Fairchild FDMF6705B service manual

March 2012

FDMF6705B - Extra-Small, High-Performance, HighFrequency DrMOS Module

FDMF6705B - Extra-Small, High-Performance, High-Frequency DrMOS Module

Benefits

 Ultra-Compact 6x6mm PQFN, 72% Space-Saving

Compared to Conventional Discrete Solutions

 Fully Optimized System Efficiency  Clean Switching Waveforms with Minimal Ringing  High-Current Handling

Features

 Over 93% Peak-Efficiency  High-Current Handling of 40A at 12V  High-Current Handling of 38A at 19V

IN

 High-Performance PQFN Copper-Clip Package  3-State 3.3V PWM Input Driver  Skip-Mode SMOD# (Low-Side Gate Turn-Off) Input  Thermal Warning Flag for Over-Temperature

Condition

 Driver Output Disable Function (DISB# Pin)  Internal Pull-Up and Pull-Down for SMOD# and

DISB# Inputs, Respectively

 Fairchild PowerTrench

Clean Voltage Waveforms and Reduced Ringing

®

Technology MOSFETs for

 Fairchild SyncFET™ (Integrated Schottky Diode)

Technology in the Low-Side MOSFET

 Integrated Bootstrap Schottky Diode  Adaptive Gate Drive Timing for Shoot-Through

Protection

 Under-Voltage Lockout (UVLO)  Optimized for Switching Frequencies up to 1MHz  Low-Profile SMD Package  Fairchild Green Packaging and RoHS Compliance  Based on the Intel

®

4.0 DrMOS Standard

Description

The XS™ DrMOS family is Fairchild’s next-generation, fully optimized, ultra-compact, integrated MOSFET plus driver power stage solution for high-current, highfrequency, synchronous buck DC-DC applications. The FDMF6705B integrates a driver IC, two power MOSFETs, and a bootstrap Schottky diode into a thermally enhanced, ultra-compact 6x6mm PQFN package.

With an integrated approach, the complete switching power stage is optimized with regards to driver and MOSFET dynamic performance, system inductance, and power MOSFET R Fairchild's high-performance PowerTrench technology, which dramatically reduces switch ringing, eliminating the need for a snubber circuit in most buck converter applications.

A new driver IC with reduced dead times and propagation delays further enhances the performance of this part. A thermal warning function warns of a potential over-temperature situation. The FDMF6705B also incorporates features, such as Skip Mode (SMOD), for improved light-load efficiency, along with a three-state

3.3V PWM input for compatibility with a wide range of PWM controllers.

XS™ DrMOS uses

DS(ON).

®

MOSFET

Applications

High-Performance Gaming Motherboards

  Notebook Computers, V-Core and Non-V-Core  Compact Blade Servers, V-Core and Non-V-Core

DC-DC Converters

 Desktop Computers, V-Core and Non-V-Core

DC-DC Converters

 Workstations  High-Current DC-DC Point-of-Load (POL)

Converters

 Small Form-Factor Voltage Regulator Modules

Ordering Information

Part Number Current Rating Package Top Mark

FDMF6705B 40A 40-Lead, Clipbond PQFN DrMOS, 6.0x6.0mm Package FDMF6705B

Typical Application Circuit

g

FDMF6705B - Extra-Small, High-Performance, High-Frequency DrMOS Module

V5V

C

VDRV

DISB#

PWM Input

OFF

ON

Open-Drain Output

DrMOS Block Diagram

VCIN

DISB#

PWM

SMOD#

THWN#

VDRV

FDMF6705B

CGND

VIN

R

BOOT

PHASE

VSWH

PGND

Figure 1. Typical Application Circuit

VDRV

BOOT

VIN

C

BOOT

3V ~ 24V

L

OUT

V

OUT

C

OUT

C

VIN

BOOT

VIN

VCIN

DISB#

PWM

THWN#

R

UP_PWM

R

DN_PWM

CGND

10µA

UVLO

V

CIN

Temp. Sense

Input

3-

State

Logic

Q1

D

Boot

GH

Lo

ic

GL

Logic

V

CIN

10µA

SMOD#

Level Shift

Dead Time

Control

GH

30kΩ

V

DRV

GL

30kΩ

HS Power MOSFET

PHASE

VSWH

Q2 LS Power MOSFET

PGND

Figure 2. DrMOS Block Diagram

Pin Configuration

FDMF6705B - Extra-Small, High-Performance, High-Frequency DrMOS Module

Figure 3. Bottom View Figure 4. Top View

Pin Definitions

Pin # Name Description

When SMOD#=HIGH, the low-side driver is the inverse of PWM input. When SMOD#=LOW,

1 SMOD#

2 VCIN IC bias supply. Minimum 1µF ceramic capacitor is recommended from this pin to CGND.

3 VDRV

4 BOOT

5, 37, 41 CGND IC ground. Ground return for driver IC.

6 GH For manufacturing test only. This pin must float; must not be connected to any pin.

7 PHASE Switch node pin for bootstrap capacitor routing. Electrically shorted to VSWH pin.

8 NC

9 - 14, 42 VIN Power input. Output stage supply voltage.

