Diodes AP5727 User Manual

Description

The AP5727 is a high efficiency boost converter in a
compact SOT25 that provides the bias voltages for OLED
Sub Display and TFT-LCD (Liquid Crystal Display).
A high 1.2MHz switching frequency and internal
compensation minimizes external part count, PCB area and
cost. Integrated soft start reduces inrush current.
The AP5727 has a 1.25V feedback voltage making it
compatible with industry standard boost converters used to
bias LCD panels.

BIAS POWER SUPPLY FOR OLED

SUB DISPLAY AND TFT-LED

Pin Assignments

1

SW

2

GND

3

FB

( Top View )

SOT25

AP5727

IN

V

5

7

4

EN

Features

• 30V High Output Voltage

• Fast 1.2MHz Switching Frequency

NEW PRODUCT

• Current limit and UVLO Protections

• Internal Thermal Shutdown

• Maximum 1µA Shutdown Current

• Integrated Soft-start Function

• SOT25: Available in “Green” Molding Compound

(No Br, Sb)

• Lead Free Finish/RoHS Compliant (Note 1)

Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at http://www.diodes.com/products/lead_free.html.

Applications

• Small size TFT-LCD Bias power supply.

• OLED bias supply for a clamshell handset sub display

• RF amplifier bias voltages

Typical Application Circuit

L1

V

IN

22uH

C

IN

4.7uF

V

IN

SW

D1

R1

C

OUT

10uF

V

OUT

AP5727

Document number: DS31887 Rev. 2 - 2

AP5727

EN

FB

GND

Figure 1. Typical Application Circuit

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Functional Block Diagram

FB

3

V

1.25V

Regulator On/Off Control Input. A high input at EN turns on the converter, and a low input turns it off. When not
used, connect EN to the input source for automatic startup. The EN pin cannot be left floating.

NEW PRODUCT

Pin Descriptions

Name Description

SW Switch Pin. Connect inductor/diode here. Minimize trace area at this pin to reduce EMI.

GND GND pin

FB Feedback Pin. Reference voltage is 1.25V.
EN
VIN Input Supply Pin. Must be locally decoupled - 4.7μF recommended to reduce input noise.

V

EN

5

IN

4

REF

Shutdown

AP5727

BIAS POWER SUPPLY FOR OLED

SUB DISPLAY AND TFT-LED

1

2

SW

Q1

GND

Comparator

-

A2

+

R

A1

-

+

C

C

C

R

Q

S

Driver

+

Σ

-

RAMP

Generator

1.2MHz

Oscillator

Figure 2. Block Diagram

AP5727

Document number: DS31887 Rev. 2 - 2

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AP5727

BIAS POWER SUPPLY FOR OLED

SUB DISPLAY AND TFT-LED

Absolute Maximum Ratings (T

Symbol Parameter Rating Unit

VIN VIN Pin Voltage -0.3~7 V

VSW SW Voltage -0.3~32 V

VFB Feedback Pin Voltage -0.3~7 V
EN EN -0.3~7 V

T

Maximum Junction Temperature 150 °C

J(MAX)

T

Lead Temperature 300 °C

LEAD

TST Storage Temperature Range -65 to +150 °C

Caution: The absolute maximum ratings are rated values exceeding which the product could suffer physical damage. These values must therefore not be

exceeded under any condition.

Recommended Operating Conditions

Symbol Parameter Min Max Unit

VIN Input Voltage 2.7 5.5 V

TJ Operating Junction Temperature -40 125 °C

NEW PRODUCT

TA Operating Ambient Temperature -40 85 °C

Electrical Characteristics (V

Symbol Parameter Conditions Min. Typ. Max. Unit

System Supply Input

VIN Operating Input Voltage 2.7 - 5.5 V

UVLO Under Voltage Lockout - 2.2 2.4 V

Under Voltage Lockout Hysteretic - 85 - mV

IQ Quiescent Current FB=1.3V, No Switching - 500 - μA

ISD Shutdown Current VEN < 0.4V - 0.1 1 μA

Oscillator

F

Operation Frequency 1 1.2 1.4 MHz

OSC

Dmax Maximum Duty Cycle 86 90 - %

Reference Voltage

VFB Feedback Voltage 1.225 1.25 1.275 V

IFB FB Pin Bias Current 10 45 100 nA

MOSFET

R

On Resistance of MOSFET - 0.95 1.2 Ω

DS(on)

I

Switching Current Limit Normal Operati on - 750 - mA

OCP

Control and Protection

EN Voltage High ON 1.5 - - V
EN Voltage Low OFF - - 0.4 V

IEN EN Pin Pull Low Current - 4 6 μA

Thermal Resistance Junction-to-

θ

JA

Ambient
Thermal Resistance Junction-to-

θ

JC

Case

Notes: 2. Test condition for SOT25: Device mounted on FR-4 substrate, single-layer PC board, 2oz copper, with minimum recommended pad layout

AP5727

Document number: DS31887 Rev. 2 - 2

= 25°C)

A

= 3.6V, TA = 25°C, unless otherwise specified)

IN

SOT25 (Note 2) 162

SOT25 (Note 2) 36

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