MPS MP4600DQ High-voltage wled driver for large panel tv backlighting Datasheet

MP4600
High-Voltage WLED Driver For
Large Panel TV Backlighting
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP4600 is an integrated white LED driver.
It can be applied with MPS patent pending
technology to drive up to 55 inch LCD TV
backlighting, in which the LED string voltage
can be up to 300V. The novel technology can
leverage the LED drive power by regulating
only a small part of the LED drive voltage. As a
result, working together with a fixed high
voltage source, a low voltage LED driver can be
used to drive the high voltage LED strings with
super high power density, high efficiency and
low cost due to the low voltage stress, high
switching frequency, and smaller size of
passive components.
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MP4600 is a current mode controlled buckboost regulator. With a 12V input VINL and a
high voltage source VINH, it can deliver a
regulated voltage (VINH to VINH+43V) to drive a
LED string with up to 85 LEDs. It incorporates
both DC and PWM dimming onto a single
control pin. Fault protection includes LED open
strings protection, output short circuit protection,
input over voltage protection, cycle-by-cycle peak
current limiting, and thermal shutdown.
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Novel Power Leverage Control Technology
Unique Step-up/down Operation
0.28Ω Internal Power MOSFET Switch
Adjustable Switching Frequency
Analog and PWM Dimming
0.198V Reference Voltage
5μA Shutdown Mode
Stable with Low ESR Output Ceramic
Capacitors
Cycle-by-Cycle Over Current Protection
Thermal Shutdown Protection
Open Strings Protection
Input Over Voltage Protection
Output Short Circuit Protection
Available in 10-Pin 3x3mm QFN Packages
APPLICATIONS
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TV Backlighting
Large LCD Panels Backlighting
“MPS” and “The Future of Analog IC Technology” are Trademarks of Monolithic
Power Systems, Inc.
The MP4600 is available in 10-pin 3x3mm QFN
packages.
MP4600 Rev. 0.91
1/6/2012
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
1
MP4600 – WHITE LED DRIVER FOR UP TO 55 INCH TV BACKLIGHTING
ORDERING INFORMATION
Part Number*
Package
Top Marking
Free Air Temperature (TA)
MP4600DQ
QFN10 (3x 3mm)
9M
-40°C to +85°C
For Tape & Reel, add suffix –Z (e.g. MP4600DQ–Z);
For RoHS Compliant Packaging, add suffix –LF (e.g. 4600DQ–LF–Z)
PACKAGE REFERENCE
TOP VIEW
VDD
1
10
SW
VSS
2
9
BST
OVP
3
8
INGND
FB
4
7
EN/DIM
COMP
5
6
RSET
EXPOSED PAD
ON BACKSIDE
(Connect to VSS)
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
Supply Voltage VDD – VSS............................. 60V
VSW – VSS ..............................-0.3V to VIN + 0.3V
VBST ...................................................... VSW + 6V
VOVP – VSS .......................................-0.3V to +6V
VEN – VINGND.....................................-0.3V to +6V
VDIM – VINGND....................................-0.3V to +6V
VINGND – VSS .....................................-0.3V to 60V
Continuous Power Dissipation
(TA = +25°C)(2)
............................................................. 2.5W
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature............... -65°C to +150°C
3x3 QFN10 ............................. 50 ...... 12... °C/W
Recommended Operating Conditions
(3)
(4)
θJA
θJC
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/θJA. Exceeding the maximum allowable power
dissipation will cause excessive die temperature, and the
regulator will go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
3) The device function is not guaranteed outside of the
recommended operating conditions.
4) Measured on JESD5 1-7, 4-layer PCB.
Supply Voltage VDD – VSS.................4.5V to 55V
Ambient Junct. Temp (TJ) ........ -40°C to +125°C
MP4600 Rev. 0.91
1/6/2012
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
2
MP4600 – WHITE LED DRIVER FOR UP TO 55 INCH TV BACKLIGHTING
ELECTRICAL CHARACTERISTICS
VDD = 12V, TA = +25°C, all voltages with respect to VSS, unless otherwise noted.
