Richtek RT8463GCP, RT8463GQW Schematic

®

High Voltage Multi-Topology LED Driver

RT8463

General Description

The RT8463 is a current mode PWM regulator for LED

driving applications. With a 2A power switch, wide input

voltage (4.5V to 50V) and output voltage (up to 50V)

ranges, the RT8463 can operate in any of the three

common topologies : Buck, Boost or Buck-Boost.

With 470kHz operating frequency, the size of the external

PWM inductor and input/output capacitors can be

minimized. High efficiency is achieved by a 100mV current

sensing control.

Brightness dimming can be controlled from either analog

or PWM signal. A unique built-in clamping comparator

and filtering resistor allow easy low noise analog dimming

conversion from PWM signal with only one external

capacitor.

The RT8463 is available in the TSSOP-14 (Exposed pad)

and WDFN-12L 3x3 packages.

Ordering Information

RT8463

Package Type CP : TSSOP-14 (Exposed Pad) QW : WDFN-12L 3x3 (W-Type)

Lead Plating System G : Green (Halogen Free and Pb Free)

Note :

Richtek products are :

` RoHS compliant and compatible with the current require-

ments of IPC/JEDEC J-STD-020.

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

Features

zz

z High Voltage : V

zz

z Buck, Boost or Buck-Boost Operation

zz

z Built-In 2A Power Switch

zz

z Current Mode PWM Control

zz

z 470kHz Fixed Switching Frequency

zz

z Easy Dimming : Analog, PWM Digital or PWM

zz

Up to 50V, V

IN

Up to 50V

OUT

Converting to Analog with One External Capacitor

zz

z Adjustable Soft-Start to Avoid Inrush Current

zz

z Adjustable Over V oltage Protection to Limit Output

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Voltage

zz

z Thermal Shutdown

zz

z Under Voltage Lockout

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z RoHS Compliant and Halogen Free

zz

Applications

z GPS, Portable DVD Backlight

z Desk Lights and Room Lighting

z Industrial Display Backlight

Marking Information

RT8463GCP

RT8463GCP : Product Number

RT8463 GCPYMDNN

RT8463GQW

98=YM

DNN

YMDNN : Date Code

98 = : Product Code

YMDNN : Date Code

Simplified Application Circuit

V

IN

5V

PWM Dimming Control

R1

C2

©

C3

C1

VCC EN

DCTL

VC SS ACTL

C4

L

RT8463

SW ISP ISN

OVP

CREG

GND

DS8463-00 January 2013 www.richtek.com

D1

C5

R4

R2

R3

V

C6

V

OUT

1

RT8463

Pin Configurations

ISP ISN

VC ACTL DCTL

EN

GND

2

3

4

GND

5

6

7

(TOP VIEW)

14

VCC

13

CREG

12

SW

11

GND

10

SS

9

15

OVP

8

GND

1

ISP

2

ISN

3

VC

4

ACTL

5

DCTL

67

EN

GND

12

VCC

11

CREG

10

SW

9

GND

8

SS

13

OVP

TSSOP-14 (Exposed Pad)

Functional Pin Description

Pin No.

TSSOP-14

(Exposed Pad)

WDFN-12L 3x3

1 1 ISP Positive Current Sense Input.

2 2 ISN

3 3 VC Compensation Node for PWM Boost Converter Loop.

4 4 ACTL

5 5 DCTL

6 6 EN

7, 8, 11, 15

(Exposed Pad)

13 (Exposed Pad)

9,

9 7 OVP

10 8 SS

12 10 SW Switch Node of PWM Boost Converter.

13 11 CREG

14 12 VCC

Pin Name Pin Function

GND

WDFN-12L 3x3

Negative Current Sense Input. Voltage threshold between ISP and ISN is 100mV.

Analog Dimming Control Input. Effective programming range is between 0.2V and 1.2V.

Digital Dimming Control Input. By adding a 0.47μF filtering capacitor on the ACTL pin, the PWM dimming signal on DCTL pin will be averaged and converted into analog dimming signal on the ACTL pin. V

= 1.2V x PWM dimming duty cycle.

ACTL

Enable Control Input (Active High). When this pin is low, the chip is in shutdown mode.

Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation.

Over Voltage Protection Sense Input. The PWM Boost converter turns off when V

goes higher than 1.2V.

