Richtek RT8561AGQW Schematic [ru]
®
RT8561A
High Voltage 8-CH LED Driver
General Description
The RT8561Ais a 40V 8-CH LEDdriver capable of delivering 30mA to each channel with 10 LEDs (3.6V per diode), total of 80 LEDs with one driver. The RT8561A is a current mode boost converter operated at 1MHz, wide VIN range covers from 6V to 24V and the on-chip current switch is 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 RT8561A automatically detects and disconnects any unconnected and/or broken strings during operation from PWM loop to prevent VOUT from over voltage.
The 1.5% matched LEDcurrents on all channels are simply programmed with a resistor or a current sink. Both analog dimming and digitally controlled PWM dimming are supported by the RT8561A. Analog dimming is linearly controlled by an external voltage. With an on-chip output clamping amplifier and a 300kΩ resistor, PWM dimming signal is easily low-pass filtered to an analog dimming signal with one external capacitor for noise-free PWM dimming. A very high contrast ratio true digital PWM dimming can be achieved by driving ACTL pin with a PWM signal.
Other protecting features include programmable output over voltage protection, LED current limit, PWM switch current limit and thermal shutdown.
The RT8561A is packaged with a tiny footprint package of WQFN-24L 4x4 packages.
Ordering Information
RT8561A 
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 requirements of IPC/JEDEC J-STD-020.
`Suitable for use in SnPb or Pb-free soldering processes.
Features
zHigh Voltage : VIN up to 24V, VOUT up to 40V, Driving up to 80 x 3.6V LEDs (10 each channel)
zChannel Current Programmable 10mA to 30mA and Matched to 1.5%
zCurrent Mode PWM 1MHz Boost Converter
zEasy Analog and Digital Dimming Control
zProgrammable Soft Start
zAutomatic Detecting Unconnected and/or Broken Channel
zProgrammable Over Voltage Protection
zDisconnects LED in Shutdown
zProviding High Accuracy Digital Dimming by PWM at ACTL Pin
zVIN Under Voltage Lockout
zOver Temperature Protection
zCurrent Limiting Protection
zSmall 24-Lead WQFN Package
zRoHS Compliant and Halogen Free
Applications
zUMPC and Notebook Computer Backlight
zGPS, Portable DVD Backlight
zDesk Lights and Room Lighting
Pin Configurations
(TOP VIEW)
|
GND |
GND |
GND |
GND |
SW |
SW |
|
|
|
24 |
23 |
22 |
21 |
20 |
19 |
|
|
LED1 |
1 |
|
|
|
|
|
18 |
VCC |
LED2 |
2 |
|
|
|
|
|
17 |
CREG |
LED3 |
3 |
|
GND |
|
|
16 |
LED8 |
|
LED4 |
4 |
|
