MP3308 [MPS]
Step-up White LED Driver with Dual PWM Dimming Input Control;
| 型号： | MP3308 |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | Step-up White LED Driver with Dual PWM Dimming Input Control |
| 文件： | 总13页 (文件大小：314K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MP3308
Step-up White LED Driver
with Dual PWM Dimming Input Control
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP3308 is a monolithic step-up converter
designed to drive arrays of white LEDs from a
3.3V input or a single-cell lithium-ion battery.
The MP3308 uses fixed-frequency current-
mode architecture to regulate the LED current,
which is measured through an external current
sense resistor. Its low 200mV feedback voltage
reduces power loss and improves efficiency.
•
•
•
•
•
•
•
•
Internal Power MOSFET
Drives Up to 10 White LEDs in Series
2.2MHz Fixed Switching Frequency
Up to 88% Efficiency
Dual PWM-Dimming Input Control
Internal 1.3A Current Limit
±3% True PWM Dimming Duty Accuracy
Adjustable Over-Voltage Protection
Threshold
Low 200mV Feedback Voltage
Under-Voltage Lockout, Short-Circuit
Protection, Thermal Shutdown
Available in 3mmx4mm QFN14 Package
The MP3308 features dual PWM-dimming input
control and true PWM dimming—this control
allows for a wide luminescent range that makes
the display readable under a variety of ambient
light conditions with minimal PWM dimming
noise.
•
•
•
APPLICATIONS
The MP3308 includes over-voltage protection,
short-circuit protection, under-voltage lockout,
current limiting, and thermal overload protection.
•
•
•
•
•
Small LCD Panels
Digital Picture Frames
Smartphones
Portable Media Players
Digital Cameras
The MP3308 is available in small 3mmx4mm
14-pin QFN package.
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Products, Quality Assurance page.
“MPS” and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
L
D
VOUT
VIN
CIN
C
OUT
IN
SW
EN
Enable
PWMIA
PWMIB
PWMOA
PWMOB
FSET
LED
ISET
MP3308
R
R
ISET
R
OVP1
OVP
C
OA
COB
GND
OVP2
C
FSET
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
1
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
ORDERING INFORMATION
Part Number*
Package
Top Marking
MP3308DL
QFN14 (3x4mm)
3308
For Tape & Reel, add suffix –Z (e.g. MP3308DL-Z).
For RoHS, compliant packaging, add suffix –LF (e.g. MP3308DL–LF–Z).
PACKAGE REFERENCE
TOP VIEW
PIN 1 ID
1
2
3
4
5
6
7
14
13
12
11
10
9
8
EXPOSED PAD
ON BACKSIDE
CONNECT TO GND
QFN14 (3x4mm)
Thermal Resistance (4)
QFN14 (3x4mm) .....................48 ...... 10...°C/W
θJA
θJC
ABSOLUTE MAXIMUM RATINGS (1)
SW Pin, LED Pin...........................-0.5V to +40V
All Other Pins...............................-0.3V to +6.5V
Storage Temperature............... -55°C to +150°C
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-to-
ambient 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.
(2)
Continuous Power Dissipation (TA = 25°C)
………………………………………………....2.6W
Recommended Operating Conditions (3)
Supply Voltage (VIN)..............................3V to 6V
SW Pin................................................VIN to 36V
Operating Junction Temp. (TJ). -40°C to +125°C
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
2
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
ELECTRICAL CHARACTERISTICS
VIN = VEN = 5V, TA = 25°C, unless otherwise noted.
Parameters
Symbol Condition
Min
Typ Max Units
Operating Input Voltage
Supply Current (Shutdown)
Supply Current (Quiescent)
Switching Frequency
Maximum Duty Cycle
Under Voltage Lockout
VIN Under Voltage Lockout
Under Voltage Lockout Hysteresis
Over-Voltage Protection Threshold
Enable and Dimming
EN/PWMIX OFF Threshold
EN/PWMIX ON Threshold
True PWM Dimming Duty Accuracy
Feedback
VIN
2.5
6
V
µA
µA
MHz
%
IIN_SD
IIN_QS
fSW
VEN = 0V
25
860
2.2
30
VISET = 0.3V
1.7
90
2.7
2.3
DMAX
VISET = 0V
VIN Rising
VOUT Rising
VUVLO
VOVP
2.1
30
V
mV
V
0.9
VLOGIC_LOW VEN Falling
0.4
V
V
VLOGIC_HIGH VEN Rising
1.8
∆DDPWM D_PWMIA=D_PWMIB=70%
±3
%
ISET Voltage
VISET
VEN > 2V
185
200
215
mV
nA
ISET Input Bias Current
Output Switch
VISET = 0.2V
-600 -300
SW On-Resistance
RON
0.4
1.33
150
Ω
A
SW Current Limit
Duty Cycle = 60%
Thermal Shutdown
°C
LED Switch ON-Resistance (M2 in
the functional block diagram)
0.8
Ω
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
3
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
PIN FUNCTIONS
Pin #
Name
Description
Power Switch Output. Drain of the internal MOSFET switch. Connect to the power
inductor and the output rectifier. SW can swing between GND and 40V.
