Diodes AP3203 User Manual
380kHz, 3A Asynchronous DC - DC Buck Converter AP3203
Preliminary Datasheet
General Description
The AP3203 is a 380kHz fixed frequency, current
mode, PWM 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 switch with
low on-resistance. The current mode control provides
fast transient response and cycle-by-cycle current
limit.
A standard series of inductors are available from
several different manufacturers optimized for use
with the AP3203. This feature greatly simplifies the
design of switch-mode power supplies.
This IC is available in PSOP-8 package.
Features
• Input Voltage Range: 4.75V to 18V
• Fixed 380kHz Frequency
• High Efficiency: up to 93%
• 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
• Portable DVD
• DPF
• LCD-TV
• STB
Figure 1. Package Type of AP3203
PSOP-8
Mar. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited
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Preliminary Datasheet
380kHz, 3A Asynchronous DC - DC Buck Converter AP3203
Pin Configuration
MP Package
(PSOP-8)
Figure 2. Pin Configuration of AP3203 (Top View)
Pin Description
Pin Number Pin Name Function
Bootstrap pin. A bootstrap capacitor is connected between the BS pin
1
2
3
4
5
6
7
8
BS
IN
SW
GND Ground pin
FB
COMP
EN
SS
and SW pin. The voltage across the bootstrap capacitor drives the
internal high-side NMOS switch
Supply input pin. A capacitor should be connected between the IN pin
and GND pin to keep the DC input voltage constant
Power switch output pin. This pin is connected to the inductor and
bootstrap capacitor
Feedback pin. This pin is connected to an external resistor divider to
program the system output voltage. When the FB pin voltage exceeds
20% of the nominal regulation value of 1.222V, the over voltage
protection is triggered. When the FB pin voltage is below 0.6V, 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. Forcing this pin above 1.5V or set this pin floating
enables the IC. Forcing this pin below 0.5V shuts down the IC. When
the IC is in shutdown mode, all functions are disabled to decrease the
supply current below 1µA
Soft-start control input. 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 10ms. To disable the soft-start
feature, leave SS disconnected
Mar. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited
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Preliminary Datasheet
380kHz, 3A Asynchronous DC - DC Buck Converter AP3203
Functional Block Diagram
2
IN
V
A
B
Current
Sense
Amplifier
S
R
PWM
Comparator
1.3V
5V
1
M1
Q
Q
V
B
0.12
3
M2
10
4
EN
7
Internal
Pull High
Shutdown
Comparator
0.4/1.5V
Internal Bias
and Regulator
Oscillator
90k/380k
V
SLOP COMP
CLK
BS
SW
GND
Short
Protection
Comparator
0.6
1.222
5
FB
Error
Amplifier
COMP
6 A
6
8
SS
Figure 3. Functional Block Diagram of AP3203
Ordering Information
AP3203 -
Circuit Type
Package
MP: PSOP-8
Package
PSOP-8 -40 to 85ºC
BCD Semiconductor's Pb-free products, as designated with "G1" suffix in the part number, are RoHS compliant
and green.
Temperature
Range
Part Number Marking ID Packing Type
AP3203MP-G1 3203MP-G1 Tube
AP3203MPTR-G1 3203MP-G1 Tape & Reel
G1: Green
TR: Tape & Reel
Blank: Tube
Mar. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited
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Preliminary Datasheet
380kHz, 3A Asynchronous DC - DC Buck Converter AP3203
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
COMP Pin Voltage V
SS Pin Voltage VSS -0.3 to 6 V
Thermal Resistance
Operating Junction Temperature TJ 150 ºC
Storage Temperature T
Lead Temperature (Soldering, 10sec) T
ESD (Machine Model) 200 V
ESD (Human Body Model) 2000 V
-0.3 to 6 V
COMP
θJA
-65 to 150 ºC
STG
260 ºC
LEAD
105 ºC/W
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 4.75 18 V
Maximum Output Current I
Operating Ambient Temperature TA -40 85 ºC
(Max) 3 A
OUT
Mar. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited
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