Diodes AP3605 User Manual

Data Sheet

4-Channel Charge Pump LED Driver with Current Balancing and Wide Range PWM Dimming AP3605

General Description

The AP3605 is a step-up DC/DC converter based on

1.5x charge pump current source, it is specially
designed for LED supplies in backlight display.

The AP3605 can provide constant current up to 20mA
for each LED, which is programmed by an external
resistor, so it has a total capability to provide 80mA for
4 LEDs. The chip has a good performance of LED
current matching and allows PWM brightness dim­ming control. Additionally, high switching frequency
up to 1MHz enables the use of two small external
flying capacitors. Internal soft-start circuitry prevents
excessive inrush current during start-up.

The AP3605 supply voltage range is from 2.7V to

5.5V, ideally suited for applications powered by the Li­ion battery.

The AP3605 is available in a 3mmx3mm QFN-3x3-16
tiny package. Its operating temperature range is -40

o

C.

to 85

o

Features

· Regulated Output Current with ±3% Matching

· Regulated ±10% Output Current Source

· Drive up to 4 LEDs at 20mA Each

· Wide Operating Voltage Range: 2.7V to 5.5V

· High Efficiency up to 93%

· High Operating Frequency: 1MHz

· Built-in Soft-Start to Limit the Inrush Current

· LED Brightness Control through PWM and Ana-

log Signal

· PWM Dimming Frequency up to 50kHz

· Built-in Standby Mode to Get PWM Dimming

Duty Cycle Control Linearity

· Built-in OTSD (Over Temperature Shutdown)
Function to Protect the Device from Burn Out

Applications

· Mobile Phone

C

· MP3, MP4

· White LED Backlight in Mobile Phone, PDA

QFN-3x3-16

Figure 1. Package Type of AP3605

Jan. 2013 Rev. 1. 8 BCD Semiconductor Manufacturing Limited

1

Data Sheet

E P

5678

1

2

3

49

12

Pin 1 Mark

11

10

13

141516

4-Channel Charge Pump LED Driver with Current Balancing and Wide Range PWM Dimming AP3605

Pin Configuration

FN Package

(

QFN-3x3-16

)

C1

D1D2

V

IN2

EN

ISET

AGND

C1+

-

C2+

V

OUT2

Exposed PAD, Connected to AGND

D4

V

OUT1

PGND

C2-

V

D3

IN1

Note: Pin 2 should be connected with Pin 8 and Pin 5 should be connected with Pin 13 on PCB board.

Figure 2. Pin Configuration of AP3605 (Top View)

Pin Description

Pin Number Pin Name Function

1, 16, 15, 14 D4 to D1 Current Source Output. Connect the anode of the white LEDs to these outputs

2, 8

3 PGND Power Ground. Connect this pin with power ground plane

4C2-

5, 13 V

6C1-

7C2+

9C1+

10 AGND

11 ISET

12 EN

V

OUT1, VOUT2

IN1, VIN2

Output Pin 1 and 2, must be connected together. The output capacitor should be placed
closely to these pins

Flying Capacitor 2 Negative Terminal. The flying capacitor 2 should be connected as close
to this pin as possible

Supply Voltage Input 1 and 2, must be connected together

Flying Capacitor 1 Negative Terminal. The flying capacitor 1 should be connected as close
to this pin as possible

Flying Capacitor 2 Positive Terminal. The flying capacitor 2 should be connected as close to
this pin as possible

Flying Capacitor 1 Positive Terminal. The flying capacitor 1 should be connected as close to
this pin as possible

Analog Ground. Connect this pin with control signal ground plane. PGND, AGND and the
exposed PAD should be connected together

Current Source Set Pin. Connect a resistor between this pin and GND to set the maximum
LED current

Enable Control Input. Logic high enables the IC; while logic low forces the device into shut­down mode to reduce the supply current to less than 1μA. Add a PWM signal to this pin to
achieve brightness control

Jan. 2013 Rev. 1. 8 BCD Semiconductor Manufacturing Limited

2

Data Sheet

5

15

11

1

Voltage

Reference

6

1.5x Charge Pump
4-Channel

Current

Source

47 9

16

14

3

12

10

13

8

2

LDO

Soft

Start

1MHz

OSC

Standby

OTSD

+

_

Error
AMP

4-Channel Charge Pump LED Driver with Current Balancing and Wide Range PWM Dimming AP3605

Functional Block Diagram

C2- C2+ C1+

C1-

V

OUT2

V

OUT1

D1

V

IN1

D2

D3

D4

ISET

V

IN2

EN

PGND

Figure 3. Functional Block Diagram of AP3605

AGND

Ordering Information

AP3605 -

Circuit Type

Package

FN: QFN-3x3-16

Package Temperature Range Part Number Marking ID Packing Type

QFN-3x3-16

Note 1: AP3605FNTR-E1 is a green product.

-40 to 85

o

C

AP3605FNTR-E1 (Note 1) F1A Tape & Reel

Jan. 2013 Rev. 1. 8 BCD Semiconductor Manufacturing Limited

E1: RoHS

TR: Tape and Reel

3

Data Sheet

4-Channel Charge Pump LED Driver with Current Balancing and Wide Range PWM Dimming AP3605

Absolute Maximum Ratings (Note 2)

Parameter Symbol Value Unit

Input Voltage V

EN Pin Voltage V

V

Pin Voltage V

OUT1

V

Pin Voltage V

OUT2

ISET Pin Voltage V

Output Current at V

Pin I

OUT2

OUT2

Thermal Resistance (Junction to Ambient, no Heat sink) R

Operating Junction Temperature T

Storage Temperature Range T

Lead Temperature (Soldering, 10sec) T

LEAD

IN

EN

OUT1

OUT2

ISET

θJA

J

STG

-0.3 to 6 V

-0.3 to 6 V

-0.3 to 6 V

-0.3 to 6 V

-0.3 to 6 V

150 mA

60

150

-65 to 150

260

o

C/W

o

C

o

C

o

C

ESD (Human Body Model) 2000 V

Note 2: 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

Operating Temperature T

Current Source Set Resistor R

V

ISET

IN

A

Jan. 2013 Rev. 1. 8 BCD Semiconductor Manufacturing Limited

4

2.7 5.5 V

-40 85

o

1.44 kΩ

C