1
SW
PGND,
Exposed Pad
2
3
4
Power Ground. Connect exposed pad to GND plane for proper thermal performance.
IN
Input Supply Pin. Locally bypassed.
PWM Input A. Apply one PWM signal on this pin for brightness control. This signal is
uniform and filtered at PWMOA pin.
PWMIA
PWM Input B. Apply the other PWM signal on this pin for brightness control. This signal
is uniform and filtered at PWMOB pin.
5
6
7
PWMIB
EN
ON/OFF Control. Hold EN pin low to turn off part, high to turn of part.
PWM Dimming Frequency Programmer. Connect a capacitor from this pin to GND to set
the PWM-dimming frequency as the formula, FPWM(Hz) = 16176 / CFSET(nF)
FSET
8
9
PWMOB
PWMOA
GND
PWM Filtered Output B. Connect a capacitor from this pin to GND.
PWM Filtered Output A. Connect a capacitor from this pin to GND.
Ground.
10,14
Over-Voltage Protection. Connect a resistor divider from output to this pin to adjust the
OVP threshold. When this pin voltage reaches the shutdown threshold 0.9V, the switch
turns off.
11
12
13
OVP
LED
ISET
LED Current Input. Open-drain output of an internal dimming control switch. Connect the
LED cathode to this pin.
LED Current Set. This pin is the source output of an internal dimming control switch. The
MP3308 regulates the voltage across the current setting resistor. Tie a current-setting
resistor from this pin to ground. Regulates the voltage to 200mV.
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
4
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
TYPICAL CHARACTERISTICS
V(Iset) vs. Temperature
V(OVP) vs. Temperature
204.000
203.000
202.000
201.000
200.000
199.000
198.000
0.893
0.890
0.887
0.884
0.881
0.878
0.875
-50
0
50
100
150
-50
0
50
100
150
Quiescent Current vs.
Temperature
Operation Frequency vs.
Temperature
2.5
2.45
2.4
900
890
880
870
860
850
840
830
820
810
800
2.35
2.3
2.25
2.2
2.15
2.1
2.05
2
-50
0
100
150
50
-50
0
50
100
150
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
5
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
TYPICAL PERFORMANCE CHARACTERISTICS
VIN =5V, 3 LEDs in series, 9 strings parallel, 120mA/string, unless otherwise noted.
Efficiency vs. V
PWMIA Dimming Duty vs.
WLED Current
PWMIB Dimming Duty vs.
WLED Current
IN
180
160
140
120
100
80
180
160
140
120
100
80
60
60
40
40
20
20
3
3.5
4
4.5
5
5.5
6
6.5
VIN (V)
PWMIA DUTY CYCLE
PWMIB DUTY CYCLE
PWMIA*DPWMIB vs.
WLED Current
Steady State Operation
V
Power On
IN
180
160
140
120
100
80
V
SW
V
SW
5V/div.
5V/div.
V
OUT
5V/div.
V
OUT
60
5V/div.
V
IN
V
IN
5V/div.
40
5V/div.
I
20
L
WLED Current
100mA/div.
500mA/div.
PWMIA/B DUTY CYCLE
V
Shut Down
EN Power On
EN Shut Down
IN
V
V
V
SW
SW
SW
5V/div.
5V/div.
5V/div.
V
OUT
V
OUT
V
OUT
5V/div.
V
5V/div.
5V/div.
5V/div.
EN
V
IN
V
EN
5V/div.
5V/div.
WLED Current
100mA/div.
WLED Current
100mA/div.
WLED Current
100mA/div.
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
6
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Open Load Protection
Short Protection
V
SW
10V/div.
V
SW
5V/div.
V
SW
V
OUT
5V/div.
PWMib
5V/div.
5V/div.
V
OUT
V
PWMia
5V/div.
