www.irf.com 1
04/30/08
IRLR7843PbF
IRLU7843PbF
HEXFET® Power MOSFET
Notes through are on page 11
Applications
Benefits
lVery Low RDS(on) at 4.5V VGS
lUltra-Low Gate Impedance
lFully Characterized Avalanche Voltage
and Current
lHigh Frequency Synchronous Buck
Converters for Computer Processor Power
lHigh Frequency Isolated DC-DC
Converters with Synchronous Rectification
for Telecom and Industrial Use
lLead-Free
Absolute Maximum Ratings
Parameter Units
VDS Drain-to-Source Voltage V
VGS Gate-to-Source Voltage
ID @ TC = 25°C Continuous Drain Current, VGS @ 10V
ID @ TC = 10C Continuous Drain Current, VGS @ 10V A
IDM Pulsed Drain Current
c
PD @TC = 25°C Maximum Power Dissipation
g
W
PD @TC = 100°C Maximum Power Dissipation
g
Linear Derating Factor W/°C
TJ Operating Junction and °C
TSTG Storage Temperature Range
Soldering Temperature, for 10 seconds
Thermal Resistance
Parameter Typ. Max. Units
RθJC Junction-to-Case ––– 1.05
RθJA Junction-to-Ambient (PCB Mount)
g
––– 50 °C/W
RθJA Junction-to-Ambient ––– 110
140
Max.
161
f
113
f
620
± 20
30
0.95
71
300 (1.6mm from case)
-55 to + 175
VDSS RDS(on) max Qg
30V 3.3m
:
34nC
D-Pak
IRLR7843PbF
I-Pak
IRLU7843PbF
PD - 95440B
IRLR/U7843PbF
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Static @ TJ = 25°C (unless otherwise specified)
Parameter Min. T
y
p. Max. Units
BVDSS Drain-to-Source Breakdown Voltage 30 ––– ––– V
∆ΒVDSS
/
TJ Breakdown Voltage Temp. Coefficient ––– 19 –– mV/°C
RDS(on) Static Drain-to-Source On-Resistance ––– 2.6 3.3 m
––– 3.2 4.0
VGS(th) Gate Threshold Voltage 1.4 –– 2.3 V
VGS(th)
/
TJGate Threshold Voltage Coefficient ––– -5.4 ––– mVC
IDSS Drain-to-Source Leakage Current ––– ––– 1.0 µA
––– –– 150
IGSS Gate-to-Source Forward Leakage ––– –– 100 nA
Gate-to-Source Reverse Leakage ––– ––– -100
gfs Forward Transconductance 37 –– –– S
QgTotal Gate Charge ––– 34 50
Qgs1 Pre-Vth Gate-to-Source Charge ––– 9.1 –––
Qgs2 Post-Vth Gate-to-Source Charge ––– 2.5 ––– nC
Qgd Gate-to-Drain Charge ––– 12 ––
Qgodr Gate Charge Overdrive ––– 10 ––– See Fig. 16
Qsw Switch Char
g
e (Qgs2 + Qgd)––– 15 ––
Qoss Output Charge ––– 21 –– nC
td(on) Turn-On Delay Time ––– 25 ––
trRise Time ––– 42 –––
td(off) Turn-Off Delay Time –– 34 –– ns
tfFall Time ––– 19 ––
Ciss Input Capacitance ––– 4380 ––
Coss Output Capacitance ––– 940 ––– pF
Crss Reverse Transfer Capacitance ––– 430 ––
Avalanche Characteristics
Parameter Units
EAS
Si
n
gl
e
P
u
l
se
A
va
l
anc
h
e
E
ner
gy
d
mJ
IAR
A
va
l
anc
h
e
C
urrent
c
A
EAR
R
epet
i
t
i
ve
A
va
l
anc
h
e
E
ner
gy
c
mJ
Diode Characteristics
Parameter Min. T
y
p. Max. Units
ISContinuous Source Current ––– ––– 161
f
(Body Diode) A
ISM Pulsed Source Current ––– ––– 620
Bod
Diode
c
VSD Diode Forward Voltage –– ––– 1.0 V
trr Reverse Recovery Time ––– 39 59 ns
Qrr Reverse Recovery Charge ––– 36 54 nC
ton Forward Turn-On Time
VDS = VGS, ID = 250µA
VDS = 24V, VGS = 0V
VDS = 24V, VGS = 0V, TJ = 125°C
Conditions
14
Max.
