Richtek RT8561CGQW Schematic [ru]

High Voltage 8-CH LED Driver

RT8561C

General Description

The RT8561C is a 40V 8-CH LED driver capable of

delivering 30mA to each channel with 10 LEDs (3.6V per

diode), for a total of 80 LEDs with one driver. The RT8561C

is a current mode boost converter that operates at 1MHz,

with a wide V

range from 4.5V to 24V and an on chip

IN

current switch rated at 2.5A.

The PWM output voltage loop regulates the LED pins to

0.6V with an auto adjustment circuit allowing voltage

mismatches between LED strings. The RT8561C automati

cally detects and disconnects any unconnected and/or

broken strings during operation from the PWM loop to

prevent V

from over voltage.

OUT

The 1.5% matched LED currents on all channels can be

simply programmed with a resistor or a current sink. A

very high contrast ratio true digital PWM dimming can be

achieved by driving the PWM pin with a PWM signal.

Other protection features include programmable output

over voltage protection, LED current limit, PWM switch

current limit and thermal shutdown.

The RT8561C is available in a WQFN-24L 4x4 package.

Ordering Information

RT8561C

Package Type
QW : WQFN-24L 4x4 (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.

Marking Information

E4= : Product Code

E4=YM

DNN

YMDNN : Date Code

Features

z High Voltage : V
z Programma ble Channel Current from 10mA to 30mA

and Matched to 1.5%

z Current Mode PWM 1MHz Boost Converter
z Easy and High Accuracy Digital Dimming by PWM

Signal

z Programmable Soft-Start
z Automatic Detection of Unconnected and/or Broken

Channel

z Programmable Over Voltage Protection
z Disconnects LED in Shutdown
z No Power Sequence Concern
z V

Under Voltage Lockout

IN

zz

z Over Temperature Protection

zz

zz

z Current Limiting Protection

zz

zz

z Small 24-Lead WQFN Package

zz

zz

z RoHS Compliant and Halogen Free

zz

up to 24V, V

IN

up to 40V

OUT

Applications

z UMPC and Notebook Computer Backlight

z GPS, Portable DVD Backlight

z Desk Lights and Room Lighting

Pin Configurations

(TOP VIEW)

RISET GND

LX

LX

18

VCC

17

CREG

16

LED8

15

LED7

14

NC

LED6

13

EN

25

11

ACTL

LED1

LED2

LED3

LED4

LED5

OVP

GND

GND

24 2223

1

2

3

4

5

6

7

8 9 10 12

VC

NC

WQFN-24L 4x4

GND

21 20 19

GND

SS

DS8561C-00 April 2011 www.richtek.com

1

RT8561C

Typical Application Circuit

L1

VCC

EN5V

ACTL

7

VC

CREG

9

SS

GND

10µH

RT8561C

LX

LED1

LED2

LED7

LED8

OVP

RISET

...

19, 20

1

2

15

16

6

10

I

LED

V

4.5V to 24V

C8

IN

PWM Signal

R1

1.8k

C2

3.9nF

C1

R4

10µF

10

C6

1µF

R5
1k

1k

R6

C3

4.7µF

C4

0.1µF

21, 22, 23, 24,

25 (Exposed Pad)

18

13

11

17

Note :

Due to the limitation of maximum duty, 5V input can support typically to V

D1

R7

R

ISET

4.75k

(mA) =

C5
10µF

C7

...

R(k)

= 33V.

OUT

R2

R3

20 x 4.75

ISET

:
:
:
:

Ω

V

OUT

40V MAX

:

:

...

:

:

:

:

:

:

V

OUT

:

8 x 10 LED String

:
:
:

Figure 1. 1MHz, 20mA Full Scale Current PWM Dimming Control

Function Block Diagram

VCC

OVP

EN

CREG

VC

SS

ACTL

GND

4.2V

1.2V

1.6V

LDO

5V

5µA

­+

+

-

­+

Shutdown

OSC

S

R

R

+

-

V

OUT

Regulation

Unit

LX

+

-

+

-

LED1

LED2

.
.
.

