Preliminary Datasheet
340kHz, 2A Synchronous DC-DC Buck Converter
General Description
The AP3502E is a 340kHz fixed frequency, current
mode, PWM synchronous buck (step-down) DC-DC
converter, capable of driving a 2A load with high
efficiency, excellent line and load regulation. The
AP3502E exhibits high efficiency at light load. 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.
The AP3502E employs complete protection to ensure
system security. Including output Over Voltage
Protection, input Under Voltage Lock Out,
programmable Soft Start, Over Temperature
Protection and hiccup mode Short Circuit Protection.
This IC is available in SOIC-8 package.
AP3502E
Features
•
•
•
•
•
•
•
•
•
•
•
•
Input Voltage Range: 4.5V to 18V
Fixed 340kHz Frequency
High Efficiency at Light Load
High Efficiency: up to 95%
Output Current: 2A
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
Hiccup Mode SCP
Applications
•
•
•
•
LCD TV
Set Top Box
Portable DVD
Digital Photo Frame
SOIC-8
Figure 1. Package Type of AP3502E
May. 2012
Rev. 1. 3
1
BCD Semiconductor Manufacturing Limited
Preliminary Datasheet
340kHz, 2A Synchronous DC-DC Buck Converter
Pin Configuration
M Package
(SOIC-8)
AP3502E
BS
IN
SW
GND
1
2
3
4
8
7
6
5
SS
EN
COMP
FB
Figure 2. Pin Configuration of AP3502E (Top View)
Pin Description
Pin Number
1
2
3
4
Pin Name
BS
IN
SW
GND
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
5
FB
6
COMP
7
EN
8
SS
May. 2012
Rev. 1. 3
2
BCD Semiconductor Manufacturing Limited
Preliminary Datasheet
340kHz, 2A Synchronous DC-DC Buck Converter
Functional Block Diagram
AP3502E
Figure 3. Functional Block Diagram of AP3502E
Ordering Information
AP3502E
-
Circuit Type
Package
M: SOIC-8
G1: Green
TR: Tape & Reel
Blank: Tube
Package
SOIC-8
Temperature
Range
-40 to 85°C
Part Number
AP3502EM-G1
AP3502EMTR-G1
Marking ID
3502EM-G1
3502EM-G1
Packing Type
Tube
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. 3
3
BCD Semiconductor Manufacturing Limited
Preliminary Datasheet
340kHz, 2A Synchronous DC-DC Buck Converter
Absolute Maximum Ratings (Note 1)
Parameter
IN Pin Voltage
EN Pin Voltage
SW Pin Voltage
BS Pin Voltage
FB Pin Voltage
COMP Pin Voltage
SS Pin Voltage
Thermal Resistance
Operating Junction Temperature
Storage Temperature
Lead Temperature (Soldering, 10sec)
ESD (Human Body Model)
ESD (Machine Model)
AP3502E
Symbol
V
IN
V
EN
V
SW
V
BS
V
FB
V
COMP
V
SS
θ
JA
T
J
T
STG
T
LEAD
V
HBM
V
MM
Value
-0.3 to 20
-0.3 to V
IN
21
-0.3 to V
SW
+6
-0.3 to 6
-0.3 to 6
-0.3 to 6
105
150
-65 to 150
260
2000
200
Unit
V
V
V
V
V
V
V
ºC/W
ºC
ºC
ºC
V
V
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
Input Voltage
Operating Ambient Temperature
Symbol
V
IN
T
A
Min
4.5
-40
Max
18
85
Unit
V
ºC
May. 2012
Rev. 1. 3
4
BCD Semiconductor Manufacturing Limited
Preliminary Datasheet
340kHz, 2A Synchronous DC-DC Buck Converter
Electrical Characteristics
T
A
=25ºC, V
IN
=V
EN
=12V, V
OUT
=3.3V, unless otherwise specified.
Parameter
Symbol
V
IN
I
Q
I
SHDN
V
UVLO
V
HYS
Conditions
Min
4.5
V
FB
=1V, V
EN
=3V
V
EN
=0V
V
IN
Rising
3.65
1.2
0.1
4.00
200
1.5
350
2.2
2.5
210
0.925
1.1
2.7
Typ
Max
18
1.4
10
4.25
Unit
V
mA
µA
V
mV
V
mV
V
mV
V
V
µA
mΩ
mΩ
10
µA
A
mA
kHz
kHz
%
%
V/V
µA/V
A/V
ºC
ºC
ms
µA
AP3502E
SUPPLY VOLTAGE (IN PIN)
Input Voltage
Quiescent Current
Shutdown Supply Current
UNDER VOLTAGE LOCKOUT
Input UVLO Threshold
Input UVLO Hysteresis
ENABLE (EN PIN)
EN Shutdown Threshold Voltage
EN1Shutdown1Threshold1Voltage1Hystere-
sis (Note 3)
EN Lockout Threshold Voltage
EN Lockout Hysteresis
1.1
2
VOLTAGE REFERENCE (FB PIN)
Feedback Voltage
Feedback Over Voltage Threshold
Feedback Bias Current
V
FB
V
FBOV
I
FB
R
DSONH
R
DSONL
I
LEAKH
I
LIMH
I
LIML
f
OSC1
f
OSC2
D
MAX
D
MIN
A
EA
G
EA
G
CS
T
OTSD
T
HYS
t
SS
C4=0.1µF,I
OUT
=500mA
0.907
V
FB
=1V
I
SW
=0.2A/0.7A
I
SW
=-0.2A/-0.7A
V
IN
=18V,V
EN
=V
SW
=0V
2.7
Drain to Source
280
V
FB
=0.85V
V
FB
=1V
-0.1
100
100
0.1
3.5
0
340
90
90
0.943
0.1
MOSFET
High-side Switch On-resistance (Note 2)
Low-side Switch On-resistance (Note 2)
CURRENT LIMIT
High-side Switch Leakage Current
High-side Switch Current Limit
Low-side Switch Current Limit
SWITCHING REGULATOR
Oscillator Frequency
Short Circuit Oscillator Frequency
Max. Duty Cycle
Min. Duty Cycle
400
0
400
800
3.5
160
30
15
5
ERROR AMPLIFIER
Error Amplifier Voltage Gain (Note 3)
Error Amplifier Transconductance
COMP to Current Sense Transconductance
THERMAL SHUTDOWN
Thermal Shutdown (Note 3)
Thermal Shutdown Hysteresis (Note 3)
SOFT START (SS PIN)
Soft-start Time (Note 3)
Soft-start Current
Note 2: R
DSON
=
V
SW1
- V
SW2
I
SW1
- I
SW2
Note 3: Not tested, guaranteed by design.
May. 2012
Rev. 1. 3
5
BCD Semiconductor Manufacturing Limited
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