OVP

Soft-Start Time Setting. A minimum 10nF capacitor is required for soft-start.

Regulator Output for Internal Circuit. Placed a 1μF capacitor to stabilize the 5V output regulator.

Power Supply Voltage Input. For good bypass, a low ESR capacitor is required.

2

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DS8463-00 January 2013www.richtek.com

Function Block Diagram

RT8463

SW

VCC

OVP

EN

VC

SS

DCTL

4.5V

1.2V

1.4V

V

ISP

100

+

-

+

-

1.2V

+

-

– V

(mV)

ISN

Shutdown

5µA

OSC

ACTL

5V

S

R

+

-

GM

+

-

LDO

CREG

ISN

ISP

GND

V

(V)

0

0.2 1.2

ACTL

Figure 1

Operation

The RT8463 is specifically designed to be operated in

Buck, Boost and Buck-Boost converter applications. This

device uses a fixed frequency, current mode control

scheme to provide excellent line and load regulations. The

control loop has a current sense amplifier to sense the

voltage between the ISP and ISN pins and provides an

output voltage at the VC pin. A PWM comparator then

turns off the internal power switch when the sensed power

switch current exceeds the compensated VC pin voltage.

The power switch will not reset by the oscillator clock in

each cycle. If the comparator does not turn off the switch

in a cycle, the power switch is on for more than a full

DS8463-00 January 2013 www.richtek.com

©

switching period until the comparator is tripped. In this

manner, the programmed voltage across the sense

resistor is regulated by the control loop.

The current through the sense resistor is set by the

programmed voltage and the sense resistance. The voltage

across the sense resistor can be programmed by either

the analog or PWM signals at the ACTL pin, or the PWM

signal at the DCTL pin.

The RT8463 provides protection functions which include

over temperature, input voltage under voltage, output

voltage over voltage, and switch current limit.

3

RT8463

Absolute Maximum Ratings (Note 1)

z Supply Input Voltage, VCC ------------------------------------------------------------------------------------ −0.3V to 60V

z SW Pin Voltage at Switching Off, ISP, ISN ---------------------------------------------------------------- −0.3V to 60V

z DCTL, ACTL, CREG, OVP Pin Voltage -------------------------------------------------------------------- −0.3V to 5.5V (Note 2)

z EN Pin Voltage --------------------------------------------------------------------------------------------------- −0.3V to 20V

z Power Dissipation, P

TSSOP-14 (Exposed Pad) ------------------------------------------------------------------------------------ 3.32W

WDFN-12L 3x3 --------------------------------------------------------------------------------------------------- 3.28W

z Package Thermal Resistance (Note 3)

TSSOP-14 (Exposed Pad), θJA------------------------------------------------------------------------------ 30.1°C/W

TSSOP-14 (Exposed Pad), θJC------------------------------------------------------------------------------ 7.5°C/W

WDFN-12L 3x3, θJA--------------------------------------------------------------------------------------------- 30.5°C/W

WDFN-12L 3x3, θJC--------------------------------------------------------------------------------------------- 7.5°C/W

z Junction Temperature ------------------------------------------------------------------------------------------- 150°C

z Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------- 260°C

z Storage Temperature Range ---------------------------------------------------------------------------------- −65°C to 150°C

z ESD Susceptibility (Note 4)

HBM (Human Body Model)------------------------------------------------------------------------------------ 2kV

MM (Machine Model) ------------------------------------------------------------------------------------------- 200V

@ TA = 25°C

D

Recommended Operating Conditions (Note 5)

z Supply Input Voltage, VCC ------------------------------------------------------------------------------------ 4.5V to 50V

z Junction Temperature Range---------------------------------------------------------------------------------- −40°C to 125°C

z Ambient Temperature Range ---------------------------------------------------------------------------------- −40°C to 85°C

Electrical Characteristics

(VCC = 12V, No Load on any Output, T

Parameter Symbol Test Conditions Min Typ Max Unit

Overall

Regulator Output Voltage V

Supply Current I

VIN Under Voltage Lockout Threshold

Shutdown Current I

Logic-High V

EN Input Voltage

Logic-Low V

EN Input Current VEN > 2V -- -- 1 μA

Current Sens e Amplifier

= 25°C, unless otherwise specified)

