FAN5353 — 3MHz, 3A Synchronous Buck Regulator
September 2010
FAN5353
3MHz, 3A Synchronous Buck Regulator
Features
3MHz Fixed-Frequency Operation
Best-in-Class Load Transient
3A Output Current Capability
2.7V to 5.5V Input Voltage Range
Adjustable Output Voltage: 0.8V to V
IN
•0.9
Power Good Output
Internal Soft-Start
Input Under-Voltage Lockout (UVLO)
Thermal Shutdown and Overload Protection
12-lead 3x3.5mm MLP
Description
The FAN5353 is a step-down switching voltage regulator that
delivers an adjustable output from an input voltage supply of
2.7V to 5.5V. Using a proprietary architecture with
synchronous rectification, the FAN5353 is capable of
delivering 3A at over 85% efficiency. The regulator operates
at a nominal fixed frequency of 3MHz, which reduces the
value of the external components to 470nH for the output
inductor and 10µF for the output capacitor. Additional output
capacitance can be added without affecting stability if tighter
regulation during transients is required. The regulator
includes an open-drain power good (PGOOD) signal that
pulls low when the output is not in regulation.
In shutdown mode, the supply current drops below 1µA,
reducing power consumption.
FAN5353 is available in a 12-lead 3x3.5mm MLP package.
R2
R1
Applications
Set-Top Box
Hard Disk Drive
Communications Cards
DSP Power
AGND
1
2
3
4
5
6
P1
(GND)
12
11
10
9
8
7
PGOOD
EN
VCC
PVIN
C
IN1
C
IN
R3
FB
VOUT
PGND
PGND
C
OUT
C
VCC
L1
SW
SW
PVIN
Figure 1. Typical Application
Ordering Information
Part Number
FAN5353MPX
Temp. Range
-40 to 85°C
Package
MLP-12, 3x3.5mm
Packing Method
Tape and Reel
© 2009 Fairchild Semiconductor Corporation
FAN5353 • Rev. 1.0.2
www.fairchildsemi.com
FAN5353 — 3MHz, 3A Synchronous Buck Regulator
Table 1. Recommended External Components for 3A Maximum Load Current
Component
L1
Description
470nH nominal
2 pieces
10μF, 6.3V, X5R, 0805
10μF, 6.3V, X5R, 0805
10nF, 25V, X7R, 0402
4.7μF, 6.3V, X5R, 0603
Resistor: 1Ω 0402
Vendor
Vishay
IHLP1616ABER47M01
Coiltronics SD12-R47-R
TDK
VLC5020T-R47N
MURATA LQH55PNR47NT0
GRM21BR60J106M (Murata)
C2012X5R0J106M (TDK)
GRM155R71E103K (Murata)
C1005X7R1E103K (TDK)
GRM188R60J475K (Murata)
C1608X5R0J475K (TDK)
any
Parameter
L
DCR
Typ.
0.47
20
Units
μH
mΩ
C
OUT
C
IN
C
IN1
C
VCC
R3
(1)
C
10.0
μF
C
C
R
10
4.7
1
nF
μF
Ω
Note:
1. R3 is optional and improves IC power supply noise rejection. See Layout recommendations for more information.
Pin Configuration
FB 1
VOUT 2
PGND 3
PGND 4
SW 5
SW 6
P1
(GND)
12 NC
11 PGOOD
10 EN
9 VCC
8 PVIN
7 PVIN
Figure 2. 12-Pin, 3x3.5mm MLP (Top View)
Pin Definitions
Pin #
1
2
3, 4
5, 6
P1
7, 8
9
10
11
12
Name
FB
VOUT
PGND
SW
GND
PVIN
VCC
EN
PGOOD
NC
Description
FB.
Connect to resistor divider. The IC regulates this pin to 0.8V.
VOUT.
Sense pin for VOUT. Connect to COUT.
Power Ground.
Low-side MOSFET is referenced to this pin. CIN and COUT should be returned with a
minimal path to these pins.
Switching Node.
Connect to inductor.