+

5V

+

-

-

+

-

LED7

LED8

RISET

DS8561C-00 April 2011www.richtek.com

2

Functional Pin Description

Pin No. Pi n Na m e Pin Fun c tion

LED1, LED2,

1, 2, 3, 4, 5

6 OVP

7 VC PWM boost converter loop compensation node.

8 NC No Internal Connection.

9 SS Soft Start Pin, a capacitor of at least 10nF is required for soft start.

10 RISET A resistor or a current from DAC on this pin programs the full LED current.

LED3, LED4,
LED5

Channel 1 to Channel 5 LED current sink. Leave the pin unconnected if not
used.

Over Voltage Protection. PWM boost converter turns off when V
higher than 1.2V.

RT8561C

goes

OVP

11 ACTL

12 NC No Internal Connection.

13 EN Chip enable pin, when pulled low, chip is in shutdown mode.

14, 15, 16

17 CREG

18 VCC Power supply of the chip. For good bypass, a low ESR capacitor is required.

19, 20 LX PWM boost converter switch node.

21, 22, 23, 24,

25 (Exposed Pad)

LED6, LED7,
LED8

GND

Analog/Digital dimming control. When using analog dimming,

I ( mA) = for V 1.2V .

LED ACTL

Channel 6 to Channel 8 LED current sink. Leave the pin unconnected if not
used.

4.7μF capacitor should be placed on this pin to stabilize the 5V output of the
internal regulator. This regulator is for chip internal use only.

Ground pin of the chip. The exposed pad mus t be soldered to a large PCB
and connected to GND for maximum power dissipation.

20 x 4.75

R(k)

ISET

Ω

≥

DS8561C-00 April 2011 www.richtek.com

3

RT8561C

Absolute Maximum Ratings (Note 1)

z Supply Voltage, VCC ----------------------------------------------------------------------------------------------------- 28V

z LX Pin Voltage at Switching Off ---------------------------------------------------------------------------------------- 50V

z LED1 to LED8 Pin--------------------------------------------------------------------------------------------------------- 50V

z ACTL, EN ------------------------------------------------------------------------------------------------------------------- 24V

z OVP -------------------------------------------------------------------------------------------------------------------------- −0.3V to 5.5V

z Power Dissipation, P

WQFN-24L 4x4 ------------------------------------------------------------------------------------------------------------ 1.923W

z Package Thermal Resistance (Note 2)

WQFN-24L 4x4, θJA------------------------------------------------------------------------------------------------------- 52°C/W

WQFN-24L 4x4, θJC------------------------------------------------------------------------------------------------------ 7°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 3)

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

MM (Machine Mode) ------------------------------------------------------------------------------------------------------ 200V

@ TA = 25°C

D

Recommended Operating Conditions (Note 4)

z Supply Input Voltage, VCC---------------------------------------------------------------------------------------------- 4.5V to 24V

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

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

−40°C to 125°C

−40°C to 85°C

Electrical Characteristics

(VCC = 17V, T

Supply Current I

VIN Under Voltage Lockout
Threshold

Shutdown Current I

EN Threshold
Voltage

ACTL Threshold
Voltage

EN Pin Input Current IEN VEN ≤ 5V -- -- 0.1 μA

LED Curre nt Programming

LED Curr ent I

LEDs Current Matching

RISET Pin Voltage V

Input Current of ACTL I

V

Threshold Un-connection -- 0.1 -- V

LED

= 25°C, unless otherwise specified)

A

Parameter Symbol Test Conditions Min Typ Max Unit

VC ≤ 0.2V (Switching off) -- 3 5 mA

VCC

VIN Rising -- 4.2 4.5

Hysteresis -- 0.3 --

VEN = 0V -- -- 10 μA

1.6 -- 5

-- -- 0.65

1.3 -- 5

-- -- 0.65

2V > V

2V > V
Calculating
(I

(MAX)

3.6kΩ ≤ R

V

ACTL

> 0.6V, R

LED

> 0.6V, R

LED

= 4.75kΩ 19 20 21 mA

ISET

= 4.75kΩ

ISET

-- -- 1.5 %

− I

) / I

(MIN)

