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

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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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Preliminary Datasheet

380kHz, 3A Asynchronous DC - DC Buck Converter AP3203

Electrical Characteristics

VIN=VEN=12V, V
the full operating temperature rang (T

Parameter Symbol Conditions Min Typ Max Unit

Input Voltage VIN 4.75 18 V

Quiescent Current IQ

Shutdown Supply Current I

Feedback Voltage VFB

Feedback Over Voltage
Threshold

Feedback SCP Voltage Threshold V

Feedback Bias Current IFB VFB= 1V -0.1 0.1

Upper Switch On-resistance R

Lower Switch On-resistance R

High-side Switch Leakage
Current

High-side Switch Current Limit I

Low-side Switch Current Limit I

EN Pin Threshold

EN Pull-up Current I

Input UVLO Threshold V

Input UVLO Hysteresis V

Oscillator Frequency f

Short Circuit Oscillator
Frequency

Maximum Duty Cycle D

Minimum Duty Cycle D

Error Amplifier Voltage Gain (Note 3) AEA 400 V/V

=3.3V, TA=25

OUT

o

C, unless otherwise specified. And those in boldface type apply over

=-40ºC to +85ºC).

A

=2V,

V

EN

=1.35V

V

FB

VEN=0V 1 10

SHDN

V

1.48 V

FBOV

0.6 V

FB_SCP

1.0 1.5 mA

µA

1.185 1.222 1.258

V

µA

ISW=0.5A

DSONH

ISW=0.05A

DSONL

=18V, VEN=0V

V

I

LEAKH

LIMH

LIML

V

V

EN_PH

UVLO

OSC1

f

OSC2

ENH

ENL

HYS

MAX

MIN

IN

V

=0V

SW

0.1 10

4 5.2 A

From Drain to
Source

0.15 A

1.5 V

0.5 V

VEN=0V 1.0

VIN Rising 3.55 3.85 4.15 V

0.3 V

380 kHz

80 kHz

VFB=1.0V 90 %

VFB=1.35V 0 %

0.12

10

Ω

Ω

µA

µA

Error Amplifier Transconductance GEA 700 950 1200

COMP to Current Sense
Transconductance

Thermal Shutdown (Note 3) T

Thermal Shutdown Hysteresis (Note

3)

Soft-start Time (Note 3) tSS

5.4 A/V

G

CS

160 ºC

OTSD

30 ºC

T

HYS

C4=0.1µF,
I

=500mA

OUT

10 ms

Soft-start Current ISS 6

µA/V

µA

Mar. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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Preliminary Datasheet

380kHz, 3A Asynchronous DC - DC Buck Converter AP3203

VV

−

Note 2:

R

DSON

=

2SW1SW

II

−

2SW1SW

Note 3: Not tested, guaranteed by design.

Typical Performance Characteristics

T

=25ºC, VIN=12V, V

A

100

90
80

70
60
50
40

Efficiency (%)

30
20

10

0

0.00.51.01.52.02.53.0

=3.3V, unless otherwise noted.

OUT

VIN=12V
VIN=5V

Output Current (A)

1.40

1.35

1.30

1.25

1.20

1.15

1.10

1.05

1.00

0.95

0.90

Quiescent Current (mA)

0.85

0.80

0.75

0.70

-60 -40 -20 0 20 40 60 80 100 120 140

Temperature (oC)

Figure 4. Efficiency vs. Output Current Figure 5. Quiescent Current vs. Temperature

3.50

3.45

3.40

3.35

3.30

3.25

3.20

3.15

Output Voltage (V)

3.10

3.05

3.00

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Output Current (A)

1.30

1.28

1.26

1.24

1.22

1.20

1.18

1.16

Feedback Volage (V)

1.14

1.12

1.10

-60 -40 -20 0 20 40 60 80 100 120 140

Temperature (oC)

Figure 6. Output Voltage vs. Output Current Figure 7. Feedback Voltage vs. Temperature

Mar. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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Preliminary Datasheet

380kHz, 3A Asynchronous DC - DC Buck Converter AP3203

Typical Performance Characteristics (Continued)

TA=25ºC, VIN=12V, V

=3.3V, unless otherwise noted.

OUT

170
160
150
140
130
120
110
100

90
80
70

High-side Switch On-resistance (mΩ)

60

-60 -40 -20 0 20 40 60 80 100 120 140

Temperature (oC)

18

16

14

12

10

8

Low-side Switch On-resistance (Ω)

6

-40 -20 0 20 40 60 80 100 120 140

Temperature (oC)

Figure 8. R

vs. Temperature Figure 9. R

DSONH

20mV/div

1A/div

V

OUT(AC)

I

L

VSW

5V/div

Figure 10. Output Ripple Figure 11. Load Transient

=12V,V

(V

IN

Time 10ms/div

Time 2µs/div

OUT

=3.3V, I

I

L

1A/div

V

=3A) (VIN=12V, V

OUT

OUT(AC)

200mV/

vs. Temperature

DSONL

Time 400µs/div

=3.3V, I

OUT

OUT

=2A to 3A)

Mar. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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Preliminary Datasheet

380kHz, 3A Asynchronous DC - DC Buck Converter AP3203

Typical Performance Characteristics (Continued)

TA=25ºC, VIN=12V, V

=3.3V, unless otherwise noted.

OUT

V

EN

2V/div

V

OUT

1V/div

VEN

2V/div

V

2A/div

VSW

5V/div

IL

Time 10ms/div

OUT

1V/div

2A/div

V

SW

5V/div

I

L

Time 10ms/div

(VIN=12V,V

V

OUT

2V/div

I

L

2A/div

VSW

5V/div

Figure 12. Enable Turn Off Figure 13. Enable Turn On

=3.3V, I

OUT

Time 200µs/div

=3A, with Resister load) (VIN=12V,V

OUT

V

2V/div

2A/div

5V/div

OUT

V

I

SW

=3.3V, I

OUT

L

=3A, with Resistance Load)

OUT

Time 400µs/div

Figure 14. Short Circuit Protection Figure 15. Short Circuit Recovery

=12V, V

(V

IN

OUT

=3.3V, I

=3A) (VIN=12V, V

OUT

OUT

=3.3V, I

OUT

=3A)

Mar. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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Preliminary Datasheet

380kHz, 3A Asynchronous DC - DC Buck Converter AP3203

Typical Application

Figure 8. Typical Application of AP3203

Mar. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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Preliminary Datasheet

380kHz, 3A Asynchronous DC - DC Buck Converter AP3203

Mechanical Dimensions

PSOP-8 Unit: mm(inch)

3.202(0.126)

3.402(0.134)

Mar. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited

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BCD Semiconductor Manufacturing Limited

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