Richtek RT9284A-15PJ6, RT9284A-15PJ6E, RT9284A-20GJ6E, RT9284A-20PJ6, RT9284A-20PJ6E Schematic [ru]

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RT9284A/B

Tiny Package, High Performance, Constant Current Switching Regulator for White LED

General Description

The RT9284A/B is a compact, high efficient and high integration LED driver. Internal 22V MOSFET can support 2 to 5 White LEDs for backlighting and camera flashing.

Highly integration and internal compensation network minimizes as 5 external component counts. Optimized operation frequency can meet the requirement of small LC filters value and low operation current with high efficiency. Internal soft start function can reduce the inrush current. Tiny package type of TSOT-23-5 and TSOT-23-6 packages provide the best solution for PCB space saving and total BOM cost.

Features

zVIN Operating Range : 2.7V to 5.5V

zMaximum Output Voltage up to 20V

zDimming with Zero-inrush and Wide Frequency Range of 100 to 100kHz

zOver Voltage Protection

zOutput Current up to 100mA at VOUT : 12V

zZero Shutdown Supply Current

zMinimize the External Component

zSmall LC Filter

zInternal Soft Start

zRoHS Compliant and 100% Lead (Pb)-Free

Ordering Information

RT9284(-)

Package Type

J5 : TSOT-23-5

J6 : TSOT-23-6

Lead Plating System

P : Pb Free

G : Green (Halogen Free and Pb Free)

OVP Voltage 15 : 15V

20 : 20V

FB Voltage

A : 1.235V

B : 0.25V

Note :

Richtek products are :

`RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.

`Suitable for use in SnPb or Pb-free soldering processes.

Marking Information

For marking information, contact our sales representative directly or through a Richtek distributor located in your area.

Applications

zCamera Flash White LED

zMobile Phone, Smart Phone LED Backlight

zPDA LED Backlight

zDigital Still Camera

zCamcorder

Pin Configurations

TOP VIEW

VDD EN

5 4

2 3

LX GND FB

TSOT-23-5

VDD OVP EN

6 5 4

2 3

LX GND FB

TSOT-23-6

DS9284A/B-07 April 2011

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Richtek RT9284A-15PJ6, RT9284A-15PJ6E, RT9284A-20GJ6E, RT9284A-20PJ6, RT9284A-20PJ6E Schematic

RT9284A/B

Typical Application Circuit

 

 

 

L1

 

D1

OVP

 

 

 

 

4.7uH to 22uH

SS0520

15V

 

 

 

 

 

 

 

 

VIN +

C1

 

 

 

 

C2

ILED

2.7V to 5.5V

1uF

 

RT9284

 

1uF/16V

 

 

6

1

 

 

 

 

 

 

 

 

VDD

LX

 

 

Dimming

 

4 EN

OVP 5

 

 

Control

 

2 GND

 

 

 

 

100Hz-100kHz

FB 3

 

 

 

 

 

 

 

 

 

R1

Figure 1. Application for Driving 3 Series WLEDs

 

 

 

 

L1

D1

 

 

OVP

 

 

 

 

 

4.7uH to 22uH

SS0520

 

 

18V

 

 

 

 

 

 

 

 

 

 

 

 

VIN +

C1

 

 

 

 

 

 

C2

ILED

2.7V to 5.5V

1uF

 

RT9284

 

 

R2

1uF/25V

 

 

 

 

 

 

 

 

 

 

 

 

6 VDD

LX

1

 

600k

 

 

Dimming

 

 

4 EN

OVP

5

 

 

 

 

 

Control

 

 

2 GND

 

OVP 15V

 

 

 

 

 

100Hz-100kHz

 

FB 3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R1

 

Figure 2. Application for Driving 4 Series WLEDs

 

 

 

 

 

 

L1

D1

 

OVP

 

 

 

 

 

4.7uH to 22uH

SS0520

20V

 

 

 

 

 

 

 

 

 

 

 

VIN +

C1

 

 

 

 

 

 

C2

ILED

2.7V to 5.5V

1uF

 

RT9284B

 

 

 

1uF/25V

 

 

 

6

 

 

 

 

 

 

 

 

VDD

LX 1

 

 

 

 

 

 

Dimming

 

4 EN

OVP 5

 

 

 

 

 

 

Control

 

2 GND

 

