Diodes AP3502E User Manual

340kHz, 2A Synchronous DC-DC Buck Converter AP3502E

Data Sheet

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.

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

Dec. 2012 Rev. 1. 5 BCD Semiconductor Manufacturing Limited

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Data Sheet

340kHz, 2A Synchronous DC-DC Buck Converter AP3502E

Pin Configuration

M Package (SOIC-8)

BS

1

IN

SW

2

3

4

GND

Figure 2. Pin Configuration of AP3502E (Top View)

8

7

6

5

SS

EN

COMP

FB

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

and SW pin. The voltage across the bootstrap capacitor drives the internal high-side power MOSFET

IN

SW

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

GND 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

FB

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

COMP

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

EN

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

SS

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

Dec. 2012 Rev. 1. 5 BCD Semiconductor Manufacturing Limited

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Data Sheet

340kHz, 2A Synchronous DC-DC Buck Converter AP3502E

Functional Block Diagram

Figure 3. Functional Block Diagram of AP3502E

Ordering Information

AP3502E -

Circuit Type

Package

SOIC-8

Temperature

M: SOIC-8

Range

-40 to 85°C

Part Number Marking ID Packing Type

AP3502EM-G1 3502EM-G1 Tube

AP3502EMTR-G1 3502EM-G1 Tape & Reel

BCD Semiconductor's Pb-free products, as designated with "G1" suffix in the part number, are RoHS compliant and green.

G1: Green

TR: Tape & Reel Blank: Tube

Dec. 2012 Rev. 1. 5 BCD Semiconductor Manufacturing Limited

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Data Sheet

340kHz, 2A Synchronous DC-DC Buck Converter AP3502E

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 (Human Body Model) V

ESD (Machine Model) VMM 200 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.

-0.3 to 6 V

COMP

θ

JA

-65 to 150 ºC

STG

260 ºC

LEAD

2000 V

HBM

105 ºC/W

Recommended Operating Conditions

Parameter Symbol Min Max Unit

Input Voltage VIN 4.5 18 V

Operating Ambient Temperature TA -40 85 ºC

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Data Sheet

340kHz, 2A Synchronous DC-DC Buck Converter AP3502E

Electrical Characteristics

TA=25ºC, VIN=VEN=12V, V

Parameter Symbol Conditions Min Typ Max Unit

SUPPLY VOLTAGE (IN PIN)

Input Voltage VIN 4.5 18 V

Quiescent Current IQ VFB=1V, VEN=3V 1.2 1.4 mA

Shutdown Supply Current I

UNDER VOLTAGE LOCKOUT

Input UVLO Threshold V

Input UVLO Hysteresis V

ENABLE (EN PIN)

EN Shutdown Threshold Voltage 1.1 1.5 2 V

EN1Shutdown1Threshold1Vo l t a g e 1Hysteresis (Note 3)

EN Lockout Threshold Voltage 2.2 2.5 2.7 V

EN Lockout Hysteresis 210 mV

VOLTAGE REFERENCE (FB PIN)

Feedback Voltage VFB 0.907 0.925 0.943 V

Feedback Over Voltage Threshold V

Feedback Bias Current IFB VFB=1V -0.1 0.1

MOSFET

High-side Switch On-resistance (Note 2) R

Low-side Switch On-resistance (Note 2) R

CURRENT LIMIT

High-side Switch Leakage Current I

High-side Switch Current Limit I

Low-side Switch Current Limit I

SWITCHING REGULATOR

Oscillator Frequency f

Short Circuit Oscillator Frequency f

Max. Duty Cycle D

Min. Duty Cycle D

ERROR AMPLIFIER

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

Error Amplifier Transconductance GEA 800

COMP to Current Sense Transconductance GCS 3.5 A/V

THERMAL SHUTDOWN

Thermal Shutdown (Note 3) T

Thermal Shutdown Hysteresis (Note 3) T

SOFT START (SS PIN)

Soft-start Time (Note 3) tSS

Soft-start Current 5

Note 2: R

DSON

=

Note 3: Not tested, guaranteed by design.

=3.3V, unless otherwise specified.

OUT

VEN=0V 0.1 10

SHDN

UVLO

200 mV

HYS

350 mV

FBOV

DSONHISW

DSONLISW

LEAKH

LIMH

LIML

280 340 400 kHz

OSC1

90 kHz

OSC2

VFB=0.85V 90 %

MAX

VFB=1V 0 %

MIN

OTSD

30 ºC

HYS

V-V

SW2SW1

I-I

μA

VIN Rising 3.65 4.00 4.25 V

1.1 V

μA

=0.2A/0.7A

=-0.2A/-0.7A

VIN=18V,VEN=VSW=0V 0.1 10

2.7 3.5 A

Drain to Source 0 mA

160 ºC

C5=0.1μF

100

15 ms

mΩ

μA

μA/V

μA

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Data Sheet

340kHz, 2A Synchronous DC-DC Buck Converter AP3502E

Typical Performance Characteristics

TA=25ºC, VIN=12V, V

100

90

80

70

60

50

40

Efficiency (%)

30

20

10

0.01 0.1 1 10

Figure 4. Efficiency vs. Load Current

0.94

0.93

0.92

Feedback Voltage (V)

0.91

0.90

-50 -25 0 25 50 75 100 12 5 150

Figure 6. Feedback Voltage vs. Temperature

Dec. 2012 Rev. 1. 5 BCD Semiconductor Manufacturing Limited

=3.3V, unless otherwise noted.