≤ 9.6kΩ, V

ISET

Average

x 100%

> 1.2V 1.17 1.2 1.23 V

ACTL

= 1.3V -- 1 2 μA

Logic-High V

Logic-Low

Logic-High V

Logic-Low

V

UVLO

SHDN

EN_H

V

EN_L

ACTL_H

V

ACTL_L

LED

RISET

ACTL

To be continued

V

V

V

DS8561C-00 April 2011www.richtek.com

4

RT8561C

Parameter Symbol Test Conditions Min Typ Max Unit

P W M Boos t Conv e r t er

Switching Frequency 0.8 1 1.2 MHz

Minimum On Time -- 100 -- ns

Regulated V

Highest Voltage LED String 0.5 0.6 0.7 V

LED

Amplifier (gm) Output Current 2.4V > VC > 0.2V -- ±15 -- μA

VC Threshold PW M Switch Off 0.1 0.2 -- V

LX R

LX Current Limit I

-- 0.3 0.5 Ω

DS(ON)

2.5 -- -- A

LIM

O VP & So f t St art

OVP Threshold V

OVP Input Curr ent I

1.1 1.2 1.3 V

OVP

V

OVP

≤ 3V -- -- 50 nA

OVP

Soft Start Current ISS VSS ≤ 2.5V 3 5 8 μA

Thermal Shutdown
Temperat ure

-- 150 -- °C

T

SD

Thermal Shutdown Hysteresis -- 20 -- °C

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. θ

Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.

is measured in the natural convection at TA = 25°C on a high effective four layers thermal conductivity test board of

JA

JEDEC 51-7 thermal measurement standard. The case point of θ

is on the expose pad for the WQFN package.

JC

DS8561C-00 April 2011 www.richtek.com

5

RT8561C

Typical Operating Characteristics

Efficiency vs. Input Voltage

100

90

80

70

60

50

40

Efficiency (%)

30

20

10

0

4 6 8 1012141618202224

Input Voltage (V)

LED Current vs. Temperature

24

23

22

21

20

19

LED Current (mA)

18

17

16

-50 -25 0 25 50 75 100 125

Temperature (°C)

80LEDs

V

= 12V

IN

LED Current vs. Input Voltage

22.0

21.6

21.2

20.8

20.4

20.0

19.6

19.2

LED Current (mA)

18.8

18.4

18.0
4 6 8 1012141618202224

Input Voltage (V)

V

vs. Te mpe rature

1.24

1.22

1.20

1.18

(V)

1.16

RISET

V

1.14

1.12

1.10

-50 -25 0 25 50 75 100 125

RISET

Temperature (°C)

LED1

LED2

LED3

LED4

LED5

LED6

LED7

LED8

V

IN

= 12V

V

vs. Input Voltage

1.25

1.24

1.23

1.22

1.21

(V)

1.20

RISET

1.19

V

1.18

1.17

1.16

1.15
4 6 8 1012141618202224

RISET

25

20

15

10

LED Current (mA)

Input Voltage (V)

LED Curre nt vs. PWM Duty Cycle

PWM = 200Hz

PWM = 1kHz

PWM = 10kHz

PWM = 30kHz

5

V

= 0V to 3V, V

0

0 0.1 0.2 0 .3 0.4 0.5 0.6 0.7 0.8 0.9 1

0 10 20 30 40 50 60 70 80 90 100

PWM

Duty Cycle (%)

IN

= 12V

DS8561C-00 April 2011www.richtek.com

6

RT8561C

Shutdown Current vs. Input Voltage

10

8

6

4

2

Shutdown Current (μA) 1

0

4 6 8 1012141618202224

Input voltage (V)

Switch Off Current vs. Input Voltage

4.0

3.8

3.6

3.4

3.2

3.0

2.8

2.6

2.4

Switch Off Current (mA)

2.2

2.0
4 6 8 1012141618202224

Input Voltage (V)

V

COMP

Shutdown Current vs. Temperature

6

5

4

3

2

Shutdown Current (μA) 1

1

V

= 12V, V

V

= 0V

EN

0

-50 -25 0 25 50 75 100 125

IN

EN

= 0V

Temperature (°C)

SS Current vs. Temperature

8.0

7.6

7.2

6.8

6.4

6.0

5.6

SS Current (μA)

5.2

4.8

= 0V

4.4

4.0

-50 -25 0 25 50 75 100 125

Temperature (°C)

V

IN

= 12V, C

= 0.1μF

SS

SS Current vs. Input Voltage

6.0

5.8

5.6

5.4

SS Current (μA)

5.2

C

5.0
4 6 8 1012141618202224

Input Voltage (V)

= 0.1μF

SS

OVP Voltage (V)

