BCDSEMI AP3503MP-G1

Data Sheet
340kHz, 3A Synchronous DC-DC Buck Converter
General Description
Features
The AP3503 is a 340kHz fixed frequency, current
mode, PWM synchronous buck (step-down) DC-DC
converter, capable of driving a 3A load with high
efficiency, excellent line and load regulation. The
device integrates N-channel power MOSFET
switches with low on-resistance. Current mode
control provides fast transient response and
cycle-by-cycle current limit.
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The AP3503 employs complete protection to ensure
system security. Including output Over Voltage
Protection, input Under Voltage LockOut,
programmable
soft-start,
Over
Temperature
Protection to safeguard the circuit.
AP3503
Input Voltage Range: 4.5V to 18V
Fixed 340kHz Frequency
High Efficiency: up to 95%
Output Current: 3A
Current Mode Control
Built-in Over Current Protection
Built-in Thermal Shutdown Function
Built-in UVLO Function
Built-in Over Voltage Protection
Programmable Soft-start
Applications
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This IC is available in PSOP-8 package.
LCD TV
Set Top Box
Portable DVD
Digital Photo Frame
PSOP-8
Figure 1. Package Type of AP3503
May. 2012
Rev. 1. 7
BCD Semiconductor Manufacturing Limited
1
Data Sheet
340kHz, 3A Synchronous DC-DC Buck Converter
AP3503
Pin Configuration
MP Package
(PSOP-8)
1
8
2
7
3
6
4
5
Figure 2. Pin Configuration of AP3503 (Top View)
Pin Description
Pin Number
Pin Name
1
BS
2
IN
3
SW
4
GND
5
FB
6
COMP
7
EN
8
SS
EP
May. 2012
Function
Bootstrap pin. A bootstrap capacitor is connected between the BS pin
and SW pin. The voltage across the bootstrap capacitor drives the
internal high-side power MOSFET
Supply power input pin. A capacitor should be connected between the
IN pin and GND pin to keep the input voltage constant
Power switch output pin. This pin is connected to the inductor and
bootstrap capacitor
Ground pin
Feedback pin. This pin is connected to an external resistor divider to
program the system output voltage. When the FB pin voltage exceeds
1.1V, the over voltage protection is triggered. When the FB pin
voltage is below 0.3V, the oscillator frequency is lowered to realize
short circuit protection
Compensation pin. This pin is the output of the transconductance
error amplifier and the input to the current comparator. It is used to
compensate the control loop. Connect a series RC network from this
pin to GND. In some cases, an additional capacitor from this pin to
GND pin is required
Control input pin. EN is a digital input that turns the regulator on or
off. Drive EN high/low to turn on/off the regulator. Pull up with
100kΩ resistor for automatic startup
Soft-start control input pin. SS controls the soft-start period. Connect
a capacitor from SS to GND to set the soft-start period. A 0.1µF
capacitor sets the soft-start period to 15ms. To disable the soft-start
feature, leave SS unconnected
Exposed pad. It should be connected to GND in PCB layout
Rev. 1. 7
BCD Semiconductor Manufacturing Limited
2
Data Sheet
340kHz, 3A Synchronous DC-DC Buck Converter
AP3503
Functional Block Diagram
2
IN
SHUTDOWN
COMPARATOR
1.5V
VA
INTERNAL
REGULATOR
0.3V
VB
CURRENT
SENSE
AMPLIFIER
SLOP
COMP
VA
+
OSCILLATOR
SCP
1
90 k/340k
BS
M1
CLK
EN
LOCK
COMPARATOR
7
S
Q
R
Q
3
PWM
COMPARATOR
SW
M2
2.5V
VB
4
1.3V
6 A
SS
8
GND
EA
5
0. 925V
FB
6
COMP
Figure 3. Functional Block Diagram of AP3503
Ordering Information
AP3503
-
Circuit Type
G1: Green
Package
MP: PSOP-8
Package
Temperature
Range
PSOP-8
-40 to 85°C
TR: Tape & Reel
Blank: Tube
Part Number
Marking ID
Packing Type
AP3503MP-G1
3503MP-G1
Tube
AP3503MPTR-G1
3503MP-G1
Tape & Reel
BCD Semiconductor's Pb-free products, as designated with "G1" suffix in the part number, are RoHS compliant
and green.