OUT

V

Load Current (A)

=3.3V,L=10μH T

OUT

V

=5V

IN

V

=12V

IN

=25oC

A

Figure 5. Quiescent Current vs. Temperature

Temperature (oC)

1.4

1.3

1.2

1.1

Quiescent Current (mA)

1.0

0.9

-50 -25 0 25 50 75 100 125 150

3.6

3.5

3.4

3.3

3.2

Output Voltage (V)

3.1

3.0

0.0 0.4 0.8 1.2 1.6 2.0 2.4

Temperature (oC)

Load Current (A)

Figure 7. Output Voltage vs. Load Current

6

Data Sheet

340kHz, 2A Synchronous DC-DC Buck Converter AP3502E

Typical Performance Characteristics (Continued)

TA=25ºC, VIN=12V, V

3.6

3.5

3.4

3.3

4 8 12 16 20

Output Voltage (V)

3.2

3.1

3.0

Figure 8. Output Voltage vs. Figure 9. Maximum Load Current vs.

=3.3V, unless otherwise noted.

OUT

Input Voltage (V)

4.0

3.6

3.2

2.8

2.4

2.0

Max Load Current (A)

1.6

1.2 4 8 12 16 20

V

OUT

Input Voltage (V)

=3.3V,L=10μH

Input Voltage Input Voltage

(AC)

V

IN

500mV/div

(AC)

V

OUT

20mV/div

I

L

1A/div

V

SW

10V/div

Dec. 2012 Rev. 1. 5 BCD Semiconductor Manufacturing Limited

Figure 10. Output Ripple (I

=2A) Figure 11. Load Transient (I

OUT

(AC)

V

OUT

100mV/div

I

OUT

1A/div

7

Time 400μs/div Time 2μs/div

=1A to 2A)

OUT

Data Sheet

340kHz, 2A Synchronous DC-DC Buck Converter AP3502E

Typical Performance Characteristics (Continued)

=25ºC, VIN=12V, V

T

A

=3.3V, unless otherwise noted.

OUT

V

EN

2V/div

V

SS

2V/div

V

OUT

2V/div

I

L

1A/div

2V/div

V

2V/div

V

OUT

2V/div

1A/div

EN

SS

I

L

Time 4ms/div

Time 200μs/div

Figure 12. Enable Turn-on Characteristic Figure 13. Enable Turn-off Characteristic (VIN=12V, VEN=3.3V, V

OUT

=3.3V, I

=2A) (VIN=12V, VEN=3.3V, V

OUT

=3.3V, I

OUT

=2A)

V

OUT

2V/div

V

SW

10V/div

V

SS

1V/div

I

L

2A/div

Time 40ms/div

V

OUT

2V/div

V

SW

10V/div

V

1V/div

2A/div

SS

I

L

Time 40ms/div

Figure 14. Short Circuit Protection (I

=2A) Figure 15. Short Circuit Recovery (I

OUT

=2A)

OUT

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Data Sheet

340kHz, 2A Synchronous DC-DC Buck Converter AP3502E

Typical Application

Input Voltage=12V

Output Voltage=3.3V

C21

22μF/25V

L 10μH

C22

22μF/25V

C4

10nF

D1

Optional

R4

100k

1

BS

2

IN

3

SW

4

GND

COMP

AP3502E

SS

EN

FB

8

C5

R1

26.1k

0.1μF

C3

4.7nF

R2 10k

C6

Optional

R3

13k

7

6

5

C11 10μF/25V

Figure 16. Typical Application of AP3502E

Dec. 2012 Rev. 1. 5 BCD Semiconductor Manufacturing Limited

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Data Sheet

340kHz, 2A Synchronous DC-DC Buck Converter AP3502E

Mechanical Dimensions

SOIC-8 Unit: mm(inch)

4.700(0.185)

5.100(0.201)

7

°

7

°

1.270(0.050)

TYP

0.100(0.004)

0.300(0.012)

1.350(0.053)

1.750(0.069)

0.675(0.027)

0.725(0.029)

D

2

D

1

:

0

0.320(0.013)

5.800(0.228)

6.200(0.244)

0.800(0.031)

°

8

°

8

0.200(0.008)

0

°

8

°

1° 5°

0.450(0.017)

0.800(0.031)

)

6

0

.

0

(

0

5

1

.

0

R

1.000(0.039)

0.330(0.013)

0.510(0.020)

R0.150(0.006)

3.800(0.150)

4.000(0.157)

0.190(0.007)

0.250(0.010)

0.900(0.035)

Note: Eject hole, oriented hole and mold mark is optional.

Dec. 2012 Rev. 1. 5 BCD Semiconductor Manufacturing Limited

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