Diodes AP3436A User Manual

AP3436/A

Document number: DS37212 Rev. 2 - 2

1 of 15

www.diodes.com

April 2014

© Diodes Incorporated

AP3436/A

A Product Line of

Diodes Incorporated

Description

The AP3436/A is a step-down DC-DC converter with integrated
power stage capable of driving up to 3A continuous output current. It
integrates 2 N-channel power MOSFETs with low on-resistance.
Current mode control provides fast transient response and cycle-by­cycle current limit.

For AP3436, the regulator adopts current-mode in forced pulse-width
modulation (PWM) mode with 1.25MHz switching frequency
internally, which allows small-sized components, such as capacitors
and inductors. This feature greatly simplifies the design of switch­mode power supplies. Under PWM mode, the device remains at the
fixed PWM operation (typical at 1.25MHz), regardless of if the load
current is high or low.

For AP3436A, the regulator operates in either fixed PWM mode or a
pulse-skipping modulation (PSM) mode depending on the different
load conditions. The device can operate at typical 1.25MHz fixed
switching frequency under heavy load condition. At light load, the
regulator enters a PSM mode to minimize the switching loss by
reducing the switching frequency.

The AP3436/A provides EN function. Pulling this pin high statically
enables the device while pulling the pin low statically for longer than
10μs will shut it down.

Under Voltage Lockout is internally set at 2.75V for VCC detection.
The output voltage startup ramp is controlled by the soft start. An
open drain power good signal indicates the output is within 75% to
125% of its nominal voltage.

The AP3436/A is available in U-DFN3030-10 package.

Applications

 Desktop & Notebook
 Low Voltage, High Density Power System
 Consumer Application Such as Set Top Box, LCD Display and

CPE Equipment

Pin Assignments

(Top View)

U-DFN3030-10

Features

 Analog Power Input VCC Range: 3.0V to 5.5V
 Power Input VIN Range: 1.3V to 5.5V
 0.6V Reference Voltage with ±1.5% Precision
 2 MOSFETs (Typ 50mΩ) for High Efficiency at 3A Loads
 High Efficiency: Up to 95%
 Output Current: 3A
 Current Mode Control
 Built-in Soft Start Function
 UV and OV Power Good Output
 Built-in UV and OV Protection Function
 Built-in Over Current Protection
 Built-in Thermal Shutdown Function
 Thermally Enhanced 3mm×3mm DFN Package

 Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
 Halogen and Antimony Free. “Green” Device (Note 3)

FB

GND

VCC

VIN

GND

SW

SW

BOOT

PGOOD

EN

Pin 1 Mark

1

2

3

4

5 6

7

8

9

10

11

EP

3A, 1.25MHz High Performance Synchronous Buck Converter

Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.

2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.

3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.

AP3436/A

Document number: DS37212 Rev. 2 - 2

2 of 15

www.diodes.com

April 2014

© Diodes Incorporated

AP3436/A

A Product Line of

Diodes Incorporated

PGOOD

EP

EN

VCC

FB

GND

GND

SW

SW

BOOT

VIN

R

PG

V

CC

C

VCC

V

OUT

C

BOOT

L1

C

OUT

R

FB2

R

FB1

V

IN

C

IN

9

10

2

1

6
7
4

5

11

8

3

AP3436/A

Component

Value

Unit

Component

Value

Unit

C

VCC

1

µF

CIN

44

µF

RPG

10

kΩ

C

BOOT

0.1

µF

R

FB2

TBD

kΩ

L1

1.5

µH

R

FB1

TBD

kΩ

C

OUT

88

µF

Typical Applications Circuit

Note 4: When using a single power supply for VCC and VIN, a 4.7Ω resistor should be placed between them for noise isolation.

