MP3310
50V, 1.3A, Step-up
White LED Driver
with True PWM Dimming
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP3310 is a monolithic step-up converter
designed for driving arrays of WLEDs from a
wide input supply range. The MP3310 uses
current mode, fixed frequency architecture to
regulate the LED current to user programmed
value set by an external current setting resistor.
The switching frequency is also programmable
with an external resistor.
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The MP3310 features true PWM dimming,
which allows the flexible control of the
backlighting luminance under wide range of the
ambient brightness.
The MP3310 is turned off if an over-voltage
condition is present due to an open circuit
condition. Use one external resistor voltage
divider to program OVP threshold. The MP3310
also includes under-voltage lockout, current
limiting and thermal overload protection
preventing damage in the event of an output
overload.
Internal 0.3Ω Power MOSFET
Wide 4.5V to 25V Operating Input Range
Drives up to 12 Series White LEDs
Up to 93% Efficiency
True PWM Dimming
Adjustable Switching Frequency
Adjustable Open Load Shutdown Voltage
Internal 1.3A Current Limit
UVLO, Thermal Shutdown
Available in 3mm x 3mm QFN10 Package
APPLICATIONS
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LCD Panels
Digital Picture Frames
Handheld Computers and PDAs
Digital Still Cameras
Small LCD Displays
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“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
The MP3310 is available in small 10-pin QFN
3x3mm package.
TYPICAL APPLICATION
VIN vs. Efficiency
100
EFFICIENCY (%)
95
90
85
80
75
70
4
8
12
16
20
24
VIN(V)
MP3310 Rev.1.0
7/5/2011
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© 2011 MPS. All Rights Reserved.
1
MP3310—50V, 1.3A, STEP-UP WHITE LED DRIVER WITH TRUE PWM DIMMING
ORDERING INFORMATION
Part Number*
Package
Top Marking
Free Air Temperature (TA)
MP3310EQ
QFN10 (3mm x 3mm)
5R
-20°C to +85°C
* For Tape & Reel, add suffix –Z (e.g. MP3310EQ–Z);
For RoHS Compliant Packaging, add suffix –LF (e.g. MP3310EQ–LF–Z)
PACKAGE REFERENCE
(4)
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
VIN .................................................-0.3V to +30V
VSW, VLED .......................................-0.3V to +50V
All Other Pins ...............................-0.3V to +6.3V
(2)
Continuous Power Dissipation
(TA = +25°C)
............................................................. 2.5W
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature............... -65°C to +150°C
QFN10 (3mm x 3mm) ...........50 ...... 12 ... °C/W
Recommended Operating Conditions
(3)
Supply Voltage VIN ...........................4.5V to 25V
Operating Junc Temp TJ .......... -20°C to +125°C
MP3310 Rev.1.0
7/5/2011
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 is not guaranteed to function outside of its
operation conditions.
4) Measured on JESD51-7 4-layer board.
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© 2011 MPS. All Rights Reserved.
2
MP3310—50V, 1.3A, STEP-UP WHITE LED DRIVER WITH TRUE PWM DIMMING
ELECTRICAL CHARACTERISTICS
VIN = 12V, VEN = 5V, TA = +25°C, unless otherwise noted.