LED
5V/div.
5V/div.
I
OUT
WLED Current
200mA/div.
1A/div.
WLED Current
100mA/div.
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
7
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
FUNCTIONAL BLOCK DIAGRAM
POWER
FOR
BLOCKS
LED
Regulator
ERROR
IN
PWM
AMPLIFIER
COMPARATOR
ISET
SW
M2
Control
logic
M1
ISET
EN
ENABLE
FOR
BLOCKS
ENABLE&
DIMMING
GENERATOR
GND
OVP
CURRENT
SENSE
AMPLIFIER
PWMIA
PWMIB
Dual PWM
Dimming Control
OSC
0.9V
OVP
COMPARATOR
PWMOA
PWMOB
FSET
Figure 1—Functional Block Diagram
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
8
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
OPERATION
The MP3308 uses a constant-frequency peak-
current–mode boost-regulator architecture to
regulate multiple strings of white LEDs connected
in series.
External capacitors on the PWMOA and the
PWMOB pins smooth the PWM signals to
provide DC signals by selecting the proper time
constant.
At the start of each oscillator cycle, the control
circuitry turns on the MOSFET. A stabilizing ramp
at the output of the current sense amplifier
prevents sub-harmonic oscillations at duty cycles
greater than 50 percent—this output feeds into
the positive input of the PWM comparator. When
this voltage equals the output voltage of the error
amplifier the power MOSFET turns off.
MP3308 provides over-voltage protection, which
will shut off the MP3308 if the output voltage
goes too high. OVP pin senses the output
voltage through the tap of a resistor divider
between VOUT and GND. In the case of an LED
failure, the feedback voltage goes to zero and the
part will run at maximum duty cycle. The output
voltage then rises and triggers OVP if the OVP
pin exceeds 1.23V.
The error amplifier compares the difference
between the 200mV reference voltage and the
feedback voltage. If the feedback voltage drops,
the output of the error amplifier increases,
resulting in more current flowing through the
power MOSFET and increasing the power
delivered to the output, thus regulating the output.
MP3308 also provides short-circuit protection in
cases where individual LEDs on a string or a
whole LED string shorts: This condition causes
the ISET pin to pull high. If the voltage exceeds
0.4V for more than 240µs, MP3308 will shutdown.
Dual PWM dimming can adjust LED brightness.
True PWM dimming allows for flexible control of
the backlighting luminance to improve visibility for
a wide range of ambient brightness. A capacitor
on the FSET pin sets the PWM dimming
frequency with a duty cycle of:
DPWMIA ×DPWMIB
Where DPWMIA is the duty cycle on the PWMIA pin,
and DPWMIB is the duty cycle on the PWMIB pin.
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
9
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
APPLICATION INFORMATION
L1
C1 C2
D1
VIN
B0530
C3
JP1
U1 MP3308
C5
NS NC
1
2
3
4
5
6
7
14
13
12
11
10
9
R5
SW
GND
ISET
R1
1
R2
Bias
LED+
LED-
R3
160k
100
C4
0.1
C10
33nF
PGND
IN
LED
R6
PWMIA
PWMIB
EN
OVP
PWMA
PWMB
EN
C6
NS
10k
R7
R4
10k
GND
10k
R8
PWMOA
PWMOB
10k
8
R9
100k
R10
100k
R11
100k
FSET
C8
C9
C7
10nF
68nF 68nF
Figure 2—Typical Application Driving 9 Strings of 3 WLEDs
Figure 2 shows a typical application circuit that
can drive up to nine strings of three white LEDs
with an output of 9V/180mA. A 4.7µF output
capacitor is sufficient for most applications. A
3.3µH inductor with low DC inductor resistance
(DCR) will improve efficiency. Two 4.7μF ceramic
capacitors provide sufficient input decoupling.
Use Schottky diodes with fast recovery for high
frequencies, and rated for a 500mA peak
inductor current. An internal soft-start limits IIN at
startup and IOUT overshoot.
Table 1—ILED vs. R1
ILED (mA)
R1 (Ω)
200
40
1
5
10
20
60
180
200
20
10
3.33
1.11
1
PWM Dimming
The ramped voltage added to the current sense
amplifier reduces the maximum output current as
the duty cycle increases. As more LEDs are
added, the output voltage rises but the maximum
current delivered to the load falls as well.
PWM dimming requires the application of square
waves to both the PWMIA and the PWMIB pins.