15, 29 -

35, 43

16 – 28 PGND Power ground. Output stage ground. Source pin of low-side MOSFET.

36 GL For manufacturing test only. This pin must float; must not be connected to any pin.

38 THWN#

39 DISB#

40 PWM PWM signal input. This pin accepts a three-state logic-level PWM signal from the controller.

VSWH

the low-side driver is disabled. This pin has a 10µA internal pull-up current source. Do not add a noise filter capacitor.

Power for gate driver. Minimum 1µF ceramic capacitor is recommended, connected as close as possible from this pin to CGND.

Bootstrap supply input. Provides voltage supply to high-side MOSFET driver. Connect a bootstrap capacitor from this pin to PHASE.

No connect. The pin is not electrically connected internally, but can be connected to VIN for convenience.

Switch node input. Provides return for high-side bootstrapped driver and acts as a sense point for the adaptive shoot-through protection.

Thermal warning flag, open collector output. When temperature exceeds the trip limit, the output is pulled LOW. THWN# does not disable the module.

Output disable. When LOW, this pin disables power MOSFET switching (GH and GL are held LOW). This pin has a 10µA internal pull-down current source. Do not add a noise filter capacitor.

FDMF6705B - Extra-Small, High-Performance, High-Frequency DrMOS Module

Absolute Maximum Ratings

Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only.

Symbol Parameter Min. Max. Unit

V

Supply Voltage Referenced to CGND -0.3 6.0 V

CIN

V

Drive Voltage Referenced to CGND -0.3 6.0 V

DRV

V

Output Disable Referenced to CGND -0.3 6.0 V

DISB#

V

PWM Signal Input Referenced to CGND -0.3 6.0 V

PWM

V

Skip Mode Input Referenced to CGND -0.3 6.0 V

SMOD#

VGL Low Gate Manufacturing Test Pin Referenced to CGND -0.3 6.0 V

V

Thermal Warning Flag Referenced to CGND -0.3 6.0 V

THWN#

VIN Power Input Referenced to PGND, CGND -0.3 30.0 V

V

Bootstrap Supply

BOOT

VGH High Gate Manufacturing Test Pin

V

PHASE Referenced to CGND -0.3 30.0 V

PHS

V

Switch Node Input

SWH

V

Bootstrap Supply

BOOT

I

THWN# Sink Current -0.1 7.0 mA

THWN#

I

O(AV)

θ

JPCB

Output Current

Junction-to-PCB Thermal Resistance 3.5 °C/W

(1)

TA Ambient Temperature Range -40 +125 °C

TJ Maximum Junction Temperature +150 °C

T

Storage Temperature Range -55 +150 °C

STG

ESD Electrostatic Discharge Protection

Note:

1. I

is rated using Fairchild’s DrMOS evaluation board, TA = 25°C, natural convection cooling. This rating is limited

O(AV)

by the peak DrMOS temperature, T

= 150°C, and varies depending on operating conditions and PCB layout. This

J

rating can be changed with different application settings.

Referenced to VSWH, PHASE -0.3 6.0 V

Referenced to CGND -0.3 30.0 V

Referenced to VSWH, PHASE -0.3 6.0 V

Referenced to CGND -0.3 30.0 V

Referenced to PGND, CGND (DC Only) -0.3 30.0 V

Referenced to PGND, <20ns -8.0 33.0 V

Referenced to VDRV 22.0 V

Referenced to VDRV, <20ns 25.0 V

fSW=300kHz, VIN=19V, VO=1.0V 38

fSW=1MHz, VIN=19V, VO=1.0V 35

Human Body Model, JESD22-A114 2000

Charged Device Model, JESD22-C101 1000

A

V

Recommended Operating Conditions

The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings.

Symbol Parameter Min. Typ. Max. Unit

V

Control Circuit Supply Voltage 4.5 5.0 5.5 V

CIN

V

Gate Drive Circuit Supply Voltage 4.5 5.0 5.5 V

DRV

VIN Output Stage Supply Voltage 3.0 12.0 24.0

Note:

2. Operating at high V

can create excessive AC overshoots on the VSWH-to-GND and BOOT-to-GND nodes

IN

during MOSFET switching transients. For reliable DrMOS operation, VSWH-to-GND and BOOT-to-GND must

remain at or below the Absolute Maximum Ratings shown in the table above. Refer to the “Application Information” and “PCB Layout Guidelines” sections of this datasheet for additional information.

