Diodes AP3440 User Manual
AP3440
Document number: DS36691 Rev. 2 - 2
1 of 15
www.diodes.com
March 2014
© Diodes Incorporated
AP3440
A Product Line of
Diodes Incorporated
NEW PRODUCT
Description
The AP3440 is a current mode, PWM synchronous buck (step-down)
DC-DC converter, capable of driving a 4A load with high efficiency,
excellent line and load regulation.
The device integrates two N-channel power MOSFETs with low onresistance. Current mode control provides fast transient response and
cycle-by-cycle current limit.
The switching frequency of AP3440 can be programmable from
200kHz to 2MHz, which allows small-sized components, such as
capacitors and inductors. A standard series of inductors from several
different manufacturers are available. This feature greatly simplifies
the design of switch-mode power supplies.
Under voltage lockout is internally set at 2.6V, but can be increased
by programming the threshold with a resistor network on the enable
pin. The output voltage startup ramp is controlled by the soft-start pin.
An open drain power good signal indicates the output is within 93% to
107% of its nominal voltage.
The AP3440 is available in U-QFN3030-16 package.
Applications
Low-voltage, High-density Power Systems
Point of Load Regulation for High Performance DSPs, FPGAs,
ASICs and Microprocessors
Broadband, Networking and Optical Communications
Infrastructure
Pin Assignments
(Top View)
VIN
VIN
GND
GND
AGND
FB
COMP
RT/CLK
SS
SW
SW
SW
BOOT
PGD
EN
VIN
E P
5 6 7 8
1
2
3
4 9
12
Pin 1 Mark
11
10
13141516
U-QFN3030-16
Features
Input Voltage Range: 2.95V to 5.5V
0.8V Reference Voltage with ±3% Precision
Two 30m(Typical) MOSFETs for High Efficiency at 4A Load
High Efficiency: Up to 94%
Output Current: 4A
Programmable Frequency:200kHz to 2MHz
Current Mode Control
Synchronizes to External Clock
Adjustable Soft-start
Soft Start-up into Pre-biased Output
UV and OV Power Good Output
Built-in Over Current Protection
Built-in Thermal Shutdown Function
Programmable UVLO Function
Built-in Over Voltage Protection
Thermally Enhanced 3mm×3mm 16-pin U-QFN3030-16
Totally Lead-free & Fully RoHS Compliant (Note1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
4A, 2MHZ HIGH PERFORMANCE SYNCHRONOUS BUCK CONVERTER
Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
AP3440
Document number: DS36691 Rev. 2 - 2
2 of 15
www.diodes.com
March 2014
© Diodes Incorporated
AP3440
A Product Line of
Diodes Incorporated
NEW PRODUCT
VIN
VIN
VIN
PGD
EN
COMP
SS
RT/CLK
SW
SW
SW
BOOT
FB
GND
GND
AGND
L1 1.5mH
V
OUT
=1.8V
R6 12.5kΩ
R7
10kΩ
VIN=5V
R4
100kΩ
16
1
2
14
15
7
8
9
10
11
12
13
6
4
5
3
C5
Optional
C2
C7
0.01mF
C4
2.7nF
R3
7.5kΩ
R5
180kΩ
R1
R2
AP3440
C3
C9
22mF
C1
10mF 0.1mF
C8
22mF
U1
C6
0.1mF
R8 2.2Ω
(Optional)
C10 2.2nF
(Optional)
Pin Number
Pin Name
Function
1,2,16
VIN
Supply input pin. A capacitor should be connected between the VIN and GND pin to keep the
DC input voltage constant
3,4
GND
Power ground. This pin should be electrically connected to the power pad under the IC
5
AGND
Analog ground. This pin should be electrically connected to GND close to the device
6
FB
Feedback pin. Inverting node of the transconductance error amplifier
7
COMP
Compensation pin. This pin is the output of the transconductance error amplifier and the input
to the current comparator. Connect external compensation elements to this pin to stabilize the
control loop
8
RT/CLK
Resistor timing or external clock input pin
9
SS
Soft-start pin. An external capacitor connected to this pin sets the output voltage rise time. This
pin can also be used for tracking
10,11,12
SW
Internal power switch output pin. This pin is connected to the inductor and bootstrap capacitor
13
BOOT
Bootstrap pin. A bootstrap capacitor is connected between the BOOT pin and SW pin. The
voltage across the bootstrap capacitor drives the internal high-side power MOSFET
14
PGD
Power good indicator output. Asserts low if output voltage is low due to thermal shutdown,
