Diodes AP65402 User Manual

A

LIGHT LOAD IMPROVED 4A 500KHZ SYNCH DC/DC BUCK CONVERTER

Description

The AP65402 is a 500kHz switching frequency external compensated

synchronous DC/DC buck converter. It has integrated low R

and low side MOSFETs.

The AP65402 enables continues load current of up to 4A with

efficiency as high as 96%.

The AP65402 implements an automatic custom light load efficiency

improvement algorithm.

The AP65402 features current mode control operation, which enables

fast transient response times and easy loop stabilization.

The AP65402 simplifies board layout and reduces space

requirements with its high level of integration and minimal need for

external components, making it ideal for distributed power

architectures.

The AP65402 is available in a standard Green SO-8EP package and

is RoHS compliant.

DSON

high

Features

Pin Assignments

Applications

P65402

• VIN 4.75V to 17V

• 4A Continuous Output Current, 7A Peak

• Efficiency Up to 96%

• Automated Light Load improvement

• V

• 500kHz Switching Frequency

• External Programmable Soft-Start

• Enable Pin

• OCP with Hiccup and Thermal Protection

• Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)

• Halogen and Antimony Free. “Green” Device (Note 3)

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 for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free.

Adjustable to 0.8 to 12V

OUT

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.

• Gaming Consoles

• Flat Screen TV sets and Monitors

• Set Top Boxes

• Distributed power systems

• Home Audio

• Consumer electronics

• Network Systems

• FPGA, DSP and ASIC Supplies

• Green Electronics

Typical Applications Circuit

AP65402

Document number: DS37107 Rev. 1 - 2

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Figure 1. Typical Application Circuit

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Pin Descriptions

Pin

Name

BS 1

SW 3

GND 4 Ground

FB 5

COMP 6

EN 7

SS 8

EP EP Exposed Pad is connected to ground.

Pin Number Function

High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET a

0.01µF or greater capacitor from SW to BS to power the high side switch.

IN 2

Power Input. IN supplies the power to the IC, as well as the step-down converter switches. Drive IN
with a 4.75V to 17V power source. Bypass IN to GND with a suitably large capacitor to eliminate noise
on the input to the IC. See Input Capacitor.

Power Switching Output. SW is the switching node that supplies power to the output. Connect the
output LC filter from SW to the output load. Note that a capacitor is required from SW to BS to power
the high-side switch.

Feedback Input. FB senses the output voltage and regulates it. Drive FB with a resistive voltage
divider connected to it from the output voltage. The feedback threshold is 0.800V. See Setting the
Output Voltage.

Compensation Node. COMP is used to compensate the regulation control loop. Connect a series RC
network from COMP to GND. In some cases, an additional capacitor from COMP to GND is required.
See Compensation Components.

Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the
regulator; low to turn it off. Attach to IN with a 100k pull up resistor for automatic startup.

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 13ms. To disable the soft-start
feature, leave SS floating.

Functional Block Diagram

P65402

AP65402

Document number: DS37107 Rev. 1 - 2

Figure 2. Functional Block Diagram

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P65402

Absolute Maximum Ratings (Note 4) (@T

Symbol Parameter Rating Unit

VIN

VSW

VBS

VFB

VEN

V

COMP

TST

TJ

TL

ESD Susceptibility (Note 5)

HBM Human Body Model 1.5 kV

MM Machine Model 150 V

Notes: 4. Stresses greater than the 'Absolute Maximum Ratings' specified above may cause permanent damage to the device. These are stress ratings only;
functional operation of the device at these or any other conditions exceeding those indicated in this specification is not implied. Device reliability may
be affected by exposure to absolute maximum rating conditions for extended periods of time.

5. Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when
handling and transporting these devices.

Supply Voltage

Switch Node Voltage

Bootstrap Voltage

Feedback Voltage -0.3V to +6.0 V

Enable/UVLO Voltage -0.3V to +6.0 V

Comp Voltage -0.3V to +6.0 V

Storage Temperature -65 to +150 °C

Junction Temperature +160 °C

Lead Temperature +260 °C

= +25°C, unless otherwise specified.)

A

-0.3 to 20

-1.0 to V

V

-0.3 to VSW +6.0

SW

IN

+0.3

V

V

V

Thermal Resistance

Symbol Parameter Rating Unit

JA

JC

Note: 6. Test condition: SO-8EP: Device mounted on FR-4 substrate (2s2p) 2"x2" PCB, with 2oz copper trace thickness and minimum recommended pad on top

layer and thermal vias to bottom layer ground plane.

Recommended Operating Conditions (Note 7) (@T

Symbol Parameter Min Max Unit

VIN

TA

Note: 7. The device function is not guaranteed outside of the recommended operating conditions.

Junction to Ambient SO-8EP (Note 6) 39.2 °C/W

Junction to Case SO-8EP (Note 6) 5.6 °C/W

= +25°C, unless otherwise specified.)

A

Supply Voltage

Operating Ambient Temperature Range

4.75

-40

17.0 V

+85 °C

AP65402

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P65402

Electrical Characteristics (@T

Symbol Parameter Test Conditions Min Typ Max Unit

I

SHDN

IQ

R

DS(ON)1

R

DS(ON)2

I

LIMIT

I

LIMIT

— High-Side Switch Leakage Current

AVEA

GEA Error Amplifier Transconductance

GCS

FSW

FFB

D

MAX

TON

VFB

— Feedback Overvoltage Threshold — — 1.0 — V

V

EN_RISING

— EN Lockout Threshold Voltage — 2.2 2.5 2.7 V

— EN Lockout Hysteresis — — 220 — mV

INUV

VTH

INUV

HYS

—

—

TSD

Note: 8. Guaranteed by design

AP65402

Document number: DS37107 Rev. 1 - 2

Shutdown Supply Current

Supply Current (Quiescent)

High-Side Switch On-Resistance (Note 8) —

Low-Side Switch On-Resistance (Note 8) —

HS Current Limit Minimum duty cycle

LS Current Limit From Drain to Source

Error Amplifier Voltage Gain
(Note8)

COMP to Current Sense
Transconductance

Oscillator Frequency

Fold-back Frequency

Maximum Duty Cycle

Minimum On Time —

Feedback Voltage

EN Rising Threshold — 0.7 0.8 1.2 V

V

Under Voltage Threshold Rising

IN

VIN Under Voltage Threshold Hysteresis

Soft-Start Current

Soft-Start Period

Thermal Shutdown (Note 8) —

= +25°C, VIN = 12V, unless otherwise specified.)

A

VEN = 0V

VEN = 2.0V, VFB = 1.0V

V

= 0V, VSW = 0V, V

EN

SW

=12V

— — 800 — V/V

I

= ±10µA

C

— — 2.8 — A/V

V

= 0.75V

FB

V

= 0V

FB

VFB = 800mV

TA = -40°C to +85°C

— 3.80 4.05 4.40 V

—

V

= 0V

SS

C

= 0.1µF

SS

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—

—

—

—

—

—

—

0.3 3.0 µA

0.3 1.5 mA

80

32

7

0.9

—

—

—

—

m

m

A

A

0 10 A

— 1000 — µA/V

440 500 560 kHz

—

—

—

—

—

—

—

—

0.30

90

160

800

250

6

13

160

—

—

—

—

—

—

—

—

fSW

%

ns

mV

mV

A

ms

°C

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Typical Performance Characteristics (@T

= +25°C, VIN = 12V, V

A

= 3.3V, unless otherwise specified.)

OUT

P65402

AP65402

Document number: DS37107 Rev. 1 - 2

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