1.30

1.28

1.26

1.24

1.22

1.20

1.18

1.16

1.14

1.12

1.10

OVP Voltage vs. Temperature

V

= 12V

IN

-50 -25 0 25 50 75 100 125

Temperature (°C)

DS8561C-00 April 2011 www.richtek.com

7

RT8561C

1.4

1.2

1.0

0.8

0.6

OVP Voltage (V)

0.4

0.2

0.0

EN

(2V/Div)

OVP Voltage vs. Input Voltage

4 6 8 1012141618202224

Input Voltage (V)

Power On from EN

14V

12V

10V

I

OUT

(100mA/Div)

V

IN

Line Transient Response

V

= 10.8V to 13.2V

IN

Time (50ms/Div)

V

OUT

(20V/Div)

LX

(20V/Div)

I

IN

(100mADiv)

Time (10ms/Div)

V

= 12V

IN

DS8561C-00 April 2011www.richtek.com

8

Applications Information

RT8561C

The RT8561C is a current mode boost converter operating

at 1MHz to power up to 80 white LEDs with a

programmable current for uniform intensity. The part

integrates current sources, soft-start, and easy analog

and digital dimming control. The protection block provides

the circuitry for over temperature, over voltage and current

limit protection features.

Input UVLO

The input operating voltage range of the RT8561C is 4.5V

to 24V. An input capacitor at the VCC pin can reduce

ripple voltage. It is recommended to use a ceramic 10μF

or larger capacitor as the input capacitor. This IC provides

an Under Voltage Lockout (UVLO) function to enhance

the stability during startup.

Soft-Start

The RT8561C employs a soft-start feature to limit the inrush

current. The soft-start circuit prevents excessive inrush

current and input voltage droop. The soft-start time is

determined by the capacitor, C4, which is connected to

the SS pin with 5μA constant current. The value of capacitor

C4 is user defined to satisfy the designer's requirement.

LED Connection

The RT8561C provides an 8-CH LED driver with each

channel capable of supporting up to 10 LEDs. The 8 LED

strings are connected from V

to pins 1, 2, 3, 4, 5, 14,

OUT

15, and 16 respectively. If one of the LED channels is not

in use, the LED pin should be tied to ground directly.

Setting and Regulation of LED Current

The LED current can be calculated by the following

equation :

I(mA) =

LED

where, R

20 x 4.75

R(k)Ω

ISET

is the resistor between the RISET pin and

ISET

GND.

This setting is the reference for the LED current at LED1

to LED8 and represents the sensed LED current for each

string. The DC/DC converter regulates the LED current

according to the setting.

If VIN is close to V

and smaller than V

OUT

, the control

OUT

loop may turn on the power switch with minimum on time

and then skip cycles to maintain LED current regulation.

Brightness Control

The RT8561C features digital dimming control scheme.

A very high contrast ratio true digital PWM dimming can

be achieved by driving the ACTL pin with a PWM signal at

the recommended PWM frequency range from 100Hz to

10kHz.

Dimming frequency can be sufficiently adjusted from

100Hz to 30kHz. However, LED current cannot be 100%

proportional to duty cycle especially for high frequency

and low duty ratio because of physical limitation caused

by inductor rising time. Refer to Table 1 and Figure 2.

Table 1.

Dimming Frequency (Hz) Duty (Min.) Duty (Max.)

100 < f
200 < f
500 < f
1k < f
2k < f
5k < f
10k < f

Note : The minimum duty in Table 1 is based on the application

circuit and does not consider the deviation of current linearity.

≤ 200 0.16% 100%

PWM

≤ 500 0.40% 100%

PWM

≤ 1k 0.80% 100%

PWM

≤ 2k 1.60% 1 00%

PWM

≤ 5k 4.00% 1 00%

PWM

≤ 10k 8.00% 1 00%

PWM

≤ 20k 16.0 0% 100%

PW M

LED Curre nt vs. PWM Duty Cycle

25

20

15

PWM = 200Hz

10

LED Current (mA)

5

V

0

0 0.1 0.2 0 .3 0.4 0.5 0.6 0.7 0.8 0.9 1

0 10 20 30 40 50 60 70 80 90 100

PWM

Duty Cycle (%)

PWM = 1kHz

PWM = 10kHz

PWM = 30kHz

= 0V to 3V, V

IN

= 12V

Figure 2. LED Current vs. PWM Dimming Duty Cycle

DS8561C-00 April 2011 www.richtek.com

9

RT8561C

Over Voltage Protection

The RT8561C equips an Over Voltage Protection (OVP)

function. When the voltage at the OVP pin reaches a

threshold of approximately 1.2V, the MOSFET driver

output (LX) will be turned “OFF”. The MOSFET driver
output (LX) will be turned “ON” again once the voltage at

OVP drops below the threshold voltage 1.2V.