Parameters
Feedback Voltage
Feedback Current
Switch-On Resistance
Switch Leakage
Current Limit
Symbol
VFB
IFB
RDS(ON)
ISW-LK
ILIMIT
Oscillator Frequency
fS
Default Oscillator Frequency
fS-Default
Fold-back Frequency
Maximum Duty Cycle
Minimum On-Time
Under Voltage Lockout Threshold Rising
Under Voltage Lockout Threshold Hysteresis
fS-FB
DMAX
tON
VDD-TH
VDD-HYS
EN Input Current
IEN
EN OFF Threshold (w/Respect to INGND)
EN ON Threshold (w/Respect to INGND)
Minimum EN Dimming Threshold
Maximum EN Dimming Threshold
PWM Dimming Frequency (5)
Supply Current (Quiescent)
Supply Shut Down Current
Thermal Shutdown
Thermal Shutdown Hysteresis
Open LED OV Threshold
Open LED OV Hysteresis
Condition
VDD=4.5V to 55V
VFB = 0.22V
Min
0.188
-50
Typ
0.198
Max
0.208
50
3.0
Units
V
nA
Ω
μA
A
0.5
MHz
1.35
MHz
250
90
100
3.3
100
2.1
0.1
kHz
%
ns
V
mV
0.28
VEN = 0V, VSW = 0V
1
VFB = 0.1V,
RST=100kΩ
VFB = 0.1V, RST
open
VFB = 0V, VOVP=0V
VFB = 0.1V
3.0
VEN = 2V
VEN = 0V
VEN Falling
VEN Rising
VENL
VENH
VDIML
VDIMH
fPWM
IQ
VEN = 2V, VFB = 1V
IOFF
VEN = 0V
TTH
THYS
VOVP-TH
VOVP-HYS
3.6
μA
0.4
0.6
1.25
100
1.1
0.7
1.4
0.8
3.4
150
20
1.2
60
0.6
0.8
1.5
20k
1.0
15
1.3
V
V
V
V
Hz
mA
μA
°C
°C
V
mV
Note:
5) Guaranteed by design.
MP4600 Rev. 0.91
1/6/2012
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
3
MP4600 – WHITE LED DRIVER FOR UP TO 55 INCH TV BACKLIGHTING
PIN FUNCTIONS
Pin #
Name
1
VDD
2
VSS
3
OVP
4
FB
5
COMP
6
RSET
7
EN/DIM
8
INGND
9
BST
10
SW
MP4600 Rev. 0.91
1/6/2012
Description
Positive Voltage Input Pin. A decoupling cap is needed to prevent large voltage spikes from
appearing at the input.
Negative Voltage Output Pin. This pin is the voltage reference for OVP, FB, COMP and
RSET pins. This node should be placed away from switching noise sources. The exposed
pad is connected to this pin.
Over Voltage Protection Pin. Use one external resistor voltage divider across INGND and
VSS to program OVP threshold. Its voltage is referred to VSS. When the OVP pin voltage
reaches the shutdown threshold 1.2V, the switch will be turned off and will recover when OVP
voltage decreases sufficiently. When the OVP pin voltage is lower than 0.4V and FB pin
voltage is lower than 0.1V, the chip frequency will be folded back. Program the OVP pin
voltage from 0.4V to 1.2V for normal operation.
LED Current Feedback Input. MP4600 regulates the voltage across the current sensing
resistor between FB and VSS. Connect the current sensing resistor from the bottom of the
LED strings to VSS. The FB pin is connected to the bottom of the LED strings. The regulation
voltage is 0.198V.
Output of error amplifier. Connect a 1nF or larger capacitor on COMP to improve the stability
and to provide a soft on at start up or PWM dimming.
Connect to a resistor to VSS to set the switching frequency.
On/Off Control Input and Dimming Command Input. Its voltage is referred to INGND. A
voltage greater than 0.7V will turn on the chip. When the EN/DIM pin voltage rises from 0.7V
to 1.4V, the LED current will change from 0% to 100% of the maximum LED current. To use
PWM dimming, apply a 100Hz to 20kHz square wave signal with amplitude greater than 1.5V
to this pin.
Input Ground Reference. This pin is the reference for the EN/DIM signal.
Bootstrap. A capacitor is connected between SW and BST pins to form a floating supply
across the power switch driver.
Switch Output. SW is the source of the internal MOSFET switch. Connect to the power
inductor and cathode of the Schottky rectifier.
Exposed pad should be connected to VSS.
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© 2012 MPS. All Rights Reserved.
4
MP4600 – WHITE LED DRIVER FOR UP TO 55 INCH TV BACKLIGHTING
OPERATION
The MP4600 is a current mode controlled BuckBoost regulator. The sensing resistor senses the
LED current and feeds it back to an error
amplifier, which regulates it to 198mV with an
inside compensation network. The COMP pin is
the output of the error amplifier. The inductor
peak current is proportional to the COMP pin
voltage. An increase of the COMP voltage
increases the current delivered to the output.
Open LED Protection
If the LED is open, there is no voltage on the FB
pin. The duty cycle will increase until VDD- VSS
reaches to 55V or VOVP-VSS reaches the
shutdown threshold set by the external resistor.
The top switch will turn off until the voltage VDDVSS and VOVP-VSS decreases sufficiently.
Dimming Control
The MP4600 allows both DC and PWM dimming.