Parameters
Symbol
Operating Input Voltage
Supply Current (Shutdown)
Supply Current (Quiescent)
VIN
IIN_SD
IIN_QS
LDO Output Voltage
VCC
Switching Frequency
fSW
Maximum Duty Cycle
Under Voltage Lockout
IN Under Voltage Lockout
Under Voltage Lockout
Hysteresis
Open Load Shutdown
Threshold
Enable & Dimming
EN Low Threshold
EN High Threshold
EN Disable Timer
Current Regulation Delay
LED Current Regulation
LED Current
LED Regulation Voltage
Output Switch
SW On-Resistance
SW Current Limit
Thermal Shutdown
LED Switch (M2, refer block
diagram) On Resistance
MP3310 Rev.1.0
7/5/2011
Condition
Typ
Max
Units
1
25
1
2
V
µA
mA
4.3
5.0
5.5
V
470
0.8
90
560
1
650
1.2
kHz
MHz
%
3.6
3.9
4.2
V
4.5
VEN = 0V
VEN = 5V, VLED = 1V
VEN = 5V, 6V < VIN < 25V,
0 < IVCC < 10mA
RFSET = 50kΩ
RFSET Open
DMAX
VCC_UVLO
Min
VIN Rising
450
VOVP
VOV Rising
1.18
VEN_LOW
VEN_HIGH
VEN Falling
VEN Rising
0.6
1.24
mV
1.30
1.6
10
From VEN Rising Edge
ILED
VLED
RISET = 60kΩ
ILED = 80mA
RON
Duty Cycle = 90%
2
74.1
76.8
500
79.5
V
V
V
ms
µs
mA
mV
0.3
1.3
Ω
A
150
°C
2
Ω
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© 2011 MPS. All Rights Reserved.
3
MP3310—50V, 1.3A, STEP-UP WHITE LED DRIVER WITH TRUE PWM DIMMING
PIN FUNCTIONS
Pin #
Name
1
OVP
2
ISET
3
COMP
4
5
LED
Pin Function
Open Load Protection Programming Pin. Connect a resistor divider from output to this
pin to program the OVP threshold. When this pin voltage reaches the shutdown
threshold 1.24V, the switch will be turned off and latch up until the IC is turned off and
enabled again.
LED Current Set. Tie a current setting resistor from this pin to ground to program the
whole LED current.
Step-up Converter Compensation Pin. This pin is used to compensate the regulation
control loop. Connect a capacitor or a series RC network from COMP to GND.
LED Current Input. This pin is the open-drain output of an internal dimming
control switch. Connect the LED cathode to this pin. With internal 500mV
reference, the current flows into LED pin should be less than 120mA for normal
operation.
GND,
Ground. Connect exposed pad to GND plane for proper thermal performance.
Exposed Pad
6
SW
Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the
power inductor and output rectifier to SW.
7
EN/DIM
ON/OFF Control and Dimming Command Input. To use PWM dimming, add a 200Hz to
2kHz square wave signal to this pin.
8
VIN
Input Supply Pin. Must be locally bypassed.
9
VCC
The Internal 5V Linear Regulator Output. VCC provides power supply for the internal
MOSFET switch gate driver and the internal control circuitry. Bypass VCC to GND with a
ceramic capacitor. If VIN is less than 5.5V, apply an external 5V supply directly on VCC.
10
FSET
Switching Frequency Programming Pin. Connect a resistor to ground to set the switching
frequency.
MP3310 Rev.1.0
7/5/2011
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© 2011 MPS. All Rights Reserved.
4
MP3310—50V, 1.3A, STEP-UP WHITE LED DRIVER WITH TRUE PWM DIMMING
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 12V, VEN = 5V, ILED = 80mA, 10WLEDs 4Strings, unless otherwise noted.
PWM Dimming Duty vs.
WLED Current
VIN vs. Efficiency
100
90
80
90
85
80
75
70
60
fFSW(kHz)
WLED CURRENT (mA)
95
EFFICIENCY (%)
RFSET vs. fSW
50
40
30
20
200Hz
2kHz
10
70
4
8
12
16
VIN(V)
20
0
0 10 20 30 40 50 60 70 80 90100
PWM DIMMING DUTY (%)
24
Steady State
VSW
20V/div.
VOUT/AC
200mV/div.
VIEST
500mV/div.
VSW
20V/div.
VSW
20V/div.
VEN
5V/div.
VEN
5V/div.
VSW
20V/div.
VSW
20V/div.
PWM
2V/div.
PWM
2V/div.
ILED
50mA/div.
VOUT
10V/div.
ILED
50mA/div.
VOUT
10V/div.
2msdiv.