A capacitor on the FSET pin sets the PWM
dimming frequency according to the equation:
FPWM(Hz) = 16176 / CFSET(nF),
For CFSET=10nF, the FPWM is set to 1.6kHz.
The recommended FPWM range is 50Hz to 50kHz.
Setting the LED Current
The resistor R1 sets the LED current, where the
current value is given by:
The minimum recommended amplitude of the
PWM signal is 2V.
200mV
I
LED
=
R1
External capacitors on both PWMOA and
PWMOB, together with internal 100kΩ resistors
filter the square waveform to provide a DC value.
The time constant should be ten times greater
than a PWM waveform cycle:
Table 1 pairs resistor values with an LED current.
RC > 10⋅TPWM
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
10
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
Selecting the Inductor
Layout Considerations
Layout requires special consideration to avoid
electromagnetic interference from the high-
frequency switching path. The high-frequency
ripper current in the loop from the SW pin,
through the output diode, and output capacitor to
GND requires a connection loop that is as short
as possible.
The inductor forces a higher output voltage
driven from a lower input voltage. A larger
inductor value results in less ripple current, a
lower peak inductor current, and reduces stress
on the internal N-Channel MOSFET. However,
larger-value inductor has a larger physical
footprint, higher series resistance, and lower
saturation current.
The IN pin must be locally bypassed, with a
highly-recommended RC filter to eliminate noise.
See Figure 3 for an example of this circuit.
Choose an inductor that does not saturate under
the worst-case load conditions. Calculate the
required inductance value using the following
equations:
L1
C1 C2
D1
VIN
B0530
η× VOUT × D×(1− D)2
L ≥
JP1
U1 MP3308
2× fSW × ILOAD
1
2
3
14
13
12
R5
SW
GND
ISET
LED
Bias
100
V
IN
C4
0.1
PGND
IN
D = 1−
VOUT
Where VIN and VOUT are the input and output
voltages, fSW is the switching frequency, ILOAD is
the LED load current, and η is the efficiency.
Figure 3—Input Bias Filtering
Over-Voltage Protection
Open Load protection will shut off the MP3308 if
the output voltage reaches over-voltage
protection (OVP) threshold. LED failures will
result in the feedback voltage falling to zero,
which will cause the part to run at maximum duty
cycle and boost the output voltage. If the output
voltage exceeds the adjusted OVP threshold:
R2
VOV =0.9V(1+
) ,
R3
The MP3308 will shut down and will not remain
off until the power cycles.
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
11
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
TYPICAL APPLICATION CIRCUITS
C1 C2
L1
D1
VIN
B0530
C3
JP1
U1 MP3308
C5
NS NC
1
2
3
4
5
6
7
14
13
12
11
10
9
R5
SW
GND
ISET
R1
1
R2
LED+
LED-
Bias
R3
100
C4
160k
PGND
IN
C10
33nF
LED
R6
PWMIA
PWMIB
EN
OVP
PWMA
PWMB
EN
C6
NS
10k
R7
R4
10k
GND
10k
R8
PWMOA
PWMOB
10k
8
R9
R10
R11
100k
FSET
VIN Bias Circuit
C8
C9
C7
10nF
100k 100k
68nF 68nF
LED+
R12
900
Bias
D2
Figure 4— Driving 27 WLEDs (9 WLEDs in Series and 3 Strings Paralleled) with 3V-3.3V Input Voltage1
(1) Use additional bias circuit for low input voltage compatibility.
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
12
MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
PACKAGE INFORMATION
QFN14 (3x4mm)
1.60
1.80
2.90
3.10
0.30
0.50
PIN 1 ID
SEE DETAIL A
PIN 1 ID
MARKING
1
14
0.18
0.30
3.20
3.40
3.90
4.10
PIN 1 ID
INDEX AREA
0.50
BSC
8
7
TOP VIEW
BOTTOM VIEW
PIN 1 ID OPTION A
0.30x45º TYP.
PIN 1 ID OPTION B
R0.20 TYP.
0.80
1.00
0.20 REF
0.00
0.05
SIDE VIEW
DETAIL A
2.90
1.70
NOTE:
0.70
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.
3) LEAD COPLANARITY SHALL BE0.10 MILLIMETER MAX.
4) JEDEC REFERENCE IS MO-229, VARIATION VGED-4.
5) DRAWING IS NOT TO SCALE.
0.25
0.50
3.30
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.
MP3308 Rev. 1.02
7/19/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
13
相关型号：
©2020 ICPDF网 联系我们和版权申明