|
|
15 |
LED7 |
||
|
|
|
|
|
||||
LED5 |
5 |
|
|
|
|
|
14 |
LED6 |
OVP |
6 |
|
|
|
|
25 |
13 |
EN |
|
|
|
|
|
||||
|
7 |
8 |
9 |
10 |
11 |
12 |
|
|
|
VC |
NC |
SS |
RISET |
ACTL |
DCTL |
|
|
|
WQFN-24L 4x4 |
|
|
|||||
Marking Information
CZ= : Product Code
CZ=YM YMDNN : Date Code
DNN
Copyright ©2012 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
DS8561A-02 April 2012 |
www.richtek.com |
|
1 |
RT8561A |
|
|
|
|
|
|
|
|
|
Typical Application Circuit |
|
|
|
|
|
|
|
|
|
VIN |
|
|
|
|
|
|
VOUT |
|
|
6V to 24V |
L |
D |
|
|
|
|
40V MAX |
|
|
|
10µH |
|
|
|
|
|
|
|
|
|
|
|
|
COUT |
|
|
|
|
|
RVIN1 |
CVIN1 |
|
|
10µF |
: |
: |
: |
: |
|
|
|
|
10 LED String |
||||||
10µF |
|
|
|
: |
: |
... : |
: |
||
10 |
|
|
|
RT8561A |
: |
: |
: |
: |
|
|
|
|
|
: |
: |
: |
: |
|
|
|
|
19, 20 SW |
|
LED1 1 |
|
|
|
|
|
|
|
18 VCC |
|
|
|
|
|
||
CVIN1 |
1k |
|
LED2 2 |
. |
|
|
|
||
13 |
|
|
|
|
|
|
|||
2.2µF |
5V |
EN |
|
|
. |
|
|
|
|
|
|
|
|
|
|
|
|||
|
|
|
|
|
|
|
|
||
VOUT |
R1 |
6 OVP |
|
LED7 15 . |
|
|
|
||
|
|
|
|
|
|||||
|
R2 |
|
|
|
LED8 16 |
RISET |
|
|
|
|
|
|
|
|
|
|
20 x 4.75 |
||
|
|
|
|
|
|
4.75k |
|
||
|
|
17 CREG |
RISET 10 |
ILED (mA) = RISET (kΩ) |
|||||
4.7µF |
|
|
|
||||||
|
9 SS |
|
|
|
|
|
|
||
|
|
|
GND 21, 22, 23, 24, 25 (Exposed Pad) |
||||||
0.1µF |
7 |
VC |
|
||||||
|
|
|
|
|
1k |
|
|
|
|
|
RVC |
12 DCTL |
|
ACTL 11 |
|
|
|
||
|
|
|
|
|
|
||||
|
1.8k |
|
|
|
|
|
PWM Signal |
||
|
CVC |
|
|
|
|
|
|||
|
|
|
|
|
|
|
|
|
|
|
3.9nF |
|
|
|
|
|
|
|
|
Figure 1. 1MHz, 20mA Full Scale Current PWM Dimming Control
VIN |
|
VOUT |
6V to 24V |
L |
40V MAX |
|
10µH |
D |
COUT
RVIN1 |
CVIN1 |
|
|
|
10µF |
: |
: |
: |
: |
|
|
|
|
|
10 LED String |
||||||
10µF |
|
|
|
|
: |
: ... |
: |
: |
||
10 |
|
|
|
|
RT8561A |
: |
: |
: |
: |
|
|
|
|
|
|
: |
: |
: |
: |
|
|
|
|
|
19, 20 SW |
|
LED1 1 |
|
|
|
|
|
|
|
|
18 VCC |
|
|
|
|
|
||
CVIN1 |
|
1k |
|
LED2 2 |
. |
|
|
|
||
|
13 |
|
|
|
|
|
|
|||
2.2uF |
5V |
|
EN |
|
|
. |
|
|
|
|
|
|
|
|
|
|
|
|
|||
VOUT |
R1 |
|
6 OVP |
|
LED7 15 . |
|
|
|
||
|
|
|
|
|
|
|||||
|
R2 |
|
|
|
|
LED8 16 |
RISET |
|
|
|
|
|
|
|
|
|
|
|
|
20 x 4.75 |
|
|
|
|
|
|
|
|
4.75k |
|
|
|
|
|
|
17 CREG |
RISET 10 |
|
ILED (mA) = RISET (kΩ) |
||||
4.7µF |
|
|
|
|
||||||
|
|
9 SS |
|
|
|
|
|
|
||
|
|
|
|
GND 21, 22, 23, 24, 25 (Exposed Pad) |
||||||
0.1µF |
|
7 VC |
|
|||||||
|
|
|
|
|
1k |
|
|
Analog |
||
|
RVC |
|
12 DCTL |
|
ACTL 11 |
|
|
|||
|
|
|
|
|
|
|||||
|
1.8k |
|
|
|
|
|
|
|
|
Dimming |
CVC