over-current, over/under-voltage or EN shut down
15
EN
Enable pin, internal pull-up current source. Pull below 1.2V to disable. Float to enable. Can be
used to set the on/off threshold (adjust UVLO) with two additional resistors
EP
Exposed Thermal Pad
Exposed Pad can be connected to GND, for best thermal performance thermal vias are
recommended under the package
Typical Applications Circuit
Pin Description
AP3440
Document number: DS36691 Rev. 2 - 2
3 of 15
www.diodes.com
March 2014
© Diodes Incorporated
AP3440
A Product Line of
Diodes Incorporated
NEW PRODUCT
Functional Block Diagram
AP3440
Document number: DS36691 Rev. 2 - 2
4 of 15
www.diodes.com
March 2014
© Diodes Incorporated
AP3440
A Product Line of
Diodes Incorporated
NEW PRODUCT
Symbol
Parameter
Rating
Unit
VIN
VIN Pin Voltage
-0.3 to 6.5
V
VEN
EN Pin Voltage
-0.3 to 6.5
V
VSW
SW Pin Voltage
-0.3 to VIN+0.3
V
VFB
FB Pin Voltage
-0.3 to 6.5
V
V
COMP
COMP Pin Voltage
-0.3 to 6.5
V
V
PGD
PGD Pin Voltage
-0.3 to 6.5
V
V
RT/CLK
RT/CLK Pin Voltage
-0.3 to 6.5
V
VSS
SS Pin Voltage
-0.3 to 6.5
V
JA
Thermal Resistance
70
ºC/W
TJ
Operating Junction Temperature
-40 to +125
ºC
T
STG
Storage Temperature
-65 to +150
ºC
T
LEAD
Lead Temperature (Soldering, 10sec)
+260
ºC
—
ESD(Machine Model)
200
V
—
ESD(Human Body Model)
2000
V
Symbol
Parameter
Min
Max
Unit
VIN
Input Voltage
2.95
5.5
V
I
OUT(MAX)
Maximum Output Current
4 — A
TA
Operating Ambient Temperature
-40
+85
ºC
Symbol
Parameters
Conditions
Min
Typ
Max
Unit
SUPPLY VOLTAGE (VIN PIN)
VIN
Input Voltage
—
2.95 — 5.5
V
IQ
Quiescent Current
VFB=0.9V, VIN=5V,
TA=+25ºC, RT=400k
—
360
575
μA
I
SHDN
Shutdown Supply Current
VEN=0V,TA=+25C,
2.95V≤V
IN
≤5.5V
—
2 5 μA
ENABLE AND UVLO (EN PIN)
V
EN_H
Enable Threshold
Rising
1.16
1.25
1.37
V
V
EN_L
Falling — 1.18 — V
V
UVLO
Internal Under Voltage
Lockout Threshold
—
—
2.6
2.8
V
V
HYS
Internal Under Voltage
Hysteresis
—
—
150 — mV
Absolute Maximum Ratings (Note 4)
Note 4: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “Recommended Operating Conditions” is not implied.
Exposure to “Absolute Maximum Ratings” for extended periods may affect device reliability.
Recommended Operating Conditions
Electrical Characteristics (@V
over full operating temperature range from -40 to +85ºC.)
=2.95 to 5.5V, TA=+25ºC, unless otherwise specified. Specifications with boldface type apply
IN
AP3440
Document number: DS36691 Rev. 2 - 2
5 of 15
www.diodes.com
March 2014
© Diodes Incorporated
AP3440
A Product Line of
Diodes Incorporated
NEW PRODUCT
Symbol
Parameters
Conditions
Min
Typ
Max
Unit
VOLTAGE REFERENCE (FB PIN)
V
REF
Voltage Reference
2.95V≤V
IN
≤5.5V
0.779
0.803
0.827
V
MOSFET
R
ON_H
High Side Switch Onresistance
V
BOOT-SW
=5V
—
30
60
m
V
BOOT-SW
=2.95V
—
44
70
m
R
ON_L
Low Side Switch Onresistance
VIN=5V
—
30
60
m
VIN=2.95V
—
44
70
mΩ
CURRENT LIMIT
I
LIMIT
Current Limit Threshold
—
4.2
7.0 — A
THERMAL SHUTDOWN
T
TSD
Thermal Shutdown
—
—
140
—
C
—
Hysteresis
—
—
20
—
C
TIMING RESISTOR AND EXTERNAL CLOCK (RT/CLK PIN)
—
Switching Frequency Range
(RT Mode)
—
200 — 2000
kHz
—
Switching Frequency Range
(CLK Mode)
—
300 — 2000
kHz
fS
Switching Frequency
RT=400k
400
500
600
kHz
—
Minimum CLK Pulse Width
—
75
—
—
ns
—
RT/CLK Voltage
RT=400k
—
0.5 — V
—
RT/CLK High Threshold
—
—
1.6
2.2
V
—
RT/CLK Low Threshold
—
0.4
0.6 — V
BOOT (BOOT PIN)
R
BOOT
BOOT Charge Resistor
VIN=5V
—
16
— —
BOOT-SW UVLO
VIN=2.95V
—
2.2 — V
SOFT START (SS PIN)
ISS
Charge Current
VSS=0.4V
— 2 —
mA
VSS
SS to Reference Crossover
98% Nominal
—
1.1 — V
POWER GOOD (PGD PIN)
V
FB_TH
Feedback Threshold
VFB Falling (Fault)
—
91
—
%V
REF
VFB Rising (Good)
—
93
—
VFB Rising (Fault)
—
107
—
VFB Falling (Good)
—
105
—
Electrical Characteristics (Cont.) (@V
apply over full operating temperature range from -40 to +85ºC.)
=2.95 to 5.5V, TA=+25ºC, unless otherwise specified. Specifications with boldface type
IN
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