A

I

CREG

VC ≤ 0.2V (Not Switching ) -- -- 5 mA

VCC

= 20mA 4.5 5 5.5 V

CREG

VIN Rising -- 4.2 --

V

UVLO

VEN < 0.5V -- -- 15 μA

SHDN

2 -- --

EN_H

-- -- 0.5

EN_L

Falling -- 3.8 --

V

IN

V

≥ 1.25V 96 100 102

Input Threshold (V

ISP

− V

)

ISN

ACTL

= 1.2V 95 98 101

V

ACTL

4

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DS8463-00 January 2013www.richtek.com

mV

RT8463

Parameter Symbol Test Conditions Min Typ Max Unit

Input Current I

Output Current IVC 2V > VC > 0. 2V -- ±10 -- μA

VC Threshold for PWM Switch Off -- 0.2 -- V

LED Dimming

Analog Dimming ACTL Pin Input Current

LED C ur rent On Threshold at ACTL

LED C ur rent Off Threshold at ACTL

DCTL Input Current I

DCTL Input Voltage

Logic-High V

Logic-Low V

PWM Boost Converter

Switching Frequency fSW 420 470 520 kHz

V

ISP

V

ISN

I

0 ≤ V

ACTL

V

ACTL_ON

V

ACTL_OFF

DCTL

DCTL_H

DCTL_L

(V

-- 0.2 0.25 V

0.3V ≤ V

2 -- --

-- -- 0.1

= 24V -- 200 -- μA

ISP

= 24V -- 20 -- μA

ISN

≤ 3V, DCTL Floating -- -- 2 μA

ACTL

ISP

− V

) = 100mV -- 1.2 1.33 V

ISN

≤ 5V -- 0.5 2 μA

DCTL

V

Maximum Duty Cycle D

-- -- 100 %

MAX

Minimum On-Time (Note 6) -- 150 250 ns

SW R

SW Current Limit I

-- 0.3 0.5 Ω

DS(ON)

LIM_SW

2 2.5 -- A

OVP and Soft-Start

OVP Threshold V

OVP Input Current I

Soft-Start SS Pin Current ISS V

1.15 1.2 1.25 V

OVP

V

OVP

≤ 1.5V -- -- 50 nA

OVP

≤ 2.5V -- 5 8 μA

SS

Temperature Protection

Thermal Shutdown Temperature

Thermal Shutdown Hysteresis

Note 1. Stresses beyond those listed “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 in

the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may

affect device reliability.

Note 2. If connected with a 20kΩ serial resistor, ACTL and DCTL can go up to 40V. Note 3. θ

Note 4. Devices are ESD sensitive. Handling precaution is recommended. Note 5. The device is not guaranteed to function outside its operating conditions. Note 6. Guaranteed by design, not subjected to production test.

is measured at T

JA

measured at the exposed pad of the package.

= 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is

A

T

SD

ΔT

SD

-- 150 -- °C

-- 20 -- °C

DS8463-00 January 2013 www.richtek.com

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5

RT8463

Typical Application Circuit

V

4.5V to 50V

PWM Dimming control

4.5V to 50V

IN

5V

R1

10k

C2

3.3nF

V

IN

Analog

Dimming

5V

R1

10k

C2

3.3nF

D1

C1

R2

100mV

C5 1µF

L

22µH

C3 10nF

C4

0.47µF

VCC

EN

DCTL

VC

SS

ACTL

RT8463

ISP

ISN

OVP

GND

CREG

SW

Figure 2. PWM to Analog Dimming Buck Configuration

D1

C1

R2

100mV

C5 1µF

L

15µH

C3 10nF

VCC

ACTL

DCTL

EN

VC

SS

RT8463

ISP

ISN

OVP

GND

CREG

SW

R3 R4

C6

R3 R4

C6

Figure 3. Analog Dimming Buck Configuration

V

4.5V to 50V

IN

PWM Dimming control

5V

R1

10k

C2

3.3nF

C3 10nF

C1

VCC

ACTL

DCTL

EN

VC

SS

RT8463

ISP

ISN

OVP

GND

CREG

SW

R2

100mV

C5 1µF

15µH

D1

R3 R4

C6

L

Figure 4. PWM Dimming Buck Configuration Through ACTL Pin

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DS8463-00 January 2013www.richtek.com

Richtek RT8463GCP, RT8463GQW Schematic [ru]