3.9nF DCTL can be floating or connected to ACTL
Figure 2. 1MHz, 20mA Full Scale Current Analog Dimming Control
Copyright ©2012 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
www.richtek.com |
DS8561A-02 April 2012 |
2
RT8561A
VIN |
|
|
|
|
6V to 24V |
L |
|
D |
|
|
10µH |
|
||
RVIN1 |
CVIN1 |
|
|
|
10µF |
|
|
||
10 |
|
|
|
|
|
|
19, 20 |
||
|
|
|
18 |
|
CVIN1 |
|
1k |
13 |
|
2.2µF |
5V |
|||
|
||||
|
|
|
||
VOUT |
R1 |
|
6 |
|
|
|
|
||
|
R2 |
|
|
|
|
|
|
17 |
|
4.7µF |
|
|
9 |
|
|
|
|
||
0.1µF |
|
|
7 |
|
RVC |
|
1k |
12 |
|
1.8k |
|
|
|
|
CVC |
|
|
|
|
3.9nF |
|
|
||
|
PWM Signal |
|
||
|
|
|
|
|
|
VOUT |
|
|
||
|
|
|
|
|
|
40V MAX |
|
|
||
|
COUT |
|
|
|
|
|
|
|
|
|
|
10µF |
|
|
: |
: |
... |
: |
: |
|
|
|
|
|
|
10 LED String |
||||||
|
|
|
|
: |
: |
: |
: |
|||
|
RT8561A |
|
|
: |
: |
|
: |
: |
|
|
|
|
|
: |
: |
|
: |
: |
|
|
|
SW |
|
|
1 |
|
|
|
|
|
|
|
VCC |
|
LED1 |
|
|
|
|
|
|
|
|
|
LED2 |
2 |
. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
EN |
|
|
|
. |
|
|
|
|
|
|
OVP |
|
LED7 |
15 . |
|
|
|
|
|
|
|
|
|
LED8 |
16 |
|
RISET |
|
|
|
|
|
|
|
|
|
|
|
ILED (mA) = |
20 x 4.75 |
|||
CREG |
RISET |
10 |
|
4.75k |
|
|||||
|
|
|
|
|
|
|
|
RISET (kΩ) |
||
SS |
|
|
|
|
|
|
|
|
|
|
VC |
|
GND 21, 22, 23, 24, 25 (Exposed Pad) |
||||||||
DCTL |
|
ACTL |
11 |
|
|
|
|
0.1µF |
|
|
|
|
|
|
|
|
|
|
|
||
Figure 3. 1MHz, 20mA Full Scale Current PWM to Analog Dimming Control
|
VIN |
|
|
|
|
|
|
VOUT |
|
4V to 36V |
|
|
|
|
|
|
|||
|
L |
D |
|
|
|
|
|
40V MAX |
|
|
10µH |
|
|
|
|
|
|
|
|
|
CVIN1 |
|
|
COUT |
|
|
|
|
|
VAVDD |
|
|
10µF |
|
: |
: |
: |
: |
|
10µF |
|
|
|
|
|||||
6V to 24V |
|
|
|
|
|
: |
: |
... : |
:10 LED String |
|
|
|
|
RT8561A |
|
: |
: |
: |
: |
|
|
19, 20 SW |
|
: |
: |
: |
: |
||
RVIN1 |
|
|
|
|
|
|
|
||
10 |
|
18 VCC |
LED1 1 |
|
|
|
|
||
|
|
|
|
|
|
||||
CVIN1 |
|
LED2 |
2 |
. |
|
|
|
||
1k |
|
|
|
|
|
||||
2.2µF |
13 EN |
|
|
|
|
|
|||
|
5V |
|
|
. |
|
|
|
||
V |
R1 |
6 OVP |
LED7 |
15 . |
|
|
|
||
|
OUT |
|
|
|
|
|
|
|
|
|
R2 |
|
|
LED8 16 |
|
RISET |
|
||
|
|
|
|
|
|
|
20 x 4.75 |
||
|
|
|
|
|
|
|
4.75k |
||
|
|
17 |
CREG |
RISET 10 |
|
ILED (mA) = RISET (kΩ) |
|||
|
|
|
|
|
|||||
4.7µF |
9 SS |
|
|
|
|
|
|
||
|
0.1µF |
7 VC |
GND 21, 22, 23, 24, 25 (Exposed Pad) |
||||||
|
RVC |
12 |
DCTL |
ACTL |
11 |
|
|
|
|
|
1.8k |
|
|
|
|
PWM Signal |
|||
|
CVC |
|
|
|
|
|
|
||
|
|
|
|
|
|
|
|
|
|
|
3.9nF |
|
|
|
|
|
|
|
|
Note :
1.Due to the limitation of maximum duty 5V input can support typically to VOUT = 33V.