(2)

V

Electrical Characteristics

Typical values are VIN = 12V, V

Symbol Parameter Condition Min. Typ. Max. Unit

Basic Operation

IQ Quiescent Current IQ=I

UVLO UVLO Threshold V

UVLO

PWM Input (V

R

V

t

D_HOLD-OFF

V

HiZ_PWM

PWM Input (V

R

V

t

D_HOLD-OFF

V

HiZ_PWM

DISB# Input

V

t

PD_DISBL

t

PD_DISBH

SMOD# Input

V

IH_SMOD

V

t

PD_SLGLL

t

PD_SHGLH

UVLO Hysteresis 0.4 V

_Hyst

= V

CIN

Pull-Up Impedance 26 kΩ

UP_PWM

Pull-Down Impedance 12 kΩ

DN_PWM

PWM High Level Voltage

IH_PWM

3-State Upper Threshold

TRI_HI

3-State Lower Threshold

TRI_LO

PWM Low Level Voltage

IL_PWM

= 5V ±10%)

DRV

3-State Shut-off Time 160 200 ns

3-State Open Voltage 1.40 1.60 1.90 V

= V

CIN

Pull-Up Impedance 26 kΩ

UP_PWM

Pull-Down Impedance 12 kΩ

DN_PWM

PWM High Level Voltage

IH_PWM

3-State Upper Threshold

TRI_HI

3-State Lower Threshold

TRI_LO

PWM Low Level Voltage

IL_PWM

= 5V ±5%)

DRV

3-State Shut-off Time 160 200 ns

3-State Open Voltage 1.45 1.60 1.80 V

High-Level Input Voltage 2 V

IH_DISB

Low-Level Input Voltage 0.8 V

IL_DISB

I

Pull-Down Current 10 µA

PLD

Propagation Delay

High-Level Input Voltage 2 V

Low-Level Input Voltage 0.8 V

IL_SMOD

I

Pull-Up Current 10 µA

PLU

Propagation Delay

= 5V, V

CIN

= 5V, and T

DRV

VCIN+IVDRV

Rising 2.9 3.1 3.3 V

CIN

= +25°C unless otherwise noted.

A

, PWM=LOW or HIGH or Float 2 mA

1.88 2.25 2.61

1.84 2.20 2.56

0.70 0.95 1.19

0.62 0.85 1.13

2.00 2.25 2.50

1.94 2.20 2.46

0.75 0.95 1.15

0.66 0.85 1.09

PWM=GND, Delay Between DISB# from HIGH to LOW to GL from HIGH to LOW

PWM=GND, Delay Between DISB# from LOW to HIGH to GL from LOW to HIGH

PWM=GND, Delay Between SMOD# from HIGH to LOW to GL from HIGH to LOW

PWM=GND, Delay Between SMOD# from LOW to HIGH to GL from LOW to HIGH

25 ns

10 ns

Continued on the following page…

V

FDMF6705B - Extra-Small, High-Performance, High-Frequency DrMOS Module

Electrical Characteristics

Typical values are VIN = 12V, V

Symbol Parameter Condition Min. Typ. Max. Unit

Thermal Warning Flag

T

Activation Temperature 150 °C

ACT

T

Reset Temperature 135 °C

RST

R

Pull-Down Resistance I

THWN

250ns Timeout Circuit

t

D_TIMEOUT

High-Side Driver

R

SOURCE_GH

R

t

D_DEADON

t

PD_PLGHL

t

PD_PHGHH

t

PD_TSGHH

Low-Side Driver

R

SOURCE_GL

R

t

D_DEADOFF

t

PD_PHGLL

t

PD_TSGLH

Boot Diode

Timeout Delay

Output Impedance, Sourcing Source Current=100mA 1 Ω

Output Impedance, Sinking Sink Current=100mA 0.8 Ω

SINK_GH

t

Rise Time GH=10% to 90%, C

R_GH

t

Fall Time GH=90% to 10%, C

F_GH

LS to HS Deadband Time

PWM LOW Propagation Delay

PWM HIGH Propagation Delay (SMOD Held LOW)

Exiting 3-State Propagation Delay

Output Impedance, Sourcing Source Current=100mA 1 Ω

Output Impedance, Sinking Sink Current=100mA 0.5 Ω

SINK_GL

t

Rise Time GL=10% to 90%, C

R_GL

t

Fall Time GL=90% to 10%, C

F_GL

HS to LS Deadband Time

PWM-HIGH Propagation Delay

Exiting 3-State Propagation Delay

VF Forward-Voltage Drop IF=10mA 0.35 V

VR Breakdown Voltage IR=1mA 22 V

= 5V, V

CIN

= 5V, and T

DRV

=5mA 30 Ω

PLD

SW=0V, Delay Between GH from HIGH to LOW and GL from LOW to HIGH

GL going LOW to GH going HIGH, 1V GL to 10% GH

PWM going LOW to GH going LOW, V

IL_PWM

PWM going HIGH to GH going HIGH, V

IH_PWM

PWM (from 3-State) going HIGH to GH going HIGH, V

SW going LOW to GL going HIGH,

2.2V SW to 10% GL

PWM going HIGH to GL going LOW, V

IH_PWM

PWM (from 3-State) going LOW to GL going HIGH, V

= +25°C unless otherwise noted.

A

=1.1nF 6 ns

LOAD

=1.1nF 5 ns

LOAD

to 90% GH

to 10% GH (SMOD=LOW)

to 10% GH

IH_PWM

=2.7nF 10 ns

LOAD

=2.7nF 8 ns

LOAD

to 90% GL

to 10% GL

IL_PWM

250 ns

10 ns

16 30 ns

30 ns

12 ns

9 25 ns

20 ns