MP3310 Rev.1.0
7/5/2011
80
100
120
Open Load Protection
fPWM=2kHz, DPWM=50%
fPWM=200Hz, DPWM=50%
60
20usdiv.
PWM Dimming
PWM Dimming
40
ILED
50mA/div.
VOUT
10V/div.
4msdiv.
1usdiv.
20
Enable Shutdown
Enable Startup
VCMOP
500mV/div.
ILED
50mA/div.
IINDUCTOR
200mA/div.
1300
1200
1100
1000
900
800
700
600
500
400
300
200
0
VSW
20V/div.
VOUT
10V/div.
ILED
50mA/div.
200usdiv.
40usdiv.
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© 2011 MPS. All Rights Reserved.
5
MP3310—50V, 1.3A, STEP-UP WHITE LED DRIVER WITH TRUE PWM DIMMING
FUNCTION DIAGRAM
Figure 1—MP3310 Function Block Diagram
MP3310 Rev.1.0
7/5/2011
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© 2011 MPS. All Rights Reserved.
6
MP3310—50V, 1.3A, STEP-UP WHITE LED DRIVER WITH TRUE PWM DIMMING
OPERATION
The MP3310 employs a constant frequency,
peak current mode step-up converter and internal
regulated current source to regulate the array of
white LEDs. The operation of the MP3310 can be
understood by referring to the block diagram of
Figure 1.
Internal 5V Regulator
The MP3310 includes an internal linear regulator
(VCC). When VIN is greater than 5.5V, this
regulator offers a 5V power supply for the internal
MOSFET switch gate driver and the internal
control circuitry. The VCC voltage drops to 0V
when the chip shuts down. In the application of
VIN smaller than 5.5V, tie VCC and VIN together.
The MP3310 features Under Voltage Lockout.
The chip is disabled until VCC exceeds the
UVLO threshold. And the hysteresis of UVLO is
approximately 450mV.
System Startup
When the MP3310 is enabled and VCC exceeds
the UVLO threshold, the capacitor on COMP pin
is charged. Once the COMP level reaches to
about 750mV, the switching begins and the
MP3310 starts boosting the step-up converter.
Step-up Converter
The converter operation frequency is adjustable
by FSET setting resistor, which is helpful for
optimizing the external components sizes and
improving the efficiency.
At the beginning of each cycle, the power FET is
turned on with the internal clock. To prevent subharmonic oscillations at duty cycles greater than
50 percent, a stabilizing ramp is added to the
output of the current sense amplifier and the
result is fed into the PWM comparator. When this
result voltage reaches the output voltage of the
MP3310 Rev.1.0
7/5/2011
error amplifier (VCOMP) the power FET is turned
off.
The COMP voltage at the output of the internal
error amplifier is an amplified signal of the
difference between the 500mV reference voltage
and the feedback voltage. The converter
automatically provides enough bus voltage to
power the LED array.
If the feedback voltage drops below the 500mV
reference, the output of the error amplifier
increases. It results in more current flowing
through the power FET, thus increasing the
power delivered to the output. In this way it forms
a close loop to make the LED current in
regulation.
At light-load or VOUT near to VIN operation, the
converter runs into the pulse-skipping mode, the
FET is turned on for a minimum on-time, and
then the converter discharges the power to the
output in the remnant period. The FET will keep
off until the output voltage needs to be boosted
again.
Dimming Control
The MP3310 incorporates both Enable and PWM
dimming onto a single control pin. The part
features true PWM dimming which results in
PWM chopping of the current in the LEDs to
provide flexible LED brightness control.
Open Load Protection
The open load protection is achieved through the
over voltage protection. If LED array is open, the
LED pin is pulled to ground and the IC keeps
charging the output voltage until it reach OVP
threshold. Then the MP3310 shuts down the
step-up converter.
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© 2011 MPS. All Rights Reserved.