2.Due to the limitation of maximum duty 4V input can support typically to VOUT = 26V.
Figure 4. Wide Range VINApplication by Connecting VCC Pin to LCDDriver Power AVDD
Copyright ©2012 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
DS8561A-02 April 2012 |
www.richtek.com |
3
RT8561A
Function Block Diagram
|
|
|
|
|
|
SW |
VCC |
|
- |
|
OSC |
|
|
|
|
|
S |
LED1 |
||
|
5.6V |
+ |
|
|
+ |
|
|
|
|
R |
|||
OVP |
|
+ |
|
|
- |
|
|
|
|
R |
|||
1.2V |
|
|
|
|||
|
- |
|
|
|
|
|
EN |
|
- |
|
|
+ - |
LED2 |
|
|
|
|
|||
|
|
|
|
+ |
||
|
1.6V |
+ |
Shutdown |
|
||
|
|
- |
||||
|
|
|
|
|
|
|
CREG |
5V |
|
|
|
|
|
LDO |
|
|
|
|
|
|
|
|
|
|
|
|
|
VC |
|
|
|
|
VOUT |
LED7 |
|
|
|
|
Regulation |
||
|
|
|
|
|
Unit |
+ |
|
|
|
|
|
|
- |
|
|
|
|
|
|
5V |
|
5uA |
|
|
|
|
|
SS |
|
|
|
|
|
|
|
|
|
|
|
|
LED8 |
|
|
|
|
|
+ |
+ |
|
|
1.2V |
|
- |
||
|
|
|
- |
|||
DCTL |
|
+ |
|
300k |
|
|
|
|
|
|
|||
|
|
- |
|
|
|
|
|
|
|
|
|
ACTL |
RISET |
Copyright ©2012 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
www.richtek.com |
DS8561A-02 April 2012 |
4
|
|
|
|
RT8561A |
|
Functional Pin Description |
|||||
Pin No. |
Pin Name |
|
|
Pin Function |
|
|
|
|
|
|
|
|
LED1, LED2, |
Channel 1 to Channel 5 LED current sink. Leave the pin unconnected if not |
|||
1, 2, 3, 4, 5 |
LED3, LED4, |
||||
|
LED5 |
used. |
|||
|
|
|
|
||
6 |
OVP |
Over Voltage Protection. PWM boost converter turns off when VOVP goes |
|||
|
|
higher than 1.2V. |
|||
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. |
|||
|
|
|
|||
11 |
ACTL |
Analog/Digital dimming control. When using analog dimming, |
|||
ILED (mA) = |
20 x 4.75 |
for VACTL ≥ 1.2V. |
|||
|
|
||||
|
|
|
|||
|
|
|
RISET (kΩ) |
||
|
|
By adding a 0.1μF filtering capacitor on the ACTL pin, the PWM dimming |
|||
12 |
DCTL |
signal on the DCTL pin will be averaged out and converted into analog |
|||
|
|
dimming signal on the ACTL pin. |
|||
|
|
|
|||
13 |
EN |
Chip enable pin, when pulled low, chip is in shutdown mode. |
|||
|
|
|
|||
14, 15, 16 |
LED6, LED7, |
Channel 6 to Channel 8 LED current sink. Leave the pin unconnected if not |
|||
LED8 |
used. |
||||
|
|||||
|
|
|
|||
17 |
CREG |
1μF capacitor should be placed on this pin to stabilize the 5V output of the |
|||
internal regulator. This regulator is for chip internal use only. |
|||||
|
|
||||
18 |
VCC |
Power supply of the chip. For good bypass, a low ESR capacitor is required. |
|||
|
|
|
|||
19, 20 |
SW |
PWM boost converter switch node. |
|||
|
|
|
|||
21, 22, 23, 24, |
GND |
Ground pin of the chip. The exposed pad must be soldered to a large PCB |
|||
25 (Exposed Pad) |
and connected to GND for maximum power dissipation. |
||||
|
|||||
|
|
|
|
|
|
Copyright ©2012 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
DS8561A-02 April 2012 |
www.richtek.com |
5
RT8561A
Absolute Maximum Ratings |
(Note 1) |
|
|
|
|
|
|
||||