 

 

 

 

 

 

100Hz-100kHz

FB 3

VFB = 0.25V

 

 

 

 

 

 

 

 

 

 

 

R1

 

Figure 3. Application for Driving 5 Series WLEDs

 

 

 

 

 

L1

D1

OVP

 

V

 

 

 

 

4.7uH to 22uH

SS0520

15V

 

OUT

VIN +

 

 

 

 

 

 

 

 

12V

C1

 

 

 

 

 

 

R1

C2

 

2.7V to 5.5V

1uF

 

RT9284A

 

 

 

1uF/16V

 

6

 

 

 

130k

 

 

 

 

VDD

LX 1

 

 

 

 

 

 

 

 

4 EN

OVP 5

 

 

 

 

 

 

 

 

2 GND

FB 3

 

 

 

VFB = 1.235V

 

 

 

 

 

 

 

 

 

R2

 

 

 

 

 

 

 

 

 

 

15k

 

 

Figure 4. Application for Constant Output Voltage

 

 

www.richtek.com

 

 

 

 

 

 

 

 

DS9284A/B-07 April 2011

2

 

 

 

 

 

 

 

 

 

 

RT9284A/B

Pin Description

 

Pin No.

Pin Name

Pin Function

 

 

 

TSOT-23-5

TSOT-23-6

 

 

 

 

 

 

 

1

 

1

LX

Switch Pin. Connect this Pin to inductor and catch diode. Minimize the track

 

area to reduce EMI.

 

 

 

 

2

 

2

GND

Ground Pin

 

 

 

 

 

 

 

 

 

Feedback Reference Voltage Pin. Series connect a resistor between WLED

3

 

3

FB

and ground as a current sense. Sense the current feedback voltage to set

 

 

 

 

the current rating.

 

 

 

 

Chip Enable (Active High). Voltage sensing input to trigger the function of

4

 

4

EN

over voltage protection. Note that this pin is high impedance. There should

 

be a pull low 100kΩ resistor connected to GND when the control signal is

 

 

 

 

 

 

 

 

floating.

--

 

5

OVP

Over Voltage Protection Pin. Voltage sensing input to trigger the function of

 

over voltage protection. Leave it unconnected to disable this function.

 

 

 

 

5

 

6

VDD

Supply Input Voltage Pin. Bypass 1uF capacitor to GND to reduce the input

 

noise.

 

 

 

 

Function Block Diagram

 

 

 

1.2MHz OSC

 

 

 

VDD

Current Bias

ibias

OCP

PWM

 

 

 

 

 

 

 

 

BandGap

VREF

750mA

Logic

 

 

 

 

 

 

 

 

Protection Circuit

 

 

 

 

LX

 

 

 

 

 

 

OVP

OVP

 

+

Buffer

 

 

 

 

 

-

 

 

 

 

UVLO

 

 

+

 

FB

 

Timer

 

 

-

VREF

GND

EN

 

 

 

 

5ms

 

Soft Start

 

 

 

 

 

 

 

 

DS9284A/B-07 April 2011

www.richtek.com

 

3

RT9284A/B

Absolute Maximum Ratings

(Note 1)

 

 

 

 

 

 

z Supply Input Voltage ----------------------------------------------------------------------------------------------------

 

 

 

 

 

 

−0.3V to 7V

z LX Input Voltage ----------------------------------------------------------------------------------------------------------

 

 

 

 

 

 

 

−0.3V to 22V

z OVP Voltage --------------------------------------------------------------------------------------------------------------

 

 

 

 

 

 

 

−0.3V to 22V

z The Other Pins -----------------------------------------------------------------------------------------------------------

 

 

 

 

 

 

 

−0.3V to 6V

z Power Dissipation, PD @ TA = 25°C

 

 

 

 

 

 

 

 

TSOT-23-5 -----------------------------------------------------------------------------------------------------------------

 

 

 

 

 

 

 

0.455W

TSOT-23-6 -----------------------------------------------------------------------------------------------------------------

 

 

 

 

 

 

 

0.455W

z Package Thermal Resistance

(Note 2)

 

 

 

 

 

 

 

 

TSOT-23-5, θJA ------------------------------------------------------------------------------------------------------------

 

 

 

 

 

 

 

220°C/W

TSOT-23-6, θJA ------------------------------------------------------------------------------------------------------------