May. 2012
Rev. 1. 7
BCD Semiconductor Manufacturing Limited
3
Data Sheet
340kHz, 3A Synchronous DC-DC Buck Converter
AP3503
Absolute Maximum Ratings (Note 1)
Parameter
Symbol
Value
Unit
IN Pin Voltage
VIN
-0.3 to 20
V
EN Pin Voltage
VEN
-0.3 to VIN
V
SW Pin Voltage
VSW
21
V
BS Pin Voltage
VBS
-0.3 to VSW+6
V
FB Pin Voltage
VFB
-0.3 to 6
V
VCOMP
-0.3 to 6
V
SS Pin Voltage
VSS
-0.3 to 6
V
Thermal Resistance
θJA
60
ºC/W
Operating Junction Temperature
TJ
150
ºC
Storage Temperature
TSTG
-65 to 150
ºC
Lead Temperature (Soldering, 10sec)
TLEAD
260
ºC
ESD (Human Body Model)
VHBM
2000
V
ESD (Machine Model)
VMM
200
V
COMP Pin Voltage
Note 1: 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
Parameter
Symbol
Min
Max
Unit
Input Voltage
VIN
4.5
18
V
Operating Ambient Temperature
TA
-40
85
ºC
May. 2012
Rev. 1. 7
BCD Semiconductor Manufacturing Limited
4
Data Sheet
340kHz, 3A Synchronous DC-DC Buck Converter
AP3503
Electrical Characteristics
TA=25ºC, VIN=VEN=12V, VOUT=3.3V, unless otherwise specified.
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
1.2
0.1
18
1.4
10
V
mA
µA
SUPPLY VOLTAGE (IN PIN)
Input Voltage
Quiescent Current
Shutdown Supply Current
VIN
IQ
ISHDN
4.5
VFB=1V,VEN=3V
VEN=0V
UNDER VOLTAGE LOCKOUT
Input UVLO Threshold
Input UVLO Hysteresis
VUVLO
VHYS
VIN Rising
3.65
4.00
200
4.25
V
mV
1.1
1.5
2
V
ENABLE (EN PIN)
EN Shutdown Threshold Voltage
EN Shutdown Threshold Voltage Hysteresis
(Note 2)
EN Lockout Threshold Voltage
EN Lockout Hysteresis
350
mV
2.2
2.5
210
2.7
V
mV
0.907
0.925
1.1
0.943
V
V
µA
VOLTAGE REFERENCE (FB PIN)
Feedback Voltage
Feedback Over Voltage Threshold
Feedback Bias Current
VFB
VFBOV
IFB
VFB=1V
RDSONH
RDSONL
ISW=0.2A/0.7A
ISW=-0.2A/-0.7A
ILEAKH
ILIMH
ILIML
VIN=18V,VEN=VSW=0V
-0.1
0.1
MOSFET
High-side Switch On-resistance(Note 3)
Low-side Switch On-resistance(Note 3)
100
100
mΩ
mΩ
CURRENT LIMIT
High-side Switch Leakage Current
High-side Switch Current Limit
Low-side Switch Current Limit
4.3
From drain to Source
0.1
5.6
1.4
10
µA
A
A
340
90
90
400
kHz
kHz
%
%
SWITCHING REGULATOR
Oscillator Frequency
Short Circuit Oscillator Frequency
Max. Duty Cycle
Min. Duty Cycle
fOSC1
fOSC2
DMAX
DMIN
280
VFB=0.85V
VFB=1V
0
ERROR AMPLIFIER
Error Amplifier Voltage Gain (Note 2)
Error Amplifier Transconductance
COMP to Current Sense Transconductance
AEA
GEA
GCS
400
800
5.2
V/V
µA/V
A/V
TOTSD
THYS
160
20
ºC
ºC
CSS=0.1µF
15
ms
VSS=0V
6
µA
THERMAL SHUTDOWN
Thermal Shutdown (Note 2)
Thermal Shutdown Hysteresis (Note 2)
SOFT START (SS PIN)
Soft-start Time (Note 2)
Soft-start Current
tSS
Note 2: Not tested, guaranteed by design.
Note 3: RDSON=
May. 2012
VSW1 - VSW2
.
ISW1 - ISW2
Rev. 1. 7
BCD Semiconductor Manufacturing Limited
5
Data Sheet
340kHz, 3A Synchronous DC-DC Buck Converter
AP3503
Typical Performance Characteristics
TA=25ºC, VIN=12V, VOUT=3.3V, unless otherwise noted.