Thus, the output voltage can be clamped at a certain

voltage level as shown in the following equation :

R2

V = V1+

OUT, OVP OVP

⎛⎞

×

⎜⎟

R3

⎝⎠

where

R2 and R3 are the resistors in a voltage divider connected

to the OVP pin.

V

is typically 1.2V.

OVP

If at least one string is in normal operation, the controller

will automatically ignore the open strings and continue to

regulate the current for the string(s) in normal operation.

Current Limit Protection

The RT8561C can limit the peak current to achieve over

current protection. The RT8561C senses the inductor

current through the LX pin during the switch on period.

The duty cycle depends on the current sense signal

summed up with the internal slope compensation and

compared to the VC signal. The internal N-MOSFET will

be turned off when the current signal is larger than the

COMP signal. In the off period, the inductor current will

descend. The internal MOSFET is turned on by the

oscillator in the next beginning cycle.

Hence, even when VIN is ready, the control circuit will

still wait for the arrival of PWM and EN before the LEDs

can react :

VIN

VOUT

EN

ACTL

UVLO

Figure 3. EN/ACTL Prior to VIN

VIN

VOUT

EN

ACTL

UVLO

Figure 4. VIN Tums Off Prior to EN/ACTL

VIN

VOUT

EN

ACTL

Over Temperature Protection

The RT8561C has an Over Temperature Protection (OTP)

function to prevent excessive power dissipation from

overheating the device. The OTP will shut down switching

operation when the junction temperature exceeds 150°C.

The main converter will start switching again once the

junction temperature cools down approximately by 20°C.

Power Sequence

The RT8561C can apply these power on/off sequences

among VLED, EN and ACTL as shown in the charts below.

10

Figure 5. EN Prior to ACTL Signal

VIN

VOUT

EN

ACTL

Figure 6. EN Prior to ACTL Signal

DS8561C-00 April 2011www.richtek.com

RT8561C

VIN

VOUT

EN

ACTL

Figure 7. ACTL Prior to EN Signal

VIN_POK

ACTL

EN

LED_ON

Figure 8

Inductor Selection

The value of the output inductor (L), where the transition

from discontinuous to continuous mode occurs is

approximated by the following equation :

2

(V V V

OUT IN IN

L =

2I f V

×××

OUT OUT

)

−×

2

Diode Selection

Schottky diode is a good choice for an asynchronous boost

converter due to its small forward voltage. However, when

selecting a Schottky diode, important parameters such

as power dissipation, reverse voltage rating and pulsating

peak current should all be taken into consideration.

Choose a suitable diode with reverse voltage rating greater

than the maximum output voltage.

Capacitor Selection

The input capacitor reduces current spikes from the input

supply and minimizes noise injection into the converter.

For most applications, a 10μF ceramic capacitor is

sufficient. A value higher or lower may be used depending

on the noise level from the input supply and the input

current to the converter.

It is recommended to choose a ceramic capacitor based

on the output voltage ripple requirements. The minimum

value of the output capacitor C

is approximately given

OUT

by the following equation :

(V V ) I

−×

C =

OUT

OUT IN OUT

VVf

η

×××

RIPPLE OUT

where,

V

= maximum output voltage.

OUT

VIN = minimum input voltage.

f = operating frequency.

I

= sum of current from all LED strings.

OUT

η is the efficiency of the power converter.

The boost converter operates in discontinuous mode over

the entire input voltage range when the L1 inductor value

is less than this value L. With an inductance greater than

L, the converter operates in continuous mode at the

minimum input voltage and may be discontinuous at higher

voltages.