7
MP3310—50V, 1.3A, STEP-UP WHITE LED DRIVER WITH TRUE PWM DIMMING
APPLICATION INFORMATION
Setting the Switching Frequency
Selecting the Inductor
The resistor on FSET pin is used to set the
switching frequency. The relationship of the
operating frequency vs. the FSET resistor is
showed as the curve in page 5. A 20kΩ to 100kΩ
FSET resistor, which sets the operating
frequency from around 1.2MHz to 300kHz, is
recommended. Leaving the FSET pin open sets
the switching frequency to 1MHz as default.
A 10μH to 22µH inductor with a DC current rating
of at least 40% higher than the maximum input
current is recommended for most applications at
wide input range. For highest efficiency, the
inductor’s DC resistance should be as small as
possible.
Setting the LED Current
The regulated total LED current is identical and
set through the current setting resistor on the
ISET pin through the use of the equation:
ILED = 4605V / RISET
For RISET=60.4kΩ, the LED current is set to about
76.2mA. The ISET pin can not be open.
With internal 500mV reference, the current flows
into LED pin should be less than 120mA for
normal operation.
PWM Dimming
Apply a 200Hz to 2kHz square waveform to the
EN pin to implement PWM dimming of the LEDs.
The minimum recommended amplitude of the
PWM signal is 2V.
Setting the Over Voltage Protection
The open load protection is achieved through the
over voltage protection (OVP) setting. In some
cases, LED strings failure results in the feedback
voltage is always zero. The part then keeps
boosting the output voltage higher and higher. If
the output voltage reaches the programmable
OVP threshold, the protection will be triggered.
To make sure the chip functions properly in
normal operation, the OVP setting resistor divider
must be set with a proper value. The
recommended OVP point is about 1.3 times
higher than the output voltage for normal
operation.
VOV=1.24V x (R1+R2)/R2
MP3310 Rev.1.0
7/5/2011
Selecting the Input Capacitor
The input capacitor reduces the surge current
drawn from the input supply and the switching
noise from the device. The input capacitor
impedance at the switching frequency should be
less than the input source impedance to prevent
high frequency switching current from passing
through the input. Ceramic capacitors with X5R
or X7R dielectrics are highly recommended
because of their low ESR and small temperature
coefficients. For most applications, two 4.7μF
capacitors paralleled is sufficient.
Selecting the Output Capacitor
The output capacitor keeps the output voltage
ripple small and ensures feedback loop stability.
The output capacitor impedance should be low at
the switching frequency. Ceramic capacitors with
X7R dielectrics are recommended for their low
ESR characteristics. For most applications, a 1μF
ceramic capacitor is sufficient.
Layout Considerations
Careful attention must be paid to the PCB board
layout and components placement. Proper layout
of the high frequency switching path is critical to
prevent noise and electromagnetic interference
problems. The loop of MP3310 SW to GND pin,
output diode, and output capacitor is flowing with
high frequency pulse current. It must be as short
as possible. The IC exposed pad is internally
connected to GND pin. Lay the GND plane
widely for proper thermal performance. The VCC
pin is the power supply input for the internal
MOSFET switch gate driver and the internal
control circuitry. It must be locally bypassed.
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© 2011 MPS. All Rights Reserved.
8
MP3310—50V, 1.3A, STEP-UP WHITE LED DRIVER WITH TRUE PWM DIMMING
TYPICAL APPLICATION CIRCUIT
Figure 2—Step-up White LED Driver Application for Driving 4 Strings of 10 WLEDs
Figure 3—Step-up White LED Driver Application for Driving 3 Strings of 12 WLEDs
Figure 4—Step-up White LED Driver Application for Driving 3 Strings of 7 WLEDs
MP3310 Rev.1.0
7/5/2011
www.MonolithicPower.com
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© 2011 MPS. All Rights Reserved.
9
MP3310—50V, 1.3A, STEP-UP WHITE LED DRIVER WITH TRUE PWM DIMMING
PACKAGE INFORMATION
QFN10 (3mm x 3mm)
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. 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.
MP3310 Rev. 1.0
7/5/2011
www.MonolithicPower.com
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© 2011 MPS. All Rights Reserved.
10
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