDEX

SEATING

(DATUM B)

6

INDEX

AREA

(DATUM A)

NX (b)

5

SECTION "C-C"

6

AREA

C

PLANE

NX L

8

A

D

TOP VIEW

SIDE VIEW

7

D2

12

BOTTOM VIEW

D2/2

N-1N
e

(Nd-1)Xe

REF.

(A1)

2X

0.15

C

A

L10.3x3

10 LEAD DUAL FLAT NO-LEAD PLASTIC PACKAGE

MILLIMETERS

0.152XB

C

SYMBOL

NOTESMIN NOMINAL MAX

A 0.80 0.90 1.00 -

A1 - - 0.05 -

E

A3 0.20 REF -

b 0.18 0.23 0.28 5,8

D 3.00 BSC -

B

D2 1.95 2.00 2.05 7,8

E 3.00 BSC -

E2 1.55 1.60 1.65 7,8

0.10 C

A

0.08

C

e 0.50 BSC -

k0.25 - - ­L0.300.35 0.40 8

A3

N102

Nd 5 3

8

Rev. 3 6/04

NOTES:

1. Dimensioning and tolerancing conform to ASME Y14.5-1994.

2. N is the number of terminals.

3. Nd refers to the number of terminals on D.

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

E2/2

NX

E2

k

located within the zone indicated. The pin #1 identifier may be
either a mold or mark feature.

NX b
5

0.10 MC

0.415

C

0.200

NX b

AB

NX L

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.

C

L

L

e

CC

FOR ODD TERMINAL/SIDE

TERMINAL TIP

10

FN6608.0

April 30, 2008

Small Outline Plastic Packages (SOIC)

ISL6615A

N

INDEX
AREA

123

-A-

E

-B-

SEATING PLANE

D

A

-C-

0.25(0.010) BM M

H

L

h x 45°

α

e

B

0.25(0.010) C AM BS

M

NOTES:

1. Symbols are defined in the “MO Series Symbol List” in Section 2.2 of
Publication Number 95.

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.

A1

C

0.10(0.004)

M8.15 (JEDEC MS-012-AA ISSUE C)

8 LEAD NARROW BODY SMALL OUTLINE PLASTIC PACKAGE

INCHES MILLIMETERS

SYMBOL

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 0.1890 0.1968 4.80 5.00 3

E 0.1497 0.1574 3.80 4.00 4

e 0.050 BSC 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

N8 87

α

0° 8° 0° 8° -

NOTESMIN MAX MIN MAX

Rev. 1 6/05

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 implicat ion or oth erwise u nde r any p a tent or p at ent r ights of Intersil or its subsidiaries.

For information regarding Intersil Corporation and its products, see www.intersil.com

11

FN6608.0

April 30, 2008