Ground.
All signals are referenced to this pin.
Power Input Voltage.
Connect to input power source. Connect to CIN with minimal path.
IC Bias Supply.
Connect to input power source. Use a separate bypass capacitor CVCC from this pin
to the P1 GND terminal between pins 1 and 12.
Enable.
The device is in shutdown mode when this pin is LOW. Do not leave this pin floating.
Power Good.
This open-drain pin pulls LOW if the output falls out of regulation or is in soft-start.
This pin has no function and should be tied to GND.
Note:
2. P1 is the bottom heat-sink pad. Ground plane should flow through pins 3, 4, 12, and P1 and can be extended through pin
11 if PGOOD’s function is not required to improve IC cooling.
© 2009 Fairchild Semiconductor Corporation
FAN5353 • Rev. 1.0.2
www.fairchildsemi.com
2
FAN5353 — 3MHz, 3A Synchronous Buck Regulator
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
V
IN
SW, PVIN, VCC Pins
Other Pins
V
INOV_SLEW
Maximum Slew Rate of VIN Above 6.5V when PWM is Switching
R
PGOOD
ESD
T
J
T
STG
T
L
Pull-Up Resistance from PGOOD to VCC
Electrostatic Discharge
Protection Level
Junction Temperature
Storage Temperature
Lead Soldering Temperature, 10 Seconds
Human Body Model per JESD22-A114
Charged Device Model per JESD22-C101
IC Not Switching
IC Switching
Min.
-0.3
-0.3
-0.3
1
2
2
–40
–65
Max.
7.0
6.5
V
CC
+ 0.3
15
(3)
Units
V
V
V/ms
KΩ
KV
KV
+150
+150
+260
°C
°C
°C
Note:
3. Lesser of 7V or V
CC
+0.3V.
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
V
CC,
V
IN
V
OUT
I
OUT
L
C
IN
C
OUT
T
A
T
J
Parameter
Supply Voltage Range
Output Voltage Range
Output Current
Inductor
Input Capacitor
Output Capacitor
Operating Ambient Temperature
Operating Junction Temperature
Min.
2.7
0.8
0
Typ.
Max.
5.5
90% Duty Cycle
3
Units
V
V
A
µH
µF
µF
0.47
10
20
-40
-40
+85
+125
°C
°C
Thermal Properties
Symbol
θ
JA
Parameter
Junction-to-Ambient Thermal Resistance
(4)
Min.
Typ.
46
Max.
Units
°C/W
Note:
4. Junction-to-ambient thermal resistance is a function of application and board layout. This data is measured with four-layer
1s2p boards in accordance to JESD51- JEDEC standard. Special attention must be paid not to exceed junction
temperature T
J(max)
at a given ambient temperate T
A
.
© 2009 Fairchild Semiconductor Corporation
FAN5353 • Rev. 1.0.2
www.fairchildsemi.com
3
FAN5353 — 3MHz, 3A Synchronous Buck Regulator
Electrical Characteristics
Minimum and maximum values are at V
IN
= 2.7V to 5.5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at
T
A
= 25°C, V
IN
=5V.
Symbol Parameter
Power Supplies
I
Q
I
SD
V
UVLO
V
UVHYST
Logic Pins
V
IH
V
IL
V
LHYST
I
IN
I
OUTL
I
OUTH
HIGH-Level Input Voltage
LOW-Level Input Voltage
Logic Input Hysteresis Voltage
Input Bias Current
PGOOD Pull-Down Current
PGOOD HIGH Leakage Current
Output Reference DC Accuracy
Measured at FB Pin
V
OUT
DC Accuracy
Load Regulation
Line Regulation
Transient Response
Power Switch and Protection
R
DS(ON)P
R
DS(ON)N
I
LIMPK
T
LIMIT
T
HYST
V
SDWN
P-channel MOSFET On Resistance
N-channel MOSFET On Resistance
P-MOS Peak Current Limit
Thermal Shutdown
Thermal Shutdown Hysteresis
Input OVP Shutdown
Quiescent Current
Shutdown Supply Current
Under-Voltage Lockout Threshold
Under-Voltage Lockout Hysteresis
Conditions
I
LOAD
= 0, V
OUT
=1.2V
EN = GND
V
IN
Rising
V
IN
Falling
Min.