z Supply Voltage, VCC ----------------------------------------------------------------------------------------------------- |
|
|
|
|
|
|
−0.3V to 28V |
||||
z SW Pin Voltage at Switching Off -------------------------------------------------------------------------------------- |
|
|
|
|
−0.3V to 45V |
||||||
z LED1 to LED8 Pin--------------------------------------------------------------------------------------------------------- |
|
|
|
|
|
|
−0.3V to 35V |
||||
z DCTL, ACTL, EN, OVP Pin Voltage ---------------------------------------------------------------------------------- |
|
|
|
|
−0.3V to 5.5V |
||||||
z Power Dissipation, PD @ TA = 25°C |
|
|
|
|
|
|
|
||||
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 |
|
|
||
Recommended Operating Conditions |
(Note 4) |
|
|
|
|
|
|||||
z Supply Input Voltage, VCC ---------------------------------------------------------------------------------------------- |
|
|
|
|
|
|
6V to 24V |
||||
z Junction Temperature Range -------------------------------------------------------------------------------------------- |
|
|
|
|
|
|
−40°C to 125°C |
||||
z Ambient Temperature Range -------------------------------------------------------------------------------------------- |
|
|
|
|
|
|
−40°C to 85°C |
||||
Electrical Characteristics |
|
|
|
|
|
|
|
||||
(VCC = 17V, TA = 25°C, unless otherwise specified) |
|
|
|
|
|
|
|||||
Parameter |
|
Symbol |
Test Conditions |
Min |
Typ |
Max |
|
Unit |
|||
|
|
|
|
|
|
|
|
|
|
|
|
Supply Current |
|
|
IVCC |
VC ≤ 0.2V (Switching off) |
-- |
3 |
5 |
|
mA |
||
VIN Under Voltage Lockout |
|
VUVLO |
VIN Rising |
|
-- |
5.6 |
5.95 |
|
V |
||
Threshold |
|
|
VIN Falling |
|
-- |
4.9 |
-- |
|
|||
|
|
|
|
|
|
||||||
Shutdown Current |
|
|
ISHDN |
VEN ≤ 0.7V |
|
-- |
-- |
10 |
|
μA |
|
EN Threshold |
|
Logic-High |
|
VEN_H |
|
|
1.6 |
-- |
5 |
|
V |
Voltage |
|
Logic-Low |
|
VEN_L |
|
|
-- |
-- |
1 |
|
|
|
|
|
|
|
|
||||||
PWM Threshold |
|
Logic-High |
|
VPWM_H |
|
|
1.3 |
-- |
5 |
|
V |
Voltage |
|
Logic-Low |
|
VPWM_L |
|
|
-- |
-- |
0.15 |
|
|
|
|
|
|
|
|
||||||
EN Pin Input Current |
|
IEN |
VEN ≤ 5V |
|
-- |
-- |
0.1 |
|
μA |
||
LED Current Programming |
|
|
|
|
|
|
|
|
|
||
LED Current |
|
|
ILED |
2V > VLED > 0.6V, RISET = 4.75kΩ, |
19 |
20 |
21 |
|
mA |
||
|
|
VACTL > 1.2V |
|
|
|||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2V > VLED > 0.6V, RISET = 4.75kΩ, |
|
|
|
|
|
|
LEDs Current Matching |
|
|
VACTL > 1.2V, Calculating |
-- |
-- |
1.5 |
|
% |
|||
|
|
|
|
|
(I(MAX) − I(MIN)) / IAverage x 100% |
|
|
|
|
|
|
RISET Pin Voltage |
|
VRISET |
3.6kΩ ≤ RISET ≤ 9.6kΩ, VACTL > 1.2V |
1.17 |
1.2 |
1.23 |
|
V |
|||
Input Current of ACTL |
|
IACTL |
0.3V ≤ VACTL ≤ 1.2V |
-- |
1 |
2 |
|
μA |
|||
|
|
|
|
|
|
|
|
|
|
|
|
Copyright ©2012 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
||||||||||
www.richtek.com |
|
|
|
|
|
|
DS8561A-02 |
April 2012 |
|||
6
Loading...