 

 

 

 

 

 

 

220°C/W

z Lead Temperature (Soldering, 10 sec.) -----------------------------------------------------------------------------

 

 

 

 

260°C

 

 

 

z Junction Temperature ---------------------------------------------------------------------------------------------------

 

 

 

 

 

 

150°C

 

 

 

z Storage Temperature Range -------------------------------------------------------------------------------------------

 

 

 

 

 

 

65°C to 150°C

z ESD Susceptibility

(Note 3)

 

 

 

 

 

 

 

 

 

 

HBM (Human Body Mode) ---------------------------------------------------------------------------------------------

 

 

 

 

 

 

2kV

 

 

 

MM (Machine Mode) ----------------------------------------------------------------------------------------------------

 

 

 

 

 

 

200V

 

 

 

Recommended Operating Conditions (Note 4)

 

 

 

 

 

 

z Supply Input Voltage ----------------------------------------------------------------------------------------------------

 

 

 

 

 

 

2.7V to 5.5V

z Junction Temperature Range ------------------------------------------------------------------------------------------

 

 

 

 

 

 

40°C to 125°C

z Ambient Temperature Range ------------------------------------------------------------------------------------------

 

 

 

 

 

 

40°C to 85°C

Electrical Characteristics

 

 

 

 

 

 

 

 

(VIN = 3.7V, TA = 25°C unless otherwise specified)

 

 

 

 

 

 

Parameter

 

Symbol

 

Test Conditions

Min

Typ

Max

 

Unit

 

 

 

 

 

 

 

 

 

 

 

 

System Supply Input

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Operation voltage Range

 

VDD

 

 

2.7

--

5.5

 

V

 

Under Voltage Lock Out

 

VDD

 

 

1.8

2.2

2.5

 

V

 

Quiescent Current

 

 

IDD

 

FB = 1.5V, No switch

50

300

1000

 

uA

 

Supply Current

 

 

IDD

 

FB = 0V, Switch

0.1

2

3

 

mA

 

Shut Down Current

 

 

IDD

 

VEN < 0.4V

--

--

1

 

uA

 

Line Regulation

 

 

 

 

VIN : 3.0~4.3V

--

3

--

 

%

 

Oscillator

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Operation Frequency

 

 

fOSC

 

 

0.9

1.2

1.5

 

MHz

 

Maximum Duty Cycle

 

 

 

 

 

85

--

--

 

%

 

 

 

 

 

 

 

 

 

 

 

 

 

Dimming Frequency

 

 

 

 

 

100

--

100k

 

Hz

 

 

 

 

 

 

 

 

 

 

 

 

 

Reference Voltage

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Feedback Voltage

(Note 5)

 

RT9284A

 

 

1.173

1.235

1.296

 

V

 

 

 

 

 

 

 

 

 

 

 

RT9284B

 

 

0.237

0.25

0.263

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

To be continued

 

 

 

 

 

 

 

 

 

 

 

 

www.richtek.com

 

 

 

 

 

 

DS9284A/B-07

April 2011

4

 

 

 

 

 

 

 

 

 

 

 

RT9284A/B

Parameter

Symbol

Test Condition

Min

Typ

Max

Unit

MOSFET

 

 

 

 

 

 

 

 

 

 

 

 

 

On Resistance of MOSFET

RDS(ON)

 

--

0.75

--

Ω

Protection

 

 

 

 

 

 

 

 

 

 

 

 

 

OVP Threshold

VOVP

for 2,3,4 WLEDs application

14

15

16

V

 

 

 

 

for 5 WLED application

19

20

21

 

 

 

 

 

 

 

 

 

 

OVP Sink Current

 

 

--

5

--

μA

 

 

 

 

 

 

 

OCP

 

 

--

750

--

mA

 

 

 

 

 

 

 

Shut Down Voltage

VEN

 

--

--

0.4

V

Enable Voltage

VEN

 

1.5

--

--

V

Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability.

Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective thermal conductivity test board of JEDEC 51-3 thermal measurement standard.

Note 3. Devices are ESD sensitive. Handling precaution recommended.

Note 4. The device is not guaranteed to function outside its operating conditions. Note 5. Floating the OVP pin to disable OVP function.

DS9284A/B-07 April 2011

www.richtek.com

 

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