Typ.
14
0.1
2.83
Max.
Units
mA
3.0
2.95
2.40
μA
V
V
mV
V
2.10
2.30
530
1.05
0.4
100
Input tied to GND or V
IN
V
PGOOD
= 0.4V
V
PGOOD
= V
IN
T
A
= 25°C
At VOUT pin W.R.T. Calculated
Value, I
LOAD
= 500mA
I
OUT(DC)
= 0 to 3A
2.7V
≤
V
IN
≤
5.5V, I
OUT(DC)
=
1.5A
I
LOAD
step 0.1A to 1.5A, t
r
= t
f
=
100ns, V
OUT
=1.2V
0.792
0.788
1.6%
–0.03
0.01
+20
0.01
0.800
0.800
0.01
1.00
1
1
0.808
0.812
+1.6
V
mV
μA
mA
μA
V
V
%
%/A
%/V
mV
VOUT Regulation
V
REF
V
REG
Δ
V
OUT
Δ
I
LOAD
Δ
V
OUT
Δ
V
IN
60
40
3.75
4.55
150
20
Rising Threshold
Falling Threshold
5.50
2.7
R
LOAD
> 5Ω, to V
OUT
= 1.2V
R
LOAD
> 5Ω, to V
OUT
= 1.8V
6.2
5.85
3.0
210
340
10
3.3
250
420
5.50
mΩ
mΩ
A
°C
°C
V
V
MHz
μs
μs
V/ms
Frequency Control
f
SW
Soft-Start
t
SS
V
SLEW
Regulator Enable to Regulated V
OUT
Soft-Start V
OUT
Slew Rate
Oscillator Frequency
© 2009 Fairchild Semiconductor Corporation
FAN5353 • Rev. 1.0.2
www.fairchildsemi.com
4
FAN5353 — 3MHz, 3A Synchronous Buck Regulator
Typical Characteristics
Unless otherwise specified, V
IN
= 5V, V
OUT
= 1.2V, circuit of Figure 1, and components per Table 1.
100%
90%
80%
70%
Efficiency
Efficiency
60%
50%
40%
30%
20%
10%
0%
1
10
I
LOAD
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
100
1000
10000
1
10
I
LOAD
100
1000
10000
Output Current (mA)
VIN = 3.3V
VIN = 5V
VIN = 3.3V
VIN = 5V
Output Current (mA)
Figure 3. Efficiency vs. I
LOAD
at V
OUT
= 1.2V
100%
90%
80%
70%
Efficiency
Efficiency
60%
50%
40%
30%
20%
10%
0%
1
10
100
1000
10000
I
LOAD
Output Current (mA)
VIN = 3.3V
VIN = 5V
Figure 4. Efficiency vs. I
LOAD
at V
OUT
= 1.8V
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
1
10
100
1000
10000
I
LOAD
Output Current (mA)
VIN = 4.2V
VIN = 5V
Figure 5. Efficiency vs. I
LOAD
at V
OUT
= 2.5V
1
0.9
Figure 6. Efficiency vs. I
LOAD
at V
OUT
= 3.3V
16
15
Quiescent Current (mA)
14
13
12
11
10
9
8
85°C
25°C
–40°C
0.8
Supply Current (
μ
A)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
2.7
3.2
3.7
4.2
Input Voltage(V)
4.7
5.2
85°C
25°C
‐40°C
2.7
3.2
3.7
4.2
4.7
5.2
VIN Input Voltage (V)
Figure 7. Shutdown Supply Current vs. V
IN
, EN to 0V
Figure 8. Quiescent Current vs. V
IN
, No Load
© 2009 Fairchild Semiconductor Corporation
FAN5353 • Rev. 1.0.2
www.fairchildsemi.com
5
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