The inductor must be selected with a saturation current

rating greater than the peak current provided by the

following equation :

VI VTV V

I =

PEAK

××−

OUT OUT IN OUT IN

η

××

+

V2LV

IN OUT

⎛⎞
⎜⎟
⎝⎠

Thermal Considerations

For continuous operation, do not exceed absolute

maximum junction temperature. The maximum power

dissipation depends on the thermal resistance of the IC

package, PCB layout, rate of surrounding airflow, and

difference between junction and ambient temperature. The

maximum power dissipaton can be calculated by the

following formula :

P

where T

D(MAX)

= (T

J(MAX)

− TA) / θ

J(MAX)

JA

is the maximum junction temperature, TA is

the ambient temperature, and θJA is the junction to ambient

thermal resistance.

For recommended operating condition specifications of

RT8561C, the maximum junction temperature is 125°C

and TA is the ambient temperature. The junction to ambient

thermal resistance, θJA, is layout dependent. For WQFN-

24L 4x4 packages, the thermal resistance, θJA, is 52°C/

W on a standard JEDEC 51-7 four-layer thermal test board.

The maximum power dissipaton at T

= 25°C can be

A

calculated by the following formula :

DS8561C-00 April 2011 www.richtek.com

11

RT8561C

P

= (125°C − 25°C) / (52°C/W) = 1.923W for

D(MAX)

WQFN-24L 4x4 package

The maximum power dissipation depends on the operating

ambient temperature for fixed T

and thermal

J(MAX)

resistance, θJA. For the RT8561C package, the derating

curve in Figure 9 allows the designer to see the effect of

rising ambient temperature on the maximum power

dissipation.

2.40

2.00

1.60

1.20

0.80

0.40

Maximum Power Dissipation (W) 1

0.00
0 25 50 75 100 125

Ambient Temperature (°C)

Four-Layer PCB

LED1

LED2

LED3

LED4

LED5

OVP

C8

Place these components
as close as possible.

D

RISET GND

LX

11

ACTL

LX

25

NC

GND

24 2223

1

2

3

4

5

6

7

VC

R1

C2

GND

GND

GND

21 20 19

GND

8 9 10 12

SS

NC

Locate the compensation
components to VC pin as
close as possible.

Figure 10. PCB Layout Guide

18

17

16

15

14

13

C5

L

VCC

CREG

LED8

LED7

LED6

EN

V

OUT

GND

C1

V

IN

GND

C6

Locate the C6 as
close to VCC pin as
possible.

R4

Figure 9. Derating Curve for RT8561C Package

Layout Guideline

PCB layout is very important for designing power switching

converter circuits. Some recommended layout guides that

should be strictly be followed are shown as follows :

` The power components L

, D1, C

1

VIN1

, C

OUT1

and C

OUT2

must be placed as close as possible to reduce the ac

current loop. The PCB trace between power components

must be short and wide as possible due to large current

flow these trace during operation.

` Place L

and D1 connected to LX pin as close as possible.

1

The trace should be short and wide as possible.

` Recommend place C

` Pin7 is the compensation point to adjust system

close to VCC pin.

VIN2

stability. Place the compensation components to pin7

as close as possible, no matter the compensation is

RC or capacitance.

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DS8561C-00 April 2011www.richtek.com

Outline Dimension

RT8561C

D

E

A

A3

A1

D2

SEE DETAIL A

1

be

E2

L

1
2

1
2

DETAIL A

Pin #1 ID and Tie Bar Mark Options

Note : The configuration of the Pin #1 identifier is optional,

but must be located within the zone indicated.

Dimensions In Millimeters Dimensions In Inche s

Symbol

Min Max Min Max

A 0.700 0.800 0.028 0.031

A1 0.000 0.050 0.000 0.002

A3 0.175 0.250 0.007 0.010

b 0.180 0.300 0.007 0.012

D 3.950 4.050 0.156 0.159

D2 2.300 2.750 0.091 0.108

E 3.950 4.050 0.156 0.159

E2 2.300 2.750 0.091 0.108

e 0.500 0.020

L 0.350 0.450

Richtek Technology Corporation

Headquarter

5F, No. 20, Taiyuen Street, Chupei City

Hsinchu, Taiwan, R.O.C.

Tel: [phone] Fax: [phone]

0.014 0.018

W-Type 24L QFN 4x4 Package

Richtek Technology Corporation

Taipei Office (Marketing)

5F, No. 95, Minchiuan Road, Hsintien City

Taipei County, Taiwan, R.O.C.

Tel: [phone] Fax: [phone]

Email: [e-mail]

Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit

design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be

guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.

DS8561C-00 April 2011 www.richtek.com

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