1440
12
ƒ = 1.0MHz
ID = 12A
VDS = 15V
Conditions
VGS = 0V, ID = 25A
Reference to 25°C, ID = 1mA
VGS = 10V, ID = 15A
e
VGS = 4.5V, ID = 12A
e
VGS = 20V
VGS = -20V
VDS = 15V, ID = 12A
VDS = 15V, VGS = 0V
VDD = 15V, VGS = 4.5V
e
Clamped Inductive Load
TJ = 25°C, IF = 12A, VDD = 15V
di/dt = 100A/
µ
s
e
TJ = 25°C, IS = 12A, VGS = 0V
e
showing the
integral reverse
p-n junction diode.
Intrinsic turn-on time is negligible (turn-on is dominated by LS+LD)
MOSFET symbol
–––
VGS = 4.5V
Typ.
–––
–––
ID = 12A
VGS = 0V
VDS = 15V
IRLR/U7843PbF
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Fig 4. Normalized On-Resistance
vs. Temperature
Fig 2. Typical Output CharacteristicsFig 1. Typical Output Characteristics
Fig 3. Typical Transfer Characteristics
2.0 3.0 4.0 5.0
VGS, Gate-to-Source Voltage (V)
1
10
100
1000
ID, Drain-to-Source Current (Α)
TJ = 25°C
TJ = 175°C
VDS = 15V
20µs PULSE WIDTH
-60 -40 -20 020 40 60 80 100 120 140 160 180
TJ , Junction Temperature (°C)
0.5
1.0
1.5
2.0
RDS(on) , Drain-to-Source On Resistance
(Normalized)
ID = 30A
VGS = 10V
0.1 110 100
VDS, Drain-to-Source Voltage (V)
0.1
1
10
100
1000
ID, Drain-to-Source Current (A)
2.5V
20µs PULSE WIDTH
Tj = 25°C
VGS
TOP 10V
4.5V
3.7V
3.5V
3.3V
3.0V
2.7V
BOTTOM 2.5V
0.1 110 100
VDS, Drain-to-Source Voltage (V)
1
10
100
1000
ID, Drain-to-Source Current (A)
2.5V
20µs PULSE WIDTH
Tj = 175°C
VGS
TOP 10V
4.5V
3.7V
3.5V
3.3V
3.0V
2.7V
BOTTOM 2.5V
IRLR/U7843PbF
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Fig 8. Maximum Safe Operating Area
Fig 6. Typical Gate Charge vs.
Gate-to-Source Voltage
Fig 5. Typical Capacitance vs.
Drain-to-Source Voltage
Fig 7. Typical Source-Drain Diode
Forward Voltage
110 100
VDS, Drain-to-Source Voltage (V)
100
1000
10000
100000
C, Capacitance (pF)
Coss
Crss
Ciss
VGS = 0V, f = 1 MHZ
Ciss = Cgs + Cgd, Cds SHORTED
Crss = Cgd
Coss = Cds + Cgd
0 20406080
QG Total Gate Charge (nC)
0
2
4
6
8
10
12
VGS, Gate-to-Source Voltage (V)
VDS= 24V
VDS= 15V
ID= 12A
0.0 0.5 1.0 1.5
VSD, Source-toDrain Voltage (V)
0.1
1.0
10.0
100.0
1000.0
ISD, Reverse Drain Current (A)
TJ = 25°C
TJ = 175°C
VGS = 0V
0.1 1.0 10.0 100.0 1000.0
VDS , Drain-toSource Voltage (V)
1
10
100
1000
10000
ID, Drain-to-Source Current (A)
Tc = 25°C
Tj = 175°C
Single Pulse
1msec
10msec
OPERATION IN THIS AREA
LIMITED BY R DS(on)
100µsec
IRLR/U7843PbF
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Fig 11. Maximum Effective Transient Thermal Impedance, Junction-to-Case
Fig 9. Maximum Drain Current vs.