Table 1. Component Guide

AP3436/A

Document number: DS37212 Rev. 2 - 2

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April 2014

© Diodes Incorporated

AP3436/A

A Product Line of

Diodes Incorporated

Pin Number

Pin Name

Function

1

FB

Voltage Feedback Input. Connect to V

OUT

through a voltage divider to set

the output voltage

2

VCC

Analog Power Input 3 VIN

Power Input

4, 5

GND

Ground. Must be Connected to GND on PCB

6, 7

SW

Power Switch Output

8

BOOT

High Side Switch Driver Supply

9

PGOOD

Open Drain Power Good Output

10

EN

Enable

11

Exposed Pad

Thermal Connection to the PCB. Must be connected to GND on PCB

75%

Logic

125%

EA

Voltage

Reference

Soft Start

EN

Shutdown

Logic

Thermal

Shutdown

UVLO

Boot

Charge

Boot

UVLO

Logic and

PWM Latch

PWM

Slope

Compensation

Oscillator

Current Limit and

Short Protection

Current

Sense

FB

1

2

VCC

9

10

PGOOD

EN

GND

GND

SW

BOOT

3

VIN

8

6,7

4,5

4,5

+

Pin Descriptions

Functional Block Diagram

AP3436/A

Document number: DS37212 Rev. 2 - 2

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April 2014

© Diodes Incorporated

AP3436/A

A Product Line of

Diodes Incorporated

Symbol

Parameter

Rating

Unit

V

CC, VIN

VCC, VIN Pin Voltage

-0.3 to 6

V

VEN

EN Pin Voltage

-0.3 to 6

V

VSW

SW Pin Voltage

-0.3 to VIN+0.3

V

V

SW_TRANSIENT

SW Pin Transient Voltage (<50ns)

-5 to VIN+5

V

VFB

FB Pin Voltage

-0.3 to 6

V

V

PGD

PGOOD Pin Voltage

-0.3 to 6

V

V

BOOT_SW

BOOT to SW Voltage

0 to 6

V

θ

JA

Thermal Resistance (Junction to Ambient, Simulation)

33

ºC/W

θ

JC

Thermal Resistance (Junction to Case)

3

ºC/W

TJ

Operating Junction Temperature

-40 to +150

ºC

T

STG

Storage Temperature

-65 to +150

ºC

T

LEAD

Lead Temperature (Soldering, 10sec)

+260

ºC

V

HBM

ESD (Human Body Model)

2000

V

VMM

ESD (Machine Model)

200

V

Symbol

Parameter

Min

Max

Unit

VCC

Analog Input Voltage

3.0

5.5

V

VIN

Power Input Voltage

1.3

5.5

V

I

OUT(MAX)

Maximum Output Current

3 – A

V

OUT

Output Voltage

0.8

VIN V TA

Operating Ambient Temperature

-40

+85

ºC

Absolute Maximum Ratings (Note 5)

Note 5: 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 Operati ng Conditions” is not implied.
Exposure to “Absolute Maximum Ratings” for extended periods may affect device reliability.

Recommended Operating Conditions

AP3436/A

Document number: DS37212 Rev. 2 - 2

5 of 15

www.diodes.com

April 2014

© Diodes Incorporated

AP3436/A

A Product Line of

Diodes Incorporated

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

SUPPLY VOLTAGE (VCC, VIN PIN)

VCC

Analog Power Input Voltage

–

3.0 – 5.5

V

VIN

Power Input Voltage

–

1.3 – 5.5

V

IQ

Quiescent Current

V

FB

= 1.5V, V

CC

= 5V,

V

IN

= 5V

–

400 – µA

I

SHDN

Shutdown Supply Current

V

EN

= 0V,

3.0V ≤ V

CC

≤ 5.5V,

1.3V ≤ V

IN

≤ 5.5V

– – 1

µA

POWER ON RESET

V

UVLO

Internal Under Voltage Lockout
Threshold for VCC

– – 2.75

2.85

V

V

HYS_VCC

Internal Under Voltage Hysteresis
for VCC

– – 150 – mV

VOLTAGE REFERENCE (FB PIN)

VFB

Voltage Reference

3.0V ≤ V

CC

≤ 5.5V

0.591

0.600

0.609

V

INTERNAL PWM FREQUENCY

f

PWM Frequency

3.0V ≤ V

CC

≤ 5.5V

1.0

1.25

1.5

MHz

MOSFET SPEC

R

ON_H

High Side Switch On-resistance
V

BOOT_SW

= 5.0V

–

50

100

mΩ

V

BOOT_SW

= 3.0V

–

70

140

mΩ

R

ON_L

Low Side Switch On-resistance
V

CC

= 5.0V

–

50

100

mΩ

V

CC

= 3.0V

–

70

140

mΩ

CURRENT LIMIT

I

LIMIT

Current Limit Threshold

–

4.8

7.6 – A

THERMAL SHUTDOWN

T

TSD

Thermal Shutdown

– – +160 – °C

–

Hysteresis

– – +20 – °C

BOOT SPEC (BOOT PIN)

R

BOOT

BOOT Charge Resistor

V

CC

= 5.0V

–

16 – Ω

–

BOOT to SW UVLO

V

CC

= 3.0V

–

2.2 – V

SOFT START

tSS

Soft Start Time

–

0.8 – 2

ms

Electrical Characteristics (V

CC

= 5V, V

= 5V, TA = +25°C, unless otherwise specified.)

IN