1.4
100
90
1.3
Quiescent Current (mA)
80
Efficiency (%)
70
60
50
o
VOUT=3.3V, TA=25 C, L=10µH
VIN=5V
VIN=12V
40
30
1.2
1.1
1.0
20
10
0.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
0.9
-50
3.2
-25
0
Output Current (A)
75
100
125
150
Figure 5. Quiescent Current vs. Case Temperature
1.2
3.6
1.1
3.5
1.0
3.4
Output Voltage (V)
Feedback Voltage (V)
50
o
Figure 4. Efficiency vs. Output Current
0.9
0.8
3.3
3.2
3.1
0.7
0.6
-50
25
Case Temperature ( C)
3.0
0.0
-25
0
25
50
75
100
125
150
0.4
0.8
1.2
1.6
2.0
2.4
2.8
3.2
Output Current (A)
o
Case Temperature ( C)
Figure 6. Feedback Voltage vs. Case Temperature
May. 2012
Figure 7. Output Voltage vs. Output Current
Rev. 1. 7
BCD Semiconductor Manufacturing Limited
6
Data Sheet
340kHz, 3A Synchronous DC-DC Buck Converter
AP3503
Typical Performance Characteristics (Continued)
TA=25ºC, VIN=12V, VOUT=3.3V, unless otherwise noted.
160
180
Low-side Switch On-resistance (mΩ)
High-side Switch On-resistance (mΩ)
200
160
140
120
100
80
60
40
-60
-40
-20
0
20
40
60
80
100
120
140
120
100
80
60
40
-60
140
-40
-20
0
20
40
60
80
100
120
140
o
o
Case Temperature ( C)
Case Temperature ( C)
Figure 8. High-side Switch On-resistance
vs. Case Temperature
Figure 9. Low-side Switch On-resistance
vs. Case Temperature
VIN_AC
200mV/div
VOUT_AC
200mV/div
VOUT_AC
20mV/div
IL
2A/div
IOUT
1A/div
VSW
10V/div
Time
Time
4µs/div
Figure 10. Output Ripple (IOUT=3A)
May. 2012
200µs/div
Figure 11. Load Transient (IOUT =1.5A to 3A)
Rev. 1. 7
BCD Semiconductor Manufacturing Limited
7
Data Sheet
340kHz, 3A Synchronous DC-DC Buck Converter
AP3503
Typical Performance Characteristics (Continued)
TA=25ºC, VIN=12V, VOUT=3.3V, unless otherwise noted.
VEN
2V/div
VEN
2V/div
VSS
2V/div
VSS
2V/div
VOUT
2V/div
VOUT
2V/div
IL
2A/div
IL
2A/div
Time
10ms/div
Time
Figure 12. Enable Turn on Characteristic
(VIN=12V, VEN=3.3V, VOUT=3.3V, IL=3A)
Figure 13. Enable Turn off Characteristic
(VIN=12V, VEN=3.3V, VOUT=3.3V, IL=3A)
VOUT
2V/div
VOUT
2V/div
IL
2A/div
IL
2A/div
Time
Time
40µs/div
Figure 14. Short Circuit Protection (IOUT=0A)
May. 2012
200µs/div
40µs/div
Figure 15. Short Circuit Recovery (IOUT=0A)
Rev. 1. 7
BCD Semiconductor Manufacturing Limited
8
Data Sheet
340kHz, 3A Synchronous DC-DC Buck Converter
AP3503
Typical Application
Input Voltage=12V
R4
100k
2
Output Voltage=3.3V
L 10µH
C4
10nF
3
4
C22
C21
22µF/25V 22µF/25V
BS
IN
SW
SS
AP3503
1
EN
COMP
GND
FB
C12
10µF/25V
8
C5
0.1µF
7
C6
Optional
6
C3
3.3nF
5
R2
D1
Optional
C11
10µF/25V
R3
13k
10k
R1
26.1k
Figure 16. Typical Application of AP3503
May. 2012
Rev. 1. 7
BCD Semiconductor Manufacturing Limited
9
Data Sheet
340kHz, 3A Synchronous DC-DC Buck Converter
AP3503
Mechanical Dimensions
Unit: mm(inch)
3.202(0.126)
3.402(0.134)
PSOP-8
May. 2012
Rev. 1. 7
BCD Semiconductor Manufacturing Limited
10
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