Case Temperature
Fig 10. Threshold Voltage vs. Temperature
25 50 75 100 125 150 175
TC , Case Temperature (°C)
0
40
80
120
160
ID , Drain Current (A)
LIMITED BY PACKAGE
-75 -50 -25 025 50 75 100 125 150 175
TJ , Temperature ( °C )
0.0
0.5
1.0
1.5
2.0
2.5
VGS(th) Gate threshold Voltage (V)
ID = 250µA
1E-006 1E-005 0.0001 0.001 0.01 0.1
t1 , Rectangular Pulse Duration (sec)
0.001
0.01
0.1
1
10
Thermal Response ( Z thJC )
0.20
0.10
D = 0.50
0.02
0.01
0.05
SINGLE PULSE
( THERMAL RESPONSE )
Notes:
1. Duty Factor D = t1/t2
2. Peak Tj = P dm x Zthjc + Tc
Ri (°C/W) τi (sec)
0.5084 0.000392
0.5423 0.011108
τJ
τJ
τ1
τ1τ2
τ2
R1
R1R2
R2
τ
τC
Ci i/Ri
Ci= τi/Ri
IRLR/U7843PbF
6www.irf.com
D.U.T. V
DS
I
D
I
G
3mA
V
GS
.3µF
50K
.2µF
12V
Current Regulator
Same Type as D.U.T.
Current Sampling Resistors
+
-
Fig 13. Gate Charge Test Circuit
Fig 12b. Unclamped Inductive Waveforms
Fig 12a. Unclamped Inductive Test Circuit
tp
V
(BR)DSS
I
AS
Fig 12c. Maximum Avalanche Energy
Vs. Drain Current
R
G
I
AS
0.01
t
p
D.U.T
L
VDS
+
-V
DD
DRIVER
A
15V
20V
VGS
25 50 75 100 125 150 175
Starting TJ, Junction Temperature (°C)
0
1000
2000
3000
4000
5000
6000
EAS, Single Pulse Avalanche Energy (mJ)
I D
TOP 8.6A
9.6A
BOTTOM 12A
Fig 14a. Switching Time Test Circuit
Fig 14b. Switching Time Waveforms
VGS
VDS
90%
10%
td(on) td(off)
trtf
VGS
Pulse Width < 1µs
Duty Factor < 0.1%
VDD
VDS
LD
D.U.T
+
-
IRLR/U7843PbF
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Fig 15. Peak Diode Recovery dv/dt Test Circuit for N-Channel
HEXFET® Power MOSFETs
Circuit Layout Considerations
Low Stray Inductance
Ground Plane
Low Leakage Inductance
Current Transformer
P.W. Period
di/dt
Diode Recovery
dv/dt
Ripple 5%
Body Diode Forward Drop
Re-Applied
Voltage
Reverse
Recovery
Current
Body Diode Forward
Current
V
GS
=10V
V
DD
I
SD
Driver Gate Drive
D.U.T. I
SD
Waveform
D.U.T. V
DS
Waveform
Inductor Curent
D = P. W .
Period
* VGS = 5V for Logic Level Devices
*
+
-
+
+
+
-
-
-
RGVDD
dv/dt controlled by RG
Driver same type as D.U.T.
ISD controlled by Duty Factor "D"
D.U.T. - Device Under Test
D.U.T
Fig 16. Gate Charge Waveform
Vds
Vgs
Id
Vgs(th)
Qgs1 Qgs2 Qgd Qgodr
IRLR/U7843PbF
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Control FET
Special attention has been given to the power losses
in the switching elements of the circuit - Q1 and Q2.
Power losses in the high side switch Q1, also called
the Control FET, are impacted by the Rds(on) of the
MOSFET, but these conduction losses are only about
one half of the total losses.
Power losses in the control switch Q1 are given
by;
Ploss = Pconduction+ Pswitching+ Pdrive+ Poutput
This can be expanded and approximated by;
P
loss =Irms
2×Rds(on )
()
+I×Qgd
ig
×Vin ×f
+I×Qgs 2
ig
×V
in ×f
+Qg×Vg×f
()
+Qoss
2×Vin ×f
This simplified loss equation includes the terms Qgs2
and Qoss which are new to Power MOSFET data sheets.