When the voltage on EN is <0.6V, the chip is
turned off. For analog dimming, when the voltage
on EN is from 0.7V to 1.4V, the LED current will
change from 0% to 100% of the maximum LED
current. If the voltage on EN pin is higher than
1.4, maximum LED current will be generated. For
PWM dimming, its amplitude (VDIM – VINGND) must
exceed 1.5V. The PWM waveform is internally
clamped to 0.198V.
COMP
Figure 1—Functional Block Diagram
MP4600 Rev. 0.91
1/6/2012
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
5
MP4600 – WHITE LED DRIVER FOR UP TO 55 INCH TV BACKLIGHTING
APPLICATION INFORMATION
Setting the LED Current
An external resistor RSENSE is used to set the
maximum LED current through the use of the
equation:
0.198V
ILED
R SENSE =
FREQUENCY (kHz)
Series1
600
400
200
0
50
100
150
200
250
)
T
U
VO
+
N
⋅Δ
⋅
⋅
T
U
⋅Δ
fs
T
U
IL
)
,
>
T
U
O
T
U
⋅
V OV O
⋅
+
N
L
=
N
V IV I
(
fS
Selecting the Inductor
Inductor selection is related to the input voltage,
output voltage, and LED current. Select the
inductor to make the circuit always operate in
continuous current mode (CCM). The
inductance is designed as:
C
If RSET pin is floating, the setting frequency is
the default value 1.35MHz.
Selecting the Output Capacitor
The output capacitor keeps the output voltage
ripple ΔVOUT small (normally less than 1~5% of
the DC value) and ensures feedback loop
stable. The output capacitor impedance should
be low at the switching frequency. Ceramic
capacitors with X5R or X7R dielectrics are
recommended for their low ESR characteristics.
V OV I
(
D
T
E
U
IL O
V
0
+
T
U
800
⋅
)
1000
VI
(
1200
⋅Δ
N
I
1400
⋅
G
V
A
_
N
>
fs
CI
Frequency vs. RSET
O
TV
U
VO N
The input capacitor reduces the surge current
drawn from the input supply and the switching
noise from the device. Ceramic capacitors with
X5R
or
X7R
dielectrics
are
highly
recommended because of their low ESR and
small
temperature
coefficients.
Enough
capacitance is required for limited input voltage
ripple ΔVIN, which should be normally less than
5~10% of the DC value.
I LV
Setting the Switching Frequency
An external resistor RSET is used to set the
switching frequency fS according to the
following curve:
Selecting the Input Capacitor
PC Board Layout
The high current paths (VSS, VDD and SW)
should be aced very close to the device with
short, direct and wide traces. The input
capacitor needs to be as close as possible to
the VDD and VSS pins. The external feedback
resistors should be placed next to the FB pin.
Keep the switch node traces short and away
from the feedback network.
T
U
.
N
I
+
)
1
(
⋅
D
E
IL
G
V
A
_
IL
=
V OV
where ΔIL is the inductor peak-to-peak current
ripple. Design ΔIL as about 40% to 60% of the
inductor average current, which is:
IL
5
.
0
+
G
V
A
_
MP4600 Rev. 0.91
1/6/2012
=
IL
K
P
_
IL
Make sure the inductor is not saturated at the
maximum peak current, which is:
⋅Δ .
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© 2012 MPS. All Rights Reserved.
6
MP4600 – WHITE LED DRIVER FOR UP TO 55 INCH TV BACKLIGHTING
TYPICAL APPLICATION CIRCUITS
1
2
3
3
2
1
1
3
2
Figure 2—White LED Driver Application for TV Applications
MP4600 Rev. 0.91
1/6/2012
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
7
MP4600 – WHITE LED DRIVER FOR UP TO 55 INCH TV BACKLIGHTING
PACKAGE INFORMATION
3mm x 3mm QFN10
2.90
3.10
0.30
0.50
PIN 1 ID
MARKING
0.18
0.30
2.90
3.10
PIN 1 ID
INDEX AREA
1.45
1.75
PIN 1 ID
SEE DETAIL A
10
1
2.25
2.55
0.50
BSC
5
6
TOP VIEW
BOTTOM VIEW
PIN 1 ID OPTION A
R0.20 TYP.
PIN 1 ID OPTION B
R0.20 TYP.
0.80
1.00
0.20 REF
0.00
0.05
SIDE VIEW
DETAIL A
NOTE:
2.90
0.70
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.
3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX.
4) DRAWING CONFORMS TO JEDEC MO-229, VARIATION VEED-5.
5) DRAWING IS NOT TO SCALE.
1.70
0.25
2.50
0.50
RECOMMENDED LAND PATTERN
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications.
Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS
products into any application. MPS will not assume any legal responsibility for any said applications.
MP4600 Rev. 0.91
1/6/2012
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
8
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