Qgs2 is a sub element of traditional gate-source
charge that is included in all MOSFET data sheets.
The importance of splitting this gate-source charge
into two sub elements, Qgs1 and Qgs2, can be seen from
Fig 16.
Qgs2 indicates the charge that must be supplied by
the gate driver between the time that the threshold
voltage has been reached and the time the drain cur-
rent rises to Idmax at which time the drain voltage be-
gins to change. Minimizing Qgs2 is a critical factor in
reducing switching losses in Q1.
Qoss is the charge that must be supplied to the out-
put capacitance of the MOSFET during every switch-
ing cycle. Figure A shows how Qoss is formed by the
parallel combination of the voltage dependant (non-
linear) capacitances Cds and Cdg when multiplied by
the power supply input buss voltage.
Synchronous FET
The power loss equation for Q2 is approximated
by;
P
loss =P
conduction +P
drive +P
output
*
P
loss =Irms
2×Rds(on)()
+Qg×Vg×f
()
+Qoss
2×Vin ×f
+Qrr ×Vin ×f
(
)
*dissipated primarily in Q1.
For the synchronous MOSFET Q2, Rds(on) is an im-
portant characteristic; however, once again the im-
portance of gate charge must not be overlooked since
it impacts three critical areas. Under light load the
MOSFET must still be turned on and off by the con-
trol IC so the gate drive losses become much more
significant. Secondly, the output charge Qoss and re-
verse recovery charge Qrr both generate losses that
are transfered to Q1 and increase the dissipation in
that device. Thirdly, gate charge will impact the
MOSFETs’ susceptibility to Cdv/dt turn on.
The drain of Q2 is connected to the switching node
of the converter and therefore sees transitions be-
tween ground and Vin. As Q1 turns on and off there is
a rate of change of drain voltage dV/dt which is ca-
pacitively coupled to the gate of Q2 and can induce
a voltage spike on the gate that is sufficient to turn
the MOSFET on, resulting in shoot-through current .
The ratio of Qgd/Qgs1 must be minimized to reduce the
potential for Cdv/dt turn on.
Power MOSFET Selection for Non-Isolated DC/DC Converters
Figure A: Qoss Characteristic
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D-Pak (TO-252AA) Part Marking Information
D-Pak (TO-252AA) Package Outline
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Note: For the most current drawing please refer to IR website at http://www.irf.com/package/
IRLR/U7843PbF
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I-Pak (TO-251AA) Package Outline
Dimensions are shown in millimeters (inches)
I-Pak (TO-251AA) Part Marking Information
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Note: For the most current drawing please refer to IR website at http://www.irf.com/package/
IRLR/U7843PbF
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Repetitive rating; pulse width limited by
max. junction temperature.
Starting TJ = 25°C, L = 20mH, RG = 25,
IAS = 12A.
Pulse width 400µs; duty cycle 2%.
Notes:
Calculated continuous current based on maximum allowable
junction temperature. Package limitation current is 30A.
When mounted on 1" square PCB (FR-4 or G-10 Material).
For recommended footprint and soldering techniques refer to
application note #AN-994.
Data and specifications subject to change without notice.
This product has been designed and qualified for the Industrial market.
Qualification Standards can be found on IR’s Web site.
IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105
TAC Fax: (310) 252-7903
Visit us at www.irf.com for sales contact information.04/2008
D-Pak (TO-252AA) Tape & Reel Information
Dimensions are shown in millimeters (inches)
TR
16.3 ( .641 )
15.7 ( .619 )
8.1 ( .318 )
7.9 ( .312 )
12.1 ( .476 )
11.9 ( .469 ) FEED DIRECTION FEED DIRECTION
16.3 ( .641 )
15.7 ( .619 )
TRR TRL
NOTES :
1. CONTROLLING DIMENSION : MILLIMETER.
2. ALL DIMENSIONS ARE SHOWN IN MILLIMETERS ( INCHES ).
3. OUTLINE CONFORMS TO EIA-481 & EIA-541.
NOTES :
1. OUTLINE CONFORMS TO EIA-481.
16 mm
13 INCH
Note: For the most current drawing please refer to IR website at http://www.irf.com/package/